2G head = more hp?

[Daedalus]

I need your help on this one guys. No one has ever done this project and we just need some general thoughts and information on the differences in 4G63 heads.

*PLEASE DON'T Move this to the N/T Forum... IT WILL NOT GET READ!!!*

For a NA 4G63 application would it make sense to use a 2G head and intake manifold rather than a 1G head and manifold because the ports are smaller thus increasing port flow and power (at least on a NA platform). I know its the opposite for turbo's, that larger is better, but we are wondering (and leaning towards) that a 2g's head will have better characteristics on a NA application.

Please just post your thoughts on that only. No N/T - Turbo wars. If you want to bash me, do it in PM!!!

Hypothetically it does make sense that it would have a positive effect on NA engine performance right???

Thanks for all of your help. You guys are probably the only people that could help sort the facts out here.

 

[TD05HTalon]

a 2g turbo 4g63 head on a 1g NT 4g63 block correct?

At least the 1G turbo and non turbo 4g63 blocks and heads are basically the same with different rods/pistons, and cams. The blocks are the same just without oil squirters on the NT's.

I guess it would fit since you can put a 1G head on a 2G block with a little machine work to make the head studs fit. I'm pretty sure the 1G head bolts or ARP studs are a little thicker so you might have to bore out the holes for them on the 2G head a little for clearance.

Also depending on what year head you use - a 95/96 head does not use a CAS - there's a sensor on the crank. If you used a 97+ head that did have provision for a CAS you could probably get the wiring to work or just use a 1G CAS in place of the 2G one.

The 2G manifold uses a MAP sensor so you would have to weld a little cap or make a blockoff plate for it.

A 2G manifold also mates to the 2G throttle body which is smaller than the 1G one so you could either bore the opening to accept the 1G body or find a way to use a 2G one with the 1G sensors if they would fit.

As far as power gaines I really don't know much about the flow characteristics of a NA motor. I imagine the smaller ports might increase velocity a bit and since the 2G manifold and head were designed to make more low and mid range power it could work. The 1G head and manifold are large to make more top end power but sacrifice mid range torque (of course this is with factory turbo and such). I'm pretty sure the valves are the same size for all the motors so that probably won't make a difference in piston clearance and such but you'd probably have to check that.

I'm done rambling but i hope something i said has a shred of usefullness. If you decide to go ahead with the swap let me know - I'd be interested to hear about it.

 

[Daedalus]

It would be a 4G63 Head bolted onto a G4CS (2.4L) block with 11:1 compression. We think the valves will work fine, but we weren't sure about the CAS, and to be honest hadnt even considered it. Port velocity and torque are two of the largest things being considered on this buildup.

If we can get a 1G intake manifold (So we can retain the big 1G throttle body) to mate with the 2G head that would be perfect.

THANK YOU VERY MUCH FOR YOUR POST! IT HAS HELPED A LOT!

Anyone else?

 

[TD05HTalon]

Here's an update: I was looking around and this link might be interesting to you :

here

Scroll down and look at the Level 5 "death" cylinder head - it's a 2G one and they explain why it's the best head.

 

[DSMeclipse4G63]

stock vs stock the 1g head will flow more for slightly better top end, while the 2g gives great low end and mid range power. The 2g head is mapped out better then the 1g head, with the 1g head all you can do is port it out more, but a 2g head with similar runners and porst as a 1g head will create more hp. Now you say you want the top end of a 1g head, well since we have hemispherical combustion chambers, we can create high toque, high revving, with great top end...and thats the just the combustion chamber with it ported out it will flow more top end then a stock 1g head. It all depends on what your application is, for drag racing a ported 1g head will probly be your best bet, while the 2g would be better for other types of racing and street use. I personally will be using a ported 2g head over a 1g, but thats just for my style of racing.
Andrew