16 Valve 2.5?
05-25-2011, 03:04 PM
#46
Three Wheelin'
Thread Starter
Ok now what about the custom valve springs? Is that a one off deal and what about the TPS which one do you use the NA or the Turbo?
And is your Merkur still alive? I use to have a blast in mine, I thought it was pretty quick till I rolled on a 928 at 90 while he doing 65, I saw him down shift and he was gone!
But those were pre internet days, so mine was stock.
Yeah, that's me.And is your Merkur still alive? I use to have a blast in mine, I thought it was pretty quick till I rolled on a 928 at 90 while he doing 65, I saw him down shift and he was gone!
But those were pre internet days, so mine was stock.
05-25-2011, 03:04 PM
#47
Three Wheelin'
Stock valve springs work OK with stock rev limit and reasonable boost levels and 4valve head doesn't need high boost levels.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
My budget (and thus build time) is so big because I have throughly prepped head: stainless steel valves (from ebay, 299 usd), ceramic coating on exhaust ports and twin cam sprockets.
But that is not necessary, it will work ok with stock parts also, just don't expect it to last several hours of racing.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
My budget (and thus build time) is so big because I have throughly prepped head: stainless steel valves (from ebay, 299 usd), ceramic coating on exhaust ports and twin cam sprockets.
But that is not necessary, it will work ok with stock parts also, just don't expect it to last several hours of racing.
05-25-2011, 03:24 PM
#48
Race Car
Ok now what about the custom valve springs? Is that a one off deal and what about the TPS which one do you use the NA or the Turbo?
And is your Merkur still alive? I use to have a blast in mine, I thought it was pretty quick till I rolled on a 928 at 90 while he doing 65, I saw him down shift and he was gone! But those were pre internet days, so mine was stock.
And is your Merkur still alive? I use to have a blast in mine, I thought it was pretty quick till I rolled on a 928 at 90 while he doing 65, I saw him down shift and he was gone!
But those were pre internet days, so mine was stock.Not sure where to get the springs, but I imagine they are available. I'm not there, yet.
Stock valve springs work OK with stock rev limit and reasonable boost levels and 4valve head doesn't need high boost levels.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
I said that stock cams would not be ideal. (!! - ?) They will "work," but how well they work is subjective. If you read through and look at Chris' pictures, you'll see that he gets around it by running the belt around both cams, which is presumably to separate the timing between the two a little more. I was suggesting a regrind with the purpose of changing the timing of the cams relative to each other in lieu of that. LSA = lobe separation angle. Similar to overlap. The stock S cam gives you a 111 degree LSA. Having driven a turbocharged car with that for a few years, it was not very streetable.
05-25-2011, 03:29 PM
#49
Nordschleife Master
Aww dude you were there! Well I am an audiophile also so I gotta go with the Noise! Street car would be my goal would this have a streetable power band, 3000 and up or would it be a 4000 rpm up motor?
Cause my current steed is already pretty pissy about 55 mph in 4th gear let alone 5th! Wouldn't want it to be any worse!
And yes I think I get it do the liter and the lower end sucks up dollars, do the 16 valve head and the top end sucks up dollars!
Cause my current steed is already pretty pissy about 55 mph in 4th gear let alone 5th! Wouldn't want it to be any worse!
And yes I think I get it do the liter and the lower end sucks up dollars, do the 16 valve head and the top end sucks up dollars!
Good luck, it CAN be accomplished, and for a street car can last.. (FWIW, Wormholes engine I believe is in its second season, without issue!)
If you are an Audiophile, than make it sound good, and be happy with a stock motor.. its can be plenty fast enough...
05-25-2011, 03:29 PM
#50
Three Wheelin'
Thread Starter
Stock valve springs work OK with stock rev limit and reasonable boost levels and 4valve head doesn't need high boost levels.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
My budget (and thus build time) is so big because I have throughly prepped head: stainless steel valves (from ebay, 299 usd), ceramic coating on exhaust ports and twin cam sprockets.
But that is not necessary, it will work ok with stock parts also, just don't expect it to last several hours of racing.
For street engine stock valves work also OK and why anyone says that stock cams won't work?? There isn't any grounds on that statement.
Markus951 built his 968 turbo on entirely stock package sans 951 rods and thicker MLS head gasket. Result? 500 rwhp @ just 1.3 bars of boost. With stock valves, springs and cams.
My budget (and thus build time) is so big because I have throughly prepped head: stainless steel valves (from ebay, 299 usd), ceramic coating on exhaust ports and twin cam sprockets.
But that is not necessary, it will work ok with stock parts also, just don't expect it to last several hours of racing.
05-25-2011, 04:52 PM
#51
Three Wheelin'
If one uses two exhaust cams and implements twin adjustable sprockets, stock cams will be more than adequate.
And Markus951 engine used stock single cam drive and lobe separation, no issues and the engine had lots of torque down low. There is a dyno plot also in his thread.
schip43, on turbocharged car low end torque depends mostly on turbocharger choice but I definitely wouldn't choke the well-flowing head of 944S with ultra-small turbine. good choice is Holset HX35 with #12 turbine. That will give you full boost around 3000 rpm and positive manifold pressure around 2000 rpm. Max hp will be around 500.
Just for reference, I use HX40 Super with #16 turbine on my build but I don't expect full boost until 4000 rpm. If I want low end torque, I can drive my A8 4.2 V8.
And Markus951 engine used stock single cam drive and lobe separation, no issues and the engine had lots of torque down low. There is a dyno plot also in his thread.
schip43, on turbocharged car low end torque depends mostly on turbocharger choice but I definitely wouldn't choke the well-flowing head of 944S with ultra-small turbine. good choice is Holset HX35 with #12 turbine. That will give you full boost around 3000 rpm and positive manifold pressure around 2000 rpm. Max hp will be around 500.
Just for reference, I use HX40 Super with #16 turbine on my build but I don't expect full boost until 4000 rpm. If I want low end torque, I can drive my A8 4.2 V8.
05-25-2011, 05:00 PM
#52
Three Wheelin'
Thread Starter
If one uses two exhaust cams and implements twin adjustable sprockets, stock cams will be more than adequate.
And Markus951 engine used stock single cam drive and lobe separation, no issues and the engine had lots of torque down low. There is a dyno plot also in his thread.
schip43, on turbocharged car low end torque depends mostly on turbocharger choice but I definitely wouldn't choke the well-flowing head of 944S with ultra-small turbine. good choice is Holset HX35 with #12 turbine. That will give you full boost around 3000 rpm and positive manifold pressure around 2000 rpm. Max hp will be around 500.
Just for reference, I use HX40 Super with #16 turbine on my build but I don't expect full boost until 4000 rpm. If I want low end torque, I can drive my A8 4.2 V8.
And Markus951 engine used stock single cam drive and lobe separation, no issues and the engine had lots of torque down low. There is a dyno plot also in his thread.
schip43, on turbocharged car low end torque depends mostly on turbocharger choice but I definitely wouldn't choke the well-flowing head of 944S with ultra-small turbine. good choice is Holset HX35 with #12 turbine. That will give you full boost around 3000 rpm and positive manifold pressure around 2000 rpm. Max hp will be around 500.
Just for reference, I use HX40 Super with #16 turbine on my build but I don't expect full boost until 4000 rpm. If I want low end torque, I can drive my A8 4.2 V8.
05-25-2011, 05:10 PM
#53
Three Wheelin'
Thread Starter
Nope, parted it out, then junked it. It was too far gone with rust. I had been building a 2.5L stroker when I had my first kids. By the time I got working on it again, the rust was too much. I had done a lot of porting work, and all fo the bolt ons, plus a MAF conversion a friend and I did that was similar to Rogue's, though we used the Ford method of calculating load tables from MAF values, rather than a MAP. I was moving 33#/min of air with the stock T3, which was at the absolute limit of that turbo. Had a friend who was into drag racing tell me he thought it was a 12 second car.
Not sure where to get the springs, but I imagine they are available. I'm not there, yet.
First of all, why build a turbocharged 4V if you aren't going to blow on it? So yeah, when you've got 100# springs, adding an extra 30# on top of it significantly reduces its ability to close the valve. Probably double that increase on the exhaust side. That's why I suggested stiffer springs.
I said that stock cams would not be ideal. (!! - ?) They will "work," but how well they work is subjective. If you read through and look at Chris' pictures, you'll see that he gets around it by running the belt around both cams, which is presumably to separate the timing between the two a little more. I was suggesting a regrind with the purpose of changing the timing of the cams relative to each other in lieu of that. LSA = lobe separation angle. Similar to overlap. The stock S cam gives you a 111 degree LSA. Having driven a turbocharged car with that for a few years, it was not very streetable.
First of all, why build a turbocharged 4V if you aren't going to blow on it? So yeah, when you've got 100# springs, adding an extra 30# on top of it significantly reduces its ability to close the valve. Probably double that increase on the exhaust side. That's why I suggested stiffer springs.
I said that stock cams would not be ideal. (!! - ?) They will "work," but how well they work is subjective. If you read through and look at Chris' pictures, you'll see that he gets around it by running the belt around both cams, which is presumably to separate the timing between the two a little more. I was suggesting a regrind with the purpose of changing the timing of the cams relative to each other in lieu of that. LSA = lobe separation angle. Similar to overlap. The stock S cam gives you a 111 degree LSA. Having driven a turbocharged car with that for a few years, it was not very streetable.
Oh I see so the twin gear deals is about more than it looks cool! LSA or regrind for a new LSA instead of twin gear conversion and sawsall on the hood!
05-25-2011, 05:18 PM
#54
Three Wheelin'
Thread Starter
Wow harsh but true that!
Wait is Wormhole a Lister? I though it was a description of where the cash would be going!
Naw, just exploring the options, my car is already pretty fast! I keep a post card with the penalty for felony speeding on the dash!
05-25-2011, 07:07 PM
#55
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Geez, I go out to the shop to work and you guys just chat all day!
Here are some replies -
The 8v pistons will work but the bowl shape is not optimized for the shape of the 16v combustion chamber. For the 104mm bores you can get away without a valve relief but with the 100mm bore the valves are getting very close to the edge of the pistons – where there is no bowl.
The stock springs have a very low seat pressure, not good for a turbo motor. The springs I use a quite a bit lighter in weight and have about 30lbs more seat pressure. Not a huge change, the other feature is that they are new – not 25 years old. I can set the head up correctly because I don’t have to shim all the valves to make up for lost pressure.
Valves – EGTs can get pretty high on turbos when they are run with over rich mixtures and reduced timing. Its good to have a higher temp alloy.
The torque curve on that engine did not drop off at all up to 6800. Looks like it would be still flat to 7500! If I recall correctly the HP was just under 500 to the wheels, if we ran it to 7500 it would have picked up another 50hp!
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
Here are some replies -
"custom pistons valves and valve springs "
I don't get it chris ..
at full lift the valves are only protruding about 2-3mm from the head (2.5/16v)
and at a guess that it's no where near TDC
so although its nice in the case of a belt failure surly it can run without valve reliefs ??? therefor ruglar 944 turbo pistons ?
and customs valves and springs why ?
also wouldn't the knock resistant nature of the 16v head make the increased compratio yielded with smaller head cc ok ?
I don't get it chris ..
at full lift the valves are only protruding about 2-3mm from the head (2.5/16v)
and at a guess that it's no where near TDC
so although its nice in the case of a belt failure surly it can run without valve reliefs ??? therefor ruglar 944 turbo pistons ?
and customs valves and springs why ?
also wouldn't the knock resistant nature of the 16v head make the increased compratio yielded with smaller head cc ok ?
The stock springs have a very low seat pressure, not good for a turbo motor. The springs I use a quite a bit lighter in weight and have about 30lbs more seat pressure. Not a huge change, the other feature is that they are new – not 25 years old. I can set the head up correctly because I don’t have to shim all the valves to make up for lost pressure.
Valves – EGTs can get pretty high on turbos when they are run with over rich mixtures and reduced timing. Its good to have a higher temp alloy.
Well, this thread is very interesting. I happen to have a 16V 2.5L and have been wondering about this for some time. It is also just another one of my many "plans to complete" and may never go further than reading this thread.
I have compared the intake and exhaust cams for the dual pulley setup and there is not a bunch of difference, I read the specs at some point in the past, but can't recall them now. Is there any information available about the front pulley setup and part numbers for pulley and TB?
Chris, what did the dyno results look like compared to a similarly built 8v?
I have compared the intake and exhaust cams for the dual pulley setup and there is not a bunch of difference, I read the specs at some point in the past, but can't recall them now. Is there any information available about the front pulley setup and part numbers for pulley and TB?
Chris, what did the dyno results look like compared to a similarly built 8v?
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
05-25-2011, 08:27 PM
#56
Three Wheelin'
Thread Starter
Geez, I go out to the shop to work and you guys just chat all day!
Here are some replies -
The 8v pistons will work but the bowl shape is not optimized for the shape of the 16v combustion chamber. For the 104mm bores you can get away without a valve relief but with the 100mm bore the valves are getting very close to the edge of the pistons – where there is no bowl.
The stock springs have a very low seat pressure, not good for a turbo motor. The springs I use a quite a bit lighter in weight and have about 30lbs more seat pressure. Not a huge change, the other feature is that they are new – not 25 years old. I can set the head up correctly because I don’t have to shim all the valves to make up for lost pressure.
Valves – EGTs can get pretty high on turbos when they are run with over rich mixtures and reduced timing. Its good to have a higher temp alloy.
The torque curve on that engine did not drop off at all up to 6800. Looks like it would be still flat to 7500! If I recall correctly the HP was just under 500 to the wheels, if we ran it to 7500 it would have picked up another 50hp!
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
Here are some replies -
The 8v pistons will work but the bowl shape is not optimized for the shape of the 16v combustion chamber. For the 104mm bores you can get away without a valve relief but with the 100mm bore the valves are getting very close to the edge of the pistons – where there is no bowl.
The stock springs have a very low seat pressure, not good for a turbo motor. The springs I use a quite a bit lighter in weight and have about 30lbs more seat pressure. Not a huge change, the other feature is that they are new – not 25 years old. I can set the head up correctly because I don’t have to shim all the valves to make up for lost pressure.
Valves – EGTs can get pretty high on turbos when they are run with over rich mixtures and reduced timing. Its good to have a higher temp alloy.
The torque curve on that engine did not drop off at all up to 6800. Looks like it would be still flat to 7500! If I recall correctly the HP was just under 500 to the wheels, if we ran it to 7500 it would have picked up another 50hp!
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
Valves and springs is that something you carry in stock or can get? Or better still, would know what the hell I'd be asking about!
Is this combo a viable street motor? I understand it's not necessary! The manifold reworking is a given. Reworking the cams (LSA) in order to avoid CTH (cutting the hood)is a given. Is a standalone really necessary? I'm thinking Rouge's setup would work?
What combo would you suggest for a streetable 2.5 16v motor and what is the HP potential?
And is that beast still alive and does it wail like that in the real world?
05-25-2011, 09:09 PM
#57
Burning Brakes
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Geez, I go out to the shop to work and you guys just chat all day!
Here are some replies -
The torque curve on that engine did not drop off at all up to 6800. Looks like it would be still flat to 7500! If I recall correctly the HP was just under 500 to the wheels, if we ran it to 7500 it would have picked up another 50hp!
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
Here are some replies -
The torque curve on that engine did not drop off at all up to 6800. Looks like it would be still flat to 7500! If I recall correctly the HP was just under 500 to the wheels, if we ran it to 7500 it would have picked up another 50hp!
The dual cam drive is a little trickier than it seems. You cannot run two stock gears because the diameter is too big. I use smaller gears and as a result I have to make up a custom crank driver gear.
The stock set up is not too bad as is – but if you want better midrange torque you need to change the LSA and do some other little tweaks.
I have always love the sound of the 4V since I owned my first 944S many years ago. That dyno video clip sounds awesome.
I know that the lifters are still probably the limiting factor on the 4V head. Do you use solid lifters or do you feel 7500 is safe with the increased pressure of the custom springs you use? At this point in life, if I did start the build (in my head) it would be for street use and I would love to have my day start off and end with that wonderful sound.
Again, thanks for sharing.
05-25-2011, 10:35 PM
#58
Three Wheelin'
Thread Starter
Chris, Thanks for the reply. I knew there was more to the twin cam drive belt, just wondering if the parts were available "off the shelf". Guess it depends on who's shelf they are off of.
I have always love the sound of the 4V since I owned my first 944S many years ago. That dyno video clip sounds awesome.
I know that the lifters are still probably the limiting factor on the 4V head. Do you use solid lifters or do you feel 7500 is safe with the increased pressure of the custom springs you use? At this point in life, if I did start the build (in my head) it would be for street use and I would love to have my day start off and end with that wonderful sound.
Again, thanks for sharing.
I have always love the sound of the 4V since I owned my first 944S many years ago. That dyno video clip sounds awesome.
I know that the lifters are still probably the limiting factor on the 4V head. Do you use solid lifters or do you feel 7500 is safe with the increased pressure of the custom springs you use? At this point in life, if I did start the build (in my head) it would be for street use and I would love to have my day start off and end with that wonderful sound.
Again, thanks for sharing.
05-26-2011, 03:01 AM
#59
Three Wheelin'
All I can say that many things that are far from optimum still work OK! Just don't expect it to last for several hour race!
I remember there was a common understanding that stock 924 2.0 engine is too weak for any power (and still is I suppose) but I turbocharged stock euro 924 engine and got 250 hp/320 Nm that was reliable (driven it for 4 years and occasional track time also).
Is it optimal and best of the best solution? No. Does it work, has fun factor and lasts? YES!
I remember there was a common understanding that stock 924 2.0 engine is too weak for any power (and still is I suppose) but I turbocharged stock euro 924 engine and got 250 hp/320 Nm that was reliable (driven it for 4 years and occasional track time also).
Is it optimal and best of the best solution? No. Does it work, has fun factor and lasts? YES!
05-26-2011, 05:48 AM
#60
Nordschleife Master
I'm glad there's people who take another approach, and the few that do that tend to end up with some very good results.