944 engine weaknesses
11-02-2009, 09:30 PM
#1
Banned
Thread Starter
Join Date: Dec 2002
Posts: 2,379
Likes: 0
Received 0 Likes
on
0 Posts
944 engine weaknesses
i'm learning all i can about 944 engines... i'd like to open a civil discussion about the facts about the weaknesses in the 944 engine that makes it so expensive to get greater than 500whp when compared to an engine like an audi i5 20v or an ls1.
i'd like to identify the specific weaknesses and then determine ways to fix them that are less expensive and troublesome than putting in a ls1.
any specific facts are appreciated.
the things i've heard (but don't know are facts) are:
1) weak bottom end (im not sure what this specifically means, however)
2) cylinder head flexes and warps
3) weak internals like rods and crank
4) low flowing head
my idea is to find some off the beaten path structural mods that can be done more or less cheaply to make the engine able to handle higher boost like the audi i5 like this audi with 40psi and over 700whp.
http://www.80tq.com/20vtMotor.html
i'd like to identify the specific weaknesses and then determine ways to fix them that are less expensive and troublesome than putting in a ls1.
any specific facts are appreciated.
the things i've heard (but don't know are facts) are:
1) weak bottom end (im not sure what this specifically means, however)
2) cylinder head flexes and warps
3) weak internals like rods and crank
4) low flowing head
my idea is to find some off the beaten path structural mods that can be done more or less cheaply to make the engine able to handle higher boost like the audi i5 like this audi with 40psi and over 700whp.
http://www.80tq.com/20vtMotor.html
11-02-2009, 11:01 PM
#2
Rennlist Member
Umm... I'm no engine expert, but I have a hunch that the primary limitation of the 944 engine, when compared to an LS1, is: it's a whole lot freakin' smaller and has only half the number of cylinders!!
I mean, seriously, a 944 is 2.5 liters. I think an LS1 is 5.7 liters. A 500 HP 944 engine would be equal to an 1,100 HP LS1! How many of those do you see? I know of some, but they're not common and they cost a lot.
I mean, seriously, a 944 is 2.5 liters. I think an LS1 is 5.7 liters. A 500 HP 944 engine would be equal to an 1,100 HP LS1! How many of those do you see? I know of some, but they're not common and they cost a lot.
11-02-2009, 11:07 PM
#3
Team Owner
Join Date: Oct 2009
Location: one thousand, five hundred miles north of Ft. Lauderdale for the summer.
Posts: 28,704
Received 212 Likes
on
153 Posts
An Audi 20 valve turbo engine would have theoretically been THE perfect engine for the 944/968. i dreamed of being the first to do it 15 years ago. But I was tied up in other things... ballancing is a problem with all inline engines. V8s and V12s offer the least offence to the laws of physics. inline 6 engines RULE for off-road and towing.
Crate 364 cubic inch Chevy LS2:
heads ported by Total Engine Airflow, Fast 90 mm intake, upgrade valve train components and Comp Cams mild cam. about 9,000 dollars -- 565 hp.
just a bit choppy at idle, and an engine you can have running for 30, 40 years if you treat it nice and not beat on it.
Going past that requires big budgets and new transmissions, axles, torque tubes, etc.
Crate 364 cubic inch Chevy LS2:
heads ported by Total Engine Airflow, Fast 90 mm intake, upgrade valve train components and Comp Cams mild cam. about 9,000 dollars -- 565 hp.
just a bit choppy at idle, and an engine you can have running for 30, 40 years if you treat it nice and not beat on it.
Going past that requires big budgets and new transmissions, axles, torque tubes, etc.
11-02-2009, 11:54 PM
#4
Team Owner
Ok, not an expert but built a lot of small block Chevys in my mis-spent youth and a couple of 911 engines a few years back;
I think lower end is fine. Check out that full girdle.
I don't think the head "flexes" but any engine with wet sleeves and no deck plate would be prone to possible problems if turned the boost up enough. Notice all the big boys (3.0 and up) seem to use deck plates or steel sleeves. The heads are about like a small block head but probably stiffer due to the very solid cam tower on top.
The lower end parts are all forged. The pistons are Mahle. All very good stuff.
Flow; well 8 valves in line (not a “hemi”). Can't dial in the "cams" just the cam. Don't have a lot of valves, cams to overlap timing or an advance mechanism. My daily is an Acura with all that plus iVTEC. These motors are 25 years + old. Oh yea, and engine management is also 25 years old but can be improved vastly but still you got what you got. Great cars that can make plenty of usable and fun power for a reasonable price.
I think lower end is fine. Check out that full girdle.
I don't think the head "flexes" but any engine with wet sleeves and no deck plate would be prone to possible problems if turned the boost up enough. Notice all the big boys (3.0 and up) seem to use deck plates or steel sleeves. The heads are about like a small block head but probably stiffer due to the very solid cam tower on top.
The lower end parts are all forged. The pistons are Mahle. All very good stuff.
Flow; well 8 valves in line (not a “hemi”). Can't dial in the "cams" just the cam. Don't have a lot of valves, cams to overlap timing or an advance mechanism. My daily is an Acura with all that plus iVTEC. These motors are 25 years + old. Oh yea, and engine management is also 25 years old but can be improved vastly but still you got what you got. Great cars that can make plenty of usable and fun power for a reasonable price.
11-02-2009, 11:56 PM
#5
Rennlist Member
A I5 20VT (AAN) has "weaker" internals than a 951 engine. The rods like to bend ~350whp whereas 951 internals are good to ~400whp. And since the 20VT has 5 cylinders compared to a 951's 4 the rods see less stress than the 951 but still fail before.
The 20VT head flows MUCH better than the 8V 951 engine. However, I am not sure how a 16V S2/968 head compares.
A I5 block is closed deck compared to the open deck of a 944 block so it is "stronger".
Like I said in the other thread, making 700whp out of a 20VT isn't easy nor is it cheap. It costs money to make lots of power regardless of the engine. Javad also has a lot of help and innovation from 034 Motorsports in his car...not something everyone has access too. Many people also don't have the budget for a build of the caliber needed so generally the highest horsepower cars you see out there are "shop" cars.
The 20VT head flows MUCH better than the 8V 951 engine. However, I am not sure how a 16V S2/968 head compares.
A I5 block is closed deck compared to the open deck of a 944 block so it is "stronger".
Like I said in the other thread, making 700whp out of a 20VT isn't easy nor is it cheap. It costs money to make lots of power regardless of the engine. Javad also has a lot of help and innovation from 034 Motorsports in his car...not something everyone has access too. Many people also don't have the budget for a build of the caliber needed so generally the highest horsepower cars you see out there are "shop" cars.
11-03-2009, 01:55 AM
#6
Race Car
IMO the biggest drawback with these engines is the open deck and the cylinder head flow.
I am also not a big fan of the aluminum cylinder walls. Having replaced pistons in the past with iron blocks I would like to feel as confident that the whole engine wasnt trashed due to a bad moment in tuning.
Having seen what a lean condition with these engines looks like I'll.... pass thank you
With that said though, I think they do a pretty darn good job for what they are.
I am also not a big fan of the aluminum cylinder walls. Having replaced pistons in the past with iron blocks I would like to feel as confident that the whole engine wasnt trashed due to a bad moment in tuning.
Having seen what a lean condition with these engines looks like I'll.... pass thank you
With that said though, I think they do a pretty darn good job for what they are.
11-03-2009, 02:58 AM
#7
Banned
Thread Starter
Join Date: Dec 2002
Posts: 2,379
Likes: 0
Received 0 Likes
on
0 Posts
A I5 20VT (AAN) has "weaker" internals than a 951 engine. The rods like to bend ~350whp whereas 951 internals are good to ~400whp. And since the 20VT has 5 cylinders compared to a 951's 4 the rods see less stress than the 951 but still fail before.
The 20VT head flows MUCH better than the 8V 951 engine. However, I am not sure how a 16V S2/968 head compares.
A I5 block is closed deck compared to the open deck of a 944 block so it is "stronger".
Like I said in the other thread, making 700whp out of a 20VT isn't easy nor is it cheap. It costs money to make lots of power regardless of the engine. Javad also has a lot of help and innovation from 034 Motorsports in his car...not something everyone has access too. Many people also don't have the budget for a build of the caliber needed so generally the highest horsepower cars you see out there are "shop" cars.
The 20VT head flows MUCH better than the 8V 951 engine. However, I am not sure how a 16V S2/968 head compares.
A I5 block is closed deck compared to the open deck of a 944 block so it is "stronger".
Like I said in the other thread, making 700whp out of a 20VT isn't easy nor is it cheap. It costs money to make lots of power regardless of the engine. Javad also has a lot of help and innovation from 034 Motorsports in his car...not something everyone has access too. Many people also don't have the budget for a build of the caliber needed so generally the highest horsepower cars you see out there are "shop" cars.
http://www.80tq.com/20vtMotor.html
-2309cc, 83mm bore, stock 86.4mm stroke 7A crank and block (bored to 83mm from 82.5mm)
-Port matched, flowed 7A head, 230cft at .4" lift, 28" water (stock was 188cfm). Machined for RS2 water manifold.
-O-ringed block, .005" proud, .065" 034Motorsport annealed copper head gasket with MLS, rubber coated sealing layers.
-83mm JE pistons, 144mm 034Motorsport rods, ARP 2000 rod bolts, ARP headstuds and crank bearing studs. 8.3:1 CR
-CAT Cams 272/264 cams with 11.2mm lift, 112d lobe center (adjustable). 415whp, currently running 7A cams, 395whp baseline)
-Custom 034EFI long runner header, T3 exh. flange, all 304 stainless including flanges, full 3" downpipe and exhaust system. Wastegate dump open to atmosphere. - Now running Production Piece
-Selection of turbos, 034EFI HIGH OUTPUT T3/T4E (capable of 550HP or 55Lbs per minute of flow, currently running 034EFI T3/T61 Hybrid. Future plans to run a Garrett GT35 or 40R. - Now runniing GT40R, future plans for GT42RS (current turbo)
-3B Intake manifold and throttle body - 034EFI High Output Intake Manifold with AAN Throttle Body current.
-Custom 034Motorsport/SPEC Sintered Iron Clutch with dual spring fingers, over 3000lbs clamping force.
-034EFI Stage IIc EFI system with direct fire (coil per cyl) ignition, sequential fuel injection, 75LB injectors
- 034EFI Garrett GT42Rs Turbo, 4"-3.5" downpipe, -10AN fuel feed line, dual 044 Motorsport Fuel pumps (these items are added on in phase 4 of the build for over 700whp)
Trending Topics
11-03-2009, 03:10 AM
#8
Banned
Thread Starter
Join Date: Dec 2002
Posts: 2,379
Likes: 0
Received 0 Likes
on
0 Posts
even more the guy at 80tq.com says about his motor before he started the big HP build:
what can we do to the 944 to try to emulate this engine?
This was a rusty junk yard motor that I got for almost free, making 400 crank HP even after likely more than 200k miles. ...... This was a rusty junk yard motor that I got for almost free, making 400 crank HP even after likely more than 200k miles.
11-03-2009, 04:22 AM
#9
Rennlist Member
Bearing in mind that when you want to generate BIG power with the i4 motor you need to change, upgrade, or modify most of the motor anyway (with reliability in mind) so we're not comparing the stock Porsche motor anyway. I have had some setbacks all the way through my builds...but I'm hanging onto the dream of getting my build into a car...just won't be anytime soon as there has been another major setback but not to do with the motor. Anyway, point being that my build has had just about everything possibly done to increase structural integrity and open up everything to increase the VE. 500hp won't be an issue, but remember what the Audi motor guys says, the car spins rubber at over 125mph!! This is seriously scary. So traction is as much an issue as power from the motor.
Bit OT but totally relevant.
Bit OT but totally relevant.
11-03-2009, 05:15 AM
#10
Rennlist Member
seems easy, why isnt it easy? this guy doesnt seem like some kind of racing professional or even that he has his own garage, just looks like its built out of his house, but thats what i see from the pics, but what do i know? not much to be honest... it just seems like a DIY job... the specs are below for over 700whp and its for a smaller displacement engine 2.2 liters or something... to get anything like this you have to spend upwards of $20,000-$30,000 on a 3.0 944turbo engine at powerhaus or another custom engine builder and i've only even heard of a couple 600whp 944's... ive even heard of a $65,000 944 turbo engine... the guy who make the 1000hp audi engine did it at his house... the audi engine builder says that these audi engines are the strongest in the world... here are the specs:
Like Sid said, the biggest weaknesses of the 944 engine is the open deck and head. A 944 revs to 6500-7000rpm whereas the Audi revs to 9000rpm.
If you compare this build to Special Tool's build I wouldn't say the Audi is much far ahead and isn't nearly as impressive. As stated before the Audi has 5 cylinders, so rods and pistons will see less stress than a 4 cylinder. Tool made 600whp at 6500rpm through a 2.5L 8v motor. The Audi made 700whp at 8000-8500rpm on a 2.3L 20v motor. If Tool had a 16V head and revved out as high as the Audi then I would put money on him making more power than it.
11-03-2009, 08:38 AM
#11
Addict
Rennlist Member
Rennlist Small
Business Sponsor
Rennlist Member
Rennlist Small
Business Sponsor
Not really flex, but you will get some lifting problems if you run into detonation.
Rods are very strong but a little heavy – they will support the power but the weight is not good for high RPM. Crank is fine as is for strength – a lot stronger than most cranks!
The 8v head flows quite well, especially in the mid range. Its not a high rpm performer – but that’s not what it was designed to do. With some head work it can flow very well (not as well as a 16v)
Keep in mind that the dyno queens that you are comparing the 944 engine to don’t make squat for power until 6k rpm pr higher. They also don’t make that kind of power for very long. Most 944 projects you see around here are built to make the rated power at usable rpms and for extended periods. Since I tend to track my cars and build engines with that in mind my engines need to be able to run at or near rated output for 30 minutes at a time…not 30 seconds! Big difference. Ask a dyno queen if he can run his engine at 80% of max power for 30 minutes…..
As for weakness – it’s the oiling system. It does not like high rpms and the oil can get quite not and thin if you don’t have enough cooling. That can aggravate the oiling of the rod bearings (#2 first). This is also aggravated by the corning and braking forces that the 944 can generate (higher than ‘typical’ cars and much higher than dyno queens!)
11-03-2009, 10:02 AM
#12
Addict
Rennlist Member
Rennlist Member
Join Date: May 2001
Location: Parral, Chihuahua, Mejico
Posts: 929
Likes: 0
Received 4 Likes
on
4 Posts
Crank and rods in a 951 are bulletproof below 7k rpm.
The advantage of an 8v turbo is, if it's not flowing enough, change the flow by changing the pressure.
If you are going to run lots of pressure, shuffle pin the head/sleeves.
The advantage of an 8v turbo is, if it's not flowing enough, change the flow by changing the pressure.
If you are going to run lots of pressure, shuffle pin the head/sleeves.
11-03-2009, 10:11 AM
#13
Team Owner
Chris, that was very good. I'll keep that one handy. Thanks.
11-03-2009, 10:15 AM
#14
Drive-by provocation guy
Rennlist Member
Rennlist Member
Join Date: Apr 2002
Location: NAS PAX River, by way of Orlando
Posts: 10,439
Likes: 0
Received 0 Likes
on
0 Posts
Nope, it will support quite a lot of power – 1,000hp would not be a problem for a dyno queen.
Not really flex, but you will get some lifting problems if you run into detonation.
Rods are very strong but a little heavy – they will support the power but the weight is not good for high RPM. Crank is fine as is for strength – a lot stronger than most cranks!
The 8v head flows quite well, especially in the mid range. Its not a high rpm performer – but that’s not what it was designed to do. With some head work it can flow very well (not as well as a 16v)
Keep in mind that the dyno queens that you are comparing the 944 engine to don’t make squat for power until 6k rpm pr higher. They also don’t make that kind of power for very long. Most 944 projects you see around here are built to make the rated power at usable rpms and for extended periods. Since I tend to track my cars and build engines with that in mind my engines need to be able to run at or near rated output for 30 minutes at a time…not 30 seconds! Big difference. Ask a dyno queen if he can run his engine at 80% of max power for 30 minutes…..
As for weakness – it’s the oiling system. It does not like high rpms and the oil can get quite not and thin if you don’t have enough cooling. That can aggravate the oiling of the rod bearings (#2 first). This is also aggravated by the corning and braking forces that the 944 can generate (higher than ‘typical’ cars and much higher than dyno queens!)
Not really flex, but you will get some lifting problems if you run into detonation.
Rods are very strong but a little heavy – they will support the power but the weight is not good for high RPM. Crank is fine as is for strength – a lot stronger than most cranks!
The 8v head flows quite well, especially in the mid range. Its not a high rpm performer – but that’s not what it was designed to do. With some head work it can flow very well (not as well as a 16v)
Keep in mind that the dyno queens that you are comparing the 944 engine to don’t make squat for power until 6k rpm pr higher. They also don’t make that kind of power for very long. Most 944 projects you see around here are built to make the rated power at usable rpms and for extended periods. Since I tend to track my cars and build engines with that in mind my engines need to be able to run at or near rated output for 30 minutes at a time…not 30 seconds! Big difference. Ask a dyno queen if he can run his engine at 80% of max power for 30 minutes…..
As for weakness – it’s the oiling system. It does not like high rpms and the oil can get quite not and thin if you don’t have enough cooling. That can aggravate the oiling of the rod bearings (#2 first). This is also aggravated by the corning and braking forces that the 944 can generate (higher than ‘typical’ cars and much higher than dyno queens!)
20+ year old daily driver on pump gas that makes 100hp per cylinder with mid level mods?
I have to say, in my opinon, that puts our car WAY ahead of 90% of the market.
As soon as I see other cars, new or old, making 100hp per cyl with no issues as a DD, then they will impress me.
How many co workers park their 500hp 5cyl Audi, or 600hp V6 or 800hp V8 next to your 951 in your parking lot? lol
11-03-2009, 10:34 AM
#15
Racer
Join Date: Feb 2005
Location: UK
Posts: 332
Likes: 0
Received 0 Likes
on
0 Posts
Some observations:-
944 engines are tougher than people make out. There are a fw cars in the uk that have been running over 400hp for years with no problems with any of the above.
Inherantly though the all aluminium design of the engine is not as strong as the cast iron audi block and as such your not going to see many 700hp 944's. The Audi engine isn't all fun and games though, it requires stronger rods to reach anything more than 400hp and i believe the rest of the internalls (crank etc) are only good for around 500hp so its not quite as simple as using a stock engine to reach those figures. The main flaw over a 944 though is that the block is WAY heavier than the 944T block so would ruin the ballance of the car. The 944 was primarily designed to be a decent handling track racer.
You can make the internals capable of 700hp or more in a 944 using inserted steel liners and a closed deck block (see pauls UK 3.2 thread for pics) but the weight of the internalls for such a large 4cylinder engine tend to mean your more likely to see massive torque figures than big hp. Still.. having owned one running only low boost I'd be very interested to see a 700hp audi in a race with a 500hp /550ft/lb 944.
944 engines are tougher than people make out. There are a fw cars in the uk that have been running over 400hp for years with no problems with any of the above.
Inherantly though the all aluminium design of the engine is not as strong as the cast iron audi block and as such your not going to see many 700hp 944's. The Audi engine isn't all fun and games though, it requires stronger rods to reach anything more than 400hp and i believe the rest of the internalls (crank etc) are only good for around 500hp so its not quite as simple as using a stock engine to reach those figures. The main flaw over a 944 though is that the block is WAY heavier than the 944T block so would ruin the ballance of the car. The 944 was primarily designed to be a decent handling track racer.
You can make the internals capable of 700hp or more in a 944 using inserted steel liners and a closed deck block (see pauls UK 3.2 thread for pics) but the weight of the internalls for such a large 4cylinder engine tend to mean your more likely to see massive torque figures than big hp. Still.. having owned one running only low boost I'd be very interested to see a 700hp audi in a race with a 500hp /550ft/lb 944.