Catback HP increase??
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Originally Posted by mikejofgb
Actually 350 rear wheel is equal to 412 at the engine, as to account for 15% loss you divide rear wheel by 0.85, not multiply by 1.15.
A) that 15% is the number. It's not. That's just a rule of thumb - no magic to it.
B) that all dyno's are exactly correct. They are not. That's another reason why using a factor is just a rule of thumb. Engine dyno's can all vary, and rear wheel dyno's can all vary.
Instructor
Joined: Mar 2005
Posts: 151
Likes: 1
From: Green Bay WI
Originally Posted by jschindler
Here we go again. You are assuming:
A) that 15% is the number. It's not. That's just a rule of thumb - no magic to it.
B) that all dyno's are exactly correct. They are not. That's another reason why using a factor is just a rule of thumb. Engine dyno's can all vary, and rear wheel dyno's can all vary.
A) that 15% is the number. It's not. That's just a rule of thumb - no magic to it.
B) that all dyno's are exactly correct. They are not. That's another reason why using a factor is just a rule of thumb. Engine dyno's can all vary, and rear wheel dyno's can all vary.
I'm not assuming either (A) or (B), only assuming that you divide by the "number" (12% or 15%) rather than multiply by the "number" (12% or 15%).
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
Folks there is another factor to consider when conducting "before and after" dyno pulls. If the LS2 responds like the LSX motor's (and I've seen this many times over the years) you run your car, get a base line, make a change and make another pull. Since the computer hasn't had a change to "re-learn" and make it's minor fuel trim adjustments you get a "temporary" lean condition which yields a false positive reading. You would need to get the base line, install the mods drive the car 50 to 75 miles then re-dyno. Suddenly the BIG gains disappear.
BTW I just dyno'd my :bolt on" only 03 Z yesterday with the following results:
I didn't get to do a baseline as I bought the car with the B&B PRT's and Bassani x-pipe exhaust in place. All I added was the Blackwing. Not bad for $1500 in bolt on's. I need a tune, my AFR's were horrible. Considering how rich my car is, I bet I would have seen some HUGE gains had I done a baseline, changed the exhaust and dyno'd right afterwards (mechnically leaning the motor).
So you have to know how the before and after tests were conducted.
Tom
BTW I just dyno'd my :bolt on" only 03 Z yesterday with the following results:
I didn't get to do a baseline as I bought the car with the B&B PRT's and Bassani x-pipe exhaust in place. All I added was the Blackwing. Not bad for $1500 in bolt on's. I need a tune, my AFR's were horrible. Considering how rich my car is, I bet I would have seen some HUGE gains had I done a baseline, changed the exhaust and dyno'd right afterwards (mechnically leaning the motor).
So you have to know how the before and after tests were conducted.
Tom
