16v vs 8v head turbo application - max static compression ?
01-15-2011, 12:02 PM
#16
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this is my priority list when engine building.
Head gasket stuff
oiling bottom end .
reduce weight were possible
tidy up ports .
address cam timing with cam wheels so its adjustable to separate lobe centers.
turbo selection .
good ancillaries. breather perhaps vac pump high mount injectors wiz bang ignition. good inter cooler.good pipes .water spay ..
the cams bolt on the top you can always come back to them..
So Far i have seen no evidence that $1000 can be justified on changing cams on a 4valve per cylinder turbo engine..
If any wants to school me on this please do
Head gasket stuff
oiling bottom end .
reduce weight were possible
tidy up ports .
address cam timing with cam wheels so its adjustable to separate lobe centers.
turbo selection .
good ancillaries. breather perhaps vac pump high mount injectors wiz bang ignition. good inter cooler.good pipes .water spay ..
the cams bolt on the top you can always come back to them..
So Far i have seen no evidence that $1000 can be justified on changing cams on a 4valve per cylinder turbo engine..
If any wants to school me on this please do
01-15-2011, 12:11 PM
#17
01-15-2011, 06:29 PM
#18
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>i went to fill up and fainted when i saw $1.53 L
In the UK, they don't have E85, so I'm stuck with Shell Optimax 99 RON or equivalent and as for petrol prices here, well, the local Shell is around UK 1.30L so don't feel too hard done by !
I'm not in any rush on the project, and I'll wait for the main components to come up at decent prices, given that I'll most likely be combining the 2.7 block with an S2 head and crank it may take quite a while to source the two doner engines - might be easiest getting non runners and stripping them out !
In the UK, they don't have E85, so I'm stuck with Shell Optimax 99 RON or equivalent and as for petrol prices here, well, the local Shell is around UK 1.30L so don't feel too hard done by !
I'm not in any rush on the project, and I'll wait for the main components to come up at decent prices, given that I'll most likely be combining the 2.7 block with an S2 head and crank it may take quite a while to source the two doner engines - might be easiest getting non runners and stripping them out !
01-15-2011, 06:46 PM
#19
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Korenwolf if your in the UK I would speak to barry at hartech.org he's building a 16V sleeved 3.0 litre variocam atm. This is his next project after his 3.0 8v which I belive was very sucessfull. Doesn't sound much after some of the builds on rennlist but there's not a huge amount going on on the UK 944 scene, not a big enough market!
if you want to go alone then try porsche-apart for an S2 crank and maybe a head. They had cranks available when I was considering a 2.8 stroker engine for my 2.5 turbo rebuild.
if you want to go alone then try porsche-apart for an S2 crank and maybe a head. They had cranks available when I was considering a 2.8 stroker engine for my 2.5 turbo rebuild.
01-15-2011, 10:00 PM
#21
Rainman
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also...awic?
01-15-2011, 10:18 PM
#22
Formula One Spin Doctor
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01-16-2011, 12:34 AM
#23
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"keep the boost low " elaborate please wayne as you see all kinds of builds give me an example of some one goin to high compression with a high octane build . the only real world examples i have is my beema wich was 10.5:1 13psi 38 degrees of timing on LPG and it was a dirty ol M10 8valve
so if we times pressure ratio by comp ratio we get 18:1 wich is what
and guys running with 98 ..
LPG turbo six fords down here run 40psi on 8.0:1 again a ****ty old 2v/cylinder engine
so is that like 3.5 pressure ratio by 8.0 thats up over 25:1
yeh i know those PRxCR calcs are only a very rough guide but what else is out there ..??
so if we times pressure ratio by comp ratio we get 18:1 wich is what
and guys running with 98 ..
LPG turbo six fords down here run 40psi on 8.0:1 again a ****ty old 2v/cylinder engine
so is that like 3.5 pressure ratio by 8.0 thats up over 25:1
yeh i know those PRxCR calcs are only a very rough guide but what else is out there ..??
01-16-2011, 01:40 AM
#24
Formula One Spin Doctor
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Sorry , I have no LPG experience and 13 psi would be considered low boost IMO. State your BHP, makes it easier to understand what kind of cylinder pressures being experienced.
38deg does sound excessive for timing, does it make power all the way ...
With 105 octane and lower i would suggest no higher than 8.5 on the 8V, 9.5 on the 16V, if you want to run 1.4 bar and above.
The Higher CR makes the engine 2 sensitive to pre-ignition on such a low octane and you can make more power and TQ by upping the boost before pre-ignition with the lower CR, of course you will need more boost but it will ultimately be less prone to breakage and make more power.
If you are planning and running no more than 1 bar then you can go one point higher with no issues.
In the past I have done setups focused on pump gas and have used CR's as low as 7.5:1 on a 2.6 /6 cylinder and it did 740 WHP on 93 octane with no issues and showed very little temperature sensitivity to knock.
.
38deg does sound excessive for timing, does it make power all the way ...
With 105 octane and lower i would suggest no higher than 8.5 on the 8V, 9.5 on the 16V, if you want to run 1.4 bar and above.
The Higher CR makes the engine 2 sensitive to pre-ignition on such a low octane and you can make more power and TQ by upping the boost before pre-ignition with the lower CR, of course you will need more boost but it will ultimately be less prone to breakage and make more power.
If you are planning and running no more than 1 bar then you can go one point higher with no issues.
In the past I have done setups focused on pump gas and have used CR's as low as 7.5:1 on a 2.6 /6 cylinder and it did 740 WHP on 93 octane with no issues and showed very little temperature sensitivity to knock.
.
Last edited by A.Wayne; 01-16-2011 at 02:00 AM.
01-16-2011, 03:03 AM
#25
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With 105 octane and lower i would suggest no higher 9.5 on the 16V, if you want to run 1.4 bar and above.
The Higher CR makes the engine 2 sensitive to pre-ignition on such a low octane and you can make more power and TQ by upping the boost before pre-ignition with the lower CR, of course you will need more boost but it will ultimately be less prone to breakage and make more power.
If you are planning and running no more than 1 bar then you can go one point higher with no issues.
In the past I have done setups focused on pump gas and have used CR's as low as 7.5:1 on a 2.6 /6 cylinder and it did 740 WHP on 93 octane with no issues and showed very little temperature sensitivity to knock.
.
The Higher CR makes the engine 2 sensitive to pre-ignition on such a low octane and you can make more power and TQ by upping the boost before pre-ignition with the lower CR, of course you will need more boost but it will ultimately be less prone to breakage and make more power.
If you are planning and running no more than 1 bar then you can go one point higher with no issues.
In the past I have done setups focused on pump gas and have used CR's as low as 7.5:1 on a 2.6 /6 cylinder and it did 740 WHP on 93 octane with no issues and showed very little temperature sensitivity to knock.
.
01-16-2011, 03:17 AM
#26
Rennlist Member
http://forums.bimmerforums.com/forum....php?t=1575817
...sure it's a little laggy...but there's some $$$ being burnt out there....
...sure it's a little laggy...but there's some $$$ being burnt out there....
01-16-2011, 03:35 AM
#28
Rennlist Member
9000cc injectors!! That's a little bit of fuel being used...
01-16-2011, 05:28 AM
#30
Three Wheelin'
