16 Valve 2.5?
05-24-2011, 11:38 AM
#1
Three Wheelin'
Thread Starter
16 Valve 2.5?
Is this a viable option for a 2.5? Can it be done at a reasonable cost and is it worth doing? I don't recall seeing this done?
Just wondering because these days the big numbers seem to be done with motors (4 cylinders) that are 500 cc smaller than ours but have 16 valve heads.
For that matter the Subbies (STI) are 2.5 16 valve heads.
Just wondering if it's something worth pursuing?
Just wondering because these days the big numbers seem to be done with motors (4 cylinders) that are 500 cc smaller than ours but have 16 valve heads.
For that matter the Subbies (STI) are 2.5 16 valve heads.
Just wondering if it's something worth pursuing?
05-24-2011, 11:51 AM
#2
Race Car
Definitely has been done. Chris White has pistons available. There is another lister that is doing it now by flycutting the stock pistons.
I want to do it but have to wait until I can get to a better financial position.
I want to do it but have to wait until I can get to a better financial position.
05-24-2011, 11:52 AM
#3
Professional Hoon
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I think Chris White is working on a 2.6 16v or finished. cannot remember but it's in his PM.
I wouldn't mind doing it my self but then i always just think 3L
I wouldn't mind doing it my self but then i always just think 3L
05-24-2011, 12:11 PM
#4
Burning Brakes
it's not worth it. There's more power but not enough to justify the expense or aggravation.
I own an S, and I own a turbo. Would make more sense to get a wrecked turbo and convert than a wrecked 16V car and convert.
I own an S, and I own a turbo. Would make more sense to get a wrecked turbo and convert than a wrecked 16V car and convert.
05-24-2011, 12:29 PM
#5
Three Wheelin'
Thread Starter
You got any links to the builds on here?
05-24-2011, 12:42 PM
#6
Race Car
To be clear, we are talking about a turbocharged 2.5l 16v engine correct prettybird? I can't see how it would not be beneficial unless you are just after a 300 hp car, then I could see the tq of tge 8v being better.
05-24-2011, 01:06 PM
#7
Nordschleife Master
Take a turbo motor, add head and pistons from Chris White (he HAS all the bits needed in his shop RIGHT NOW), and you are off... just takes several metric loads of $$ (IIRC the heads are worth about 1K, pistons about the same, stand alone ~3K, intake and exhaust another 3-4K depending on options.. full engine rebuild with proper bits going in to support the bigger power ~3-5K)
He has done at least one or two of them, required bits IMHO would be stand alone, higher volume fuel system, and the required bits being custom intake and exhaust (Speed Force Racing offers these bits, but be prepared for sticker shock..even though they are well worth it)..
IIRC 2.5L 8V is at its limits about 400 HP, 2.5 16V is about there at 500rwhp..
Either way, to maximize the usefullness you will need other supporting mods to accomplish this... it deffinitely isn't bolt in, however the supporting mods (including the intake and exhaust) can convey over to a 3L 16V motor quite nicely!
However be prepared to spend between 10 and 15K to get there, and you will still have a 2.5L displacement... same money can get a decent 3L... without supporting mods to the chasis..
Dont forget brakes, induction cooling system, exhaust, turbo, suspension... should I continue?
He has done at least one or two of them, required bits IMHO would be stand alone, higher volume fuel system, and the required bits being custom intake and exhaust (Speed Force Racing offers these bits, but be prepared for sticker shock..even though they are well worth it)..
IIRC 2.5L 8V is at its limits about 400 HP, 2.5 16V is about there at 500rwhp..
Either way, to maximize the usefullness you will need other supporting mods to accomplish this... it deffinitely isn't bolt in, however the supporting mods (including the intake and exhaust) can convey over to a 3L 16V motor quite nicely!
However be prepared to spend between 10 and 15K to get there, and you will still have a 2.5L displacement... same money can get a decent 3L... without supporting mods to the chasis..
Dont forget brakes, induction cooling system, exhaust, turbo, suspension... should I continue?
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05-24-2011, 01:56 PM
#8
Race Car
Horsepower is a function of airflow. Airflow is a function of valve area available for airflow. A stock head has a single 45mm intake valve. A 16V has two 37mm valves (the 968 has two 39mm valves). That is 35% more airflow area. A well built 2.5L 16V has a lot more horsepower potential, if less torque potential, than an 8V 3.0L, unless the 3.0L has had a lot of head work done. A LOT.
The pent roof chamber and central plug allows you to run about 0.7 points more CR with the same level of detonation robustness, ceteris paribus. A bigger bore hurts your ability to run more CR. That'll get you another 3-4% torque and power across the board.
The head has to come off of a 2.5L (i.e. a 944S), I believe (I believe the water passages are different on the 104mm bore engines). I don't know what valve material they are, but if they are not one piece stainless, you'd be wise to get that. That's probably $300.
I had a conversation with Karl Poeltl of Racer's Edge, who is the NA distributor for Wossner pistons, late last week about this. They sell a lot of these pistons, so folks who spend more time in their garage than on Rennlist are apparently doing this. A set is right around $1000. I'm friends with Karl, and he is local to me, so I'd go with him, but there's no doubt Chris White would do you right, too.
Then you need to fab an intake. And cutting up a turbo intake and welding it to an S flange is not fabbing an intake, you are just choking off all of that valve area you just gained by doing a 16V. If you've got a TIG and can weld aluminum, figure a couple hundred bucks for bellmounths (Acura sells them for their V6's, which is a good affordable option, but I can't recall how big they are) and stock aluminum. If not, figure probably $500 or so for someone else to fab it up.
Figure new rings at $400.
You are probably looking at $2000 to do it, assuming you can do it all yourself, and have the 16V head (throw in another $500 or so if you don't). And that is before you get into the bigger turbo and controls systems.
The pent roof chamber and central plug allows you to run about 0.7 points more CR with the same level of detonation robustness, ceteris paribus. A bigger bore hurts your ability to run more CR. That'll get you another 3-4% torque and power across the board.
The head has to come off of a 2.5L (i.e. a 944S), I believe (I believe the water passages are different on the 104mm bore engines). I don't know what valve material they are, but if they are not one piece stainless, you'd be wise to get that. That's probably $300.
I had a conversation with Karl Poeltl of Racer's Edge, who is the NA distributor for Wossner pistons, late last week about this. They sell a lot of these pistons, so folks who spend more time in their garage than on Rennlist are apparently doing this. A set is right around $1000. I'm friends with Karl, and he is local to me, so I'd go with him, but there's no doubt Chris White would do you right, too.
Then you need to fab an intake. And cutting up a turbo intake and welding it to an S flange is not fabbing an intake, you are just choking off all of that valve area you just gained by doing a 16V. If you've got a TIG and can weld aluminum, figure a couple hundred bucks for bellmounths (Acura sells them for their V6's, which is a good affordable option, but I can't recall how big they are) and stock aluminum. If not, figure probably $500 or so for someone else to fab it up.
Figure new rings at $400.
You are probably looking at $2000 to do it, assuming you can do it all yourself, and have the 16V head (throw in another $500 or so if you don't). And that is before you get into the bigger turbo and controls systems.
05-24-2011, 02:08 PM
#9
Three Wheelin'
Thread Starter
And yeah in the 60 to 150 mph range mine is a runner, I've had to do a beat down that required 60 to 90 and at 90 I was gone! Not a fan of tail gaters!
05-24-2011, 02:25 PM
#10
Professional Hoon
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the STIs need over 20 psi to go anywhere. i had a roll race with one when i first had my 951 running 15 psi with a 100% stock exhaust and he had 15 psi 3" and a few other minor things. and i literly blew his doors off. he had more of a responce but still not as much torque.
Just by a quick read that you do need to change the pistons might aswel go S2 block and start there and get more power for less boost.
Just by a quick read that you do need to change the pistons might aswel go S2 block and start there and get more power for less boost.
05-24-2011, 02:34 PM
#11
Three Wheelin'
Thread Starter
Take a turbo motor, add head and pistons from Chris White (he HAS all the bits needed in his shop RIGHT NOW), and you are off... just takes several metric loads of $$ (IIRC the heads are worth about 1K, pistons about the same, stand alone ~3K, intake and exhaust another 3-4K depending on options.. full engine rebuild with proper bits going in to support the bigger power ~3-5K)
He has done at least one or two of them, required bits IMHO would be stand alone, higher volume fuel system, and the required bits being custom intake and exhaust (Speed Force Racing offers these bits, but be prepared for sticker shock..even though they are well worth it)..
IIRC 2.5L 8V is at its limits about 400 HP, 2.5 16V is about there at 500rwhp..
Either way, to maximize the usefullness you will need other supporting mods to accomplish this... it deffinitely isn't bolt in, however the supporting mods (including the intake and exhaust) can convey over to a 3L 16V motor quite nicely!
However be prepared to spend between 10 and 15K to get there, and you will still have a 2.5L displacement... same money can get a decent 3L... without supporting mods to the chasis..
Dont forget brakes, induction cooling system, exhaust, turbo, suspension... should I continue?
He has done at least one or two of them, required bits IMHO would be stand alone, higher volume fuel system, and the required bits being custom intake and exhaust (Speed Force Racing offers these bits, but be prepared for sticker shock..even though they are well worth it)..
IIRC 2.5L 8V is at its limits about 400 HP, 2.5 16V is about there at 500rwhp..
Either way, to maximize the usefullness you will need other supporting mods to accomplish this... it deffinitely isn't bolt in, however the supporting mods (including the intake and exhaust) can convey over to a 3L 16V motor quite nicely!
However be prepared to spend between 10 and 15K to get there, and you will still have a 2.5L displacement... same money can get a decent 3L... without supporting mods to the chasis..
Dont forget brakes, induction cooling system, exhaust, turbo, suspension... should I continue?
Horsepower is a function of airflow. Airflow is a function of valve area available for airflow. A stock head has a single 45mm intake valve. A 16V has two 37mm valves (the 968 has two 39mm valves). That is 35% more airflow area. A well built 2.5L 16V has a lot more horsepower potential, if less torque potential, than an 8V 3.0L, unless the 3.0L has had a lot of head work done. A LOT.
The pent roof chamber and central plug allows you to run about 0.7 points more CR with the same level of detonation robustness, ceteris paribus. A bigger bore hurts your ability to run more CR. That'll get you another 3-4% torque and power across the board.
The head has to come off of a 2.5L (i.e. a 944S), I believe (I believe the water passages are different on the 104mm bore engines). I don't know what valve material they are, but if they are not one piece stainless, you'd be wise to get that. That's probably $300.
I had a conversation with Karl Poeltl of Racer's Edge, who is the NA distributor for Wossner pistons, late last week about this. They sell a lot of these pistons, so folks who spend more time in their garage than on Rennlist are apparently doing this. A set is right around $1000. I'm friends with Karl, and he is local to me, so I'd go with him, but there's no doubt Chris White would do you right, too.
Then you need to fab an intake. And cutting up a turbo intake and welding it to an S flange is not fabbing an intake, you are just choking off all of that valve area you just gained by doing a 16V. If you've got a TIG and can weld aluminum, figure a couple hundred bucks for bellmounths (Acura sells them for their V6's, which is a good affordable option, but I can't recall how big they are) and stock aluminum. If not, figure probably $500 or so for someone else to fab it up.
Figure new rings at $400.
You are probably looking at $2000 to do it, assuming you can do it all yourself, and have the 16V head (throw in another $500 or so if you don't). And that is before you get into the bigger turbo and controls systems.
The pent roof chamber and central plug allows you to run about 0.7 points more CR with the same level of detonation robustness, ceteris paribus. A bigger bore hurts your ability to run more CR. That'll get you another 3-4% torque and power across the board.
The head has to come off of a 2.5L (i.e. a 944S), I believe (I believe the water passages are different on the 104mm bore engines). I don't know what valve material they are, but if they are not one piece stainless, you'd be wise to get that. That's probably $300.
I had a conversation with Karl Poeltl of Racer's Edge, who is the NA distributor for Wossner pistons, late last week about this. They sell a lot of these pistons, so folks who spend more time in their garage than on Rennlist are apparently doing this. A set is right around $1000. I'm friends with Karl, and he is local to me, so I'd go with him, but there's no doubt Chris White would do you right, too.
Then you need to fab an intake. And cutting up a turbo intake and welding it to an S flange is not fabbing an intake, you are just choking off all of that valve area you just gained by doing a 16V. If you've got a TIG and can weld aluminum, figure a couple hundred bucks for bellmounths (Acura sells them for their V6's, which is a good affordable option, but I can't recall how big they are) and stock aluminum. If not, figure probably $500 or so for someone else to fab it up.
Figure new rings at $400.
You are probably looking at $2000 to do it, assuming you can do it all yourself, and have the 16V head (throw in another $500 or so if you don't). And that is before you get into the bigger turbo and controls systems.
But OK the good news is a 500 hp vs 400 but then a 3 liter is 500 hp potential also? So is it the same cost for a 3L short block (8 valve head) vs a 16 valve head with a 2.5 block?
Yeah I'm not a welder ( and yeah I'm on the internet and not in the garage!
) so I'd have to get the manifolds done just wondering about the potential and viability streetability of this combo. Would it be any more or less useless in 4th at 55 and low rpm or the same as I have now just even crazier when it gets on boost?
05-24-2011, 02:57 PM
#12
Burning Brakes
redline goes up by a few hundred RPM.
I was talking NA, but the expense parts still applies to a turbo car... vMax goes up but at a hell of a price.
05-24-2011, 03:51 PM
#13
Three Wheelin'
Thread Starter
the STIs need over 20 psi to go anywhere. i had a roll race with one when i first had my 951 running 15 psi with a 100% stock exhaust and he had 15 psi 3" and a few other minor things. and i literly blew his doors off. he had more of a responce but still not as much torque.
Just by a quick read that you do need to change the pistons might aswel go S2 block and start there and get more power for less boost.
Just by a quick read that you do need to change the pistons might aswel go S2 block and start there and get more power for less boost.
I just used it as an example (STI) because it's a multi valve head and a 2.5. Yeah in a roll on 8 valve 2.5 does very well, just wondering about the head. The S2 is the 3 liter DOHC correct? So I see your point, since it would take custom manifolds anyway! But even granted that these are Porsches ( Poor Red headed step children, they my be but still Porsches) and not Honda's it can't be the same cost for putting a 16 valve head on a 2.5 as building a 3.0?
I ask that because I know most of the 3 liter builds use the 8 valve head! Kinda of a big circle here?
