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Old 10-20-2005, 02:35 AM   #1
Jon B.
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Default Murf 928 vs. Twin Screw

I am planning on getting another 928 here before long and this one WILL be supercharged. It is probably going to be of the 32V S vintage as well. My goal for power will be in the 500rwhp range. Research tells me that the only 928's that have accomplished this are the Supersharks of Tim Murphy. I know the Twin Screw stuff is capable of making this power, but I have yet to see it on a 928. Considering the newest Mustang Cobras make upwards of 600 hp with the Twin Screw Kenne Bell, I don't see why the 928 couldn't. The Twin Screw system that Dave and the gang have now is still cheaper than the Supershark stuff and that is a big plus for me. Eventually the car will have a lower compression 6.4 liter motor to really "Shoot for the moon" if you will. I want something to grow with and either one should be capable of performing. What are the fuel issues that you guys running serious power have encountered? I know that ECU modifications aren't really an answer (at least I don't think). Will I have to go to some kind of Motec or other Stand Alone management? I would really like to see just how far I can push the envelope with my car and have all of you guys on the board along for the ride. Any questions, thoughts, or insight into my crazy ideas would be appreciated. I'm just glad that the 928 is now a car that has the tools to be capable of insane power levels. Should be fun!

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Old 10-20-2005, 02:45 AM   #2
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I made 462 rwhp with the twin screw. This was with minimal tuning and under 7lbs of boost. I will try and find the chart. I have no doubt 500 rwhp is obtainable with the twin screw and will prove it this winter.

It will be interesting to see where this thread goes...
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Old 10-20-2005, 03:17 AM   #3
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Hey Jon,
Good to know there is one more N'thusiast in Austin! Sounds like you've got big plans for boost, but as far as which is better... Do a search and you will find tons of threads on this, some with links and some with LOCKS too!

You see, who has the best way to boost is kind of a touchy subject round here.

Looking into going turbo myself.

ATB,
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Old 10-20-2005, 03:19 AM   #4
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Yeah, you might want to do a search. Tons of discussion of the topic. Many of them chippy.

You're thread title alone is enough to get some blood boiling...
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Old 10-20-2005, 04:27 AM   #5
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The archives could've been searched for this.
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Old 10-20-2005, 04:41 AM   #6
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Quote:
Originally Posted by Jim_H
It will be interesting to see where this thread goes...
Uhuh.
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Old 10-20-2005, 07:22 AM   #7
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I recently PM'd someone about this subject after a comment they made referring to my 928.

I now know why they never responded back to me!!! Im still curious, but not really sure I wanna read it all over again!!
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Old 10-20-2005, 07:53 AM   #8
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Hi Jon,
Good luck with your project, whichever option you go for. As far a fuelling, there are issues with big the injectors you will need for your HP target, as you know.

The good news is that you CAN remap the existing LH to work with these. I will shortly announce the SharkTuner on Rennlist. A beta test version is already in the USA.

But this only applies to LH2.3 equipped cars (MY87 and later)

We have a s/c test car here in Europe running 42# injectors at stock fuel pressure at idle.

Regards
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Old 10-20-2005, 10:02 AM   #9
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Quote:
Originally Posted by Wild Bill
Hey Jon,
Good to know there is one more N'thusiast in Austin!
Bill
Oh yes. There are quite a few more of us. We really should get a manifest together.

500 RWHP would be AWESOME!

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Old 10-20-2005, 11:55 AM   #10
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Since you're in Austin, so is the only 928turbosport! Email me for a test drive later tonight if you want. Also, visit www.928turbosports.com
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Old 10-20-2005, 12:11 PM   #11
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I was wondering how long before the turbo option would hit this thread. Good show Mark. It is usually Goldmember's creator that gets to these things quickly with the other forced induction option.
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Old 10-20-2005, 12:14 PM   #12
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If it wasn't fun, I wouldn't be promoting it. I have both a 928Sc & a 928TS i my garage: turbo is SOOO much more fun/intriguing.
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Old 10-20-2005, 02:26 PM   #13
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Still haven't seen a turbo come close to 500rwhp. Not diss'n, it's just that is what he is looking for AND not to spend a boat load of $.

Quote:
Originally Posted by MarkRobinson
If it wasn't fun, I wouldn't be promoting it. I have both a 928Sc & a 928TS i my garage: turbo is SOOO much more fun/intriguing.
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Old 10-20-2005, 02:31 PM   #14
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The turbocharger promises the least path of resistance to the big top end HP numbers. Also, don't forget that powerband width should be of huge importance to you. Yes, CS have made 500+WHP, but look at the rate of change on the HP curve...because of the boost curve. The twin screw is a far superior machine, thus the reason OEMs use them. If I was supercharging the 928 I would go with Dave's setup. It is clearly the best option for supercharging the shark right now. Next time you look at a dyno graph compare the 3000-6000 range and see the real differences. How many times do you really peg the car to redline? I believe the turbo to be best because it doesn't tug on the crank, nor does it draw of lots of power like the other two options. The real need for boost is from 3000 on up, and that is where the turbo shines the brightest. Remember a CS simply can't make large boost and flow numbers until the RPM is up. It can't change its mass flow rate without the crankshaft speed changing...it is flawed.

Fabrication work has begun on the new twin turbo S4. The goal is still sometime next year and I will be building it onto the stock internals first to search out the limits.
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Old 10-20-2005, 02:35 PM   #15
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Jim...My twin turbo fabrication has just started. There are a lot of doubters on this board about what is possible with turbocharging on the 928. Twin turbos, large flow paths and lots of intercooling potential is a recipe for great results.
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Old 10-20-2005, 02:35 PM
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