FIRST intake LT1 build

Discussion in 'Engine: Repairs and Modifications & generally corv' started by pg92, Nov 5, 2015.

  1. pg92

    pg92 New Member

    I just became a member of this forum today and wanted to post my build. My car is a 92 LT1 corvette coupe with an auto trans. Last winter I pulled the motor and did the following mods:
    Freshened up the lower end (rings, bearings, gaskets, oil pump)
    Installed AFR 195 street port LT1 heads and stock LT1 intake and TB
    Lingenfelter 219/219 cam installed straight up and comp 1:6::1 roller rockers
    Updated timing cover and installed pin drive Dynaspark opti distributor with Bailey engineering box and 8 LS1 coils
    Cloyes roller timing chain set
    Electric water pump
    Exotic Muscle LT ceramic coated headers and obx exhaust with no cats
    Edge c2800 stall converter
    Mail order tune

    My next step is to install my recently purchased Dana 44 with 3:33 gears Trans Go shift kit and FIRST intake manifold I have laying around from a previous project. The car will be used a a daily driver and will see little track time if any. Just looking to build a really fun street car with tons of tourqe. I think the FIRST manifold will work well for my intended application. Has anyone here used a FIRST manifold on a LT1 or any car for that matter?
     
  2. Indycars

    Indycars Administrator Staff Member

    Sorry I can't help with the intake question, but welcome to the forum pg92, how did you find us?

    WelcomeAnim.gif
     
  3. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    you are aware that MOST FIRST TPI intakes are designed for first gen SBC heads and that the,
    LT1 used reverse flow cooling requiring a TOTALLY different intake base with LT1 cylinder heads as the coolant passage lay outs totally different right??
    [​IMG]
    does your intake look like this
    [​IMG]
    https://firstfuelinjection.com/products
    the base for the FIRST INTAKE is available in
    GEN1 VORTEC and LT1 configurations


    lets clear up what may only be MY confusion here
    [​IMG]
    FIRST GEN SBC HAVE COOLANT PASSAGES IN THE INTAKE AND HEADS
    [​IMG]

    LT1 ENGINES ROUTE COOLANT THROUGH THE BLOCK AND WATER PUMP NOT INTAKE
    [​IMG]
     
    Last edited: Nov 30, 2018
  4. pg92

    pg92 New Member

    Ya that is my intake. I will be drilling the gen 1 base to match the LT1 bolt pattern. Since the LT1 uses a dry intake the gen 1 base will have some visible unused cooling ports on top like the hole for the T stat. The coolant cross over ports cast into the intake will just go unused. Might look strange but should work ok.
     
  5. pg92

    pg92 New Member

    Yes sir that's exactly right.
    On a side note I found this forum doing a search on degreeing a cam and am sure glad I did. This site has tons of great info.
     
  6. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    yeah! lots of older more experienced members tends to have that result

    notice the short LT1 oil pump drive bolts under the intake to the block casting, these are available in metal or plastic, obviously plastic is weaker and there's NO HOLE IN THE LT1 INTAKE, for a distributor in most versions notice the full length mallory version is a direct distributor replacement REQUIRING the hole in the intake to be alined and bolted, into place
    THE first intake WILL REQUIRE A BRASS FREEZE PLUG INSERT WHERE THE DISTRIBUTOR NORMALLY MOUNTS TO PREVENT LIFTER GALLERY OIL LOSS

    https://firstfuelinjection.com/products
    the base for the FIRST INTAKE is available in
    GEN1 VORTEC and LT1 configurations

    [​IMG]

    [​IMG]
    [​IMG]
    get a set of intake gaskets that fit the heads and TEST FIT match the bolt locations on the intake, then look at the ports,
    lt1 heads use the vortec port lay-out the first intakes , uses the earlier ,the first gen port lay out, it mayor may not extend out and cover,
    a good machine shop can generally weld material and mill to fix that potential problem
    post pictures of the LT1 gasket on your intake manifold flange surface if you can


    next time you have access to the later vortec style intake gaskets (even old used ones) and a 1955-85 first generation cylinder head ,or bfirst gen intake gaskets and a vortec cylinder head, take the time to line up the bolt holes on the gasket and cylinder heads, I thing you may be rather amazed at the differences in port size and locations.
    http://www.chevyhardcore.com/tech-s...-1st-gen-heads-vs-vortech-heads-reader-guide/
     
    Last edited: Nov 30, 2018
  7. pg92

    pg92 New Member

    Ok. I'll post pics as soon as I have them. I did have the FIRST manifold set on my old long block and I remember it matching up ok but I will have to double check now. If it dosnt I'll weld the top up like you mentioned. I know people do that when using a lt1 intake on lt4 (larger port) heads
     
  8. pg92

    pg92 New Member

    Ok, I have attached pictures of the stock LT1 gasket on the FIRST base and the L98 gasket on the FIRST base. You can see where I will have to drill new holes to make the intake work on LT1 heads. Plugging the distributor hole is no problem and as far as intake ports go everything looks ok to me. I have posted this on another site and the general consensus is that I would be taking a step backwards in technology/performance going to a long tube runner intake from my current LT1. My thinking was by doing this I will gain more power (torque) in the power band that my car will operate in. I have 3:33 gears and don't want to go steeper if I don't have to because it will be a daily driver and see a good amount of freeway miles so added torque would help. Plus I already own it and think the LTR intake looks pretty cool.
     

    Attached Files:

  9. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    [​IMG]
    given the two choices the l98 gasket seems to be the better match here,
    at least the outer bolt holes line up and the coolant passages, and inner bolt holes on the lt1 heads being a non-issue they don,t count
    [​IMG]
    [​IMG]

    https://firstfuelinjection.com/products
    the base for the FIRST INTAKE is available in
    GEN1 VORTEC and LT1 configurations

    [​IMG]
    the main problem with the internet heros is that 99.9% rarely step back and do the math required to calculate if some modifications feasible or, have the hands on experience building engines to test and to verify results, or to have previously built something similar so they have a good basis for an opinion based on facts and that experience, and probably 98% are content to endlessly parrot what they see posted, previously, rather than thinking through the potential of a combo vs the problems, the changes made may cause or correct..
    stock tpi runners are about 1.47" circular cross sectional internal diam. (1.7 sq inches)
    the first design are about a 1.75 circular cross sectional internal diam. (2.02 sq inches)
    roughly a 20% increase in area.
    that alone suggests you could expect something close to a 20% increase in usable rpm range, if only the intake were upgraded, the stock LT1 engine made in the mid 350-370 plus hp range.
    I think the cam you selected is a bit milder in duration than I would have used, but thats your choice, and not a bad one, matched to that intake to maximize low and mid rpm torque
    you can do the math but having done similar builds in the past I think you can reasonably expect to gain a good deal more mid range torque with no appreciable loss in upper rpm power at all over a lt4 engine and if you read the links below carefully youll see several people built 500 ft lb and 500hp engines with modified tpi based engines, your combo easily has that potential if you get the compression and cam timing and exhaust scavenging all maximized with that intake and heads

    related
    http://garage.grumpysperformance.co...8mm-throttle-body-on-your-tpi.290/#post-22467

    http://www.rbracing-rsr.com/runnertorquecalc.html

    http://garage.grumpysperformance.co...ther-efi-intake-manifold-info.431/#post-48733

    http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46582

    http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

    http://garage.grumpysperformance.co...que-specs-for-l98-tpi-intake-components.8572/

    http://garage.grumpysperformance.com/index.php?threads/calculating-ideal-port-size.624/

    http://garage.grumpysperformance.com/index.php?threads/can-you-get-there-with-tpi.10494/#post-44299
     
    Last edited: Nov 30, 2018
  10. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

  11. slywuf

    slywuf New Member

    So how did that work out for you - putting the FIRST TPI on your LT1 ?? I also have a 92 Corvette and just came across an older FIRST TPI, and thinking of making that mod. Was it worth all the hassle of modifying the FIRST base plate? Did you achieve a noticeable difference in power? Let me know your thoughts and recommendations please. Thanks.
     
  12. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

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