Standard TPI vs. LT1

Discussion in 'High Tech Retrofits' started by Ceth, Jul 31, 2006.

  1. SpeedAddict02

    SpeedAddict02 Veteran Member Lifetime Gold Member

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    thats what i thought, thanks
     
  2. Ceth

    Ceth Veteran Member

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    Ok cool. I think I will look around for a junky LT1 z28 6 speed and probably keep it around and drive it instead of my 78, it should get better mileage. Then when I have some real money, I would fix the 78 and put the drivetrain in it. I think the 4th gens are ugly, but I like the drivetrain.
     
  3. Zee

    Zee Veteran Member

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    Wait a minute, before jumping on the LT1 bandwagon, lets think about a few things.

    First, with the availability of aftermarket heads for both engines, it is likely anyone contemplating either swap will be swapping heads as well. Or at least that would be my program.

    Second, the real performance difference between the two lies in the intake, cam and exhaust differences between the two given that you will be upgrading the heads. Either way, you are likely to be looking at a cam and exhaust change in addition to the heads so the difference there is zero.

    Third, the LT1 block is no stronger or weaker than the L98 block. The LTI was some well known issues with it's timing chain, gear driven cam, waterpump, distributor combo. This is an expensive area for the LT1.

    So, the only real difference by the time you do the typical head, cam and exhaust swap is the PITA TPI intake vs. the PITA LT1 front drive WP, cam and distributor. You can't convert the LT1's drive but you sure can swap out the TPI intake to either Holley's stealth ram or TPIS' mini-ram. Either one is likely superior to the LT1 intake. So in the end, I would give the edge to the TPI in the long run provided you are commited to changing the intake. If not, the LT1 has the edge.

    Now, given the above, the unfortunate truth is neither engine has a significant advantage over any other SBC other than being set up for hydraulic roller lifters and FI. With aftermarket FI's like Holley's stealth ram with Commander 950 and retrofit HR's, even that advantage may be minimal if you already have a SBC.

    Enter LSX. Yes it is expensive and more difficult to swap but where else are you going to get an aluminum six bolt block, nodular crank, decent flowing heads and decent flowing intake all in one swap?
     
  4. Ceth

    Ceth Veteran Member

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    One thing to consider Zee is when I build up this engine, I REALLY want to keep it smog legal. Thats why Im deciding between LT1 and L98, because I also have to "copy" their smog laws. I cannot use any random performance FI setup and throw it on the car. I basically have to copy smog from a car same year as mine or later. LT1 seemed like good for emissions. OBDII and dual cats and all that good stuff. Just seems like LT1 has more potential if I want to keep it smog legal. And I was looking at the heads, it seems some of the heads from the LT1 were aluminum and do not need to be changed, just ported and polished and can support some good power. A guy I know has an lt1 in his 95 and claims 380RWHP and 400lb torque. Ported heads, SLP intake, edelbrock 50 state legal headers, 1.65 rockers, slightly better cam. If you stroke it up you can get more power and they also offer superchargers, smog legal.

    LSx swap is not only INCREDIBLY expensive, but it seems like a much harder swap to do. I am confident I can do an lt1 swap with some time, but the LSx seems like WAY too much of a pain.
     
  5. Zee

    Zee Veteran Member

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    Good point about the smog issue. I have wondered how some are getting past it. I believe in my state if you register as an antique, you are exempted but limited by miles. At this point, I believe all of the 2nd gens qualify. I have no idea how they verify miles if they do at all. Nothing from stopping one from having a spare speedo laying around!!

    Anyway, my point was (subject to smog laws) the performance difference between the LT1 and L98 after typical mods are done is very little and similarly the difference between the two and any other small block is possibly even less if you already have a small block and just add FI. So to make the change worthwhile, for me, it would be either add FI to my small block or the LS1 and I don't eat for a year or start walking to work. I could stand to lose some pounds anyway.

    If heads, cam and exhaust are not in the picture, than I agree with you 100%that the LT1 represents an excellent choice as it is the best performing of the three in stock configuration.
     
  6. Ceth

    Ceth Veteran Member

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    Yeah with CA smog laws, I will always have to smog this car. I thought about how to make it work, and it seems kind of PITA. I was reading the guide on FI swaps someone posted. The best non-LT1 setup would probably be right before the LT1, which is 90-92 or so. L98 with roller cam and a manifold absolute pressure sensor instead of mass air flow sensor, if I read what he wrote correctly. And they use centerbolt heads, but most aftermarket heads I can use with centerbolt. And vortech makes centrifigul blowers for those cars too, smog legal.

    So basically the difference between a 90-92 set up vs an lt1 set up is kinda small. The LT1 is newer and some come with good alum heads stock which can be made to handle a good amount of power with porting and polishing. The block in my car currently is a weak 2 bolt, the factory 78 block and not very strong. Are both the l98 and lt1 4 bolt mains? Both can be stroked to 383's. Good thing about an LT1 is that it comes with a t56 from factory, which means I can find a combo for usually cheaper. Also LT1 with OBDII uses a dual cat setup. Im not sure if I can use an OBDI with two cats and still pass smog, and the thought of making my engine breathe through a single cat system makes me cry.

    What does everyone think? Its not so much what each can do in stock config but in how much I can upgrade it while still retaining its smogability.
     
    Last edited: Aug 9, 2006

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