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temjin9876
02-04-2003, 03:16 PM
I am getting my hands on an anderson powerpipe, 80mm shorty Pro-M, BBK H-pipe w/cats, and a flowmaster Force II catback soon.

With these kinds of mods, what can I expect to gain from an average dyno-tune afterwards?

Also, how will these kinds of mods affect my A/F? I had someone tell me that the exhaust will lean me out and the pro-m will richen(?) me out. Or was that backwards.....:stupid:

tcrews
02-05-2003, 07:49 PM
Probably not much at all, thought at least get it dynoed with A/F so you do know where you are.

The MAF will tend to lean you a bit (that's part of the reason they make more HP than the stock unit) and the exhaust is just opening up the exit path...but with cats not as much as the offroad pipes do.

That's still very minimal mods to pay $400-$500 for a dyno tune chip and gain maybe 2-7 rwhp. The mods themselves should bump you up a noticable amount on their own.

temjin9876
02-05-2003, 08:34 PM
what about the ignition timing.....should I just get the steeda adjuster and call it a day?

thanx:thumbsup:

tcrews
02-06-2003, 07:12 AM
Well it depends on what your current A/F ratio is...if you are running dead on you sure don't want to advance your timing. I'd drive the new mods for a while, then get dynoed with A/F metering and then decide what you want to do next.

Mystic_Cobra
04-13-2003, 08:20 PM
Tom, You're one of the guys I was hoping would chime in on my car. I am hoping to get 300/300. The only mods that I don't have yet are a blower, headers, and a chip, I think. My timing is set at 14 deg.

tcrews
04-13-2003, 08:47 PM
What are you currently using to adjust your timing? I didn't see anything in your sig file.

To hit 300rwhp takes a 'lucky' engine and about all the bolt-ons on the '96-'98 engines...

What I'd suggest would be some longtube headers, matching offroad X or H pipe and then a dyno-tune. Your current A/F ratio is right there so I don't see much to be done there (leaning out or adding timing) though changine out the headers could affect it enough to need some adjustments.....so a chip could help.

I've seen a few hit the 300/300 mark but a lot more seem to hang in the upper 290's (not that much of a difference really). With enough changes (MAF, pulleys, full-exhaust) a chip can help make everything work better together.

What are your SAE numbers? I don't like STD corrected because it's using the wrong correction factor and tends to inflate numbers (take mine for example...569 rwhp SAE, 597 rwhp STD and 594 actual).

Mystic_Cobra
04-13-2003, 09:28 PM
I recently added the Steeda Timing Adjuster and have it set to 14 deg. [just adjusted the sig]. I have a mac hi flow h-pipe and flowmaster 2-ch welded-in.
I think I have the other mods you mentioned (except for headers and chip).
As for the SAE vs STD, I only know what was on the dyno sheet and I think it's STD. I know it's a dynojet. I guess the correction is done in the software?
The only other thing that could be relevant is that I failed emissions test recently [VA]. I replaced the EVAP purge flow valve and O2 monitor as suggested by the codes and the light came back with more error codes. p1443-evap emissions control system control valve (again) and two new ones, p0420 and p0430-the pcm has determined that the catalyst system efficiency for banks [1 and 2] are below the threshold for the current engine operating conditions.
Need help on this, too. The only test I've done so far is with a laser pyrometer(?) to measure temps. My inspector says the cat is doing its job if the temp behind the cat is 100 deg or more hotter than the temp in front of the cat. Both were 110-150 deg hotter after cat.

tcrews
04-13-2003, 10:20 PM
Originally posted by Mystic_Cobra

As for the SAE vs STD, I only know what was on the dyno sheet and I think it's STD. I know it's a dynojet. I guess the correction is done in the software?
Yep, it's the correction factor applied to your 'actual' numbers. The dyno shop should still have your runs saved so they can pull them up and run them through the SAE correction (it's a menu option). Or, you can get the dyno run file yourself from them, download the 'runviewer' from dynojet.com and do it yourself.
p0420 and p0430-the pcm has determined that the catalyst system efficiency for banks [1 and 2] are below the threshold for the current engine operating conditions.
Sounds like the "hi-flow" cats flow a little too well, just buy some mil-eliminators. None of the codes you listed will affect performance in anyway. All they do is trigger the CEL to come on.

Did you make any adjustments to timing during your dyno session? Sometimes less = more. You could be running too much timing or could run a little more. I've seen more Cobras run 12-13 degrees and GT's running the 14+ degrees typically.

Since you've invested in an H pipe already you could just add shorty headers. Longtubes tend to make more low-end and midrange power but you'll need a new H-pipe as well. Shorty's and Longtubes peak about the same though so if you're just looking for a number either will do. Longtubes give you more 'average' power across the band though.

Mystic_Cobra
04-13-2003, 10:56 PM
Tom,
I'll see if I can get the file from the dyno or get the SAE corrected numbers (are they always lower?). I didn't adjust the timing any during the dyno session, but will next time. Any idea why the numbers change as much as they did for my three pulls? Is this normal?

I actually have a set of MIL eliminators and OR pipe in the garage. I will try putting the MIL Eliminators back in and see if they take care of the light. I was running with the mac pipe, but my inspector suggested i take them out when I flunked emisisons.
HC limit 76 reading 147
CO% limit .42 reading .52
NO limit 605 reading 1272
I passed with very good numbers two years ago with a stock H-pipe.

tcrews
04-14-2003, 08:20 AM
Your numbers varied because your engine was getting more into it's proper operating temperature. These engines do not like to be run cold (or too hot), they prefer to be run a little hotter than the old 5.0s. The changes are normal...if you continued making more pulls you would see the numbers dip as the engine got hotter :)

Typically SAE is always lower than STD. The reason is the correction factor applied. STD uses a lower temperature and I believe a lower barometer pressure which tends to elevate your numbers. When I dyno'ed it was a pretty cool day and I actually made 594 rwhp. Applying STD correction factors raised that to 597 rwhp. So even being cool that day, STD corrected to a cooler, less humid atmosphere. SAE (which is our standard) lowered my number to 569 rwhp as the temperature correction was higher than the temperature that day.

With emissions testing, it may be a good idea just to keep your stock H-pipe around....swap it in a few days before testing, get checked out, then swap back to your other pipe.

Mystic_Cobra
04-14-2003, 02:54 PM
I'm holding on to that stocker for just that reason. I'll post when I hear back about the dyno files.