Gained 25/25 rwhp/rwtq with 1 3/4" American Racing Headers

Got my dyno results. No other changes except adding headers. Same dyno. SAE corrected. Very similar weather. The before dyno was with stock exhaust. The after exhaust was with ARH headers and stock catback. We had originally planned adding heads and headers, but to be as scientific as possible, we just did one change at a time and added headers only.

The before dyno was 362 rwhp and 353 rwtq. The after dyno was 387 rwhp and 378 rwtq. Although the peak gains were 25/25, just look at the huge torque gains at 3000 rpm. We're talking over a 30 rwtq gain which is going to drop the 60' times in a big way.

For what it's worth, the previous combination with stock exhaust was optimally tuned by James at Frank Racing with his CMR tuning. I ran a 12.49 at 108 mph with the 362/353 combination. The only thing we changed were the headers. The tune was adjusted with the CMR tune after the headers were bolted up. The American Racing headers in 1 3/4" size running high flow catalytics. I wanted to post up these numbers to show that 1 3/4" headers are a very good size for the Jeeps. Just look at the torque gains under the curve. While there have been solid gains with other brands, many of the results posted showed an untuned baseline and then a tuned after-result with headers. My results were tuned vs. tuned. Bottom line, the American Racing headers are for real and a worthwhile mod for our Jeeps.

 

Nice pickup Patrick. The headers look to be very high quality.

 

Here are some photos of the headers installed.

 

Peak numbers never do a thing for me. The over all curve gains are nice.
Good stuff.

 

Good gains Patrick now when you gonna do mine

 

Very nice! Need to get back to the track now. Those results are with your cam too right?

 

Very nice Patrick! I'm impressed at the power made throughout the band. Many people say the true gain from headers is like 10hp. Many say more, so it's nice to see it's on the high end for sure.

 

Nice work Patrick! That 25hp/tq will help tremdously in your 60ft.

 

As I mentioned on the other forums. That is one heck of a gain. What is next?

Did Frank Racing retune this?

 

Wow, 12.49 at 108 means your 60' times were already impressive right?
Did you have to do the collectors yourself?

 

I'm not sure what you mean by that. The entry into the primaries at the flange face of the headers was nicely hand-blended by American Racing Headers. The high velocity merge collectors are a standard feature on the ARH product.

My best 60' time pre-headers was a 1.77. With the weather getting into the upper 80s, it might be difficult to show big gains at the track since my 12.49 was run when the weather was in the 50s. I'll just have to do my best and use the weather correction software to see what we gained at the track.

 

Nice gains!The headers look like an installation night mare.

 

Long tube headers, regardless of brand, are a big pain in the butt to install on an SRT8 Jeep. Much easier on an LX vehicle. For what it's worth, the driver's side header with the 90 was the easier of the two sides to install. It just slid right up. The passenger side was much tighter. I can't imagine how much more frustrating it would be to install the larger 1 7/8" headers on the passenger side.

 

i can tell you that the passenger side is kinda tight. the drivers side after removal of the fuse blocks and the prop shaft you have decent access to the head.

the passenger side while we thought would be a easy fit, turned out to be a harder one. ended up removing the transmission hard line and with a little coaxing, it went in. once its past the pinch point, it goes on easy.

any of you guys wanting to do this mod, when you get with your installer/shop let em know they will for sure need to lift to get it done quick. expect 10 hours of labor for the first install till you learn the process and i would say one could get it down into the 6 hours range if you did enough of them and learned all the "quirks".


steve

 

with it being a PITA that it is would you suggest using stage 8 lockers as going back in to re-torque the bolts after a few heat cycles does not sound very easy

 

That's probably sound advise Wade. It's also a good idea to run the factory MLS exhaust manifold gasket and not the one that comes with the headers.

 

Due to lack of space, I skipped the Stage 8s. It would be a bigger pain in the ass to get clips on than it was to just goback and retorque after a few heat cycles. (So far no leaks after about 1000 miles) As far as a lift, thats personal opinion. I did them in my garage on my back, I dont remember the split but some bolts are accessiable thru the top and others thru the bottom. It was much easier to slide out on a creeper than it would have been to go up and down with a lift.(Plus my arms and neck would get wacked out with the lift) It did take me over 10 hours and that was because it was a learning experience as to which was the best way to access the front bolts on the drivers side. I didnt remove the inner fender but did remove the battery and fuse blocks. As mentioned above after the 1st set you learn what to do and I could prolly do it in 8 hours if I had to do it again. (I wont the buyer of my rig will get Longtubes) Maybe Patrick can comment on the ARs but with my brand Xs the stock manifolds were way harder to remove than the long tubes to install. The stock units are so bulky that accessing header bolts can be difficult on many of the tubes. Also, I personally dont recall having to lift the motor to squeeze the LTs in but I could be wrong. If memory serves me correct, the bolts for motor mounts were a pain in the ass to reach and thats why I didnt do it.


Patrick, once again Im very impressed with your gains. Kudos to you on your research and the way you have decided to tackle your mods. My goals are similar to yours, low to mid range improvments over numbers on the big end. Im curious to hear your opinions on gains, I dont want to even mention the brand of my headers because I dont want to get into brand wars but I only picked up 8-12 thru the entire RPM range. Do you think its the design difference or were your numbers multiplied because of the cam and intake ? Also important to mention, I dont have cats.

Great post and results

John

 

Patrick, I assume you have all your dyno files on disk and can overlay runs as you please. Can you post dyno runs dated 4/20-18:36:44 over dyno run 3/15-20:39:44 ? Comparing these 2 runs you had gains closer to mine but lost 5ftlbs Tq at peak lease: I would like to see the gains thru the curve between those 2 runs.

Here are the 2 graphs I speak of

http://guerragroup.com/ARHdyno.jpg

http://guerragroup.com/3-15-08dyno.jpg

John

 

John is this what you are looking at the one on the left is his Cam dyno the one on the right is his recent Header/Cam dyno

 

John,

The 3-15 dyno, while done on the same Mustang dyno, was measured a different way than the April dynos. Back in March, Kurt did not have a coil pickup to measure rpm for the Jeep and since there are no spark plug wires, we could not use the inductive pickup. As a result, the engine rpm was measured at the rear wheels. While this approach is OK for a tuning standpoint, it skews the torque a little higher because of the slippage between the torque converter and the rear tires. Remember, we were trying to tune the Jeep at this point and were only interested in the delta of before and after the CMR tune.

In April, Kurt received his coil pickup wire and could then measure rpm off the engine instead of the rear tires. We decided do redyno the Jeep before the headers were installed so we would have a new baseline for a true apples to apples comparison. There were no changes to the tune or mods from the March dyno to the April dynos, just the process in how rpm was measured. When we re-dynoed, the hp was pretty close to how it was when measured rpm with the rear tires, but the torque was down. No big deal since we would be basing all future dynos using the coil pickup wire.

If you look, the basline dyno in April compares closer (torque-wise) to the DynoJet run after the cam swap.