Built Head Questions
Apr 18, 2008, 01:11 PM
#46
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I will stick with the stocker with the copper spray (seems to work well for me)
Now I am searching the web more for the individual parts for my build and have a question. (go figure, huh? )
what is the main difference in Manganeese-bronze verses copper guides on the exhaust valves? (noticed they dont off the copper for the intake)
Now I am searching the web more for the individual parts for my build and have a question. (go figure, huh? )
what is the main difference in Manganeese-bronze verses copper guides on the exhaust valves? (noticed they dont off the copper for the intake)
Apr 18, 2008, 07:57 PM
#48
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No I wasn't. I'm not saying that the entire 23% - 10% gain was attributable to the valves, but David Buschur seemed fit to mention that the head really took off with the valves in it. Either he wants to sell valves, or that's what he felt was the main contributor to the numbers increase. Do you know how much "additional" porting he did? Maybe he just cartrige rolled it but felt it would be wrong to post the new numbers without mentioning he'd done additional work. We're mincing words here. There's no real resolve to this argument without david buschur explaining exactly how the test went that fateful day 5 years ago.
. I understand now where you are coming from, and, in fact agree with you... now that the effects of the demon grog have finally ebbed.I am just too old and come from a time when most automotive production heads only had two valves per pot. In my retrograde mind I was dimly recalling a scenario, way back then(30+ years ago), wherein a SoCal head porting guru was telling me that it was not worth it to change from the stock 46mm intake valve in my 1975 BMW 2002 factory turbo sedan, to the 1mm larger Alpina intake valve.
Later after rereading your posts I remembered that the Evo head has 4 valves per cylinder(duh!). And that all four valves woud be increased in diameter. Thus, a 1mm, or 2mm increase in the diameters of all four valves per cylinder could have a significant impact on flow.
Age has its rewards
Last edited by sparky; Apr 18, 2008 at 08:27 PM.
Apr 19, 2008, 05:36 PM
#51
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I was just yanking your chain under the influence of a few late night pints . I understand now where you are coming from, and, in fact agree with you... now that the effects of the demon grog have finally ebbed.
I am just too old and come from a time when most automotive production heads only had two valves per pot. In my retrograde mind I was dimly recalling a scenario, way back then(30+ years ago), wherein a SoCal head porting guru was telling me that it was not worth it to change from the stock 46mm intake valve in my 1975 BMW 2002 factory turbo sedan, to the 1mm larger Alpina intake valve.
Later after rereading your posts I remembered that the Evo head has 4 valves per cylinder(duh!). And that all four valves woud be increased in diameter. Thus, a 1mm, or 2mm increase in the diameters of all four valves per cylinder could have a significant impact on flow.
Age has its rewards
. I understand now where you are coming from, and, in fact agree with you... now that the effects of the demon grog have finally ebbed.I am just too old and come from a time when most automotive production heads only had two valves per pot. In my retrograde mind I was dimly recalling a scenario, way back then(30+ years ago), wherein a SoCal head porting guru was telling me that it was not worth it to change from the stock 46mm intake valve in my 1975 BMW 2002 factory turbo sedan, to the 1mm larger Alpina intake valve.
Later after rereading your posts I remembered that the Evo head has 4 valves per cylinder(duh!). And that all four valves woud be increased in diameter. Thus, a 1mm, or 2mm increase in the diameters of all four valves per cylinder could have a significant impact on flow.
Age has its rewards
Apr 22, 2008, 01:25 PM
#52
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I have decided to go with the +1mm Iconal exhaust valves, +2mm Nitrided intake valves, new valve guides, new spring locators/seats (shim that the spring sits on)
Do the valve seats need to be replaced? Or can they just be recut for the new sized valves?
Do the valve seats need to be replaced? Or can they just be recut for the new sized valves?
Apr 30, 2008, 10:12 PM
#53
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[QUOTE=icantdrive75;5560329]I'd stay away from installing new seats. I've heard they're a proverbial ***** on an EVO head, even to the point that if the seats are gone the head is gone. I got valve guides from FFWD connection. Pretty sure they're supertechs. Pick your favorite shop and I'm sure they can order you some.
QUOTE]
just a fyi..if your installing them yourself, measure the hole and the guide before you begin, the Supertech guide runs a little big
seats need to be replaced to do 2mm..besides there will be a point of diminshing return on such an endevor. The port is your restriction, not the valve. I am not sure of your combo, but you can make over 1000whp with a 1mm oversize valve.
QUOTE]
just a fyi..if your installing them yourself, measure the hole and the guide before you begin, the Supertech guide runs a little big
seats need to be replaced to do 2mm..besides there will be a point of diminshing return on such an endevor. The port is your restriction, not the valve. I am not sure of your combo, but you can make over 1000whp with a 1mm oversize valve.
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