ErnestSw

I've posted the results of adding the Motorsports X-Pipe with their cats and an RMB showing about a 20HP gain. Today I dynoed the car with the X-Pipe, no cats and an RMB (stock cat back to RMB) and there was NO difference!! Still around the 310HP mark with about 300ft lbs of torque. The air fuel ratio was still very rich above 5000 rpm at around 10:1.
The car is quite tame at idle, but without the cats the term "loud pedal" takes on new meaning!
On the one hand I'm disappointed that there weren't any more ponies to be found and on the other hand it appears that the cats flow very well indeed.

BC

10:1 is too rich for high HP, but I assume you know that. WAY to rich. I think your giving up power being that rich.

ErnestSw

No question I'm giving up power, but the interesting point is that there's no gain with "test" pipes. I plan on adding engine management next.

MarkRobinson

what was your AF with the before exhaust? If 13:1 during peak hp/tq, then there's your missing power.

ErnestSw

The air fuel ratio was exactly the same with the cats. I'm wondering whether my MAF is beginning to lose bandwidth.

Imo000

It's not a fair comparison if your engine isn't running properly. Fix the rich condititon and repeat the tests.

James-man

Can someone please post an Exemplary Air Fuel graph?

This will help those that intend to dyno tune a bit.

Thanks!

ErnestSw

WATCH MY LIPS---THE AIR FUEL RATIOS ARE THE SAME WITH AND WITHOUT THE CATS!
SHEEEESH!!

justin

.........and what pretty lips they are!!!! LOL

ErnestSw

Why Justin, I'da never guessed!!

Giovanni

Go back to the stock setup and redyno.... compare results with 1st dyno :-)

Imo000

YES, I KNOW THAT. IN BOTH CASES THE ENGINE IS RUNNIG WAAAY TO RICH.

Let me explain it a little simpler. Imagine your engine is an athlete. With it running rich it would be an athlete with a flue. Now, if you give stereroids (X- pipe) to the athlete, do you think it will show improvement?

To properly test the X-pipe, get rid of the rich condition. Nothing kills HP faster than a rich condition.

the flyin' scotsman

Ernest, I believe Dave Lomas did post his dyno results for both scenarious; with and without 'Cats'. You may want to do a search a nd see his posted results for comparison. Obviously your car requires 'tweeking' elsewhere.

My car with the Motorsport X, no cats, GT resonators and RMB is running too lean and thats with GT eproms and a rebuilt (John Speake) MAF.

So you like the sound???...........I love it

James-man

I am somewhat confused by these results. As I understood it, opening up the exhaust will tend to result in a leaner air fuel ratio. After opening up, things are rich? Was your car super rich to start off with? But, your dyno results look very very good.

Is your air filter clogged (dumb question of course), what gives? This is all very confusing.

ErnestSw

As I said, I wonder whether my MAF has lost some bandwidth.