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Lol you think it is still 6.5:1 CR? I have built 911 engines for several years and trust me, there is just crank and engine case that remain stock (and heads, though modified) at these power levels. Usually 8.5:1 CR is chosen and twin plug that is essential for such kind of build. Right now I am kind of involved in 964 build that consists of 4.0 crank, xtreme heads, Pankl titanium rods, custom JE pistons and VEMS twin plug COP (12x) from me, aim is 1200+ rwhp.
Think 25 psi on 91 octane. And four valve per cylinder. Low Cr will only help me get high psi out of my turbo. It's ok, you just don't see what I do. It much more complicated to deceibe all the workings, when I see it perfectly. It a track car that not going to see much low RPM's.
Quote: It much more complicated to deceibe all the workings, when I see it perfectly.
May be complicated, but not to some of us posting, trying to help. Seeing these motors with reliable 500whp/tq is easy, doing it with reliability isn't.
Hope to see your videos of you taking with a phone in your car soon. Cracks me up one of the vids is upside down, no I wasn't inverted. This motor has more hp/tq off boost than a 968, with a stock 968 Turbo S HG the CR is close to 9.0.
None "that I know of or would trust" modern 930 air cooled turbo engine builders run less than 8.0 CR.
George D, I wasn't needing help. I was asking the question has anyone used a 928 4v head for a turbo build? And so far the question is no. I'm not concerned about "off boost" power. It can be more gutless then my regular 86 944. But when the turbo kicks in, I want to see 25 PSI and 500+ HP. That is my goal. Why? Because Race Car! And I want to show everyone it can be done so they have another option on an engine build if they chose too. I believe many think I'm all talk, but maybe looking at photos of my car should explain I am a very serious 951 owner. I have rebuilt everything on the car. EVERYTHING! My current 951 engine pushes 299 to the rear wheels with a 20+ year old autothority MAF setup and kkk26-8 turbo. That's max for that turbocharger. So I have a LR super 53 to install on this build and I want to max it out as well. i know I need exhaust valves in the 928 4v head, better rods, list off many other items. I'm hear to help as well, not ask for help. I can figure it all out. I worked on a fleet of 30+ million $ Longbow Apache Helicopter as an electrical/armament and avionics system repairer in the ARMY out of FT hood TX when they first arrived in June 1998. MOS 68Y. These cars are easy!!! and I've owned 7 of them, the first 951 in year 2000. I'm running 7.53 CR and high boost on this build. If anyone want to follow then by all means I will help answer any questions to my build. And after this I'm building my 2.7L 8v turbo for my daily driver. But first things first. If anyone wants to help they can offer me parts at a cheaper price!
Last edited by Humboldtgrin; 08-29-2015 at 12:24 AM.
George D, I wasn't needing help. I was asking the question has anyone used a 928 4v head for a turbo build? And so far the question is no. I'm not concerned about "off boost" power. It can be more gutless then my regular 86 944. But when the turbo kicks in, I want to see 25 PSI and 500+ HP. That is my goal. Why? Because Race Car! And I want to show everyone it can be done so they have another option on an engine build if they chose too. I believe many think I'm all talk, but maybe looking at photos of my car should explain I am a very serious 951 owner. I have rebuilt everything on the car. EVERYTHING! My current 951 engine pushes 299 to the rear wheels with a 20+ year old autothority MAF setup and kkk26-8 turbo. That's max for that turbocharger. So I have a LR super 53 to install on this build and I want to max it out as well. i know I need exhaust valves in the 928 4v head, better rods, list off many other items. I'm hear to help as well, not ask for help. I can figure it all out. I worked on a fleet of 30+ million $ Longbow Apache Helicopter as an electrical/armament and avionics system repairer in the ARMY out of FT hood TX when they first arrived in June 1998. MOS 68Y. These cars are easy!!! and I've owned 7 of them, the first 951 in year 2000. I'm running 7.53 CR and high boost on this build. If anyone want to follow then by all means I will help answer any questions to my build. And after this I'm building my 2.7L 8v turbo for my daily driver. But first things first. If anyone wants to help they can offer me parts at a cheaper price!
Thank you for your service. I'm a veteran, NROTC, never saw wartime efforts of our current soldiers, but know their plight as a Wounded Warrior volunteer at my place in Greer. www.antlerridge.com
Our local MEN take these veteran's fly fishing, four wheeling, etc. in honor of their service.
With that shared, we all need help at times. This list is part of that place in service. Trust me, I'm in constant need of TEAM - HELP being present towards all I serve, and those I'm paying for same.
Lol you think it is still 6.5:1 CR? I have built 911 engines for several years and trust me, there is just crank and engine case that remain stock (and heads, though modified) at these power levels. Usually 8.5:1 CR is chosen and twin plug that is essential for such kind of build. Right now I am kind of involved in 964 build that consists of 4.0 crank, xtreme heads, Pankl titanium rods, custom JE pistons and VEMS twin plug COP (12x) from me, aim is 1200+ rwhp.
911 does not use headgaskets. Please make some more research about 911 engines before making such noob comments. 8.5:1 with twin plug air cooled engine is perfectly good, proven times and times again.
When you have built few 911 engines that do not blow up (I have), then we can talk about it further
Just for the reference, my car runs again and stronger than ever..
Ok so new PSI goal after looking at that graph is 20 psi. Thanks Voith for posting that. I was told by Mike Lindsey a few months back to not go below 7.5:1 CR. on these engines, got lucky and hit that number almost right on. He also said the lowest CR engine will produce more high end power under boost. The trade off is the turbo lag.
Ok so new PSI goal after looking at that graph is 20 psi. Thanks Voith for posting that. I was told by Mike Lindsey a few months back to not go below 7.5:1 CR. on these engines, got lucky and hit that number almost right on. He also said the lowest CR engine will produce more high end power under boost. The trade off is the turbo lag.
If you've got e85, say screw it and run 29psi/2bar boost and see if you can blow the 928 head off lol
I seen better fuel mileage with premium gasoline over e85. Less pit stops for fueling. And e85 isn't everywhere around where I live. Good idea. Might even blow the intake and exhaust off. I'm not stopping you from running with that idea yourself.
Of course not. These are earings you get free with gasket set.
Lol.
Just shows that you know nothing about these engines. These are just for the oil not to drip. Sealing for combustion is done purely by head/cylinder contact.
Wow, you should be the worlds smartest porsche mechanic ever. Strange porsche doesn't kidnap you while you sleep.
lol
You built few 911 engines, most impressive. Can I paypal you for a beer?
lol
I know a mechanic that lives near me and passed 1500 built porsche motosrport engines some 3 years ago, including several 959 dakar engines and he is only 5% as smart as you are.
lol
But he did built some powerful air cooled engines and in each one he used head gaskets or whatever you want to call rings between head and cylinder.
You guys a 911 have nothing to do with a 928 4V head build on the 951. Not even the same car, just have the same manufacture badge. In fact the 944/951 is more an Audi then a Porsche. The 968 however was built at a Porsche plant unlike the 944/951 (built at the Audi plant)so it's more a Porsche. If you want to argue 911 stuff go to that forum please. I only know 944/951 stuff (very little 968) and that's as much as I can afford a Porsche. If you can provide good information like you have and other have also on these cars then by all means show what you got or have done. But let's stick to the 944 series car talk here please. Good talk and thank you.
08-28-2015, 10:31 AM
I have built 911 engines for several years and trust me, there is just crank and engine case that remain stock (and heads, though modified) at these power levels. Usually 8.5:1 CR is chosen and twin plug that is essential for such kind of build. Right now I am kind of involved in 964 build that consists of 4.0 crank, xtreme heads, Pankl titanium rods, custom JE pistons and VEMS twin plug COP (12x) from me, aim is 1200+ rwhp.
