6 Valve Headcylinder

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HKS
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Awesome
I have seen 6 Valves but I have never seen 6 valves/cyl.
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mx_tifoso
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mep wrote:...You should try to arrange the valves completly symetrical.
What I mean is, that there is allways an intake valve, exhaust valve, intake valve.

So the cylinder could be filled ideal by the gas and so getting a more ideal combustion...
Maybe a bit OT....

Seeing how that would be an ideal arrangement, why don't manufacturers such as GM design their current engines like that? AFAIK, for the most part up until this year they still have 16 valves in [most of] their V8's, even Ford Motor Co. have 24 valve V8's!

I have been wondering about that for some time now, would someone be willing to expand on that please? Because if 3 valves per cylinder is a better design* in many ways, why don't manufacturers like GM implement it?

Thank you in advance.

*compared to 2 valves per cylinder.

PS. It would be best if there were no "everything American" hate posts. PLEASE!
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Ray
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I have yet to see, domestically, any benefit with more valves with similar displacement. Ford has their 4 valve Mustang engines, and their 3 valve truck engines, yet they don't make any more power or fuel economy as far as I can tell. They claim it flows better at the top end, and it does in certain cases. But a good LS1 doesn't need to. It makes it without doing all that revving. The biggest thing that shows me power wise, everything Dodge or Ford has that makes 500hp or more has either 2 extra cylinders, or a supercharger of some sort. They just can't make an engine that makes good power and economy like GM does. The new Hemi is junk too. A friend of mine has a truck with one. It's slower, less powerful and uses more gas than my little 4.8 Chevy. Not to mention they don't know how to make a decent reliable truck. Maybe now that Daimler has left and isn't hell bent on continuing to run that company as far underground as possible, they'll get back to actually making good products and money. Daimler really screwed that company up.

They make crap engines no matter how many valves they have. The only reason they use more valves is to try and make more power with less displacement, and in their case it doesn't work. It works in a Ferrari, or a Lambo, but not in the crap they make.


EDIT: In other words, they don't know how to make good cylinder heads. That's about as easy as you can sum it up. They suck, and they have always been behind Chevrolet/GM. An LS1/LS6/LS7 head is by far better than any domestic 3 or 4 valve head made by any competitor.

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Carlos
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Just contrasting 2 different V8's of similar size both built by General motors. one a 2 valve and the other a 4 valve.

Different designs for different vehicles at different price points. The LS1 at 4.8 liter produces about 255 horsepower with a V8 2 valve. It has a sort of heart shaped combustion chamber, each valve having a round surround, each area produces a swirling charge that is very efficent and makes very good horsepower, the valve size is also maximized as the valves are almost parallel. all aluminum, pushrods, cam in block 2 valves and very cheap to make. Makes power and torue about 4000>5000RPM with a bore about 4 inches.

GM also makes the Northstar, a 4valve, double overhead cam V8 of 4.6 Liters with a very shallow pentroof combustion chamber that breaths well because the 4 valves allow a little more valve area, it has a similar bore, about 3.5 inches and is also aluminum. It makes 290> about 350 horsepower and torque between 4500 and 6000RPM but less torque than the LS1.

The difference is the 4 valve engine is really expensive to build. Yes the LS1 could be tuned to make a similar amount of horsepower but the Northstar has higher design and horsepower possibilities. It was used in the IRL at about 690HP at 10500RPM with 4 liters displacement. A version of the motor was also used in the Le Mans Cadillacs around 2000.

The LS1 has a following of enthusiastic tuners and parts makers focusing on head and cam design and can be upgraded to produce , oh , probably 450hp for the street and more for track or drag strip.

Different production motors for differnt purposes at very different price points to build.

SZ
SZ
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Ray wrote:I have yet to see, domestically, any benefit with more valves with similar displacement. Ford has their 4 valve Mustang engines, and their 3 valve truck engines, yet they don't make any more power or fuel economy as far as I can tell. They claim it flows better at the top end, and it does in certain cases. But a good LS1 doesn't need to. It makes it without doing all that revving. The biggest thing that shows me power wise, everything Dodge or Ford has that makes 500hp or more has either 2 extra cylinders, or a supercharger of some sort. They just can't make an engine that makes good power and economy like GM does. The new Hemi is junk too. A friend of mine has a truck with one. It's slower, less powerful and uses more gas than my little 4.8 Chevy. Not to mention they don't know how to make a decent reliable truck. Maybe now that Daimler has left and isn't hell bent on continuing to run that company as far underground as possible, they'll get back to actually making good products and money. Daimler really screwed that company up.

They make crap engines no matter how many valves they have. The only reason they use more valves is to try and make more power with less displacement, and in their case it doesn't work. It works in a Ferrari, or a Lambo, but not in the crap they make.


EDIT: In other words, they don't know how to make good cylinder heads. That's about as easy as you can sum it up. They suck, and they have always been behind Chevrolet/GM. An LS1/LS6/LS7 head is by far better than any domestic 3 or 4 valve head made by any competitor.
i'm lost for words and can't quite find a shovel big enough.

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Ray
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SZ wrote:i'm lost for words and can't quite find a shovel big enough.
Calling Bulls*it are you?

Northstar engines are great, but they are more expensive and more complex. More things to break if you don't design them right. And GM has very few examples of a good 4 valve motor. I think it was the ZR1 Corvette that had one a few years back, and it was a dog. Comparing an IRL motor to a street variant isn't even a close comparison. That's a race motor, not a street motor. That's the same as me comparing the 7 second world record holding Trans Am for fastest LS1 street car in NA. Motors are of the same design as my truck motor, but nowhere near comparable.

4 valves aren't necessarily the answer, or the preferred option. All I hear in other cars sites forums is that American pushrod technology is crap, we are behind the Europeans in technology, the only way we can make power is with bigger engines. It's a regular hate America, and say that they are all bumbling backwards idiots.

Not true. Our engines are just fine thanks. They make good power and economy. They don't need 4 valves per cylinder. If it makes good power and fuel economy with 2, then what's the big deal?! Why are we inferior because we don't follow the Europeans in their car design? It's a non-issue with me. All this crap about, '"it's superior, it breathes better, it has more power potential", may be true in some cases. But flat out 2 valves per cylinder WILL get the job done for less cost, and possibly making more power. So what's the problem?

I work with a guy. He has a DOHC Mazda 3. Gushes over how much power it makes and how fun it is to drive. I've ridden in it, it is quite fun to squirt around in. But then talking about power in V8s versus I4s he made a grievous and typical 4 cylinder fan mistake. He said with his superior power per liter he had kept up with a Yamaha 600 motorcycle in a race. He's an outright liar. He always talks about how good 4 cylinder designs are superior and better, make more power per liter, blah blah blah. Then he goes and tells that lie. NO production car in the world will keep up with a 750cc motorcycle. Never, not gonna happen.

EDIT: I put Yamaha 600 then said that no car would beat a 750cc bike. Mistake. I meant to put 60cc bike.
Last edited by Ray on Fri Nov 09, 2007 10:34 pm, edited 1 time in total.

mahesh248
mahesh248
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I don't understand any of this m a second year engineering student , doing third now , why do they use more than 2 or 4 valves , whats the point , please explain.

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flynfrog
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Ray wrote:I have yet to see, domestically, any benefit with more valves with similar displacement. Ford has their 4 valve Mustang engines, and their 3 valve truck engines, yet they don't make any more power or fuel economy as far as I can tell. They claim it flows better at the top end, and it does in certain cases. But a good LS1 doesn't need to. It makes it without doing all that revving. The biggest thing that shows me power wise, everything Dodge or Ford has that makes 500hp or more has either 2 extra cylinders, or a supercharger of some sort. They just can't make an engine that makes good power and economy like GM does. The new Hemi is junk too. A friend of mine has a truck with one. It's slower, less powerful and uses more gas than my little 4.8 Chevy. Not to mention they don't know how to make a decent reliable truck. Maybe now that Daimler has left and isn't hell bent on continuing to run that company as far underground as possible, they'll get back to actually making good products and money. Daimler really screwed that company up.

They make crap engines no matter how many valves they have. The only reason they use more valves is to try and make more power with less displacement, and in their case it doesn't work. It works in a Ferrari, or a Lambo, but not in the crap they make.


EDIT: In other words, they don't know how to make good cylinder heads. That's about as easy as you can sum it up. They suck, and they have always been behind Chevrolet/GM. An LS1/LS6/LS7 head is by far better than any domestic 3 or 4 valve head made by any competitor.
instead of comparing truck engies to car engines to weed wackers. why not compare the same engine with 2 and 4 valve heads.

the ford 4.6 liter modular motor would be a good starting point

2V police interceptor out of the crown vic
250 hp (186 kW) @ 5000 rpm / 297 ft·lbf (403 N·m). @ 4000 rpm/9.6:1 compression - 4.6 L V8 (Police Interceptor only)[3]

DOHC 32-valve 4.6L V8, rated at 280 hp, came with a distributorless coil-on-plug ignition system, eliminating the use of high voltage spark plug wires. Some of the transmission internal parts were reinforced in the late 1997 models and all 1998 models. LSC models had firmer shocks and larger anti-roll stabilizer bars, for better handling and control, a lower gear ratio and true dual exhaust giving a 10 hp boost taking it to 290 hp


Engine : V8, OHV('94-'95) / DOHC('96-'98), front engine RWD
Displacement : 4,949 cc('94-'95), 4,605 cc('96-'98)
Valve : 16 valves, 2 valves per cylinder('94-'95)
32 valves, 4 valves per cylinder('96-'98)
Transmission : 5-spd manual
Fuel economy : city - 16 mpg('94-'95, estimated), 18 mpg('96-'98)
highway - 24 mpg('94-'95, estimated), 26 mpg('96-'98)

Horsepower : 240 hp @ 4800 rpm('94-'95), 305 hp @ 5800 rpm('96-'98)
Torque : 285 lb-ft @ 4000 rpm('94-'95), 300 lb-ft @ 4800 rpm('96-'98)
0-60 mph : 6.3 sec.('94-'95), 5.8 sec.('96-'98)




a little hard to read but basically the 4v engine makes 30-50 more hp in stock form. More gains are to be made in forced induction.

And valve heads do flow better than 2 valve heads there is no question here its simple physics.

Useing the ford 4.6 agin

the 4 valve has two 37mm intake valves to reach 4.57 in^2 of curtain area they need to open .500 inches

to match this with the 2 valve engine with its one 45mm valve you need to open it .812 inches

thats not going to happen in most engines with out some contact

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Ray
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What year models are you talking about for each engine.

An example of why I asked that question.

LT1
92 LT1 Y-bodies were rated at 300 hp (220 kW) and 330 ft·lbf (447 N·m)
96 LT1 Y-bodies were rated at 300 hp (220 kW) and 340 ft·lbf (461 N·m)
93-95 F-bodies were rated at 275 hp (202 kW) and 325 ft·lbf (439 Nm)
96-97 cars were rated at 285 hp (210 kW) and 335 ft·lbf (452 Nm)

Same engine, yet vastly different power ratings. I know the argument of 2 versus 4 doesn't apply here, but there are revisions and improvements on one engine design alone that vary alot from one to the other.

Another example.

LS1

all-aluminum 5.7 L (346 in³) pushrod engine and was rated between 305 - 350 hp (227 to 261 kW) and 335-365 ft·lbf (454-494 N·m) of torque

Yes larger displacement. That has a bit to do with it. But it makes about 25 to 75 more horsepower.

LS6

The initial 2001 LS6 produced 385 hp (287 kW) and 385 ft·lbf (522 N·m),but the engine was modified for 2002 through 2004 to produce 405 hp (302 kW) and 400 ft·lbf (542 N·m) of torque. The LS6 shares its basic block architecture with the GM LS1 engine, but other changes were made to the design such as windows cast into the block between cylinders, improved main web strength, an intake manifold and MAF-sensor with higher flow, a camshaft with higher lift and more duration, a higher compression ratio and a revised oiling system better suited to high lateral acceleration.

Same displacement, yet alot more power. Modifications were made to improve the power.

Yet it still outperforms the DOHC Ford motor with only a moderate amount of extra displacement. I'll take my two valves over four. Less complicated, cheaper, and just as efficient.

PLUS, I'm positive that those engines were not the same design. If they were the same block, heads, ignition, camshaft durations, lift, and so forth just that one had 4 valves and not 2, then you can make a direct comparison.

Oh, and might I add that the Global Motorsport Engine of the Year for 2006 was ...................the LS7.R A lowly pushrod engine. Wow. Never saw that coming. http://www.americanlemans.com/News/Article.aspx?ID=2724

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Ray
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Forget everything I said. You want a simple explanation as to why the 4 valve motor made more power than the Crown Victoria motor did? It's the MUSTANG. They would never ever in a million years let a fat old person car have more horsepower. And 30-50 horsepower over a fat old person car in your 'performance' car is quite sad. I would think Ford would make at least 300 hp in the flagship performance car in their lineup. At the wheels, not the flywheel.

I have yet to see a 4 valve motor make 7000-8000 hp like a Top Fuel motor either. When they do, I'll shut my mouth.

SZ
SZ
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"our" engines?

ray... can you spot an insecurity complex? seriously?

i go to auto conferences in detroit with engineers from all over the world, and the dinner table conversation between the engineers involved is NOTHING like this. mind you these are the guys designing and developing the very products you're talking about.

it's really simple mate. a product has a design brief. it has to hit certain performance targets, it has to be manufactured within certain critera, it has a certain project cost and timeline, it has a target unit cost.

(it has marketing criteria to meet too - i'd not be surprised if a two valve head was in the design criteria just to keep you and others like you pacified.)

to hit LS1's targets, a four valve head wasn't necessary. that's it. period. may not even have been a consideration given size, cost and marketing constraints.

i'll suggest some performance targets - a v8 needs to product torque. it doesn't matter what heads you stick on it, you need displacement and relatively easy porting. you need a certain bore to stroke ratio to increase the moment arm about the crankshaft on each conbustion pulse. power is the rate at which that torque is created, so higher engine speeds, for which you need a reciprocating assembly that'll hold together, and the ability to flow more air and burn more fuel. when you're at these bore sizes and not chasing insane power, you can still do that with a single inlet valve. it's not rocket science.

if you want more power definitively the single biggest impediment to getting air in is physically at the intake valves. you want more area, and beyond a certain size you can't do this with a single intake valve. so you have two. there are other considerations but we typically don't see diminishing returns until 4 intake valves. you have more air, and that's great, but there's a lot else involved in engine design to make sure you can turn a reciprocating assembly quickly enough to choke those valves and make more power.

there are many other reasons too for a multi-valve configuration, as there are many other reasons why a multi-valve street engine might not make a significant amount of power. so what. stick to the physics.

or name any capacity restricted formula where engine development is contested and RPM are either unlimited or stratospheric and show me where there's a leader running a 2V head. anywhere. haven't seen one in motogp, F1, whatever anywhere. nor have i seen a small capacity street engine with a 2V head in donkey's years.

i don't want to entertain and argument or any further insecurity... it's basic physics FFS.

"have yet to see a 4 valve motor make 7000-8000 hp like a Top Fuel motor either. When they do, I'll shut my mouth." - why don't you try and quantify/deconstruct that statement? there are good reasons why top fuellers are two valve engines - nothing to do with performance.

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Ray
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SZ wrote:"our" engines?

ray... can you spot an insecurity complex? seriously?
Forgive me, but I don't follow. I may be missing it completely cause I can be quite dense.
SZ wrote: or name any capacity restricted formula where engine development is contested and RPM are either unlimited or stratospheric and show me where there's a leader running a 2V head. anywhere. haven't seen one in motogp, F1, whatever anywhere. nor have i seen a small capacity street engine with a 2V head in donkey's years.


Exactly! I agree with you totally. Just because a larger displacement engine doesn't have more than 2 valves doesn't make it wrong. The reason small displacement engines have more than 2 valves is the fact they have to spin higher to make more power, and pushrods aren't a really good idea when you turn and engine 10k. They need those extra valves to flow air that turning that high. Regular run of the mill V-8s don't have to do that.
SZ wrote:"have yet to see a 4 valve motor make 7000-8000 hp like a Top Fuel motor either. When they do, I'll shut my mouth." - why don't you try and quantify/deconstruct that statement? there are good reasons why top fuellers are two valve engines - nothing to do with performance.
Okay, here goes. Just like your challenge to find a CID restricted formula using two valves, Top Fuel engines are restricted to two valves per cylinder. I have yet to see ANY other engine with ANY number of valves greater than two make the power levels that they do.
flynfrog wrote:a little hard to read but basically the 4v engine makes 30-50 more hp in stock form. More gains are to be made in forced induction.
Sorry to drag you into this rebuttal flynfrog. This further advances my argument. 4 valves don't necessarily make more power, forced induction or not. The comparison of a Crown Vic motor, and the same engine in a Mustang isn't completely across the board even. Ford, nor any other car maker, would allow the Mustang to be lower in power and torque than even a specialty package on a police car. Now I didn't go research every carmakers police car hp ratings compared to performance car ratings, but I wouldn't do it.

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Carlos
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Well mahesh248 - I knew a fisticuffs was going to break out so I went to take a nap and fortify my energy. I'm quite well rested after my nap, thank you. Generally speaking, you want the largest valves with the largest open area to get as much air/fuel in and out of an engine as best possible and at the same time have it burn properly, completely to get the most power. There are many many reasons why 2 valves, 3 valves and 4 valves are best, best for a given situation. What do you want? Power. Economy. Low Emissions. Complexity and What About Production Cost? My head aches mummy. Several manufacturers have built engines with 5 or more valves but generally everyone agrees it's to much trouble, too complex, too expensive, good grief, the engineers have do to fancy calculations for frictional losses and air flow and mould makers have to make complicated stuff and its just to much work and we're not being paid enough and they won't build it anyway so I'm leaving my desk to take a nap in the john.(Sigh) Well make up your mind; what do you want? Kind of like the first time I order Thai take away. (Sigh) :wink:

I was going to post 6 or 7 pictures but you know how you sometimes feel more drowsy after a nap than before? That's how I feel. Besides I take a long time to post pictures, plus it's Friday night and I'm expected to go out and drink myself s :wink: :wink: tfaced. It's a cultural norm and who am I to disagree? ... 2 valves can be great, very simple too, but you can only make them so big before they are so heavy the motor won't rev very fast and the valves almost touch and there's so much space left in the combustion chamber if only someone would pay for more valves and the combustion chamber is a funny shape and the gas and air won't burn and the intake ports are so huge air flows at a crawl and wouldn't it be nice if someone would pay for more valves and with 2 huge valves where do we put the spark plug so everything burns well and we can't get a high enough compression ratio to make Carlos happy and I have a headache mummy. :wink:

You can build a 3 valve head, usually 2 intakes and 1 exhaust with a single overhead cam a funny looking, heavy forked rocker arm and a skinny one pushing the exhaust valve up and down and now we have a siamesed intake port with messes intake acoustic tuning and the exhaust valve is still heavy and we still have area in this narrow angle pentroof combustion chamber and what we really want to do is build a 4 valve head anyway because it's so cool. Why? Well 4 valves maximize intake area in the combustion chamber, gives a good location in the middle for a sparky so the bang, known as flame propagation is even and very quick and makes lots of horsepower and the compression ratio is really high and stuff flows in and out of the cylinder at maximum speed and efficency and we can sort of tune the intake and exhaust ports acoustically even if they are siamesed and we have a seductive valve train without rockers but with double overhead cams and Carlos is happy because he thinks this is the best design although not quite sure satisfied because he thinks each valve should have a separate port and no one else does and yes (Sigh) I'm starting to get a headache mummy. I've written enough and it's my obligation to go to the neighbourhood haunt and drink even though Alcool is not a favourite and the 60's left me with other preferences for substances that only a chemistry set can satisfy. (Sigh) That may explain my extremely limited attention span and why I have a headache mummy :wink:

mahesh248 - Some links that help explain stuff
http://www.secondchancegarage.com/public/585.cfm
http://www.highperformancepontiac.com/t ... index.html
http://www.highperformancepontiac.com/t ... to_18.html
http://www.datsuns.com/Tech/ohv_vs_ohc.htm
http://en.wikipedia.org/wiki/Multi-valve
http://g-speed.com/pbh/cylinder-head-tech.html
http://www.billzilla.org/2v4vpage2.htm

OT-mahesh248-TC? - Slipper clutch

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flynfrog
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Ray wrote:
flynfrog wrote:a little hard to read but basically the 4v engine makes 30-50 more hp in stock form. More gains are to be made in forced induction.
Sorry to drag you into this rebuttal flynfrog. This further advances my argument. 4 valves don't necessarily make more power, forced induction or not. The comparison of a Crown Vic motor, and the same engine in a Mustang isn't completely across the board even. Ford, nor any other car maker, would allow the Mustang to be lower in power and torque than even a specialty package on a police car. Now I didn't go research every carmakers police car hp ratings compared to performance car ratings, but I wouldn't do it.
they are not the same engine but they are close bore and stroke wise and i picked the cop car version from 2005 since it was the highest HP in the 2v and compared it to the mark viii engine and the mustang both of which make more power.

And you are correct that you don't need 4vs to make more power but all things equal a 4v head will flow more and rev higher than a 2v motor the valves don't have to open as far to get the same flow

SZ
SZ
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ray, it'll have as many valves as the design brief requires it to, and those requirements can be as diverse as emissions, driveability, outright power, manufacturing cost, modularity, marketing rationale, whatever.

plenty of people stateside that'd revolt if the next generation GM small block had 4 valve heads, or if you tell them the bleeding edge of motorcycling technology isn't normally within 10km of a harley.

the reason any engine has more valves is to flow more air/intake charge. period. if your engine doesn't need to for it's design targets, it won't. conversely if you have a bore size allowing certain valve sizes and certain max lift and you need that engine to develop more power than what intake charge it can flow, you're not going to bend physics to suit any time soon.

you max out development on an engine with a two valve head for power to the point the valve size becomes the limitation on power, and a four valve head will make more. every time. that's basic physics.

power is far from the full story behind any modern engine's performance targets - you use full power often enough for it to be a marketing statistic most of the time - and in that, there are plenty of reasons to go multi-valve.

i still nearly piss myself laughing when people bring top fuel dragsters into an engine development conversation as if the most power is the last word in valve count. that's bullshit.

there is so much - as you likely well know - that's needed to make a top fueller go as quickly as they do. chassis design, all manner of traction issues, clutch engagement vs. heat, driver reactions, fuel characteristics... even if there were a readily available 4 valve head that was available for use (there isn't), you'd be very likely traction limited/clutch heat limited regardless. so a silly argument.