Main weaknesses in the 944 turbo engine?
02-14-2008, 12:42 PM
#16
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John
Do you mind elaborating on your 5th point. What type of details need to be considered. How would you treat a engine build for a car that would be dual purpose track/street?
Do you mind elaborating on your 5th point. What type of details need to be considered. How would you treat a engine build for a car that would be dual purpose track/street?
02-14-2008, 01:06 PM
#17
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We were very fortunate on our track car for almost 3.5 years; flawless, but I would upgrade the rods, as we had #4 let go. Now with Wossner rods.
I also like teflon coated bearings in the track car. We have twin oil coolers, baffled pan(door), pick up tube modified, and cross drilled crank. We ran VR1 Racing oil, changed after every event - bearings looked great when we tore the engine down; just our experience and the car saw 16 sessions on some weekends with both Jim and myself at the track at the same time. Good luck.
I also like teflon coated bearings in the track car. We have twin oil coolers, baffled pan(door), pick up tube modified, and cross drilled crank. We ran VR1 Racing oil, changed after every event - bearings looked great when we tore the engine down; just our experience and the car saw 16 sessions on some weekends with both Jim and myself at the track at the same time. Good luck.
02-14-2008, 01:27 PM
#18
Race Director
Like others stated.
The main weakness of the 944 Turbo Motor are 944 Turbo owners cranking up the boost without getting the tune right and taking care of other parts of the motor to make sure they handle the power.
The main weakness of 944 NA motors (all styles) is #2 rod bearings. This applies to the Turbo cars too since the oiling system is the same. Spun rod bearings happen when there is not enough oil being supplied to the rod bearings. Their are many reasons for this and many improvements. The only "solution" is the very expensive dry sump conversion.
I will say that you can run for a long time and have lots of fun with 944 based wet sump motor. You just need to always watch the oil levels. I have created some "rod bearing" tips for 944 spec motor here on rennlist. Follow these even with Turbo cars and you will be great shape. It could still happen, but probably not. Of course Turbo motors can still fail if you try to push too much boost without attention to details.
The main weakness of the 944 Turbo Motor are 944 Turbo owners cranking up the boost without getting the tune right and taking care of other parts of the motor to make sure they handle the power.
The main weakness of 944 NA motors (all styles) is #2 rod bearings. This applies to the Turbo cars too since the oiling system is the same. Spun rod bearings happen when there is not enough oil being supplied to the rod bearings. Their are many reasons for this and many improvements. The only "solution" is the very expensive dry sump conversion.
I will say that you can run for a long time and have lots of fun with 944 based wet sump motor. You just need to always watch the oil levels. I have created some "rod bearing" tips for 944 spec motor here on rennlist. Follow these even with Turbo cars and you will be great shape. It could still happen, but probably not. Of course Turbo motors can still fail if you try to push too much boost without attention to details.
02-14-2008, 01:37 PM
#19
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There are many things that get addressed a bit differently between a street vs. race engine. Clearances, rods stk. vs. aftermarket, mods to deal with windage issues.. Bearings, half groove or full groove.. The list goes on......
Some mods work for both, some mods make sense one way or the other. A race engine will live a much harder life, every bit of attention makes a difference.
Each engine builder has a certain set of mods to use.
02-14-2008, 02:34 PM
#20
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Depending on the race class rules, some modifications may be illegal.
In general, for a 951 track car, there are a few things that must be addressed in order for the engine to live.
1 - Oiling system.
- Oil cooling is very important. Once the oil temps get too high the oil pressure drops. Also, once the oil pressure drops the oil gets even hotter. A secondary or a larger oil cooler is a must! A temp gauge to keep track of the temps is also a must.
- Oil starvation - Run low on oil and starve the oil pickup, and your engine is done. Checking the oil level is a must before every session. The 951 under track use will consume oil, even on a perfect engine! Oil type and weight play a big role on how much oil is consumed. Under heavy G-loads, there is a chance the oil pickup will be uncovered (oil starvation). There are a few things to address this. a- A baffled oil pan, there are many ways to doing this. b- A Accusump, I think this helps greatly and as a side benefit it can be used to prelube the engine. c- Cross drilling the crank - mixed results here.
Of course, the above mods will help the engine live a long time. However, none will cure the problem 100%. I have seen a spun bearing with Xdrilled cranks and baffled pans. A dry sump system will help prevent oil starvation.
2- Spun rod bearing - This can be attributed to the oil starvation. However it can also be caused be pre-detonation, where the rod bearing gets hammered (especially #2 bearing). There are certain changes that can be made to prevent this or eliminate the cause.
3- Blown head gasket - There are many causes to the HG failure. Improper head torque, improper tuning, incorrect octane for the application...
4- Tuning - Once you start modifying the 951, it must be tuned correctly. There are physical limitations; turbo size, octane level, boost... On the track race gas is a must! On a street car, you can get away with bad tuning. On the race track it'll bite you. There are no 2 cars that are 100% identical. A true race car will have its own unique tune parameters.
5- Engine preps - there are many little tricks that can be done to help the engine live longer under track use. Building a engine for street use differs from a track engine. Attention to minor details and understanding goes a long way.
6- Unaware driver - Mechanical failures will take place, not if but when. If the driver is able to detect the failure early enough, he/she can save the engine. Some of the variables I would want the driver to monitor and "understand": Oil temps, Water temps, Oil pressure, Air Fuel Ratio, Boost, RPM.
ex: If the AFR is showing 14:1 when it was previously showing 12:1, there is a problem. If the car is tuned to run 15psi, but you see 20psi on the gauge, there is a problem...
Running over 6700-6800 RPM on a stock engine for a long period is not healthy to the engine. The 951 engine is not a hi-revving engine, not in stock form.
7- Preventive maintenance - A good race shop, will have a schedule to follow. Some items will be safety related, some will be preventive maintenance (belts, fluids, oil analysis)...
The 951 will live a long time on the track, however it requires a bit more attention than other cars. I know of track cars that have 100-200 hours on the engine without a failure. I also know of cars that did not last a session.
Of course class rules will dictate what is considered a legal modification.
In general, for a 951 track car, there are a few things that must be addressed in order for the engine to live.
1 - Oiling system.
- Oil cooling is very important. Once the oil temps get too high the oil pressure drops. Also, once the oil pressure drops the oil gets even hotter. A secondary or a larger oil cooler is a must! A temp gauge to keep track of the temps is also a must.
- Oil starvation - Run low on oil and starve the oil pickup, and your engine is done. Checking the oil level is a must before every session. The 951 under track use will consume oil, even on a perfect engine! Oil type and weight play a big role on how much oil is consumed. Under heavy G-loads, there is a chance the oil pickup will be uncovered (oil starvation). There are a few things to address this. a- A baffled oil pan, there are many ways to doing this. b- A Accusump, I think this helps greatly and as a side benefit it can be used to prelube the engine. c- Cross drilling the crank - mixed results here.
Of course, the above mods will help the engine live a long time. However, none will cure the problem 100%. I have seen a spun bearing with Xdrilled cranks and baffled pans. A dry sump system will help prevent oil starvation.
2- Spun rod bearing - This can be attributed to the oil starvation. However it can also be caused be pre-detonation, where the rod bearing gets hammered (especially #2 bearing). There are certain changes that can be made to prevent this or eliminate the cause.
3- Blown head gasket - There are many causes to the HG failure. Improper head torque, improper tuning, incorrect octane for the application...
4- Tuning - Once you start modifying the 951, it must be tuned correctly. There are physical limitations; turbo size, octane level, boost... On the track race gas is a must! On a street car, you can get away with bad tuning. On the race track it'll bite you. There are no 2 cars that are 100% identical. A true race car will have its own unique tune parameters.
5- Engine preps - there are many little tricks that can be done to help the engine live longer under track use. Building a engine for street use differs from a track engine. Attention to minor details and understanding goes a long way.
6- Unaware driver - Mechanical failures will take place, not if but when. If the driver is able to detect the failure early enough, he/she can save the engine. Some of the variables I would want the driver to monitor and "understand": Oil temps, Water temps, Oil pressure, Air Fuel Ratio, Boost, RPM.
ex: If the AFR is showing 14:1 when it was previously showing 12:1, there is a problem. If the car is tuned to run 15psi, but you see 20psi on the gauge, there is a problem...
Running over 6700-6800 RPM on a stock engine for a long period is not healthy to the engine. The 951 engine is not a hi-revving engine, not in stock form.
7- Preventive maintenance - A good race shop, will have a schedule to follow. Some items will be safety related, some will be preventive maintenance (belts, fluids, oil analysis)...
The 951 will live a long time on the track, however it requires a bit more attention than other cars. I know of track cars that have 100-200 hours on the engine without a failure. I also know of cars that did not last a session.
Of course class rules will dictate what is considered a legal modification.
Awesome response, thank you for taking the time I am sure you just made alot of us smarter!!
tom
02-14-2008, 02:35 PM
#21
Rennlist Member
Thread Starter
BTW - sleeved engines and aftermarket pistons are accepable even in stock class - if you do it the correct way with approved suppliers.
Rather than post a lot of stuff here - feel free to call or drop a line with any questions -
315-636-8716
chris@944enhancment.com
Chris White
Rather than post a lot of stuff here - feel free to call or drop a line with any questions -
315-636-8716
chris@944enhancment.com
Chris White
tom
02-14-2008, 02:52 PM
#22
Rennlist Member
Thread Starter
We were very fortunate on our track car for almost 3.5 years; flawless, but I would upgrade the rods, as we had #4 let go. Now with Wossner rods.
I also like teflon coated bearings in the track car. We have twin oil coolers, baffled pan(door), pick up tube modified, and cross drilled crank. We ran VR1 Racing oil, changed after every event - bearings looked great when we tore the engine down; just our experience and the car saw 16 sessions on some weekends with both Jim and myself at the track at the same time. Good luck.
I also like teflon coated bearings in the track car. We have twin oil coolers, baffled pan(door), pick up tube modified, and cross drilled crank. We ran VR1 Racing oil, changed after every event - bearings looked great when we tore the engine down; just our experience and the car saw 16 sessions on some weekends with both Jim and myself at the track at the same time. Good luck.
Well my experience racing 944's is frequent failures on I guess not ideally prepped cars.
threw #2 piston through the block. many head gaskets, broken axles, warped heads, bent valves.
learned alot about cars, racing, and driving from the last two years of 944 racing and would like to field a competitive 951 that will hold together.
from what I have seen at the races there seems to be no end to the amount of $ that people will put into the 944 race cars. some could probably be running Cup cars!
thanks for the advise, I appreciate it.
02-14-2008, 02:56 PM
#23
Rennlist Member
Thread Starter
Like others stated.
The main weakness of the 944 Turbo Motor are 944 Turbo owners cranking up the boost without getting the tune right and taking care of other parts of the motor to make sure they handle the power.
The main weakness of 944 NA motors (all styles) is #2 rod bearings. This applies to the Turbo cars too since the oiling system is the same. Spun rod bearings happen when there is not enough oil being supplied to the rod bearings. Their are many reasons for this and many improvements. The only "solution" is the very expensive dry sump conversion.
I will say that you can run for a long time and have lots of fun with 944 based wet sump motor. You just need to always watch the oil levels. I have created some "rod bearing" tips for 944 spec motor here on rennlist. Follow these even with Turbo cars and you will be great shape. It could still happen, but probably not. Of course Turbo motors can still fail if you try to push too much boost without attention to details.
The main weakness of the 944 Turbo Motor are 944 Turbo owners cranking up the boost without getting the tune right and taking care of other parts of the motor to make sure they handle the power.
The main weakness of 944 NA motors (all styles) is #2 rod bearings. This applies to the Turbo cars too since the oiling system is the same. Spun rod bearings happen when there is not enough oil being supplied to the rod bearings. Their are many reasons for this and many improvements. The only "solution" is the very expensive dry sump conversion.
I will say that you can run for a long time and have lots of fun with 944 based wet sump motor. You just need to always watch the oil levels. I have created some "rod bearing" tips for 944 spec motor here on rennlist. Follow these even with Turbo cars and you will be great shape. It could still happen, but probably not. Of course Turbo motors can still fail if you try to push too much boost without attention to details.
Thanks Joe I will look that up.
02-14-2008, 04:44 PM
#25
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02-14-2008, 05:03 PM
#26
Race Director
Whatever you do, take the work to an engine builder with experience of the 951 engine. It might be a Porsche engine but most engine builders have very little experience when it comes to modified Porsche engines that are not 911-engines.
The 951 as a platform answers very well to knowledge, guts and cubic dollars when it comes to track cars that go fast.
The 951 as a platform answers very well to knowledge, guts and cubic dollars when it comes to track cars that go fast.
02-14-2008, 05:14 PM
#27
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Well my experience racing 944's is frequent failures on I guess not ideally prepped cars.
threw #2 piston through the block. many head gaskets, broken axles, warped heads, bent valves.
learned alot about cars, racing, and driving from the last two years of 944 racing and would like to field a competitive 951 that will hold together.
from what I have seen at the races there seems to be no end to the amount of $ that people will put into the 944 race cars. some could probably be running Cup cars!
thanks for the advise, I appreciate it.
threw #2 piston through the block. many head gaskets, broken axles, warped heads, bent valves.
learned alot about cars, racing, and driving from the last two years of 944 racing and would like to field a competitive 951 that will hold together.
from what I have seen at the races there seems to be no end to the amount of $ that people will put into the 944 race cars. some could probably be running Cup cars!
thanks for the advise, I appreciate it.
It is entirely possible to do the build right without spending way way too much money.
02-14-2008, 05:32 PM
#28
Drifting
That's a fact.
02-14-2008, 05:44 PM
#29
Race Director
I think the main weakness is a bad PO
x2
x2
02-14-2008, 05:58 PM
#30
Tom,
There's a lot of guys getting some very impressive performance out of highly tuned 951 engines, but SP3 is basically a stock class. No internal engine mods aside from regular maintenance items including factors overbores. Before you start spending to get the cylinders honed to #1 overbore, it might be better to find a good clean block and build up a solid stock engine. There are some 'must do' things for your list:
- check the crank carefully, and replace the rod bearings
- get a Turbo S pan baffle
- Take the heater core out of circuit, and run a line from the heater take-off back around to the water pump to avoid hot spots at the back of the head. This will save you an early head gasket job.
- Install an additional oil cooler [the KISS cooler is a good option] and an oil temp gauge
- watch carefully for signs of blow-by oil. The turbo seals can leak, and a rebuild is the answer.
- become religious about using good oil [Redline 50 weight is my personal poison], and checking it after every session. Fill slightly above the high mark on the stick.
I've run three seasons of 944 SuperCup plus a ton of PCA DEs with nothing more than this, and aside from a head gasket the engine has been faultless. They can be super reliable even when running very hard. The key is to start with a good basic engine build and keep a close eye on oil levels and temps.
There's a lot of guys getting some very impressive performance out of highly tuned 951 engines, but SP3 is basically a stock class. No internal engine mods aside from regular maintenance items including factors overbores. Before you start spending to get the cylinders honed to #1 overbore, it might be better to find a good clean block and build up a solid stock engine. There are some 'must do' things for your list:
- check the crank carefully, and replace the rod bearings
- get a Turbo S pan baffle
- Take the heater core out of circuit, and run a line from the heater take-off back around to the water pump to avoid hot spots at the back of the head. This will save you an early head gasket job.
- Install an additional oil cooler [the KISS cooler is a good option] and an oil temp gauge
- watch carefully for signs of blow-by oil. The turbo seals can leak, and a rebuild is the answer.
- become religious about using good oil [Redline 50 weight is my personal poison], and checking it after every session. Fill slightly above the high mark on the stick.
I've run three seasons of 944 SuperCup plus a ton of PCA DEs with nothing more than this, and aside from a head gasket the engine has been faultless. They can be super reliable even when running very hard. The key is to start with a good basic engine build and keep a close eye on oil levels and temps.
Last edited by APKhaos; 02-14-2008 at 10:11 PM.