Porsche 944 turbo road to racecar.

[Gammaboy]

The cylinder head just turns around, it is the same casting as S4 928

Smart idea to turn it around,

Er, wouldn't you just use the other 928 head rather than flipping it round?

[clutch-monkey]

The cylinder head just turns around, it is the same casting as S4 928

Smart idea to turn it around, but if I were doing that I'm not sure I'd run such a long set of headers, but that is just me.....

John Kuhn, Kuhn Performance, has just cast up a beautifull set of turbo exhaust manifolds for his twin turbo kits, that is what I'd be using.

So.. On a 928, could make it so you can mount turbo in the valley of the v8? Interdasting

[Roy928tt]

Yes, you could, It did cross my mind.....

[333pg333]

It is now also becoming apparent that there may be some inefficient cooling to the head. From what I've seen, some extra venting to increase water flow around head might be the trick. Also moving or removing thermostat could be another option. Fast running out of energy and funds to continue dealing with this thing though....

[333pg333]

Pic as at 5pm tonight. Ready to go to Dyno tomorrow after putting motor together twice in last week. At 6pm we have decided to cancel that and pull motor down yet again to modify the deckplate for further cooling of the head via more water passages which were blocked off compared to last motor. We think the head has just overheated and no matter how strong the studs and serts are, it will remain a problem until we fix it. Fuck fuck fucketty....

[Roy928tt]

What was the thinking with not having all of the cooling holes open ?

[dougmo]

can you add an external cooling manifold to get some hot water out of the top of the head?
only needs to be simple

[333pg333]

What was the thinking with not having all of the cooling holes open ?

The deckplated block was already built. It was sent to us and we just used it. Didn't notice that the water passages were somewhat different. Kind of a silly oversight really, but that's what you get when you're always playing catchup...or not playing with it at all.

can you add an external cooling manifold to get some hot water out of the top of the head?
only needs to be simple

You're right George and yes it can be done quite simply. Going to look at this too.

[da9jeff]

Should look at dry decking ie no water through the head gasket. That with an o-ringed block would be the go.

[CT]

It is now also becoming apparent that there may be some inefficient cooling to the head. From what I've seen, some extra venting to increase water flow around head might be the trick. Also moving or removing thermostat could be another option. Fast running out of energy and funds to continue dealing with this thing though....

One of the things that really worked on the hipo turbo MX5s were reversing the waterflow and using a sealed radiator. We used en electric pump, with an external water pipe about 32mm diameter that ran above the height of the water jackets in the head to redirect the flow with two steam ports which were plumbed to a plastic overflow bottle with a 25psi cap. The radiator also had a steam port plumbed to the overflow bottle - was off a mazda 3 from memory. We also ran a factory thermostat but stuck it at the back of the head using an escort housing which required only minor mods to bolt up. This allowed my old car to run at full noise on 40c plus days (oh Oran Park I miss you) without ever having overheating or head issues. Took a few years to work this out though.

[Roy928tt]

Damned if I know if it is of any use to anybody, but, the bore spacing on the 928, 944 block is the same as Big Block Chev !!

Yes apparently it is possible to build a 32 valve quad cam BBC using 928 heads....

[333pg333]

Feeling a little more confident that we definitely did the right thing. As you can see in the before and after shots, it's quite clear that this should make a lot of difference. Kicking myself that I didn't really think of this until now.
Going to move the T-stat onto the radiator like the Supertaxis. Along with the more stable studs we're hopeful that it will take more boost without lifting the head. Seriously thinking about going from the GTX35 to a GTX3076 also. Not quite sure what sort of hp you can max out of them but it should help response.

[Cal]

One of the things that really worked on the hipo turbo MX5s were reversing the waterflow and using a sealed radiator. We used en electric pump, with an external water pipe about 32mm diameter that ran above the height of the water jackets in the head to redirect the flow with two steam ports which were plumbed to a plastic overflow bottle with a 25psi cap. The radiator also had a steam port plumbed to the overflow bottle - was off a mazda 3 from memory. We also ran a factory thermostat but stuck it at the back of the head using an escort housing which required only minor mods to bolt up. This allowed my old car to run at full noise on 40c plus days (oh Oran Park I miss you) without ever having overheating or head issues. Took a few years to work this out though.

Wasn't reversing the water flow just to bring it back to what it should always have been because the BP was designed to be fitted to FWD cars and the MX5 was the first time it had been fitted longitudinally?

[CT]

Hey Cal, it was a couple of things, the flow as you say and the angle of the engine meant it got hot spots around cylinders 3/4 too so reversing the flow seemed to fix that as well. That and increasing the system pressure and capacity.

[333pg333]

We've also changed the stock T-stat setup and removed it. The stock T-stat is slow to react and could have worsened the cooling in such a car. We've blocked off the water jacket in the head and put a billet T-stat setup from a SuperTaxi. Pretty basic but effective. Modded the radiator with a baffle so that the top four rows work all the time and when the T-Stat opens it bypasses the baffle and the whole rad works. So there's always flow going on.