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1g head vs 2g head

turbo tim1

Proven Member
158
1
Sep 16, 2010
blackfalds, AB_Canada
I have read that the 2g cylinder head flows more air than the 1g head despite the larger ports of the 1g head.

If both heads were ported which one would flow more.

I have a mix of dsm parts, enough to throw an engine together so I was thinking of building a project Frankenstein, a 4g64 block with 2g pistons 1g rods and possibly a 2g ported head, depending on which head flows more.:hellyeah:
 

DSMReviver

Proven Member
1,131
74
Mar 4, 2008
Little Rock, Arkansas
2g will flow better in stock/small turbos. If you are upgrading to bigger turbos, 1g big ports are suitable.

If both heads are ported i would still take the 1g head. 1g heads are already design that way to take in more air volume for bigger turbos and the angle geometry is already calculated with the increase port. I believe if the 2g runners are ported, they will loose their intake volume angle and will distort the flow. But im sure if you port the 2g's out, you will see a benefit of larger volume intake but only up to an extent. But both head are good for a specific needs. im running a 16g turbo right now and i would love to have a 2g head(flow velocity is amazing) but if i go bigger like gt35r/holset hx35,40/gt40r i would want 1g.
 

NeMiZiS

Supporting VIP
2,099
34
Jul 25, 2007
Palmer, Alaska
From what I've read the 2g head is supposed to be a better design.
It seems like the 1g head would flow better, looking at the picture.

images?q=tbn:ANd9GcQcFJfLserWUXavEIuF4lSCUirb6OPgI5ezPuCsKlxC71oe2Ztd&t=1.jpg
 

VETTE_50_TH

Proven Member
3,744
20
Jun 24, 2004
Columbus, Ohio
Ive read some good and some bad. I dont think anyone has ever done real testing on either one that could be used as fact. Im glad its that way, because prices of certain heads would depreciate so much that all of them would go to the junkers and one would sky rocket. But i know one thing, the 2g oiling system is ####ing retarded.
 

LiquidX

DSM Wiseman
8,304
108
Sep 19, 2008
Anywhere, Pennsylvania
2g has higher velocity than the 1g. It has been discussed that the 2g head is a better overall design and has taken cars into deep numbers.

I'm currently at an estimated 450-500hp via ECMlink v3 on an un porter 2g head with an Evo3 intake manifold so take it for what it's worth.

The numbers are not stating what the car is really producing as it has not been dynoed.
 

m_0ney_pit

Proven Member
769
45
Jan 12, 2007
Reading, Pennsylvania
2g head is will flow air faster(higher flow rate) in relation to the 1g. choice will depend on your mass of air being flowed as said above. for most people the 2g is better.
 

DSMunknown

Proven Member
4,110
35
Sep 16, 2004
Worcester, Massachusetts
IDK why people spew shit out when they don't know what they're talking about.



kiggly said:
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
 

spawn87

Proven Member
907
2
Dec 6, 2007
sacramento, California
well im not going to say the 1g head isnt good but since my car is a 2g and its a DD in california i wanted to build an engine that was "legal"

the logical choice for bottom is the 6bolt and the 1g rods.
for the head i went with a mild ported 2g build head with the 1g tb and 272s.

biggest choke point is the tb and the flange on the 2g manifold. you port that and go 1g tb and that is already making up in runner size and further increasing velocity. you want more top end go with the evo3 manifold. point is i read for about 1 month almost all benefits and cons to going ether 1g or 2g head and in the end i choose 2g head. take it for what its worth but my engine feels pretty good plenty of power in mid and top range (enough to get away from those hondas and disappoint those mustang gt on the long run) and i havent even gotten the car tuned yet.

at the end of the day it all depends what you want the engine for and what its going into.

both 2g and 1g heads have their benefits you just have to see if the benefits suit your goal.
 

turbo tim1

Proven Member
158
1
Sep 16, 2010
blackfalds, AB_Canada
Sounds like no one has flow bench tested either head against each other, I will probly go with the 1g head because of the volume difference in port size.
 

daren_p

DSM Wiseman
4,609
86
Nov 22, 2004
Newmarket, ON_Canada
Sounds like no one has flow bench tested either head against each other, I will probly go with the 1g head because of the volume difference in port size.


Please see post #7 above, if you don't know who Kiggly is, please google/youtube the name. I'm pretty sure the "smaller" volume in the 2g head isn't an issue for most DSMers :shhh:

Both heads work, take your pick for what best suites your application/needs.
 

1AWD90

Proven Member
134
0
Sep 6, 2007
Marshall, Minnesota
I have flow bench tested stock 1g head and also again after I ported, polished and went to 1mm oversized valves. I have the numbers at home if anyone is interested in seeing them I can post them tonight. However, I have not tested a 2g head. I have always had 1g heads at my disposal so that is what I have used. I have always seen nice gains in porting a 1g head but it all depends on if you want velocity or volume.
 

turbo tim1

Proven Member
158
1
Sep 16, 2010
blackfalds, AB_Canada
I have flow bench tested stock 1g head and also again after I ported, polished and went to 1mm oversized valves. I have the numbers at home if anyone is interested in seeing them I can post them tonight. However, I have not tested a 2g head. I have always had 1g heads at my disposal so that is what I have used. I have always seen nice gains in porting a 1g head but it all depends on if you want velocity or volume.

Please post the numbers I would like to see the difference in flow from stock to ported.

Hopefully some one has done the same with a 2g head, I would like to see and compare numbers rather than basing a decision on hear says and speculation.
 

99gst_racer

Moderator
11,796
971
Apr 5, 2003
Coloma, Michigan
The whole idea behind the design of the 2G head, is that it's a "raised port" design. This helps with air velocity, which can improve low-end HP and torque. Potential benefits include:

* The higher the air flow speed, the better the air/fuel mixture is atomized. This improve the combustion process.
* The higher velocity improves the combustion chamber 'swirl'. The 'swirl' distributes the air/fuel mixture in the combustion chamber, improving the combustion process.
* The higher the velocity, the greater the inertia of the air flow. This helps fill the cylinder to its maximum, improving the VE (volumetric efficiency).

The vantage point the incoming air has to the back of the intake valve is sometimes referred to as the angle of attack. Due to its added height, a raised-runner head simply has a better angle of attack or vantage point for a straighter shot to the back of the valve. The added height also reduces the angle of the turn that the incoming charge must negotiate. The geometry of a raised-runner port is superior to a similar nonraised runner design, since it allows additional airflow and a higher terminal velocity before it stalls or backs up.

I believe if the 2g runners are ported, they will loose their intake volume angle and will distort the flow.
That depends on how it was ported. Any decent cylinder head porter will tell you that it's not a matter of just hogging the port out larger. It's performance greatly depends on where the material is removed and the overall shape of the port. Without getting into details about the port shape, the proper way to port a 2G head runner it to remove material on the ceiling of the port and leave the floor alone for the most part.
 

99gst_racer

Moderator
11,796
971
Apr 5, 2003
Coloma, Michigan
Sounds like no one has flow bench tested either head against each other, I will probly go with the 1g head because of the volume difference in port size.
A good friend of mine has a performance shop about an hour away. He's a DSMer and is very good with head work (he does my head work on my 2G). He's in the process of building a 1G head that has a different scenario for each bank. It ranges from stock, to mild and aggressive porting, to oversized valves and bowl work. He's going to flow bench each bank and see where and how much the improvements are. And as soon as he can locate a junk core 2G head, he's going to do the same with that. So, be on the lookout for test results to be posted here sometime this spring. :)

Once and for all, we'll know how each compares to the other.
 

2slow4now

Proven Member
1,312
37
Nov 20, 2008
somerset, Kentucky
If you don't have a flow bench to test what grinding/hogging out needs to be done then the best you can do is just do a mild cleaning up of the ports and port match everything. Just make clean smooth transfers for the air to follow from the intake thru the head and out the exhaust.
So 1g or 2g head? Either cleaned up a bit will do fine. If you want anything more than smooth flow then you have to get serious. Flow bench, a test head or two to experiment on, make sheet metal templates when you get the flow numbers, lots of grinding and matching each port with the template you made. Or take it to a shop that does our heads and fork out the cash.
+1 on 99gst racer and every body else LOL
 

VETTE_50_TH

Proven Member
3,744
20
Jun 24, 2004
Columbus, Ohio
A good friend of mine has a performance shop about an hour away. He's a DSMer and is very good with head work (he does my head work on my 2G). He's in the process of building a 1G head that has a different scenario for each bank. It ranges from stock, to mild and aggressive porting, to oversized valves and bowl work. He's going to flow bench each bank and see where and how much the improvements are. And as soon as he can locate a junk core 2G head, he's going to do the same with that. So, be on the lookout for test results to be posted here sometime this spring. :)

Once and for all, we'll know how each compares to the other.

Ive got one if you want to pay to ship it. :thumb:
 

knochgoon24

DSM Wiseman
6,139
76
Jan 29, 2008
Troy, Michigan
A good friend of mine has a performance shop about an hour away. He's a DSMer and is very good with head work (he does my head work on my 2G). He's in the process of building a 1G head that has a different scenario for each bank. It ranges from stock, to mild and aggressive porting, to oversized valves and bowl work. He's going to flow bench each bank and see where and how much the improvements are. And as soon as he can locate a junk core 2G head, he's going to do the same with that. So, be on the lookout for test results to be posted here sometime this spring. :)

Once and for all, we'll know how each compares to the other.

Maybe he could throw info on the Hyundai head in there too. He probably doesn't need to flow test it, but just having all the head info in one place would be nice.
 

turbo23

Proven Member
351
11
Oct 25, 2005
Shelbyville, Michigan
I accually thought i had my hands on a hyundai head, but that fell through.. Since i havent done the testing yet, I'm not sure which head will flow better.. There are tons of variables to consider with choosing a cylinder head. So much so, that covering all the bases would just lead to more questions. Like for instance:

- Engine volume
- Engine rpm
- Camshaft lift
- Camshaft duration
- Pistons speed at crank angle and valve lift
- Rod ratio

All these should be considered, and much more. its all about the combo.

For what most people are doing, I would agree that the runner volume of the 2g head is better suited..
 

VETTE_50_TH

Proven Member
3,744
20
Jun 24, 2004
Columbus, Ohio
Can you tell me which i need then if i tell you all the answers to your questions?

Also, turbo23 now has his 2g head for the flow tests.
 

turbo23

Proven Member
351
11
Oct 25, 2005
Shelbyville, Michigan
If you give me stroke and bore, valve lift, cam duration @ .050 and advertised (@ .020). i'll be able to tell what target rpm is, also what intake and turbo. IMO the 2g head will be better suited for 99% of the combos i've seen.

I'd like to do a back to back test on a 1g head and a 2g head, and look at the power band and total output differences. I still wonder how much of an affect air density has on cylinder head choices, and also back preassure as well. Like I said, its all about the combo. Just because a head flows better, doesn't mean it'll make more power.
 
Last edited by a moderator:

turbo23

Proven Member
351
11
Oct 25, 2005
Shelbyville, Michigan
I'm assuming its a 1g manifold, better idea would be to fill the intake to match the head.. imo anyway
 

ramsack

Proven Member
3,286
16
Dec 27, 2007
West Lawn, Pennsylvania
An even better idea would be to just sell that intake manifold and get the 2g version of it. Most companies that make them have 1g and 2g manifolds available.
 
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