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Engine SwapEverything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.
Hello- I bought this 1988 Iroc-Z with a swapped 350 long block from summit, TPI setup. I have the specs in the pics below. I am a noob and was looking for direction regarding whether this was a good setup. From my understanding it’s not a race engine (and I don’t want it to be), I would though like something with low end torque, not high end hp. Question the cam and heads. I have good power now off the line, but what would be better? New cam & heads, just a port/polish, I do know the transmission is a 700r4, it currently has 1400 stall and 2.72? gears. I am planning on updating this to 2400 and 3.42’s. I’d really like help though on the engine specs and what I can do to make this a snappy, bottom end street car. Thanks.
Vortec heads and a better cam is the short answer. In doing that you will need a new intake, tuning, etc. etc. You have a basic flat tappet truck engine in there now that doesn't make even close to the power a stock L98 made. I guess all this depends a lot on how much power u want and how much you want to spend.
Richard Holdener on you tube just did a segment with this engine and how it responds to upgrades. He does exactly what Dmccain recommends and adds a vortec top end.
Thank you! I figured these would be the best options for this engine. Is there anyway to keep the TPI as I hear these are better for torque?
if you are retaining the TPI set-up you will need a specific manifold base to match the vortec heads. That along with larger runners and plenum will give you the aggressive low end you are looking for. Seeing you have 2.73 gears a minimum 3.42 and posi is needed. I'd look at sourcing a used 4th gen unit to keep costs low.
EDIT: This is all assuming you get the combo tuned. Via, DIY EPROM tuning or someone reputable who can tune it in person, meaning not mail order.
Regarding the cam, since I have a flat tappet and would like a hydraulic roller cam and roller lifters, is there and "conversions" needed there, or is is a simple swap out? Do you know if my block can accommodate the roller lifters (since they apparently started using them post 87)?
I remember just a couple of years ago they were around $2000. They also made a Goodwrench Vortec crate engine around the same price. I can't find that one anymore either.
Oh, I agree. The one in my Camaro was purchased 3-4 years ago on Summit and it was only $1700 then. They discontinued it on Summit per this link and have a suggested block almost 2x the price https://www.summitracing.com/parts/nal-12568758 (which looks like the exact same setup)?
Yeah in 2020 (which is NOT the same as, say, 2000) that's really the only thing to do that makes sense. Subject to the unfortunate reality that, for TPI, there is exactly one intake you can buy, that will fit those heads. It's available (or was last time I looked?) from Scoggin-Dickey and from Edelbrock. Same part AFAIK. It's NOT cheeeeeeep, but it sure BEATS THE HELL OUT OF abuncha TBI crap that the TPI DOES bolt up to as-is.
You used to could buy a Stealth Ram for Vortecs but I think it's been discontinued. And of course it's not TPI, not that that's a bad thing, but it's just that much more money and effort required. I think TPiS had a MiniRam for Vortecs at one time too but I don't remember for sure anymore and don't know if it's still available either. Pickings are getting slimmer all the time for the traditional SBC; it's been supplanted, just like the Frod flathead was in the mid 50s, and people (and vendors) are abandoning it. There'll still be SOME things available for it for a long time yet, the Performer RPM and Holley SA carbs for example most likely, but those "edge cases" like TPI are among the first casualties.
In 2020 (again, different from 2000) I would NOT under any circumstances switch to a carb. Not least because, any "savings" will most likely get eaten up QUICKLY in the difference in fuel economy.
Your gears incidentally are probably 2.73. Remember, they're a RATIO, between 2 tooth counts; meaning, the only possible ratios, are ones that are composed of 2 whole numbers. The # on the pinion varies from around 9 to about 15 in most rears, including this one, with the low #s corresponding to higher ratios; and the # on the ring is usually between about 37 and 45. 2.72 isn't a ratio of any numbers in that range. Preference is given to prime #s on at least one of the gears; for example, 3.73 is 11 and 41. (both prime) 2.73 is 15 & 41. (41 is prime) 13 & 42 is 3.23. (13 is prime) And so on... 2.73 was the usual 10-bolt ratio in the base-model 350 drive trains.
Thank you for the gear explanation, makes sense! If that's the correct intake it's not as bad as I was thinking. Will just have to figure out cam and other internals.
I was running an L98/350 with a zz4 cam (stock TPI intake), a 2400 stall and a 3.27 gear and the car was an absolute blast to drive. -and the 89 ECM ran the zz4 cam with no problems and even passed NC emmissions back in the day. Mail order tune was NOT as good as the stock tune. I mention this not to suggest that you not tune the car, but simply that it'll run. ....add vortec heads and it would be all the better! That vortec TPI manifold isn't the greatest manifold in the world, but in the RPM range you'll be running, the heads/manifold will be a great improvement. Could it be better? Yes. Is it still worth it? -definitely.
I think the GM Vortec/L31 long block is about $2900. The SD/TPI manifold and cam of your choice. -just check the lift as vortec head valvetrain has limits. I think the ZZ4 cam woulda been a smidge too high for un-modded vortecs.
In fact....that very motor may still be available. Sold it to a (now friend) here on TGO and I'm not sure he ever installed it. Great combo. Loved that motor.
Priced about the same as the Vortecs (either through Summit or SDPC) but they are far superior in a number of ways. And no new TPI base required.
$960. Also not bad.
Now before I get burned here, I've only recently learned about the AFR Enforcer. I've yet to do an A/B comparison but from just the hard parts alone included on the AFR such as screw-in studs, guide plates and certainly better springs, they have a lot of value.
