87951CJN

I was thinking about starting a 3.0 turbo conversion since my present 2.5 engine has 189,000+ miles on it. Any benefits or negatives to taking this plunge?

Many thanks,

Sam Lin

Positives - everything

Negatives - cost

Sam

87951CJN

Also does the 968 3.0 block work for this?

Sam Lin

That's required for a 3L block build, as is a 3L crank and pistons (just those 2 cost over $2500!)

Sam

BoostGuy951

Yes. Other options are blocks from any 944 S2, and any 1989 944 Non Turbo. All these blocks have the 104 mm bore. For 3 Liters you will need a crank from a 968 or a 944 S2. You can use any of those blocks with the stock crank for a 2.7 liter engine. You can bore it out to 2.8 liters pretty easily. I have never seen it done but you might reach 2.9 liters with just a bore.

Pauerman

I've been gradually traveling down this road.

About a year ago, I picked up a 968 short block that cost me $2800. In this time, piston options have increased. Andial in CA. is now selling the appropriate 104mm 968 turbo RS pistons for use with the stock length 968 rod. I believe Andial told me that the compression ratio is 8 or 8.25:1 and that the pistons are obviously intended for a 2V head.

The price on a set of these pistons is $1200 which includes wrist pins and rings.

Rods are another thing to consider. I've heard some good things about the stock 968 (forged) rods. I have been told Dwayne at Vision and by David at Powerhaus that the rods are capable of handling a reasonable amount of power (1 bar) but for peace of mind, stepping up to Carillo rods would be best if funds are available - another $900-1000

Then you gotta decide what head you want to use - modified 951 head or 2.7 n/a head. The latter would be the best option because the combustion chamber is smaller - increasing overall compression ratio with the 8:1 pistons. Also, since there is no ceramic lining in the exh. ports, this head has more potential for increased CFM's if you decide on porting.

Anyway, hope this gives you some direction. I am anticipating a total cost of $7-8 grand less the turbo.

And then there's the turbo.... but that's another story

Ahmet

Why not retain the 968 head (perhaps w/different valves, and if you want even ceramic coating on the exhaust ports), and go with a custom exhaust manifold?
Ahmet

Pauerman

Ahmet,

Sticking with the 16V head would require a custom intake manifold - big bucks. I think Powerhaus wants something like 3 grand just for the intake. Machining the 16V pistons and buying the shorter rods is another $1600 bucks.

Sticking with the 2V head is a more cost effective way to build a 3.0 and I think it is more streetable in terms of earlier torque delivery.

Vic

87951CJN

Thanks for all the info all. Pauerman I saw that you got the 968 short block for $2800, it looks like I may have an opportunity to get a brand new bare 968 block for $2500+ shipping. Does this sound like a decent deal?

Thanks,

Ahmet

Pauerman, fair enough but I was thinking if you had the turbocharger on the exhaust side, you could use the factory intake manifold. Even if the turbocharger was mounted on the intake side, I still think doing custom work to the intake manifold would be a good idea, as I feel like that's a very nice 16v to not have, especially when working w/3liters of displacement.
Ahmet

RajDatta

PH is no longer the only one who can provide you with a custom intake manifold. I had one built by SFR. David Chen can also build you one as well. All you need to provide him is a 968 intake manifold and a 944 turbo intake manifold and he can mate the 2 together. I had one built for a similar conversion and as usual, the work is very nice. Total cost will be under $1000 if you can get the 968 manifold for a good price (cheap plug, I have one ).
I have the 2.7 NA head setup with dished pistons and shorter rods and this engine makes gobs of torque and pulls very very strong. The best part is that you can pretty much use most 944 turbo parts if you go with a 2.7 head. All you have to do is port match your intake manifold to the oval ports on your 2.7 head.
I am ehlping a friend with a custom 16 valve conversion with the same shortblock. So far from what I have learned, 944 S2 head can be a better setup as no variocam issues with it. Also, the smaller intake ports of an S2 head make it more suitable for torque while the 968 head has better flow charateristics at high rpm. In either case, it will be almost impossible to do it all for under $15k, give or take a few.

Pauerman

If you consider all the parts you still need to fill your bare block ie. crank, rods (if you wanted stock rods), and misc parts, you'll probably end up at the $4000 mark for just your short block

969TurboS you have a PM

John Anderson

We are currently building a 2.7 liter turbo from the factory 2.7 block. We are usiing the 2.7 head, and stock pistons. The pistons have been shaved to allow a lower compression of 9:1. A 2.5 liter crank is still the customers choice (price). The rods are 951 forged rods that have been carefully balnced and matched. We had to tap the upper balance shaft cover for the stock oil feed to the turbo. The oil pan already has the provision for the drain. The 951 intake (like mentioned above) will be poart matched to fit the larger/ oval intake ports on the 2.7 liter head. Other than that, 951 parts all the way back, exhaust manifolds, throttle body, crossover, very simple...just a ton of labor and a little machining. We will tune it to run 11-12 psi boost. The turbo is a hopped up K26 with a #8 hotside. Fuel will be tuned in using adjustable fuel pressure regulator and an MAF kit with the Split Second ARCII fuel controller. THe motor is going into an 88 NA and is a local auto crosser. Should be fun, and quick to spool.

If anyone has any questions on conversions feel free to ask, we have done a lot of them ranging in all engine sizes on the 944.

Take Care

Matt H

John - in the mid part of next year I am planning on going to 2.7, 2.8 or 3.0 conversion on my 951. Is there any particular benefit of one to the other. Does the price change drastically with each step? My goal is a little over 400RWHP and to run about 15-17 psi while driving the car daily (mostly).
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John Anderson

Hi Matt,

First pricing, there are a ton of variables when going this far with an engine. For instance, the motor we are installing (2.7 stock engine) came to me for a very small price and it was in excellent condition. Had I believe only 40k on the motor. The customer wanted a 2.8 liter turbo conversion. We agreed that there is very little difference in the bored and sleeved engine (size is actually a 2.7 somthing rounded up) and for this exchange, it was a lot cheaper to use the stock 2.7 block.

Keep in mind also that our goal is a quick spooling 300 ish hp motor for street and autocross. For your goal, look at the combination of hardwar you would need to get a dependable 400 to the wheels at a modest boost level.

You can start with a 2.7+/-, block and get those numbers, but 15-17 psi boost will require other parts to achieve the goal, mainly looking at engine management to get your timing dialed in. On my old 951 I went with the bored 2.7ish block and dynoed at 420Hp/520tq at the rears but at 18-19 psi boost setting on the lectric boost controller. BUT, I was using the tried and true MAF kit with split second ARCII unit. Now, had I spent an additional 3000+ on stand alone and dyno tuning I might have reached the same numbers at a much less boost level. so, although the block and related engine equipment might only be so much money, your looking at higher ad on costs. So maybe spending an extra 2000 buying a spun 3.0 liter engine will actually be cheaper for your goal than using a pumped up small block? I know this is rough, but at least it will get you thinking on it :-)

As far as numbers, yes you can get those on a 2.5, 2.7ish, 3.0 but I think going to the bigger block and using simple equipment is most likely your cheapest way to go.

Take Care