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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Some of you may have remembered my CPR HCI build last year. Main mods from stock were Pfadt 1 7/8" headers w/catted x-pipe, WCCH redone heads, Katech K501 cam and cleaned up MSD intake. Link to the full build below. I have had quite good results on several performance events with that build including in 1/2 mile roll race trap speed (800'elev.) and 1-mile standing start trap speed at 6500' elevation.
The results of that build were interesting with 602 rwhp @ 7100 rpm and low 489 rwtq using SAE smoothing 0. After the build I got many comments about the headers contributing to the odd results. I decided to have CPR replace the AFE/Pfadt headers/catted x-pipe with ARH 2" headers and catted x-pipe. In addition, to create a little more headroom on the fuel side CPR installed ID 725 injectors.
My goal was to pick up torque in the 5000-6000 rpm range and keep my power but drop it down into the 6700 rpm range. That should help me in my goal to break 200 MPH at Mojave in the 1 1/2 mile standing start event, hopefully next spring.
Keep in mind these are on 91 octane gas with a 91 octane tune by NicD.
A scan of the dyno runs CPR did this week are below"
The comparison of the changes on this dyno (different from the dyno last year) show a very good increase in torque and a reasonable increase in power and at a lower 6700 RPM, just what I was looking for. On last year's dyno the 602 SAE smoothing 0 would be 595 SAE smoothing 5.
When I get the dyno files I will overlay the plots from last year's dyno on these CPR dyno runs.
Congrats on the results Dave. I followed CPR on fb and saw the post earlier today.
This is really great data to showcase the difference between the headers, since there weren't any other changes affecting power production.
That low speed torque is just killing the tri-y design!
CPR understood my interest in providing good data to the Forum so had planned to do the before dyno run on their dyno to give apples to apples comparison. Also the test conditions for June 2016 and this week were very similar resulting in the 1.04 to 1.05 correction (low 90's ambient temp).
I didn't know that was you there dropping it off or I would have said hi. I have the base dyno run on my camera.
Joe said the arh fit a lot better than the other headers. This backs up what I've seen time and time again. That the pfadt make 15-25 less than a solid 4-1.
Very impressive results Dave! That dyno curve is simply fantastic. Should really prove now that a better set of 2" headers does in fact make a measurable difference, with the right supporting mods. You are twisting about the same torque as me over the same portion of the band, but with more power. And I'm on 93 octane. I'd really like to know your dynamic compression ratio. I assume your bottom end is stock? Much thanks to posting. I'd be interested in your results on the track. The kind with turns.
Very impressive results Dave! That dyno curve is simply fantastic. Should really prove now that a better set of 2" headers does in fact make a measurable difference, with the right supporting mods. You are twisting about the same torque as me over the same portion of the band, but with more power. And I'm on 93 octane. I'd really like to know your dynamic compression ratio. I assume your bottom end is stock? Much thanks to posting. I'd be interested in your results on the track. The kind with turns.
Thanks, I don't know much about dynamic compression ratio. WCCH milled the OEM heads .030 so normal CR should be about 11.7, then NicD tuned for 91. I figure get the heads milled and if the car gets sold to an area with 93 that just a retune would be necessary. Bottom end is stock with ~53K miles on it.
Road circuit results will have to be seat of the pants type as I do not often time laps with the Z. I do know the last couple of times I had it our, both stock and after the CPR build that my now 3 year old R888s did not hook as well as before even though they have not been heavily heat cycled. I have been able to hand time laps from my videos
You also have to think it was a hair cooler for the 10am Pfadt run, than the 5:30pm ARH run the next day. I would love to see this same comparison on a FBO ZR1.
The overall gains are nice, but the gain below 3500 is incredible! Maybe I never understood it correctly, but I thought the purpose of tri-y's was low end torque.
Exactly what I see time and time again. ARH 2" is the way to go. Kind of funny too since the entire marketing behind those trick Ys is that they make better low end and midrange power.
just to make sure im reading this right the comparison of the two,they were taken on different dynos AND a year apart?
These above are same dyno one day after another, correction 1.04 on the cooler 10AM run w/ Pfadt (run 10/2/17) and 1.05 with ARH (run 10/3/17).
My prior build thread was on a different dyno and was SAE Smoothing 0. When I get the dyno run files from CPR I will do a few other dyno graphs that will compare the two different dynos and log them as SAE smoothing 5. The HCI w/ Pfadt were run on both dynos, primary difference was 6K miles on the build on the latest run on CPR dyno.
10-05-2017, 01:24 AM
Pfadt 1 7/8" vs ARH 2" dyno results
