str8six

Hello everyone. I am new to forum and was hoping you might have some insight into why my HP seems to be dropping off really early on my recent dyno.

I picked up a 2009 C63 with 40k miles in June and have been gradually modding. Today I had the guys at Kleemann install their Long Tube headers and I flashed my OE stage two 91 tune and it was immediately put on the dyno. My torque numbers are right in line with what they should be but my hp curve falls off really early and is actually couple points lower than my torque.

If you compare my runs to the OE/Gitanni headers dyno I have attached, my torque is almost exactly the same but it looks like i'm missing out on about 40 or 50 hp up top. My tune only run has a similar hp fall off, only not quite as severe.

The dyno at Kleemann here in Colorado reads a little low, but my baseline was within 1 or 2 points of other stock C63's that they have run. We are at 6500+ feet and the dyno is corrected for altitude. My only other mods are ROW air boxes with AFE Pro Dry filters. My AFRs were about 12.2 at WOT on the dyno. These runs were done immediately after the car was flashed with no adaptation miles..

I have emailed Jeremy at OE about the issue but in the meantime I would appreciate any ideas.

Kriston

Interesting find indeed,


I assume you dyno'd the car on 2 different dyno's? That has to be taken into account as well. There will be variances in your readings.


Any particular reason you switched out the Gintani headers to Kleeman?

QWKSNKE

Sounds like it is in the tune. 12.2 is a bit rich for a NA motor.

Merc63

Show us a pic of these long tube headers.

Your car needs some time to adapt as well, but this will most likely not fix the issue.

12.2 is fine, a tiny bit rich, but I doubt you would lose any power at 12.2

Put some miles on it and bring it back for a dyno. Those headers might not flow enough on the top end to bring the numbers up.

QWKSNKE

Do these motors like to run that rich? My experience with na motors is that optimum power is had between 12.9 and 13.4. My boosted cars were tuned to 11.8 - 12.2

Ingenieur

13 is too lean
12-12.5 is optimum for a street car, pump gas ( 91 oct in this case), relatively high comp ratio, and 6500' asl
I would sacrifice some power to preserve the engine

The top end may droop a bit but the toque band is elevated AND widened
How often do you drive at > 6500 rpm and for how long
Vs 3000-6500

The tune looks good
Headers usually cost a bit of low end
But you now have the pre mod peak torque 800 rpm soon snd hold it 1000 rpm longer
It has almost doubled the power band

QWKSNKE

13 is to lean because of the altitude? All of my tuning experience is based at 1000' asl and less with american muscle cars. Of course it also depends on what the car likes as well.

QWKSNKE

Oh and I agree about the wider torque comment

str8six

Thanks for the replies..The dyno with the Gitani headers is not of my car. It came from the OE tuning blog and is from one of their cars. I just posted it for comparison since it has similar mods and the same tune.

Here is what the headers look like.

http://catalog.kleemann.dk/catalog/h...r-kit-204-156/

I didn't get get any pictures of the install but I can see that they come all the way out to the secondary cats. The primary's are gone. (Sounds incredible and very loud

Here is my baseline stock dyno vs tune only dyno for comparision. It was done a couple weeks ago on the same dyno. Again it was done immediately after flashing the tune from stock while on the dyno with no adaptation time, but you can see a similar hp curve

One thing of note is that prior to getting my baseline dyno, I was running OE's E30 tune with about 33-34% ethanol using E85 and 91. The car felt noticible quicker and more aggressive than with the pump gas tune but my Torque app(android bluetooth OBDII scanner) showed my long term fuel trims at around +23-24%. Probably because of the extra volume required of E85 vs gas.. I don't know how accurate the readings are, as i had no codes or CEL and the car ran great. But, it had me a little worried so I went regular gas with the 91 tune and LTFTs eventually went down to +10%. However last night on the way home from the dyno right after the stage 2 91 tune and headers my LTFTs were back up to around 16%. I probably need to reset adaptations but I think I need the dealer for that. I don't know if a battery disconnect will reset fuel trims?

I also wonder if limited airflow was a factor as they only had 1 large room fan along with one of the smaller dyno fans in front of the car? I will try to get to another dyno next Thursday or Friday and post results.

The torque curve does look good, but I thought is was strange that torque was slightly higher than hp, as you don't typically see that with these engines.

I do drive mainly up to 6500 rpm, but have a long empty rural highway I drive to work and get it to redline a couple times on the way.

Would bad MAF or O2 sensors play a role?

SALES@OETUNING

CAN logging data - TPS, IAT, IGN ADV, MAF, EGT etc, is needed to best understand what is going on during these dyno pulls. We consistently see power pull all the way to redline when 63AMG M156 is setup right and running correctly. More information is needed to give a definitive answer and move forward.

Mort

I think a bad MAF sensor or O2 sensor would give you a code.

SALES@OETUNING

Logging is not for code reading rather seeing the operating data real-time. If a sensor is not in the acceptable range of operation a CEL may not be present or triggered. Real-time data is the best and only way to diagnose engine operation.

str8six

Yeah, the comparison OE dyno I posted shows power going up all the way to top. That's why I suspect the issue is probably not tune related but perhaps some something mechanical, or having to do with the dyno or altitude. Going to try to get some logs while on different dyno next week.

str8six

Wanted to thank OE for the quick response, as always. I sent them an email late last night and had a reply this morning when I woke up. I also have an OE tune on my wife's 650i and am thrilled with it.

HardC63

Cool deal!

It sounds to me that your tune needs a little adjustment after the header install. I'm sure Jeremy will sort it all out for ya.

And yes, 12.2 is little rich for an N/A set up. N/A AFR usually lies between 12.5 and 13.0. Most N/A set ups respond best with a little fatter mix right around torque peak (12.4 or so) between 4,800 and 5,250 then leaning out a little on top...most like a steady 12.7 AFR from 5,300 RPMS on out.

Keep us posted

AMG6.3

Based upon your numbers your power is not much better than a tuned C63 without headers based upon your graph. Take car to the track to see how car runs and traps for speed.


I am willing to bet that your high elevation corrected numbers are still low if you compared to a much lower elevation.

BLKROKT

Did this ever get resolved? I'm having a top-end power issue on my headers tune also. Ran an 11.9@116mph the other night. Picked up over 4mph in the 1/8th over stock, but still trapping the same in the 1/4. AFRs also around 12-2-12.4. It's a bit of a headscratcher for me, no codes and otherwise runs great, just falls flat after 100mph. Would be good to hear if you fixed this...

str8six

Not exactly resolved, as I have not been back to the dyno or track..

I sent some logs to Jeremy using the torque app with an obd bluetooth adapter. Everything looked okay in the logs, but the sampling interval that the app is capable of is only every 400-500rpms. He said I would need a real CAN logging tool that is capable of sampling every 20-50 rpms for him to make accurate adjustments and I haven't acquired one yet.

However, at the time of the last dyno, I was switching between an 30% E85 tune and a 91 tune, so I'm not sure if the 91 tune had fully settled in. I was also wondering whether the thin air at 6500ft might be limiting top end power.

Shortly after, I replaced my secondary's with an H pipe and stayed with 91 tune for a while and the car seemed be pulling much harder. The difference post headers with WOT 3rd to 4th and 4th to 5th upshifts is no joke.

Since the car has been running well and feels strong, I haven't been all that motivated to pay for another dyno, but I hope to get to a track soon to get some times for comparison.

RNS-11Z

Str8six you said you ran e85, is your car tuned for it?

str8six

Yes, an OE tune for E30: E85 mixed with 91 to get 30% ethanol. The E85s higher octane(105) and resistance to detonation allows for increased timing. Jeremy said he has run up to 50% E85 with no issues and it gets you another 20-30whp.