GoRideSno

Bill,
Do you mean the exact same dyno?
Andy

Bill Ball

Andy:

Yes.

GoRideSno

Bill,
With 262rwhp before and the test pipe added, you could be in the 344rwhp range.

Andy K

Bill Ball

That would be nice.

CMW

Bill,

I agree with you mid range punch is very very very very very fun... very fun.

Bill Ball

I guess I should keep the test pipe on. It's straight through with a glasspack tube in place of each of the converter guts - amazingly quiet, but it should breathe easier and may come to life with the extra air.

GoRideSno

Bill,
If we do a before dyno and it dosen't test as good as last year with the test pipe we could always swap back to cats during the weekend.

YEP mid-range is what makes a car fun to drive.
Andy K

Bill Ball

Hey, Andy:

I'm wondering why your estimates seem low for my S4. Your S4 at 6.7 lbs is producing gobs more power. True, it is intercooled and twin-screw versus Eaton, but I thought at modest boost the Eaton should be pretty close, and I did not think intercooling would produce a dramatic difference at this boost level.

Is it that throughout most of the RPM range the Eaton is in fact very close to twin-screw performance, but it falls off while the twin-screw continues up all the way to redline giving you a higher peak HP, but little difference in low and mid-RPM range where I spend nearly all of my time?

GoRideSno

Bill,
When tested at 6.8 psi non-intercooled Jag/Eaton M112 Stage2 my '87 S4 automatic with X pipe produced 361.48rwhp.

When tested at 6.7psi intercooled Jag/Eaton M112 Stage3 my car made 387.41rwhp

The intercooler added 26rwhp.

When tested at 8.5 psi intercooled Jag/Eaton M112 Stage3 my car made 401.8rwhp.

At just under 7 psi my '87 S4 automatic Twin-Screw Stage2 intercooled my car made 398.2rwhp.

I use 20% drivetrain loss for automatics, and 15% for 5 speeds.

GTs seem to dyno at higher #s than they should, 326*.85 = 277.1 v/s the reported 300rwhp.

Each time I've dynoed my car I have used the Ott X-pipe. I subtract 25CHP from my #'s to make up for the absence of cats.
HTH,
Andy

jorj7

Bill,

344 rwhp should be good up to the 155 mph class of ORR. I had 337 last season. Better
start looking for a navigator. I've got a hundred more now, so I hope to go faster (if I can
get all the safety equipment on). By the way Marc called today and said the rollcage should
be done tomorrow.

Bill Ball

George: I saw your rollcage today - it's a true work of art! One more bar to go in then the new windshield.

Bill Ball

Eww...OK, that's good information on the intercooler effect. And I see the difference between the Eaton and twin-screw in peak HP. I was just woindering if they were much closer down the RPM range as I suspected, based on the general comments I have seen about how the twin-screw differs from the Eaton in power delivery. Hey, it's all good. I'm realy looking forward to the 26th!

Fastest928

Hey, I want to be a stickie too!

Seth W

What is interesting is how little HP there was to gain on Andy's car between 6.8 and 8.5 PSI --only 13 rwhp?? That really can't be the loss of efficiency on the Eaton, could it?? I think what I have read is that its very efficient up to about 10psi.

Andy, why the diminishing marginal return over 6.7psi on your car?

Seth W

bump