Smaller Displacement = Higher popssible Horsepower?
05-05-2007, 10:57 AM
#31
Rennlist Member
Join Date: Feb 2003
Location: Chicago
Posts: 3,526
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Porschefile
There is, it's called Volumetric Efficiency! 
Honestly, I'm pretty unimpressed with a majority of the turbo 3.0l's (God, don't even get me started on 8v 3.0l's!) and 2.8l's I've seen here for that exact reason. It seems that about 98% of the people that build them don't do any other kind of supporting mods to increase VE (head porting, custom cam(s), etc), so you end up with a motor that makes somewhat improved low-end and mid range, but you still have NO top-end power curve. In many cases, I'd say people's money would be much better spent on VE mods (intake/exhaust, head mods, etc) than displacement increases, and in many cases it would probably be more cost effective. I don't know about anyone else but, personally I'd rather my engine work more efficiently. Just remember, horsepower is what moves a car, not torque. 
Guns, your car should NOT idle at 3-4k. Doing so doesn't serve any real purpose except to sound REALLY loud at idle. Even with crazy, hot, long duration cams, you should only need the idle set at around 1-1.5k rpm.
An S2 or 968 motor would have a huge advantage for this as the 16v head would help a ton.
Honestly, I'm pretty unimpressed with a majority of the turbo 3.0l's (God, don't even get me started on 8v 3.0l's!) and 2.8l's I've seen here for that exact reason. It seems that about 98% of the people that build them don't do any other kind of supporting mods to increase VE (head porting, custom cam(s), etc), so you end up with a motor that makes somewhat improved low-end and mid range, but you still have NO top-end power curve. In many cases, I'd say people's money would be much better spent on VE mods (intake/exhaust, head mods, etc) than displacement increases, and in many cases it would probably be more cost effective. I don't know about anyone else but, personally I'd rather my engine work more efficiently. Just remember, horsepower is what moves a car, not torque. Guns, your car should NOT idle at 3-4k. Doing so doesn't serve any real purpose except to sound REALLY loud at idle.
Even with crazy, hot, long duration cams, you should only need the idle set at around 1-1.5k rpm.An S2 or 968 motor would have a huge advantage for this as the 16v head would help a ton.
05-05-2007, 11:25 AM
#32
Addict
Rennlist Member
Rennlist Member
Originally Posted by Guns951
Porschefile: I'm setting the idle that high because I don't want to wait for eternity to get the turbo to spool, plus it will sound cool I know it doesn't have to be that high but why not right?
944kid: Glad I could help, I just would hate to see someone get their hopes up about a goal like that only to find out its much more difficult than expected etc. Its your thread, you wanted info, so I'll give you what the truth is, looking for more power is a slippery slope - but the main thing if you want to go really fast, improve the driver first. Get good driver training etc, learn how to drive a "momentum car" ie a NA 944, then move to the higher bhp cars. Best of luck to you.
I know it doesn't have to be that high but why not right?944kid: Glad I could help, I just would hate to see someone get their hopes up about a goal like that only to find out its much more difficult than expected etc. Its your thread, you wanted info, so I'll give you what the truth is, looking for more power is a slippery slope - but the main thing if you want to go really fast, improve the driver first. Get good driver training etc, learn how to drive a "momentum car" ie a NA 944, then move to the higher bhp cars. Best of luck to you.
05-05-2007, 11:39 AM
#33
Race Car
Join Date: May 2005
Location: Being censored by a Moderator
Posts: 4,074
Likes: 0
Received 1 Like
on
1 Post
Yeah, so? I want the idle high to be reminicient of the old school racers. So I cause extra clutch wear, no biggie. I'm planning on replacing stuff WAY more often then normal to get the feeling I want out of it.
05-05-2007, 12:05 PM
#34
Rennlist Member
Originally Posted by Porschefile
There is, it's called Volumetric Efficiency! Honestly, I'm pretty unimpressed with a majority of the turbo 3.0l's (God, don't even get me started on 8v 3.0l's!) and 2.8l's I've seen here for that exact reason. It seems that about 98% of the people that build them don't do any other kind of supporting mods to increase VE (head porting, custom cam(s), etc), so you end up with a motor that makes somewhat improved low-end and mid range, but you still have NO top-end power curve. In many cases, I'd say people's money would be much better spent on VE mods (intake/exhaust, head mods, etc) than displacement increases, and in many cases it would probably be more cost effective. I don't know about anyone else but, personally I'd rather my engine work more efficiently. Just remember, horsepower is what moves a car, not torque.
Guns, your car should NOT idle at 3-4k. Doing so doesn't serve any real purpose except to sound REALLY loud at idle. Even with crazy, hot, long duration cams, you should only need the idle set at around 1-1.5k rpm.
Trying to make a substantial amount of torque (like 600+lb/ft) at higher rpm (lets say 7.5-8k+ rpm) on an 8v is an extremely hard proposition. The head is so restrictive at that kind of rpm. Yeah, you can hog out the ports (bye bye low-end) but, you'll reach a point where torque is just going to plummet on the top end no matter what you do. That's the inherent inefficiency you have to deal with on these 8v's. The only choice you'd have is to run a F*ck ton of boost on a big turbo like a Gt4202r (Gt42RS), and by that I mean like 40+psi. Judging by all the calculations I've done in the past, I'd tend to think that even with a race port job and extremely long duration cams, by roughly 7.2 to 7.5k torque should already be dropping SIGNIFICANTLY. I don't think a lot of people realize just how restrictive these 8v heads are as far as overall design and airflow volume goes. I've seen well built Nissan motors with more efficient dual cam heads and Gt4202's running 43psi still barely break 760whp because the head is choking out on the top-end. For attempting to accomplish something like we're talking about here, these 8v motors suck major donkey *****. An S2 or 968 motor would have a huge advantage for this as the 16v head would help a ton.
Honestly, I'm pretty unimpressed with a majority of the turbo 3.0l's (God, don't even get me started on 8v 3.0l's!) and 2.8l's I've seen here for that exact reason. It seems that about 98% of the people that build them don't do any other kind of supporting mods to increase VE (head porting, custom cam(s), etc), so you end up with a motor that makes somewhat improved low-end and mid range, but you still have NO top-end power curve. In many cases, I'd say people's money would be much better spent on VE mods (intake/exhaust, head mods, etc) than displacement increases, and in many cases it would probably be more cost effective. I don't know about anyone else but, personally I'd rather my engine work more efficiently. Just remember, horsepower is what moves a car, not torque. Guns, your car should NOT idle at 3-4k. Doing so doesn't serve any real purpose except to sound REALLY loud at idle.
Even with crazy, hot, long duration cams, you should only need the idle set at around 1-1.5k rpm.Trying to make a substantial amount of torque (like 600+lb/ft) at higher rpm (lets say 7.5-8k+ rpm) on an 8v is an extremely hard proposition. The head is so restrictive at that kind of rpm. Yeah, you can hog out the ports (bye bye low-end) but, you'll reach a point where torque is just going to plummet on the top end no matter what you do. That's the inherent inefficiency you have to deal with on these 8v's. The only choice you'd have is to run a F*ck ton of boost on a big turbo like a Gt4202r (Gt42RS), and by that I mean like 40+psi. Judging by all the calculations I've done in the past, I'd tend to think that even with a race port job and extremely long duration cams, by roughly 7.2 to 7.5k torque should already be dropping SIGNIFICANTLY. I don't think a lot of people realize just how restrictive these 8v heads are as far as overall design and airflow volume goes. I've seen well built Nissan motors with more efficient dual cam heads and Gt4202's running 43psi still barely break 760whp because the head is choking out on the top-end. For attempting to accomplish something like we're talking about here, these 8v motors suck major donkey *****. An S2 or 968 motor would have a huge advantage for this as the 16v head would help a ton.
05-05-2007, 12:32 PM
#35
[/QUOTE] Yeah, so? I want the idle high to be reminicient of the old school racers. So I cause extra clutch wear, no biggie. I'm planning on replacing stuff WAY more often then normal to get the feeling I want out of it.
So you actually want to have to change clutches and other things routinely? what fun is that?
So you actually want to have to change clutches and other things routinely? what fun is that?
05-05-2007, 12:47 PM
#36
Drifting
Join Date: Apr 2005
Location: Elk Gove, CA
Posts: 3,400
Likes: 0
Received 0 Likes
on
0 Posts
Yeah, so? I want the idle high to be reminicient of the old school racers. So I cause extra clutch wear, no biggie. I'm planning on replacing stuff WAY more often then normal to get the feeling I want out of it.
So you actually want to have to change clutches and other things routinely? what fun is that?[/QUOTE]
He can use a 968 bell housing and its no big deal, just the cost of parts.
944kid, since you have a couple days stuck at home, try to get your hands on a copy of Corky Bell's Turbocharged. It breaks down most everything there is to a turbocharged engine. Also take a look at your physics book and see how stress increases with RPM (hint, its not linear). Increasing the stroke increases the piston speed, more stress. Increasing the bore increases the piston mass, more stress. On of the nice things about the Porsche engine is that its fully girdled instead of using main caps. enjoy your reading.
So you actually want to have to change clutches and other things routinely? what fun is that?[/QUOTE]
He can use a 968 bell housing and its no big deal, just the cost of parts.
944kid, since you have a couple days stuck at home, try to get your hands on a copy of Corky Bell's Turbocharged. It breaks down most everything there is to a turbocharged engine. Also take a look at your physics book and see how stress increases with RPM (hint, its not linear). Increasing the stroke increases the piston speed, more stress. Increasing the bore increases the piston mass, more stress. On of the nice things about the Porsche engine is that its fully girdled instead of using main caps. enjoy your reading.
05-05-2007, 04:01 PM
#38
Banned
Join Date: Jun 2005
Posts: 410
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by murphyslaw1978
Two identical engine with the same VE, and the larger one is going to be more powerful.
05-05-2007, 04:02 PM
#39
Banned
Join Date: Jun 2005
Posts: 410
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by JE_951
It actualy doesnt look that hard. I mean with lots of $$$ and full custom intake, exhaust, huge turbo, agressive cam, largest port/polish then it could be possible.
Because thats what you have to do to get an 4-cyl. motor to make 1000 HP.
05-05-2007, 04:12 PM
#40
Banned
Join Date: Jun 2005
Posts: 410
Likes: 0
Received 0 Likes
on
0 Posts
The common issue seems to be head lift. So besides putting in boat anchor sized head studs and putting 70000 lb. ft. of torque through them so you can run 40 lbs. of boost through a choked head why not put on a 16V head, make the engine rev out another 2000 RPM and make 600 - 700whp by virtue of mechanics rather than some insane-o cylinder pressure. You'd have less lift issues because overall cylinder pressure would be similar if not less, because the VE carries the torque band higher into the RPM.
You guys try and fight the system too much and the results are lackluster. That is why you have not made the same numbers as other 4-cyls. out there.
You guys try and fight the system too much and the results are lackluster. That is why you have not made the same numbers as other 4-cyls. out there.
05-05-2007, 05:54 PM
#41
Rennlist Lifetime Member
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Join Date: Jul 2002
Location: Northern Virginia
Posts: 2,130
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by MPD47
For once, you and I agree.
05-05-2007, 09:31 PM
#42
Rocket Scientist
Rennlist Member
Rennlist Member
I agree with Porshefile. None of your 3.0 guys take this to heart but the numbers are pathetic. And it seems that every other day another 3 liter is being built exactly the same way as the others.
Drifto- I extremely doubt the problem is only head lift. As a lifting head may contribute to clyinder shifting, it's the crap open deck design that is the real weak link. Although we will soon know for sure.
Drifto- I extremely doubt the problem is only head lift. As a lifting head may contribute to clyinder shifting, it's the crap open deck design that is the real weak link. Although we will soon know for sure.
05-05-2007, 09:35 PM
#43
Racer
Join Date: Jan 2005
Location: Central CA
Posts: 451
Likes: 0
Received 0 Likes
on
0 Posts
I think weight is the main issue with our engines.
Once Andial said when developing the GTR engine, that mass was the main problem. I wasn't so much the stuff that had to added to make it last , but what they took out to make rotating assy. lighter. He pointed out that Porsche made this engines like tractor engines, and we all know that tractor engines don't like to rev. Also oilling needs to be improve to make it durable at hi revs.
Our engines are well build.There is things that can be improve, like cylinder head, and piston design, but they have a good bore/stroke ratio, really good for high rpms. If any body have doubts about that, you only need to look at other engines with very simular ratios like ford's 5.0 V8 which many people can attest to revving to over 8k and making over500-700hp on the motor. Also V8 chevy engines are known to rev hi on race applications. Porsche own 911 GT3 engines have the almost identical Bore/stroke ratio we all know how high the turn.
Regards,
AL
Once Andial said when developing the GTR engine, that mass was the main problem. I wasn't so much the stuff that had to added to make it last , but what they took out to make rotating assy. lighter. He pointed out that Porsche made this engines like tractor engines, and we all know that tractor engines don't like to rev. Also oilling needs to be improve to make it durable at hi revs.
Our engines are well build.There is things that can be improve, like cylinder head, and piston design, but they have a good bore/stroke ratio, really good for high rpms. If any body have doubts about that, you only need to look at other engines with very simular ratios like ford's 5.0 V8 which many people can attest to revving to over 8k and making over500-700hp on the motor. Also V8 chevy engines are known to rev hi on race applications. Porsche own 911 GT3 engines have the almost identical Bore/stroke ratio we all know how high the turn.
Regards,
AL
Last edited by AL951; 05-06-2007 at 02:37 AM.
05-05-2007, 09:55 PM
#44
Nordschleife Master
Originally Posted by 944kid
What about less bore, Luke? ( & everyone else.)
No... the idea is still DISPLACEMENT. After all, it IS the oxygen that you are igniting. (not fuel).
More Bore, less stroke... means that you are 'throwing' less mass outward (over a smaller distance (i.e. stroke)). THis allows you to balance the rotating mass much easier. This means you can comfortable spin the motor faster.
Also... increased bore means more piston surface area that can be used for valves.
Originally Posted by AL951
I think weight is the main issue with our engines.
The 951 engines (i.e. heavy flywheel) is a VW/audi/Porsche trademark. They use heavier rotating masses to make a smoother feeling engine.
Originally Posted by 9fitty1
I agree with Porshefile. None of your 3.0 guys take this to heart but the numbers are pathetic.
I remember seeing a Porsche Motorsport 3.0 16v engine that you used to be able to buy from the manufacturer that made ~320-340fwhp NA. I think they were spinning it to around 9 grand.
-Luke
05-06-2007, 12:46 AM
#45
Rennlist Member
Join Date: Feb 2003
Location: Chicago
Posts: 3,526
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Luke
I remember seeing a Porsche Motorsport 3.0 16v engine that you used to be able to buy from the manufacturer that made ~320-340fwhp NA. I think they were spinning it to around 9 grand.
A 16v should kill that. The flow of a maxed out 8v turbo head is a little less than half of a maxed out 16v head. I have flowed many.