switching the RA head to evo dohc head
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Joined: Aug 2004
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From: A
Originally Posted by drivethrufinch3
the thing about dohc and sohc is i always though dohc was better but at technology goes on it doesnt seem that. the new mustang gt is soch, most of the mercadies sports cars are sohc, the mercadies 16 is sohc and thats a super car, so if sohc is better gas milage or something, u dont need that on a super car, so i just dont understand, i guess sohc is better when you do something(what ever their doing) maybe someone can shed some light on this for me
You would run into some problems. You would not have the Mivec anymore for one. For 2 you woul dhave to make sure all the valve clearances were the same becouse if the valves stem heights are different you will be boxing your pistons. Not like a LS Vtec were it is just wiring.
Chris
Chris
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From: Lakewood, CA
The advantages of a DOHC setup is a reduced length of the rocker arm assemblies (or a complete elimination of them by going to a cam-on-bucket design) that reduces the weight of the valve train thereby allowing you to safely rev the engine higher. You can also tune each individual valve independently for maximum tunability.
The disadvantages of a DOHC are that the head is larger and heavier than a SOHC design, it has more moving parts in it and thus is slightly more suseceptible to failure, and are more difficult to work on.
On a 4G69 motor with its 100mm stroke length, it is NOT going to be a high-revving engine, so most of the benifits of a twincam setup are negated. IMO You'd be better served by just porting the MIVEC head that's already there.
The disadvantages of a DOHC are that the head is larger and heavier than a SOHC design, it has more moving parts in it and thus is slightly more suseceptible to failure, and are more difficult to work on.
On a 4G69 motor with its 100mm stroke length, it is NOT going to be a high-revving engine, so most of the benifits of a twincam setup are negated. IMO You'd be better served by just porting the MIVEC head that's already there.
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From: ATL
Originally Posted by turbonutter
On a 4G69 motor with its 100mm stroke length, it is NOT going to be a high-revving engine, so most of the benifits of a twincam setup are negated. IMO You'd be better served by just porting the MIVEC head that's already there.
But, yeah. Everything he said too. The new Honda Accord V6 is SOHC and puts 240 hp out of a 3.0L engine on regular gas.
On DOHC engines with "I-Vtec", the cam profile can be advanced retarded. At higher revs the intake and extake (exhaust
) valve timings can be overlaped to have a sort of syphon effect on the exhaust leaving and the intake charge comming in. You can not manipulate this on a SOHC engine because both lobes are on one shaft.
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From: Birmingham, AL
AFAIK, Nissan and Toyota are the only ones putting DOHC and variable valve timing on a V6's (and V8's). But I think they only affect the intake side of things. I am curious as to what will be Mitsubishis answer with the Eclipses 260/260 powerplant and how they got that output. Whether it be MIVEC or DOHC or both. Hopefully the new world engines will offer the flexbility that Honda is so lauded for.
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From: Lakewood, CA
Originally Posted by MitsuRalliArt
Give me some forged titanium rods and pistons and I'll prove you wrong.
