piecesparts

I am working on a 90 Corvette L98 that has had the heads changed out for a set of Vortec heads and the upgraded base plate. The stock plenum and the base plate are mated to Edelbrock High flow runners and the the rocker arams have been changed over to 1.6 to 1 ratio roller rockers. I am going to install this in to replace a TBI 5.7 motor in my daily driver. This is in line with the setup that Scoggin Dickey sells for an upgrade on the limited HP level of the L98s.

I got this motor with the TPI already refurbished by S&P and the injectors upgraded to a better set. The computer has been set up to be installed in a streetrod and according to the guys at S&P it should work well with the factory installed computer for a good combination. Everything is set to hook up to the 700R4 tranny and bolt in to the truck. I have already gotten the different alternator and A/C brackets to mount on the motor for the room needed at the intake opening. I have removed the factory clutch fan and installed a set of electric fans for more room. I also have purchased the TPI fuel pump setup for increased demand.
Has anyone done something like this and what pains am I looking at? I realize that this is an old question, but the LS1 is waiting on the engine stand for my 68 Chevy street truck. So once I get this working, then on to bigger things.

RednGold86Z

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It's not hard. Sounds like you've covered most things - Did you get a TPI Wire harness?? That would make life easier, but you probably could re-pin and rewire the original harness as well (but it's a bit of work). Try to get a full engine to computer harness. I don't think you'll need the truck's computer anymore (but I may be overlooking something).

Hope you got all the sensors with your TPI.

Hope they disabled VATS, EGR, and AIR in the ECU (since they say it's for a streetrod, they woulda had to). Did you get a 727 ECU (vette), or a 730 (F-body)? You could use either, but try to get the harness that matches (but either could be slightly modified to work with either).

Hope you also were able to get the TPI fuel lines that go into the fuel rails.

Otherwise it's just getting power, key, ignition, and ground wires connected. Then fire it up (and check for leaks).

Prolly a bajillion little things I missed, but don't be afraid to just go at it. I did a 79 malibu in just a few cold (but mild, lucky, February, Iowa) days last winter (but then again, EFI is my career, but it's all available on the internet somewhere).

Shagwell

I've got a 350 TPI vortec headed motor in a 95 4x4 Tahoe. I'm currently putting my eaton blown 305 TPI in my 95 burban.

- Fuel lines - I re-bent the factory steel lines to bring them up to the front of the motor. Then slightly reworked the TPI steel lines to drop down around the power steering pump and used the factory TPI rubber lines to hook between the two. Same size and type of fitting. - You will need that pump you bought, but externally they're identical, so it's a simple swap.
- Computer/wiring - As stated above, do you have the TPI harness or are you gonna re-pi/re-work your factory harness? I laid both factory harnesses out on my patio along with the diagram for each. I then stripped each harness of what wasn't needed and made one out of what I did need. - The 95's have tha later dash then yours, but I'll assume you still have the under-hood fuse box? Many of the factory TPI under dash wires will have to be run under hood to the truck fuse box. I also used the truck injector on power, but used it to trip a relay to carry the injectors, instead of triggering 4 injectors(2 fuses, one for each bank) on a power wire made to carry 1(tbi). I used two of the factory un-used large fuse locations for a fuse for the injector relays and a fuse for the electric fans. You will need the TPI ignition control box, as the tbi box has different settings. You also need the TPI knock sensor, and MAF/MAP(depending on which ecu you're using). The temp sensors and the oil sensors can be either the truck units or the TPI units. Depending on how far away you mount the O2 sensor, the truck 3 wire may be needed to heat the element properly. - One thing I can't stess enough is that you use care to fully/properly make each and every connection. Lay it out, measure twice, cut once(factory TPI harness is about 34" too long) Loom it like factory.

Looks like you have the rest pretty well covered - It's not to bad of a job, the TPI powerband is absolutely perfect for a truck. The Tahoe is knocking down 20+mpg highway, 18 in town, with 3.73 gears and 33" tires, and it'll run with many performance cars.

Doctor J

You might check this guy's site for a thorough write-up:
http://www.tpisuburban.edgesz28.com/

piecesparts

YEP---I have the S&P wiring harness, that came with the TPI unit in the first place. The previous owner had plans to put the L98 motor in the 1968 Chevy truck that I purchased form him. He had already had the motor topend disassembled and the TPI refurbished. I came with the wiring harness, computer that had been reprogrammed, K&N air cleaner, T/stat housing, and cleaned fuel injectors. I went to S&P earlier this year and had the computer upgraded for the 25LB injectors that I put in and changed the fuel reails to exit on the drivers rear side. Along with that, I got the adapters and stainless steel flex lines to connect to my stock fuel lines. After that trip, I got the idea from an article in Chevy High Performance for the Vortec heads and the different TPI base plate with the bigger runners. The article said the power curve would expand significantly and would allow for a better top end horsepower. I believe that with the different injectors and the better flowing heads, this motor should be a great replacement for the factory TBI 5.7 in my Silverado.

The motor was a low mileage aluminum headed L98 that had been hanging on an engine stand for quites some time. I took it down and replaced the seals, and verified the bearings. Then I started assembly with the newer heads. I purchased the Camaro brackets and fitted them to the motor as well as a new 7 qt Moroso oil pan and an Edelbrock water pump.

S&P advertises an Intergrator kit for the replacement of TBI to TPI, but they did not have the cards to make the kit. They said that they do a lot of installs where they leave the original computer to run the tranny part and put in the updated computer for the motor's operation.

Shagwell

I've looked into doing the piggy-back computer set-up for another vehicle. You have to let both computers get info from the sensors. Obivously the engine ecu has to read all functions, but the trans ecu will have to read throttle position, MAP, coolant temp and I believe it has to read the distributor. - Makes for an under dash with a lot of clutter with that much wiring and 2 ecus. - I was doing a fresh trans when I did the motor, so I just plucked the 4l60e and dropped in a 700r. Makes for a clean/simple install.

piecesparts

I already have the 700R4 in the truck and the guys at Street and Performance said that this install would be simple, but the factroy installed computer would be needed to do the speedo and lockup inputs. Their computer would be needed to run the engine components. That is the point that I am working to solve.

RednGold86Z

iTrader: (1)

The TPI computer can also run the lockup if done correctly. Look into a Dakota speedo converter to do the speedometer in the dash. I've never done this, though. On the 79, just used a cop car speedo output on the 700r4, and it has both a cable drive for the mech speedo, and the magnetic VSS for the computer.

Shagwell

or just toggle switch the tc, or use a hyd lock-up kit, or run a 4th gear only lock up kit, or run a standard non-computer lock up kit......

As long as the speedo will read the sender at the trans, with proper programming there's no need for the engine ecu to read the speed if it's not controlling the tc.

RednGold86Z

iTrader: (1)

Unless you want to run Lean Cruise mode. Or have DFCO (can edit bin to allow, though).

At least, you should connect a park/neutral switch (should already be available from the TBI setup).

If you get it setup to control the converter with the ECU, and can edit the PROM, then you can make it work the way you want it to, and let a friend drive it without burning it up.

jmiller

Shagwell,
I put TPI in my 91' Chevy truck which should be the same as his 91'. My 91' trans operates the same as my 87' IROC, so he shouldn't have to worry about all that stuff. Mine works fine with the 88 TPI setup I installed in it. Hooked the trans up to the painless wire harness and it locks up and shifts fine. 91's still used the TV cable for shift points.

Shagwell

the TV cable doesn't control the shift points on any 700r. It controls part of the function, but not the shift. The governor controls the shift, the TV cable controls trans line pressure which changes the shifts via differences in pressure against the governor. Which is why there is only one proper TV cable setting.

- anyhow, I too agree that there's no reason the ecu can't be set-up to operate tc lock-up. The only thing I don't like about factory computer controlled lock-up is that it locks and unlocks too often. Constant lock and un-lock shortens the life of a 700. I do know of some people who have re-programmed the operation and have it working quite well though.

jmiller

Shagwell,
All I meant when I said TV cable is that the ECM is not controlling the shift points, of coarse the governor controls WOT shift points. I've never owned a newer vehicle with ECM shift control, but I would imagine they don't use a TV cable.

Your right my truck does unlock/lock. What I noticed after putting in the TPI is at cruising on the freeway at 65 mph I'm not in the throttle enough to lock it up where before with TBI at 65 mph it would unlock because I would have to get in the throttle to keep up to speed. I can't afford a chip for it right now, but that would solve the problem.
TCI makes a electronic module that installs in the tranny and then you just hook up a brake switch to unlock it when you apply the brake.

My 2 camaros don't have this problem because they both have TPIS stage 4 chips.