944T/968 how many years owned?
Discussion
Blade, I agree. The cost of tuning a 944 turbo or 968 for a significant power increase is too high relative to the alternatives & aftermarket parts support is declining as these cars age.
There will be a handful of highly skilled & motivated individuals who can work on these cars themselves to deliver great results but I see their numbers dwindling.
Most of the tuning stalwarts will be in the US where the cars are still relatively cheap & plentiful but I can't see much happening elsewhere despite a few dedicated individuals in Sweden & Australia.
There will be a handful of highly skilled & motivated individuals who can work on these cars themselves to deliver great results but I see their numbers dwindling.
Most of the tuning stalwarts will be in the US where the cars are still relatively cheap & plentiful but I can't see much happening elsewhere despite a few dedicated individuals in Sweden & Australia.
I’ve had my 2.5 944 for 4 years and my 2.7 944 I purchased this year. I use my 2.7 an occasional daily and it performs faultlessly. It seems to have developed an intermittent battery drain which I am yet to get around to diagnosing. I’d love to get it out to the ring this coming year. I find on a run it drives better than most moderns I’ve recently driven.
Big Tomm, I took my old 2.7 round the ring and returned with the same car running bigger brakes and a 968 engine.
I was faster and had more fun with the 2.7, probably says more about me than the car but it probably didnt help that I had a big spin on the return visit, somehow missing everything.
I was faster and had more fun with the 2.7, probably says more about me than the car but it probably didnt help that I had a big spin on the return visit, somehow missing everything.
james0 said:
Big Tomm, I took my old 2.7 round the ring and returned with the same car running bigger brakes and a 968 engine.
I was faster and had more fun with the 2.7, probably says more about me than the car but it probably didnt help that I had a big spin on the return visit, somehow missing everything.
Sounds like a very lucky, yet unwelcome experience! I found it very daunting last time I was there seeing some of the wreckages being unloaded as I was buying my tickets so a very lucky dodge. I was faster and had more fun with the 2.7, probably says more about me than the car but it probably didnt help that I had a big spin on the return visit, somehow missing everything.
Do you have any photos of your 2.7? What brakes did you opt for? I see there are quite a few options, all with different pros and cons. What did you go for and what swayed your decision?
I'm not aware that Baz ever made 944 liners as a production item - correct me if i'm wrong, but I think he merely experimented with them in that 3 litre he built.
The Darton wet sleeves eradicate the expansion differential with dry ductile iron sleeves & potential movement & weakness issues of any dry sleeves while providing a closed deck which locks the bores together.
Granted, Baz's alloy sleeves shouldn't have any expansion issues but when you put one tube inside another, all other things being equal it won't be as strong as a single tube with the same sidewall thickness.
The issue with Darton sleeves is it's entirely dependent on the skill of the installer & you need to use a torque plate before boring the sleeves (once installed) to put the block under the same compression/tensile forces as it experiences with the cylinder head in place.
Some people have had serious issues with Darton sleeves - mainly because the installer was inexperienced at the process. It means machining away the factory bores entirely.
The Darton wet sleeves eradicate the expansion differential with dry ductile iron sleeves & potential movement & weakness issues of any dry sleeves while providing a closed deck which locks the bores together.
Granted, Baz's alloy sleeves shouldn't have any expansion issues but when you put one tube inside another, all other things being equal it won't be as strong as a single tube with the same sidewall thickness.
The issue with Darton sleeves is it's entirely dependent on the skill of the installer & you need to use a torque plate before boring the sleeves (once installed) to put the block under the same compression/tensile forces as it experiences with the cylinder head in place.
Some people have had serious issues with Darton sleeves - mainly because the installer was inexperienced at the process. It means machining away the factory bores entirely.
Thought Sunday would be the end of my ownership.
Was starting the car, there was an almighty bang, followed by a scraping sound.
Amazingly the car started but the starter sounded horrific.
I removed the starter today terrified the ring gear would be chewed as I cant face another clutch job this soon.
Turns out the nose of the starter motor had snapped clean off leaving all kinds of terrible things to happen during cranking.
Also amazingly the ring gear is unmarked.
Was starting the car, there was an almighty bang, followed by a scraping sound.
Amazingly the car started but the starter sounded horrific.
I removed the starter today terrified the ring gear would be chewed as I cant face another clutch job this soon.
Turns out the nose of the starter motor had snapped clean off leaving all kinds of terrible things to happen during cranking.
Also amazingly the ring gear is unmarked.
Just a catch up on a few posts replies.
Yes I made the cylinders - aerospace alloy wet liners Nikasil plated and secured at the top to close the deck. The block is ready but I haven't fitted the liners yet. I chose a 2.5 block due to the additional coolant depth and dual inlet from the water pump. this is because I thought the 2.7 and 968 blocks had reduced the coolant depth too much for the power In envisaged producing and the heat it would need to remove.
The 996/7 Gen 1 blocks followed a similar shallow depth but many years later (and after I had started this project) the Gen 2 reversed the trend and moved back to a similar coolant depth to the 2.5 blocks - which seemed to support my decision back then.
The block then divides the coolant inlet with a baffle plate fitted half way up the inside of the block and machined to fit to the liner/cylinder diameters to separate the block into two coolant flow channels - so that half goes straight to the back and half to the front (instead of standard convention in which the coolant enters at the front - is controlled to flow to the back by the head gasket and then rises into the heads to flow forward again and out at the front - which results in the lower block temperature rising from cylinder 1 towards 4 and the head temperatures rising from 4 back to 1 creating a very unbalanced temperature gradient which would not suit the kind of power we intended to produce).
The baffle plate fitted half way down the block achieves this and the coolant then flows from one of the coolant inlets to cylinder 3 and 4 and up into the head and back out of the rear heater outlet and 1 to 2 conventionally out of the front - thus equalising the temperatures much better which are otherwise increasing from cylinder 1 back to 4. The idea then was for each of the 2 coolant outlets to be directed to left or tight front side pod radiators (like 996/7 and Boxster/Cayman etc) each with thermostats and leaving the centre of the front where the radiator used to sit to house a huge intercooler.
There are bigger high tensile studs to clamp down the heads (already machined for) and Wills/Cooper ring seals at the top.
I chose to modify the block to fit a 968 head to increase breathing capacity and also to allow the variocam device to be reversed so it reduces the overlap at high revs and boost pressures (not increases it as with conventional NA engines) since high boost turbos throw too much inlet air straight down the exhaust otherwise and flame out.
There are also special rods, sodium filled exhaust valves and numerous other bits and pieces (including a spare cylinder) and the intention was to build the most powerful 944 turbo controlled by an independent management system.
But is was all many years ago now and everything has moved on.
There is not much to do to fit the cylinders and build the block but a lot (too much now) for us to finish the project.
I would finish the block if anyone was interested but the parts stand in the books at cost. I think for anyone interested in such a project the cost would be impossible to match from scratch and represent fantastic value for the potential outcome but frankly it is not worth my while to replace the time I am presently spending on other projects that have more life and value in them just to finish this off at a loss - but would consider doing so below cost if a reasonable offer was forthcoming to make it worth my time doing it.
Penguin - Wet liners are always preferable especially if they are supported at the top in a machined recess (as these are like all our cylinder replacement work) and because of the extra coolant depth in the 2.5 block these are supported in three places and with ribs top and bottom - quite like the Darton cylinders (which look good quality and well thought out for wet iron liners). I stuck with alloy due to the need to extract more heat with such a high tuning goal for eventual output but with the right increased cold clearance they would have done the job as well.
The expansion differential between iron and alloy cylinders does not go away because of wet or dry fitment and iron liners require about 1 thou more cold clearance in most road powered conversions (up from around 2 to 2.5 thou by one thou) and perhaps up by 2 thou extra for a highly tuned turbo - but it only effects low powered running when the piston has not expanded so much as it will when under full power so for track work and racing it makes little difference as long as the cooling system is sufficient to compensate for slightly lower thermal conductivity with iron.
It's a real shame that the problems that emerged initially with the Boxster and 996 3.4 IMS bearings, cracked and "D" chunked cylinders and later scored bores presented too good an opportunity in volume and lifespan terms to ignore shifting attention to those projects - because I am still sure the overall strength of the 944/968 construction would have stood the power we planned to create.
Baz
Yes I made the cylinders - aerospace alloy wet liners Nikasil plated and secured at the top to close the deck. The block is ready but I haven't fitted the liners yet. I chose a 2.5 block due to the additional coolant depth and dual inlet from the water pump. this is because I thought the 2.7 and 968 blocks had reduced the coolant depth too much for the power In envisaged producing and the heat it would need to remove.
The 996/7 Gen 1 blocks followed a similar shallow depth but many years later (and after I had started this project) the Gen 2 reversed the trend and moved back to a similar coolant depth to the 2.5 blocks - which seemed to support my decision back then.
The block then divides the coolant inlet with a baffle plate fitted half way up the inside of the block and machined to fit to the liner/cylinder diameters to separate the block into two coolant flow channels - so that half goes straight to the back and half to the front (instead of standard convention in which the coolant enters at the front - is controlled to flow to the back by the head gasket and then rises into the heads to flow forward again and out at the front - which results in the lower block temperature rising from cylinder 1 towards 4 and the head temperatures rising from 4 back to 1 creating a very unbalanced temperature gradient which would not suit the kind of power we intended to produce).
The baffle plate fitted half way down the block achieves this and the coolant then flows from one of the coolant inlets to cylinder 3 and 4 and up into the head and back out of the rear heater outlet and 1 to 2 conventionally out of the front - thus equalising the temperatures much better which are otherwise increasing from cylinder 1 back to 4. The idea then was for each of the 2 coolant outlets to be directed to left or tight front side pod radiators (like 996/7 and Boxster/Cayman etc) each with thermostats and leaving the centre of the front where the radiator used to sit to house a huge intercooler.
There are bigger high tensile studs to clamp down the heads (already machined for) and Wills/Cooper ring seals at the top.
I chose to modify the block to fit a 968 head to increase breathing capacity and also to allow the variocam device to be reversed so it reduces the overlap at high revs and boost pressures (not increases it as with conventional NA engines) since high boost turbos throw too much inlet air straight down the exhaust otherwise and flame out.
There are also special rods, sodium filled exhaust valves and numerous other bits and pieces (including a spare cylinder) and the intention was to build the most powerful 944 turbo controlled by an independent management system.
But is was all many years ago now and everything has moved on.
There is not much to do to fit the cylinders and build the block but a lot (too much now) for us to finish the project.
I would finish the block if anyone was interested but the parts stand in the books at cost. I think for anyone interested in such a project the cost would be impossible to match from scratch and represent fantastic value for the potential outcome but frankly it is not worth my while to replace the time I am presently spending on other projects that have more life and value in them just to finish this off at a loss - but would consider doing so below cost if a reasonable offer was forthcoming to make it worth my time doing it.
Penguin - Wet liners are always preferable especially if they are supported at the top in a machined recess (as these are like all our cylinder replacement work) and because of the extra coolant depth in the 2.5 block these are supported in three places and with ribs top and bottom - quite like the Darton cylinders (which look good quality and well thought out for wet iron liners). I stuck with alloy due to the need to extract more heat with such a high tuning goal for eventual output but with the right increased cold clearance they would have done the job as well.
The expansion differential between iron and alloy cylinders does not go away because of wet or dry fitment and iron liners require about 1 thou more cold clearance in most road powered conversions (up from around 2 to 2.5 thou by one thou) and perhaps up by 2 thou extra for a highly tuned turbo - but it only effects low powered running when the piston has not expanded so much as it will when under full power so for track work and racing it makes little difference as long as the cooling system is sufficient to compensate for slightly lower thermal conductivity with iron.
It's a real shame that the problems that emerged initially with the Boxster and 996 3.4 IMS bearings, cracked and "D" chunked cylinders and later scored bores presented too good an opportunity in volume and lifespan terms to ignore shifting attention to those projects - because I am still sure the overall strength of the 944/968 construction would have stood the power we planned to create.
Baz
Blade, feel free to PM if you're interested as I have new, unused & in the box Wossner 8:1 pistons for a 100.5 alusil bore, matching Wossner rods & ViPec V88 ECU. The Wossners are for a 2.5 litre. Would work fine for an engine refresh such as building a 2.5 litre with a different turbo.
IMHO I don't like dry alloy Nikasil plated liners because two tubes inside one another create a flexible structure compared to one tube of the major and minor diameter of the other 2 put together. If you want a fishing rod fit tubes inside each other!
Similarly even with ferrous dry liners - although the iron is stiff you have to make the exterior alloy thinner to make space for the liner and this means that when the thrust pressure pushes the iron against the alloy it more easily stretches it until the fit is less tight and of course the interface between the two dissimilar materials reduces heat transfer. This is why if you are going to have iron liners I like the Darton type design of a wet liner supported at the top (if possible) although an aerospace alloy ribbed and Nikasil plated wet liner of a similar design is IMHO superior.
it is very important when messing with any forced charge system however that the actual compression ratio is calculated and built in from scratch with the final boost pressure taken into account. Our original 3 litre engine was deigned for torque to prove a point about drivability and despite 300BHP and 350 lbs ft torque (on standard turbo) hardly ever spun up the wheels on full throttle due to the flatter torque curve from lower revs.
We were aiming for over 500 bhp with this engine and good torque as well but the turbo and intercooler would have been huge and the static (or geometric) compression ratio would be quite low to avoid detonation.
Baz
Similarly even with ferrous dry liners - although the iron is stiff you have to make the exterior alloy thinner to make space for the liner and this means that when the thrust pressure pushes the iron against the alloy it more easily stretches it until the fit is less tight and of course the interface between the two dissimilar materials reduces heat transfer. This is why if you are going to have iron liners I like the Darton type design of a wet liner supported at the top (if possible) although an aerospace alloy ribbed and Nikasil plated wet liner of a similar design is IMHO superior.
it is very important when messing with any forced charge system however that the actual compression ratio is calculated and built in from scratch with the final boost pressure taken into account. Our original 3 litre engine was deigned for torque to prove a point about drivability and despite 300BHP and 350 lbs ft torque (on standard turbo) hardly ever spun up the wheels on full throttle due to the flatter torque curve from lower revs.
We were aiming for over 500 bhp with this engine and good torque as well but the turbo and intercooler would have been huge and the static (or geometric) compression ratio would be quite low to avoid detonation.
Baz
Sounds good.
It's a slippery slope which can quickly become budget-busting.
I also have a new, unused in the box Garrett GTX3071R Gen I and a GTX3071R Gen II turbos for whoever might be interested - just PM me. Hotsides are Tial 0.82 on both & a spare1.06. All still in the box!
I like the short stroke engine - it's sweet, free-revving and smooth.
It's a slippery slope which can quickly become budget-busting.
I also have a new, unused in the box Garrett GTX3071R Gen I and a GTX3071R Gen II turbos for whoever might be interested - just PM me. Hotsides are Tial 0.82 on both & a spare1.06. All still in the box!
I like the short stroke engine - it's sweet, free-revving and smooth.
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