EVO 8 head vs 1G head

colonelfox · Dec 6, 2003

I would love to see a 600 WHP stock long block EVO. 500 WHP can technically put one into the 10's with a great driver. If I go through with my plans it would be nice to own a car that does not require extensive bottom end strengthening.

16g-95GSX · Dec 8, 2003

If the block can handle 600awhp, it would honestly be comparible almost to the 2jz in terms of limits when, considering how much power you'd be making at the crank and the fact that its 4 cyl's pushing the power instead of 6, so 2/3. Honestly 530awhp to me is incredible considering the drivetrain loss has to be something like 22% or more. As assuming a 22% drivetrain loss that means its pushing around 679 crank hp. 600awhp would put it at 769 crank hp assuming the same loss.

eyebrowski · Dec 8, 2003

i am very impressed so far...i want to know when it is going to pop! AMS i think it can take a little more

tripleblackspdr · Dec 9, 2003

I just got done reading that guys web page... I hate to say it because I would love for someone to find something revolutionary but I don't buy it. its just that his web page seems way too much like agressive marketing material rather then a scientific experiment. If it was truly a scientific endeavor he wouldn't have come to his conclusions before his testing. That and there are always multiple combinations that can and cannot work in the end. I didn't see much effort in his write ups for the testing to eliminate extraneous factors. It was all pretty much anecdotal evidence..

tripleblackspdr · Dec 9, 2003

There have been others with small port theory. It is and always has been an open debate. As of right now I've seen lots of evidence for both sides and both seem to be working. This guy hasn't really presented what I consider to be definitive evidence either so IMO I would stick with what the machinists know best

TEC · Dec 9, 2003

I liked the articles he wrote and a lot of it agrees with some of the things I heard from some well know head porters about the velocity of the air being the key factor.

However, to use these articles as a basis to say that smaller ports are better for any engine would not be logical. Every engine has its own perfect port size. Also, notice that he failed to mention how effective this method would be in a forced induction engine.

Lastly on a totally different note, AMS is setting a new benchmark with what they are doing. However, I do believe the same results are obtainable on the DSM equipped 4g63 early model engines. What we have to remember is that the technology and ideas that set the benchmark years ago on these engines at 500hp is now pretty ancient. I believe that with a proper standalone unit both engines would put on a good battle.

lancerman · Dec 10, 2003

Lastly on a totally different note, AMS is setting a new benchmark with what they are doing. However, I do believe the same results are obtainable on the DSM equipped 4g63 early model engines. What we have to remember is that the technology and ideas that set the benchmark years ago on these engines at 500hp is now pretty ancient. I believe that with a proper standalone unit both engines would put on a good battle.

Please! The 525whp was acheived with stock small port head, stock intake manifold, and breathing through an un modded karmann meter. No you will not get this kind of power out of a stock 1g head , stock 1G intake, breathing through an unmodded karmann meter. NOT EVEN CLOSE

The best results we are aware of is jeff hill who used stock 2g pistons on 1g rods, built head, SM intake, haltech. 518 WHP.

Nobody has tried to push the stock 2G stuff past 450whp. The rods cant handle it. The EVO rods look identitclal in size but are stronger forged units.

Pretty strong evidence 2g ports are superior. But go on believing what you want. But at least have a good example to back up your claims.

natedogg66 · Dec 10, 2003

How's this? What do you think would happen if one were to port an EVO head to the size of a 1G head and left everything else more or less the same? That means that we are looking at larger ports on both sides. If the car gains hp then, it would show (on Evo 4G63's anyway) that larger ports are better. If it loses hp it would show the stock small port Evo head design is superior. If it stays the same I would tend to thing the large port design is superior because we'd be seeing extra turbulence for not matching with the manifolds but the larger ports are making up for it therefore keeping the hp pretty much the same. What do you guys think? I own both a 1G DSM and an Evo so I'd be interested in these results. (No, I will not try this on my Evo, its my comfortable daily driver

)

Now this would NOT conclude that the 1G head design is actually superior if the larger ports were to win because I'm sure there are other changes within the Evo head make it superior overall. Port size aside, IMO, the notion that the Mitsu engineers did not make other improvements to the 4G63 (their top of the line, racing engine) head over a 15 year span is laughable. This experiment would simply prove whether larger ports or smaller ports are better on an Evo 4G63 head. If no results are found to point one way or another it could be taken a step further. One could port match the manifolds to the head and see what the results are after this.

Now we just need to find a donor Evo...

TEC · Dec 10, 2003

lancerman said:
Please! The 525whp was acheived with stock small port head, stock intake manifold, and breathing through an un modded karmann meter. No you will not get this kind of power out of a stock 1g head , stock 1G intake, breathing through an unmodded karmann meter. NOT EVEN CLOSE

The best results we are aware of is jeff hill who used stock 2g pistons on 1g rods, built head, SM intake, haltech. 518 WHP.

Nobody has tried to push the stock 2G stuff past 450whp. The rods cant handle it. The EVO rods look identitclal in size but are stronger forged units.

Pretty strong evidence 2g ports are superior. But go on believing what you want. But at least have a good example to back up your claims.

You have problems with your statements:

One, is that as you stated the best results that you are aware of was by Jeff Hill. We aren't aware of everything that is going on with all owners. It is possible that someone could have surpassed his mark without us knowing it. There were many things happening so fast during 95-98 that many people were not aware of as the areas of information proliferation was very small.

Second, no one is going to go out and test the limits of a 2g at this point and time. There are too many factors against it and its not really worth the effort. However, I do remember reading awhile back of someone turning 5XX on a VR4 with stock 1g head, stock 1g block, with stock 1g intake a month ago or so.

I have, though, seen dyno results of a 2g head placed on a 1g block. The results were a minimal midrange gain with a top end loss.

Third, with the exception of the ports the 2g head is a better design due to its not having a 90 degree bend down from the port to the valve and a few other things. This is why Rau, and even I, used the 2g head for racing, but only after it was EXTREMELY modified. The 1g head with some port work, some filling in the right areas and otherwise is vastly superior. Why most racers choose to go with the 2g head is because they would rather remove material to make it flow than than add material and modify.

On the subject of proof, I think you should compare apples to apples. Comparing an EVO VIII engine to a 2g engine is like comparing a V8 Cleveland 351 to a Windsor 351 they may both be 351's but they aren't nearly the same. Your example of this guys theory on small ports is taken totally out of context. AGAIN, He is referring to NON forced induction applications.

Please show us some proof with the same motor and a 1g head then switching to dyno with a 2g head, then you can claim one is better than the other.

WombatTSi · Dec 10, 2003

lancerman said:
Please! The 525whp was acheived with stock small port head, stock intake manifold, and breathing through an un modded karmann meter. No you will not get this kind of power out of a stock 1g head , stock 1G intake, breathing through an unmodded karmann meter. NOT EVEN CLOSE

1) again comparing apples to not so similar apples. sure it was done on all stock EVO components, but all those components (intake, MAS, Intake manifold, TB etc etc) are all VASTLY superior to the 1g equivelant. no one is arguing that. nor is anyone arguing that the EVO head is inferior to the 1g head. its not. its MUCH MUCH better. 14 years better at least. the argument is wether the EVO head would benifit from larger intake ports, and I, as well as several others in this thread, think the answer is yes.

However, that being said, untill someone Actually does back to back dyno pulls, we're all just bench racers.

2) that stock 1g block HP number is OLD; REALLY old. As in back in the day when the 20g was a RACE ONLY turbo, and when anything bigger than 550's was insane. If someone tried today Im confidant that a "like new" condition 1g block/head could eaily eclipse the 550 whp mark. But, this thread is about heads, not bottom ends.

-Keyboard Racer Ryan

natedogg66 · Dec 11, 2003

WombatTSi said:
1) again comparing apples to not so similar apples. sure it was done on all stock EVO components, but all those components (intake, MAS, Intake manifold, TB etc etc) are all VASTLY superior to the 1g equivelant. no one is arguing that. nor is anyone arguing that the EVO head is inferior to the 1g head. its not. its MUCH MUCH better. 14 years better at least. the argument is wether the EVO head would benifit from larger intake ports, and I, as well as several others in this thread, think the answer is yes.

However, that being said, untill someone Actually does back to back dyno pulls, we're all just bench racers.

This is exactly what I was trying to get across. I'm sure Buschur, AMS, or Pruven will get to the point soon enough when they want to start experimenting with the Evo head. It may take a few months, but it will definitely answer the good questions that have been brought up in this thread.

Wreckleford · Dec 12, 2003

My question is how do the Evo ports compare in size and shape to the 2g ports?

lancerman · Dec 13, 2003

My question is how do the Evo ports compare in size and shape to the 2g ports?

The evo ports are the same size as 2g. But will will not see any evidence coming evo guys. For that to happen someone would have to match port a 1g intake manifold to an evo port without touching the bowl area or seats or exhaust sides. And there would have to be a 1g intake that would bolt up wich also doesn't exist. It is very easy to pick up 30hp from exhaust porting and loosing 10hp from opening up the intake side.

There are threads where 2g guys replaced their stock 2g head with stock 1g head and intake and didn't go a smidge faster at the track. And keep in mind going from 54mm TB to a 60mm TB is a pretty big change in itself that would mask the true results.

At the shootout 2002 there were two 9 second cars that damaged their ported heads and had to bolt on bone stock 1g heads. Neither car suffered performance. One of them went on to set a new best at like 147mph. Faster than he was going on his ported head. Clearly indicating bigger ports are not better.

There is a tuner mag on the shelf right now, sorry I didn't catch the name of the mag. There is a honda build in their that shows a close-up of both intake and exhaust ports. No attempt to make them any larger. Smaller than 2g both intake and exhaust. No problem making 650 horsepower.

It going to be real hard to get proof on this one simply cause no one is going to do a true back to back" no other changes" to prove it. Actually I am in a postion to prove it more than anybody. My evo 1 has the small ports, evo stlye runners, 60mm TB, and the engine on the same side as 1g cars. So bolting on a 1g head and intake would give us the answer.

Wreckleford · Dec 14, 2003

I'm in the same position - rebuilding my Evo I engine but have a spare big port head/manifold. I'm trying to decide which head to put on. I may put the big port head on and if I don't like it I will switch back

BTW, when I asked about comparison of the Evo ports to the 2g ports, I meant the later evos, such as the 8 (seeing as the head is different to the Evo I head).

11sec4cyl · Dec 14, 2003

lancerman said:
And keep in mind going from 54mm TB to a 60mm TB is a pretty big change in itself that would mask the true results.

*cough* 52 *cough*

Will's Fiero · Dec 15, 2003

F/I vs N/A

TEC said:
AGAIN, He is referring to NON forced induction applications.

what's the difference between a naturally aspirated and a force inducted engine?

N/A engines have equal back pressure and manifold pressure at WOT, while FI engines have more back pressure than manifold pressure. This changes cam requirements to deal with possible reversion.

N/A engines have 14.7 psi across the intake port & valve at WOT, while F/I engines have 14.7+boost across the intake port.

Why on earth do people think that port dynamics are completely different with 30 psi across the port vice 14.7? NOTHING in flow equations favors atmospheric pressure for ANYTHING. It's all just varying degrees of the SAME thing.

TEC · Dec 15, 2003

Re: F/I vs N/A

Will's Fiero said:
what's the difference between a naturally aspirated and a force inducted engine?

N/A engines have equal back pressure and manifold pressure at WOT, while FI engines have more back pressure than manifold pressure. This changes cam requirements to deal with possible reversion.

N/A engines have 14.7 psi across the intake port & valve at WOT, while F/I engines have 14.7+boost across the intake port.

Why on earth do people think that port dynamics are completely different with 30 psi across the port vice 14.7? NOTHING in flow equations favors atmospheric pressure for ANYTHING. It's all just varying degrees of the SAME thing.

In one application (NA) air is being pulled into the head by the engine, in a forced induction application the air is being forced into the engine by the turbocharger, this is the major difference.

Port shape, runner shape, runner length, become more important in a NA engine because of this. NA engines need to have a balance between velocity and amount of air flow, due to short timing events (the piston moving in a downward motion) in which the air is actually allowed to enter the combustion chamber. The most common mistake in porting a NA head is to open the ports and runners too much which hurts the velocity of the air entering the port which means less air will actually have the chance to make in thereby hurting performance. The author of this particular article is making the point that velocity is more important than size, which I am inclined to agree with.

However, in a forced induction engine, velocity becomes less important because the air is being compacted into the runners and pressed against the back side of the valve by force of the turbocharger. While engine timing events are still important, the constant pressure induced by the turbocharger greatly downsizes the loss of velocity that would be typical on a NA head due to larger ports and runners.

To ignore this would be to throw out years of research and belief concerning head porting for application. This is why most places port differently depending on the intended use of the head...one style of porting for a nitrous head, another method for a turbo head, another for a NA head.

lancerman · Dec 15, 2003

However, in a forced induction engine, velocity becomes less important because the air is being compacted into the runners and pressed against the back side of the valve by force of the turbocharger.

Velocity does not become less important. You are theorising wrong. You are forcing air into the intake manifold, yes. But it is not forced into the engine. The piston travels way faster than the air it is trying to suck in. It is still trying to suck in on a turbo car. The turbo car simply has a denser mixture to suck in.

Three years ago me and a buddy built our first 2.3 motors. Our setups were nearly identical except he ran a stage 4 ported head. I ran a cleaned up head. His car made 380whp/350tq. My car made 400whp/400tq on 2 psi less boost. We both knew where the mistake was. He was pissed he spent 1500 on that headwork.

lancerman · Dec 15, 2003

This discussion is bench racing at its finest. I think we are all aware of this. There currently is no back to back tests that would prove what is better. There have been remarkable achievements using both heads. Hell Andre just made 503whp on 93 octane using a bone stock 1g head. But would he make 520 with bone stock 2g head and evo intake? The world may never know....

Will's Fiero · Dec 15, 2003

Re: Re: F/I vs N/A

TEC said:
In one application (NA) air is being pulled into the head by the engine, in a forced induction application the air is being forced into the engine by the turbocharger, this is the major difference.

NO! There's VERY LITTLE DIFFERENCE. There's no such thing as suction, either.

In a naturally aspirated engine, air is being pushed in by atmospheric pressure. In a forced induction engine, air is being pushed in by atmospheric pressure plus boost. This is soo simple, yet no one understands it.

Differing port schemes for turbo, s/c, n/a or N2O result from the fact that these different modes of operation require different relationships between intake and exhaust flow.

However, saying that velocity matters for an N/A engine, but not for a turbo engine is just ridiculous.

EVO 8 head vs 1G head

colonelfox

16g-95GSX

eyebrowski

tripleblackspdr

tripleblackspdr

TEC

lancerman

natedogg66

TEC

WombatTSi

natedogg66

Wreckleford

lancerman

Wreckleford

11sec4cyl

Will's Fiero

TEC

lancerman

lancerman

Will's Fiero

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