Blown Head Gasket
05-01-2010, 06:05 PM
#41
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I was just saying that iron or alloy...there would still have been serious damage. Although of course the iron is the stronger platform.
I also doubt its the limit of pump gas. Perhaps with the high CR it is, but more power will be safely achievable on pump, with a lower CR.
There are little 2.0 4pots making 800bhp on pump gas, so a 6.0+ V8 with a bit of boost shouldnt struggle to do similar.
I also doubt its the limit of pump gas. Perhaps with the high CR it is, but more power will be safely achievable on pump, with a lower CR.
There are little 2.0 4pots making 800bhp on pump gas, so a 6.0+ V8 with a bit of boost shouldnt struggle to do similar.
05-01-2010, 08:55 PM
#42
Subaru's 99.5mm bore of the 2.5 can easily handle 30psi on pump fuel with mid 8's CR
Which is basically a 4.0" bore, albeit with very short stroke.
My LS is safely running 20psi on 9.5:1 CR on equivalent to 93 octane, albeit with a centri.
A CR of 8.7:1 would easily handle 20psi no problem at all IMO.
Which is basically a 4.0" bore, albeit with very short stroke.
My LS is safely running 20psi on 9.5:1 CR on equivalent to 93 octane, albeit with a centri.
A CR of 8.7:1 would easily handle 20psi no problem at all IMO.
20psi is not possible on my motor, 91 oct, desert heat and no humidity, I'm under the worst possible circumstances. I've tried 16psi on 91 previously and had to pull so much timing out to keep detonation away that it made less power than 13 psi.
Surbaru's have really bad flow and don't make much power, I could probably run 30-40psi on 91 my car too if I restricted flow. Making power on a given fuel is all about finding the sweet spot of boost vs timing vs detonation.
Running lots of boost on crappy gas is for fools who like to spend money fixing engines. It's much better to play it safe... or just run a good fuel like E85 which is very resistant to detonation.
05-02-2010, 09:06 AM
#43
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Surbaru's have really bad flow and don't make much power, I could probably run 30-40psi on 91 my car too if I restricted flow. Making power on a given fuel is all about finding the sweet spot of boost vs timing vs detonation.
Running lots of boost on crappy gas is for fools who like to spend money fixing engines. It's much better to play it safe... or just run a good fuel like E85 which is very resistant to detonation.
I'd say they are pretty damn good engines actually. I know of plenty of others runnin 9's and low 10's
When you show me LS engines that can easily and reliably make 250-300bhp/litre on pump fuel, then you can say the Subaru have bad flow. ( although I'm sure its possible )
Some are making quite a bit more than that on race fuel.
Last edited by stevieturbo; 05-02-2010 at 09:18 AM.
05-02-2010, 10:05 AM
#44
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How exactly have you come to the conclusion that Subaru engine's have bad flow ? A friend in the UK has run 8.9s at 165mph in his. The fastest manual Impreza in the world.
I'd say they are pretty damn good engines actually. I know of plenty of others runnin 9's and low 10's
When you show me LS engines that can easily and reliably make 250-300bhp/litre on pump fuel, then you can say the Subaru have bad flow. ( although I'm sure its possible )
Some are making quite a bit more than that on race fuel.
I'd say they are pretty damn good engines actually. I know of plenty of others runnin 9's and low 10's
When you show me LS engines that can easily and reliably make 250-300bhp/litre on pump fuel, then you can say the Subaru have bad flow. ( although I'm sure its possible )
Some are making quite a bit more than that on race fuel.
05-02-2010, 10:11 AM
#45
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The semi open decks can easily handle 500bhp without modification. Although if seeking lots of power, just use a closed deck block or fit uprated liners to the semi.
Even the crappy old open deck will make a very easy 200bhp/litre and be totally reliable.
Ive built dozens of them and never had any problems. Ans some people abuse the life out of them !
But the topic isnt about that
Even the crappy old open deck will make a very easy 200bhp/litre and be totally reliable.
Ive built dozens of them and never had any problems. Ans some people abuse the life out of them !
But the topic isnt about that
