just wanting to use a 2g cylinder head...

[ctm]

Searched and searched and also PM'd some veterans but definitive answers are elusive. I am considering a swap to a 2G cylinder head. Here is the most easily obtainable answer that has been consistent: a 2g head from a 7 bolt motor does work on a 6 bolt if one bores/drills out the head stud hole to fit the 6 bolt head stud (7 bolt motor has 11mm head bolt, 6 bolt motor has 12mm head bolt)... THANKS grocery_getter!!!

I am seeking confirmations on some things that (depending on who you ask), the answers can differ significantly:

Issues and considerations must one take into account when considering using a 2g head for a 1g or GVR4 6 bolt motor...

1) it was suggested the the use of a 2G head means you need to also use a 2G intake manifold. despite the smaller intake opening on the 2G cyl. head, can't one just use the GVR4 intake mani (and will this bolt on without problems)?

the ability to simply use the GVR4 intake mani also avoids the problem on faces when they reuse the grv4 throttle body, which is bigger than the 2g throttle body. Otherwise, to make this work if one had to use the 2G intake manifold, you would have to port the intake to match the gvr4 throttle body.

2) it was also suggested that one needs to also use a 2G thermostat housing... again why can't one use the one for the GVR4?

If this is true, then do you have to also swap all the sensors on the gvr4 thermostat housing onto the 2G thermostat housing. Is this an absolute or is there a workaround (with minimal compromise)?

3) also, a 2G main water pipe needs to be used... why doesn't the GVR4 unit, mods to it or other workaround options, work?

It would also be great to receive a very good reason explaining what the advantages are in later 2G heads having the updated larger lifters on top.

TIA - ctm (newbie 'coz I had to re-register)

 

What is your primary reason for wanting to use the 2G head?

I've read that the smaller ports in a 2G head will improve low end torque but at the cost of mid and high end flow. Like having a Cyclone intake that is welded shut. Other than that I've never heard any reason for using a 2G head on a 1G motor. Most people go the other way, they install a 1G head, intake and throttle body on their 2G motor to improve flow. You mentioned the improved lifters, but if that's what you're looking for just buy a set of revised 3G lifters and drop them into your 1G head.

Using the stock Galant intake on a 2G head is going to really hurt your airflow because you'll have a large step where the big intake port meets the small head port. Completely defeats the extra flow provided by the larger 1G throttle body.

 

[steve]

I remember hearing, stock for stock the 1G ports are larger, but the 2G can be ported out larger than the 1G. /ubbthreads/images/graemlins/dunno.gif

 

[jepherz]

I think this is definitely a case where "porting" all you can get out of the head, isn't the reason for going to a 2g head. The ports in a 2g head are much less tall, but this creates a less-abrupt passage into the cylinder. You can think the 2g head advantage much like imagining a semi tractor-trailer taking a wide corner, in order to increase the radius of the corner. A 1g would be much more like the same truck taking a corner very sharp, and slamming into the curb.

I don't have any factual data to back any of this up, but this seems like a case to me where bigger is NOT always better.

As mentioned above, using a 1g intake on a 2g head would prove to be VERY restrictive and a bad idea.

 

I remember hearing that too, but it doesn't seem like anybody is actually doing it. Still see everyone porting 1G heads. I can't imagine the gain in a ported 2G would really be worth the extra effort, but I could be wrong. Are the water passages in different locations or smaller in a 2G and thats what allows them to be ported more?

 

[Wizardawd]

(1)The smaller ports aren't really the lack of power that a 2g has. T-Too Tiny turbo, absolutely poorly designed intake manifold and too conservative cams. The 2g's sharper entry angle into the head is better for performance and the 1g's ports are just a bit too large for good low end velocity.
On the other hand, the 1g intake manifold is one of the best if not THE best intakes for a street car. So...I would use the 2g head, have a GOOD machine show open up the intake ports to match, then do a good blend job all the way to the bowls. And use the 1g intake and TB.
(2)You can use the 1g thermostat housing.
(3)In May 1992 (IE 7-bolt) they also revised the coolant passages for better flow and heat absorption.
(4)2g head has much more meat to port with. Meaning you get a better chance at getting the correct angles and smoothness of curves that you need for good flow.

But for most of the cars out there....a good 1g is just fine.

Wiz

 

[slugsgomoo]

if you are at the point where a 2g head is limiting your power production, you have one of the top 10 fastest galant vr4's in the world. If not, bitching about how much it may or may not choke flow on a stock port is

Here's why you can't use the thermostat housing or waterpipe from a six bolt. namely, the 2g head is totally different and they are not compatible.

for what it's worth i'd be careful with port matching to a 1g manifold, since most places that do it cut the floors and you lose the velocity that is what makes the 2g head so awesome. I'd talk to Boostinhard on here about it before i had anyone cut up a nice 2g head. /ubbthreads/images/graemlins/dunno.gif

You can always order a SMIM for a 2g head if you're really worried about the flow-choke in the upper revs. Most of the choke from the stock manifold comes from the tiny plenum on the stock 2g manifold. (tiny turbo & whatnot notwithstanding).

and for all of you worried about it choking the high end on your stock 2L motors, that's a 9:1 2.4L /ubbthreads/images/graemlins/rofl.gif

 

[Dialcaliper]

I might point out that if you open up the intake ports to match the 1G intake and bolt pattern, you've just destroyed the "sharper entry angle" that the 2G head has (which was gained mostly by closing up the bottom of the port to make it shorter). Essentially what you'd be doing is paying someone a ton of money to nearly replicate a 1G port in a 2G head.

The 2G works well for porting because the lower portion isn't cut out already, and you can just port upwards, and maintain the port angle. It's true that the coolant passages were moved away from the intake ports, so there's more material to cut out, but you really need to be making a serious race engine to need that severe of porting, and for it to make any difference.

Stock for stock, the 2G head is better for it's low end torque, but if you want that, you might as well just bolt on a cyclone manifold for a fraction of the price of a porting job.

The 1G head is a very well designed head, but the factory redesigned for the 2G head for a couple of reasons:

1) The same head design is used on the NA engines, of which they sell far more than turbocharged versions, They wanted better torque without resorting to building expensive dual runner intakes like they did on the JDM versions. The open port design of the previous head was not required to achieve the "stock" power levels that they wanted, so they went with a head that flows better at lower RPMs instead of higher, so that the NA versions would have more midrange.

2) They wanted to increase power, yet retain or improve gas mileage and emissions due to stricter regulations, so they had to come up with tweaks to improve efficiency. Manufacturers don't revise designs simply to produce more power only. It's the same reason the 4B11 engine has smaller exhaust valves than the 4G63, which is not motivated by increased power.

We kind of forget sometimes that we're dealing with normally aspirated engines that have been designed as a compromise to stand up to turbocharging. The 4G engine was incredibly overbuilt and overdesigned originally, and then tweaked and modified to meet rising regulations and different requirements over the years.

 

I use a ported 2G head on my 6 bolt motor in the '95 Talon. Just because of all the 2G head haters at the time. "You'll never make >500AWHP" some said. 600AWHP bitches! /ubbthreads/images/graemlins/cool.gif

 

[ctm]

thanks for all the comments and info thus far...

dsm_drew - the reasons for going to a 2g cylinder head are as you alluded, the smaller inlet ports and the "sharper entry angle" design into the head (as detailed by jepherz, Wizardawd, slugsgomoo and Dialcaliper). the consequent increase in low end torque/velocity and overall performance/response are goals.

since the stock GVR4 intake mani bolts up to the 2G head and with no port matching I will use it (this was the desired plan and I agree with Wizardawd that these 1g/GVR4 units are superior to those for the 2g). QUESTIONS: any specific details on the need for additional porting of the deeper passages into the cylinders? slugsgomoo and Dialcaliper any specifics on this would be appreciated.

using the stock intake mani makes easy the decision to use the stock TB, coil pack, etc., so will do that. QUESTIONS: any other issues to consider as far as the use of a stock TB/intake mani to the 2g head? will it matter what gasket (stock vs. 2g) to use between the mani and the head?

as to using the 2g T-stat housing, comments from slugsgomoo and grocery_getter (offline) imply that I'll have to. QUESTIONS: i recall the 2g unit has coolant/radiator cap on it... will this part be discarded when one swaps all the sensors from the gvr4 T-stat housing?

will use the 2G main water pipe. QUESTIONS: will using a TD06 style turbo (street strip 20G) or FP green/red require any mods to this pipe? any necessary mods to the main 2G pipe when using other turbos like an FP 3052 or other GT style turbos?

TIA.

 

[jepherz]

As far as the gasket to use, you'll want to go with the 1g intake manifold gasket. Since the ports are larger, and you'll be porting to match and the bolt pattern is the same, you'd run into problems using the 2g gasket (ports are too small on it).

I'm guessing the sensors on a 2g t-stat housing are the same on a 1g, but you'd want to confirm. I don't think sensors will be a problem, but it'll be up to you to decide if you want to have two radiator caps or not (one on the radiator, one on the T-stat.)

 

[1badgvr4]

Im looking to buy this head by bj's cyl heads.How do the intake ports look?

 

[grocery_getter]

You will have an intake leak if you use a 1G manifold with a 2G head and vice versa.

The 1G intake port is so tall that the bottom corner part of the port opening on a 1G intake is outside that of the 2G head flange casting. Which is why I told you what I told you in the PM.

 

There sits a 2G head on a 6-bolt block. Had to drill the head bolt holes to clear the 6-bolt studs (5 clear and 5 don't, I drilled them all). I used the 1G thermostat housing because I have a 1G Fluidyne radiator, otherwise the GVR4 unit would have been used (at least the top hat). The 6-bolt water pipe was used as well. I ported the intake manifold (2G) to match the 1G throttle body. Used 2G manifold-head gasket. Done.

 

[ctm]

jepherz - thanks for your comments.

jesse - nice set-up and the info you provided is appreciated.

andre - many thanks for your initial help and for taking the time to provide input on this thread. based on your PM and follow-up info it appears that the solutions that jesse detailed are reasonable and seemingly workable compromises, yes or are there yet-unmentioned considerations?

as always TIA.

 

[Bimmubishi]

I am going back to a "2g/Evo" cylinder head this winter. I'll be using an Evo intake mani and TB (or a BK which I have now)

My reasons are similar. I'd like to try to see what the difference is in HP and TQ. I have a feeling that the 2g will make more of both based on a few things.

I'll post results when I finish.

 

[grocery_getter]

CTM, no problem.

Jess, that upper radiator hose has an air trap?

Andre

 

^ Probably, we'll see. Still need to make hard pipes and weld the radiator cap to the radiator.

 

[3rdstrikedsm]

evo 1-3 head with intake manifold is a good set up and very close to 2g but e3 intake manifold way out flows any 1 or 2g.

 

[ctm]

3rdstrikedsm,

interesting option you propose. do you have specific data that support your claim about e3 mani's flow capability relative to 1g or 2g units? if not, perhaps you can provide links that have this info.

also, are there more than one type of e3 intake mani? please also details any issues with using this on a 6 bolt motor (not yet mentioned in this thread, which mostly goes over using a 2g head)?

do you have one of these you want to part with (if so what type of e3 intake mani)?

TIA