Benefits of a 32 valve heads
#101
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Well any 12 cylinder has the advantage of natural balance, not to mention that engine's displacement is probably pretty high, and it doesn't have to turn high RPMs to get power.
But slap 4 valve heads on it and see what happens. I'm not saying exotics are superior, I'm saying their engine design is. You can't beat the flow offered by 4 valve heads.
But slap 4 valve heads on it and see what happens. I'm not saying exotics are superior, I'm saying their engine design is. You can't beat the flow offered by 4 valve heads.
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Originally Posted by FieroZ34
I'm not saying exotics are superior, I'm saying their engine design is. You can't beat the flow offered by 4 valve heads.
#103
HAHAHAHAHAHAHAHHA you have to love talking about fuel cunsumption of a 5.7ltr V8! hehe
this is the main reason why big American V8 have never really made it in Eurpo. fuel in england at the moment is around £1 per ltr (about $1.8 per ltr). now if you want to talk abut fuel consumption lets talk about a nice 1.3ltr turbo diesel thats doing about 50mpg!
now if your talking about power!!!!
thanks Chris
this is the main reason why big American V8 have never really made it in Eurpo. fuel in england at the moment is around £1 per ltr (about $1.8 per ltr). now if you want to talk abut fuel consumption lets talk about a nice 1.3ltr turbo diesel thats doing about 50mpg!
now if your talking about power!!!!
thanks Chris
#104
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Originally Posted by Cobra20
Here is something for you guys to chew on
http://www.coatesengine.com/csrv.html
how is that for a head??
http://www.coatesengine.com/csrv.html
how is that for a head??
#105
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Originally Posted by MadSpeed
Have you personally seen these alegded flow numbers?
He is also know for his exageration abillitys as well
I personally watched him dyno a VW 1835 he claimed made 250 hp + it was N/A btw
and the next day we heard it seize on the dyno from next door (we had a nice chuckle)
He is also know for his exageration abillitys as well
I personally watched him dyno a VW 1835 he claimed made 250 hp + it was N/A btw
and the next day we heard it seize on the dyno from next door (we had a nice chuckle)
#106
A few facts: It is a myth that OHC/DOHC motors are peaky high rpm performers. Just as with any motor, the intended powerband of a DOHC arrives from the sum of quite a few variables--static C/R, intake runner length, valve/seat size, port sizes, etc. The real advantage of a 4v motor vs. an all else equal 2v is the fact that they don't require large cams to make high rpm power--and because of this the powerbands of 4Vs tend to be much longer than those of 2vs--remember, a longer powerband is more avg HP/TQ. This is due to the massive valve curtain area that 4Vs fill the cylinders with, and the outstanding velocity that 4 valves afford. Large cams are simply unecessary, you'll rarely if ever see a 4v with anything larger than .500" lift, if you do it's more for ramp rate/angle than anything else. 2Vs fill via ram tuning/inertia filling, requiring lots of lift/duration to get a large mass of air moving into the chamber. Take two quality heads, one 2v one 4v, that both flow the same peak #s and the 4V will dominate at low/midrange lift, exhaust flow isn't even comparable (unported a Ford GT/GT500/R head will flow 260cfm @ .500" lift, after porting 290-310cfm @ .500" lift on a 3.57" bore with measely 32mm exh valves) which is why turbos love 4 valves, and velocity will be around double that of the 2V.
Essentially, a 10,000rpm pushrod would be far "peakier" than a 10,000rpm 4v--the Tymensky's old big bore 305CI/4v ran through the traps at 10,000rpm, made peak at 9200rpm, and idled at ~1400rpm.
We should all pray for a state of the art, large displacement & bore (which Modulars lack, limiting valve/seat size and ultimately limiting power) 4v V8 from GM. I'd be a convert for life.
Regarding Ford GT/GT500/R heads vs. LS7s...
On a 3.57" bore (.020" over 4.6 or 5.4) unported GT heads flow around 305-310cfm@.500" intake and 255-260cfm @ .500" exhaust. After porting they're around 350-370cfm @ .500"/290-310cfm. This is with tiny (relative to what they should be for motors of this displacement) 37/32mm valves. Just imagine what would happen with a 4"-4.125" bore.
Essentially, a 10,000rpm pushrod would be far "peakier" than a 10,000rpm 4v--the Tymensky's old big bore 305CI/4v ran through the traps at 10,000rpm, made peak at 9200rpm, and idled at ~1400rpm.
We should all pray for a state of the art, large displacement & bore (which Modulars lack, limiting valve/seat size and ultimately limiting power) 4v V8 from GM. I'd be a convert for life.
Regarding Ford GT/GT500/R heads vs. LS7s...
On a 3.57" bore (.020" over 4.6 or 5.4) unported GT heads flow around 305-310cfm@.500" intake and 255-260cfm @ .500" exhaust. After porting they're around 350-370cfm @ .500"/290-310cfm. This is with tiny (relative to what they should be for motors of this displacement) 37/32mm valves. Just imagine what would happen with a 4"-4.125" bore.
Last edited by GotStroke?; 07-21-2006 at 02:12 AM.
#107
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Originally Posted by Street Lethal
Engine design being superior in what respect though? Having better gas mileage? Better computer controlled precision? Better dyno numbers? I mean, if your into bragging rights, and/or pissing contests, then by all means, go with those Dominion/Aero heads. How much faster do you think your honestly going to run in the quarter mile though?
As the guy above me stated in a nutshell, flow! Most foreign exotics utilize 4v heads. They get better gas mileage, make more power, have wide torque curves, yada yada yada. Yes they have the advantage of amazing EFI systems that have seperate real time fuel trims PER CYLINDER, but that is again better components. As for the 1/4mi, that's where it gets gray. You can run as fast as any human could ever want with 2 valves, this has been proven. But for a daily driven car, with say 600hp, the 4v heads will enable the engine to drive and act MUCH nicer. Lower idle, smoother running, quieter, etc.
As for the decent DOHC 32v engine, it will take time. Cadillac has got the best engine GM makes, which is of course the Northstar. (Slight bias there..) With some more displacement, that engine would be everything the 7.0l LS7 is and SO much more. Hell $2500 at CHRF will bring a N* on the verge of 1hp/l.
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Originally Posted by FieroZ34
I can't call the Small Blcok Chevy a bad design, however, its component implementation is inferior...
Also, let's not give all the credit to the "engine" design of the exotic, as vehicle weight (not necessarily total weight, but where the weight is positioned on the vehicle), suspension, TRANSMISSION GEARING.... all come into play as far as their unrivaled(?) performance.
Originally Posted by FieroZ34
You can run as fast as any human could ever want with 2 valves, this has been proven.
Originally Posted by FieroZ34
But for a daily driven car, with say 600hp, the 4v heads will enable the engine to drive and act MUCH nicer. Lower idle, smoother running, quieter, etc.
#109
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I will not say they are necessary, they obviously aren't. But because of the unrivaled flow and spark advantage, you can use tamer parts elseware, including the cam. Is it superior for racing, maybe not because you can deal with poor drivability at the track. But in a street vehicle, the design can't be beat.
I shouldn't say exotics like I do, more should say companies using advanced 4v design (Honda, Nissan, etc). The exotics just have the funding to take it one step further, not in specific output, but in total output.
When I was younger, an engine builder I knew said this: "If you want to know what's best, pull the fairings off a GSX-R once a year." I can't argue.
I shouldn't say exotics like I do, more should say companies using advanced 4v design (Honda, Nissan, etc). The exotics just have the funding to take it one step further, not in specific output, but in total output.
When I was younger, an engine builder I knew said this: "If you want to know what's best, pull the fairings off a GSX-R once a year." I can't argue.
#110
Once again, in an engine you care about the following:
Weight
Size ( Dimensions )
Fuel Mileage
Power output
is it noisy or not?
Is it supportable ( IE you can get parts for it )
Who cares if it is a 4.5L motor with 4V per cyllinder DOHC making 375HP and 22 MPG on highway, taking up 10 cubic feet of space, that weights 620LB
or a 7.0L motor using pushrods, making 520hp and 28 MPG on highway, taking up 8 cubic feet of space, that weights 450LB?
you see what Im saying. Its about what goes in, what goes out and the weight.
Weight
Size ( Dimensions )
Fuel Mileage
Power output
is it noisy or not?
Is it supportable ( IE you can get parts for it )
Who cares if it is a 4.5L motor with 4V per cyllinder DOHC making 375HP and 22 MPG on highway, taking up 10 cubic feet of space, that weights 620LB
or a 7.0L motor using pushrods, making 520hp and 28 MPG on highway, taking up 8 cubic feet of space, that weights 450LB?
you see what Im saying. Its about what goes in, what goes out and the weight.