got a cross fire corvette

Discussion in 'Engine: Repairs and Modifications & generally corv' started by grumpyvette, Nov 2, 2008.

  1. grumpyvette

    grumpyvette Administrator Staff Member

    Got these pics from another forum; they are of the new Renegade manifold for the CFI installed on a 1984.
    The following is a statement from the makers DCS:

    Please note that we are not releasing any internal pics or technical specs at this time. The reason for this is the design is not 100% finalized - we are still tweaking things. But here is some basic info.

    * Runner cross sectional area is presently approx 30% larger.
    * There is a 20% taper from inlet to outlet.
    * True Crossram design style with optimized runner configuration but modified for our application.
    * The outlet is slightly smaller than a 1205 gasket. This is done to make sure there are no leaks and a good seal is obtained.
    * Plenum area is 20% larger than stock.
    * True OE design on the top plate. All brackets are in their stock locations. Just bolt it on and everything is located where it should be.
    * Same overall height as the stock manifold.
    * EGR is built in if it is needed.
    * No issues with removing valve covers.

    http://www.technovelocity.com/chevyhack ... olish.html
    462624
    350
    76-87
    1.94/1.50 2.02/1.60
    [​IMG]
    heads tend to crack if over heated or incorrectly torqued
    if you have zero deck to head distance I'd suggest a .040-.042 thick head gasket should be used

    for a 9.3 compression, 327 with a 3.08 rear gear, and auto trans, Id suggest a cam like a crane 114132

    https://www.summitracing.com/parts/crn-114132

    with the correct matched components 350 hp should be doable, btw mild port and bowl area clean-up can allow these heads to have improved flow, they will never be a great choice but they can be improved
    use of long tube headers a low restriction exhaust and a cam with a bit more lift and duration can help compensate for the restrictive ports some what.
    I would certainly suggest a decent performance dual plane intake be selected,and port matched, and you certainly don,t need to spend a fortune
    something like this easily improves flow if matched up correctly

    https://www.summitracing.com/parts/wnd-8150

    http://www.usaperform.com/sbc-torqu...-lifter-kit-275-deg-278-deg-435-455-lift.html

    http://garage.grumpysperformance.com/index.php?threads/refresh-1982-crossfire-vette.14173/

    http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/

    http://garage.grumpysperformance.co...-by-step-guide-with-pictures.5378/#post-60990

    http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/

    http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/
    We decided to use my 84 as the mule because of the hood clearance concerns. 82 Vettes are roomier in the engine compartment.


    YOU MAY WANT TO READ THRU THESE LINKs

    http://www.thecubestudio.com/CrossfireT ... ration.htm

    http://www.thecubestudio.com/CrossfireT ... ancing.htm

    http://www.thecubestudio.com/CrossfireT ... ration.htm

    http://crossfireinjection.net/DCS News.html

    http://www.technovelocity.com/chevyhack ... olish.html

    [​IMG]
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    this may interest you
    http://www.ecklerscorvette.com/corv...nifold-crossfire-injection-1982-and-1984.html

    THE HEADS ON THE 1984 cross fire corvettes are pathetic also

    Heads: Iron, casting number 462624
    Chamber Volume: 76cc
    Intake Valve size: 1.94"
    Exhaust Valve size: 1.50"
    Intake Port Volume: 158cc
    Flow Numbers:
    .100
    44/41
    93.2%
    .200
    101/82
    81.2%
    .300
    155/125
    80.6%
    .400
    182/137
    75.3%
    .500
    196/140
    71.4%
    Average
    159/121
    76.3%


    NOW COMPARE THOSe NUMBERS

    viewtopic.php?f=32&t=5521&p=16619&hilit=head+flow+numbers#p16619

    viewtopic.php?f=52&t=333&p=27234&hilit=head+flow+numbers#p27234

    viewtopic.php?f=52&t=462&p=24466&hilit=head+flow+numbers#p24466

    viewtopic.php?f=52&t=5078&p=18935&hilit=head+flow+numbers#p18935

    viewtopic.php?f=52&t=401&p=17237&hilit=head+flow+numbers#p17237

    viewtopic.php?f=52&t=5364&p=16066&hilit=head+flow+numbers#p16066

    http://www.airflowresearch.com/articles ... 5/A-P1.htm

    viewtopic.php?f=52&t=2630&p=13142&hilit=head+flow+numbers#p13142

    viewtopic.php?f=52&t=1563&p=11967&hilit=head+flow+numbers#p11967

    viewtopic.php?f=52&t=4221&p=11119&hilit=head+flow+numbers#p11119

    viewtopic.php?f=52&t=8460&p=32923#p32923

    viewtopic.php?f=52&t=322&p=9895&hilit=head+flow+numbers#p9895

    if you have a cross fire 1984 corvette with dual throttle body injection your dealing with what is eventually a very restrictive set of heads fed by an extremely restrictive intake on an engine thats designed to operate at under 4000rpm, that makes a factory rated power curve under 220 hp.

    your original cross fire throttle body injection intake was and is VERY RESTRICTIVE, there are far better intake manifolds, cylinder heads and cams available, to upgrade a cross fire corvette. , for both upgrading the TBI or swapping to a carburetor fueled engine


    READ A FEW LINKS, and sub links, it should take you a few hours to read most of the related info but it could save you weeks of work and a good deal of ca$h


    viewtopic.php?f=32&t=1148&p=2333&hilit=1984+crossfire#p2333

    viewtopic.php?f=32&t=1401

    viewtopic.php?f=32&t=596

    viewtopic.php?f=32&t=2697

    viewtopic.php?f=32&t=10096&p=39656&hilit=shop+manual#p39656

    IF YOU WANT A CROSS FIRE CORVETTES ENGINE TO BREATH YOULL NEED TO MAKE CHANGES
    http://www.crossfireinjection.net/renegade.htm
    renegade intake
    http://www.cranecams.com/product/cart.php?m=product_detail&p=23790
    mild cam
    better heads
    http://www.airflowresearch.com/index.php?cPath=24_117
    roller rockers
    http://www.ebay.com/itm/Scorpion-Ro...-16-/391143932929?hash=item5b11fec401&vxp=mtr
     
    Last edited by a moderator: Sep 29, 2017
  2. grumpyvette

    grumpyvette Administrator Staff Member

    Ive had several cross fire owners driving the 1984 corvettes ask about upgrading to the TPI as it flows a bit better and makes even better power than the crossfire engine, and the real question , that instantly brings up is why would any sane person going thru the trouble time and expense to upgrade from a totally restrictive cross fire system to a new EFI system select a stock TPI when theres several much better options
    really you have two valid options, you can either upgrade the current intake, with a custom, or renegade intake, which is basically a parts swap, that will increase the engines ability to breath with a much less restrictive intake design, but one that allows you to keep the stock throttle body's and computer controls, sensors, etc.
    keep in mind before you make any changes step back mentally and ask yourself what your real goal and budgets are and if you can reasonably expect to reach that goal with your budget and skill level, a bit of research can save you a great deal of wasted time and cash. If you take the time to do a bit of research youll find that you have several options, and starting with the basic 1984 sbc engine MIGHT NOT be the best choice if you want more than about 350-375 hp
    CROSSFIRE

    [​IMG]

    http://www.technovelocity.com/chevyhack ... olish.html
    http://auto.howstuffworks.com/1984-corvette3.htm
    keep in mind , if your starting with a stock cross fire 350 corvette engine, your only starting with a stock 205 hp/290 ft lbs of torque... one of the first questions most guys who own a cross fire engine ask is whats the best cam upgrade, well obviously the answer is dependent on several factors like what if any other mods are to be done to the engine, but if your corvettes essentially to remain basically stock other than the cam swap upgrade Ive had very good results with the CRANE 114122 for cars with an automatic transmission (usually worth about 22-25 rear wheel hp with zero bad habits) or the CRANE 114132 with cars having a manual trans.(usually worth about 30-35 rear wheel hp with zero bad habits) and in either case 1.6:1 roller rockers seem to add additional responsiveness, but obviously clearances in the valve train must be verified and if necessary corrected
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    http://ww2.justanswer.com/uploads/JHoop ... 3230_1.pdf
    84v1.pdf
    84v2.pdf
    84v3.pdf

    viewtopic.php?f=32&t=640&p=25767&hilit=crossfire#p25767

    or get something noticeably better , but to take advantage of that youll also want better cylinder heads cam upgrade and headers, with a low restriction exhaust.

    [​IMG]
    [​IMG]
    if you want to perk up a cross fire corvette porting the stock cross fire intake and a cam swap helps
    but replacing a stock restrictive intake to a converted SY1 or SMOKEY RAM INTAKE, or the new renegade is a HUGE improvement in air flow!
    [​IMG]
    Still think you should look into the SY1 Edelbrock intake(pictured above), there is only so far you can go with the CFI intake

    viewtopic.php?f=32&t=10096&p=39656#p39656

    IF your thinking you can port the stock intake and heads......Ive got some advice gained thru experience

    don,t get the idea I'm against the x-fire system,design, it has potential,
    I'm just against throwing money down a rat hole!
    one option....selecting the aftermarket cross-ram bases matched to a correctly matched cam, better heads and a low restriction exhaust with decent headers can make a huge improvement.
    but the stock intake, heads and cam are KILLING your potential power



    SHORT ANSWER! STOP BEATING A LONG DEAD HORSE!!

    Ive been playing at the hp wars for years,your stock heads,intake, displacement and compression ratio and cam are killing performance. the cross fire intake is the worst offender as it only flow about 170cfm-190cfm
    swapping to a EDELBROCK SY1 OR OFFY CROSS-RAM INTAKE with CUSTOM LID removes that restriction
    THE EXTREMELY RESTRICTIVE STOCK INTAKE

    [​IMG]
    custom lid SY1
    [​IMG]

    compare the ports, the SY1 flows about 270cfm
    [​IMG]

    IF its to retain the stock auto transmission and rear gear ratio,
    <b>"A MODIFIED EDELBROCK SY1 WITH CUSTOM TOP MATCHED TO 190CC AFR HEADS, or BRODIX IK HEADS, or TRICKFLOW 195 cc HEADS, CRANE 114142 CAM -- AND add a 383 high compression engine kit"
    but if youve got a MANUAL TRANSMISSION, and a 3.54:1-3.73:1 rear gear, you can step up too a significantly more aggressive cam like a crower 00320, if your willing to put up with a lopey idle and adjusting flat tappet lifters occasionally, but you WILL NEED TO HAVE EITHER SWAPPED TO A CARBURETOR(S) OR DRASTICALLY RE-PROGRAMED THE COMPUTER CONTROLS ON THE EFI if you've retained the TB injection, and naturally swapping to carburators requires a different fuel supply and pressure regulator,
    http://www.crower.com/misc/cam_spec/cam ... &x=35&y=12

    b>
    BTW Ill save you the math, you'll need to get the 10:1 cpr flat top piston 383 kit for the street, and the 74cc combustion chambers AFR 190cc HEADS with L98 spark plug angles if you intend to run high test gas you find everywhere (some is lousy quality) and get the head gasket as close to .018-.022 as you can for correct quench
    fyi DD-2000 and EA pro both guess at OVER a 115 hp improvement at the rear wheels, having done this type mod in the past Im reasonably sure that's UNDERESTIMATED for those listed changes

    383 rebuild kit $1000
    http://www.strokerkits.com/383.htm]http://www.strokerkits.com/383.htm
    crane cam/lifters $150
    AFR heads $1200 http://www.flatlanderracing.com/cyl...//www.flatlanderracing.com/cylhead_index.html
    SY1 with custom lid $500-$600
    DOING YOUR OWN WORK>>>>>PRICELESS! :thumbs: :thumbs:
    [​IMG]
    offy
    [​IMG]


    Part numbers are 5893 base,
    http://store.summitracing.com/partdetail.asp?autofilter=1&part=OFY-5893&N=700+400429+115&autoview=sku

    5903 for the dual-four top,
    http://store.summitracing.com/partdetail.asp?part=OFY-5903

    5902 for the linkage.

    http://store.summitracing.com/partdetail.asp?part=OFY-5902



    both SUMMIT AND JEGS CAN GET IT FOR YOU

    MORE USEFUL INFO

    http://www.swko.net/~lionsden/crossfire.htm

    http://www.swko.net/~lionsden/crossfire1.htm

    http://www.thecubestudio.com/CrossfireT ... ration.htm

    http://www.thecubestudio.com/CrossfireT ... ancing.htm

    unless your rich or hopelessly masochistic get a SY1 or OFFY BASE
    [​IMG]

    the sy1 flows close to 270cfm out of the box, a cfi flows 170-190cfm (DEPENDS ON WHICH PORT (STOCK) and theres not enough room to port without cutting/welding (EXPENSIVE AND TIME CONSUMING AND EASILY SCREWED UP)

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    If you intend to build a SBC with a corvette cross fire engine as a starting point,
    we certainly have a good deal of related info you can use.


    THERES MORE BUT ID START WITH THESE THREADS
    carefully reading the threads and links will be very helpful.
    as youll see the web site is set up to teach and answer questions and if you have anything , youve learned that might help other members ,please post the tips, pictures and info.

    http://garage.grumpysperformance.co...egade-intake-for-cross-fires.2796/#post-54235

    http://garage.grumpysperformance.com/index.php?threads/got-a-cross-fire-corvette.640/#post-5467

    http://garage.grumpysperformance.co...-fire-intake-porting-or-upgrade.102/#post-126

    http://garage.grumpysperformance.com/index.php?threads/head-and-cam-swap-82-cfi.10412/#post-43216

    http://garage.grumpysperformance.com/index.php?threads/crossfire-sleeper.12732/page-2#post-69838

    theres a great deal that can be done, but I'm forced to point out that the Stock cylinder heads and intake are killing the engines potential, and obviously both your budget and skills might limit or increase your options, upgrading the intake and heads and cam will be key to good results, obviously a low restriction exhaust and headers and possibly a increase in compression and displacement sure helps
    THEY WILL NOT SUPPORT A LARGE INCREASE IN HP WITHOUT MASSIVE CUTTING AND RE WELDING WORK,WHICH COSTS FAR MORE AND WORK FAR LESS EFFECTIVELY THAN AN SY1 SWAP WITH A CUSTOM LID


    [​IMG]
    this is the port work necessary to get them to flow even as pitifully as a TPI
    for those guys that suggest swapping to a LT1-4 and MPFI on your 1984 crossfire...
    just so your not confused, or under the wrong impression, the offanhauser intake base significantly out flows even a ported LT4 intake,doesn,t require re-plumbing the coolant flow like on the LT4 intake,(remember the LT1 and LT4 have no place to install a radiator hose or distributor in stock form),the offy, will function with minimal rewiring,and has a wider effective power band ONCE ITS CORRECTLY MODIFIED with the correct dual TB top or if you just use the dual 4 barrel top plate and a couple 650cfm carbs like many guys use, plus if its correctly done the engine appears to remain stock too the average casual inspection as you can still use the stock air cleaner assembly with the custom TB top, but the windshield wiper motor needs to be replaced with a smaller version for clearance issues

    one of the most restrictive components on the x-fire is the less than ideal #624 casting cylinder heads, one factor that gets discussed a great deal is the difference in port size or port CCs, the sad truth is that Id bet 90% of the discussions are just guys repeating stuff they have heard with zero real idea what they are talking about.
    while theres generally some relation of port cross sectional area to the listed port CCs its NOT a direct linear relationship, and its the cross sectional area,shape, length and surface finish not the port CCs that matter to the air flow., and if the exhaust system can,t effectively scavenge the cylinders or the intake can,t supply the flow, or the cam duration and lift don,t match the intended port flow rates performance will suffer

    The first thing I hear is usually some guy suggesting vortec heads, as an example its been my experience that standard vortecs become a restriction above about 4500rpm compared to several options, and are not the best selection if your trying to exceed 430hp, (vortecs also require an intake and rockers and valve covers that match) the BRODIX,AFR and TRICKFLOW heads in the 180cc-200cc range matched to a decent cam and a better intake can produce a huge boost over a stock x-fire

    you don,t build an engine combo by selecting just heads, first and then matching the other components to that head flow rates, you select a hp/torque/rpm power band as a goal and then select the necessary components to slightly exceed that hp/torque/rpm power bands requirements knowing all parts NEVER work at 100% of the potential when matched in a combo.
    http://forum.grumpysperformance.com/viewtopic.php?f=52&t=322

    [​IMG]

    http://www.dynamicefi.com/TBI_Fueling.php
     
    Last edited by a moderator: Aug 25, 2017
  3. grumpyvette

    grumpyvette Administrator Staff Member

    http://www.crossfireinjection.net/catalog.htm
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    JUST CURIOUS?
    not knocking or praising this product
    just looking forward to testing one
    and yes Im only too familiar with the delays and problems of producing components on more than a custom,one of basis,
    for at least a year Ive heard rumors that the RENEGADE x-fire intakes will be available shortly and they have a PRE-BUY deal going, but It seems like its always taking a little longer ...........I was wondering if any ones seen any progress or knows whats REALLY going on here , when products are ACTUALLY going to be delivered
    these might be a really nice intake, but until I have one to test & tune its just pie in the sky
    so I was hoping you guys have the strait scoop

    Dynamic Crossfire Solutions
    http://www.crossfireinjection.net/
    http://www.crossfireinjection.net/
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    WELL THE DYNO RESULTS ARE IN
    The new RENEGADE intake ALONE on a stock crossfire engine, with its factory intake, replaced, with the newer renegade intake, produces 32 hp and 16 lbs/ft of torque at the rear wheels over the stock crossfire intake, adding better flowing heads like the AFR or BRODIX , profiler or TRICKFLOW heads,

    below a mildly ported OEM cross fire intake with its restricted runner design
    [​IMG]
    http://www.airflowresearch.com/index.php?cPath=24_29
    http://www.summitracing.com/parts/bro-1021001/overview/
    http://www.trickflow.com/partdetail.asp ... toview=sku
    http://www.profilerperformance.com/raci ... -23-degree
    in the 195cc-210cc range and a decent cam like a CRANE 114132 (btw thats a good street cam for the basic crossfire engine but with a 3.73:1 rear gear, and a higher stall converter speed it can use a bit more cam than that also, easily boosts that result, add a 3.73:1 rear gear ratio and a 3200 stall converter if its an automatic transmission and it will preform like a totally different car, ID expect more like 60-70hp and 60 more ft lbs at an absolute minimum PLUS with all those component changes, depending on the components used, a more radical hydraulic roller cam in a 10:1 compression 383 could certainly boost results much higher doubling your horse power from stock is certainly obtainable as a goal

    ok lets keep this rather basic, on a $3000 budget Id go this route, now obviously you could make a bit more horsepower with higher dollar parts but I think a combo like this should provide decent value, in increased responsiveness and acceleration, over the stock engines power level for the money spent.
    the stock engines make a bit over 205 hp
    http://www.vettefacts.com/C4/1984.aspx
    many 1984 cross fire corvette owners will brag about the low rpm massive torque the original cross fire engines have, but the truth is that the intake manifold, cylinder heads cam and even the original throttle body's and the fuel pump that supply those throttle body's are all nothing short of pathetically restrictive compared, to whats currently available and rather easily acquired and can be used to upgrade the original engines meager power level to something that's far more robust and effective.
    keep in mind you don,t need to start converting the engine to some totally different high rpm small block that spins at 7000 plus rpm, the original concept of the cross fire intake design with its long runner design was and is to maximize the low and mid rpm torque, but in the last 31 years a great deal of improvements in component design and new parts have become available, the renegade intake design is specifically matched to that lower rpm power band, but to take full advantage if the increased flow rated a slightly longer duration cam, much better heads (but keeping a rather effective 175cc-195cc port size) and swapping to a 3.54:1 or 3.73:1 rear gear to move the whole power band up about 800 rpm-1200 rpm higher and extend its upper rpm effective reach about 1000 rpm, from the original 4000 rpm-4500 rpm too, the now available 5000 rpm-5500 rpm ,while still maintaining and even increasing the available torque and instant responsiveness of the original design is not only easily accomplished but can produce rather amazing results, but you will need to look at the concept as a combination of matched parts that are well designed to work together,each boosting the other components effect on the wholes NOT the random swapping in a few better performing individual components.
    the change in cylinder heads,intake, cam, rockers and the rear gear ratio that allows the car to maximize it higher torque and horse power potential will be very noticeable in the drives seat, the heads and cam, intake and gearing all maximize that 2000 rpm-5000 rpm that will be used the vast majority of the time on a street driven corvette.
    A combo like this will produce a nice boost in performance, but before you ask, no you can,t mix & match or only install part of the combo, it won,t work to near its full potential unless all the parts are correctly installed and the cars engine adjusted and tuned to take full advantage of the increased air flow,and higher effective average useful rpm band

    the renegade intake is a good value

    http://www.ecklerscorvette.com/corv...nifold-crossfire-injection-1982-and-1984.html
    $544.99 ea.
    , its worth about 30 hp over the pathetic o.e.m cross fire manifold
    your stock cylinder heads are very restrictive



    HEADS
    http://www.summitracing.com/parts/pmx-2169?seid=srese1&gclid=CMXvk734wsgCFQmOaQodSDcOVQ
    $843.00(easily 35-40 hp if used with the cam and intake)

    OR
    http://www.summitracing.com/parts/tfs-30410001
    OR
    http://www.summitracing.com/parts/drt-127121/overview/
    or
    http://store.speedmaster79.com/p-50...-hydr-r-complete-aluminum-cylinder-heads.aspx
    or
    http://www.profilerperformance.com/racing/cylinderheads/sbc-23-degree
    )



    CAM
    the crane 114132 cam is the largest Ive found that works reasonably well with the basic OEM THROTTLE BODY INJECTION
    http://www.summitracing.com/parts/crn-114132 (also worth about 20-30 hp)
    $225.10
    OR
    http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=119&sb=2


    TIMING SET
    http://www.summitracing.com/parts/clo-9-1100/overview/
    $34.97 timing set, yours is without doubt in need of replacing


    http://www.cranecams.com/product/cart.php?m=product_detail&p=23790

    1.6:1 ratio ROLLER ROCKERS
    http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&Ntk=all&Jnar=0&itemPerPage=60&Ne=1+2+3+13+1147708&searchTerm=555-20105
    $237.99 (almost required to maximize the head flow and worth 12-15 hp in reduced friction and increased lift at the valve)
    your up to about $1900 at this point, youll need another $80-$100 in sealants and gaskets, you may be able to reuse the push rods but check the rocker geometry


    http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
    spend the rest on a DANA 3.73:1 rear gear ratio and its install cost
    the combination of these parts will produce what your looking for, a noticeable increase in performance, if you don,t get ALL the parts it won,t work nearly as effectively

    [​IMG]
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    [​IMG]

    the milder cam (cranes 114122) is easier to tune and will still give you a noticeable boost in performance, of about 20-25 hp, over the stock cam, but its also not going to give as much power over about 4500rpm as the slightly longer duration version (crane 114132)
    the scorpion 1.65:1 ratio rockers, or the 1.6:1 Jegs rockers have almost no effect on the idle characteristics , as they don,t do much to the duration or LCA. just increased valve lift and on these mild cams that extra lift helps

    [​IMG]
    [​IMG]
    the forged steel rockers generally clear in most application if the short nuts are used

    WHILE THESE ARE RATHER EXPENSIVE VALVE COVERS THEY HAVE ADVANTAGES THAT I THINK MAKE THEM WORTH THE COST
    http://www.summitracing.com/parts/pro-141-913
    [​IMG]
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    [​IMG]

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    READ THE LINKS AND SUB LINKS
    viewtopic.php?f=52&t=126&p=1193&hilit=ratio+rockers+louis#p1193

    viewtopic.php?f=52&t=181

    http://garage.grumpysperformance.co...s-and-valve-cover-install-info.946/#post-1615

    http://garage.grumpysperformance.co...g-rocker-ratios-and-the-effects.126/#post-156


    useful related info


    viewtopic.php?f=44&t=38

    viewtopic.php?f=52&t=5078

    viewtopic.php?f=52&t=181

    viewtopic.php?f=50&t=428

    viewtopic.php?f=69&t=3814

    viewtopic.php?f=69&t=519

    viewtopic.php?f=69&t=7804
     
    Last edited by a moderator: Sep 6, 2016
  4. grumpyvette

    grumpyvette Administrator Staff Member


    HERES SOME PLACES TO FIND ADDITIONAL INFO AND SOME USEFUL TIPS

    drop back to the basics of fuel spark timing , valve timing and compression

    1) whats the compression NOW and check MORE than just cylinder #1
    http://forum.grumpysperformance.com/viewtopic.php?f=50&t=10623

    2) verify TDC
    http://forum.grumpysperformance.com/viewtopic.php?f=52&t=966

    3) verify your getting fuel pressure
    http://forum.grumpysperformance.com...&hilit=balance+throttle+body+manometer#p39710

    4) learn how to adjust valves
    http://forum.grumpysperformance.com/viewtopic.php?f=52&t=196&p=231#p231

    5) learn how to degree in a cam
    http://forum.grumpysperformance.com/viewtopic.php?f=52&t=90


    6) timing
    http://forum.grumpysperformance.com...80&p=26610&hilit=+dropping+distributor#p26610

    http://forum.grumpysperformance.com/viewtopic.php?f=50&t=54&p=67&hilit=dropping+distributor#p67

    http://www.thecubestudio.com/CrossfireT ... sIndex.htm

    http://crossfireinj.5.forumer.com/

    http://garage.grumpysperformance.com/index.php?threads/refresh-1982-crossfire-vette.14173/
    geekinavette posted this

    "First things first...retrieve the ECM code(s). This can be done with a simple paper clip or by purchasing a OBD1 (On Board Diagnostics, 1st generation) code scanner. To use a paper clip, just use it to jumper pins A and B of the ALDL connector (mounted under the dash to the right of the steering column). Turn the ignition on (do not start!) with the ALDL jumper installed, and the CEL (Check Engine Light) will flash stored codes. The first code will always be 12 (no Distributor Reference Pulse...or in other words the engine is not running). To display a code 12 the CEL will flash once (1), then pause, then flash twice (2), then a longer pause, then repeat this process two more times (every stored code is presented three times). After the last code 12 is presented, it will pause a little longer and display any other codes that are stored in the same manner.

    Some definitions...

    TBI:
    Throttle Body Injection
    As ex-x-fire mentioned...a "wet flow" system, which means that fuel AND air flow through the intake manifold (as opposed to a port injection system which injects fuel directly at the cylinder, so only air flows through the intake manifold). The crossfire system uses two Throttle Bodies, each feeding opposing sides of the engine (thus the term "crossfire"). Some TBI systems use a single "dual barrel" throttle body, with two bores and two injectors, but all within one housing. Many consider TBI to be somewhat of a "hybrid" system between a carburetor and modern port fuel injection systems.

    ECM:
    Electronic Control Module
    Also referred to often as the "computer"...which is really what it is, albeit a very slow one.

    MAP sensor:
    (intake) Manifold Absolute Pressure...reported to the ECM in Kpa (and being a physics professor you already understand the significance of the word "absolute" here. Yes it is just a basic absolute pressure transducer). Manifold pressure is directly proportional to engine load.

    TPS:
    Throttle Position Sensor.
    Nothing more than a potentiometer between a fixed 5V and ground with the wiper lead reporting a voltage to the ECM that is directly proportional to throttle position. The adjustment of this is important so that the ECM can detect idle as well as WOT (Wide Open Throttle) conditions (as well as other conditions, but these two are important). The TPS mounts to the driver's side TBI unit, actuated by a lever connected to the throttle shaft.

    CTS:
    Coolant Temperature Sensor
    A simple thermistor used to provide engine temperature information to the ECM. (not to be confused with the temp gauge sending unit...yes they do the same thing but these are two separate sensors).

    IAC:
    Idle Air Control.
    This is a stepper motor mounted to each throttle body with a tapered cone plug attached to a lead screw. There is an air passage that bypasses the throttle bore (kidney-shaped hole on the top of the throttle body base), the IAC motor will extend or retract this "plug" to control how much air is allowed to bypass the throttle bore. This is used to control idle speed mostly, and is also used as a "stall saver" device.

    O2 Sensor:
    Just that...a device that measures oxygen content in the exhaust stream, used by the ECM (in addition to other sensors, like MAP, CTS...etc) to control fuel flow to the engine.

    ESC/EST:
    Electronic Spark Control/Electronic Spark Timing. Modern-day equivalents of the old vacuum operated spark advance.

    FPR:
    Fuel Pressure Regulator
    In contrast to a carburetor, fuel injection controls fuel delivery by pulse-width modulating a solenoid inside the fuel injector. How much fuel is delivered is determined by how long the solenoid is engaged in combination with fuel pressure. Obviously higher fuel pressure will deliver more fuel for a given pulse width. You can see here why fuel pressure is very critical in any fuel injection system. When checking fuel pressure it is very important to not only check pressure at idle, but under engine load also. The crossfire system is a serial plumbed system...fuel flows through the first throttle body (passenger's side), then to the second throttle body which contains the fuel pressure regulator. The stock injectors are rated at slightly different flow rates to compensate for the small amount of pressure drop between the two injectors (inherent in any series system), so if the injectors are removed for any reason it is important that they be replaced in the original locations.

    The term "dual plumbing" probably was referring to the fact that the crossfire system uses two independent throttle bodies...each with its own fuel feed/return as well as IAC valve (where as the "dual barrel" setup just has one fuel feed and IAC valve). However as with most dual plumbed systems, it is NOT a parallel plumbed system.

    There's no mystery to it...all of the laws of physics apply. I would not go the route of just buying stuff and replacing it...all that does is waste money and you won't really learn anything, and likely you won't fix anything either. There are items that wear out that manuals and "normal" repairs aren't going to cover. However with that said...a Factory Service Manual is an invaluable tool.

    Again...get those ECM codes! You have to start there.

    Some other nuances specific to the crossfire system...

    As mention in the previous post...fuel pressure! The stock '82 and '84 fuel pumps are notorious for falling short under heavy engine loads...they just can't deliver enough flow to maintain the required 13-14psi of fuel pressure. (yes the FSM states 10-13, but there's enough experience out there that will agree that 13-14 is really what is needed). A common "upgrade" is to swap the stock pump with one for a TPI (Tuned Port Injection) '85-'89 or so Vette. The TPI system requires more pressure, so the pumps are inherently designed to deliver more flow so as to maintain correct pressure. You will not effect pressure by upgrading to a higher flow pump, the Fuel Pressure Regulator takes care of that.

    Throttle Body Balance! Being independent throttle bodies, they MUST be balanced! One item that tends to wear out and severely upset this balance is the throttle shaft bores. You can do a quick check by just feeling how much movement there is of the throttle shaft within the throttle shaft bores. This "play" allows the throttle plates to move around, and it takes very little of this movement to upset the balance between the two throttle bodies.

    Vacuum Leaks! The intake plenum "lid" is notorious for developing vacuum leaks...not to mention old and cracked vacuum lines.

    These are probably the most common ailments of the crossfire system that effect driveability and reliability.

    Once again though...before any of this stuff is addressed...

    RETRIEVE THOSE ECM CODES! (yes it is important enough to yell) "
     
    Last edited by a moderator: Nov 21, 2017
  5. grumpyvette

    grumpyvette Administrator Staff Member

    a few useful wiring, and related diagrams for the 1984 crossfire corvette
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    this should be the 82 crossfire wiring diagram.. you might want to print it...

    [​IMG]


    grounds are at B6, B12, B13, A15 shows as a ground... i wonder.



    you will also want to print this one..

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    on the far right of this image blow.. is the EGR control valve.. note the ground wires for the fuel injection system are attached to the bolt next to it...

    there are more ground wires stashed around the car.. and ALL ARE IMPORTANT to be cleaned..
    [​IMG]


    here is a list of data stream from the 84/89 models. the 82 won't show this many...

    [​IMG]

    lastly... the coolant temp sensors that are screwed into the FRONT of the intake manifold.. NOT in the heads are horrible.. replace with an SU102 from autozone or wells.. they come with a pigtail also for 3 bucks more than just the sensor.. the only difference is the type of connector... Ask for it by part number.. as they will try to sell them to you individually.. for double the money.. hmm..

    lastly... take off the distributer cap... expose the coil.. also .. examine it for signs of high voltage leaks from the sides...

    take a bright flashlight and check the sides of the pickup coil for signs of broken magnets in the stack.. the thermal soaking these get under the corvette hoods is tremendous.. if you have to pull the distributor.. please preset the crank so the rotor is pointing in the proper direction and the reluctor tips and the pick up coil tips line up perfectly without going past and needing to turn the crank backwards... then look at the timing marks.. where do they line up.. this can save a LOT of time... as they are a PAIN to get the distributer out and in.. and dead stick timing it works great...

    sorry if i have bombarded you with info... i went to GM training school on feedback carbs and these throttle body fuel injection and also port fuel injection systems..

    if you get in trouble.. check your private message...
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    Post Reply
    waynep712222
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    Moderator
    Posts: 122
    Joined: 03/13
    Posted: 05/19/13 06:11 PM

    these images are for the 84 models. but are almost identical to the 82 models.. 82 models used an earlier computer than the 84s did..

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    su102 coolant temp sensor kit

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    this is probably an 84.. i don't think the battery is in this location.. i usually work on C4 versions.. not the slightly earlier 82 crossfire versions...

    please look at all the ground connections that you have... and they ALL GO TO DIFFERENT circuits.. they all have to be intact...

    [​IMG]



    Read more: http://forums.superchevy.com/super-...k/crossfire-injection-problems/#ixzz40kg5MK2D

    http://garage.grumpysperformance.co...sfire-vette-won-t-run-right.10096/#post-39656

    http://garage.grumpysperformance.com/index.php?threads/got-a-cross-fire-corvette.640/#post-25768

    http://garage.grumpysperformance.co...ng-tpi-crossfire-or-lt1-vette.1401/#post-9259

    http://garage.grumpysperformance.com/index.php?threads/c4-c5-corvette-trouble-codes.2697/#post-7017

    the symptoms sound like a defective sensor or fuel pump or fuel pump relay, but read through the links it will prove useful.
    as is true with many questions here theres a few related threads that may hold the answer your looking for in the links and sub links
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    http://garage.grumpysperformance.com/index.php?threads/ecu-functionality.10946/


     
    Last edited by a moderator: Jun 1, 2017
  6. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    step back and consider what your goal might be and your budget, then ask yourself if you want the corvette to run better while you maintain the basic original cross ram dual throttle body induction?
    or are you more concerned with getting the corvette to run considerably better and far less concerned with maintaining the original look in the engines intake design?

    we are all forced to work on limited budgets, but if your going to maximize a cross fire engine combo...
    the most restrictive components are the stock intake cylinder heads, exhaust system, and cam
    Id suggest you replace the intake with that renegade, intake and I do at least some port and runner clean-up port work,
    http://www.ecklerscorvette.com/corv...=25-324816-1&gclid=CLS6s6-l_NMCFYMSgQoddVYHsg

    Id suggest you call AFR and brodix about cylinder heads in the 180cc-200cc range
    the key to good power is in good heads maximizing the mid rpm air flow and a cam that will match the intake and head flow characteristics, you might also consider a 383 stroker assembly to maximize low speed torque.
    (its a very cost effective way to boost torque and hp an easy extra 40 ft lbs and 45 hp in most cases)


    http://www.airflowresearch.com/195cc-sbc-street-cylinder-head/
    http://brodix.com/heads-2/small-block-chevrolet-compatible-heads/ik-series
    Id suggest getting the static compression near 10:1
    Id strongly suggest you replace the exhaust system with a 3" and (X) pipe design with low flow restriction mufflers
    http://www.melrosecorvette.com/1984-1985-l98-corvette-header-system/

    and add full length headers
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    keep in mind that a properly designed exhaust system and headers goes a very long way towards increasing the efficiency of the intake manifold and head flow , and remember that the better the heads and the more effective the exhaust scavenging the less duration the cam used will require!
    Id suggest a mild hydraulic roller cam and use of quality roller 1.6:1 ratio rockers
    Id be looking for something in the 215-220 duration on the intake at .050 lift, call and get suggestions from crane, crower, erson, etc.
    the basic intake design and port config of that renegade intake design will limit the engines power band to near 2000 rpm-6000 rpm so a longer duration cam will mostly reduce lower rpm torque

    http://www.cranecams.com/product/cart.php?m=product_detail&p=24189
    https://www.crower.com/camshafts/ch...ft-hyd-roller-cam-small-base-circle-4120.html
    Id suggest a 3.73 rear gear ratio
    Id suggest a 2400 rpm stall converter
    these two drive train mods maximize the cars ability to use the power produced



    carefully reading through
    these links and sub links will help
    ITS GOING to be well worth the time and effort

    http://garage.grumpysperformance.com/index.php?threads/renegade-intake-for-cross-fires.2796/

    http://garage.grumpysperformance.com/index.php?threads/1984-fuel-pressure.11776/#post-55675

    http://garage.grumpysperformance.com/index.php?threads/got-a-cross-fire-corvette.640/#post-50502

    http://garage.grumpysperformance.co...lf-the-time-starts-and-dies.11187/#post-50245

    http://garage.grumpysperformance.com/index.php?threads/1984-crossfire-vette-won-t-run-right.10096/

    http://garage.grumpysperformance.com/index.php?threads/tweaking-a-350-383.13087/#post-68195

    http://garage.grumpysperformance.com/index.php?threads/what-to-look-for-in-a-good-engine-combo.9930/

    http://garage.grumpysperformance.com/index.php?threads/383-information-overload.11137/

    http://garage.grumpysperformance.com/index.php?threads/matching-parts-and-a-logical-plan.7722/
     
    Last edited: May 19, 2017

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