The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Long tube headers

This article implies that bolting on longtube heasders with aftermarket cats and doing nothing else, there's 35 hp to be gained. Appartently, no tune is needed and they are using the stock air box. The factory headers look like they should flow well. I wonder if the issue is really the cats? Unfortunately, the side exhaust is lost. A 35 hp gain is impressive, isn't it? I also found it interesting that the install of the Steeda CAI gave them only an extra 10 hp. Here's the link:

http://www.stangtv.com/tech-stories/engine/let-it-breathe-2012-boss-302-intake-and-exhaust-install/?utm_source=rss&utm_medium=rss&utm_campaign=let-it-breathe-2012-boss-302-intake-and-exhaust-install
 
From what I can tell reading the article, they still needed a tune. I'm not sure how else they'd avoid the CEL from the rear O2s. Cooltech and Kooks have been trying for some time to elminate it but to my knowledge it's not possible without a tune that shuts off the rear O2s.

The gains aren't really apples to apples either. The first dyno they did on the project car was on a Mustang Dyno which are known to show lower numbers than Dynojets. Then the Dynojet comparison they gave was from a different car! The car they compared to had baseline numbers of 375 rwhp and 337 rwtq on the Dynojet. For comparison, my car dynoed 398 rwhp and 356 rwtq SAE corrected on a Dynojet in completely stock form (except Corsa axle backs). My numbers are consistent with several other stock Bosses. It's likely the true gain was closer to 15 rwhp and 10 rwtq, but without them doing a before and after on the same car, same dyno, it's just guessing.

It's not surprising the tune didn't produce much gain. That's been showing up consistently from other tuners. It really looks like Ford wrung virtually all the power out of the Boss tune that they could, while still keeping it alive on a road course over an extended period of time. I think that's at the root of all the CELs we see, but I'd rather have that than an overly conservative tune.

I'm not knocking what they've done and do applaud them. I'd love to find a "silver bullet" to get the Boss up to 500 crank hp with good durability. While they didn't put a price on the project, I would guess they spent 3k+ for the headers, full exhaust, intake and tune, and to have it installed by a shop you could add another $1000-$1500. So the question is more about weighing this cost, dealing with the predictable issues you'll have to work through, and increasing the risk of your motor letting go on the track and not being covered by Ford, all for 15-40 rwhp and a nominal gain in rwtq.
 
The powerband with just the headers and cats is nice and fat. Impressive.

Stock-with-headers1.jpg
 
If you ignore the angle of the lines and just look at the scale, the curves are pretty similar........ (i.e. both show rwtq over 350 at 5k rpm, around 340 at 6k rpm, about 300 at 7k rpm and about 275 at 7500 rpm....the same holds true for rwhp)



Uploaded with ImageShack.us

If I do end up going with an offroad X, I'll have to consider bigger mufflers and I'm not sure what that does to the power band. That or just make it a track car. My buddy with the GT just went offroad X with Kooks headers and Corsa Extreme axle backs like I have and it sounds wicked, but you'd never get away with driving it on the street.
 
I haven't heard a car with the full Kooks system and no cats but I'm guessing their mufflers wouldn't be much quieter, if at all, than the Corsas. Probably a no go for your CA tracks with db restrictions.
 
You cannot run a long tube without a tune. Not just for the CEL but for the A/F trim. Your going to lean out the car or throw PO171 , PO174, or PO175 which all are B1, B2 system slow response which means it cannot calibrate the air flow. Tune is needed to adjust.


The BOSS's we have install LT's like American Racing (personal favorite), Dynatech's, or Stainless Works have picked up a good 20-25rwhp gain with N/A applications. With a CAI, you will see about 25-30 and with a power adder, a good 35-40 hp increase (depending on conditions)

Most N/A with the LT's and CAI are around 430-440rwhp
 
In another thread, another vendor claims you can run headers (at least the Kooks) without a tune and the only issue is a CEL for the sniffer due to the cats being too far from the motor. Though I noticed you don't list Kooks. I'm not trying to start an issue, I am just curious whether you have tried running a Kooks as the other vendor is reputable as well.
 
You cannot run a long tube without a tune. Not just for the CEL but for the A/F trim. Your going to lean out the car or throw PO171 , PO174, or PO175 which all are B1, B2 system slow response which means it cannot calibrate the air flow. Tune is needed to adjust.

Absolutely false. No tune is needed. Even if a tune was free, I would strongly encourage owners to stay with the OEM tunes. Both the black key and the track key will run 2/10's to 4/10's RICHER on the stock tunes with the long tube headers.
 

TMO Supporting Vendors

Top