Gregg K

Daammn! That is nice. Congratulations on what appears to be a very nice piece of effort.

I know one thing, if I come into some surplus cash, you'll have a customer.

Ed Scherer

I've gotta say: aesthetics on Carl's SC kit are second only to the 928SP twin screw, IMHO. Intake is really nice. I suppose it's a little superficial, but hard not to notice. Thanks for checking in, Carl.


And that reminds me... (might be a dangerous topic)... what ever happened to the 928SP twin screw? Seems like its been unobtainable for a really long time.




Oh, and thanks for the following replies related to my concerns about aging head gaskets when boosting. I guess I won't worry about it.

Carl Fausett

Yes. It may have even been 2004. I developed my first supercharger kit for a 16v 928 in 2001-2, that one fit under the motor in the spot that was occupied by the air conditioner.

Customers wanted to keep their AC, so I re-designed and came out in 03-04 with a top-mounted supercharger that allowed the AC to stay in place and function. This is the kit I debuted at the 928OCIC
in Kansas in 2004.

Its hard to keep all the iterations clear, and there was a lot of "destructive" early development early on. We were finding out how much boost a stock head gasket could handle, how much fuel a 928 fuel system could deliver with and without mods, and a million other things.

The Powerdyne comments are not applicable. We have never made a kit for a 32v 928 that used a Powerdyne. They have all been Raptors.

blown 87

It is the detonation that kills the head gaskets.

Jon B.

I've got a question for the Murf guys. Does anyone have a good picture of the supercharger bracket with the tensioner/rollers? I'm curious about belt wrap with the boost levels the stage 3 is seeing.

hacker-pschorr

+1

Another example of putting way too much emphasis on boost levels.

Over the years I've been contacted by a number of non-Murf boosted 928 owners who damaged head gaskets or worse (pistons) with moderately low boost levels.
They all had the same question, what did I changed in my motor to run 16+psi on a bone stock 1981 US car. The answer? Nothing.

No secret, just a an emphasis on tuning, data-logging, and a lot of time on the dyno.

I was told I am either lucky, wasted a lot of time / money on sensors & dyno time, my car must be special etc....
Someone even shared with me an e-mail from a known 928 tuner who claimed Tim Murphy and I are liars, our motors must be custom built to handle "that much boost".....you get the idea.
I was told a particular tuner knew the "secret formula" because they have damaged a number of 928 engines under boost. Well I guess that's like picking a doctor with the highest number of dead patients.

Iwanna928

What do you call the guy that graduates LAST in Med school?...........Doctor

Imo000

Wooooow... Now this looks intersting and dead simple too!

928mac

I have to agree hacker that a boosted engine can not have the stock timing and fuel mixture or detonation will kill it.

A easy remedy for this is methanol-water injection. Most pro shops will suggest it.
http://en.wikipedia.org/wiki/Water_injection_(engines)

It cools and It increases octane

Rob Edwards

Hey!

AO

You win.... :roflamo:

hacker-pschorr

Methanol injection is a valid approach, I wouldn't call it easy.

Todd was never satisfied with the "off the shelf" applications with his red supercharged car which had the capability of meth/water injection early on with that project.

He's taking a different approach with his twin turbo that will make use of extra channels in Autroinc to control when and how much meth is injected based on a few different parameters.

Carl Fausett

+1

Dont forget, even a engine with retarded ignition timing can be made to have detonation with the wrong A/F mixtures. Its a factor, but its not the ONLY factor.

hacker-pschorr

He never said timing was the only factor.

Spark plug with too high a heat range - which is why I recommend at least one heat range colder with all boosted cars.
On high boost cars projected tip plugs can be a good source for pre-ignition detonation
Cam timing off
Faulty cooling system causing the heads to get run hot (reason why Todd runs his engine as cold as possible)
Extremely high exhaust back pressure
Dirty combustion chamber is also a good way to melt an engine from pre-ignnition
Bad / old - low octane gas
Blow-by with a inadequate separation system causing excessive oil to be ingested by the engine. This is a fun cycle since detonation is a good way to cause / increase blow-by.

Just to name a few........

auzivision

I like these debates. It allows noobs like me to learn a few things.

From what I remember reading, the primary 'ping' factors are charge composition (temp/pressure/air/fuel) and ignition. There are a number of things that can affect both of these.

Intercoolers are keen to keeping the charge cool (so is running richer). It would seem that a cold air source would be high on the list too. Then again the Porsche engineers deemed the top of the radiator acceptable for stock, so it might not be that big of a deal.

Then, I remember a conversation with my brother in law, an automotive engineer for GM, and this subject has been studied fairly extensively. He stated, the biggest problem is heat radiates forward and in order to get constant cold air draw, they needed a snorkel about a foot of two in front of the bumper. I’m pretty sure this was for stop and go driving and once up to any speed most of this goes out the window.