1G intake man / 2G head?

[my98gsx]

I am currently doing a big rebuild on my 2G gsx, i put crowler valves, web 272 cams, cam gears, crowler springs/ret, and all new seals ect... I port matched my head to the 2G intake manifold gasket... Once i got my head home from the machine shop my friend gave me his 1G intake manifold. ( which is much bigger than my ported 2G manifold is... ) Can i use this instead of my stock one? ( even though the head isnt port-matched to the 1G... will it flow more to the head than the small seconed gen? )

 

[Rob10_99]

ok stock on stock,
1g = huge ports
2g = small ports (almost half the size I would say)

now if you gasket matched both to the 1g gasket it will work,
have any pics? a ported 2g head is the "best" to use because of
more efficient chambers, but takes a lot of porting to match it to the 1g intake.

 

[CanadianTSi]

Can i use this instead of my stock one? ( even though the head isnt port-matched to the 1G... will it flow more to the head than the small seconed gen? )

Half of the Air will be slamming into the head because it isn't port matched, do you think this will be good for Horsepower?

 

[my98gsx]

i dont think so but the stock manifold is so restrictive... im thinking about hitting the head again and opening the prots up to the 1G gasket... i dont know if theres enouph metal to open it up that much i dont want to break anything....

 

[CanadianTSi]

It can be opened up enough but then it really messes with the angle at which the air hits the valve's.

 

[Talesin]

There's enough room to port and match to the 1G manifold runners. And if you do a good job, it shouldn't detract *too* much from the 2G head's flow.
Still prefer a 1G head myself. Not as efficient a design for runner scavenging, but quite a bit more air can get through. Same problem as going to a 3" exhaust, really.

 

[my98gsx]

so if i ported both the head and the intake of my 2G stuff, you would just leave it? What would you all recomend me doing... porting the crap out of the head again to match the 1G, or just live wit the 2G parts?

 

[CanadianTSi]

I'd stick with your 2G head/Intake and just get a SMIM down the line unless you want a 600+whp beast then I would do the 1G head swap.

 

[my98gsx]

im trying to get the most out of my rebuild... so if the port work would help me out that little bit extra i dont mind doing it... my car blew up in october and im just finishing it up now. Its a 2.3 stroker with everything in the lower block aftermarket, and the head was completly done with high flow valves, port work, and a competition valve job, so it should flow alot better than stock. i just figured it would build more power with the massive runners on the 1G manifold...

 

[Talesin]

The problem is the turbulence generated by the 'step' between the intake manifold runners and intake ports on the head. Think of it like a waterslide. You want as much velocity and as little churn as you can get, so a smooth transition is needed. Just take the 1G manifold gasket and have your machine shop port the intake ports to match, size-wise. There's enough material to do it.
The theory behind head design is complicated and a bit of a pain. You have three real options, as slapping a 1G intake manifold onto a stock-port 2G head will more likely result in *less* power than a 2G manifold on the same head.

1) 2G Head, 2G manifold, port the throttle body area and switch to a 1G TB. Just take a 1G gasket and port out the inner area, making sure you get no metal bits inside. Your shiny engine won't like them.
2) Ported 2G Head, 1G manifold/TB. You'll flow nicely, but really need to do this before the engine is assembled for best results. Many people say that the 2G head flows more efficiently, but I've never seen any quantifiable results from a flowbench.
3) 1G Head, 1G manifold/TB. The ports are bigger, there's more room for air, but as noted above, people have said that it doesn't have the right angle or design. It definitely has more flow potential though, with the larger passages overall.

Also, good on the stroker. Had mine rebuilt, and am only now kicking myself for going the 2L route.. the extra torque and displacement generated will likely be VERY helpful, especially on a GSX.

 

[my98gsx]

thanks for the advice... i called slowboy racing today and they told me NOT to port my head to match the 1G manifold... i also did some research online on the subject. Anyone interested: http://www.roadraceengineering.com/1g2gheadswaptechtip.htm - basicly they said that they have seen: "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."
So that answered my question... im just going to put my ported 2g head and manifold on it and see how it runs.

 

[wvturbo2]

Just put that on now and later save up for smim.

 

[DSMunknown]

Get an Evo III IM. Or click here for some photo references (although, I don't imagine you need them, so it'll be just for those searching the archives).