Lagavulin

Not according to the dyno runs I've seen; an RMB is worth zilch. However, I do agree that the car sounds like it has at least an additional 10 rwhp. Most do not realize the S4+ rear muffler is a straight pipe with holes in it like a MagnaFlow or DynoMax muffler, and likewise nil restriction compared to a baffled muffler.

GoRideSno

Tim,
Thank you!


Sorry to disappoint but there was absolutely no hardware change. There was not a pulley change not an exhaust change, nothing.

Could the belt have been sliping in 02.......






Lag,
If this dosen't agree w/ your math I would have to say that you are not taking a few things into consideration. I guess I would be looking at the Vortech Mondo Igloo intercooler and trying to figure out why they actually replace the upper half of the manifold w/ an IC.

All runs were at LESS THAN 7psi.

Whay size is the IC core that Don is using in his setup?


Andy K

Tim Murphy

Why would I be dissapointed?

My intercooler cores are 4.5x4.75x10.75
This size core seems to work very good for me. This will actually keep the intake manifold cool to the touch, even on the dyno.

Tim

http://www.murf928.com/photos/dyno1.gif 8psi, Ott x-pipe, RMB

GoRideSno

Sorry Tim,
You shouldn't be. That actually aimed to Poke fun at Lag. He seems to take it personal when people present info conflicting to his sometimes, like with the whole motorcycle race thing.

That is the size IC I thought you were using, Very good choice.

Andy K

Tony

Lags, hopefully i can answer.
From what ive read and understand about the Twin Screw type SC is that they are very sensitive to restrictions upstream of the intake lobes of the SC. The more you free up the intake (reduce pressure losses) the less the SC has to work to get those losses back. . If that makes sense???Something like that at least.

This is one of the reasons i went with the intake you may have seen in my previous posts. (Plus its got a coolness factor which we all know is good for 10hp : ) ). A straight , short 90' run to the fender is what im trying. While Im sure there is nothing wrong with the intake Andy is currently running , his chart speaks for itself and his methods, i wanted to play a bit and experiment with it. "We wont know until we try" is my approach to a lot of this stuff.!!! I just felt that the routing and the source of air could be improved. Now that i have a 4inch hole in my fender i guess im committed! I made it 4"+ as I eventually would like to try a Ford 105mm TB and a larger MAF like Mark Anderson has experimented with and see what that does? Right now though, for me, that is putting the cart before the horse.

I tell ya with the work thats going on between everyone boosting one way or another, there really is a revolution going on in the power potential of the 928! You and Murph have already shown what it is capable of!

Tony

Edit..Double post.. Sorry.

Lagavulin

No, it has nothing to do with the math. I'm just looking at the runs on the chart that you posted, and noted the 20 rwhp difference throughout the entire range between run #002 and runs 012 and 014. They are all mirror images of one another except for the 20 rwhp disparity. Typically, tuning changes will not look that way since it's more of a give-and-take thing, especially when altering the fuel pressure with the stock fuel maps.

It's really beside the point anyway because all I was saying earlier was, take out the x-pipe, and both cars ran EXACTLY as expected given their respective blowers. The twin screw has the advantage down low, and centrifugal the top, with the crossover occurring at 4000 RPM. It really is a great comparison, but could have been better if both had the same exhaust one way or another.

Well, that's probably fair, perception-wise. If I remember the gist of that conversation, it had to do with power delivery under race conditions which I'll still stand by. 'Race RPM' is between 4000 RPM and redline. Anyone can look it up, and it is where track-type races are won or lost since RPM will not dip below 4000 RPM once under way. 'X' amount of extra horsepower below 4000 RPM will not help one under race conditions if it comes at the expense of the same amount of horsepower above 4000 RPM where you really need it under those circumstances. I know it's pretty basic stuff, but some like to argue otherwise nonetheless, and evidently I'm up for it too! If I do not sway nor budge from that accepted fact, or if I staunchly defend it's position, it's not because I'm taking it personal.

Enough of that; again, nice runs!

By the way, where did see that an RMB is worth 10 rwhp? There was a thread on that recently where everyone ageed that there's no gain to be had.

blau928

Hi Lag,

Intake item is heavily documented by Kenne Bell. www.kennebell.net They do what Andy has done to the 928 with Cobras... Exactly, his manifold is a version of theirs. They also use the Autorotor...... Hmmmm.. And have gotten 700+ RWHP from a Cobra. Tony was on to the logic, as the less restriction on the intake side of the compressor = less restriction throughout the system. This is one of the setbacks I saw with the Centrifugal designs. Where the air intake, filter and plumbing will be located.

Try a dyno run without the filter, just a 4 inch pipe, and compare to your run with filter and pre-compressor plumbing...... just for kicks....

EHP is Engine/Crankshaft HP

KLEEMANN is a Danish Tuner of Mercedes Cars. They have exclusively used Opcon products (Autorotor/Laminova) in their designs, and have the land speed record for a 4 door sedan at 338Km/h from a twin screw E55 AMG. I got the research and proof on Autorotor stuff from them initially, and Mc Laren confirmed my other theories.

The car should be ready by June 30th if all is well. however, it is still a ways off. Most of the work is custom as you know, and it is slow going. I want to do this only once. At least now the exhaust is now done.

The water temp as close to or below ambient is very agreeable by my research as well. The water flow rate and the I/C radiator size and thermal efficiency is also big.

I am also ecstatic that Andy has switched to the Autorotor compressor after we discussed it in depth. His testing has confirmed what is possible with the 928 32v engine.

Andy,

I was aware that you are using the same exchanger as Pro ECM. David and I spoke for a bit on this as well. I have chosen to go the Marston route, as I wanted a bit more water capacity in the system, and this is the biggest unit I can physically fit in the nose of my car.

If I can end up with 500 RWHP at .7 Bar, I will also be VERY pleased. I also plan on keeping the AFR in the 12.5-13:1 range, as I think the coolers are oversize enough to allow this. However, the move up will be in small increments, as the motor has 210k miles as of now...

The baseline of 268hp/282tq was pleasing as well (without the new exhaust syatem). I will dyno again next week with just the exhaust system so I can see what gains I have from it.

EspritS4s

Richard,
Why do you feel that the Autorotor is superior to the Whipple?

Thanks,
Gary

blau928

Gary,

No feeling on the Autorotor vs te whipple, the compressor efficiency map proves it. The machining tolerances on the Autorotor are much finer than the whipple.

The Autorotor is a more finely crafted, precisely machined piece of machinery.. This is what changed Andy's mind after we spoke....

GoRideSno

Gary,
Both the Autorotor and the Whipple will fit on the system you have. They were both designed by the same company, have similar dimensions and the same bolt patern.

After having both the Whipple 2300AX and the Autorotor MX22 on my car I can say that I would be happy to have either, but I prefer the Autorotor.

At full load, i.e. making over 700hp, the Whipple has a very slight thermal advantage, but the Autorotor has a lower drive power, about 8 less HP required to turn it.

KenneBell claims the Autorotor is more durable, because it has bigger bearings and the casing is CNC machined instead of cast.
HTH,
Andy


Now should go down to Carlsbad dragstrip today?