87 TPI 350 Swap

[Mike G]

Hi all,

 

I am looking to do a new SB and 700R4 for the Monte and have an opportunity to get a complete donor vehicle to work from. Its an 87 Corvette 130k mi on it with stock aluminum heads that I can get for under 2k. I was thinking about transplanting the L98 TPI and trans into the Monte after a rebuild on both.

 

I am looking to do the motor between 350 and 400 HP and would like to keep the TPI on it.

 

Is it possible to make that kind of HP with the stock TPI? Would I have to change the gas tank?

Should I use the factory harness and ECM?

Or should I stick to my original plan of a new ZZ4 and 700R4?

 

Thanks everyone!

[Ian]

Well it is a factory roller engine, rated for 240 HP stock. I would think it would be a good base to start with. You could use the stock ECM and wiring, but if I was going to do that kind of swap I would use a fresh wiring harness from someone like Painless Wiring... The stock ECM and wiring is going to have a bunch of "extra" wiring and also security settings. ERT has a similar setup in one of his cars...

 

Are you saying you can get the whole car for under 2K? If so you could part it out and recoup the expenses

 

Engine Base Engine RPO L98

Type V-8, 90-degree Overhead valve

Block Cast Iron Block with Aluminum Cylinder Head

Displacement 350 cid (5.7 liters)

Bore & Stroke 4.00" x 3.48"

Compression Ratio 9.5:1

Brake Horsepower 240 @ 4000

Torque 345 lb-ft @ 3200

Main Bearing five

Valve Lifters hydraulic

Fuel Supply Tuned-port induction (TPI) system

[Slaman]

I think the aluminum head vette motors made around 285 hp from the factory, so with some chip tuning and a mild to medium cam 350 hp should be pretty easy. The big thing you get with the TPI is low end torque, which is great for cruising around and stop light fun. My understanding is they run out of airflow around 5200 to 5500rpm in stock form.

Truthfully, I am not certian 400 ponies are possible with the stock TPI. With the aftermarket base and runners, 400 hp, sure. That being said it is much easier to do the swap with a complete car to pull from instead of piecing it together like I did.

As for the tank you can run an extrenal fuel pump but I would recommend an in-tank pump with baffels. Some people use the B Body tanks from late Caprices, Road Masters etc, but that requires some trimming on the frame and cutting the trunck floor.You can get an after market tank with the baffles and pump but they are not cheap. There is also a shop that makes an retro-fit option, look up tanks.inc for that one. Me I took the tanks inc concept and madified my tank awith some parts I traded.

As for the wiring harness.. That's up to you if you want to spend the money for a prefabbed one or modify the orginal. I modified an orginal because I'm on a pretty tight budget but seriously looked into a prefabbed one off e-bay for the ease of it and fact that it would be new.

Send me a pm if you want I have dug up some decent web sties to get info from on this swap and a forum for modifing the stock TPI.

 

Steve

 

Here is how I modified my tank;

The pump setup is actually out of a Turbo couple T-Bird.

And here is a shot of mine.

[Winston Wolf]

These guys were a pioneer in early TPI engine building. TPIS

 

I used some info from them on a 86 IROC back in the day. That 305 would kill 350's.

 

They also had a book back in the mid 90's that had some good info...not sure if you can still get it?

[monte70car]

Mike I would say upgrade to the 91 computer and harness, also with it being a 87 TPI it will have the 9th injector for cold starts. My choice on where to shop for TPI parts is aztpi.com got enough thing you could want. Also when you go to a bigger cam you will need a custom burn chip. The TPI swappers guide is a nice book to pick up as it covers the different fuel rails and the changes from the 87 to 91 TPI's, one system to stay away from is the cross-fire fuel injector. Here our little tpi vortec base intake stock 89 injectors, 89 Camaro fuel rails, 89 runners and 89 top intake. It takes a while to get the timing right as you unhook a wire set your base hook the wire up and the computer does everything else, with the 700r4 the computer will control when the trans locks and unlocks. Our TPI is a 355 which made 390 to 410hp on a single plane and a 600 Holley haven't had the fun time of testing the TPI do to wrong chip.

[Mike G]

Sounds great! Thanks everyone for all the info. I guess I have a lot of reading to do now. Now I need to figure out where to put the car when I get it.

[Andy's Auto]

Mike, not a tom of experience with TPI but I will share when pours out of my right ear.

 

I installed a 383 TPI crate motor in a customers 90 IROC around 12 years ago. It was a hoot. Had the HOT cam and the fast burn heads but would never pull much past 5500 RPM with the stock runners and hat. Earlier this year I talked him into doing the rear end and the intake.

 

Added the Edelbrock Hi Flo runners, hand ported the stock hat and added a Pro Products dual 58MM throttle body. Went to JET Performance and had them burn me a chip that would let me see the potential. Added 36 LBPH injectors, a Walbro 280LPH pump and went to town. Now 6700 is starts to drop power. The car is a fast. Like 11.67@117 fast with a Tremec 5 speed.

 

The only issue was the throttle body. When the car warmed up the throttle would stick. Tried two of them and finally went with a BBK unit. They put a coating around the throttle plates so they dont stick. Like an oak tampon, they would swell and stick.

 

Personally my next Monte build is gonna be an LQ9 6.0 with the Edelbrock intake that carries a stand alone ignition system. And I have the intake unused off another project.

 

Andy