DoubleNutz

Hey hold up Tom... I wanna be a test bed too

I want one of these pretty badly...when man, when???

Flott Leben

Wouldn't another advantage of a rear turbo over the SC be that a good portion of the additional weight is in the rear? Wouldn't that be better for handling than having the weight added to the front and wouldn't it create more downforce on the rear wheels (almost always a good thing in these cases)?

SharkSkin

I doubt that the rear turbo unit weighs a whole lot more than the original boat-anchor muffler. My biggest concern with this sort of setup would be making sure the oil lines are in the least vulnerable location possible. I wonder how practical it would be to strap them to the TT, up above the heat shields?

atb

Herr Kuhn wrote:
>>>>>>>>>The rear mount turbo should be able to powerfully sting an equally boosted CS car because it will come on full tilt before redline.

Is boost on a dyno an apples to apples comparison when dealing with a turbo v. S/C car? The reason I ask is that the rear turbo car isn't reading as much boost as the S/C'd cars for the level of HP it is making (especially once the dyno tech pulled the A/F probe far enough out of the tail pipe so that it wasn't jamming the exhaust turbine . I haven't seen the dyno sheet for the 400hp run, but they state that the boost meter on the dyno only showed 3.5 lbs of boost.


>>>>>>>>>Blown head gaskets ususlly mean detonation is in the picture.
Curious to see what we'll find when we open her up.

DoubleNutz

So for 3.5 lbs of boost you are getting 400+RWHP?

Blown Head gasket translates to a high probability of detonation? mmmm Adam I heard that the original engine had many issues before the RT went in to the car. Perhaps the RT exascerbated any already jacked up issue. Why not put that thing in a 928 with no issues to get a good baseline from which to work from?

fabric

Actually, they're both wrong. Should be "the car is at my and Tom's shop." The easy way to check your grammar is to drop the proper name portion:

"the car is at my (and Tom's) shop"
"(Tom and) I went to the shop"
"He gave the turbochargers to (tom and) me"

I expect to see no more errors on this particularly grammar point.

DoubleNutz

Hmmmm, good grammer check Fabric...thanks!

m21sniper

"The reason I ask is that the rear turbo car isn't reading as much boost as the S/C'd cars for the level of HP it is making (especially once the dyno tech pulled the A/F probe far enough out of the tail pipe so that it wasn't jamming the exhaust turbine"

That's because the turbo takes so much less power to spin than an S/C does. At any given boost level a turbo will be more efficient, and at high boosts the advantadge starts to become massive when compared to an S/C.

Turbos are banned from NHRA and Formula 1 for a reason.

"Blown head gaskets ususlly mean detonation is in the picture."

Could just be excessive pressure(ie beyond the rated strength of the head gasket) with an otherwise normal combustion process. Det usually involves broken rings or melted pistons moreso than bad head gaskets, at least, in my experience it does.

DoubleNutz

Same here... blown head gaskes where not a proplem for the SC guys until they start pushing 16-18lbs of boost. 3.5lbs to me clearly suggests there is a problem with the engine not the turbos.

Jim Nowak

I didn't know they were banned from the NHRA??? I know that they don't use them in top fuel and the larger engines due to supposed safety reasons but there are NHRA turbo classes. I think there was an issue with the turbos surviving the 4000 degree exhaust temps produced by the nitro-methane engines?

Formula 1: I don't think they are able to run superchargers or NOS either.......

GoRideSno

Here is an apples to apples comparison of an STS rear turbo system versus a KenneBell (autorotor) twin-screw both without intercoolers, both at 6 psi. Chevy 5.3L truck engine. This is the only vehicle that they have in common.
http://www.ststurbo.com/chevy_truck_performance_results
http://www.kennebell.net/supercharge...60/gm48-60.htm

A difference of 4rwhp.

3.5 psi adding ~130-140rwhp is highly unlikely. I won't say it's impossible because I don't "know it all". But that's about a 40rwhp or 30% (EDIT it's actually around 15%...sorry guys, my mistake) of stock HP gain per psi of boost. FWIW anything close to 10% of stock HP per psi boost is a phenomenal gain so 30% is highly unlikely. IIRC I was told a rear turbo 928 made something like 340rwhp on 6psi or 7psi at the Pac NW dyno day some time ago? Is this the same car setup.
If someone gets 400rwhp on 3.5 psi from a stock 928 engine I am going to be in sheer amazement.

Andy K

Jim_H

Everything I have read concerning the turbo vs sc differences are that the sc's are easier on the motor. ?

Imo000

Hmmmm. With the extra pressure of the SC belt on the crank shalft, I would say, if anything, the opposite would be true.

Jim_H

I have not found anything that backs up that claimm though it has been discussed.

From a Doug Hillary post
Usually SC installations are less problematic than turbo chargers as they are more able to be fed lubricant in the ideal operating temperature range and without the tendency for coking as in some TC installations. TC's due to their heat and operational factors, bearing type(s) and location can lead to rapid oil degradation and severe combustion system/piston/ring deposits

Imo000

Ok, I see your point and retract my previous statement.