Cadillac CTS-V Forum banner

1 - 20 of 115 Posts

·
Premium Member
Joined
·
14,086 Posts
Discussion Starter #1 (Edited)
Disclaimer:
This thread is for informational purposes only. There have been many questions about "How much power are headers worth on our cars?" and as it so happened, I was in a position to try to find out. This thread will NOT guarantee you XX gains, nor will it differentiate between brands of headers. Many cars are fast, and there are many ways to be fast - this thread is NOT about being fast: Simply put, this thread is about comparing headers to the popular factory exhaust (with cat-delete). I will be stating all dyno pulls in "RWHP / RWTQ" format.

Background:
I own a 2013 Manual CTSV Wagon. It started with a Mamofied throttle body and an Airaid CAI. I had a cam and pulley "Stage 1.5" completed on February 20th @ Cincy Speed for my Stage 1.5. The cam is a mild version of LT1z' popular Stage 2. We made several baseline runs and dyno'd again after the 10.5" lower, LT1z cam, BTR springs and Trunion upgrade were completed. The primary catalytic converters were removed and straight-pipe was welded in, however no other exhaust modifications were performed (we left in the Secondary Cats). Those runs will be listed below:

02/20/15 baseline (with Airaid, Mamofied factory Throttle Body): 495/460

02/20/15 final numbers after cam, pulley and cat-delete: 610 / 581*
* Boost was just under 15psi, as expected.

Although I had planned to keep the factory exhaust, the SOUND of the primary cat-delete was horrible, so within days I had placed an order with American Racing Headers for 1 7/8th primaries, X-pipe and mid-pipes into factory mufflers; and I had them drop-shipped to Calico Coatings for their standard black "ceramic" thermal coating. ARH stated that they had updated their hi-flow converters in 2013 after having issues, with the new variants being rated for 2400* EGT, or roughly up to 20psi boost. I also ordered 2.5" Magnaflow resonators (turned out to be a mistake) to help quiet the car while keeping factory mufflers.

One month later, the coated headers arrived literally on the day of the install. Cincy Speed went to some length to humor my needs here, and we were able to "baseline" the car again a few times as I wanted to account for warm weather changes. We did notice belt slip with the factory upper pulley whenever the belt was "cold." so many of the dyno charts will reflect this. However, the first runs were often the best due to colder IAT2. Per my build thread, I expected to gain around 25 RWHP and lose a pound of boost - there is quite a bit of discussion on the what-if's in that thread that I will link below that are good to ponder.

03/19/15 "Baseline" to account for weather: : 610 / 565 (same RWHP, but ~15 less RWTQ as previous best)
03/19/15 Final numbers after ARH 1 7/8" coated headers with cats and dual 2.5" resonators into factory mufflers: 653 / 634*
* Boost was just under 14psi, as expected (around 13.8psi).
* Total Gain: no less than +40 RWHP, +50 RWTQ,using "best" runs from each session.

Dyno Graph:
Note how the powerband is actually more broad than baseline - if the peak numbers shifted higher, it's only by a few hundred RPM?


Key: Run 08 was the 2nd baseline run (the only without belt slip). Run 11 was our best and final run of the day.

Notes:
Dyno tricks, tunes, and AFR:
* The Calibrator stated only one-half degree of timing was actually added, and only above 5K RPM on the retune.
* AFR was highly consistent, and ranged from 11.2 - 11.5 on all runs (tailpipe). Best power was around 11.2 AFR.
* When comparing baselines and mods, all numbers were SAE correction on the same dyno, with the same tuner.
* The correction factor was almost identical for all runs: surprising shop conditions were highly similar from February (Correction factor 0.99) to yesterday's March runs (Correction factor 1.00). This explains why peak RWHP was essentially identical one month to the next.
* The tuner was not aware of any "wager" or purpose to the test, other than to see what headers would bring to my Daily Driver.

My Choices for Exhaust:
* The factory exhaust is cast iron, and approximately 1 3/4" primary diameter. The OEM converters are 600 cell.
* The ARH hi-flow converters were changed in 2013, are 200 cell and rated for 2400 degrees. ARH estimates no more than 5RWHP parasitic loss, probably closer to 2-3 HP at my levels.
* I went with ARH 1 7/8" primaries as conventional wisdom suggests a 2" primary may be "too big" - I suspect 2" headers may be even better, or at least pose no significant loss in my situation.
* The 2.5" Magnaflow resonators are actually a bottle-neck! We placed them right after the ARH X-pipe, and had to weld 3" pipe OVER the 2.5" ends to mate things up. So the ARH 3" X-pipe is going right into a 2.5" lip (the resonators), then back to 3" pipes into 2.5" mufflers! This was an oversight on my part, but we had to make it work due to time constraints.

Final Thoughts:
* Clearly, the factory exhaust was a significant restriction at 600 RWHP.
* I made +40 / +50 with one pound LESS boost: "More power, Less Boost, Less Heat." The final numbers are irrelevant, the DELTA is what counts!
* My cam likely contributed to these huge gains; however +30 / +20 was seen on a pullied, factory cam V (HauvaSteve).
* I would never want to attempt this install in a driveway, on jack stands!
* Anyone who wants to run resonators: ARH is 3" diameter all the way back! 2.5" resonators do NOT fit (even though we welded mine in).
* Your mileage may vary! Brand/design of pipes, primary diameter, converter brands, tune and conditions all may affect your results!


Links:
My Build Thread: Stage 1.75 Header Comparison Blowout!

How Much Power Can Stock Exhaust Handle?

HauvaSteve's Kooks Headers HiFlow Cats Install Project thread

Thanks!

Run 000: That morning's second baseline; First run was higher (610 / 565) but doesn't look pretty due to significant belt slip.
Run 010, 011: Final two runs after exhaust buttoned up.


Update 02/20/2017: The x pipe (with cats) failed on me yesterday, and Mike @ ARH says the warranty died as soon as I had them ceramic coated. I've been happy with the subsequent two years of performance from these headers, but based on the succinct lack of customer service I can't say I'm really pleased with ARH going forward. I would have expected better service from the rip-off resellers on ebay (ie at the least a replacement part at-cost, or something).
 

·
Premium Member
Joined
·
6,875 Posts
As stated there is no better before/after comparison that this. Dyno before on the same dyno same day and dyno after same day same dyno. Can the stock manifolds make power and loads of it? Of course, but you ain't making 650 rwhp with these mods on pump 93 so it shows headers are worth the cost and $60 resonators can be added to keep the same exhaust tone.
 

·
Premium Member
Joined
·
14,086 Posts
Discussion Starter #3 (Edited)
Final Run from February: 78*F shop, 29.59 in-Hg pressure, 5% humidity. SAE correction 0.99

All runs yesterday in March: 84*F shop, 29.48 in-Hg pressure, 7% humidity. SAE correction 1.00


Also note: on all dyno runs, the Wagon was at full operating temperatures for safety. There was no more than 5 minutes inbetween the final 3 runs, no icing, no glory runs, etc. The only reason some runs were used over others was due to the significant belt-slip we were getting on a "cold" Gates belt - which prevented a pretty graph plot for comparison.

That is why you see me using the "peak numbers" from each install/tuning session (apples to apples), but those do not always match the photos I posted (pretty graphs for analysis of curve shift, etc). And, as noted, timing, AFR and shop conditions were highly consistent among ALL pulls.
 

·
Premium Member
Joined
·
14,086 Posts
Discussion Starter #7
Are you going to try again with 3 inch resonators?
I was joking around at the shop about my OCD and how quickly I'll be swapping them out. We're going from 3" pipes to a cut-off 2.5" resonator just under the transmission, so I know that can't be helping any with flow. But with such surprisingly good results as-is (and with a slightly grumpy wife), the swap will not happen anytime soon. But who knows!

One thing I do know: I'm glad I spent my money on this exhaust instead of a ported blower! However, I will probably try to do a ported snout comparison just for fun over the summer.
 

·
Super Moderator
Joined
·
8,604 Posts
I will probably try to do a ported snout comparison just for fun over the summer.
I'd really like to see this to know if it's worth my time/money.
 

·
It's got 7" pistons!
Joined
·
8,370 Posts
So, just to be clear. You went from factory exhaust with secondary cats & crimp, to headers with no cats and aftermarket mid pipe?
 

·
Premium Member
Joined
·
14,086 Posts
Discussion Starter #12
So, just to be clear. You went from factory exhaust with secondary cats & crimp, to headers with no cats and aftermarket mid pipe?
I went from factory exhaust with primary cats cut out, while keeping secondary cats & crimp, to 1 7/8" headers WITH cats and 2.5" resonators spliced in-line where the mid-pipes go.
 

·
Premium Member
Joined
·
2,535 Posts
Thanks for posting this. It mirrors my experience as well but is helpful to have from a third party since some people tend to take anything a vendor may say with a grain of salt. Headers are worth it if you have a pullied and cammed V, period.
You were one of the people that suggested headers and no cats for my build. I listened. Thank you!
 

·
Registered
Joined
·
2,127 Posts
After my results today I should probably call it quits while i'm ahead...

Mike @ New Era Recommended ARH. Says of all the headers they've installed they fit the best. He also said stainless works typically require a little tweaking to fit right one way or another...

Stainless Works can be had for 1350-1450 and ARH seems to start around 1700-1800. I'm going catless either way so that saves some.
 

·
here nor there
Joined
·
4,201 Posts
Full TriTexan, you never go full TriTexan
 

·
Registered
Joined
·
2,127 Posts
ARH all day. Kooks second
That's what it's looking like to me. I don't mind paying for a quality product.

Any substantial benefit in going with 2" over 1 7/8" ?? Car is not likely to be modded any further after headers for the foreseeable future and the headers themselves cant happen at least til after June 27th.

All Bets are off if I put the turbo bike up for sale though.
 

·
Registered
Joined
·
1,946 Posts
Sticky imo
 
1 - 20 of 115 Posts
Top