DenzSS

Good advice!

I've never seen modern cats cost an engine more than 7-8HP..and thats on some high hp blown applications. On most head/cam cars, its more like 5hp.

upnoveru2

I agree, that was great advice. I will have to get a dyno with the cats/catback off and see where I stand.

However, what are some people's thoughts on my original pull at 18:1 a/f for 375rwhp and then droping to 12:9 a/f and being at only 360rwhp? I know that lean is good, power wise, but I was under the impression that 18:1 was SO lean that it would have had the motor craving for fuel to make more power....? Any thoughts? I appreciate all your time folks!

10secondZ

iTrader: (24)

The wire near the starter you guy's forgot to plug in is the crankshaft position sensor most likely...try a crank re-learn with a tech 2 and try the dyno with no exhaust hooked up as mentioned before..should help a good bit...btw what did the plugs look like after the 18:1 run?? Good luck...the numbers arent horrible..but could deffinatly improve with other mod's.

Carter

upnoveru2

Thanks 10secondZ! So the crank has to be 're-learned' now? Is there any way without the tech 2 to acheive this? Is this something that could currently be robbing power? When that wire was unplugged the car was not charging and the alternator didn't work...we actually thought it was a bad alternator causing the problem. The 'tuned' runs were done after this problem was remedied (360rwhp), however we never did a crank re-learn.

The plugs were like new after teh 18:1, slightly tan...slightly. There were no speckles or anything. One plug (#7) was cracked on the outside porcelain and has since been replaced. It never seemed to misfire so I don't know if it caused anything or not.

I plan on a new dyno this weekend without catbacks...possibly without cats as well. I will surely post results...ESPECIALLY if i run into issues. The only other obvious mod that i know of that could be holding me back is a ported throttle body...do you agree?

Beast96Z

iTrader: (21)

I'm with you on the 375/18:1 thing. You made more power untuned. Something has to be up. Even if the tune gained you nothing but correct A/F ratio's, you should have still made 375 again. I'm thinking something is wrong mechanically or tuning wise.

Ron@Vengeance

iTrader: (51)

Did the lil wire by the started happen to be the crank position sensor? Your stock catback is NOT holding back 30rwhp. Do you have a midpipe? They are worth a good bit on C5s. Also, check out CorvetteForums.com.. I have some pics of some C5 throttle bodies I have been doing. They look badass and are making some good #s on the dyno.

BTW, wheres the dyno in Peoria?? I have been to the airport several times there on my way to La Harpe for the Fred Gibb show etc etc..... SMALL TOWN

gomer

iTrader: (13)

I'll be the first to say that Ron is a ********.. but he can port the hell out of a throttlebody... for a ******** I'm running one on my car and I'm VERY impressed with it. I think you'd gain a good bit from replacing the cats and midpipe on your car with a good offroad X pipe, that would be a very worthwhile mod.

angst911

EFILive can do the crank position sensor relearn also... don't know of any other way though.

ATXCAMAROGUY

iTrader: (4)

Sounds like your a good 30-35rwhp down compared to other H/C setups. Good luck

Greg Fell

iTrader: (9)

Would there be any driveability issues if the crank position needed relearned? If we autotap it, would we see a ton of missing timing?

Greg Fell

iTrader: (9)

Looking at an atap run, there is 6-9 degrees of knock retard at times....