SLORYDER Posted June 1, 2010 Report Share Posted June 1, 2010 Some coolheads such as ours force most of the coolant to flow around the exhaust passages which according to builders I have talked to will show an increase in hp. My understanding is that when the exhaust gas is too hot you are robbed of hp and cooling the cylinder around the exhaust outlet is one key to lowering the temp here. Pro design head does not force any coolant around the exhaust passage. I believe the stock head does much more so then Pro design. Jerry I was always under the impression that a hot passageway was benificial to to gas flow, which is why people wrap their headers with fiber-wrap....? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 1, 2010 Report Share Posted June 1, 2010 I was always under the impression that a hot passageway was benificial to to gas flow, which is why people wrap their headers with fiber-wrap....? Keeping heat in the pipe vs. keeping heat in the cylinder are TOTALLY different... Quote Link to comment Share on other sites More sharing options...
Chariot Performance Posted June 1, 2010 Report Share Posted June 1, 2010 I was always under the impression that a hot passageway was benificial to to gas flow, which is why people wrap their headers with fiber-wrap....? What I have been told is at the cylinder exhaust port coolant flow to cool the cylinder is beneficial. As you point out the exhaust pipe is a different story. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 1, 2010 Report Share Posted June 1, 2010 Keeping heat in the pipe vs. keeping heat in the cylinder are TOTALLY different... Not when youre talking about performance. The exhaust port and the header both provide the same service by providing a passageway for the exhaust gasses to exit. The exhaust port length is used when calculating the tuned length of a pipe. I don't see how a cooler exhaust port could add horsepower. Quote Link to comment Share on other sites More sharing options...
ramon Posted June 1, 2010 Report Share Posted June 1, 2010 It's always cool to get head hahahahah!! Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 2, 2010 Report Share Posted June 2, 2010 Not when youre talking about performance. The exhaust port and the header both provide the same service by providing a passageway for the exhaust gasses to exit. The exhaust port length is used when calculating the tuned length of a pipe. I don't see how a cooler exhaust port could add horsepower. There's just a little bit more to it than that.... It think what he is trying to say is the exhaust port is the hottest part on the engine...and a cool engine makes more power. Thus...cooling the exhaust port will make more power. As far as the exhaust, on a two stroke...that's a different story. Some of the burnt/unburnt fuel actually re-enters the combustion chamber and is processed again. Along those lines is where heat in the exhaust makes more power....but of course there is a ceiling. That's why some people tune with EGTs. But they have to have a baseline first. There is no such thing as this temp is the proper temp to run a motor...much more to it than that. Quote Link to comment Share on other sites More sharing options...
TexasBansheeMan Posted June 2, 2010 Report Share Posted June 2, 2010 I love my Coolhead, and I now have a Vitos for my BB. Changing the domes is very nice. Once you mill a stock head, its milled for life, with domes you can go back if you dont like the change, or change setups. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Report Share Posted June 2, 2010 It think what he is trying to say is the exhaust port is the hottest part on the engine...and a cool engine makes more power. Thus...cooling the exhaust port will make more power. I don't think there is any proof that a cool head lowers the coolant temperature, which would signify a decrease in the intake charge temperature, which imo is the only way to make more power by lowering the temperature inside the cylinder. As far as the exhaust, on a two stroke...that's a different story. Some of the burnt/unburnt fuel actually re-enters the combustion chamber and is processed again. Along those lines is where heat in the exhaust makes more power....but of course there is a ceiling. That's why some people tune with EGTs. But they have to have a baseline first. There is no such thing as this temp is the proper temp to run a motor...much more to it than that. Yeag but I still think it is a stretch to say that by forcing a little more coolant to the exhaust port side will give a significant increase in HP. Definately sounds better for the life of the engine, but to say it adds power is a stretch. I love my Coolhead, and I now have a Vitos for my BB. Changing the domes is very nice. Once you mill a stock head, its milled for life, with domes you can go back if you dont like the change, or change setups. You can do 2 setups with stock heads and still be in it about half the price of two cool head setups. Not trying to start any arguments guys, just please try to say things that make sense. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 2, 2010 Report Share Posted June 2, 2010 I agree. The combustion needs to happen at a certain temperature to be efficient. Any more or less is losing power and/or reliability... Quote Link to comment Share on other sites More sharing options...
Silentsoul Posted June 2, 2010 Report Share Posted June 2, 2010 Pros: Increased power Interchangeability Looks cool if you're into that kind of thing Better sealing over a stock head in extreme high hp applications (doesn't seem to be a problem w/ most engines) Cons: Power increase is minute over a stock shaved head Costs 3-5x more than a stock shaved head Ruins the sleeper look (a con to me at least) I was wondering how you can shave off of a stock head? Can you shave enough that u have to run race gas? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted June 2, 2010 Report Share Posted June 2, 2010 Absolutely. Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Report Share Posted June 2, 2010 (edited) I was wondering how you can shave off of a stock head? Can you shave enough that u have to run race gas? Uhm, I'm not sure Let's see Stock squish is around .068" using stock gaskets, .080" with a moose head gasket. You shave off .025" to safely run premium, typically, which puts your squish at around .043" Another .010" would put yout squish at around .033", which is about the limit. You could probably get abay with 50/50 race gas/ premium unleaded at this stage. If you plan on running race gas or alky, you should get the head re-chambered. Mull engineering does it for a good price. Pump gas or 50/50, a stock shaved head should work.It is always recommended to check your squish first and your compression after. .025" is definately be safe for pump gas though, unless you run no head gasket. Edited June 2, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
shawn941 Posted June 2, 2010 Report Share Posted June 2, 2010 I was wondering how you can shave off of a stock head? Can you shave enough that u have to run race gas? i just installed mine,,,im borderline,,,160 psi each side,,,im runnin 2 gallons of 110 and 3 gallons of 93,,,thing fukin rips man Quote Link to comment Share on other sites More sharing options...
shawn941 Posted June 2, 2010 Report Share Posted June 2, 2010 I was wondering how you can shave off of a stock head? Can you shave enough that u have to run race gas? i just installed mine,,,im borderline,,,160 psi each side,,,im runnin 2 gallons of 110 and 3 gallons of 93,,,thing fukin rips man Quote Link to comment Share on other sites More sharing options...
SLORYDER Posted June 2, 2010 Report Share Posted June 2, 2010 (edited) i just installed mine,,,im borderline,,,160 psi each side,,,im runnin 2 gallons of 110 and 3 gallons of 93,,,thing fukin rips man How much did you shave? Elevation? Edited June 2, 2010 by SLORYDER Quote Link to comment Share on other sites More sharing options...
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