I finally had some American Racing longtube headers installed today (along with some Steeda underdrive pulleys). This makes my current mod list the following:

American Racing Longtube Headers + Catted H-Pipe
Borla Stingers
C&L Cold Air Intake
93 Octane Mail Order Tune
Steeda Underdrive Pulleys
FRPP 3.73 Gears

I’ll give the good news first. The car sounds pretty incredible now. Definitely more bad *** with the headers. There are all sorts of sounds coming from the engine and exhaust that I’ve never heard before. It is deeper, I hear more of a growl, and the car all around sounds more ****ed off. I am getting some trumpeting (that farty/raspy sound you momentarily heard at times), which I wasn’t expecting with the cats, but maybe this could be prevented with something other than a straight through muffler. Other than that, I am very impressed with the sound.

The bad news would be my dyno results (attached). Only 265 peak HP. My car is automatic, but I was expecting more along the lines of 290. Any thoughts on why my HP was so low? The lowest stock HP for automatic I have heard is about 240 (although I have heard people getting in the 250s). If you assume I was low at 240, that would mean the CAI and tune gave me 25, but I got NOTHING from the headers or UDPs.

As if the peak HP wasn’t bad enough, I am running lean at 13.6. When they took the car for a test drive before the longtube install, he thought he heard some pinging at WOT, which I hadn’t noticed, so I was lean even before the headers.

Could something be wrong here? Weather was hot (92 degrees) and humid today, but these numbers are SAE corrected, so the weather shouldn’t matter. Any other explanations on why I am so low?

Also, since I am already so lean, is there any more power to be had from a new tune?

 

The canned tune is usually conservative. My guess, even with the temperature, is that a professonal dyno tune would put you well over 300 with the mods you have. Before my cams went in I had 300 with cold air kit, shorty headers and xpipe, and my tuner spent several hours getting the performance and a/f ratio down. Given my car is a street car first and a drag racer second, even my tune was a bit conservative--he could have given me more if I wanted less streetability and more go for the track.

Think about putting a few bucks into a dyno tune after running around with the car for a while...

John

 

Jezz this is the second car that Ive heard of who recieved less then optimal numbers by switching to ARH Headers...I know its most likely just coincedence and the problem is in the tune but I find it kind of ironic none the less

 

I have always been a pessimist, so I don't totally discount the people that say this may be perfectly normal, but all of my research including internet/magazines/talking to tuners themselves, has led me to believe that my mods (CAI/tune/headers/UDPs) are good for at least 40 rwhp Even with a terrible baseline of 240 rwhp for an auto, that would leave me with about 280 rwhp. If this is "ricer math" then let me know, but 40 HP from these mods seems reasonable.

I am not totally sure about the dyno shop I went to. Part of the reason I didn't have them do a full dyno tune is that I wasn't sure how experienced they were. They really seem like they know what they are doing with installs/etc, but they only recently got a Dynojet, so I don't know what to think.

How can you mess up a dyno run to get inaccurate results? I have heard of it happening.

 

I have a couple of questions for you. Who's mail order tune are you running. And do you know what brand of dyno you were on? Scott

 

Hmmm, whom might be the first car you've heard of???

JGT, I have had a similar experience w/ similar mods. About the only thing I have that I didn't see on yours are the CMCV delete plates. The temp KILLED you, and I'm sure the lower gears didn't help.....on the dyno. I have a "Journal" on here somewhere talking all about my experience and dyno runs. I was hoping for near 325 rwhp w/ all of my mods. Bottom line, I rolled off 300rwhp w/ a 11.5:1 AFR. I've since added a little spark and leaned it out a bit (via a revised tune from TillmanSpeed), and would expect around 310rwhp. I think I heard of another local dyno day coming up so I'll get a chance to check things out, however Texas summers aren't the best for making good dyno #s.

Hang in there. The sound makes it almost worth while alone!!
And now that they are on there, it makes the choice of which power adder to get that much easier....i.e so much for turbos (I ain't taking the LTs off now!!)

 

WOW Something is wrong with that in a big way. I finally had my stuff put on. I had the JLTII on for a few months now and the headers with catted H put on yesterday. We did some datalog pulls with it and found it to be a bit rich with CR's tunes. I would expect that from a email tune. We bumped the timing up a hair and leaned it out a bit. We did 3 pulls. The first was 312 RWHP. The second pull is when we tweaked CR's tune with the handheld options it pulled 315HP and 328TQ. The last pull was a hot pull and it made 308. I for one am happy with it.

 

Oh yeah I forgot. That was on 87 Octane and here is the sheet.

 

What gear did they do the pull in? I'm not seeing the infamous torque convertor loop in that graph, which COULD mean they did a third gear pull, which explains everything.

 

I was wondering that too..... too many variables left open to make a decision on this one yet.

 

That is exactly what my first thought was. Third gear pulls are a waste of time and money.

 

I have been hearing that LT headers w/X-pipe are only netting about 15-20hp gains not very good for the price, I think it is only worth it if you are FI not N/A. JMO
My Automatic GT Dynoed at 270 with K&N AirCharger CAI only @ 45Deg low humidity,
S0 I guess I was full stock hp at 260 since the K&N only claims 10 - 12 hp

I have not Dynoed since my current mod list.
JLT II CAI
SCT XCal Tune 93
FRPP CMDP
FRPP 4.10
Roush UDP
MAC Axle Back

http://home.comcast.net/%7E2k05gt/images/dynorunc.jpg

 

yeah dyno pulls in 3rd are such a F@#king waste of time.. I learned that the hard way.

 

I had my car Dyno tuned on Saturday, before the new tune it dynoed at 455 rwhp after ARH LT's and stage 4 cams it dynoed at 468 rwhp @ 9 lbs of boost,I can't remember what the torque was,I know it was over 400, which Doug had already done around 8-10 pulls useing my Diablo, but the air/fuel kept going lean around 4500 rpm,so he had to start over with the SCT II ,which is better. air/fuel 11.5 across the rmps range. he said he thinks it had another 20 rwhp ,but the engine was hot at that point. I thought I would have seen better numbers with what has been added, but who knows.still I really like the sound of the cams and headers! just mighyt be a little to loud. sounds like a beast!!!!

Didn't mean to take over your post!

 

It sure sounds like you were on a Mustang Dyno. They are notoriously low when it comes to readouts. Try doing it on a Dynojet.

 

That's a great idea... for people who only view dyno numbers as some sort of bragging right. But it's a waste of time and money for people who view a dyno as a tuning tool (as it should be).

Comparing dyno numbers is a meaningless exercise, because of all the variables and since peak rwhp has very little correlation to how quick a car can run. Trust me... there are tons of guys out there with much bigger rwhp numbers than me, but they'd have a helluva hard time keeping up.

 

Well said Don!..........and so very true!!.......

 

Hey Don, no need to flame me. I was just pointing it out to the member who asked a question.

 

Sorry, nothing personal... I'm just on one of my periodic anti-dyno-number crusades again today. Every so often, something sets me off and I need to vent. It's all good.

 

This dyno was a Dynojet, and I honestly don't know what gear it was run in, but I will find out.

This was a Brenspeed 93 octane tune. I emailed him about the dyno results and he sent me a new tune. He said it should take care of the lean condition, but said it might not help my peak HP.

I haven't had a chance to test out the new tune on the dyno, although I can honestly say I don't feel much of a difference.

Anyways, I think I am going the custom dyno tune route. Even if I am an unluckly bastard with a weak GT, I want to at least make sure the tune is safe. It worried me a little to learn that I was running that lean, and the installer thought he heard some pinging at WOT.

When I asked Brent if the new tune would fix the pinging, he said to let him know if I hear any. But it might be tough to hear any over the sound of the longtubes and Stingers.

For those in the Chicagoland area, I think I am going to go to Sutton High Performance for the dyno tune. They seem to be one of the big names in the area when it comes to Mustangs.

So....How much more power you guys think I can get with a dyno tune?