1G cylinder head question

[TurboBird]

What is the most I should pay for a used 1G cylinder head?? Or should I try to find one that is rebuilt? I mean either way I intend to put a head that is rebuilt/cleaned (possibly ported) into my car; I just want on that is in good condition in my car. Thanx

 

[gixrman]

First of all why do you want to go to a 1g head? the 2g head will flow just as good a a 1g. You will loose low-mid range with the 1g(but gain some topend, if thats what you want).You can find heads on ebay for cheap or mitsubishigraveyard.com .
jacksonmachine.com, and sloyboy racing have good info on built heads not to mention several others.
Unless your running bigger than a 50trim the 1g head conversion is'nt worth it.

 

[TurboBird]

I was told that it was an upgrade that would be needed for me to get the most, or anything out of an upgrade to a 1G Tb and intake manifold.

 

[gsx951]

If you're going to the effort of a 1G head swap, why not just do the whole 6 bolt conversion?
I'd leave things alone like the other poster said unless you're out to drag.

 

[leakyfaucet]

the 2g head will flow just as good a a 1g.

Wrong.

 

[gsx951]

Wrong.

It may seen counter-intuitive but sometimes smaller ports flow better....

http://mototuneusa.com/thanx.htm

check out the info on porting. this isn't theory, it's track and dyno proven.

 

[leakyfaucet]

It may seen counter-intuitive but sometimes smaller ports flow better....

Sometimes, like in low rpm situations, but not in this one.

 

[gsx951]

You need to read the info first. Like i said...it's counter-intuitive.
(I don't think Super Bike race motors ever run at LOW rpms!)

 

[leakyfaucet]

Show me a 1G that benefitted from swapping to a stock 2G head/manifold.

A N/A motorcycle engine must be set up quite different from a forced induction car engine.

 

[gsx951]

Show me a 1G that benefitted from swapping to a stock 2G manifold.

A N/A motorcycle engine must be set up quite different from a forced induction car engine.

the discussion was regarding heads and their ports, not manifolds. at the rpm's you'll see on the street, 1G ports are way big. mitsu reduced them to improve velocity.

 

[TurboBird]

So would a 1G TB and intake manifold upgrade have any affect and be worth it w/o the head or should I just spend the money else where?

 

[leakyfaucet]

It may seen counter-intuitive but sometimes smaller ports flow better

He doesn't suggest that smaller ports flow better, he's suggesting they allow for more velocity.

the discussion was regarding heads and their ports, not manifolds.

I realized that I typed manifold when I meant to type head, and I corrected it with head/manifold, but you must have already been typing this when I changed it. Sorry.

at the rpm's you'll see on the street, 1G ports are way big. mitsu reduced them to improve velocity.

Not true. Mitsubishi changed them to better match the turbo. The turbo runs out of steam earlier, so they wanted smaller valves to match. There's no point in having a valvetrain designed to make power from 5-8000 RPM if the turbo craps out at 5500.

What you're not considering is that these motorcycles tested were N/A. With Forced induction, every explanation of why those engines made more power is void. With a constant pressure forcing air in, bigger is better (to a certain extent, and assuming all intake components match each other).

 

[gsx951]

So would a 1G TB and intake manifold upgrade have any affect and be worth it w/o the head or should I just spend the money else where?

pull your pan and measure thrust clearance. i personally would not sink money into a 7 bolt motor. what you do is determined by your goals for the car (and what condition the bottom end is in.)

 

[gsx951]

He doesn't suggest that smaller ports flow better, he's suggesting they allow for more velocity.
I realized that I typed manifold when I meant to type head, and I corrected it with head/manifold, but you must have already been typing this when I changed it. Sorry.


Not true. Mitsubishi changed them to better match the turbo. The turbo runs out of steam earlier, so they wanted smaller valves to match. There's no point in having a valvetrain designed to make power from 5-8000 RPM if the turbo craps out at 5500.

What you're not considering is that these motorcycles tested were N/A. With Forced induction, every explanation of why those engines made more power is void. With a constant pressure forcing air in, bigger is better (to a certain extent, and assuming all intake components match each other).

the 2G head has smaller valves?

if you were correct, and bigger is better, then explain the rationale for "D" porting.

 

[leakyfaucet]

if you were correct, and bigger is better, then explain the rationale for "D" porting.

D porting isn't used as much for all out, high RPM power. It's used more for low and midrange power and serves a very similar purpose of a swirl design- to allow better fuel atomization.

 

[scottsee]

wow, this thread sure went off topic fairly quickly. everything that i have learned in the year that i've owned my eclipse is that the 1g tb, intake manifold, and cyilder head provide extra air volume to enter the combustion chamber , helping performance over the smaller 2g tb/intake/head. all becasue of the tubo's used. tdo5h need more exhasut to spool up then the t25. but to answer your question, the most i would pay is $30 for a used head. the local parts yard here sells them for $26 w/ cams, springs, valves exc. thats me personaly. any 1g 2.0l cylinder head will fit on the 2g shortblock, some will require you to relocate the cam-angle sensor. and if you buy a 1g head isnt from a turbo, i'd recomend rebuliding it with diffrent cams. besided that. im almost possitive the full 1g head/tb/intake swap on 7 bolt block provides a 40hp over stock. cheers

 

[TurboBird]

But now what about the swap, TG and intake Mani. w/o the head?

 

[gixrman]

if you to just swap the TB, intake it will not help. You would have to take the 2g head off and port match the the 1g intake. Think of 1g intake ports as <O> and 2g ports as <o>. Things don't match up. Theres no point in swaping all of this if your motor is still stock. The t-25 can't support the 2g motor as it is why throw on a head with bigger ports?
Unless you upgrade the turbo theres no point.

Now the TB swap does work even on a stock motor for better throttle responce. Do some searching this has been covered many times.

 

[gixrman]

im almost possitive the full 1g head/tb/intake swap on 7 bolt block provides a 40hp over stock. cheers

Yes if you have supporting mods, remember his motor is stock.

 

[pinknuggit]

yeah, all of the port velocity with smaller size runners is void when you throw a turbo into the mix. If I was gonna build an N/A 4g63, I would put on a 2G head and smooth out the edges in the intake runners.

 

[TurboGeoff]

1G heads are better for a turbo application, period, end of story.

 

[gsx951]

1G heads are better for a turbo application, period, end of story.

Tell that to the guys on the Auto-X list.... www.farnorthracing.com

Dennis is doing 348 awhp and 378 lb/ft of TORQUE with a bone stock 2G head that was never off of the car and a Big28 turbo. (a nice curve with tons of area under the peaks.)
Don't you think Dennis and Marco would have fitted a 1G head if they thought it would help?
Sometimes it is good to take a look at things you believe are wrong and examine your premises.

 

[defrag010]

just cause someone has good results with something doesnt mean its better.

 

[leakyfaucet]

Tell that to the guys on the Auto-X list.... www.farnorthracing.com

Dennis is doing 348 awhp and 378 lb/ft of TORQUE with a bone stock 2G head that was never off of the car and a Big28 turbo. (a nice curve with tons of area under the peaks.)
Don't you think Dennis and Marco would have fitted a 1G head if they thought it would help?
Sometimes it is good to take a look at things you believe are wrong and examine your premises.

What a terrible argument. They could have used a 2.4L engine too. But I guess those aren't beneficial at all. Because if they were, wouldn't the guys at farnorthracing.com be using them?

 

[AWD Eagle]

Do guys like Shepherd and Buschur run 1g or 2g heads? That should answer your questions about which head is better.