The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support Rix Racing

Hi Velocity or Hi Flow head for HX40?

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

1990TSIAWDTALON

Moderator
11,399
8,039
Nov 14, 2013
Independence, Kansas
Ok here is a much debated question. I have a 6 bolt motor, 10:1 Manley pistons, Kelford 264's, Eagle crank, Manley rods, balanced. I have two different heads I could use on this motor a 6 bolt or a 7 bolt, so do you guys think a High Velocity head like the 7 bolt is better or is the High Volume 6 bolt head the one that should be used in this build, I have both and need some advice. I am running a 1G TB, Wally 255, FMIC, FP manifold with a Holset HX40, speen density and water meth because of the compression. Thanks in advance for some much needed advice from someone that has been there and done that.
 
Not being a smart ass here but if your 7 bolt head is from a 1g you have the same ports as the 6bolt head. The only 7 bolt head with the smaller ports is a 2g head.
 
Yes the 7 bolt head is the smaller port hence Higher Velocity. Keep the comments coming. Thanks Kyle. I was leaning towards the smaller port head, and I'm not planning on hitting huge hp numbers but when I got my car it had a 1990 intake bolted up to a 2g head which when I took it apart, showed how the mixture was basically hitting a brick wall at the head since the intake was large port and the head a small port...what a work of art by the PO. I swear everytime I turn around, something on this car is mismatched, put together wrong and on and on so I want to "save its life" and get her on the good side, thats why I needed some comments and feed back and DAO I understand, you were just commenting with information, so thanks.
 
I'm a big fan of both worlds (thanks to the Cyclone IM)! I swear that my old H1E spooled faster with it than my E16g did with an extrude-honed 1G IM! -This way, I get the intake velocity of a 2g head & the high volume of a 1g head after the secondaries open... Something to consider
 
Thanks Vic, I am getting good feedback which is what I was needing. Keep it coming with comments, I am open to all. So BoostedTalon, are you using a 7 bolt smaller runner head and what size is your intake manifold runners? Do they neck down to give you the higher velocity into your head and it works good for you? Thanks.
 
Thanks Vic, I am getting good feedback which is what I was needing. Keep it coming with comments, I am open to all. So BoostedTalon, are you using a 7 bolt smaller runner head and what size is your intake manifold runners? Do they neck down to give you the higher velocity into your head and it works good for you? Thanks.

I'm not. I'm running a 6-bolt large runner head with a Cyclone intake manifold... "half" of the runners of the Cyclone are normally closed (to mimic the smaller runners found on a 2g head), but open up at my switch over point that I have set within DSMLink (providing the volume of a 6 bolt head). You can see the flappers (open) in the pics below for a better idea
 

Attachments

  • IMAG0002.jpg
    IMAG0002.jpg
    265.4 KB · Views: 180
  • IMAG0003.jpg
    IMAG0003.jpg
    298.6 KB · Views: 168
Last edited:
Well thats some cool s*%$!! Now if you were in my position without a cool intake and had to choose, what would you do. I have my choices but once started have to stay with it. 2G head and intake (ported for my 1G TB) or 1G head and intake. I am not going to make super high horsepower and of course want the best of both worlds which never seems to work. Suggestons are always welcome so I can make a choice. Running 10:1 with water meth, 264 Kelfords, Eagle crank, Manley Rods, Manley ceramic coated pistons, FP mani, with the Holset HX40 8 blade. Thanks!
 
The 1g/2g small vs large intake port argument may be a bit misconceived, similar to the argument of 6 bolt vs 7 bolt, which has nothing to do with the number of bolts holding the flywheel on.

You might note that new high HP engine designs have the intake ports parallel with the valve stem... straight shot for the airflow. The 1g large port head adds volume at the bottom of the port before the "big turn." Filling the cylinder seems to be more efficient when the air doesn't take a 90° corner right before the valve head. The air traveling at the bottom of the 1g intake port doesn't magically turn 90° and enter the cylinder at the "early side" of the valve. Moreover, the air at this bottom edge "jets" off the port lower surface "like a car flying off a cliff" this stream of air from the bottom ledge now mixes with (disturbs?) the "ideal stream" following the top surface of the port.

None of this has much to do with the intake manifold design. It is the design of the intake port in the head.

Both heads work... yes. Again, new high HP engines seem to be designing heads with intake ports aligned with the valve stem. This may allow a more even flow distribution to the valve.
 
Nice writeup, i will have to make a choice and your writeup is a good point to put out there. Thank you!!
 
Talon dave switched to a 2g head es. But he also switched cams. I cant remember if he went with the Kelfords or the GSC cams. and he also switched coilovers. So saying he went 9.12 from just the swap is wrong. There where a few other things swapped at the same time when he ran the 9.12
 
Guess I just need to pick my poison.
 
I've noticed a trend of more and more of the fastest guys using 2g heads. I'm sure this is not just because they had one sitting on a bench somewhere collecting dust. My machinist was telling me about 6 months ago about all the reasons they have found why the b18 gsr head is better when conventional wisdom was that the b16 head, which is very similar to a type r head, is better.
 
I've noticed a trend of more and more of the fastest guys using 2g heads. I'm sure this is not just because they had one sitting on a bench somewhere collecting dust. My machinist was telling me about 6 months ago about all the reasons they have found why the b18 gsr head is better when conventional wisdom was that the b16 head, which is very similar to a type r head, is better.
Its due to its ability to be ported and shaped in a way that better promotes cylinder filling. the 1G intake gyometry is not the greatest. This is why Honda's are able to punch out massive HP numbers on low boost. They have a head that flows so ridiculously better than ours. 1G heads have been pushed far same with 2g heads. Just wished mitsu spent more R&D on them like honda did
 
Love the reply's, please chime in with your 2 cents!!! Thanks Guys and Gals!
 
Why bring up what "so and so" did? This is, the same as many other questions, a matter of personal preference. Why not, if you have the know how and the heads sitting around, install and try both.... then YOU decide what you like rather than asking the internet for their opinion. I see a lot of people replying in here that haven't actually used both heads on their own and are going of what "so and so" did. I'm not trying to be unhelpful here, i'm trying to get you to change the way you're thinking about your car mods.

I remember a time when there were some "really sharp", cough cough, gurus here arguing that the 1g head was far superior.... turns out that after much trial and error the tables seem to have turned and we have a split decision rather than the "bigger is better" mentality.

If you choose the 2g head, make sure you have adequate clearance for the head's oil feed from the block or else you'll be putting that 1g head on in short order.

94AWD Coupe actually filled a cyclone intake in w/ epoxy to make it mate properly to a 2g head..... and said he loved it. If you listen to what other people tell you to do when they haven't done it themselves, you're just being the blind following the blind.
 
Why bring up what "so and so" did? This is, the same as many other questions, a matter of personal preference. Why not, if you have the know how and the heads sitting around, install and try both.... then YOU decide what you like rather than asking the internet for their opinion. I see a lot of people replying in here that haven't actually used both heads on their own and are going of what "so and so" did. I'm not trying to be unhelpful here, i'm trying to get you to change the way you're thinking about your car mods.

I remember a time when there were some "really sharp", cough cough, gurus here arguing that the 1g head was far superior.... turns out that after much trial and error the tables seem to have turned and we have a split decision rather than the "bigger is better" mentality.

If you choose the 2g head, make sure you have adequate clearance for the head's oil feed from the block or else you'll be putting that 1g head on in short order.

94AWD Coupe actually filled a cyclone intake in w/ epoxy to make it mate properly to a 2g head..... and said he loved it. If you listen to what other people tell you to do when they haven't done it themselves, you're just being the blind following the blind.
While i agree with this, some people dont have time, or reaources to do sich things and would rather do whats proven once. But I'm all about pioneering.
 
Understandable. I vote for the 2g head... with an evo 3 manifold or an aftermarket manifold made for it.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top