2g to 1g head conversion. Worth it?

[rad_dsm]

I know the 1g head has bigger ports and should flow more but I was wondering if anyone has ever done a comparison between them.

Does anyone know if anyone has ever done a comparison between the 1g and 2g head?

If anyone knows of any links I would appreciate it.

Thanks

 

[tibby_boy]

stock the 1G head is better because it has bigger ports, more top end. the 2G is better if built because the port velocity is better. also the stock 2G head has better low end torque. here is a link for the search results.
http://www.dsmtuners.com/forums/search.php?searchid=1460368
hope this helps.

 

[blackGSX2g]

Here is a visual:

stock 2g head

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my ported and polished 1g head

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[ericbev]

The size of the ports isnt everything guys. There is alot more to it. Jim knows his stuff. Figured id post what he said instead of linking.

What sort of scientific proof has "look at it" been turned into? What makes you think that you will gain HP with a 1G head over a 2G head just because the intake runners are larger?

The larger runners on a 1G head have a much larger angle into the valve, this actually slows the air entering the cylinder chambers. Generally on a port job of a normal head for racing they raise the chambers not lower them so the entry into the valve is a straight as possible. The angle into a 1G head is horrible because the port is so low already in the head.

The HP increase from a 2g head to a 1g head is from the Cams, and Intake manifold. If your using aftermarket cams and plan on buying a SMIM don't put on a 1g head because you'll end up with no gain and a head that has horrible port design.

Most major racers now using DSM's are using a 2G head and 2g style intake manifold and raising the runners in V8 styles so the air is hitting the top of the valve as straight on as possible. Air flow has nothing to do with the size of the chamber and EVERYTHING to do with the shape and design.

Putting a 1g head on a 2g block is the OPPOSITE of what you want to do. Replace your 2g block with a 1g block and keep your 2g head. Have it ported and port raised and add a set of HKS or Comp cams with a SMIM. This will provide you with a much more potent street engine.

Also AMS Eric 2.

Originally Posted by AMS Eric #2
Use the 2g head!! The castings on 2g heads are far superior to 1g castings. They have more alluminum in the lifter bulkhead to reduce flexing and less problems with casting shifts than 1g heads. The intake ports are smaller yes, but they do not seem to be a restriction of any sort. The Evo 8 heads have the exact same intake ports and we are making 600+ whp constantly on completly stock unported ones. Our shop car's intake ports arent opened up that much at all and it makes over 800 awhp.

Use the 2g head, drill the head bolt holes out to fit the larger 12mm studs, find yourself an Evo 3 intake manifold, and you'll have the same top end package as an Evo 8, which has been proven to consistantly outperform 1gs. It will save you money, make your swap far easier and WILL outperform a swap with a 1g head/intake, much to everyones dismay.

I just copied this from one of my posts 3 days ago. Like stated above, there are alot of these threads you can dig through.

 

[1GenDSM]

The 1g head is better if you wanna keep a stock top end. as tibby body said. And if you are more about wanting to mod the head you will want a 2g head. just so you dont have to read all of that.

 

[my98GST]

I'm thinking about putting my buddies 1g built head on my 2g... I know there are some other parts that would be needed to accomodate and make the conversion worth while like 1g TB, 1g IM, 1g water pipe, 1g thermostat housing... Is doing the conversion going to be any different than a 2g head with the same mods? Manley valvetrain, Fp2x cams, ported...

 

[1g_tsi_awd]

What isdone to this 1g head?

Because usually 2g valves are bigger... So it wouldn't make a lot of sense...

 

[JayRolla]

Well if its built then yea its worth it, expecially if you get a good deal.

 

[mjarrell20]

Is it a stock 1g head? If so it's definitely not worth the trouble.

 

[1g_tsi_awd]

Or you could use the money instead of buying the built 1g head and build up your 2g head...

 

[my98GST]

It has manley valvetrain, FP2x cams, and has been ported. Im asking what are the differences between the two heads. If both a 1g head and a 2g head both had the same exact mods such as these which one would out perform the other?

 

[JayRolla]

I wouldnt think so. If it was ported with a flow bench and done correctly it can cost up to $400 or more just for porting and is a very nice upgrade. If you are getting a good deal buy it. I guess if its a 1g head you can set it up so you can adjust your base timing I think.

 

[MyBeatGSX]

Straight from RRE:

Why do all this? The 2G car has a little honda sized throttle body, intake manifold, and intake ports. That is one of the big reasons the 2G's have better bottom end power but are a little slower at the drag strip. Example: 1G intake port at the gasket is 60mm x 37mm, 2G measures 56mm x 28mm.... ouch! Throttle bodies are 1G - 60mm vs. 2G - 54mm While a 1G head and intake manifold flow more than a 2G head and intake manifold, too many people are in a big hurry to do the swap when they have not maximized their current set up. Even a Cali car can run well into the 11's on a stock 2G head and intake manifold. A well ported 2G head and Extrude Honed manifold will take you even further. If your 2G head dies a horrible death from a suicidal T-belt, go ahead and do the swap while you are fixing things up.


Some guys want to just install a 1G manifold on a 2G head. The port size between the two is quite different, you cant just bolt it on. The 2G head _can_ be ported to flow as much or more than an unported 1G head. But if you can get a decent deal on a 1G head why bother ? I have seen some butchered up 2G heads with the 1G Look that were a waste of time to bolt on. Just because you make it huge at the gasket mounting flange does not mean it will flow any better. The real HP gains are made deeper in the runner and the bowl area where it is harder to get to.


The 1G cams have .010" higher lift. and are an upgrade by themselves.

 

[my98GST]

It's got ARP head studs, Fp2x cams, Manley valvetrain with only 70 miles. It has two bent valves from where he threw a rod bearing it jared it so bad that it bent them, not badly but when water tested it showed that there was valve damage. He said 600 bucks....

 

[JayRolla]

if its just two bent valves I would buy it for that. Low ball him and see what he says. Also make sure its just two slightly bent valves and also make sure those parts are actually in it.

 

[my98GST]

Yes I know each head has their advantages and disadvantages.... My plans with the whole thing is 400whp on the motor and then having meth/water injection as well as a little 50 shot of n20... I will be putting Ross pistons in, eagle rods, arp hardware yadda yadda yadda....

I want to be reving to aroudn 9000 on hks 280's but I just don't realy know which head would be more suited for a daily driver that loves to have the piss beaten out of it. I'm going to go also with a Magnus IM.. Any help or suggestions or opinions would be greatly appreciated.

 

[beating4g63s]

either head will support what you want, I personal choice would be 1g head just because I have 2 of them laying around and don't really plan on passing any type of hp number to really worry about weather going one way or another which my plans are around 400-450hp so yeah your fine if you buy a 6 bolt motor and retain the 1g head.

 

[my98GST]

I've got a 6 bolt block just got to reasemmble and everything... I think the 2g head on the 6 bolt is easier to swap and everything but I just want more power .

 

[ECLIPSE4x4]

If you want to be reving that high you better look into some upgraded valve springs.

 

[my98GST]

oh of course, i'm goign to go with SI duals with manley retainers with JAM +1mm nitride valves wtih hks 280's

 

[ECLIPSE4x4]

well then since you have a 2G head, and you are going with a SMIM then just use it.

 

[my98GST]

so i'm not going to see any real major comparable differences between the two built idetically the same?

 

[pooker]

I was always under the impression that the 2g head cost more to work on, while noticing more gains with it most people don't get to that point of needing something like that. So they choose the 1g heads because they are cheaper. I am using the 1g head as well though in my build.

 

[playitlouddsm]

What cost more about the 2g head? To fit it on the 6 bolt block all you have to do it bore out the head stud holes to 12mm. Since the head should be at a machine shop anyways to get cleaned before you put it together, boreing out the stud holes won't cost much more.

 

[Spoolin98]

I think what he meant by cost more is to have a 2g head flow as much or more than a stock 1g head. Stock for stock, the 1g head unported will flow more than an unported 2g head. But if you want to get into spending some extra cash on porting, the 2g is your pick. The 2g head has more metal in the runners to work with allowing for nice port job that flows more than a 1g head ported. IMO, if your not porting, stick with the 1g head. If you are porting, def. go with a 2g head.