supercharging the 928

[Guest]

Something to frighten the 911 boyz...
have done the SC conversion on my 5.4 and ironed out the niggles
like air leaks and sliping sc belt, she is now running really sweat
here are some dyno figures i came accross in the US

pretty impressive stuff...
bare in mind they run 91 octane fuel over there as well...

DynoJet Results
order of results :
Owner/Model Ground HP / Ground Torque - Flywheel HP / Flywheel TorqueMods note : Efficiency = 85% 5-Speed 80% Auto


Tim Murphy 88 S4 5-Speed 526 / 486 - 618 / 571 (Supercharged, Intercooled, Dastek, 30 lb injectors, belt slip cured)
Joe Fan 88 S4 5-Speed 500 / 436 - 588 / 513 (6.5L/Headers/Exhaust/Threshie Intake0
Paul Grabowski 87 S4 5-Speed 492 / 445 - 578 / 524 Tim Murphy Supercharger Kit, RMB
Mark Anderson 88 S4 5-Speed 485 / 434 - 571 / 511 6.4L/2600 Lbs/Extrude Honed/80 mm Throttle Body/Threshie Intake
Marcus Hutchinson 85 S Auto 480 / 520 - 600 / 650 F.A.S.T. Supercharged
Dyno Performance 97 Viper 6-Speed 476 / 476 - 560 / 560 K&N, Corsa Exhaust
Tim Murphy 88 S4 5-Speed 463 / 441 - 545 / 519 Supercharged, Intercooled, Dastek, 24 lb injectors
Devek White Car 88 S4 5-Speed 449 / 467 - 528 / 550 6.5L/Intake/Cam/Heads/DasTek/Headers/Exhaust
Mark Anderson 88 S4 5-Speed 436 / 434 - 513 / 511 6.4L/2600 Lbs/Extrude Honed/80 mm Throttle Body
Clay Zbar 87 S4 Auto 352 / 434 - 440 / 542 Nitrous (150 HP Jets)
Randy Page 87 S4 Auto 344 / 315 - 430 / 394 Supercharged, Intercooled, RR FPR, 30 lb, RMB, Cat Bypass
Mark Kibort 86-87 S4 5-Speed 335 / 334 - 394 / 393 "Holbert Car",#004,Devek Level II Headers,3.5 " Race Exhaust,Airbox Mod,No MAF Screen,RR FPR, 86 Clutch,2800 Lbs

 

[Brett928S2]

Hi Rich []

So my aim of 500 Rear wheel HP for my 16 valve S2 DOES seem possible

Is that 85 S a 16 or 32 valver ???

All the best Brett []

 

[Mark_Bennett]

ORIGINAL: 928strosek

bare in mind they run 91 octane fuel over there as well...

Octane ratings in the US are not equivalent to Europe. 91 in the USA is near to 98 here.

 

[Brett928S2]

Hi Mark []

Well I am going to supercharge mine....and its done 120,000 miles....some of the American 928s on RENNLIST have done it at 150,000 plus miles...

Damage....not unless you already have a problem....

As a Supercharger is driven by a pulley from the crank...the power is there from idle upwards...as against a turbocharger which has to spin up to speed first...

A supercharger is relatively unnoticeable until you boot it....apart from a whine on some of them

But,,,you can get at least 100 hp easily possibly 150 to 200 ....on TOP of the 300 (roughly) you have now in a 928....

Hope this helps Brett []

 

[Guest]

there has not been a street car breakage on any of the SC kits put on to 928s as far as the US list go and there have been conversions as early as '94... if there is a weak point it's the head gasket, Paul Anderson had a SC'ed 16 valve in ther with blown gaskets, but a well maintained engine can take the stress, with no worries, i'm runnig 8.5 psi intercooled on a modified S4 5.4, and she is really smooth, a hand full but smooth.

i would recomend it as she now goes like she looks...

 

[Guest]

...also did not know about the differnt octane rating either, i have been
compairing apples with doughnuts on the US list then...

cheers Mark.

 

[sawood12]

If it's anything like modding 944 turbo's the thing that breaks engines is not necessarily the manifold pressure, it is the heat generated by forcing extra air into the cylinders and the fuel delivery system not being able to cope resulting in the mixtrure leaning out and heating up!! So look into larger injectors, higher pressure fuel systems and everything else that goes along with that.

 

[Guest]

yep, agree with all that, hence changed to red injetors, intercooled and upped the fuel pressure.

 

[Brett928S2]

Hi Rich []

What effect did the blower have on your fuel consumption ??

My S2 gets around 15 in town and 21 on the motorway...

All the best Brett []

 

[Guest]

uuhm, yes, that is the down side.... 7-9mpg in town, 15 on the M-ways
but in the cars defence i'm not light footed...

 

[Brett928S2]

Hi Rich []

Good for you

I hope 1 day you can give me a ride

All the best Brett []

 

[Guest]

I just came across this forum and topic, and thought I'd add some information.

Most of the horsepower numbers listed at the beginning of the thread are somewhat old. Both Tim Murphy and Paul Grabowski live in my area, so I'm familar with their cars, as well as a number of other supercharged cars that are scattered across the country here. Tim's last dyno numbers were 556rwhp/496rwtq, and even those numbers are rather old. Tim's car should be right around 600rwhp in it's current configuration, still with the 5.0 liter engine. Paul's last numbers were 513rwhp/469rwtq, with the engine being stock except for the supercharger and the removal of the cats. Both of them are based on the supercharger kits that Tim developed and sells through:
www.murf928.com
www.928motorsports.com

Marcus Hutchinson's '85 S was a 32 valve engine that had been rebuilt with lowered compression. I don't think he owns the car anymore. There's some information on it at www.marcus3.com/porsche_page/porsche_page.html

The stated octane number here is the average of the RON and MON numbers. (RON+MON / 2) The difference in the stated octane number here is supposed to typically be right around 5 less than what you'd use there. In other words, our 91 octane is typically the same as your 96 octane.

There has been engine damage done to several street cars that were supercharged. The types of damage on various cars included blown head gaskets, broken pistons, cracked and also distorted engine blocks and heads. The incidences of damage on the various cars were the result of improper tuning, poor system design or installation, and basically running too much boost for their configuration. The incidents that I'm aware of occurred either during testing on the individuals own car, or with kits that are no longer being sold by their developers. The only kits that I'm aware of that are currently being sold here are through the two web sites I mentioned above, and there has never been any engine damage with any of those kits that were sold to customers.

There's another supercharged 928 owner that lives within walking distance of Tim's home who is also involved in the testing, development, and fabrication of some of this stuff. His initial engine was 5.0 liters, used 951 pistons for lowered compression, and was run at up to 26psi of boost. That's 26psi above atmospheric pressure, not 26psi absolute pressure. His current engine is 6.1 liters and supercharged, and he's currently working on one that will end up somewhere over 7 liters and also be supercharged. He also has a gear splitting unit he modified and installed, giving him eight forward gears with his automatic transmission. Externally the car looks completely stock and is driven to work daily, except during winter.

 

[928S4racer]

ORIGINAL: 928strosek
... if there is a weak point it's the head gasket, Paul Anderson had a SC'ed 16 valve in ther with blown gaskets,

Sounds like the one thats now got no compression /blown head gaskets again