Looks like I've blown a head gasket on the 1986 Trans Am. Low oil pressure, weak power, and brown foamy coolant.

So thinking about the options... maybe I could use the opportunity to find a decent 350 SBC - even a crate motor - and toss the TPI system right on top of it. Is that way too simple?

I've already been thinking about the LS swap but then it's ECU this, throttle that, transmission another thing. Thinking about what would be a bit of an upgrade for not a lot of money or hassle. Pull accessories, pull engine, put new engine in, attach accessories, drive. That sort of thing.

Thoughts?

 

You will need to get 22#hr injectors. As well as have your computers chip (memcal) reprogrammed.
Depending on the year of the Crete motor you might need to elongate the center four intake holes.

 

Thanks, Tuned Performance. Injectors shouldn't be a big problem. Not really sure who's doing programming on these old ECUs these days. On the intake holes having to be elongated, you mean drill them deeper? Not use shorter bolts?

 

The bolt pattern on the center four holes are different angles 72 and 90.


If you need programming assistance you can send me a pm.

 

OH! I see. OK, thanks. Can you tell me what angle the LB9 is (or where I should find that) so I can use that when I'm shopping? If I go that route, I'll let you know on the ECM for sure.

 

I can recall what year 86 is . It might be 90degrees and in 87 was 72 I think.

 

Pretty sure the transition occurred in 87.

 

Looks like I can always get the intake manifold for bolting TPI to Vortec heads. And wiring harness should stay intact, right? If I'm keeping all the accessories. I think I would have more problems putting L98 into the LB9 car because the harnesses are backwards to each other in places.

 

If you get the Vortec TPI manifold, you have to use Vortec heads. They're not interchangeable with previous years.

 

Thanks ULTM8Z. I got that. My line of thinking is that since a lot of the crate options (long blocks) are coming with the Vortec heads. So if I want to put the TPI on the new engine, I'll need that intake from Scoggin-Dickey that the factory plenum should bolt right onto.
https://sdparts.com/i-23896057-sdpc-...baseplate.html

 

Drive a stock LS1 F-body.
Drive a stock L98 F-body.
Proceed as you see fit.

 

But a Vortec crate motor will not be a stock L98. Also still a LOT more expensive to do an LS swap - more expensive crate engine and modifications required to do so.

Not that it isn't a good idea, but it will cost more. And a built Vortec crate engine will make similar power to a stock LS1.

GD

 

Well... yeah. Obviously a stock LS1 car is going to be a lot faster. I get that. But I had a 4th gen, and just don't like them as much as the 3rd gen cars. So this is about driving a 3rd gen, not which is superior. Appreciate your feedback, though.

 

I'm laughing because us long time members seem to just cut to the freaking chase nowadays lol.

You want my thoughts OP? If varying ECM's bother you, then scrap the LS swap idea. If you're not going to forge the engine, then right there is your limitation in terms of horsepower. Any SBC can get you to that number when built properly; it's air, fuel and spark, nothing's changed. If horsepower isn't the name of your game, then slap a head gasket on the 305 and run it like that. If you want horsepower, than you will need 30# injectors to see 400 horsepower (in a V8) safely regardless which engine you run because we calculate horsepower via fueling. So ask yourself what your long time goals are, and maybe then everyone can help you better...

- Rob

 

Thanks, Rob. I get it. We're cool.

Long term goals? Have a fun & reliable street machine. I have this car and a 1990 L98 (350) car. If I could make this car get motivated like the 90 then I'd be a happy camper. Think of it like a "what if they sold a Trans Am with a 350 in 1986" scenario.

We're cruising or driving to work with this. With the AC blowing. We're not taking it to the track on the weekend.

If I wanted to get stoopid with swaps, I'd yank the drivetrain out of a Nissan Leaf. That car weighs about 100 pounds more than the Trans Am and does 0-60 in 7 seconds. More than a full second quicker than the Trans Am did when new. I bet that'd turn some heads at Cars & Coffee.

 

An L31 Vortec long block with a Vortec TPI base sounds like a good fit.

 

Thanks for that. Good call, as they're available from junkyards around $500. Just need the ~$300 manifold, I guess.

 

I am attempting this feat as well in my restoration but I am being told by BluePrint, Summit Racing, JEGS, etc that I can not simply put my 305TPI intake on a Vortex Head 350 motor and change the injectors. They are saying even with a reprogram of the computer the parameters of the ECM are so narrow it will not run properly. Is this the case?

 

You will have to at minimum reprogram the memcal to 350 parameters and change the base to a votec pattern if you are using vortec heads. No idea what a vortex head is.

 

I appreciate the response. but if I change the intake to a FAST type TPI setup that is compatible with the Vortec heads, the stock ECM (if reprogrammed) would be able to support the changes?

 

Reprogramming the memcal you can easily support the changes. What intake are you referring to. The only vortec base for tpi is edelbrock or scoggin dicky.

 

 

First maybe ?

 

 

It's this the case? A Scoggin Dickie lower with stock upper will not support 350 horses? I'm being told that intake setup would choke the engine.

 

That is not the case. Vortec heads change the equation, but aside from that the 305 TPI and 350 TPI are clones. The real differences are the injectors, knock sensor, and programming. If you can get a TPI fit to the Vortec heads it can be made to run fairly easily. The caveat is that the speed-density systems will be more appropriate only if the extended timing and fuel tables are used. MAF systems might struggle with higher air flows and metering fuel properly. It's been covered hundreds of times in detail in the DIY PROM section.

 

 

If you want a direct drop and use all your stock TPI stuff and could just run a stock 350 TPI chip ATK makes a nice TPI crate motor the Vette guys use. http://www.high-performance-engines....tte-p/hp57.htm