L98 TPI any suggestions?

[MichiganJames]

How hard is it to do a tpi setup? any suggested threads. I am having a hell of a time locating what I want for drive train on my 54 with s10 frame

[1project2many]

Not too hard but some time investment. Can provide more tips later but busy, busy right now.

[Roadkill58]

wiring harness, ECM, and prom.

http://www.larryselectricsite.com/st...id=2&groupid=0


.

[roger55]

I bought this setup out of a '91 Z28 for $1,000 and put it in my '57 3200.



It came out of this creampuff with just 63K miles on it.. The guy bought just bought the car from an older man and decided to pull the L98 in favor of a LS1.



I cleaned it all up and painted it Chevy orange:



I fabbed an intake pipe for it:

[1project2many]

L98 is a great truck engine but it doesn't work well above 4000- 4500 rpm in stock form. Numerically high final drives aren't the best match for TPI. TPI was available with two control strategies, MAP and MAF. There are arguments for either side but if you're leaving the engine stock or doing mild modifications, MAF is generally easier for a guy that doesn't have a lot of electronics experience to install and get running. Corvette systems are a little different than Camaro systems and a Corvette engine will have a vastly different pully configuration than the Camaro / Firebird. Plenty of people can tune the TPI for custom needs so deleting systems or making small changes shouldn't be a problem.

Do you have specific questions?

[tmoble]

jeeze, the internet ate my reply

[58CameoAZ]

I have a L98 out of an 85 Corvette and will be in this same situation as you are asking!
i have the wiring harness out of the Corvette and not sure what i am getting myself into
as i have not crossed this bridge yet (Motor was complete with Automatic trans and Car was a running car before i Cannibalized the Vette) i have the rear suspension in the Truck and now am putting the front suspension in! Roger55 is a Wealth of information Here as he has converted his as shown!
Good Luck
Allen

[MichiganJames]

So in your guys humble opinion, would a 85 TPI be good to use? I would like a bit of power but nothing crazy. Im going for the driver cruiser or air.

I feel when my budget is larger and not needing to be spread out i would be fine to upgrade to LS later with a bit of ease, am I wrong?

[58CameoAZ]

I bought a Complete running 85 Corvette and when i was looking i was mainly looking for
the front and rear suspension, When i got this car it was in running condition and the motor only had 76K on it so it was like icing on the Cake in having the motor and trans for my Cameo project!
I just want a Cruiser and when i want the truck to get out of its way i can and after seeing Roger55 motor set up in his truck i pretty much knew that i wanted to go this route with my truck!
FWIW
Allen

[roger55]

Originally Posted by MichiganJames

So in your guys humble opinion, would a 85 TPI be good to use? I would like a bit of power but nothing crazy. Im going for the driver cruiser or air.

I feel when my budget is larger and not needing to be spread out i would be fine to upgrade to LS later with a bit of ease, am I wrong?

Yes I do. Even though it's older technology, it's still a very good engine and like was mentioned, a very good engine for a truck. I've had several. I had an '85 and '90 Corvette and put a TPI from a Trans-Am in a an El Camino SS. So this one in my '57 pickup is my 4th of these engines. These L98 engines make awesome power from idle to a little over 4000 rpm. After about 4,500 rpm, they fall flat.

To this day, I still think it's the coolest looking engine Chevy ever made.
You just need to get one cheap to make it worthwhile. If you don't get it cheap, then a later model 5.3 liter LS style engine starts making more sense. I've got $1,350 in my engine/transmission, harness and the reprogramming of the ECM.

However, if you are thinking about an upgrade later to an LS, I wouldn't do it that way. I'd go with an LS now. Look for a deal on a wrecked 5.3L truck from around the 2008 year.

[1project2many]

Comparing vehicles that are completely stock, I've always felt the '85 Vette TPI was a bit snappier than any other year. The cam is slightly different from later cams. When going through parts books you can see GM changed the cam in '86 but they superceded the 85 part number as the years progressed so if you ordered an '85 cam you ended up with a current production version that doesn't feel the same.

'85 has a unique computer only used on one year but there are tools that will allow some custom tuning for that ecm. For any serious modifications a computer change is very helpful. One advantage is that the '85 wiring is simpler than 86-89 cars.

During the swap, check the injectors for leaking (or just replace them). Hard to believe but there are *still* some early TPI cars running original style injectors that have a tendency to build up deposits which causes them to fail to close completely.

Provide a good, constant fuel supply, do a good job with the wiring, and you can have a strong and reliable engine. Match up your gears properly and you could see 18+ mpg in the truck.

[58CameoAZ]

Originally Posted by 1project2many

Comparing vehicles that are completely stock, I've always felt the '85 Vette TPI was a bit snappier than any other year. The cam is slightly different from later cams. When going through parts books you can see GM changed the cam in '86 but they superceded the 85 part number as the years progressed so if you ordered an '85 cam you ended up with a current production version that doesn't feel the same.

'85 has a unique computer only used on one year but there are tools that will allow some custom tuning for that ecm. For any serious modifications a computer change is very helpful. One advantage is that the '85 wiring is simpler than 86-89 cars.

During the swap, check the injectors for leaking (or just replace them). Hard to believe but there are *still* some early TPI cars running original style injectors that have a tendency to build up deposits which causes them to fail to close completely.

Provide a good, constant fuel supply, do a good job with the wiring, and you can have a strong and reliable engine. Match up your gears properly and you could see 18+ mpg in the truck.

I Find your words very encouraging!
Like i said when i bought my 85 Corvette i was just after the suspension but after driving this car and the condition the motor was in AND i was following Roger55's Build at the time! that was the deciding factor right there!
Didn't mean to high jack this guys thread tho but glad to here all the comments about this style motor.
Thanks
Allen

[roger55]

I had an '85 Corvette with an automatic and the G92 3.07 performance axle ratio.

I traded the car in for a '90 Corvette also with an automatic and same G92 3.07 performance axle.

In total stock form, the '90 had a slight edge on power.

However, after I had owned the '85 for a while, I upgraded to an adjustable fuel pressure regulator and upped the fuel pressure from 30 to 42psi. That made a noticeable difference.

I'd say my '85 with the upped fuel pressure ran identically to my '90 Corvette. After I bought my '90, I checked the fuel pressure on it with the stock regulator and it was already about 42 psi. The '85 was rated at 230 HP and the '90 at 250. I'd say most of that difference was that in the stock fuel pressure settings. Some of it could be in the cam. The '85 Corvette has a flat tappet cam and the '90 has a roller.

1985 Corvettes had cast iron heads and flat tappet cams. In mid-year 1986, they went to aluminum heads with center bolt valve covers. Starting in 1987, they went to roller cams and blocks with a 1 piece rear main remained that way through 1991.

In 1990, they changed from mass air flow sensor (MAF) to speed density. It is MUCH easier to set up the air intake for a conversion with a speed density setup. For this reason and the fact you get the roller cam, aluminum heads and the updated 1 piece rear main block, I would opt for finding a 90-91 Corvette or 90-92 Camaro/Firebird TPI engine. Don't dismiss the 305 TPI engine if you find one of those. They make good engines too. That's what mine is.

The older engines can be converted to speed density but it adds a little more complications to do. Best to start out with a 90-92 in the first place. I was elated to find the deal on the '91 Z28 engine and transmission that I'm putting in my '57 truck.

[tmoble]

yessir, that was a smoking deal.

If a guy is comfortable with a little wiring a Microsquirt EFI computer from DIYautotune.com can be used to run the EFI unless you've switched it to low-impedance injectors for some reason. About $300 and completely laptop tunable. You can even blutooth it to a tablet or phone. Phone display is really too small though.

Here's my reply that got lost somewhere out on the ethernet. Now that I see your build thread you may not need to answer.

re-reply to roger55:

Your TPI setup is really clean and neat, maybe the best I've seen. I'm starting a total re-build of my 57 with a TPI setup on a hand-built 355. I would appreciate it very much if you would be willing to answer a few questions.

What did you use to paint the TPI stuff? are the runners and plenum painted the same? did you prime with some aluminum type primer?

Do you have a regular small cap HEI under the cover?

the air intake tube you mention as fabbed, is it something a guy could buy or what did you fab it from?

the air filter, is the bulkhead fitting through the inner fender a commercially available thing? I've tried to google it but no luck.

the shield around the filter, is it available or did you build something?

I've already bought that VA condenser kit, looks good.

Thanks for taking time to answer.

[roger55]

Originally Posted by tmoble

re-reply to roger55:

Your TPI setup is really clean and neat, maybe the best I've seen. I'm starting a total re-build of my 57 with a TPI setup on a hand-built 355. I would appreciate it very much if you would be willing to answer a few questions.

What did you use to paint the TPI stuff? are the runners and plenum painted the same? did you prime with some aluminum type primer?

Do you have a regular small cap HEI under the cover?

the air intake tube you mention as fabbed, is it something a guy could buy or what did you fab it from?
the air filter, is the bulkhead fitting through the inner fender a commercially available thing? I've tried to google it but no luck.
the shield around the filter, is it available or did you build something?
I've already bought that VA condenser kit, looks good.
Thanks for taking time to answer.

Thanks for the compliments!

There is no paint on my intake, plenum or runners. That's what they look like after blasting with AH sized glass beads.



Yes, '91 L98's came with the small HEI so that's what's under there. Btw, Corvettes came with aluminum distributor covers and Camaros/Firebirds came with a plastic one. I painted that plastic cover with aluminum spray can paint and it matches the natural aluminum pretty well.

I am a believer in true cold air intake setups.
So, I did a lot of studying how I could fit one into the truck. It's pretty similar to the one I did for my Bel Air.

First of all, I need one specific bellows to make what I had in mind work. I did lots of looking at photos before I found this one that comes on ram air Trans Ams.
It cost me $60 and I didn't care for that but it was perfect.



I also found and purchased this Spectre air filter as it was a great size to fit inside the fender well behind the headlight.





I then bought a 3 1/2" straight exhaust pipe and a 90 degree elbow and welded them together. I then cut a hole in the passenger inner fender for it to pass through to the air filter.





In this photo, you can see that I reshaped the inner fender a little around the hole and also figured out how to route the upper radiator hose. I had to get another thermostat housing since the original one has a 1 1/4" outlet and I needed 1 1/2". I also bought a stainless 90 deg elbow to make it work. The lower hose was easy. It is just a 1 3/4" hose with a molded 90 deg bend.



Since the outlet size of the Spectre air filter is 4", I needed a step up adapter for the 3 1/2" pipe. I found an exhaust adapter that worked perfectly for that and welded it directly to the inner fender. So, I cut the long pipe and tie it into the adapter with a rubber connector.









Here you can see that there's tons of room inside the fender well for the air filter. I am thinking about plugging the outlet on the end and cutting a hole(s) in the front side of it so it will grab air from away from any water spray that the tire might throw.



I fabricated a support that I mounted to the shroud (using rivet nuts).





I didn't feel it needed to attach to the pipe but I did put a piece of rubber between the support and the pipe so it doesn't hurt the paint on the pipe.

I used silver base and and then clear on the pipe for a finish. The silver is code WA994L. It's used on several late model GM vehicles.

[roger55]

Another thing I want to mention here is exhaust.

I don't know for sure but I think the L98 exhaust manifolds on a Corvette engine would fit in a TF truck OK.

The exhaust manifolds that come on the Camaros and Firebirds will not. If you look at my photos, you can see that I opted for a set of ram horn style manifolds. They are new repros and are 2 1/2". The cost me $125 on ebay. 2 1/2" ram horns actually flow pretty well. I'd say they flow as well as any shorty style header. will. Shorty headers can be a problem in fitting a TF truck too. I tried a set and they would not.

[tmoble]

Thanks for taking time. I did find your build thread link and started going over it. Lots of info there. Now a permanent book mark.

[58CameoAZ]

Originally Posted by roger55

Another thing I want to mention here is exhaust.

I don't know for sure but I think the L98 exhaust manifolds on a Corvette engine would fit in a TF truck OK.

The exhaust manifolds that come on the Camaros and Firebirds will not. If you look at my photos, you can see that I opted for a set of ram horn style manifolds. They are new repros and are 2 1/2". The cost me $125 on ebay. 2 1/2" ram horns actually flow pretty well. I'd say they flow as well as any shorty style header. will. Shorty headers can be a problem in fitting a TF truck too. I tried a set and they would not.

Roger the exhaust manifolds on the 85 Vette are very similar to the ram horn type you have, and look like a small type of header, i think they will work out pretty well, that is my game plan anyway!
Allen

[1project2many]

I don't know for sure but I think the L98 exhaust manifolds on a Corvette engine would fit in a TF truck OK.

LAter tubular style center dump Corvette manifolds will replace many of the "ram's horn" manifolds fairly well. We'd actually convinced officials at a local track to accept them as late model replacements for the early manifolds by showing a copy of the parts manual listing them for a Vette. Watch for cracking in the "collector" where all four pipes are welded together. It's common. Some year manifolds have AIR tubes which can be cut off and welded over. I'm using a set of cheapie headers removed from a '74 K1500. They fit my truck quite well and with a few relatively minor modifications have sealed without hassle since '96 or so.

Making a TPI look nice isn't too difficult. Just take time and watch the details. This unit used a combination of off the shelf touch up sprays and some left over Hammerite gray for the nameplate on the TB. I had the additional job of removing dents from the very thinwall tubes left over when someone used a short Torx bit to remove the plenum to tube bolts. This is a pre-89 unit as evidenced by the cold start injector. You will want to retain this system if using the stock '85 ECM.

[Russell Ashley]

Those look nice. Would a setup like that bolt on to a 70's 350 engine?

[oossuuu754]

Will stock exhaust from 87 - 5.7 TPI Iroc work in the AD trucks? I bought the wiring harness and ECM from Larry Electric Site on the advice of some forum members here, still have to get the fuel pump and distributor.

[roger55]

Originally Posted by tmoble

Thanks for taking time. I did find your build thread link and started going over it. Lots of info there. Now a permanent book mark.

Thanks and you are welcome.
I hope to resurrect that thread soon. I've been working on an addition to our house and haven't been able to work on the truck for a few months now. Now it's looking like I won't be able to resume work on the truck until after the holidays. I still hope to complete the work on the truck by the end of spring.

[roger55]

Originally Posted by 58CameoAZ

Roger the exhaust manifolds on the 85 Vette are very similar to the ram horn type you have, and look like a small type of header, i think they will work out pretty well, that is my game plan anyway!
Allen

I was guessing just from looking at them that they will work fine. They are a relatively good looking manifold as well. Are you going to remove the heat shields or leave them on?

[tmoble]

Russell,

You need to check the angle of the center manifold bolts. on later style V-8s Chevy changed the angle of the two center manifold bolts so they stick up at a more vertical angle. Edelbrock or somebody like that wanted $85 for 4 of the wedge shaped washers. I made my own for free by cutting off wedge shaped chunks from a piece of bar stock. Later I discovered that Performance Products (of cheap chinese imitation intake manifolds fame) sells them for a few bucks. Not even worth the time to cut them off.

[58CameoAZ]

Originally Posted by roger55

I was guessing just from looking at them that they will work fine. They are a relatively good looking manifold as well. Are you going to remove the heat shields or leave them on?

I think they look better without the heat shield and took them off!
Don't know if their will be a sacrifice without them or not?
Allen