Exhaust Backpressure Testing

[speedybenz]

I have been testing the backpressure on my AMG C43.

I did not start before I chopped off the AMG muffler and resonator though.

But with the Magnaflow "X" chamber muffler with 2.5" dual in and 2.5" dual out where and stock resonator was and then straight dual 2.5" piping out to the bumper I measured 1 psi just ahead of the muffler and in back of the stock cats.

Today I measured the pressure ahead of the stock 2nd cat and found 4psi of backpressure. I believe 4psi is quite a lot of backpressure.

The backpressure rises with engine load and rpm. So at 2000rpm the backpressure is low, say 1/2psi but climbs to say 2psi at 3500rpm and to 4psi by 5000 rpm.

Jeff

[CKlasse]

Are magnaflow high flow cats in order then?

[speedybenz]

CKlasse,

I am not sure what to do. I still have to test just before the precats and the backpressure there could be 5-8psi? Who knows.

I was doing some research and found the 2002 corvettes went from 4 cats to 2 cats and also reduced the backpressure a ton. Picked up 20 Hp.

Maybe I can find these cats in a wrecker yard for cheap.

I have been trying to find out a place to buy metallic substrate cats for a decent price, but then I have not seen any flow numbers.

Jeff

[speedybenz]

CKlasse,

I got the Cat Convertors you sent and installed them this weekend. I did my backpressure testing and found they reduced exhaust backpressure from 4psi down to 2.5psi .

However I still have 1psi at the Magnaflow muffler back the exit point of the exhaust pipes. If I can reduce this to zero, maybe the backpressure at the cats will go down too, as they are located before the muffler.

Thanks.

I will have to check if I have improved on my 0-60mph time of 5.3 sec's.

Jeff

[moebiusgold]

Originally posted by speedybenz
CKlasse,
....
I was doing some research and found the 2002 corvettes went from 4 cats to 2 cats and also reduced the backpressure a ton. Picked up 20 Hp.

Maybe I can find these cats in a wrecker yard for cheap.

I have been trying to find out a place to buy metallic substrate cats for a decent price, but then I have not seen any flow numbers.

Jeff

I think it is illegal to sell cats from a wrecking yard. So what did Ken send? RandomTechnolgies (SP?) or ? Wish you had access to a dyno.

[speedybenz]

Mob,

Ken sent some cats that BMS has custom made by Carsound that make both the Random Tech and Magnaflow cats.

They are nice units and you can see the difference in substrate density while looking through them. Stock cats allow just a very small area of light to come through while the BMS cats allow a much, much larger area of light to show through.

Jeff

[Tump43]

I've got these cat's as well and like them alot. They are noisy but they definately decrease back-pressure and better acceleration times.

MKB makes a similar kit to BMS's with the metalic substate cat's, and the AMG Owners Club board in Germany claims a 20 Hp gain from the MKB system (race cat's, y-pipe replaces center resonator, high flow muffler).

[CKlasse]

Congratz Jeff!

You will find the 'turbine' has about MINUS 1-2 psi backpressure. This vacuum will help those cats tremendously!

I can still ship you some hi flow X or Y if needed.