Hey guys last post was about a month ago and it was suggested that I have the vacuum pressure checked and it is ok. I got so fed up with the car that it is currently at More Perormance awaiting diagnosis about the problem.

The car has the following modifications:
LT4 Conversion (LT4 Heads, LT4 HOTCAM, LT4 intake manifold, 1.6 rockers, and horrible computer programming)
52 mm throttle body
SLP 1 3/4" shorty headers
3" corsa catback
Random tech high flow cats
28#/hr injectors
Vigilante 2800 rpm stall converter
Transgo shift kit
K&N air filter

With all of these modifications the car managed a best of 237 RWHP on the dyno and with three subsequent pulls and 3 different chips the hp didn't improve. Everything is mechanically sound and has been assembled by a competent mechanic who builds stroker vettes/f bodys. Fuel pressure, individual injectors, cam position, part #s, o2 sensors, everything has been checked and we can't find anything wrong.
The car is currently at More Performance and I'm thinking about the 355 rebuild they offer because the engine has 92k on it but after reading several posts on this site I wonder if there is something honestly wrong with the LT4 conversion. I would appreciate any honest dyno reports for cars with the conversion or similar combo. Please help and respond with any and all ideas, as a poor college student I don't want to drop another $3000 + into something that will never live up to my expectations.

Thanks for your time
Mike

 

You got any runs logged with datamaster or similiar?

Jeff D.

 

I haven't used any computer diagnostic tools because they are all incompatible with the 93 computer. Thanks for the response and how do you like your 3.42 gears I have 2.73 and am thinking of upgrading.

 

Your question may be related to my concern over upgrading my stock rockers on my 93 to self aligning roller rockers like on the LT4. With 94+ cars you need to upgrade to a LT4 knock module to prevent the car from sensing the increased noise from the SA rockers as knock and forcing a timing retard. On 93's we don't have a knock module like the 94+'s (replaceable/upgradeable) but I believe that we still have one and it needs to be "desensitized" to prevent this inapropriate timing retard. I just posted a question requesting clarification on this issue so I don't runinto any problems when I upgrade.
Since the retard will be triggered by a false knock this would drastically decrease the your power output across your RPM range because the "knock" is always there.
Or so I assume, guess we'll both find out, hope this helps.

 

With the convertor, cam, and headers you got is your lowend lacking much sense your torque has moved up the rpm range? The 3.42's was my second mod after the Borla. I love them. Not to revy on the highway and I can get a second gear every time now without a shiftkit.

Jeff D.

 

I found a link regarding desensitizing knock modules on 93's maybe this will help.

http://www.charm.net/~mchaney/knock.gif

 

Mike,

Where do you live? Have you ran the car at the track?
237rwhp thats pretty bad. you're missing around 100rwhp.
How does the car feel? Did you have it dyno'd on the same dyno before the LT4 conversion?
My car did lose 10rwhp after I installed the 2800Vig but my car with stock heads and the hot cam dyno 328rwhp.
I good tune is worth a lot. I gained 30rwhp from a cutout, off road pipe and a tune. Even before all that I was at 297rwhp.

Lets us know what you find out good luck

 

Are you blowing any smoke? Have you checked you plugs to make sure they dont show something that isnt seen? Is it possible to get the disk on the opti off?

Just a few thoughts.

 

There is something about these 93's F-bodys. I just fixed my opti and replace my opti harness. Throttle response is back, and it is not looking like it is burning my coating off my headers anymore. But it still fouls my plugs in less than 2 minutes. TOO MUCH FUEL.

 

you really need to get it on a Dyno with a WB O2 sensor to see what its doing. It would be best if there was some way to get a scanner on there, because there is definitely something very wrong.