a few cross fire tips

[grumpyvette]

Here are some of the more common things I've seen with the 1984 CrossFire system.
if your 100% set on use of a stock x-fire
http://www.turbocity.com/product_info.p ... ucts_id=20
theres parts available

http://www.technovelocity.com/chevyhack ... olish.html
read this also
viewtopic.php?f=32&t=1148

check out the flow chart
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

good info source
http://search.ebscohost.com/
code is library/library then put in the brand/year and model

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

theres a new intake thats supposed to be available soon, heres
info

viewtopic.php?f=32&t=640

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

http://garage.grumpysperformance.co...egade-intake-for-cross-fires.2796/#post-55208

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

heres more good info
* Coolant Sensor is faulty - the gauge gives a false sense that it's doing okay, but the sensor that the ECM reads is totally separate from the one the gauge reads! Pinging on acceleration during warmer runs are noticed. If in doubt, just replace the thing. The one the ECM reads is in the FRONT of the manifold - has two wires (black and yellow) going to it.
* Throttle Position Sensor is faulty; can give strange results. Bad idle, great high-RPM power. Always good idea to check this thing out. Uses a +5v reference to send voltage to the ECM. Neat trick: setup the output (center wire) to where it switches to full +5v with the flip of a switch. Makes the ECM think you're at full-throttle when you're not. (Good for acceleration with an automatic tranny, which is all the crossfires ever came with that I know of.)
* MAP sensor - this thing reads in the amount of manifold vacuum and sends out a voltage to the ECM. If it's not getting the correct voltage, you can get pinging real bad on acceleration at any temperature. Pull the wires off. If the idle improves, you have a faulty one. Replace it.
* Bad O-rings or filters on injectors. Turn the key, but don't start the motor. Have the aircleaner assembly off and observe the injectors. If they leak, replace the o-rings and injector filters. If they still leak, replace the injectors!
* Bad O2 sensor. Runs rich sometimes. Won't pass emissions for sure! Is suggested to replace every 30k miles or so. They cost around $25 and are a snap to replace. Not a bad idea to replace if you're going to get under the car in the first place. You can run a wire inside your car and read the voltage with a DMM to see what your air/fuel ratio is.
* Spark Plugs fouling.. often this is due to bad valve seals. One of my tricks is to uncover the plug electrode by "side gapping" the plugs.
* Knock Sensor.. I think this is my problem right now. The "Computer Codes" book said it causes light pinging during acceleration on light loads.

ok the first step once you buy a corvette is ALWAYS buy the matching shop manual,and get a v.o.m. meter and use the shop manual, it will have detailed wiring diagrams and flow charts, and use the search feature on the site
as an example lets assume you buy a 1984 corvette

http://www.helminc.com/helm/Result.asp? ... LAKTTP9VS4
very good
http://www.haynes.com/products/productID/264
fair
http://performanceunlimited.com/documents/plugsidegapping.html

read these threads

viewtopic.php?f=50&t=609&p=3174#p3174

viewtopic.php?f=36&t=2619

viewtopic.php?f=70&t=2700

viewtopic.php?f=3&t=325&p=397&hilit=+meter#p397

viewtopic.php?f=44&t=469&p=7163&hilit=meter#p7163

viewtopic.php?f=62&t=987&p=2395&hilit=+meter#p2395

viewtopic.php?f=50&t=785&p=1337&hilit=+meter#p1337

viewtopic.php?f=32&t=2697

viewtopic.php?f=32&t=1773

viewtopic.php?f=32&t=596

 

[grumpyvette]

there SIMULAR but not IDENTICALThe 1984 5.7L (VIN 8) engine is equipped with a Model 400 Throttle Body Injection (TBI) system, also referred to as the Cross-fire Injection system. This system consists of a pair of throttle body units which are mounted in front and rear positions on a single manifold. This arrangement lets each TBI unit supply the proper air/fuel mixture through a tuned crossover runner in the intake manifold to the bank of cylinders on the opposite side of the engine. This is the reason for the name "Crossfire injection". Each TBI unit feeds the cylinders on the opposite side. The front TBI gets the fuel from the fuel pump. The fuel then goes through a fuel pressure compensator, through a separate line to the rear TBI, then through the fuel pressure regulator then returns to the fuel tank.


Fig. 1: Cross-fire Fuel Injection fuel meter system schematic


the 1984 cross fire vetttes L83 engine has some of the worst OEM heads ever put on any corvette

• Horsepower: 205 HP @ 4,300 RPM
• Torque: 290 lb-ft @ 2,800 rpm
• Compression Ratio: 9:1
• Displacement: 5.7 Litre/350 Cubic Inches
• Cylinder Bore: 4.00 inches
• Stroke: 3.48 inches

As noteworthy as these features appeared to be on the surface, much of the L83’s potential performance was stifled due to GM’s use of restrictive, undersized ports for the Cross-Fire’s intake. These ports were only ⅔ the size of those on the Cross-Fire’s cylinder heads, and as a result, limited maximum flow to no more than 475-cfm.

As a product of this restrictive intake flow, the L83’s torque peaked at only 2,800 RPM, falling off sharply once reaching 4,000 RPM. According to GM, this level of restriction was purposely engineered with the intent of providing more usable street torque. However, many have theorized that this was no more than a ploy to increase fuel economy, in a bid to meet CAFE mandates.

Even with its limitations, the L83 produced 205 horsepower at 4,300 RPM and 290 lb-ft. of torque at 2,800 RPM, with a 9:1 compression ratio. The L83 equipped 1982 Corvette was capable of completing a 0-60 MPH pull in 8.1 seconds and posted 15.9 second times in the quarter-mile. While many perceive these figures to be mediocre at best, the 1982 Corvette still holds the distinction as being one of the fastest new American production cars during its given production year.


Each TBI unit has its own fuel injector which are controlled individually by the ECM. Each TBI has its own IAC valve, which operate together. A throttle rod connects the throttle valves together. A single Throttle Position Sensor (TPS) is used on the rear TBI unit only. Also, a throttle bore tube is located under the manifold cover, below each throttle valve to help in mixture distribution. The throttle body portion of each TBI unit has several tubes which supply a manifold vacuum signal required for the operation of related engine and emission control systems. A vacuum port, located above the throttle valve is connected to the capped tubes used for on vehicle service air flow balancing, for final throttle valve synchronization. The amount of fuel delivered to the injectors is determined by an electronic signal supplied by the ECM. The TBI unit does not control, but is controlled by, the ECM. The ECM monitors several engine and vehicle conditions needed to calculate the fuel delivery time of the injectors. Delivery time may be modified by the ECM to reflect various operating conditions, such as cranking, cold starting, altitude, acceleration and deceleration. Each TBI unit has its own fuel injector which are controlled individually by the ECM.



Relieving Fuel System Pressure
CAUTION
Observe all applicable safety precautions when working around fuel. Whenever servicing the fuel system, always work in a well ventilated area. Do not allow fuel spray or vapors to come in contact with a spark or open flame. Keep a dry chemical fire extinguisher near the work area. Always keep fuel in a container specifically designed for fuel storage; also, always properly seal fuel containers to avoid the possibility of fire or explosion.

Place the transmission in PARK (automatic transmissions) or NEUTRAL (manual transmission), then set the parking brake and block the drive wheels.
Loosen the fuel filler cap to relieve tank pressure.
Remove the FUEL PUMP fuse from the fuse block in the passenger compartment.
Start the engine and allow to run until it stops due to lack of fuel.
Engage the starter (turn key to start) for three seconds to dissipate all pressure in the fuel lines.
Turn the ignition OFF, then re-engage the connector at the fuel tank or install the fuel pump fuse.
Disconnect the negative battery cable to prevent accidental fuel spillage should the ignition key accidentally be turned ON with a fuel fitting disconnected.
When fuel service is finished, tighten the fuel filler cap and connect the negative battery cable.
CAUTION
To reduce the chance of personal injury when disconnecting a fuel line, always cover the fuel line with cloth to collect escaping fuel, then place the cloth in an approved container for disposal.

 

[grumpyvette]

viewtopic.php?f=32&t=102

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

worth reading thru

a chain is only as strong as its WEAKEST LINK
and an engine will be restricted to its most restrictive component and the rpm range its filling its cylinders effectively in and burning the charge efficiently in..

just a reminder, stock heads , even ported won,t flow well enough to use the cam or intake potential. and stock,stall converters , 2.571-3.07:1 rear gears will be miserable to drive because you'll spend a huge amount of time out of the effective power band on the low side and won,t be breathing well enough to take full advantage of the upper rpm potential flow without the full package.

an intake that potentially flows 250cfm-300cfm , matched to stock heads that flow 200cfm , flows 200cfm and runs like a dog! and add a cam that's not opening the valves, or even one that is with restricted heads and you gain little if anything but a loss of low rpm power and no compensating gains with out the heads and gears/STALL to put you into the new higher rpm band where all the powers made, if the exhaust is restricting the scavenging your at a distinct dis- advantage that hurts power

yes you can swap to a alternate CARB intake or modify an intake to use the THROTTLE BODIES

don,t jump into ANY project without thinking thru your options and thinking thru your goals, if you want a mild increase in hp a simple cam swap and a low restriction exhaust and headers will work fine.
if you want a more extensive upgrade it requires thinking thru your goals and selecting components that allow you to reach those goals,at some point the stock components will be a huge restriction to further progress.
adding displacement and boosting your compression is one of the cheaper and less finicky ways to boost both hp and torque, without sacrificing dependability, so think about swapping the stock 350 with its approximately 8.5:1 cpr for a 383 stroker with about a 10;1 COMPRESSION RATIO AND A NEW CAM, AS THATS EASILY WORTH 50 PLUS HP OVER A SIMILAR BUT STOCK 350 SHORT BLOCK.
if you read thru the links and sub links earlier in the thread, theres a good deal of useful info, but to sum it up, the stock heads SUCK, in that those heads flow less than 200cfm in stock form, the stock cams restricting power to the 1000rpm-4500rpm power band,and the x-fire intakes a total restrictive disaster, yes it can be improved, but not enough to make the work worth the results, in my opinion.
add to that the restrictive stock exhaust and your beating a dead horse,you can of course do that but after working on at least a dozen cross fire projects and seeing the results of beating that dead horse vs swapping to other components its a total no brainer in my opinion to upgrade the intake, heads and cam and exhaust, rather than be saddled with the restrictive components, limitations.
your only realistic option, is to install a better cam, better flowing heads and a totally different intake,and headers with a low restriction exhaust, if you want to keep the stock gearing and look ( the crane 114132 cam,(auto trans) or 114142, (MANUAL TRANS) and the offy intake and some decent heads , like brodix,trickflow or AFR 180cc-195cc heads would be a good idea, you can easily boost hp an additional 100 plus with those four changes.
if your willing to swap to a higher stall speed converter and a 3.73 rear gear your cam selection options expand far further, and your potential power range increases, swapping to a carb and better intake is usually even cheaper and easier


http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/calcafhp.php

http://www.wallaceracing.com/runnertorquecalc.php

http://www.wallaceracing.com/dynamic-cr.php

http://www.chevytalk.org/fusionbb/showtopic.php?tid/131229/

 

[grumpyvette]

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 with CUSTOM LID removes that restriction
THE EXTREMELY RESTRICTIVE STOCK INTAKE

every time I hear that (BUT THE 1984 MAKES GOBS OF TORQUE) I want to point out a few facts

http://www.stingray.nu/tips/tech84.htm

http://coloradohotrodparts.com/Offenhau ... Y-5901.htm

right from Chevy (1984 vette)
Brake horsepower 205 @ 4200
Torque 290 lb-ft @ 2800
Comp. Ratio 9.0:1



right from Chevy (1991 vette)
Net HP @ RPM 245 @ 4000
Net Torque @ RPM 345 @ 3200


heres an example of what CAN BE DONE WITH THE CORRECT COMPONENTS

http://www.airflowresearch.com/articles/article031/A-P1.htm

custom lid SY1

compare the ports, the SY1 flows about 270cfm

<b>"A MODIFED EDELBROCK SY1 WITH CUSTOM TOP MATCHED TO 190CC AFR HEADS CRANE 114142 CAM -- AND add a 383 high compression engine kit"

b>
BTW Ill save you the math, youll 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 thats UNDERESTIMATED for those listed changes

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

offy
MORE USEFUL INFO

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

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

unless your rich or hopelessly masochistic get a SY1, base or a similar intake with larger ports and runners

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

Still think you should look into the SY1 Edelbrock intake(pictured above), there is only so far you can go with the CFI intake


the point IM trying to make, is not effected by the exact rpm point where peak hp or torque occurs in the rpm band, in the stock engine, or if you can modify the stock intake to produce 250hp-even eventually perhaps 300-350hp with extensive mods, a larger cam, etc.,which while being an impressive improvement, is still far less than can be achieved, its that your effectively being restricted in your goal,by the use of the basically stock components, for higher potential hp gains to the point its beating a dead horse compared to the engine power potential with the much better parts that are readily available, if your thinking of using the stock heads,intake, cam or exhaust system , why restrict your gains to 300-350hp when 450-500hp are potentially available and require less custom port work, intake mods to achieve,
you would not attempt to run a 1000 yard race with your mouth duct taped shut so you could only breath thru your nose, so why would you restrict air flow thru your engine in a similar manor with the restrictive stock components?
keep in mind that (old saying)" a chain is only as strong as its weakest link"
having heads that flow 270cfm gains you not a bit of improvement if matched to an intake that flows 190cfm, matching an intake that flows 270cfm to heads that flow 200cfm gains you zero! having heads and an intake that potentially flow 250cfm at .600 lift but retaining a cam with .420 lift and a duration limiting your engine to about 4500rpm will be a huge restriction on its potential power.
having a transmission and gearing that forces the engine to shift at 5000rpm and spend most of its time in the 1200rpm-4500rpm band will hardly allow a set of heads and an intake designed to provide max effective power in the 3700rpm-6500rpm band to function anywhere near their full potential


THEY WILL NOT SUPPORT A LARGE INCREASE IN HP WITHOUT MASSIVE CUTTING AND REWELDING WORK,WHICH COSTS FAR MORE AND WORK FAR LESS EFFECTIVELY THAN AN SY1 SWAP WITH A CUSTOM LID

this is the port work necessary to get them to flow even as pittifly as a TPI

 

[grumpyvette]

THE OFFY base IS STILL CURRENTLY MADE, and can be adapted

http://stealthram.com/flowcomparison.html

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

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

http://store.summitracing.com/partdetail.asp?part=OFY-5903

the basic crossfire manifold is a HUGE restriction EVEN if ported to the max, the XRAM is nothing but a single plane carb intake with a mickey-mouse adapter to allow the TBI injection to be bolted on.

read thru this

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

either the OFFY or the SY1 intake base, with a custom top plate will be a HUGE improvement, easily able to support 500hp or more on a correctly configured engine with decent heads like the AFR 210cc or AFR 195cc

http://www.airflowresearch.com/210sbc_rh.php

and a decent cam like this crower

http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=00404&x=25&y=17

installed in a 10.5-11.0:1 cpr 383

but keep in mind youll need a 3000rpm stall converter and 3.73:1 rear gear to run those
keep in mind INTAKE HEADS AND CAM and COMPRESSION ALL must be upgraded to get full flow into the heads , so that the power levels your looking for can be achieved,and the stall and rear gear must be changed to use the significantly higher rpm power band effectively, but theres no comparing the results after the mods are correctly made, youll have well over 140 plus MORE hp,(plus) if you do things correctly

 

[grumpyvette]

" GRUMPYVETTE?
I was thinking about doing the x-ram since they don't make the sy1 anymore. I dont have much money. just put a side exhaust on it. how much would the 383 cost and how much hp would i put out?"
you can usually find USED SY1 intakes on EBAY for under $400

a 383 will generally make about 40hp and 40 ft lbs more than a similar 350 combo with the same parts and at about 300rpm lower in the rpm range.
cost depends on components used, if your working on a strict budget you could probably convert a 350 to 383 displacement , useing mostly your old parts where they will function for about $1000-$1500 or less some combos MUCH LESS

the most common 383 combo Ive used that got good results used 10:1 cpr and this cam, and 1.6:1 ratio roller rockers

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=114132&lvl=2&prt=5

in a 383 upgrade you can use stock gearing and be fine.
it will work with the stock computer and stock tq converter or the manual transmission.
Ive generally either used the trickflow or AFR heads , but the stock heads will function fine, youll just be down about 45-80hp from where the better heads would be.


heres some sources for parts ID RECOMMEND,

http://www.ohiocrank.com/chevsb_rotate.html

http://www.dougherbert.com/

http://www.adperformance.com/index.php?cPath=277&main_page=index

http://www.summitracing.com/

http://www.jegs.com/

http://shop.enginekits.com/osb/specials.cfm

http://www.lewisracingengines.com/

 

[grumpyvette]

THE CAM THAT WE GOT THE BEST RESULTS FROM WITH THE CROSS RAMS IN THE OLD DAYS WAS THE CRANE 110921,(IT USED A DIFFERANT part NUMBER but the same specs then)

http://www.cranecams.com/?show=browseParts&action=partSpec&partNumber=110921&lvl=2&prt=5

but it really requires about 10.5-11:1 cpr MINIMUM and 11.5-12:1 CPR is IDEAL,and a 3.73-4.56:1 rear gear and a manual trans to work really well in a 302-327

btw
http://store.summitracing.com/partdetail.asp?autofilter=1&part=OFY-5893&N=700+115&autoview=sku

http://store.summitracing.com/partdetail.asp?part=OFY-5903


the offy versions still available

notice the crane cam has more lift and slightly less durration, and it pulls well lower in the rpm band and up to about 7500rpm in a properly built 302sbc

heres the factory race cam specs, it ran like crap under 4000rpm, and didn,t have any more hp up top,
270-968821
Factory ''Off-Road Special'' Camshaft
BluePrinted Mechanical Flat Tappet Camshaft
Lift: .493''/.512''
Duration @ .050'': 257°/269°
RPM Range: 4200-7000

 

[grumpyvette]