I have a 2008 C63. I have added the Kleemann shorty headers & high flow cats, the ECU flash and Kleemann European airbox covers. I had the car dynoed on a on a dynojet and it only put out 400hp. I was expecting a higher output. I made the mistake of not first baselining the car prior to the mods, but there's nothing I can do about that at this point. I am trying to figure out why my car is not putting out more power. One thing worth noting is that during each pull, as the car approached redline, the air/fuel ratio got extremely rich. Is this a case of a dyno error? Has anyone had the experience with this type of scenario? I appreciate any insight, as this is getting frustrating!

Thanks!
Andrew

What where you expecting

HP on a spec sheet does not equal HP on a dyno.

That number sounds a little low to me, but I am not an expert so dont flame me.

A DynoJet usually reads about 10% higher than a Dyno Dynamics dyno.

If you see the posts below as an example, a tune only C63 should get 400-425hp.

With headers and an airbox I would be expecting at least 450.


OR

https://mbworld.org/forums/c63-amg-w...velopment.html

Without a baseline, it's tough to tell. Read outs can vary on the same brand of dyno from shop to shop.

I think Vivid estimated about an 80hp gain after the tune, headers, full exhaust with cat elimination, etc.

Hey Andrew--did you re-dyno on a reflash only after we tested together? Also, are you sure the shop that installed your new Kleemann mods had the ECU reflashed?

You have aftermarket high flow cats? I have CA-legal primary cats. The difference between primary cats and test pipes in their place was about 20HP on a Dyno Dynamics. Your cats must be worth at least (-)10HP IMO.

What's extremely rich? My M5 ran very rich (approx 10.3:1 at redline). Retuned to the 12.4:1 range resulted in an increase of 11HP, again on a Dyno Dynamics.

Hopefully Sincity chimes in, he may have the identical setup as you and did "before" dyno runs so his delta will be useful.

Agree with this statement I gained about 87hp with those mods.

Hey Alan,
Yes, I had it tested again after having it reflashed. I know the ecu was reflashed, as I set it up with Corey at Kleemann. He recently pointed to three things that could cause the lack in power. they were the purge valve, crankcase breather valve and intake manifold gaskets. The dealer told me that they replaced the breather valve and manifold gasket, but I'm not sure they know what they're talking about. I wont go as far as saying I dont trust them, but I just got the feeling they were bullsh#!ing me. They told me the oppostie of Kleemann. They said that the only thing that could go wrong with the purge valve is that it could stick open which would cause the car to run lean, not rich. This is making me nuts!

I was expecting at least 420 range. Even Kleemann said that 400 was low, I'm just looking for more insight into what could cause reduced power with these cars.

Take it to the track and then you will know for sure.

My car dyno'd really low when I had a tune on it as well.. It was a low reading dyno.. I took the car to the track and it was right where it should be.

20hp? That could be one of a number factors as to why the dyno read low - temp, humidity, how many runs you did, how and when it was last calibrated, gearing, the tech, etc.

A a purge valve stuck open would cause a CEL, as would bad intake manifold gaskets. Doubt those are causing your issue.

The cats with the K2 manifolds are 200 cell per Corey.

Andrew, You are running a bit low. I did about 423WHP on a DJ with the K1 tune, ROW airbox tops and K&Ns. I haven't ran a dyno with my K2 exhaust manifolds and MBH X-pipe yet. I've seen another member from the past with just a K2 setup at 445WHP on a DJ. Can you post your dyno sheet?

Sorry about the delay posting this - Please let me know any thoughts - I appreciate it.

You're running pig rich in the upper RPM and its probably costing you some HP.

See your torque curve drops off hard as it starts to get too rich.

You should be 12.5-13.0 AFR at WOT.

What he said.

Get a dyno tune done and have them free up some of the hp through the band. You may gain some horsepower (10-15whp) . You'd be surprised how constricting the primary catalysts are...