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Specs:
WCCH heads
Im not sure if HPR likes to keep their cams a secret or not, so i have a 25x/26x 0.650/0.650 grind
mamo msd intake
1-7/8 arh headers, cats, oem catback
mpss tires @31psi
3.90 gears
baseline was 580/536 with wavy afr and some KR sprinkled in. Once we cleaned up the fuel table and added a little timing up top i got 587/551 but it picked up everywhere as much as 11hp and 15tq.
honestly im a little disappointed in the absolute number but i suspect (hope) the cats are plugged up considering the car dynoed 631 in california on 91 octane and 3.42 gears before i bought it. Ive put about 6k miles on it and havent replaced plugs or done anything else except gears and oil changes.
I couldnt help but compare to the graph fnbadaz06 posted and i made like 25 more tq at 4500 but way less horsepower once things started spinning.
California graph:
Here is mine from yesterday, Blue is baseline, red is last pull
anyway, this is my first time chasing dynos in a car, so roast away
Dynapaks can read higher at times, but that is a fairly big difference at about 7%. I've heard in the 500-600whp range dynapaks and dynojets should read similar, but comparing dynos is never a science. You're better off comparing your car against other C6Z's that have run at the shop in Florida. You might find that it is a stingy dyno.
3.90 gears will put down less power than 3.42's, but again that is a big drop. I'd expect 5-15hp difference maybe at the wheel from a 3.42.
If you have really heavy wheels and tires that can exaggerate the difference between a hub dyno and a roller.
Things to note, power curve looks very stable and healthy. Peak power and torque are happening at the same location between the two dynos. You did get some nice power and torque gains everywhere by optimizing the tune. All very positive things. There's nothing to indicate that anything is wrong with the build. I do however dislike cats, and have seen huge gains in power and responsiveness from removing them - even ones that aren't plugged. They just suck for breathing, and a 468 needs a lot of airflow.
FNBad's build is way more aggressive than this setup from what I recall. High compression, bigger headers, bigger cam, way bigger intake etc etc. I wouldn't compare too much there other than to see what's possible if you go full sausage on mods later on.
That does seem light and it looks like it's peaking early for that size cam and intake. Did they monitor map and see if you have a restriction on the intake? I guess that's pretty good for still having cats and a stock catback. You probably have 30+whp there. If you like it quiet ditch the cats and get some cutouts. It sounded good when I saw you though!
It still drives nice, its really fast around town, and i love the car, but i was hoping for a better number, especially considering the dyno graph from the same car right before i got it. I was definitely happy with the gains and it responded really well to the changes and the fueling and timing cleaned up more and more each pull.
We had a hard time finding a good car to compare to, he mostly had 800+hp ZR1s and 1000+hp ctsvs. he had a ZL1 camaro that was a h/c/i car and ~30hp shy of mine if im remembering right. As far as i could tell its not typically a heartbreaker dyno, but also not a magical RPM one either.
I datalogged all runs and the dyno read ambient at 101kpa and through the run i logged 98-100. unfortunately i didnt get any logs with the car off so i dont know what the e38 saw as ambient. ambient temps were 91ish and my iats were stable at that temp.
next time its on the lift i want to try to inspect the cats. I definitely wouldnt have chosen to install them but i bought the car already built.
Would a giant cam cause the cats to prematurely fail from fuel loading them up over time due to the overlap ? the car spends 90% of its time at cruise and idle. ive never had cats on a fast car before, usually i have down pipes sticking out of the front bumper or bullets dumping before the rear axle.
Last edited by TrendSetter; 07-22-2020 at 06:01 PM.
If cats aren't important to you, 100% remove them. Even if they aren't plugged now they do pose a risk in the future. I've had them plug bad enough to cause a heavy misfire on that bank, and I didn't realize they were plugged until it got that bad. It was night and day after removing them. My buddy had the cheap ARH hi flow cats plug up on him and his car picked up like 20whp from 475 to 495 after taking them off and they weren't nearly as bad as my OEM cats.
A catless X-pipe, or even grafting in a straight section to your existing x-pipe should be pretty cheap. If you're looking for money to spend, 2" headers would probably gain everywhere but I can't imagine it being a huge gain.
The only cats I'd trust in your instance are something like a random technologies or a Kooks green cats. Something really high dollar and high quality. After my OEM GTO cats plugged I put green cats on and ran a ton of miles and they still worked great.
98-100 kpa isn't bad at all. The restriction is almost guaranteed to be at the throttle body. People are spending $1500 on huge southways TB's with the 468's to correct it. A lot of money to spend for what is likely to be a very small gain.
To get more revs out of your combo without going through the hood I think your best bet would be the Frankenstein billet low profile intake. Lots and lots of money, but this is what was on that 800whp STD (more like 760whp SAE, and non oxygenated race gas - still beastly) C6Z. You'd give up some low and midrange due to the short runners, but then pick it all up with way more revs up top likely to the 7200-7500 range. Honestly I wasn't real impressed with the results for the Fast/Holley hi-ram vs the Mamo MSD on the dyno testing that FNBad did, or rather the MSD did really well until it couldn't support any more airflow up top without having to go halfway up the windshield to do it.
You have the 3.90 gears already which will make a higher RPM combo work better. If you imagine that you're not going to gain torque, but just move it around the rpm band by changing the intake - if you manage to move that 500whtq from 6200 rpm power peak up to 7200 rpm you now make 685whp.
Spanks is on point. That kPa is normal for us down here if you don't have a big restriction on the intake side. I definitely think there's more in it if you do the exhaust and ditch the cats.
I am almost certainly going to ditch the cats, i expect thats what is eating up all the power it used to have up top. just need to scrounge up some 3" ss tube, i know i have a little 3.5 from my evo downpipe build.
as for the rest of the stuff.... maybe another day. I accept the 'milder' combo for what it is. I never really planned to replace the intake but would like to do 2" headers some day, but Anthony at HPR was the same opinion, it will help but probably not be a big difference.
the combo is right where it needs to be for my use case, but the top end being restricted compared to when i bought it last year was a little disappointing. i kinda wish i lived closer to my friend with the dyno so i could throw it back on real quick once i got the cats off. I have good logs of the dyno runs so im expecting if it picks up it will show in the hz.
LOL @ 468 and that cam with the term "milder" I'm just messing, now that you listed the cats and exhaust, the numbers don't seem so bad. No cats and cutouts FTW.
I would venture to guess that statement is on a stock cube/Bolton setup, not a mountain motor. Shoot keep the stock catback, kill the cats and add dual cutouts. Have your cake and eat it too.
Word on the street is replacing the stock catback isnt worth power and the npp valves work really well in keeping it quiet on the highway.
There is, roughly, a 10whp difference going from the stock cat-back(which necks down to 2.5" at the mufflers) to a full 3" version. I went from ARH cats to a cat-less x pipe and didn't really pick up anything. Less then the exhaust swap, that's for sure. Unless your cats are clogged, I would say they are not causing a huge loss. I even sprayed when I had the cats, just in case the BuT ItS a HuGe cI eNgInE excuse comes out. Still didn't make a huge difference. Fireballs were bigger with no cats. All my testing was on the same dyno but not same day.
OP, what are your cam specs?
There is more to a camshaft than just specs so don't be afraid to disclose.
I agree with one of the posters that the engine is peaking too early.
OP, what are your cam specs?
There is more to a camshaft than just specs so don't be afraid to disclose.
I agree with one of the posters that the engine is peaking too early.
Come on Bort, put your specs up before he discloses his. That’s too easy...
I said it's peaking too early because a 468 with a 25x/26x with a Mamo MSD and 1 7/8 shouldn't be peaking at 6200... Also not sure if it's Dyno settings or what but losing 50ftlbs at the hit seems odd also.
Come on Bort, put your specs up before he discloses his. That’s too easy...
I already somewhat know what the OP's specs might be, however, I need to see where the valve events are now.
There might not be anything wrong with the camshaft.
I already somewhat know what the OP's specs might be, however, I need to see where the valve events are now.
There might not be anything wrong with the camshaft.
What do you think the valve event need to be? Give it a shot. Never stopped you before...
07-22-2020, 10:51 AM
HPR 468 daily driver chassis dyno 
I'm just messing, now that you listed the cats and exhaust, the numbers don't seem so bad. No cats and cutouts FTW. 
