5.0L track motor build is finally done!
05-12-2008, 04:05 PM
#61
Nordschleife Master
Actually the stock retainers are pretty damn heavy. Last time i felt a Ti Retainer was years ago but i wouldnt be surprised if the weight difference was a gram or 2. I wouln't be surprised if the steel retainer is 3-4x the weight of the Ti. But this is all from a long time ago, i dont really remember, but i do know the stock retainers arent exactly light.
Add Ti retainers to lighter lifters and you can run lighter springs which will require less HP (or parasitic loss) to drive 4 cams and the difference could be noticeable. Again, without weights of stock vs Ti or lighter lifters the point is null. But valve train weight is very critical.
Add Ti retainers to lighter lifters and you can run lighter springs which will require less HP (or parasitic loss) to drive 4 cams and the difference could be noticeable. Again, without weights of stock vs Ti or lighter lifters the point is null. But valve train weight is very critical.
05-12-2008, 04:59 PM
#62
Rennlist Member
I think i said exactly that. 
So, in otherwords, if you aint driving the engine up to 7k plus, its a non issue for our cars.
mk
So, in otherwords, if you aint driving the engine up to 7k plus, its a non issue for our cars.
mk
05-12-2008, 05:06 PM
#63
Rennlist Member
Sure, the Ti retainers are a lot lighter, but 1-2 grams is nothing compared to the 20+ grams savings of the lighter 48gram lifter (70grams stock), and that, in itself, is nothing as a value of saving any HP. (i.e. 1 ounce per lifter)
what it would do, is allow more strength for a given thickness and thats what they use them for. (as they have to hold the top of the valve stem with a little clip) both the valve stem can break, and does, or the retainer ring can distort and let the valve with its little clip through. so, my point is that the 1oz lighter lifter is not going to make any HP difference, and certainly 1-2 grams would be 1/24th of that.
sure a light valve train is important, but as DrBob just reiterated, its really usefull for real high rpms, and the valves are important as well.
valves, lifters, and to a lesser extent the retainer rings all equal valve train weight. rpms and spring force will then determine what the HP savings might be. the main reason to use these lighter components is to be able to use a lighter spring, and that isnt being done in our discussions.
mk
what it would do, is allow more strength for a given thickness and thats what they use them for. (as they have to hold the top of the valve stem with a little clip) both the valve stem can break, and does, or the retainer ring can distort and let the valve with its little clip through. so, my point is that the 1oz lighter lifter is not going to make any HP difference, and certainly 1-2 grams would be 1/24th of that.
sure a light valve train is important, but as DrBob just reiterated, its really usefull for real high rpms, and the valves are important as well.
valves, lifters, and to a lesser extent the retainer rings all equal valve train weight. rpms and spring force will then determine what the HP savings might be. the main reason to use these lighter components is to be able to use a lighter spring, and that isnt being done in our discussions.
mk
Actually the stock retainers are pretty damn heavy. Last time i felt a Ti Retainer was years ago but i wouldnt be surprised if the weight difference was a gram or 2. I wouln't be surprised if the steel retainer is 3-4x the weight of the Ti. But this is all from a long time ago, i dont really remember, but i do know the stock retainers arent exactly light.
Add Ti retainers to lighter lifters and you can run lighter springs which will require less HP (or parasitic loss) to drive 4 cams and the difference could be noticeable. Again, without weights of stock vs Ti or lighter lifters the point is null. But valve train weight is very critical.
Add Ti retainers to lighter lifters and you can run lighter springs which will require less HP (or parasitic loss) to drive 4 cams and the difference could be noticeable. Again, without weights of stock vs Ti or lighter lifters the point is null. But valve train weight is very critical.
Last edited by mark kibort; 05-12-2008 at 07:33 PM.
05-13-2008, 02:13 AM
#64
Three Wheelin'
Join Date: Jan 2007
Location: not where you think I am
Posts: 1,466
Likes: 0
Received 0 Likes
on
0 Posts
titanium retainers/valves are for higher rpms.
high rpm valve springs are not lighter. the pressures actually increase to keep the valve/lifter from floating. most high lift cam kits use a stiffer single spring---all the way up to triple spring sets (roller cams and such).
it's all about returning the valve to it's seat after opening. the higher the lift/rpms, the faster you need the valve to close.
valve train weight loss does help, but pretty much not necessary until above 7000 rpms.....We've run stock valve train components in NHRA stock class racing for season after season, at 7000 rpms, without issue. No titanium parts, as they are not allowed.....
928 engines should be no different as long as the parts are in good condition and installed according to manufacturer's specs.....
if you are running twenty year old valve springs in your race motor, you're probably asking for trouble, regardless of 6 grand or 8.
-R
high rpm valve springs are not lighter. the pressures actually increase to keep the valve/lifter from floating. most high lift cam kits use a stiffer single spring---all the way up to triple spring sets (roller cams and such).
it's all about returning the valve to it's seat after opening. the higher the lift/rpms, the faster you need the valve to close.
valve train weight loss does help, but pretty much not necessary until above 7000 rpms.....We've run stock valve train components in NHRA stock class racing for season after season, at 7000 rpms, without issue. No titanium parts, as they are not allowed.....
928 engines should be no different as long as the parts are in good condition and installed according to manufacturer's specs.....
if you are running twenty year old valve springs in your race motor, you're probably asking for trouble, regardless of 6 grand or 8.
-R
05-13-2008, 01:32 PM
#65
Rennlist Member
again, I was only making the point that the lighter weight components dont do anything as far as HP and are only for reducing valve float at high rpms. in theory, if you wanted to have some (probably imeasurable) gains, you could use a lighter spring with the same valve train weight, except lighter lifters and reduce some friction. but, in the end, you are absolutely right. the lighter components are not a power gaining (saving)deal. they are to protect the valve stem (when made of Ti), they are to keep the valve from floating at high rpms (lighter lifter or lighter valve) and to keep from dropping valves (Ti retaining ring) by not having the retaining ring break and release the valve under high rpms.
As far as my 21 year old engine and its 21 year old valve springs. its seems to be working fine, and i dont expect any issues, even if one got soft, as what is the worst that can happen, loss of power at High rpms? (ie 6.6k) so far, no issues. (knock knock). I do think the double spring is tough, and is more of a mileage thing, or maybe even total compressions. (total rpms). if that was the case, i still dont worry too much about this. remember, i had a part euro motor, with stock valve springs that are now 26 years old and its still running fine.
mk
(
As far as my 21 year old engine and its 21 year old valve springs. its seems to be working fine, and i dont expect any issues, even if one got soft, as what is the worst that can happen, loss of power at High rpms? (ie 6.6k) so far, no issues. (knock knock). I do think the double spring is tough, and is more of a mileage thing, or maybe even total compressions. (total rpms). if that was the case, i still dont worry too much about this. remember, i had a part euro motor, with stock valve springs that are now 26 years old and its still running fine.
mk
(
titanium retainers/valves are for higher rpms.
high rpm valve springs are not lighter. the pressures actually increase to keep the valve/lifter from floating. most high lift cam kits use a stiffer single spring---all the way up to triple spring sets (roller cams and such).
it's all about returning the valve to it's seat after opening. the higher the lift/rpms, the faster you need the valve to close.
valve train weight loss does help, but pretty much not necessary until above 7000 rpms.....We've run stock valve train components in NHRA stock class racing for season after season, at 7000 rpms, without issue. No titanium parts, as they are not allowed.....
928 engines should be no different as long as the parts are in good condition and installed according to manufacturer's specs.....
if you are running twenty year old valve springs in your race motor, you're probably asking for trouble, regardless of 6 grand or 8.
-R
high rpm valve springs are not lighter. the pressures actually increase to keep the valve/lifter from floating. most high lift cam kits use a stiffer single spring---all the way up to triple spring sets (roller cams and such).
it's all about returning the valve to it's seat after opening. the higher the lift/rpms, the faster you need the valve to close.
valve train weight loss does help, but pretty much not necessary until above 7000 rpms.....We've run stock valve train components in NHRA stock class racing for season after season, at 7000 rpms, without issue. No titanium parts, as they are not allowed.....
928 engines should be no different as long as the parts are in good condition and installed according to manufacturer's specs.....
if you are running twenty year old valve springs in your race motor, you're probably asking for trouble, regardless of 6 grand or 8.
-R
05-13-2008, 02:31 PM
#66
Rennlist Member
Waayyyy back on post #47, some dude mentioned the use of lightweight vavle train components contributing to a higher redline, not as a direct power adder. The inference is that you would get more HP due to the higher redline, not due to the use of lightweight components taken to the stock redline. 
05-26-2008, 03:06 PM
#67
Addict
Rennlist Member
Rennlist Member
Thread Starter
Update:
Since the motor has gone in, I've been gently breaking it in. Never past 4000 rpm & never much past half throttle. So now that it has had its first oil change and a GT oil cooler has been added, it's time to go WOT to redline.
Over the past 10 months as we've worked on this motor at Jim's place, I've had to drive through this tunnel each time to get there. And each time (must be close to 100 times total), I'd dream of how this motor would sound. I finally got to hear it in reality. Come for a ride:
There's a higher quality version on the youtube website if you double click this video.
Since the motor has gone in, I've been gently breaking it in. Never past 4000 rpm & never much past half throttle. So now that it has had its first oil change and a GT oil cooler has been added, it's time to go WOT to redline.
Over the past 10 months as we've worked on this motor at Jim's place, I've had to drive through this tunnel each time to get there. And each time (must be close to 100 times total), I'd dream of how this motor would sound. I finally got to hear it in reality. Come for a ride:
There's a higher quality version on the youtube website if you double click this video.
05-26-2008, 08:22 PM
#70
Drifting
I can't wait to see the dyno results, as I might be doing a very similar build in the next 2 years or so once my stock motor kicks the bucket. This will be *great* info for me! Awesome.
05-27-2008, 01:25 AM
#72
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
05-27-2008, 01:45 AM
#73
Three Wheelin'
Join Date: Feb 2002
Posts: 1,663
Likes: 0
Received 0 Likes
on
0 Posts
As an FYI to anyone looking to play aroung with cams like these... make sure you compensate for the additional duration of the cams and do what is needed to keep the cylinder pressure (effective compression ratio) up to where things were before installing the longer duration cams.
If you do not do anything, you'll likely get a big "bwahh" sound out of the exhaust pipe with no increase in power, possibly less power than stock...
For those interested with GTS's, I have calc'd these same cams within the GTS engine. Given the relatively high compression of the GTS, without other mods, the specs for these cams look good to go for the S3 cores. GT cores also look good, but possibly on the ragged egde for 91 octane folks.
Right now, I am getting cams ground on both GT and S3 cores, so we'll see how it goes when I install these cams in my own GTS engine. It will likely be later this summer before this will get done, but I will surely post the results.
In the mean time, enjoy the sound... From first hand listening, it's deinfately intoxicating
If you do not do anything, you'll likely get a big "bwahh" sound out of the exhaust pipe with no increase in power, possibly less power than stock...
For those interested with GTS's, I have calc'd these same cams within the GTS engine. Given the relatively high compression of the GTS, without other mods, the specs for these cams look good to go for the S3 cores. GT cores also look good, but possibly on the ragged egde for 91 octane folks.
Right now, I am getting cams ground on both GT and S3 cores, so we'll see how it goes when I install these cams in my own GTS engine. It will likely be later this summer before this will get done, but I will surely post the results.
In the mean time, enjoy the sound... From first hand listening, it's deinfately intoxicating
