Kool

I know that it has been done. How involved do you guys think that it would be to build a turbo charged motor. Would you have to use a stand alone or could you use a KLR and DME out of a 951 and change the mapping. What would have to be done to the internals besides lower compression pistons. Anybody want to comment please do.

Ski

Don't know all the details but you can contact these people as they have done it,,others too probably:

<a href="http://www.visionmotorsports.com" target="_blank">www.visionmotorsports.com</a>

<a href="http://www.powerhaus.com" target="_blank">www.powerhaus.com</a>

Have your checkbook ready...I think Vision kept the Variocam on the 968 motor and Powerhaus did away with it, not quite sure. Ask for Rob or Dwain at Vision and David at Powerhaus.

Kool

I saw the price of the motor that Powerhaus has that is a lot of money. I just wonder how much is involved.

Tom Pultz

There are various ways to go about this depending on whether you plan to use the 16V head or you want to emulate the factory 968 Turbo S using an 8V design. The factory used a unique 8V head that was more or less a combination of 2.7 liter design (which bolts to the 3 liter block), but with the valve stem diameters of the 16V head so they could fit in a larger water jacket.

Using the 16V head may be fine for street use but it was never designed for the cooling required in a turbo charged engine.

Another option might be a low pressure turbo installation using stock compression ratio. I believe Scott Gomes at Under Pressure Performance has done this. I don't believe he posts to these forums, but he's on the 944 and 951 mailing lists.

And of course there's the Huntley Racing supercharger kits you might consider.

Sloth

Albert Broadfoot at <a href="http://www.broadfoot-racing.com" target="_blank">Broadfoot Racing</a> has built a turbo charged 3L race engine for us before. I know that he is currently working on a 3.2L turbo. Give them a call as I am sure that he could help you out.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Danno

Get the Oct. issue of European Car where they featured Kelly's 951 powered by a 968 turbocharged engine. It got 500hp from 1.2bar or so of boost. Gave some cursory coverage of the mods needed. That's a good deal for less than $20. The PowerHaus 968 turbo conversion costs something like $25k for 350hp.

Remember that this is extending Porsche's own development work since they never built a 16v 968 turbo engine. So you gotta do a LOT of extra steps. Things like stronger con-rods and perhaps even pistons. Ceramic-coat the heads and get stainless and/or sodium-filled valves. Aftermarket EFI is really the only way to tune such a beast effectively.

Luke

why not start with a S2 motor and not have to do away with the vario cam. THat eventually will be my goal.

Besides, that add that powrehaus runs EVERY Excellence issue quotes $5k for turbo charged S2 conversions

Tom Pultz

Luke you have seriously fallen behind Danno in the posting dept. today... get with the program... or <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> Geez, just since I posted this you have caught up a bit

Luke

phhhhh what eva MR. 396

Danno

Actually there's nothing wrong with the VarioCam. It will help provide you with a torque/HP boost above 5500rpm where modified Turbos have a tremendous torque drop-off. Sure you can retard the cam permanently with an adjustable sprocket, but then you still have the same narrow powerband, just higher up. The VarioCam will give you both low-end torque and high-end HP.

But primary problem with the 16v heads is in the cam-chain tensioner pads. The single-shear mounting post is also a bad design, but at least it breaks off, and perhaps may save the chain from breaking and messing up BOTH your cams AND your valves.

I don't like the cam chain design at all. It would've been so much better if they just used individual sprockets for each cam (like ALL other DOHC engines out there). Then they can implement VarioCam mechanism with a hydraulic helical coil between the sprocket and camshaft like BMW's double-VANOS or Toyota's VVTi (which are continously variable, way better than VarioCam or Honda's VTEC).

I still think the best variable-valve scheme is Ferrari's 3-D cam-lobe used on the F355's 5-valve heads!

CBass

There are several ways to build a 968 Turbo motor.

To build a 500 hp, 450 ftlb motor, you will need to change:

connecting rods-----------------------$2000
intake--------------------------------$50-$4000
exhaust-------------------------------$200-$1000
turbo + IC----------------------------$1500-$3000
stud kit------------------------------$500
chip----------------------------------$500

You can modify the intake manifold, modify a 951 manifold to fit, or get a really expensive barrel valve intake(nice)

You can buy the exhaust, fabricate it, or have a shop custom build it for you.

The turbo can be bought from a number of places. Kokeln, Turbonetics, Ebay... and so on. You could even use a used turbo, but I wouldn't advise it.

You have to rebuild the bottom end of the motor, with new rods. The rods drop the compression to 8:1 with stock pistons.

You need a stud kit to keep the motor together.

You need a custom chip for the turbo, but you still use the stock Motronic system.

You will need to upgrade to bigger injectors.. may want to consider MAF, or a stand alone...

Danno

"You need a custom chip for the turbo, but you still use the stock Motronic system."

Huh? Has anyone turbocharged a 968 while retaining the stock 968 DME?

Kool

what about a waste gate and a cotroller?

CarreraCup03

According to Dwain at Vision, You can use 968 or s2 block with either 2.5 turbo or 2.7 NA head, stock 968 pistons (forged unlike s2), shorter custon com rods ... to lower the compression, shorter head studs (if using 2.5l head), and widefire 3L head gasket. Now this assumes you have larger injectors, wastgate, turbo, chips, and some sort of boost control. Dwain will only tune these cars with 1 bar of boost ... so he does not put on a boost controler. He also does not reccomend an maf, and says the stock airbox can be tuned for this application.

I have an MAF and will be using it for this application.

With the stock 968 pistons, and the shorter rod ... the comp ratio according to Dwain is 9.5. This seems high by turbo standards, but Dwian says with low boost (1 bar!) it is completely safe and reliable.

I am giving it a try ... will let you know how it turns out.

944turbo

Kool

I am assuming that if you are using the 2.5l Turbo head that you are also going to have to use the intake manifold from the 2.5 Is that correct.

How much HP do you expect from the set up?