4-valve v's 2-valve heads

[oldcorollas]

how is your formula 1 team going?

good mate, just need to put on the finishing touches :D sponsor stickers and whatnot...

then glue on the wheels...
(and i stupidly chose to go for turbines instead of F1 :p)



oh, Harley does have a twincam... 1.6L, 124nm (TC96)... hardly inspiring stuff and probabyl not a fair compairson

sure everyone likes value.. but if you want power per dollar.. just make it 7L or 8L or 9L, use cheaper chinese parts... throw the engine away earlier.. change parts when they break... no real secret to bigger engines making more torques

[Dave]

good mate, just need to put on the finishing touches :D sponsor stickers and whatnot...

then glue on the wheels...
(and i stupidly chose to go for turbines instead of F1 :p)



oh, Harley does have a twincam... 1.6L, 124nm (TC96)... hardly inspiring stuff and probabyl not a fair compairson

sure everyone likes value.. but if you want power per dollar.. just make it 7L or 8L or 9L, use cheaper chinese parts... throw the engine away earlier.. change parts when they break... no real secret to bigger engines making more torques

as long as it keeps running, is not too heavy, does not use too much fuel I wouldn't give a fuck if my engine was 14 litres and the valves were actuated by the souls of murdered kittens

[oldcorollas]

how heavy is too heavy?
how much fuel is too much?

"as long as it keeps running, is not too heavy, does not use too much fuel"

sounds like the requirements of a taxi or truck engine.... no aspirations of performance?
what if your chosen engine could give better oomph in same size and weight, plus better drivability and use less fuel?

[Nero]

LSx series of engines are very good. It is staggering that they get the clean burn from such antiquated tech...but that is what GM are good at. The engine is clearly successful...it makes money and is cheap to make and suits the local market. Where I building a car that needed power then I would consider one, I did for Godiva!

[Billzilla]

no, because a side valve engine wouldn't make a decent amount of power without spending a bucket load and it being heavy and shit. Do you think I am that retarded that I don't realise that for a given application a 4v is going to produce more power, but what you fail to see is that it isn't the only way of filling the design brief that the LS1 does, a cheap to build, simple v8 engine that makes plenty of power. Why are you so one eyed that you don't accept that an LS1 does what it does well. Why don't you go back to engine analyser and build another imaginary engine that tries to prove a point despite nobody really caring, there seems to be a shitload of people that are more than happy with the engine.

Yes Dave, you are retarded.
I have said many times that I think the LS series makes good power for what it is.
People seem to make it a habit to miss-quote me, I don't know why.

My other thread was just a thought exercise, to see what an LS7 would be capable of in the same level of road-trim, but if given a really good pair of 4V heads. As it turned out, it was about another 200hp. You decided to try to trash that thread.
This thread is about finding out the flow figures of 2V & 4V heads on big engines, and again you are trying to trash it.

Don't shift the goal posts, you are simply wrong.

[HSV Senator]

Wow this has been done to death by the same people. I am no expert but this is my take on it.

Basically GM had a power and torque figure in mind when they designed the LS series motors. They would also know that the engine needed to be a specific size and weight to fit in the Corvette, obviously this has less relevance for any of the other cars the LS series is fitted to. They built an engine with all alloy construction, good flowing heads 6 bolt mains etc.

It made the power they require for the cars it is meant to be fitted to, its lightweight, has small packaging, its strong and powerful while keeping manufacturing costs low as of course GM would have had a budget for what each engine should cost them. So yes they managed to achieve their goals without using quad cams etc.

However anyone suggesting these are throw away engines with cheap parts is speaking out of their arse and needs to do some more research and maybe actually drive one of these cars. The materials or construction are not "cheap" and it probably costs a similar amount to many other motors to produce. However it makes alot more power.

They are a strong motor that can take alot of abuse, make excellent power and are smooth and relatively efficient. It meets emissions despite its capacity. Not wanting to come across as Ford bashing but look at the goals I have mentioned and then look at what the Ford 5.4 DOHC motor has ended up being.

GM could have built a quad cam motor, they have built a V8 Quad Cam Corvette before but the LS series meets the same requirements with no packaging issues and makes alot more power. So I think it is a good thing despite "only" being a pushrod motor.

I await the flame fest :O

[Billzilla]

GM could have built a quad cam motor, they have built a V8 Quad Cam Corvette before but the LS series meets the same requirements with no packaging issues and makes alot more power.

They do now, but not back in the day ->

According to Wikipedia, the L98 V8 it was competing with in the same chassis made only 300hp, compared to the ZR1's 375. Later models of the ZR1 were 405hp while the 2V variants were only 340hp.
It wasn't until about ten years later that they had a 2V engine that made more power - The 430hp LS3 which is 6.2 litres compared to the ZR1's 5.7 litres.
Suffice to say, given the advances made in the last decade plus, something much better than only 405hp could easily be done.

[TK]

Ok, here ya go Bill.

Heavily ported MY99 WRX heads, but not quite to the limit V's AFR 215cc intake CNC ported SBC ally heads:

In
Lift WRX AFR
.1 93.5 na
.2 186 150
.3 265.5 220
.4 300 276
.5 308 308
.6 na 315
.7 na 325

Ex
Lift WRX AFR
.1 95 na
.2 166 112
.3 213 150
.4 231 190
.5 235 207
.6 na 220
.7 na 230

As you can see the WRX heads are well in front up to .4" lift, which is close to their max lift, after which the AFR's catch up.
If you factor in that the AFR heads would normally be used with a roller cam with lift of at least .650" & very rapid lift rate (faster than OHC bucket & shim) you can see that the AFR's, in their intended role, are easily the equal of the WRX heads in terms of potential power production.

It should be noted that the WRX heads are HEAVILY ported & getting close to the limit, they were also set up to go on a 2.5sti block with 99.5mm bore (3.92").

Arguing that a 4-valve is always better is kinda stupid, a pair of V8 heads has under 100 parts, 4V V8 heads would have 300+ parts - they would cost more than double the 2V heads to make, then add the cost of driving all the cams etc.
All that for a minor benefit & at the cost of a much bulkier, heavier, more expensive & more complicated (& therefore more prone to problems) engine that barely produces any more power or uses any less fuel.

When will you 4V knuckleheads be able to admit that a well designed 2V head is capable of holding it's own when compared to a similar use 4V head?

There are without doubt many benefit of a 4-valve head on engines of smaller capacity, but for larger, lower revving engines there is almost no benefit.

What was the rpm that your 32v LSx engine made peak power at Bill? - how long do you think an engine of that capacity would remain reliable at those rpm?

[Billzilla]

Ok, here ya go Bill.

Heavily ported MY99 WRX heads, but not quite to the limit V's AFR 215cc intake CNC ported SBC ally heads:

In
Lift WRX AFR
.1 93.5 na
.2 186 150
.3 265.5 220
.4 300 276
.5 308 308
.6 na 315
.7 na 325

Ex
Lift WRX AFR
.1 95 na
.2 166 112
.3 213 150
.4 231 190
.5 235 207
.6 na 220
.7 na 230

As you can see the WRX heads are well in front up to .4" lift, which is close to their max lift, after which the AFR's catch up.
If you factor in that the AFR heads would normally be used with a roller cam with lift of at least .650" & very rapid lift rate (faster than OHC bucket & shim) you can see that the AFR's, in their intended role, are easily the equal of the WRX heads in terms of potential power production.

It should be noted that the WRX heads are HEAVILY ported & getting close to the limit, they were also set up to go on a 2.5sti block with 99.5mm bore (3.92").

What do you mean by heavily ported?
Have you worked out the correct average diameter to get the optimum average flow rate? Or just made them as big as possible?
This is the common trap - People seem to think bigger is better when it comes to porting and that's often wrong.
I'm not saying you've done that, just asking if you've done the calculations to make sure you've got it right.

Arguing that a 4-valve is always better is kinda stupid, a pair of V8 heads has under 100 parts, 4V V8 heads would have 300+ parts - they would cost more than double the 2V heads to make, then add the cost of driving all the cams etc.

I'm sorry but a good 4V head WILL always be better than a 2V head. It's just not possible to make a 2V head work as well as a 4V.
You're also quite wrong with the number of parts; yes there's twice the number of valves but the valve gear is far less complex. If you take into account the fiddling little bits of roller rockers, roller followers, etc, then there's quite likely less parts in a 4V head/engine.
I already worked out a rough cost as being about $1650 or so more, and demonstrated how much more power could be made and it was pretty good value to get that extra ~200hp.

All that for a minor benefit & at the cost of a much bulkier, heavier, more expensive & more complicated (& therefore more prone to problems) engine that barely produces any more power or uses any less fuel.

I again have already shown that if they were done properly the heads would not be much larger, and the extra weight is negliable compared to the extra power increase.
And sorry but you're simply wrong about not having much extra power. It's been demonstrated time after time with many engines. And no, I'm not talking about crappy engines like the Ford 5.4 litre contraption, but a properly built one. Because there doesn't seem to be any out there, people assume that it can't be done and that's a shame, or they (as is frequently done here) use example of poor 4V engines, despite being told many times how wrong that is.

When will you 4V knuckleheads be able to admit that a well designed 2V head is capable of holding it's own when compared to a similar use 4V head?

That is demonstrably totally wrong.
Again I use the example of the Sports 1300 engines - two engines the same capacity built to do exactly the same job.
The 3K Toyota engines made about 135hp for a good one (the really expensive and unreliable ones up around 145hp). The Suzuki when it was introduced also made about 135hp, but with some big restrictions.
The 3K had to be revved to around 9,000rpm, the Suzuki was limited to 8,000rpm.
The 3K needed 12.5:1 compression, the Suzuki is limited to 10.2:1.
The 3K needed a 320° 0.450" lift cam, the Suzuki is limite to ~275° 0.355" lift.
The 3K headed cost something like $1500 to get prepped, the Suzuki around $500.
The 3K needed to be rebuilt every year, the Suzuki runs for up to five years between rebuilds. A lot of internals in the 3K also needed replacing after certain intervals, the Suzuki often just needs a set of rings and maybe bearings.

I know it's a comparison of racing engines, but it's an example of how massivly wrong the "2V engines are as good a 4V ones are" thing is. Seriously wrong.

There are without doubt many benefit of a 4-valve head on engines of smaller capacity, but for larger, lower revving engines there is almost no benefit.

With no real examples of a big 4V engine we can only guess. I've got a lot of experience with the 4V heads and getting good power from them, someone give me a Nissan VK56DE and I'll build something very scary for you.

What was the rpm that your 32v LSx engine made peak power at Bill? - how long do you think an engine of that capacity would remain reliable at those rpm?

Far more than a push-rod engine would, as the valve gear is far more reliable in a cam-on-bucket head. Sorry Tony, but that is the argument of the ignorant.

[TK]

Bill - yours are arguments of the ignorant, you cannot see past the on-paper advantages of a 4-valve design to see that in the real world for larger bore engines they do not offer any significant advantages.

The WRX heads are not my best set - but are still better than just about anything else available in Aus, they are lineball with the megabuck Cosworth & Cobb tuning CNC heads - I have ported 70+ sets of these things, no-one has personally had more experience with porting them that I know of, the only heads available that flow more are heads with much larger valves requiring oversize seats - those heads use stock seats with 1mm oversize valves.

I just haven't got time to refute all of your arguments - I've got engines to build & heads to port (both 4V & 2V).
So I'll just say that your experience is limited to smaller capacity engines & what works with them, I play with a wide range of engine types on a daily basis - I know for a fact that a well designed 2V head used on a large bore production type engine is the equal of a similar engine equipt with 4V heads.
We are not talking exotics here, there is no point comparing a 5.7L 2V pushrod engine that does it's best work under 6000rpm to a megabuck 4V quad cam V8 that revs to 9000rpm - the average performance enthusiast could not afford such an engine, even if it was readily available.
The internal forces acting on such a large capacity engine revving that high make it necessary to use expensive forged internals & even then life span is limited - you just cannot rev a big engine that hard on a regular basis & have it live a long time.
The joy of a large capacity 2V engine is the stump pulling torque & throttle response - fitting 4V heads & making it rev to the moon would make them peaky, gutless at low rpm oversize copies of a DOHC 4-banger - everything us bogans hate.

[The Pupat]

Good-performance-for-the-price-forums

Last time I checked even the big spenders on this forum like edo still have a budget to build stuff, so sh!t like that is important.

[TK]

BTW - the intake ports of the WRX heads are barely larger than stock - the only metal removal is for the purpose of smoothing/blending, velocity is near identical to stock. The flow comes from near perfect bowl/short turn/seat/chamber design - my own design.
Grab your die grinder & see if you can beat it.

[Dave]

Bill - yours are arguments of the ignorant, you cannot see past the on-paper advantages of a 4-valve design to see that in the real world for larger bore engines they do not offer any significant advantages.

The WRX heads are not my best set - but are still better than just about anything else available in Aus, they are lineball with the megabuck Cosworth & Cobb tuning CNC heads - I have ported 70+ sets of these things, no-one has personally had more experience with porting them that I know of, the only heads available that flow more are heads with much larger valves requiring oversize seats - those heads use stock seats with 1mm oversize valves.

I just haven't got time to refute all of your arguments - I've got engines to build & heads to port (both 4V & 2V).
So I'll just say that your experience is limited to smaller capacity engines & what works with them, I play with a wide range of engine types on a daily basis - I know for a fact that a well designed 2V head used on a large bore production type engine is the equal of a similar engine equipt with 4V heads.
We are not talking exotics here, there is no point comparing a 5.7L 2V pushrod engine that does it's best work under 6000rpm to a megabuck 4V quad cam V8 that revs to 9000rpm - the average performance enthusiast could not afford such an engine, even if it was readily available.
The internal forces acting on such a large capacity engine revving that high make it necessary to use expensive forged internals & even then life span is limited - you just cannot rev a big engine that hard on a regular basis & have it live a long time.
The joy of a large capacity 2V engine is the stump pulling torque & throttle response - fitting 4V heads & making it rev to the moon would make them peaky, gutless at low rpm oversize copies of a DOHC 4-banger - everything us bogans hate.

+1

[Billzilla]

You haven't answered my question of whether or not you calculate the correct average diameter for the ports.
I'm also still waiting for those flow figures you said you had that showed the 4V head continuing to increase flow with big lifts.

And you've indirectly answered one thing I've been wondering about ->

The joy of a large capacity 2V engine is the stump pulling torque & throttle response - fitting 4V heads & making it rev to the moon would make them peaky, gutless at low rpm oversize copies of a DOHC 4-banger - everything us bogans hate.

If that's what you think and/or have acheived, then you're not doing it right sorry mate. It's a proven solid reliable fact that a good 4V engine will make MORE low-down torque than an equivelant 2V will, and just because it's got a 4V head doesn't automatically mean it'll rev very high, nor be required to, to make good power.

What I would strongly suggest you do, to learn how to build these things properly, is to build a restricted engine like my Suzuki. You'll learn a lot.

[Billzilla]

BTW - the intake ports of the WRX heads are barely larger than stock - the only metal removal is for the purpose of smoothing/blending, velocity is near identical to stock. The flow comes from near perfect bowl/short turn/seat/chamber design - my own design.
Grab your die grinder & see if you can beat it.

Ah good.
So what average flow for those have you calcualted?