Ok - here is an interesting dyno sheet

This car was originally tuned with some minor parts like an intake and a flash - this is the black run 004

Some time later the customer returns and adds

Cosworth cams
Buschur full Stage II with high flow cat
Inclues T/B exhuast - Intake- lower fmic pipe - MBC - pump - 02 housing - flash

This is the red line - 009 - is the tuned pump gas reflash. I felt the car was on some real weak gas and it was having small knock counts even with a very conservative tune. I wanted to rule out any issue with the cam install - e.g. engine noise - (flase knock) etc so I poured in some 100 octane unleaded fuel

Run 010 green - nothing changed - just the 100 octane fuel - the car goes 100 % knock free and holds timing

Next - we felt that the high flow cat may be the culprit holding back the power so we drianed the 100 octane fuel out and then we got some fresh pump gas and installed a test pipe

Run 011 is the run with pump gas and the test pipe - No tuning of boost changes

I thought this was an interesting dyno comparision

I then retuned the car and it was done

AL

 

370lbs ft on pump gas with a stage 2 car? What's that in dynojet terms, like 430lbs ft, right?
Wow!

 

Our DD is calibrated to reads very closly to a dyno jet

More important than the peak numbers is the difference between the test samples

 

Besides the obvious power difference, look at the freakin spool difference with the test pipe. That's like 370wtq @ 3000rpm, wtf! Bonus!

 

So al.. the cat was causing the knock.. Im guessing the car wasn't liking the back pressure?

 

I had this problem with my car. my car hated the high flow cat i had on there. as soon as i added a test pipe, it ran like a new machine.

 

that is some real nice power!!! good job al as always

 

Nice post, good information!

 

How much boost?

 

I would not say causing knock

It is more like an exhuast restriction creates additional un-needed back pressure which results in ineffective exhuast gas evacuation fron the cylinders

This condition enahances the tendancy to knock

IX Evos are very senestive to knock

 

The TQ is fantastic but how come the power drops off so much after 6200? Shouldn't it be able to at least keep peak power to 7000-ish?

 

What correction are you guys adding to do this? 1.15?

 

I believe they are using 1.10 correction. Stock Evo IXs put down 240ish whp on that dyno. Other DD dynos in New England seem to read fairly close.

 

The boost was tapering down to 15 psi

Also- as mentioned above the car was very knock prone

I think the final tune was flater - keep in mind this is a interim testing not the final tune

I will print off and scan the final dyno sheet later tonight

 

Correct 1.10 is what we have found most accurately corelates to DJ #'s

The main use of a dyno is to measure what happens between one run to the next