2g head on a 1g block

[DSMinn0vati0ns]

I don't think that is right Joe. I have a 2G CAS on mine and I'm running a 6 bolt with a 2G head. I chose it so I didn't have to switch around the sensors. I just reused them. I believe on the 2Gb version, it just bolts up. I verified and looked at my invoice and sure enough, 2G Crank Angle Sensor was used.

d

so your saying that i wont need the 1g cas? i can use all my sensors that i have now?

 

[TurboAnything]

Dsm-onster loves his 1g head a lot and will fight to the death. Personally i think the (2g evoI-III) head is better but its just my opinion. I also think there is no difference between 2g and evoI-III heads and that it was designed around the 16g turbos. I am willing to test the heads i can get cheap dyno time from a place called APG and i have a lot of 1g heads but i have no 2g heads or the stuff to make it work. I want to to do a back to back on the dyno 1g head with 1g manifold stock and a 2g head stock with a stock 2g manifold both with the 1g throttle body and 1g cams.

 

[dsm-onster]

Dsm-onster loves his 1g head a lot and will fight to the death. Personally i think the (2g evoI-III) head is better but its just my opinion. I also think there is no difference between 2g and evoI-III heads and that it was designed around the 16g turbos. I am willing to test the heads i can get cheap dyno time from a place called APG and i have a lot of 1g heads but i have no 2g heads or the stuff to make it work. I want to to do a back to back on the dyno 1g head with 1g manifold stock and a 2g head stock with a stock 2g manifold both with the 1g throttle body and 1g cams.

For Pete's sake, please do!!! I have no 2g heads. . .

 

[squeak104]

If people weren't so far away from me I'd gladly let someone borrow my spare 2G head to test with as long as I get it back in good shape. Any takers?

 

[DSMunknown]

Good lord, dont listen to that man. Ive been running an evo 3 intake manifold with 1g throttle body on my 98 Eclipse GSX for a long time now, and there are many others that have too. No modifications necessary, I dont get where he is getting this bullshit.

Yeah, I don't know what the eff he's talking about either.

 

[Siral3x]

What is it wrong with the thinking that Mitsu would design a head for more lowend torque then throw on a small quick spooling turbo and give the cams more overlap ??? I agree that the evo3 has similar port design, but more money is made in the american market than the japanese market. We'll never know all of how/why Mitsu made it's decisions.

Stating a 2g head does nothing to end the debate. There are 600whp 1g heads running around, too. 1g heads do the same as 2g heads. I've seen them ALL perform similarly with similar setups. No one has ever verified that a 2g head flows better than a 1g head. So the arguement that velocity is better than flow goes into a circle unless it's been proven. The best thing about the 1g head is the ability to use the better 1g intake manifold. No one has proven than the smaller ports cause the 2g head to outperform a 1g head due to higher velocity.

There is no proof of anything. . . Where are we going with this thread ?

I highly doubt Mitsu is making more money in the American market, since they have been discontinuing cars for quite a while AND they were talking not to long ago to LEAVE the North American market period. IE: The colt it's not made for years in US; Europe and Japan is enjoying AGAIN a Ralliart turbo COLT making 190hp out of a 1.5L, or the stock CZT making 150hp. etc...

Again if you think that Mitsu designed cyl heads around turbos then you are soo wrong. The 2g head wasn't designed only to be paired with a t25. The evo 1,2,3 head is the same as a 2g except cams, and it's paired to a bigger turbo then the 1g head! That's why they named it an EVO, it's all about evolution; evolving from side mount intercoolers to fmics, from 1g heads to 2g..from t25 and 14b to steroid pumped 16Gs, to 20Gs, from the GVR-4 aka EVO 0 to the last EVO III!Well yeah you say that in US the early evo's and parts were not available and Mitsu is doing this and that, but that doesn't stop you to limit your thinking just at the U.S border..does it???
2G head is an improvement over the 1G, otherwise why would't Mitsu use a 1G in their EVOLUTION??Well, they didn't!

 

[dsm-onster]

I highly doubt Mitsu is making more money in the American market, since they have been discontinuing cars for quite a while AND they were talking not to long ago to LEAVE the North American market period. IE: The colt it's not made for years in US; Europe and Japan is enjoying AGAIN a Ralliart turbo COLT making 190hp out of a 1.5L, or the stock CZT making 150hp. etc...

Again if you think that Mitsu designed cyl heads around turbos then you are soo wrong. The 2g head wasn't designed only to be paired with a t25. The evo 1,2,3 head is the same as a 2g except cams, and it's paired to a bigger turbo then the 1g head! That's why they named it an EVO, it's all about evolution; evolving from side mount intercoolers to fmics, from 1g heads to 2g..from t25 and 14b to steroid pumped 16Gs, to 20Gs, from the GVR-4 aka EVO 0 to the last EVO III!Well yeah you say that in US the early evo's and parts were not available and Mitsu is doing this and that, but that doesn't stop you to limit your thinking just at the U.S border..does it???
2G head is an improvement over the 1G, otherwise why would't Mitsu use a 1G in their EVOLUTION??Well, they didn't!

We're all throwing out valid opinions. Please talk to the above poster about borrowing his head. Otherwise, we all know there is no proof. And, we all know 1g heads have done 9 second passes and eclipsed the 600whp mark unported.

Best to 'run what you brung'. You all seam to want this to be revolutionary , but no one has noted a difference. Some one needs to start the re-evolution! Remember, I'm not exactly an advocate of a 1g head. But where's the information that merits my time and money to swap?

The original poster should use the 1g head because the 1g intake manifold is clearly better and he would have the better cams already installed in the head (less work). If he upgrades to a SMIM and aftermarket cams then he has solace in the fact that there really has been no proven hp difference.

There really is so much that needs to be done to both heads compared to, say even an h22 head, that we're agueing over crumbs from the table. If you want a better head, go get a 2g head and get a top-tier professional to have at it.

 

[TheBoosted96GST]

to everyone talking about the oversized headbolt holes needing to be done to a 2G head...... like 6years ago I did the 1G in a 2G swap in my '96 GST I wen't to town on the bottom end but ran outta money for the top so anyway I used my 2G (96) head (which I rebuilt and put new valves in) on my 1G 6-bolt block and it bolted right on without honing the head bolt holes bigger, no problems. So maybe 95-96 heads dont need the bigger bolt holes? But I eventually went with a 1G head a few months afterwards. I still have the 96 head, and its in perfect condition along with the intake manifold, I wanna see some answers I was thinkin of selling the 2G head since I now have a 1G but this thread's got me second thinkin'

 

[gijoe985]

Well, I might not be the original poster, but I am the one who revived this thread after being dead a year. All I have to say is that I am very happy with all the responses. I've learned a lot. Regardless of which is "right" there was a lot of useful theory and ideas. Hopefully this inspired someone to actually run the dyno with both. It'd be quite the awaited event. We might even have to sell tickets?

 

[DSMunknown]

The evo 1,2,3 head is the same as a 2g except cams

Hmmm, that's not what you said in this thread. I'll give a couple quotes.

-cyl head is 2G ALIKE, NOT exactly a 2G.. EVO heads have different port geometry

As you can see from the part number list the EVO III cyl. head has a diff part number then the 2g head

Has something changed your views/understanding since these previous posts?

We're all throwing out valid opinions. Please talk to the above poster about borrowing his head. Otherwise, we all know there is no proof. And, we all know 1g heads have done 9 second passes and eclipsed the 600whp mark unported.

Best to 'run what you brung'. You all seam to want this to be revolutionary , but no one has noted a difference. Some one needs to start the re-evolution! Remember, I'm not exactly an advocate of a 1g head. But where's the information that merits my time and money to swap?

There really is so much that needs to be done to both heads compared to, say even an h22 head, that we're agueing over crumbs from the table. If you want a better head, go get a 2g head and get a top-tier professional to have at it.

I have actually had a couple offers over the past week or so about obtaining an Evo II as well as an Evo III head. Exciting, isn't it?

 

[dsm-onster]

I have actually had a couple offers over the past week or so about obtaining an Evo II as well as an Evo III head. Exciting, isn't it?

Man, this would be excellent!!! Please keep working at this.

I'll trade someone my spare 1g head for a 2g head. If any wants it. . . . Of course, then I'd turn around and lend that head to Anthony .

 

[DSMunknown]

Man, this would be excellent!!! Please keep working at this.

I'll trade someone my spare 1g head for a 2g head. If any wants it. . . . Of course, then I'd turn around and lend that head to Anthony .

The only thing I have to work on is convincing them to not do or have any work done on the heads. Other than that, I'm not too worried.

 

[empie1]

Hmmm, Mitsubishi made the head bolt holes on the 1995-1996 heads one mm larger than neccesary for their stock head bolts?

the_jester had a 1995. We swapped in a 6-bolt and I personlly had to widen the headbolt holes.

Well, I dont know what to tell you...I have done the swap 2x...on 2 seperated 2ga dsms.Both times, I reused their head and didnt have any issues.I know of at least 3 other people that have done the same.

 

[yardie]

So for you people doing this swap, can/will the 1G Thermostat housing bolt up to the 2G head?

Still no response on this?

I have noticed that the 2G head has treaded bolt holes that appears that they may line up with a 1G t-stat housing bolt pattern, but I have not had both head and housing together to confirm this. If this is possible then that would eliminate the need for getting a 2G Thermostat housing and water pipe when doing the swap/retrofit!

Is there anyone here that can confirm or deny this?

 

[1SloColt]

Seems like there is a lot of good information and a lot of bad information in this thread. For people who actually make power and know people who make power and have tried different things, they would know that the only way a 2g head is going to out perform a 1g head is to have the 2g head heavily ported and keep the 1g head stock. The 2g head does have better geometric properties than a 1g head, but it still can't outflow it stock for stock. Fully CNC both heads and you'll see roughly the same flow numbers from both. The 2g head is structurally more rigid, and less prone to warpage. So if you are trying to make over 700, as I know so many people on this forum aptly do, then it'd probably be in your best interest to run a CNCed 2g head. If you aren't gonna make over 700 then I don't see any reason not to run a stock 1g head.

 

[bling5tatus]

So for you people doing this swap, can/will the 1G Thermostat housing bolt up to the 2G head?

You will want to use your 1g thermo housing on the 2g head... it's no big deal to do, I forget which head has the studs on the thermostat mount, but either way, just take the 14 (or 12?) mm bolts out and use them on the 2g head or find some 14mm nuts and put them on the studs in the 2g head to use the 1g tstat housing.

Now, for all the naysayers... I use a G6S head on my six bolt block. I switched to this configuration to pick up low end torque. Yes, it may choke at 600hp but not many people are making that much... AND I don't ever plan to make that much. A 2g head on a 1g block makes a GREAT combo for the street. When I swapped, I INSTANTLY noticed I had more torque and power down low... it was almost like increasing compression on the pistons. Yes, you do have to drill out the head stud holes to use the 2g head... I forget what size drill I used, but just make sure you don't leave any aluminum floating around anywhere. You'll know you're done when you can take a 1g head stud and it will drop right through the holes in the 2g head and have a LITTLE bit of play. I encourage ANYBODY that wants to have a better street car to try this combo. There are PLENTY of 2g heads laying around because everyone things that it's a genius plan to put a 6bolt in a 2g... which IMO is way wrong (look which blocks have the main girdles... hint: it's not the 6bolt blocks). The 2g's that were going to walk have walked, and the one's that haven't are sitting in some old lady that wear's purple sweat pants's garage in florida/california.

For those that are saying that a 1g head has the ability to flow more air, they are right, but when it is not close to that max amount of air that it can flow over a 2g head, it is inefficient in design. You guys saying that a 2g head is not as good have a LOT to learn. Intake velocity is what it's all about.

I know this is going to be hard for some of you to grasp and some will say it doesn't matter because it's on a motorcycle, but go read this article, then come back to the debate.

Homework

Who really needs the ability for their head to flow 700HP worth of CFM's on a car that makes only 380HP... that 380HP car would be FASTER if it were using a higher velocity/better port design head.

I would ALSO like to add that if you port the intake ports on the 2g head you are just undoing the whole bad ass part of having a 2g head w/ smaller intake ports. If you want bigger intake ports, don't ruin a perfectly good small port 2g head, just get a 6bolt head.

 

[kiggly]

I usually don't jump into threads that are as big of messes as this one, but I have a point to add.

The 2g head does NOT choke at 600hp. It also does not just accentuate midrange at the expense of top end. My race car has a 2g head on it, and with what I wouldn't call an aggressive port job. The port at the flange is stock size, untouched 2g and last season was on stock size valves. It makes about 1100hp at the crank and peak power with the 2.3l is at about 8400rpm. Yeah it is with big cams, but the head is still working in this rpm range.

I believe the 2g head is better overall than the 1g head. The port works well and it has better bracing and structure to keep head gaskets intact.

Kevin

 

[dsm-onster]

That is great information to know Kevin by some one who's been there and done that. Have you swapped between heads? Big power has been made with both heads. I think everyone wants to know what bolton makes an improvement (if any) and how much. I'm of the *opinion* that any difference wouldn't be even worth it. . . as long as the same intake manifold would be used between the two. I think that most of the advantage of the 1g head swap is the better stock 1g intake manifold option. It does have a larger plenum and wider, somewhat shorter runners.

Bling5tatus, why wouldn't you have gained more torque down low from longer narrower intake manifold runners? Instead of because head runners are smaller. The velocity arguement doent work. Slower moving particles in a larger area tube could fill a volume just as fast as a faster moving particls in a smaller area tube. It's not ALL about velocity. Intake velocity doesnt make power, airmass makes power. Which head delivers more airmass?

 

[awddsm95]

Kevin-

Its funny that you commented on this thread. I read through the first 3 pages and started to write a reply, then noticed that you had already made a post.

There is some partially correct information in some of this thread, but there is a lot of mis-information as well.

An intake port which has a larger physical volume does not always mean that volume flow (cfm) will be greater. In the case of completly bone stock 1g vs 2g intake port, a 1G head will outflow a 2G head at higher valve lifts.

Volume flow increase at the sake of reducing velocity is a very difficult trade off. Starting with a 2G head, you have the ability to create volume flow without sacrificing velocity at lower engine RPMs for given engine setups/combinations. Your desired max power RPM range, as well as engine configuration determines much of intake port design.

2G heads offer a much more consistent base to start with as far as the factory castings are concerned. There are some terrible inconsistencies with 1G castings.

I will suggest that both the stock 1G and 2g cylinder heads can work well with different opperating ranges. But If I were to start with a cylinder head, it would be a 2G, moddified as necessary.

 

[bling5tatus]

That is great information to know Kevin by some one who's been there and done that. Have you swapped between heads? Big power has been made with both heads. I think everyone wants to know what bolton makes an improvement (if any) and how much. I'm of the *opinion* that any difference wouldn't be even worth it. . . as long as the same intake manifold would be used between the two. I think that most of the advantage of the 1g head swap is the better stock 1g intake manifold option. It does have a larger plenum and wider, somewhat shorter runners.

Bling5tatus, why wouldn't you have gained more torque down low from longer narrower intake manifold runners? Instead of because head runners are smaller. The velocity arguement doent work. Slower moving particles in a larger area tube could fill a volume just as fast as a faster moving particls in a smaller area tube. It's not ALL about velocity. Intake velocity doesnt make power, airmass makes power. Which head delivers more airmass?

All that stuff aside, what happens when you put a large fmic on a small turbo... like a t25... you get a pressure drop that affects performance. "Larger is better" is a muscle car attitude and an old school way of thinking.

Visit the link I provided and go ahead and READ the info there... I think you will find that the 2g head has an upgraded port design and entry angle to the intake valves. Volume air flow can be had by using force induction... by why sacrifice low and mid range power so that you can have the possibility of flowing a few more up top. There is a good reason why the bean counters at Mitsu went to a small port design in the later models and in their race cars (evo1-3 had small port intakes and came w/ larger turbos /injectors than our usdm turbo mitsus did).

I have run both heads on the same block and DEFINITELY like the 2g head a lot more.

Kiggly racing even just posted that the 2g head is bad ass. The proof is in the pudding. I think it's a difficult debate to have unless you've actually tried both heads yourself and can say that one doesn't out perform the other based on your own personal experience instead of what you heard or what you think.... or what someone's "math" proves.

 

[dsm-onster]

I read your link. There's nothing there that negated the fact that you could have better throttle response and midrange from a manifold design that promotes throttle response and midrange. I'm not promoting larger is better. Please don't bring in for comparison the details of other automotive components that would be irrelevent*. Instead of bigger is better, I'm asking why head port velocity is better than head port flow other than choice of operating conditions and ranges How does more velocity lead to more hp than more flow would? Not negating Kevin's outstanding results and skill, how far has a 1g head been pushed? The proof is in the pudding?

awddsm95, the "modified as neccesary" part is what makes or breaks a head choice. For several reasons.







* Pressure drop increases with a larger intercool for a t25 but a smaller intercooler doesn't cool as well so the air is less dense. Either way, a maxed out t25 supplies and the motor receives 100% of the massflow between the setups. A whole lot of the pressure drop in a larger intercooler comes from the teperature change, since PV=nRT.

 

[bling5tatus]

Ok, I'm not a physics major, nor am I an engineer.... so I'm not in a position to debate velocity vs. airflow... but I will say this:

There is a reason that mitsubishi used an updated head design on their evo1-10 cars... and on their 2g turbo dsm's. Think about it... evo 3 car... 510cc injectors (larger than our usdm dsms), evo 3 16g turbo (larger than our usdm dsms), 9:1 mitsu pistons (higher compression than our 2g turbo pistons), timing rolled back in the ecu slightly.... and guess what the head was? G6K small port, w/ evo3 intake manifold (also small port w/ shorter runners than 2g turbo manifold).... why would they do this to their race cars in their home land? Put a small port manifold/head on their "fast" car? Why would they move away from using the large port head on our 2g turbos? Why do evo8-10's utilize a smaller intake port design despite still using the same 2.0L motor and higher compression pistons?

I can honestly sit here and say that the bean counters at mitsu knew what they were doing and did it for a very specific reason (and no, they didn't shrink port sizes to limit horse power or anything silly like that).

A 1g head can hold more volume... but it also takes more to fill that volume... same idea as the larger intercooler w/ a smaller air pump (turbo)... pressure drop is a lot. If you can get your power to come on sooner, you win the race... provided you can still flow air up top (a turbo will make the air flow up top). Kiggly has vouched for this on this very page.

If nothing else the 2g head is improved because of the angle at which the air hits the back sides of the intake valves is much less and not abrupt.

The school of 6 bolt is better is so 90s... and bigger is better is so v8s.

 

[dsm-onster]

Stay off the 6bolt/7bolt issue. You've never held both rods in your hand, nor then have you seen the difference in rod bolt diameter. You have not tested the metallurgy and tensile strength of each rod and rod bolt. A girdle is neccesary for jumproping, which isn't an issue until long after a 7bolt rod bends and even after the more sturdy 6bolt rod bends. As well, the 1mm larger head bolt diameter keeps the head on the block at the much higher cylinder pressures that the larger rods and better rod bolts can handle. If you want 500whp revving to 10K with no torque, then take a gamble with the light weight 7bolt motor internals with weaker rpm dependent rodbolts. Otherwise, if you want more torque and a better powerband for the circuit AND the strip, stick with a 6bolt. 'Proof is in the pudding'. There are 3 stock 6bolt motors I can name off the top of my head who have seen 600whp and recently a 4th that has trapped a 580whp speed with race weight mentioned in the holset threads.

The school of 6 bolt is better is so 90s... and bigger is better is so v8s.

Let's get more off topic. Speaking of school, STOP turning this debate into fads. Assigning chioce in technology to a decade 'is so highschool'. Rebok pumps may be newer but pf fliers were what set the records in baseball. It couldn't have been what's in the shoes. If you have nothing to contribute to the flow vs. velocity debate, or back to back comparisons, or authoritative sources proving one or the other, then STOP. Let show some maturity and actually give some benefitial input. . .



On topic. . .

Mitsubishi also went from small 2g ports with the 1.8 4g67 to large 1g ports with the later 1.8 4g67, so I don't see the point in your arguement . Evo 10s? Show us a comparison to see the similarity of head port design?

A 1g head can hold more volume... but it also takes more to fill that volume... same idea as the larger intercooler w/ a smaller air pump (turbo)... pressure drop is a lot. If you can get your power to come on sooner, you win the race... provided you can still flow air up top (a turbo will make the air flow up top). Kiggly has vouched for this on this very page.

^^^I agree that you are unclear on the physics of the topic. How fast does it take a turbo to fill the difference in volume? Your intercooler debate is false. I will beat you with a larger intercooler because my aircharge is more dense and less work is done by the cylinder to compress the aircharge for the same massflow. As well, I will never be shifting into a rpm range where t25 is still spooling no matter the size of the intercooler. Let's jsut stop talking about intercoolers and get back onto port design!!! Smaller 2g ports havn't been proven to increase low end power. Long thin intake manifold runners tuned to lower rpms have. Your swap consisted of ditching the 1g intake for the 2g intake, not just heads. What has the 1g head done again?

If nothing else the 2g head is improved because of the angle at which the air hits the back sides of the intake valves is much less and not abrupt.

It all has to go past the same diameter and shape valve/seats How about that angle? Do you know why there's a rise at the 1g port? Could tumble be involved? What different benefits are there to increased tumble?

Look. I have replied with much more questions than anyone else here. These questions and those asked by others are the ones needing to be answered. No one needs unfounded statements of guarantee, nor choice classification. Compare and report. Otherwise, what's the use of swapping parts? There's no proof one works over another.

 

[bling5tatus]

How about the butt dyno says the 2g head is faster w/ the same setup... I'm not one to dyno a car.. .because i don't care about numbers games.

I have run both heads on the exact same setup... 2g head FELT like it had more acceleration.

So... based on what you're "arguing" for here... Mitsubishi made the wrong choice in changing intake port size on all their late model race car heads?.... or was the velocity the better choice over the plenum/port size?

Before boost comes on, small intake ports offer more low end torque... Why would you not want to hit boost faster again? Call me crazy or not a basketball shoe expert or whatever, but I would have to say that spooling a couple hundred rpms sooner based upon intake velocity alone would win a race on two cars w/ the same VE related parts aside from the heads.


You should maybe go sell them some of your ideas, i think you may be able to make their cars even better than the japanese engineers can.

I ask that you continue using 6 bolt heads because that means I can build more motors w/ small port heads. 6bolts are better because volume is better than efficiency and velocity...

Wait... Mitsu went to smaller design on their late model cars... maybe they don't know what they're doing and they can get more out of more volume? Fail.

 

[dsm-onster]

How about the butt dyno says the 2g head is faster w/ the same setup... I'm not one to dyno a car.. .because i don't care about numbers games.

You_swapped_manifolds_when_you_swapped_heads. . . Longer thinner runners found on the 2g intake manifold are proven to increase spool and low end power across the board on all platforms. It's called helmholtz tuning. This is the 3rd post Ive said this. You have NOT done a direct swap with the same setup. Log and tell us what your difference in the topend is.

You may not care about the numbers game, but those that want a certain trap speed and et do. That's why we have these questions.

I'm not telling you why mitsubishi did anything in these last posts. I'm asking you why I should swap to a 2g head? I want as much power as what the 1g head has put down. You've provided no input on the subject or asked any questions yourself.