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.

 

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?

 

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

 

In my opinion this is the best thing to come along for a IC engine in a LONG time. I would LOVE to run a set of these heads on a SBC.

 

this is what he said along with a flow sheet he sent to my dad and confirmation by nelson racing when i asked them about the heads....and they had no clue i have any affiliation with russ so they had no reason to fluff my pillow if ya know what i mean. it's really sad he works the way he does because like i said we could have sold many sets of SBC, SBF and a few BBC heads. we also had some ls heads in the works but like everything he works with he will lose track of it. those boat heads took for ******* ever for him to build. so many excuses and bullshit it actually was a main factor that our comapny is no more......company wasn't doing good anyway but that didnt help at all......either way the boat guy got a set of heads and should be doing something with them next year hopefully he enjoys them because he dropped some fat coin on them and delt with WAY to much bullshit. nothing worse than telling a customer sorry we dont know what the status on your heads are for a WHOLE YEAR!

 

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.

 

Too much technicalities! Engine component implementation, how does that sound? I can't call the Small Blcok Chevy a bad design, however, its component implementation is inferior.

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.

 

I take it your basing this on their, that is, GM's, two valve per cylinder, and prehistoric pushrod usage? I honestly wouldn't call it inferior, as for a fraction of the average "exotics" price, you get performance levels that are right there.

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.

It has been proven time and time again. Calloway's creation known as "Sledge Hammer", a TT C4 vette, utilizing the ancient small block chevy, is still one of the fastest top speed street car's today. Lingenfelter's TT C5 recorded 0-60 times of 1.97 seconds, running nine seconds flat in the quarter, completely street legal, with a very tame idle....

This all boils down to personal preferance though. I happen to like a throaty exhaust. But as for lower idles, and smoother runnings, I definitely don't agree. Between the camshaft technology that is being released today, as well as aftermarket head, intake, exhaust and ignition designs, a four valve head is not really necessary... other than to say, "I gots me a pair".

 

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.

 

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.