SROC276

So today I had my car dynoed for the first time. Great weather in Sonoma, around mid to 70's. I followed another forum member and set an appointment with Works Performance. They use Dynapacks.

My cars background: daily driver, 40k miles, p31 package.

oetune stage 1, row boxes with afe drop ins, ram air, renntech shorty headers into stock primary cats, high flow 200 cell secondary cats into full IPE cat back. No other mods internally. Car just had heads worked on to replace buckets and she received new cams due to timing adjustment problem. Adaptations were reset 400-500 miles ago.

*i could not reflash to stock tune because I didn't bring my loader. Sorry no baseline improvement.

My test was just to get a power reading. We did it with valves closed then open. 5 pulls were made and were consistent so we stopped.

IPE valves closed:

Drum roll please.....

327hp & 340.1tq........

IPE valves open:

414.8hp & 398.7

*with valves open there was an 87.8hp diff. This exhaust was designed to be run with lth in closed form IMHO. You would actually loose some power compared to a stock exhaust when it's closed.

glennhl

What that tells me is the IPE cat back is terrible with the valves closed but awesome with them open. It also puts to rest the old urban legend that modern day injected engines need back pressure.

SROC276

I agree on the back pressure issue. Thinking it's my secondary high flow cats is causing the issue. There are folks buying the rear on slip ons so that set up technically would be worse than my set up in a valve closed scenario.

mr747

that is a massive gain with them open cant believe it

glennhl

Do the IPE valves bypass the secondary high flow cats?

I had an electric cutout on a 2001 Z28. I had a decent cam along with long tube headers. The cutout was downstream the high flow cats but upstream the stock Camaro cross flow muffler. Those old Camaros did not have a true dual exhaust. The muffler had one inlet and 2 outlets. Not a great system. Car dynoed 386 rwhp with the cutout open but only made 352 rwhp with it closed for a loss of 34 rwhp.

I thought that was bad, but your loss is way too high.

SROC276

No the IPE valves are located in the rear muffler section. Yes it's a big loss in power so will try and figure out a solution soon. Thinking something else is off due to general power even with valves open. I was expecting at least 430 or so with it open so 414 was a disappointment. Not sure if it was a dynapack reading (different from dynojet). I was noticing a slight loss of power when I got the car back recently from the valve job work so I re flashed the car when I got home. I'll drive around a bit to see if that improves the situation on my *** dyno. The power does match up mathematically with my et times (12.56 @ 119mph) using a hp calculator so we shall see.

Kriston

Pretty decent numbers bud.


After reading your mod list, I am convinced that shorty headers do not make any power now. Try shooting for a Long Tube header setup. Atleast with the shorties they aren't too difficult to remove.


My mods are very similar to yours.
Renntech Intakes + AFE Dry Filters / Secondary Cats Deleted + Eisenmann Race Exhaust + Eurocharged V5 Tune.


I put down 440 WHP and 390 LB FT TQ After Tune
Base lined the car without the Tune at 390 WHP and 375 LB FT TQ


Temp was 73 Degrees, and were at 550 FT above Sea level.

Merc63

A bit of back pressure helps exhaust flow at low rpms.

It's generally not needed in most cars as you're never driving full throttle at 2000rpm. That's your cruise area.

glennhl

So the problem is downstream of the valves meaning it's the IPE mufflers. I would have a tendency to go to another dyno and repeat the testing. That 88 hp loss is so hard to believe. And if it repeats I'd throw the stock cat back back on and see what it dynoes.

SROC276

cant argue with that but if the 414 open number is good then the lower closed valve output was also good cause he pulled it 2-3x. I know it had less power than stock just buy driving it but didnt know how much less until now.

SROC276

Update:

So I forwarded all my dyno pdf's to jeremy at oetuning. he was quick to respond. I told him a week or so ago (before dyno) that I felt the car was a little sluggish in 3rd compared to before. We both assumed it was the adaptation reset done by dealer when they replaced my valve buckets.

After the surprising dyno results, he asked that i reflash the car to stock and then back to the stage 1. Once completed, the car is now pulling like a freight train again. I am guessing and I think my tune may have been wiped at dealer or an update from them scewed the tune if at all possible.

AFR was 13.8 so running lean. Jeremy is sending an updated file to see if we can sort out AFR and richen it up a little. I may dyno again in Sept.

-Marlin-

I don't know how to put this in a way that won't come off rude.

All that money in mods and little improvement over stock. Dollar per horsepower gain is not good.

glennhl

But even with a good tune there is still something badly wrong with those IPE mufflers. There might be a broken loose baffle in the muffler that is blocking flow when the valves are closed.

SROC276

Very possible....no difference in power though since day with valves closed. They always felt slow with it closed vs open, so I got used to keeping them open during spirited drives. Normal cruising and traffic it is left closed so for a year and half I didnt think anything of it.

I am guessing those with long tube will always make more power than stock so even with it closed it wasnt noticed? Then again I havent seen anyone test it closed like I have so cant compare.

SROC276

Well I am pretty sure the car is now faster when I reflashed it last night. Pull is way back so I am thinking will dyno again in the next 2 weeks or so. My gut tells me there was no tune or something was altering it after i got it back from the dealer. If we assume no tune then 24-25hp for the add on's (header, cat back and row boxes) to the wheel is not bad considering I didn't pay retail and in certain cases got steals for parts except my AFE filters lol.

I agree the dyno results were a disaster! Will be back shortly to repost. So far the reflash has helped get some major grunt back so I am at least happy about this.

SROC276

Here's another dyno for an IPE system for C63 w/ stock tune closed and open:

Stock tune - non p31 is 312whp w/ valves closed. Open it jumps to 356whp.

With tune - non p31 is 451 whp w/ valves open.

-Marlin-

Just curious, did you ever get a base line tune of the car bone stock prior to any mods on the same dyno?

SROC276

Unfortunately no, first time to get it dyno tested since I bought the car 3 yrs ago. If we use stock baselines of 385-391 on a dynojet not a dynapack then we can go from there. Been reading up on Dynapacks and some say readings are 5-10% lower than a dynojet! not sure though. My baseline is the other c63 which was a stock p31 with a tune pulled 420+ hp. So I know something is off with my car.

SROC276

Sorry a little late to respond. Yes our set up is similar other than the intake. I think the shorties do help in power especially torque as I could feel the difference. For the price though may not add that much compared to lth. Luckily I bought my set new at a liquidation sale so I got a massive discount on them. Essentially same price as a new PLM header and they were new. It's a happy medium for those looking for a little extra but don't want to remove the primaries. My torque was around 398-399 range on the high end, just hp low. Oetuning said I was running lean so waiting to get a fix in shortly. Adding a little gas may help the top end. Thinking my stage 1 tune was wiped form the car after the service at the dealer. Just noticed it was slower and 3rd gear pulled flat. They told me it was adaptation, but after my reflash and power changes with my *** dyno, thinking there wasn't a tune.