LOL, I didn't disconect my battery when I insatlled my Hooker LTs. <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> I unbolted the starter, but didn't remove it.

 

See, I hate to disconnect the battery because it takes my PCM forever to hold enough of an idle to do the relearn procedure. And my cam isn’t even that big <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

Thanks for all the input guys, I'll try to reply:

ArcticFormula
TECH Enthusiast
Member # 1909

posted June 26, 2002 10:02 PM
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SS125 your car had 111 mph trap speeds with a basically stock exhaust and lid. That is awesome. I had a Turbo Trans AM I sold to get my 02 Formula and all I can say is that seat of the pants the Formula with its A4 would trap around 100 in this summer weather. You are set for letting a little more air into that thing with the adjustible maft, I think the injectors should be up to it, but I am new to these cars. If you picked up another 20 rear wheel horsepower on top of the previous 333 you dynoed (like the mustang) you would be making 353 rwhp, which like you mentioned is Z06 territory. I don't believe the newer f-bods with exhaust modifications are a Z06 car, but I guess there are factory freaks.
Regards,
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Posts: 84 | From: Chicago | Registered: Dec 2001 | IP: Logged

I'm not saying it's a freak, but unless the dyno was f'd up last time (and I don't think it was because me and the Cobra dyno'd only minutes apart) I expected more that 1.8. Heck, I guess I would be somewhat happy with 10 at least something, just to see a difference.

Trevor D

Phat Dubs Director
Member # 15

posted June 26, 2002 10:15 PM
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You need to lean the car out! A 12.2:1 a/f ratio is pretty rich, and you'll find your power in a leaner a/f ratio. I'd target 12.7-12.8:1 if it was me. That would still be safe and help you find your power.

I'm going to lean it out, I'm also going to take off those Thunder Racing MAF ends also.

felton316

TECH Fanatic
Member # 1426

posted June 26, 2002 10:48 PM
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Did you use the same dyno? and were both numbers SAE corrected? Did you disconnect your battery so the PCM can re-learn? After I got done installing SLP LT, my dyno increased 25 hp and 23 trq. That was with out even playing with the MAFT. Now that it is tuned, I hope it would increase a little more.

PS. I have not been able to run it at the track yet, so I don't know any et/mph increases.

Yes, same dyno, same operator, same location and yes, same standard of correction. No, I didn't disconnect the battery (but don't forget, SLP installed those headers and the cat back. Would they have done that?)

TECH Enthusiast
Member # 5005

posted June 26, 2002 11:04 PM
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Probably your converters are the bottleneck. Stock GM converters are somewhat restrictive (from what ive learned).
I used to have a DOHC Cobra and I know the converters on those are pretty free-flow. That could explain the big gain for the Cobra.
Im sure also your A/F ratio is messed up also. Your 02 sensors are not that accurate unless on WOT.

I have the Random Tech cats that came with the SLP LT's. They are supposed to be pretty free flowing so I understand.

HOSS99
TECH Enthusiast
Member # 1728

posted June 27, 2002 08:21 AM
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Those are peak numbers. Was there any noticible increase throughout the graph curve. Maybe you making more power at lower RPM's, and about the same at peak.

Where did you have it Dyno'd, and what kind of Dyno for this run and the previous runs, and what was the outside Temp for both runs.

[ June 27, 2002, 08:23 AM: Message edited by: HOSS99 ]
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Posts: 37 | From: Macomb, MI | Registered: Dec 2001 | IP: Logged

The dyno graph might as well be one line, there is very little difference in the curve. It looks like an overlay on the 09/14/01 dyno. It was dyno'd at Advance Chassis Dyno in Sterling Heights. This was the same dyno used 09/14/01. Same operator, same setup, same standard of correction. Temp was up about 20 degrees. And yes that could make a difference, but, the Cobra increased 22 in the same conditions, the Z06 hit right where others say theirs have dyno'd.

 

What kind of timing did your motor see before and after exhaust work?

 

Well, I took SLP's advise and went to the track today. If the dyno numbers don't mean anything (according to SLP) then the et's and how I fair against my buddys Cobra would be the telling tale. Let's see, according to SLP, I would see up to 1/2 sec decrease in et and increase in mph by up to 5 mph. Well, here is the results:

Previous best et - 13.058
Todays et - 13.042
Previous MPH - 111.61 mph
Todays MPH - 110.13 mph

Theres the results. As far as I can see, the headers and catback did nothing. What does anybody suggest I do now. I can't get "Horsepower" to respond to a post on the problem here. Any suggestions?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SS125:
<strong>Well, I took SLP's advise and went to the track today. If the dyno numbers don't mean anything (according to SLP) then the et's and how I fair against my buddys Cobra would be the telling tale. Let's see, according to SLP, I would see up to 1/2 sec decrease in et and increase in mph by up to 5 mph. Well, here is the results:

Previous best et - 13.058
Todays et - 13.042
Previous MPH - 111.61 mph
Todays MPH - 110.13 mph

Theres the results. As far as I can see, the headers and catback did nothing. What does anybody suggest I do now. I can't get "Horsepower" to respond to a post on the problem here. Any suggestions?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes, you are TOO RICH, as Trever D stated. 12.2 is simply too rich. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Lean the mizture out and it'll pick up, trust us....

 

Problem number 2 is the cats. All of these guys that you see on here posting their 20+ hp gains from headers are running off road pipes. Check out ls1speed.com and pick up a set of their custom off road pipes for the SLP headers.

 

I so happen to agree with SLP's assessment of .5 second and 5 mph. I picked up at least that when I put mine on last year. Again I run with ORP and tune it lean and all 'h'.

What was the weather on your other run, what was the weather this time? You can't compare apples and organges.

Go back to the track. Tap it lean.

And get a converter <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

David

 

Number 1, you are way too rich. That would be good for 10lbs of boost but really sucks for N/A. Try 12.8-1 to 13.0. I have never seen any use for a maft on a stock head/cam motor. I've never used one and only 1 has gone quicker Internally stock than I have.Use a stock meter or gmaf(gmafs give a few more degrees timing and keep the A/F where it needs to be IMO). Number 2, the cats are terrible.Trust me. You will probably see a 15-20 hp increase going to offroads.By the dyno #'s you said you did before, it seems you might have had a better weather day also. Its damn hot/humid out now and you can see as much as 5 rwhp for every 15 degrees from 90-45 degrees.I lost 4 tenths when I went to slp's and off-roads with a 4 inch mufflex.

 

first off..

a dual overhead cam'd cobra v-8 is in no way a comparison to an ls1.. if the cobra lay'd down 300 thats great but if you look at your dyno graphs then i will guarantee you that you are making more torque at a much lower rpm that the dohc motor...as i have seen it in the past those dohc motors are pretty doggish below 3500 and then wake up real fast around 4500..

just my .02

secondly, wheather has just about everything to do with your car's et...

in vegas we are seeing 110 degrees in summer temps and 45 degrees in winter temps.. in the winter my car goes 12.50's all day long and in the summer 12.90's if i am lucky..

winter mph 110
summer mph 108

third.. as far as i have seen... 5 sets of slp's LT's with 3" y no cats have only averaged a peak gain of 10rwhp.. however the dyno graphs between before and after are completely different...the torque picks up a lot lower in the rpm band with the longtubes compared to the stock manifolded style.. peak hp is not everything!!..

how many miles have you put on your car with the headers on...
example..1
put slp lt's on buddy's car and
he drove 3 miles and then we went at it my car vs his and i pulled him bad... and he had always pulled me before... turns out the pcm had to relearn a lot and after 50-75 miles of aggressive driving his car was back to normal..

lean out the car a little more and wait for a little cooler temps....

<small>[ July 02, 2002, 08:47 PM: Message edited by: Grease Monkey ]</small>

 

Id get the A/F ratio to 13.0:1

SLP headers are the worst for performance IMO..

 

Just my personal opinion, but I'd dump those maf ends and reset your ECM.

 

There is lightly modded M6's that dyno this...

"333 rwhp seems very nice as well as almost a 112 trap speed when all you have done on allowing more air into the motor is a lid. Am I missing something here? I hope my car will respond that nicely to a lid (free flowing airbox or whatever), as I already have a GMMG, and think the headers are really for higher horsepower applications anyways. I would be happy with your results. I might have chosen a higher lift cam before the headers, but alas I don't have any money to put into my car anyway. Good luck with the ride.
Regards,"

Den.

 

I have an m6 and cam now but I would be pissed to only get that kind of numbers..it isn't a mustang dyno is it?? I have seen lots of header cars that dyno around 350hp I think and around 380 or so with cam and headers and the other mods less heads.I have only got 108.4mph with my cam and no headers and my other bolt ons right now but its hot and humid out and think I should see at least 110 without headers.I plan on ordering some tts this week..I better see some gains...and not just under the curve..peak hp gains..I also think that 12.2 is still way rich..did you try to take it to
12.8 /13??? maybe go back and retune for that ratio like has been suggested..not sure what else would make your car not respond to the headers.
I have no dyno here so can't give you numbers for my car.I just know that my last two mods ,my b1 and ls6 intake made a very noticeable sotp difference in my car.My times don't really reflect much though..got a 13.63 at 108.4 altitude corrected for 1900 feet..not density altitude corrected for the temp,humidity and bar.
I thought my mph was a bit low but didn't powershift..shifted at 6100 or so on my shiftlight,got a 2.31 60ft on that run and only made the one run.My car is heavy ,race weight that day with me in it was 3880.full tank of gas..heavy subframes,sound insulation,sub box,etc.
I am really hoping to see an 111 at least with headers and 113 to 114 corrected for altitude on cooler days..especially with cam and headers and ls6 and other bolt ons.I would give those pushrods a check if I was you and check for any possible other problems..vacuum leaks ,etc..
bent pushrods can take away power I hear.
Your car does have a higher trap speed than most of my buddies ls1 with basic bolt ons ,no headers or cam around here..they are only getting about a 107.5 or so corrected in current temps and weather.Your before header trap speed was high I think..

 

Did you notice any knock retard on autotap?

-Jim

 

I'm no tech expert but a friend of mine put a GM hot cam and headers in his an he swears the cam didn't help it. After Atap, they found the knock sensor was retarding the timing. His car did run louder and it was at higher RPMs the knock sensor kicked in.
Maybe the headers are making more noise and triggereing the sensors? My 2¢