grafx

I drive a 91' Camaro 305 TBI and have recently purchased a TPI intake set-up. I've been told in the past that a TPI will work fine in place of my TBI as long as I replace chip, harness, and pump of course. Is this true?? I won't have any problems with installing a TPI on my stock TBI 305 motor??

By the way the TPI is off the same year car and a 305
-And have any of you performed this same thing on your own cars??

Tibo

iTrader: (15)

This is very popular and yes many people have done it or are doing it. You really need to use the "SEARCH" icon first as this is one of the most discussed topics on this board.

S10Wildside

I can rework your TBI harness to work with the TPI setup if you're unsure about how to do the conversion. Basically, all you'd have to do is plug it back in when I'm done with it. Contact me privately if you decide to do the conversion and want me to rework your harness.

grafx

Have complete Set-up----TPI intake, harness, and computer with chip, all out of a 91 camaro 305 TPI.

The car I want to install it in is my 91 Camaro 305 TBI

Besides the installation of the TPI intake, harness, chip, and fuel pump, everything else should be compatiable right?? I havent really looked at it yet but the fuel lines for my TBI run torwards the rear of engine were as the TPI run to the front so I will need to purchase new fuel lines correct?? Is there anything else that won't be compatible?

I've done a search on the subject of this swap and am having a hard time finding the answers to my questions so I figure I'll try and get them answered here. There seems to be a lot of interest in this swap but not a lot of good information. I think maybe I'll try and put together some sort of tech ariticle when I start this install, but for now I need your guys help...I want this to go as smooth as possible when I start this swap. I don't want my car down any longer than I can help it.

CrazyHawaiian

I'm not sure if the TPI intake will bolt up to the L03 heads. I have a TPI setup sitting right next to my old L03 but never even thought about it. I'm also in the process of converting an L03 (305TBI) to a LB9 (305TPI) but I did not consider using the L03 heads or cam because they really suck. My plan is to find a used set of LB9 heads and use either a L98 cam or a LT1 cam. In any event, I recommend you ditch those swirl port L03 heads. Whats the use of swapping to a batter intake, only to find that the old L03 heads and cam are holding you back?

CrazyHawaiian

Oh here's another thing about the TBI to TPI swap. If you have access to the donor car, make sure you get the TPI fuel hardlines from the rubber fuel hoses in the engine bay (right by the steering box) all the way to the TPI fual rail. They use different fuel hard lines, and this would have held me back if I had planned to swap in a TPI motor (I went from L03 to L98 based 350 Carb'd).

grafx

what about the computer chip?? Will the chip be compatable with my stock TBI engine??

CrazyHawaiian

I'm not sure. It will probably work, but I wouldnt consider it optimal. That chip for the 305 TPI was tuned specifically for the 305 TPI combo (heads, cam, etc). The L03 uses a different combo of parts. No harm in giving it a try. But if the motor performs really poorly, you might want to look into either replacing the rest of the L03 components with LB9 components (heads, cam, etc) or getting a custom chip burned (which I would honestly consider a waste of money for you situation)

Also make sure you get all the LB9 sensors from the donor car. I never went through with a TBI to TPI swap (so I didnt research it further, and I dont have personal experience doing it), but the TPI setup might use some different sensors that the TBI engine didnt have.

grafx

What is a good price for a set of used LB9 heads?? Someone has offered me a set of heads from a 91 G92 LB9 with 80k on them for 125 shipped. Does this sound like a good price?? Are these aluminum heads??

S10Wildside

One unexpected difference between the TBI and TPI systems is the way the A/C is wired. You will have to study the factory service manual for the slight differences. Since we're talking about sensors in the last few posts, the only one I think you need to replace is the temperature switch on the passenger side head and the knock sensor. From what I read in the service manual for the temp switch, the TBI and TPI sensor close at different temperatures. There are plenty of ways around using this sensor. Basically its function is for an overheating motor. When the temp gets high (I think it's somewhere over 230), the switch closes and forces the fan to turn on.

Regarding the electric fans, there are several ways to go at this, too. The TBI motor uses one electric fan. The TPI uses two fans...only one is controlled by the ECM. The other is related to the A/C system.

You need the correct ECM and correct memcal/prom for your specific application. You can not use a 305 program with a 350 motor. You can also not use a TBI program with a TPI program. If you need a prom burned for your application, I can erase and reprogram the prom in the stock memcal.

I don't know what to tell you about the heads. I was disappointed with the L98 heads on my motor and went with an aftermarket setup.

Ideally, you would be best off to find a harness from a 1991 TPI Camaro. However, your TBI harness can be converted to work. But you must have the factory wiring diagrams. If you understand how to read the diagrams well, expect to spend well over 20 hours studying diagrams and doing the conversion. I just did a TBI to TPI conversion on a 89 harness and that's about the amount of time I had involved in it.

Tibo

iTrader: (15)

I've done a search on the subject of this swap and am having a hard time finding the answers to my questions so I figure I'll try and get them answered here. There seems to be a lot of interest in this swap but not a lot of good information. I think maybe I'll try and put together some sort of tech ariticle when I start this install, but for now I need your guys help... [/B][/QUOTE]

If you did a search it was not very good. There IS a tech article on the swap. It covers the installation instructions, all of the parts needed along with part numbers and how to do a few odds and ends and trouble shooting. There IS a lot of usefull information.

Your LO3 91 heads will bolt up to the 91 TPI intake manifold. The bolt angle and pattern are the same. They changed the angle back in '87 So '87 up will bolt to '87 up. You have to get new fuel lines, you 15lbs stock lines will not cut. You should not reuse your stock LO3 chip. TPI is electrically VERY similar to an LO3. If you look at the harness on a TPI car, there are actually only Two injectors, and then three wires spliced of those two wires. The sensors are all the same(jodwise). Which brings up the point of having to swap out things like the knock sensor.

Ummm, the knock sensor does alot of things. Such as monitoring knock, and bumping or retarding the timing. The only way to get round that is a mechanical or vaccum advance distributor.

grafx

hey S10Wildside read my second post this will tell you what I have!!

Besides Heads, cam, and obviously intake, the blocks are the same right. I mean there's no difference between a 305 TPI block and a 305 TBI block is there?? Bore, pistons are the same correct?? So if I'm swapping everything from a 91' 305 TPI onto a 91' 305 TBI shouldn't all the sensors be the same except for those mounted on the intakes??

Dyno Don

iTrader: (7)

[So if I'm swapping everything from a 91' 305 TPI onto a 91' 305 TBI shouldn't all the sensors be the same except for those mounted on the intakes??]

No...the sensors are relative to the computer you're using.

You're wasting a lot of band width here and really getting yourself confused.

Just come by and I will explain it all to you.

S10Wildside

About those fuel lines. Having a set from a TPI car would be good, but you could also rig up some braided stainless or something of the like.

About the sensors, they are specific to the ECM you use...and the knock sensor is different for the 305 and 350. They look the same, but the are different.

CrazyHawaiian

Yeah now that I think about it, the L03 chip might not even fit in the 165 or 730 ECM. I didnt try to interchange the chips so I'm not even sure. I'd imagine the TBI ECM uses a different type of chip.

S10Wildside

Yes, it's totally different. You have to use a TPI memcal.

grafx

makes no difference I got a computer and the chip with the TPI

OneBadZ4U

Is it me or does "rig up" sound bad? You can buy the hard lines between the fuel rail and the rubber hoses from the dealership. I believe I paid $15 for the pair. Its tight behind the alternator bracket on the driverside. Braided lines may not fit right. Besides all the fittings for a braided line will cost a lot.

I switched my '92 RS From TBI to TPI. Works great. Takes a little time to make sure you get everything to work right(IE SES Light). Takes some time to work the bugs out. Its worth it.

S10Wildside

It's you.

That didn't imply good or poor quality. Your interpretation of "rig up" is based on your own experiences or your awareness of others. There's no reason why that can't imply a quality solution.

If the stock lines are still available from GM, I'd go that route.

grafx

Yes they are still available checked today!! Besides the fuel line from the throttle body to frame rail line, are there any other lines that need to be replaced. I head that the rubber lines from tank to fram rail line needs to be replaced because they won't hold up to the increase in pressure, is this true. I was told that TPI's use a hard line in this location.

Also I will need to replace the TV, throttle, and cruise control cable also right since they are different than the ones used for TBI correct??

One other thing, I found a set of good used LB9 heads off a 91' with 80k on them, does 125 shipped sound like a good deal??

OneBadZ4U

Glad to see everyone is not uber serious.
When I changed over to TPI, I used an '87 Sys. I had the hard lines from that system. I called the dealer and at that time they either didn't have or couldn't find the lines. Talk about "rig up", I took and bent those lines to fit. Ugly and dangerous, I had one running right behind the alternator charge terminal. Can anyone say FIRE! Safe to say I located the correct ones at the dealer. I can post the P/N if desired.

For your fuel line question. If your doing a "text book" swap, you need to replace the rubber fuel lines that are attached to the lines that come from the tank and attached to the hard fuel lines to the fuel rail. The lines are exactly like the ones you already have on the car for TBI except they are a higher pressure rating. Meaning, yes there are rubber lines for a tpi system too.

This falls into the do as I say don't do as I do. I just left my rubber fuel lines on from the TBI when I changed to TPI(Ok, I'm ready for all you all to "give it" to me for keepin' those stock lines). I haven't had any problems so far.

grafx

anyone know what this part # is for 14089403 ?? Some sort of fuel hose but not sure what hose. I have the other 4 for the 2 hard lines and 2 rubber from tank to frame line. But can't figure out what line or hose that number is for.

Also what about the cables??

S10Wildside

Hey man, only playing with you. I'm not taking it serious. That's what the was for.

About those cables. They are all different lengths. You need new cables.

OneBadZ4U

I know. That's why I said

You got no problems here!!!

:rockon:

grafx

What about the cost of the heads? Good or not??

JR92z28

Most of this is true, you can use most if not all of the sensors on your current setup. If I understand you right- going from 90-92 TBI to 90-92 TPI?

This is what the Tech articles are for...
All your questions should be answered here-
https://www.thirdgen.org/newdesign/tech/tbitotpi.shtml

Dyno Don

iTrader: (7)

Forget those heads. Its not worth buying stock heads. Your TBI heads will work fine until you are ready to swap in a 350. That's when you should spend the money on better heads.

grafx

that's what I wanted to do but everyone says they won't work. I asked this same question a while back and was told they would work now everyone is saying they will cause drivability problems.

That was my original plan to just install the TPI on stock 305 and wait till I had the money for a 350.