09-21-2008, 08:05 AM
I was unable to start this post in the 'modifications' section, so I started it here. Feel free to move it where ever it sould go.
After 7 months of deep contemplation and 'the need for more speed,' I feel that I must go forward with a 968 turbo conversion. The basic idea is to up the torque and horsepower to a range that is satisfying, somewhat effecient, and can easily be tolerated by the engine. This includes a new exhaust system, new cooling system, new intake system, new fuel management system, and engine internal modifications. What I want is mid to high rpm (3.5-7) turbo on.
There are several ways to approach these needs. I would like to make this as cost effective as possible (read: least expensive..BUT quality work) I emailed and called several vendors and no one really wanted to receive my car, pull the engine, do the work, and send it back to me at anything close to a reasonable rate (one quote was 35g's).
Since I happen to have a spare Garrett turbo of what I think is close to the right intake/exhaust housing size, and a really nice racing wastegate from a prior project, I decided to start the project. I will probably have to do some turbine/compressor wheel work for the best match. See pics.
I was able to secure coated 951 crossover pipe and turbo down pipe for a very reasonable rate. Complete turbo exhaust systems can be had for under 1000$, downpipe flange to the tip with the cat!
I will have to cut and weld the flanges to align with the 968 exhaust manifold. For engine management, I decided to go with Haltech Ev11. It allows sequential injection and control of everything.
http://www.haltech.com/e11v2.htm
Engine internals: I think the nikisil coated cylinders will handle the added boost just fine to a certain point. I don;t plan on any extreme loads, just something in the 350-400 crank hp range. There are several options:
1) Mahle 968 turbo pistons (30cc dish 104mm bore )and 968 crank
2) Mahle standard size pistons and lower compression with 944 crank
3) combo turbo pistons and 944 crank
4) no internal change and run low boost
5) my old pistons and 944 crank
I think the best choice is 944 crank and mahle standard size pistons which decreases the CR and allows slightly higher revs. Standard 944 crank decreases piston height ~4.5mm and decreses rotating mass and other stresses. Now how about valve overlap with the variocam??? Well, that is one major obstacle. I can control the vario actuator with the haltech. I just have to find out if it is an all or nothing action or the timing is 'truely' variable by increments and what those are. Maybe I will just unhook the plug.....I have very successfully used mild race cams with overlap on turbo engines before, and the high end has been superb.
Intake: Second difficult part is configuring the new intake manifold. Obviously no room for turbo and 5th runner. Luckily, there is this:
http://www.powerhaus.com/
these guys can make a real pretty intake! Since haltech controls all functions, no need for air mass sensor!! just intercooler and tubing. HMR and powerhaus both supply these.
Cooling: HMR aluminum radiator (the thinner one). probably put in a new h2o pump as well. Garrett turbo I have has oil and h20 cooling so have to plumb these...not hard at all because I will have extra line run from the throttle body! Oil will be with the 944 engine mount draining possibly through a seperate cooler then to crank case (above oil line). I have thin high flow fans form another project OR i can use stock fans with the thin alu rad from HMR.
CLUTCH: probably go with 944 torque tube and housing (to clear exhaust)and lightened higher pressure clutch and one of my 968 transaxles...all readily available.
Several other things will have to be worked out as well such as injectors (but i have a set of four high flow which will probably work) I already have the exhaust temp, boost, oil temp, oil pressure, and h20 temp gauges (autometer) Wiring the Haltech is very simple.
will of course replace engine bearings, all seals, widefire head gasket, head work etc. So, this seems like a fun project!! I do have to say Thanks to Flash for his pessemistic/reasonable side convinced me to go with 968 engine rather than 944 engine in a 968!
This whole deal will take many months and I don;t plan on pulling the engine until I have all the parts ready to go. I have to do the stealth purchases so my better half does not notice them!
here are some pics of the beginnings:
After 7 months of deep contemplation and 'the need for more speed,' I feel that I must go forward with a 968 turbo conversion. The basic idea is to up the torque and horsepower to a range that is satisfying, somewhat effecient, and can easily be tolerated by the engine. This includes a new exhaust system, new cooling system, new intake system, new fuel management system, and engine internal modifications. What I want is mid to high rpm (3.5-7) turbo on.
There are several ways to approach these needs. I would like to make this as cost effective as possible (read: least expensive..BUT quality work) I emailed and called several vendors and no one really wanted to receive my car, pull the engine, do the work, and send it back to me at anything close to a reasonable rate (one quote was 35g's).
Since I happen to have a spare Garrett turbo of what I think is close to the right intake/exhaust housing size, and a really nice racing wastegate from a prior project, I decided to start the project. I will probably have to do some turbine/compressor wheel work for the best match. See pics.
I was able to secure coated 951 crossover pipe and turbo down pipe for a very reasonable rate. Complete turbo exhaust systems can be had for under 1000$, downpipe flange to the tip with the cat!
I will have to cut and weld the flanges to align with the 968 exhaust manifold. For engine management, I decided to go with Haltech Ev11. It allows sequential injection and control of everything.
http://www.haltech.com/e11v2.htm
Engine internals: I think the nikisil coated cylinders will handle the added boost just fine to a certain point. I don;t plan on any extreme loads, just something in the 350-400 crank hp range. There are several options:
1) Mahle 968 turbo pistons (30cc dish 104mm bore )and 968 crank
2) Mahle standard size pistons and lower compression with 944 crank
3) combo turbo pistons and 944 crank
4) no internal change and run low boost
5) my old pistons and 944 crank
I think the best choice is 944 crank and mahle standard size pistons which decreases the CR and allows slightly higher revs. Standard 944 crank decreases piston height ~4.5mm and decreses rotating mass and other stresses. Now how about valve overlap with the variocam??? Well, that is one major obstacle. I can control the vario actuator with the haltech. I just have to find out if it is an all or nothing action or the timing is 'truely' variable by increments and what those are. Maybe I will just unhook the plug.....I have very successfully used mild race cams with overlap on turbo engines before, and the high end has been superb.
Intake: Second difficult part is configuring the new intake manifold. Obviously no room for turbo and 5th runner. Luckily, there is this:
http://www.powerhaus.com/
these guys can make a real pretty intake! Since haltech controls all functions, no need for air mass sensor!! just intercooler and tubing. HMR and powerhaus both supply these.
Cooling: HMR aluminum radiator (the thinner one). probably put in a new h2o pump as well. Garrett turbo I have has oil and h20 cooling so have to plumb these...not hard at all because I will have extra line run from the throttle body! Oil will be with the 944 engine mount draining possibly through a seperate cooler then to crank case (above oil line). I have thin high flow fans form another project OR i can use stock fans with the thin alu rad from HMR.
CLUTCH: probably go with 944 torque tube and housing (to clear exhaust)and lightened higher pressure clutch and one of my 968 transaxles...all readily available.
Several other things will have to be worked out as well such as injectors (but i have a set of four high flow which will probably work) I already have the exhaust temp, boost, oil temp, oil pressure, and h20 temp gauges (autometer) Wiring the Haltech is very simple.
will of course replace engine bearings, all seals, widefire head gasket, head work etc. So, this seems like a fun project!! I do have to say Thanks to Flash for his pessemistic/reasonable side convinced me to go with 968 engine rather than 944 engine in a 968!
This whole deal will take many months and I don;t plan on pulling the engine until I have all the parts ready to go. I have to do the stealth purchases so my better half does not notice them!
here are some pics of the beginnings:
(This post was last modified: 09-21-2008, 12:53 PM by xrad.)
