Does anyone know whether or not the 5.0 TBI engine is rev limited via the ecm? Mine seems to run out of power at 4000rpm.
even with the limited cfm rating of the factory TBI, it seems that it should pull farther than that!I have added an open element 14 inch air cleaner, and bumped the timing up to 4 degrees btdc.
Still has the same problem.
Anyone have any input?

 

it is not rev limited. You will know when you hit a rev limiter.

 

Welcome to the boards and welcome to the inadequacy of the stock 305 TBI. It has a lame cam, heads, intake, and exhaust which all equal junk performance over 3500 rpm. There is no rev limiter per se, only the limitations the stock parts yeild.

 

valves tick at like 5500 rpms don't they? (in stock engine)

 

Only if there is something wrong. I used to shift at 5,200 or so RPM when my car was stock. I was aware that it had stop making power thousands of rpm's earlier, but I didn't really care. I missed a shift once and pegged the tach. She made it out alive after a full nascar RPM experience there.

 

Shifty, do you honestly think an L03, even stock, won't make power past 3500 rpm??? Come on now, that is taking it a little far don't you think? 4k maybe, but I don't buy that either. I know of one member here with a verified dyno who's peak hp was at 4700 rpm with only full exhaust and nothing else. I myself shaved off half a second of et by shifting at 5k rather than 4400 rpm. Granted that's still not very high compared to my LS1 that I shift at 6400 rpm, but it's not 3500 bad, lol.

 

Yea you are right I was a bit harsh. Your sarcasm detecter is working great today . Stock dyno graphs show that peak power is right around 4k or so and anything past that is a cliff like drop in the power curve after a slight platuea. A full exhaust like you said greatly inproves things past 3k as you described. Also, most tachs are off and are actually much lower than the gage reads by a few hundred rpm. I think Dewey shifts 1 or 2 mississippi's after the tach reads 5k. ha.

 

The car isnt rev limited, but it is speed limited (at least in mine) at 107 mph, then the fuel cuts off. A bitch if you changed rear-end gears without recalibrating your speedo.

 

To the best of my knowlege, the 88's didnt get the speed limiter set as they used a different ecm.

 

It isn't limited in stock code but if you want one it can be patched in. The patch basically changes the code to look at engine RPM instead of MPH. RPM = 8-bit value * 25 while MPH is just 8-bit value. So if your "mph limiter is stock" at say 107, then 107 * 25 = 2675rpm limiter. That's good for keeping your friends from romping around . I set mine to 6000rpm (6000/25= 240) and resume just below that.
That patch can be found on the DIY-Prom board.
https://www.thirdgen.org/techbb2/sho...hreadid=108380

 

I once accidently burried my tach. For a good couple of seconds. She ran a little shakey afterwards, but run the same as always. From what I understand, the speed limiter on the RS's is 112 (actual, now what the inaccurate gauge shows).

 

These LO3's are strong as all hell. I've also missed a shift before and buried my tach, still ran great. I've also buried my temp. guage as well. Ran like it was still warming up...

 

170 hp can't hurt anything except your ego :lala:

 

I'd be offended if that wasn't so rediculously true...

 

Dimented, where did you hear this, and how accurate is this information? I'm not challenging it, I'm just getting my hopes up....

 

Is it true that in 88 an lo3 equipted car is not speed limited? I have a '92 but I put a 88 ecm ( I'm not sure on the id) in there. It runs great but is it now limited? Just wondering.

 

all LO3 equiped f-bodies are limited to 118 according to gm.

later
tim

 

Speed limited by bcc;
https://www.thirdgen.org/techbb2/sho...hreadid=260438