924Board.org

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Min, head-lifting results in the same symptoms as failed head-gasket.

When considering some serious boosting on a 2.5 NA engine, it's kinda obligatory to use 951 pistons+forged rods

_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Min · Posted: Fri Feb 09, 2007 5:40 pm Post subject:

special-tool · Joined: 08 Jul 2005 Posts: 64 Location: Bethel, Ct.

That's right.
It looks just like a burned gasket, but when you take it apart, you see no carbon traces and deformed (pushed out) fire rings.
The other telltale is that after you blow the expansion cap, the car is FINE!
You can drive it away. If you burn a gasket, you can't drive the car - well you can, but you will pull coolant into the cylinders at idle and wreck your rings. You will also leave a trail of smoke like Kimi Raikonnen behind you.
This video is my car making 500 plus at the wheels with head lift, watch what happens......

http://media.putfile.com/special-tools-543-hp-dyno

The car has stock 951 crank, rods and Mahle pistons in this video. You can see the bottom end isn't the problem when you use the 951 stuff.
My crank is exactly the same as the 86 NA, only rods and pistons are different.
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951 566/485 HP/TQ at the wheels - pump gas
924S GTR conversion project
Honda 250R- PWK 35mm flat slide, 205 static, Boyesen, Wiseco, DG front/back, Uni, 14/42,

OutOfTheBox · Joined: 31 Mar 2006 Posts: 434

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Min · Posted: Sat Feb 10, 2007 2:52 am Post subject:

Glen931 · Joined: 11 Mar 2005 Posts: 52 Location: Grants Pass, Oregon

Special-tool Its nice to see someone running high boost on a 951. Iv been posting on clarks garage (front engine porsche forum) and everyone with a 951 keeps saying they cant take much boost. If you dont mind sharing what all you have done to the engine and drivetrain can you pm me with some info so we dont hijack this thread. thanks

Sequential injection allows you to adjust how much fuel is put into each intake runner which will allow you to tune each cylinders A/F ratio seperatly. Due to difference in flow of different intake runners the actual ammount of air that gets into each combustion chamber may differ slightly. basicly it lets you do more fine tuning when you are pushing the limits.
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"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine

Min · Posted: Sat Feb 10, 2007 4:18 am Post subject:

Min · Posted: Sat Feb 10, 2007 4:20 am Post subject:

Min · Posted: Sat Feb 10, 2007 4:24 am Post subject:

Also, http://www.sdsefi.com/techseq.htm

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Actually, I am relaying information from our old hot headed friend "Sequential". He may a bit of a a$$-O but I think he knows his stuff. He once mentioned the 931 as an example. As is known, the 924-931 have a heat problem on #4cyl. Not a problem unless you are trying to ring every last ounce of HP from the motor. With sequential you can add a little fuel or pull a little timing from just this one cyl while still creating max power on the other 3cyl without sacrafiecing reliability.

In a street situaition things are not as consistant day to day with differing weather, fuel quality, carbon buildup, etc.... so we have to run a little richer and pull more timing anyway just to be able to run every day without re-tuning. We make this sacrifice for drivability.

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

Min · Posted: Sat Feb 10, 2007 5:48 am Post subject:

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

One more thing: sequential fuel injection allows to alter the injection angle which results in more efficient burning (=fuel economy) and maximum torque.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Oysteinrb · Joined: 21 Oct 2006 Posts: 47 Location: Norway