"Heard of the old hemi?????"

Yeah, and it did flow well, but not as well as a modern 4 valve head can flow. The old SOHC 427 FE outflowed the old Hemi.

"Valves are valves, no matter how they are opened, they're still valves. A 2 valve engine is the same valve design as the standard OHV engine. It all depends on how big the manufacturer wants to make the valves. The difference is how the valves are opened. OHV has the crankshaft turn the cam, which moves the lifters, which moves the pushrods, which move the rocker arms, which push the valves open. OHC engines don't have to bother with lifters, rocker arms, or push rods. Less valve train weight means less rotating mass, means more efficient design."

I didn't go down that road with the argument, and I actually agree with that. Camshaft placement has very little (if anything) to do with power band. However, it is simpler and cheaper to have a DOHC running a multivalve head than it is to use a pushrod design. Think about the complexity of a multivalve Hemi with pushrods!!! DOHC engines could have hemispherical combustion chambers but that doesn't help flow, burn charcteristics, or power. The pent-roof is superior and that design has DOHC written all over it.

 

You sure about that? Besides, that doesn't support your multivalve argument at all since the SOHC 427's had 2 valve heads. I'd like to see the flow numbers for a SOHC 427 and a 426 Hemi off the same bench for comparison.

I've never seen a rear wheel dyno run from a Cobra R. What kind of power do they put down? My completely stock 04 Z06 made 359 HP 362 lb/ft with 600 miles on it a couple weeks ago for comparison.

 

The point about the 427 SOHC wasn't to compare the number of valves, it was just to say that the old Hemi wasn't the end-all be-all of flow.

Check out http://users.erols.com/srweiss/tablehdc.htm
The standard Hemi and the SOHC both flow 355 on the intake. The Hemi flowed 213 on the exhaust and the Ford 248. These were taken at .600 and 28" water.

These guys put down 366 to the rear wheels. I've heard of a few more in that area. The torque on those things is phenomenal as well.

http://www.50mustangandsuperfords.com/roadtests/18642/

 

Were the numbers on that table taken off the same flow bench? If not, then they are good "go by" numbers, but they really can't be compared. Flow numbers vary greatly from one bench to another, even on benches of the same make and model.

That R did make some good numbers. About the same as what I've seen well broken inn Z06's make. The fact remains though, that the 4 valve heads of the Ford don't really show any advantage over the LS6, and they are more expensive to boot.

 

wait a tick....

the SOHC 427 was a NASCAR engine only....it wasn't ever put in production vehicles....

 

Actually Mattsbox99, back at the time that that engine was to be used, NASCAR rules were somewhat like Trans Am in that the engines used had to be homogulated (sp) meaning that they had to be a readily available to the public "production" engine. I believe the minimum was 500 units or so but I could be incorrect. At any rate, it was put into production. Another interesting note, it was this engine and the Mopar Hemi that were the direct cause of the current displacement limit now enforced by NASCAR.

 

yes, only if the engine was used in NASCAR did it have to be put in production vehicles, but it wasn't the SOHC one, just the 427FE. and it was 500 units.

 

You're right that the SOCH 427 was never used in production vehicles, but it certainly wasn't a NASCAR only motor. Drag racing was where the vast majority of the 427 Cammers went, ending up in the 67 AFX Mustangs and many early Ford funny cars.

 

So, you're upset that the 5.7L LS6 is on the same field as the 5.4L DOHC Cobra? Seems like that. You are also negating the potential that each engine offers. The LS6, though a good stock engine, does not respond as well to modifications when compared to the 5.4L. Supercharge both of them and the Cobra engine will destroy the bowtie. Sorry, that's just the way it is.

 

What makes you think I'm upset? Actually, the fact is that even with it's 4V heads and "modern technology", the 5.4 DOHC is just about even with the "ancient" LS6 and it's 2V configuration. Acording to some here, 4V heads are the only way a motor can make power, and that is obviously not the case.

 

Z06's are hitting their max hp at about 800 RPM's higher that Cobra R's. Give the R a little bigger set of cams, so that it's power is 800 RPM's higher and it would smack a hairlip on the Z06.

Don't get me wrong, I love the new LS1's and LS6's. They are great engines. I think I'm going to put a LS1 in my Landcruiser. Great power, still have some torque too, and good mileage. All aluminum won't weigh me down, either. I really like them, I just think the modulars are even better, with even more power potential. Just because Ford won't use the power, doesn't mean it isn't available. I mean come on, look at the power that the R motor makes. Even down low. Hell, Dodge would call that a truck motor. The Hemi makes max hp at 5600. The R at 5400. The R has a lower RPM operating range than the Hemi and Ford puts it in a limited edition "race" car and Dodge puts their Hemi in everything. There's no reason why Ford couldn't do the same thing, if they wanted to.

 

I never said it was the "only" way. Just a better way, and ultimately you can potentially make more power than ANY 2 valve head. Simple physics, really.

 

Almost forgot. Give the R the extra 15 cubes and it would also smack down the Z06. When you are making over 1 hp per cube, that extra displacement would give the R almost 20 more hp right there. That in combo with the larger cams as mentioned above and it would be a pretty big gap between the two.

 

Yeah, then put the R heads on the Navigator and have it kick some Caddy booty.

 

The SOHC 427 was never used in NASCAR. It was banned from the beginning. GM and Chrysler both cried foul because of the expense to creat a competive engine angainst the SOHC.