I've looked around and can't find a direct answer to my issue. I have a 92 305 TPI and got a 87 IROC 350 TPI motor that came with extra with my car (my uncle is generous). My question is about the EMC PROM Chip exchange between the years since mine has the ESC built into the ECM (1227730 ECM) and the 87 TPI's had it externally. Can I just get a new chip programmed for the 350 and use it in the same ECM or do I have to have the old ECM and somehow splice the ESC into the harness? Also there is the question of the lack of Anti-Knock sensor on the 87, if I'm correct.

or point me in the direction of a post that answers this if available.

Thanks

 

Really it should be pretty straight forward...

For starters, I think the 92 cam is slightly better. If my data is correct, They both have a duration of 202 & 207, but the lift is slightly better for the 90-92 Cam (even the 305 Cam) So you would probably suffer slightly there. You should not have the Peanut cam in your car, as in 1990-1992 all TPI cars should have gotten the same cam 10111773.

Some changes from 1987 & 1992,
87 was MAF, 92 was MAP or SD,
87 had the 9th injector for starting, 92 did not
350 vs 305 had different knock sensors.

If I did the swap I would use what is in the car now, and use the 92 ECM, which I hear most people say is a better way to go. I remember more people saying that the MAP type of setup is better than the MAF. MAF is easier to make modifications to, but the MAP produced more power. You would need to find a chip for the ECM tho, or make one yourself.

Honestly I do not think you will see a huge uptick in performance, it will be a little, but not something that will blow your socks off

I would also consider going with Vortec Heads since you will have it all out of the car anyway.

 

The 350 torque will be very noticeable.

 

So your saying to keep the 92 305 that's in the car now? Would it be possible to swap the cams from the 92 into the 87 or put a different cam in? Also would the MAP and MAF really be that different to the motor if it's processed through the computer? Never had to mess with MAF and my 92 has MAP I believe. I was also told I could just leave the 9th cold start injector unhooked or plugged up or just use the 92 fuel rail stuff to make it work like the 305 w/out cold start injector. And lastly, what would I need to do to get the knock sensor to be compatible if I do the swap? I was told to swap it from the 305, but my main concern with sensors and ESC differences between the years with the computer.

As far as horsepower, I would agree it's really not much. 92 305 has 185HP and the 87 350 (going off the block numbers) was rated at 230HP. And thanks for the knowledge, I really don't know much about peanut cams, but it sounds bad lol.

 

Also forgot to ask, which motor were saying to put the Vortec heads on?

 

I would put the Votec heads on the 350...

If it was up to me and I felt ambitious this day I would:
1) rebuilt the 350, install the Vortec Heads, get the Vortec Lower intake, might consider going with a 1.75" runners.
2) The 9th injector can just float there, it does not even need to be hooked up if you are going to use that intake. I am using an 89 PROM in my 87 with the 9th injector disconnected without any issue, if you have the engine out, you can just plug the back of the Left frame rail.
3) I would probably get myself a nice cam, something that goes well with TPI and the Vortec Heads... I think Scroggin Dickey may have something, but I do not know.
4) I would use as much 1992 as I could, use the ECM, the wire harness, and everything, When you had both motors out you could check to see which sensors are different. Like I mentioned before, AFAIK, the only difference in sensors for the 350 and 305 was the knock sensor, and I am not sure how critical it is.
5) You have a screaming tall gear, at 70mph you must be turning around 2500 RPM, If you want 1/4 mile times, I hear that is not the best gear, if you just like the seat of your pants feeling of acceleration, then that is what it would be for.
6) Use the Accessories and the brackets IE ALT, A/C, from the 1992, the serpentine setup is way way better than the early V-belts.
7) Headers will do wonders too...

At this point you would need a custom tune... Some people can get it close for you by letting them know what you did to the engine, but a custom tune would give you the best results, especially with that tall 4.11 gear. If you have not already, I would also get the Corvette Servo and a good shift kit for the trans.

just trying to give you direction.

HOpe it helps

John

 

Thank you! That was exactly the info I was looking for. I already have Edelbrock short headers with a full borla 3" exhaust and the 4.11's which all came with the car when I bought it, but I don't drag just like to cruise and enjoy the sounds. But i do plan on doing the t56 conversion at some point, so would you think it'd still be worth it to get the shift kit? But yeah it screams at 70mph and the electronic gov kicks in around there too.

 

Get a 350 knock sensor. It's important. The tuned frequency will pick up knock incorrectly.

4.11s and TPI are "bad" because it pulls you out of your power band too quickly making you slower. It feels faster due to torque multiplication, but is slower. Of course this is a generalization that does change due to a multitude of variables.

If it were me I'd switch to SD using the 92 ecu and buy a 350 memcal. Then ship that out to be tuned. Or better, learn to tune yourself.

 

What tuning equipment should i use? And do you know a reliable source for custom memcals and how do I change to SD?

I wanna make sure I do it right.

 

IF you are planning to get a T56, then I would not worry too much... I know if you put too much power thru a standard 4L60/700R4 they will eventually stop working. There was more than one version, I would hope that with the TPI you would have some performance parts...

 

I do plan on doing a few upgrades over the years. Heads, lifters, fuel pump, cam etc. I just don't like auto and I heard that the t5's are junk.

 

The T-5 is not horrible, They just can't take the beating of much more than a stock engine. The T56 is much better tho. I have a T5 behind a 350, and it does not give me any problems.

 

Thats good to know from reputable people. Family background was in the salvage yard biz till 2008 and they said people would break them often. But thank you for all the advice and information. I'll make sure when I'm all ready with money to get it all done at the same time.

 

Although, after some research I found that some of the LB9 motors had the L98 cam instead of the peanut cam. This motor is from a 5sp car if that makes a difference.

 

According to the "replacement" parts, all LB9 & L98 engines got the same cam from 1990-1992... 1987-1989 is a different story, the LB9/A4 had the "peanut cam" for sure, some of the LB9/M5 got the L98 Cam, but not all... (had to do with gear ratio if you are really interested) and of course there was only one cam (for the US Market) for the L98. The 88-89 L98 cam was the hottest cam for any year.

 

Thanks. The car it came out of had a 3.45 9 Bolt rear. Do you know where I could find what gear ratio's had the L98 Cam?

 

Peanut cam vs L98 Cam

Peanut Cam
87-89 10088155 - LB9/A4 (all in US)

L98 Cam
87 14093643 - All L98, LB9/M5, & Exported LB9/A4
88-89 10066049 - L98 & LB9/M5
90-92 10111773 - L98 & LB9 (All)

I was mistaken, I for some reason thought that it was tied to the gear ratio, which it is not, I got that confused with the speedometer/tachometer combinations for some reason oh well.

 

I think I'm going to go with the 350 motor just because I have it then. I was the original motor in the car with the M5 that was paired with it. What cars can the Vortec Heads come off of? I know I'll need the custom intake but is there anything else I'll need or work Ill need to do to get them to fit?

 

96-98 Pickup trucks. had the Vortec Heads.

I do not know everything you will need, I have never done one, I looked into it years and years ago, but never did anything... Maybe some day.

John