Tom M'Guinn

Would it work to build a 3 liter turbo out of a 968 motor by:

1. Replacing the pistons with the new Mahle 3 liter turbo pistons

2. Using a 2.7 N/A head, modified to port match the intake manifold, and to modify the water passage to match the 3 liter block (hi-tech exhaust valves needed?)

If so, would this set up drop in to a 951 with stock exhaust and turbo plumbing without hassles?

What flywheel/clutch/starter is needed to install with a stock 951 power train?

Does the 86 style timing belt tensioner/waterpump set up work with this combination, or is something else needed?

Does the stock turbo cam work with the 2.7 head?

Do all 951 accessories bolt to the 3 liter block (alternator, power steering, a/c, motor mounts, etc.)

fast951

- 951 exhaust valves can be used, also the valve springs must be changed.
- The 3.0L block has the late style (post 86) tensioners.
- 951 Waterpump may not work with a 3.0L block.
- All other 951 parts should work.

- Balance shaft cover needs to be modified for turbo oil feed line.
- 951 Engine mount (left one for turbo), and oil pan to be used.

Selecting the proper turbo and the tuning where things get to be interesting...

BoostGuy951

You may need to Replace the Rods with a strong aftermarket unit.

Matt Sheppard

I understand a rod change may be appropriate too - stock length, but forged. It's also an opportunity to drop some recip. weight by using say a Pauter rod. The foged 951 rod should be just fine and groovy too, but I'd work them over (shot peen, resize/rebush, balance both ends) and use aftermarket bolts/nuts - ARP's are nice. At that point, you might be better off just buying a Pauter rod set for the money. On my rebuild that I'm ready to put in my '87 car, I used '83 944 rods (forged) and was able to take 10 grams off each rod by smoothing the sharp edges and cutting down the balance pads - kinda not worth the effort, really, but I had the time. Design wise, I think the '83 forged rod is superior to the turbo rod, but that's just from observing the two side by side. Their weights were virtually identical between the 2 designs. The turbo rod looked like it had more opportunity to shave weight and had much sharper shape transitions. Here is a pic of the rods next to each other, the bottom is the 951 rod.




Also as for the dogma that only '86 turbo rods were forged, I've yet to see any turbo engine that upon tear-down had anything but the forged rod in it (?) . . . personally witnessed '86, and '87 engines and seen pics of stock 88 and 89 disassemblies, all had the telltale "square" rods.

I have read on the board that some M.Y. 968 rods were cast and later M.Y. rods were forged . . . I would NOT trust a cast rod in any HP engine. Based on a previous board discussion, I'd prob. not reuse ANY 968 rod. Here is a pic from that thread with the 968 rod (bent) and a turbo rod in the middle.

Ahmet

It is my understanding that the forging method used for the early 944s is similar to the 87&up turbo rods, ie sintered. The 86 turbos had fully forged rods, making them the strongest of the bunch. BTW, I've seen an 86 turbo that broke a piston, and besides that the bottom end was fine.
Ahmet

Songzzz

I am buying parts for my 3.0L project too.

Can the 86-951's forged rods be used on a 3.0L turbo?

Hmm, thinking of saving me some money.

RajDatta

Yes I have one in my car that has been reliable for the last 7 yrs.

Quote:

1. Replacing the pistons with the new Mahle 3 liter turbo pistons

Yes, this has taken the guess work out of dishing/shaving pistons and at $1280 or so, is a fair price. I would swap for 87.8mm carillo rods though.

Quote:

2. Using a 2.7 N/A head, modified to port match the intake manifold, and to modify the water passage to match the 3 liter block (hi-tech exhaust valves needed?)

No need to modify the head, its the intake manifold that needs to be modified to port match the oval ports of the 2.7 NA head. No need to modify the water passages. That is the reason to use a 2.7 NA head as it has the same same water jackets with the same 104mm bore. You only need to modify the water jackets if you want to use a 944 turbo head which atleast visually does not look very pretty. Swap the exhaust valves to 944 turbo sodium filled ones, swap the valve springs and you are good to go.

Quote:

If so, would this set up drop in to a 951 with stock exhaust and turbo plumbing without hassles?

Yes, no hassles form that point on. Keep your 944 turbo flywheel, housing and torque tube setup and everything will be fine. Ofcourse you will need to run 944 turbo electronics.

Quote:

What flywheel/clutch/starter is needed to install with a stock 951 power train?

Same as what you have in your 944 turbo. You can upgrade to beefier units for added power.
In my case, the 968 housing was modified to clear the wastegate and a custom billet flywheel was used with the 968 torque tube but this is not required.

Quote:

Does the 86 style timing belt tensioner/waterpump set up work with this combination, or is something else needed?

No, change to the 968 water pump. As far as tensioner, DO NOT use a 968 tensioner. Use an S2 or a later style spring loaded 944 turbo/S2 tensioner. It is a direct bolton. You will need to swap to turbo style belt covers and ofcourse your timing belt will be 944 turbo.

Quote:

Does the stock turbo cam work with the 2.7 head?

Yes, that is what I currently run and it works very well and is a direct bolt-on as well. Don't forget to order 89 NA intake manifold gaskets, the rest of the gaskets are 944 turbo.

Quote:

Do all 951 accessories bolt to the 3 liter block (alternator, power steering, a/c, motor mounts, etc.)

Everything else is a bolton except you will need to tap into your balance shaft housing for the oil feed to the turbo. You will also need to swap the turbo/engine mount and tap the oil pan for the oil return line ala 944 turbo.
Trust me, to tune it is not rocket science. I am currently running a APE MAF setup with a K27/8 and it works very well. You can either run stock injectors upto 320rwhp (maxing them out) or go to bigger injectors and get a piggy back of some kind to fine tune the bigger injectors.
I have 2 sets of chips for this setup. Let me know if I can be of any help. I just pulled on a 3.6 turbo that was running 1 bar and custom exhaust. I am running similar boost and was pulling on him. I thought that was pretty impressive for a car that is used as a daily driver sometimes.

RajDatta

Songzzz, those rods are way too short. Why are you trying to reinvent the wheel? lol

Songzzz

raj,,,, i tot this thread was meant for idiots.

RajDatta

Hahaha, too funny!

Songzzz

raj, i changed my mind about going the 8V route. Since i have a good source for japanese engine management system here in the far east, 16V head seems to be the better option.

According to Powerhaus, their 16V turbo made 100ftlbs more torque.....

Recently, I was talking to a friend (an Electronics Engineer - DSP expert). He did an atopsy on my Power Perfect(951) and the Authronic EMS, then laughed his head off when he found out about the $$$. HE claims that we could easily make/or copy one for a fraction of the cost.

hmmm, maybe...

Sam Lin

Songzzz, that's definitely true, especially with manufacturing in the Far East - I've thought about similar things, not only with electronics but with production stuff like replacement lower control arms, etc - setup/tooling/mold fees would be so easy to recoup on those to bring out a far cheaper product

Sam

Songzzz

Sam, Right. I custom made my 951 intercooler in Taiwan for only about USD 200!!!

I have the connections with several the good factories over here that can easily come out with those stuff you mentioned. Before going into such OEM business, the crucial factor would be the "quantity".

If you are seriously looking into doing it, send me a PM, we can work out something.

Anyone knows where Motech manufacture their stuff?

Duke

Now THAT sounds interesting!!

RajDatta

Songzzz, Motec is an Aussie company.
Ask David, how does the torque peak compare between a 16 valve and an 8 valve head. If you want an all out racer that is more high strung, 16 valves is the way to go. It will require additional custom exhaust and intake. Also, you will need to figure out which head to use.
If you want a fast car that is a pleasure to drive around town and has gobs of low end torque, 8 valve is the route. Like I said earlier in another post, I was able to pull on a 3.6 turbo