white924s

I don't think that the 2.5l 8v block will work with the 944S head. I looked into this, and from what I could find reading online and studying pictures of the head gaskets, the water passages won't line up correctly for the 944S head. You would need 944S pistons, true, but that's not a bad thing because 944S had a higher static CR than the 8v engine.

I haven't tried to do it, so I could be wrong, but that's what I found looking around here and on other sites. If you or someone else has built a frankenstein motor like that (2.5l block from an 8v and a 16v head), I would love to be proven wrong on this.

I believe that the 2.7L head bolts up to the S2 and 968 blocks because it has a different water passage profile. Indeed, one of the services that Lindsey Racing offers on their site for cylinder head work is water passage modification for the 3.0L block

V2Rocket

944 8v and 944S blocks are basically the same.

the blocks that dont line up are the 104mm blocks, those in the 2.7 and 3.0 cars. the water passages are different.

white924s

the blocks may be very similar externally, but I do believe that the water passages are slightly different. Take a look at these 2 pictures from 944Online (hope they don't mind me borrowing them!)

944S:



944 8v:



The differences are subtle but it does look from these pictures like it wouldn't quite line up. You could probably do a little machining to match the water passages, but at that point, you're probably better off just getting a full 944S motor. They're not as expensive as S2 or 968 engines, and the 944S block would bolt right in to an 8v engine bay (engine management might not be 100% straightforward)

Olli Snellman

Just turn that 944S pictute upside down, then evrything match just fine. 944S uses the same block as 8V 944. 2,7L 8V block is the same as 944 S2 16V block is.

What comes to get power from 2,5L 8V i have an example. One fellow i know drives a 944 8V in local endurance series. Car is a early eurospec with 163hp (higher compression) to start with. So far the mods are:

new chip
adjustable cam gear
modified head channels
modified exhaust

They have dynoed it 177hp, so they got 14 additional hp. Class rules demand using orignal motronic, with some other system some extra hp my be achived.
To get even more i suppose best way to get it is to have new cam & itb's. Most likely they will give 10-15hp.

V2Rocket

white924s

call me crazy, but even upside down the ports at the top still don't look the same...the 16v passages look more square. Are you sure they would work?

As I said before, I didn't go through with trying this, so I don't know for sure, but if someone actually did turn an 8v into a 16v 2.5l engine, I'd be interested to know more, just out of curiousity.

For my own car, I already have a fair bit invested in keeping the 8v head - I have a MSDS header and LR exhaust. What I'm thinking about now is having Lindsey Racing machine my head to work with a 2.7l engine and getting 89 944S pistons, injectors, fuel regulator and DME. My goal will be more hp than the 2.5l but maintaining factory-like reliability and drivability

krystar

yea it looks like the ports are in the same spots. matches one port to one port. but the shapes don't match up. although that's nothing that can't be reworked if necessary....

Olli Snellman

S Head will work directly with 8V block. It has been done, by Porsche and by some others. Why on earth Porsche would make just-for-944S-block when they had 8V block available. Same thing with 1989 2,7L engines. Factory reduce cost and use one block for 8V & 16V engines. They just made few changes to 8V head design to accept 104mm S2 block. Then they just added a 2,5L crank with new pistons.

So if i understood correctly your parts bin contains now 2,7L engine, why would you like to use S pistons? They are designed for 16V head. What head are you going to use? If you have a 2,7L engine it is more or less a S2 104mm block with 2,5 L crank. Just get a 1989 2,7L head, it will bolt on directly to your block. With 2,5L head you will have to change water passage on front left corner, not any rocket sciense, but easier to do with proper head. 2,7L head ports are also much nicer compared to 2,5L ones. Here's few pictures i took from my project engines, you can easily see the differences:

2,5L head:




2,7L head:



2,5L block:



2,7/3,0L block:

white924s

sorry, that was a typo on my part - I meant to say 89 944 8v pistons....the 10.9:1 CR, 2.7L pistons, not 944S pistons, which as you said are smaler bore and for a 16v head

I haven't actually started yet, I'm still in the planning phase - trying to see how much it will cost relative to a straight rebuild. My only reason to shy away from getting a 2.7l block and head is that the 2.7l head costs a lot. I figure for the same money, Lindsey Racing will do a stage 2 head rebuild w/ water port modification that will flow about the same amount of air (if not more). But if a 2.7l head came along for the right price I would snap it up

whalebird

Cool project. I will be doing this soon to my 924S. I am researching the same options being discussed here. Keep up the good work guys. It shouldn't take a lot to make a fast 924S as light as they are and the gear ratios.

Olli Snellman

S2 blocks can be found (here in europe) between 500-800€ depending the condition. I bought some time ago 4 factory new unused 2,7L heads 700€ each. two of them are already used for 3.0L 951 projects and two of them i have reserved for my future projects.

white924s

wow...at current exchange rates, those factory heads are a steal - any chance there are any more where they came from? In the US, used 2.7l heads seem to go for a little more than that, and I don't know what an unused one would fetch. The other reason I'd prefer to keep and modify my 2.5l head is I don't want to have to also replace my intake manifold - the 2.7 ports are slightly different. I suppose an alternative would be to just port my current manifold

smokin_944

I'm not so sure. One of the guys at Eurocars (exotic car shop in Winnipeg) has an 84 944 with a turbo S rig transplanted into it. It puts out over 400 rwhp on dyno. It is outrageously fast in a straight line! And it isn't even sleeved like my project engine.

V2Rocket

turbo engines are a different story altogether.

for $1700 you can get bolt-on parts to get your 951 to 300WHP, which is about what youd pay for the custom pistons and rods and machine work to get your NA to 165HP

OFFdutyHERO

Not stirring the pot but there is a kid near where I live that has an 85.5 that used a factory saab 900 turbo and runs something like 6-7 psi...maybe less not sure...but he has to make about 200 and that car is awesome quick! Its what made me buy my 944's.

food for thought....