Individual cam timing idea
09-24-2007, 02:27 PM
#1
Rennlist Member
Thread Starter
Individual cam timing idea
I was pondering this yesterday, and wanted to see what everyone thought. One of the areas where the 4v 928 lacks tunability is in the cam lobe centerline adjustment between the intake and exhaust cams, since the exhaust cam gets the timing belt cog and the intake cam just follows along with a cam chain. It always seemed a little strange to me to be mechanically manipulating the exhaust cam to get a particular reading from the intake cam while doing cam timing.
Sterling is running the 968 cam chain tensioners which uses a longer cam chain with a solenoid which controls the tensioner pressure. More tension, more advance I believe.
Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
PIA? yes.
Worth it? maybe not.
Is it really worth the effort? When your talking about this level of tuning, probably not for a typical driver.
But for the rest of us lunatics, and you out there know who you are, does it seem doable? This really seems to be the last component of finite tuning on our cars. Basically "Otting" your 928.
definition
Ott - noun. As in Professor. Distinguished resident of Mosier Oregon who has either by idea, act or inspiration, single handedly improved performance of the 928 more in the last 5 years, than Porsche did in the 18 years the car was being produced.
Ott-ing - verb. The act of extracting every last possible iota of performance out of a 928.
Sterling is running the 968 cam chain tensioners which uses a longer cam chain with a solenoid which controls the tensioner pressure. More tension, more advance I believe.
Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
PIA? yes.
Worth it? maybe not.
Is it really worth the effort? When your talking about this level of tuning, probably not for a typical driver.
But for the rest of us lunatics, and you out there know who you are, does it seem doable? This really seems to be the last component of finite tuning on our cars. Basically "Otting" your 928.
definition
Ott - noun. As in Professor. Distinguished resident of Mosier Oregon who has either by idea, act or inspiration, single handedly improved performance of the 928 more in the last 5 years, than Porsche did in the 18 years the car was being produced.
Ott-ing - verb. The act of extracting every last possible iota of performance out of a 928.
09-24-2007, 04:33 PM
#2
Rennlist Member
Otters: those who follow the principals and practices of the great Ott.
Otter-ites: see above
Ott-o-philes: those who study the ways of the Ott, but may or may not apply the principals and practices of the Ott.
Ott-avangelists: those who preach the religion of the Ott and seek to convert others to the Otter belief system.
Ottness: the degree to which one has adopted the principals and practices of the great Ott. Usually measured in US dollars expended and dyno run numbers.
Otta-ristas: those who have banded up to further the agenda of the great Ott at any cost, including leading an armed insurgency in the 928 World.
Anti-Otterites: those who question and deny the wisdom of the great Ott.
Otta-be's: those who seek to follow the principals and practices of the great Ott, but for one reason or another, have not been able to. They are known to post inane posts in otherwise useful 928 technical threads.
Ottarazzi: those who document the principals and practices of the great Ott, usually in the form of dyno run numbers, photos, and by quoting the great Ott.
------------
Sorry Adam, I couldn't resist.
Otter-ites: see above
Ott-o-philes: those who study the ways of the Ott, but may or may not apply the principals and practices of the Ott.
Ott-avangelists: those who preach the religion of the Ott and seek to convert others to the Otter belief system.
Ottness: the degree to which one has adopted the principals and practices of the great Ott. Usually measured in US dollars expended and dyno run numbers.
Otta-ristas: those who have banded up to further the agenda of the great Ott at any cost, including leading an armed insurgency in the 928 World.
Anti-Otterites: those who question and deny the wisdom of the great Ott.
Otta-be's: those who seek to follow the principals and practices of the great Ott, but for one reason or another, have not been able to. They are known to post inane posts in otherwise useful 928 technical threads.
Ottarazzi: those who document the principals and practices of the great Ott, usually in the form of dyno run numbers, photos, and by quoting the great Ott.
------------
Sorry Adam, I couldn't resist.
09-24-2007, 04:50 PM
#3
Rennlist Member
Thread Starter
OT: but going with the flow
Ott-o-licious - adjective. A descriptor commonly used to described the rear perspective of a 928 shod with Ott rear fender flares.
09-24-2007, 04:50 PM
#4
ATB - post 70 here: https://rennlist.com/forums/944-turbo-and-turbo-s-forum/242924-3-liter-16-valve-turbo-thread.html
Two smaller honda Cogs, and some changes to the belt size and some math to make sure they are spinning at the right speed.
Two smaller honda Cogs, and some changes to the belt size and some math to make sure they are spinning at the right speed.
09-24-2007, 04:55 PM
#5
Rennlist Member
Thread Starter
Hey Brendan, cool concept but looks like a lot of work (machining on the cams), and a lot of math. Is there a belt made that would run both banks? It would truly suck to have one bank go out do to a failed belt, and the other, still tied to the crank, hammer away. 
Still, it is a cool concept. Was the motor in the pic eventually ran? In the pics it looks like its still in the design stage.
Still, it is a cool concept. Was the motor in the pic eventually ran? In the pics it looks like its still in the design stage.
09-24-2007, 04:58 PM
#6
Rennlist Member
We used to mess with cam timing on racing motorcycle engines by 'slotting' the gears.
As the 928 cams dont have a removable sprockets there's a whole lot of maching then involved.
As the 928 cams dont have a removable sprockets there's a whole lot of maching then involved.
09-24-2007, 05:06 PM
#7
Three Wheelin'
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Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
Good idea. Needs to be Porkenized.
I see:
A) must fit under valve covers
B) should have some sort of pointer-and-dial with stock settings at zero
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09-24-2007, 05:08 PM
#8
Hey Brendan, cool concept but looks like a lot of work (machining on the cams), and a lot of math. Is there a belt made that would run both banks? It would truly suck to have one bank go out do to a failed belt, and the other, still tied to the crank, hammer away.
Still, it is a cool concept. Was the motor in the pic eventually ran? In the pics it looks like its still in the design stage.
Still, it is a cool concept. Was the motor in the pic eventually ran? In the pics it looks like its still in the design stage.
The other option is more towards what you mentioned, in having something on the cam teeth where the chain is.
But Sterling did that, and it would slip and I think eventually broke, but I know it slipped. The teeth were bolted to the cam, and was never tight enough.
Knowing what honda and everyone else does NOW, they simply have a fluid coupling and the cam is usually multiple parts, making it turn on its own axis for more or less lift. BMW doesn't even have a throttle plate on thier newer cars - all throttle control is through the lift and duration of the cams. Amazing.
If you are going so far as to want to adjust both, its a smaller step to automatic adjustment. I have wondered repeatedly about what it would really entail to make a fully variable cam accutation for our engine.
09-24-2007, 05:29 PM
#9
Supercharged
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Don't forget:
Otta-tack - This is a medical condition no one should have. But if you do, good therapy is to get back working on your p-car days after you get home from the hospital.
Otta-tack - This is a medical condition no one should have. But if you do, good therapy is to get back working on your p-car days after you get home from the hospital.
09-24-2007, 05:40 PM
#10
Rennlist Member
actually, even though the movement is on the exhaust cam, the adjustment is for the intake cam to make that right and then the exhaust cam is along for the ride. Ive got mine set at 2mm for 20 degrees advanced of TDC, and both cams are set when engine was cold. the hp and exhaust sound was noticable for the .3mm change. (equates to about 1.5 cam degree change)
Hard to imagine that this would be an issue, but when going back to the dyno, the hp went from 310 back up to 318. kind of hard to imagine that this kind of change would result in that kind of performance difference. the audible note was the most stunning. this is very apparent on the in car video for before and after adjustment.
mk
Hard to imagine that this would be an issue, but when going back to the dyno, the hp went from 310 back up to 318. kind of hard to imagine that this kind of change would result in that kind of performance difference. the audible note was the most stunning. this is very apparent on the in car video for before and after adjustment.
mk
I was pondering this yesterday, and wanted to see what everyone thought. One of the areas where the 4v 928 lacks tunability is in the cam lobe centerline adjustment between the intake and exhaust cams, since the exhaust cam gets the timing belt cog and the intake cam just follows along with a cam chain. It always seemed a little strange to me to be mechanically manipulating the exhaust cam to get a particular reading from the intake cam while doing cam timing.
Sterling is running the 968 cam chain tensioners which uses a longer cam chain with a solenoid which controls the tensioner pressure. More tension, more advance I believe.
Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
PIA? yes.
Worth it? maybe not.
Is it really worth the effort? When your talking about this level of tuning, probably not for a typical driver.
But for the rest of us lunatics, and you out there know who you are, does it seem doable? This really seems to be the last component of finite tuning on our cars. Basically "Otting" your 928.
definition
Ott - noun. As in Professor. Distinguished resident of Mosier Oregon who has either by idea, act or inspiration, single handedly improved performance of the 928 more in the last 5 years, than Porsche did in the 18 years the car was being produced.
Ott-ing - verb. The act of extracting every last possible iota of performance out of a 928.
Sterling is running the 968 cam chain tensioners which uses a longer cam chain with a solenoid which controls the tensioner pressure. More tension, more advance I believe.
Couldn't a similar system, but with a manual adjuster, be used to lock the adjuster in place for an optimized cam setting. I'm not talking about having the advance feature while the car is running, but doing static cam timing, locking the manuallly adjusted cam chain tensioner in place, and then closing it up and running the car as set.
PIA? yes.
Worth it? maybe not.
Is it really worth the effort? When your talking about this level of tuning, probably not for a typical driver.
But for the rest of us lunatics, and you out there know who you are, does it seem doable? This really seems to be the last component of finite tuning on our cars. Basically "Otting" your 928.
definition
Ott - noun. As in Professor. Distinguished resident of Mosier Oregon who has either by idea, act or inspiration, single handedly improved performance of the 928 more in the last 5 years, than Porsche did in the 18 years the car was being produced.
Ott-ing - verb. The act of extracting every last possible iota of performance out of a 928.
09-24-2007, 05:50 PM
#11
Three Wheelin'
If anyone attempts this on a 928 they should be locked in a padded room. If they manage to escape they'd have a world of possibilities, stronger modern belts, valve timing adjustabilty on-the-dyno, keeping the waterpump on a seperate belt etc.
09-24-2007, 06:38 PM
#12
The Porsche cogs use an odd inch pitch so you would have to replace the oil pump's too. It would be nice to have the adjustability of 2 cogs.
If anyone attempts this on a 928 they should be locked in a padded room. If they manage to escape they'd have a world of possibilities, stronger modern belts, valve timing adjustabilty on-the-dyno, keeping the waterpump on a seperate belt etc.
If anyone attempts this on a 928 they should be locked in a padded room. If they manage to escape they'd have a world of possibilities, stronger modern belts, valve timing adjustabilty on-the-dyno, keeping the waterpump on a seperate belt etc.
Honda Deals with the entire variable valve timing situation with some pneumatic machinery that takes up a circular area about 4 inches by 2 inches. So with that, they get 240hp and 160lbft out of 2L at 8800rpm, with piston speeds into f1 territory.
The Dodge viper, essentially the equivalent to a single-celled amoeba compared to Today's BMWs and Porsches, now has variable valve timing on its ONE cam.
BMW:
09-24-2007, 06:49 PM
#13
Three Wheelin'
Does any OEM use an electric water pump? It would be nice on a high performance or race car but I'm weary of aftermarket stuff with poor reliability. I wouldn't use a fuel or water pump from any hot rod type supplier.
09-24-2007, 07:55 PM
#14
My Honda has an electric power steering pump.
Last edited by BC; 09-24-2007 at 08:20 PM.
09-24-2007, 07:57 PM
#15
Yes, BMW 3-series OEM has an electric water pump, they also utilize it as a thermostat as well.
I bought an elec water pump from a company called CSR. I got the mdl, 925. I've been testing
it on another non-porsche project I've got . Its been working very well, I was going to test it
on the car its on with the thinking that if all worked out well I'd put it on my 928 stroker mtr
when its done .
I bought an elec water pump from a company called CSR. I got the mdl, 925. I've been testing
it on another non-porsche project I've got . Its been working very well, I was going to test it
on the car its on with the thinking that if all worked out well I'd put it on my 928 stroker mtr
when its done .