3.0 Liter turbo conversions-Experienced builders please reply
12-12-2003, 04:33 PM
#31
Chris - is your car black (maybe dark blue) and have a GT3 sticker under the hood? If so where did you get the intake? Nicest sheet metal one I think I have ever seen.
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12-13-2003, 02:24 AM
#32
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What are the downsides if any of simply using a 2.7L head on a 3.0L stock complete S2 short block, and using a high-quality thicker head gasket (copper, perhaps?), with wide fire rings, to lower the compression ratio?
This scenario would be for a street application with modest horsepower goals, using stock 951 engine management.
This scenario would be for a street application with modest horsepower goals, using stock 951 engine management.
12-13-2003, 06:28 AM
#33
Nordschleife Master
How about taking an S2 short block, leave the pistons untouched, change the rods to 951-ones and install a mody 951-head with all the compression ratio lowering done to the head's combustion chamber?
This concept is done by a Swedish enginebuilder. I'd like to hear some comments about it!
This concept is done by a Swedish enginebuilder. I'd like to hear some comments about it!
12-13-2003, 10:17 AM
#34
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The last to suggestions are possible…but not optimal.
If budget were the constraining factor (and when isn’t it?!!) I would spend the limited money on a good turbo and a good engine management system rather than the ‘shoe string’ 3.0 engine. There are so many ‘not quite right’ issues – squish chamber shape, extra thick headgaskets, compression ratios and such that it would be a hit and miss engineer effort. Sure, you would get some more torque than a stock or slightly modified 2.5 but you won’t see a linear gain and the long term reliability would be in question. I would definitely not recommend it for track use (sorry – I am biased, that is where I have my fun so I am always considering some serious duty for any modification).
Also – either of these mods will really need some dyno time to dial in, your dyno budget could be 50% of the project, especially if you are reburning chips each time.
With 370rwhp (reliable - sub 20 psi) available for the cost of a turbo, intercooler pipes and engine management what are you looking to get with the 3.0 set up?
Chris White
PS – nope, that’s not my GT3, I think you are talking about the Norwood creation – nice piece of work (especially with the cleverly written Excellence article that leaves the reader thinking that it was running 10:1 CR….)
If budget were the constraining factor (and when isn’t it?!!) I would spend the limited money on a good turbo and a good engine management system rather than the ‘shoe string’ 3.0 engine. There are so many ‘not quite right’ issues – squish chamber shape, extra thick headgaskets, compression ratios and such that it would be a hit and miss engineer effort. Sure, you would get some more torque than a stock or slightly modified 2.5 but you won’t see a linear gain and the long term reliability would be in question. I would definitely not recommend it for track use (sorry – I am biased, that is where I have my fun so I am always considering some serious duty for any modification).
Also – either of these mods will really need some dyno time to dial in, your dyno budget could be 50% of the project, especially if you are reburning chips each time.
With 370rwhp (reliable - sub 20 psi) available for the cost of a turbo, intercooler pipes and engine management what are you looking to get with the 3.0 set up?
Chris White
PS – nope, that’s not my GT3, I think you are talking about the Norwood creation – nice piece of work (especially with the cleverly written Excellence article that leaves the reader thinking that it was running 10:1 CR….)
12-13-2003, 03:57 PM
#35
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What specific technical problems are there to consider when using the thicker head gasket? This has been a time-proven technique with other marques; are there any special concerns with our cars? Or is simply a matter of not having been done by many folks, and thus not much info out there, since the stroker kit technique is what is mainly done?
I would hazard a guess that if it were to prove problematic, the main "risk" is in blowing the gasket itself, or simply getting a "gasket blowby" effect. I always look at the head gasket as kind of like the "clutch" of the engine itself, i.e., the weak link that you can afford to blow. It might be worth the experiment if there is no great volume of experience out there with it in Porsche cars. If it works, it represents one hell of a cheaper and easier way to lower the CR and take it easy on the engine.
I would hazard a guess that if it were to prove problematic, the main "risk" is in blowing the gasket itself, or simply getting a "gasket blowby" effect. I always look at the head gasket as kind of like the "clutch" of the engine itself, i.e., the weak link that you can afford to blow. It might be worth the experiment if there is no great volume of experience out there with it in Porsche cars. If it works, it represents one hell of a cheaper and easier way to lower the CR and take it easy on the engine.
12-13-2003, 07:26 PM
#36
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Mr. White is right when you think about it. . .
What is the highest form of endurance (not drag racing) race engine around - no holds barred - money no object? I'd think it would have to be a CART motor (800-900 HP). I dont have the book handy but I believe their displcement was limited to 1.65L - but they run 45 PSI boost and only developed real power above 13000 RPM. I also hear from a chassis designer employee that they would rather and are willing to let the displ. go down if they could run more boost (!).
With unlimted resources, they'ld rather figure out how to deal with the boost than make the engine bigger. I know there are a lot of other things involved with the formula, but I think there is wisdom in their approach.
Switch gears . . . I bought a car with a "rebuilt" sleeved motor - 2.7. It was a Garrity job and it was not right. At 13K miles upon tear down, it was showing signs of self-destruction. I'd have to equate it to the excessive clearances needed to comply with aftermarket factory specs on pistons and or pins. The pistons Garrity spec.ed for the motor called for .005" cyl to piston clearances if running under turbocharged applications - man, that's downright sloppy. Now, first of all, Garrity is no slouch in the machine shop. Say what you will about him, his machining is top-drawer. I have other examples of his work that are real nice compared to similar work done locally. Those pistons just expanded way too much. Whether for 104 mm (mine) or 106 mm , that clearance is what is advised. I'm also aware - out of John Anderson's own mouth - that he runs tighter clearances than JE spec. but how much, who knows? So compare that to new engine spec for a Porsche 951 stock piston : .0008" - .0012".
Mahle makes a much more dimensionally stable piston. Now you can put a forged J.E. or a Keith Black slug in a sleeve which is still going to want .003", but I think for $1200, the Mahle/Andial piston is worth it right off the bat for this reason alone. And this is just the first baby step into your megadollar motor.
The long and the short of it is, If you want to run bigger displacement over 1 bar for any servicable period of time (100K miles), you need to be able to throw down some major scratch. It's not that it's a bad premise, but it seems to me you can go further if you are running 25 PSI in a 2.5 (ala Rage) than 16 PSI in a 3.whatever L. If you can do both - have the money - then great.
What is the highest form of endurance (not drag racing) race engine around - no holds barred - money no object? I'd think it would have to be a CART motor (800-900 HP). I dont have the book handy but I believe their displcement was limited to 1.65L - but they run 45 PSI boost and only developed real power above 13000 RPM. I also hear from a chassis designer employee that they would rather and are willing to let the displ. go down if they could run more boost (!).
With unlimted resources, they'ld rather figure out how to deal with the boost than make the engine bigger. I know there are a lot of other things involved with the formula, but I think there is wisdom in their approach.
Switch gears . . . I bought a car with a "rebuilt" sleeved motor - 2.7. It was a Garrity job and it was not right. At 13K miles upon tear down, it was showing signs of self-destruction. I'd have to equate it to the excessive clearances needed to comply with aftermarket factory specs on pistons and or pins. The pistons Garrity spec.ed for the motor called for .005" cyl to piston clearances if running under turbocharged applications - man, that's downright sloppy. Now, first of all, Garrity is no slouch in the machine shop. Say what you will about him, his machining is top-drawer. I have other examples of his work that are real nice compared to similar work done locally. Those pistons just expanded way too much. Whether for 104 mm (mine) or 106 mm , that clearance is what is advised. I'm also aware - out of John Anderson's own mouth - that he runs tighter clearances than JE spec. but how much, who knows? So compare that to new engine spec for a Porsche 951 stock piston : .0008" - .0012".
Mahle makes a much more dimensionally stable piston. Now you can put a forged J.E. or a Keith Black slug in a sleeve which is still going to want .003", but I think for $1200, the Mahle/Andial piston is worth it right off the bat for this reason alone. And this is just the first baby step into your megadollar motor.
The long and the short of it is, If you want to run bigger displacement over 1 bar for any servicable period of time (100K miles), you need to be able to throw down some major scratch. It's not that it's a bad premise, but it seems to me you can go further if you are running 25 PSI in a 2.5 (ala Rage) than 16 PSI in a 3.whatever L. If you can do both - have the money - then great.
12-13-2003, 07:39 PM
#37
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Originally posted by Matt Sheppard
Mr. White is right when you think about it. . .
What is the highest form of endurance (not drag racing) race engine around - no holds barred - money no object? I'd think it would have to be a CART motor (800-900 HP). I dont have the book handy but I believe their displcement was limited to 1.65L - but they run 45 PSI boost and only developed real power above 13000 RPM. I also hear from a chassis designer employee that they would rather and are willing to let the displ. go down if they could run more boost (!).
With unlimted resources, they'ld rather figure out how to deal with the boost than make the engine bigger. I know there are a lot of other things involved with the formula, but I think there is wisdom in their approach.
Mr. White is right when you think about it. . .
What is the highest form of endurance (not drag racing) race engine around - no holds barred - money no object? I'd think it would have to be a CART motor (800-900 HP). I dont have the book handy but I believe their displcement was limited to 1.65L - but they run 45 PSI boost and only developed real power above 13000 RPM. I also hear from a chassis designer employee that they would rather and are willing to let the displ. go down if they could run more boost (!).
With unlimted resources, they'ld rather figure out how to deal with the boost than make the engine bigger. I know there are a lot of other things involved with the formula, but I think there is wisdom in their approach.
The idea was floated to reduce displacement and increase boost, so that a easy boost reduction could be performed if power outputs got out of hand.
Unfortunately, CART is on their death bed and top level open wheel road racing in North America is about to take a serious sabbatical.
12-13-2003, 07:46 PM
#38
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Well, shows you my reading comprehension level. . . The 2.65 I remember, the 3 PSI is not what I remember published, I assure you. What boost is F1 running? Did I at least get the HP figure right?
12-13-2003, 07:52 PM
#39
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Originally posted by Matt Sheppard
What boost is F1 running?
What boost is F1 running?
They are however around 900 hp.
12-13-2003, 08:04 PM
#40
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The horsepower levels you mentioned are, or at least were correct.
As for the maximum manifold pressure, it has always been stated as absolute pressure in inches of mercury, though announcers and articles may state it somewhat misleadingly in just inches.
The conversion factors are as follows:
inches of mercury x 0.4912 = psi
inches of mercury x 0.03386 = bars
So, 37 inches of mercury = 18.2 psi = 1.25 bar. These numbers are absolute, so the "boost" would actually be 3.5 psi or .25 bar.
~5 years ago, the maximum manifold pressure was 45 inches of mercury, which is 22.1 psi or 1.52 bar. In other words, 7.4 psi or .52 bar boost.
Also, it is worth noting that they run their engines on methanol.
As for the maximum manifold pressure, it has always been stated as absolute pressure in inches of mercury, though announcers and articles may state it somewhat misleadingly in just inches.
The conversion factors are as follows:
inches of mercury x 0.4912 = psi
inches of mercury x 0.03386 = bars
So, 37 inches of mercury = 18.2 psi = 1.25 bar. These numbers are absolute, so the "boost" would actually be 3.5 psi or .25 bar.
~5 years ago, the maximum manifold pressure was 45 inches of mercury, which is 22.1 psi or 1.52 bar. In other words, 7.4 psi or .52 bar boost.
Also, it is worth noting that they run their engines on methanol.
12-13-2003, 08:17 PM
#41
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Matt S - I agree with what you are saying overall, trivia debates aside. My money says there is a significant chance of grenading an engine put together from some 944 stock components, but assembled by a guy in a shop somewhere, regardless of his abilities. This is why, to me, and painting very broad strokes here, the best way is to stick with stock assemblies as much as possible, i.e., keep as much of the engine as it came from the factory as you are able.
I'd wager that quite a few guys are running higher than stock boost on 2.5L engine systems with no problems (disclaimer: of course with engine mangament well sorted, etc.) Look at the success Anderson is having in using low-boost systems on the high compression 3.0L engines. Look at the power Callaway made with turbocharging the early NA 944s with only dishing of the pistons to lower the CR.
My point being that from where I sit, the factory assembled engines in the 944/951 series seem pretty damn well screwed together. I have MUCH less faith in taking a 944 block and making a big displacement engine with aftermarket components, than perhaps taking a good factory-assembled S2 bottom end and a good factory-assembled 2/7L head, sandwiching a high-quality thicker head gasket between them to drop the CR, and having a 3.0L turbo-ready engine that was mostly assembled in Germany by the factory.
I think this is the technique I am going to experiment with, because I feel it will retain the most possible factory reliability and also happens to be the cheapest (cost of the gasket and fasteners). Any specific technical disagreements??
I'd wager that quite a few guys are running higher than stock boost on 2.5L engine systems with no problems (disclaimer: of course with engine mangament well sorted, etc.) Look at the success Anderson is having in using low-boost systems on the high compression 3.0L engines. Look at the power Callaway made with turbocharging the early NA 944s with only dishing of the pistons to lower the CR.
My point being that from where I sit, the factory assembled engines in the 944/951 series seem pretty damn well screwed together. I have MUCH less faith in taking a 944 block and making a big displacement engine with aftermarket components, than perhaps taking a good factory-assembled S2 bottom end and a good factory-assembled 2/7L head, sandwiching a high-quality thicker head gasket between them to drop the CR, and having a 3.0L turbo-ready engine that was mostly assembled in Germany by the factory.
I think this is the technique I am going to experiment with, because I feel it will retain the most possible factory reliability and also happens to be the cheapest (cost of the gasket and fasteners). Any specific technical disagreements??
12-14-2003, 02:55 AM
#43
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If it doesn't prove workable, according to actual data not just others' theories, or after my own experience, then the next step will be to try lower CR pistons. The problem in getting info is that the guys with the experience (pro tuners) don't want to reveal the products of their R&D, especially if this has indeed worked but clearly isn't a money-maker like custom engine work, and I guess a lot of shadetree mechanics aren't going to these lengths on their cars. So I may make a guinea pig out of my car.
My theory is to leave the 3L bottom end together as it left the factory, with the exception of replacing the rod bearings preventively, which I have already done. A respected tuner has been on record here as saying that the bottom end is good in stock (high) CR/low boost projects, so I am theorizing that it should also do fine in a lower CR/higher boost project.
Since I have to pull the head anyway to pop on the 2.7L head, the only major part changed out in this "simplest/cheapest" scenario is the head gasket and studs. I will be talking with EBS and some others next week and seeing what they stock vs can fabricate. This gives me an engine that was mostly put together in Neckarsulm...
I am theorizing that this method just hasn't been tried on our cars. However, what I am looking for is conclusive data to the contrary. I believe that historically what everyone is doing is jumping right to swapping pistons, rods, etc., which is great if done absolutely right, just proposing a different way that has been very workable in other marques.
My theory is to leave the 3L bottom end together as it left the factory, with the exception of replacing the rod bearings preventively, which I have already done. A respected tuner has been on record here as saying that the bottom end is good in stock (high) CR/low boost projects, so I am theorizing that it should also do fine in a lower CR/higher boost project.
Since I have to pull the head anyway to pop on the 2.7L head, the only major part changed out in this "simplest/cheapest" scenario is the head gasket and studs. I will be talking with EBS and some others next week and seeing what they stock vs can fabricate. This gives me an engine that was mostly put together in Neckarsulm...
I am theorizing that this method just hasn't been tried on our cars. However, what I am looking for is conclusive data to the contrary. I believe that historically what everyone is doing is jumping right to swapping pistons, rods, etc., which is great if done absolutely right, just proposing a different way that has been very workable in other marques.
12-14-2003, 10:22 AM
#44
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Modern turbo cars run in excess of 10:1 CR.
With 2,5L head you are down to 9:1.
I don't know if 2,7L head is smaller.
You have to modify the combustion chamber to fit with 104mm bore. With som more relief around the valves and on the side of the plug you can get close to 8,5:1.
You can get all the Squish that the pistons allow.
Then you just lower the advance a bit and you are home.
Skip the thicker gasket. Stock is just fine if your ignition and AFR is correct.
You can make more top end power with lower CR and more boost but isn't it nicer with less lag. Power will be quite impressive (I hesitate to say sufficient) anyhow with the right turbo.
Bengt
Modern turbo cars run in excess of 10:1 CR.
With 2,5L head you are down to 9:1.
I don't know if 2,7L head is smaller.
You have to modify the combustion chamber to fit with 104mm bore. With som more relief around the valves and on the side of the plug you can get close to 8,5:1.
You can get all the Squish that the pistons allow.
Then you just lower the advance a bit and you are home.
Skip the thicker gasket. Stock is just fine if your ignition and AFR is correct.
You can make more top end power with lower CR and more boost but isn't it nicer with less lag. Power will be quite impressive (I hesitate to say sufficient) anyhow with the right turbo.
Bengt
12-14-2003, 01:20 PM
#45
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Bengt - thanks for the info. I also wish I knew more about the effects on CR and the overall parameters of putting the 2.7L head onto the S2 block. It would indeed be wonderful if the CR ended up somewhere around 9.0:1 with the 2.7L head, but my money says it won't - I am conjecturing that I would be recreating the 2.7L NA engine's CR with this setup when using a normal head gasket.
If I read you right, I think you were also saying that modification will need to be done to the 2.5L head if used on the S2 block, which is of course right, but I will not be going that route. If I do this project (looks like I will), I will be getting a 2.7L head one way or another.
Which points me back at the thicker gasket, since I don't want to mess with the stock bottom end and definitely want the reliability that the lower CR brings, with of course some throttle sharpness lost in the tradeoff.
Looks like I'm on my own!
If I read you right, I think you were also saying that modification will need to be done to the 2.5L head if used on the S2 block, which is of course right, but I will not be going that route. If I do this project (looks like I will), I will be getting a 2.7L head one way or another.
Which points me back at the thicker gasket, since I don't want to mess with the stock bottom end and definitely want the reliability that the lower CR brings, with of course some throttle sharpness lost in the tradeoff.
Looks like I'm on my own!