Fogey1

I'm really tech-ignorant in this topic and have no desire to start a micturation contest, but I was reading through a recent thread about turbocharging, thought about the rear turbocharging thread and wondered :

If mounting space and heat are a problem for close mounted turbos and turbo lag would be a problem with rear-mount turbochargers, might it be possible to use a small rear mount turbo that fully pressurizes the intake by, say, 1500rpm and a waste gate that releases intake over-pressure all the time (instead of venting exhaust gas, right?). Heat and lag solved! I'm confident there's a reason it wouldn't work.

As for acceleration times, 0-60 is fine but I'd rather know 10-50, 20-70, 50-90, 70-110 and the like. Seems more real world to me.

tomboyea123

I did 60 - 130 in 12.4 sec at 9200 ft in my blown shark.

IcemanG17

Will
look back a few days for the 60-130 post that Tomboy put up it had some good data in it...there are several older 0-60 or 1/4 miles posts that are really good as well. Tony has great data from his G-tech that can tell you almost anything you want to know!

GoRideSno

Ther is no accurate way to measure any span that does not start at 0mph.

Andy K

GoRideSno

How about 0-113mph in 12.43 sec.
I have done 0-60 in 4.3 sec.
So it stands to reason I can do 60-113 in 8.13 sec

HTH,
Andy K

Tony

This is some GTECh data i have on street tires and 91oct . Just toss in some basic Algebra( sorry for the profanity ) and you can get 30-110 etc

Herr-Kuhn

The reason the rear mounted small turbo will not work well is because to generate boost at 1500 RPM, the turbine would be very small....it then becomes a big restriction at high engine airflows. You have to be tolerant of some amount of lag with the turbochargers, but all in all it really isn't bad because you are starting with a V8. You want to have lots of boost from 3000 +/- on up, that is where most of your driving is done. The other option would be a variable geometry turbo that essentially changed the a/r ratio as the loads come up, that is what most diesel turbos are these days.

I ran 5.2 seconds 0-60 with the G-tech on a twin turbo 1980 with 3-spd AT and a 13.6 1/4 mile at 108 MPH on the G-tech, same car. 10 or so lbs of intercooled boost.

mspiegle

0-60 in 4.8 over here

truvkngfan

Made it to 60 yesterday, quite a bit of tire slip and still hit 4.2, I'm guessing in the high 3's with drag radials.

Fogey1

Tony, that looks like about 5 seconds 30-80. And 4.5 20-70. Ballpark is good enough for gross comparison. Thanks.

Andy, I figure you'd need a fifth wheel, like the car mags, to get really precise. And I'd expect autos to perform better b/c of the downshift. I'm not going to racing anybody away from a light, but it's always nice to reel 'em in and/or leave in the dust from a roll-on.

Herr Huhn, I figured that exhuast restriction through a small spool would be the Achilles heel of my cool running, cheap plan. Oh well.

GoRideSno

Perform better than what?
Andy K

Fogey1

Perform better than a five-speed in a roll-on from a moderate speed, because an automatic would downshift when it went to WOT.

GoRideSno

The 4 spped we have will never perform better than a 5 speed.

Andy K

Herr-Kuhn

Automatics....UGH what a pathetic transmission for a 928.

Jim_H

The 4 speed is the best automatic I have ever driven and when used manually is fun.