Is it possible to fit the quad throttle body manifold on an NA head if you combined the manifolds so the ports matched up?(i.e. weld and fabricate the runners to match)I've never seen the gti-r manifold so I don't know the differences.

Originally posted by scmser
Is it possible to fit the quad throttle body manifold on an NA head if you combined the manifolds so the ports matched up?(i.e. weld and fabricate the runners to match)I've never seen the gti-r manifold so I don't know the differences.

The GTi-R manifold will not fit.

What you propose to modify it may or may not work, but you'd be better off making a short runner manifold from an NA manifold. All the quads will get you is a little extra throttle response.

yes it will fit, the only difference is that the ports are slightly larger and the bolt pattern is sligtly different and you must use top feed injectors. You gotta have a machine shop drill new holes but essentially, the ports have the same spacing and shape. You also have to match port the head or get a port and polish. For the injectors, you can use top feed's from a 89 240SX KA24E motor, same 260cc rating. And pardon me GEO, its not a slight increase in flow and response, more like a MAJOR increase in flow and throttle response. In fact individual throttle bodys are known for almost instantanious response, thats why they are so damn hard to tune.

Originally posted by shoe
yes it will fit, the only difference is that the ports are slightly larger and the bolt pattern is sligtly different...

The port shape is completely different. The NA and BB ports have a "cut" in the top of the port while the GTi-R port has a "cut" in the bottom. I'm 99% sure this is due to the injector placement. You would have to weld up part of the NA head and reshape the ports.

Originally posted by shoe
And pardon me GEO, its not a slight increase in flow and response, more like a MAJOR increase in flow and throttle response. In fact individual throttle bodys are known for almost instantanious response, thats why they are so damn hard to tune.

The reason the GTi-R manifold will make more power is the short runners and large plenum. You can get that much easier by modifying a NA manifold. These are already available as a bolt-on if you don't want to modify one yourself (or can't). Pricewise it's pretty similar between a short runner NA manifold and a GTi-R manifold. At the time I built my killer NA engine I had the opportunity to buy a complete GTi-R manifold and passed because of the port problem. The Rob Williams short runner manifold was not available yet.

The quad TBs will only hurt flow, not help it, except at partial throttle openning. In the end the TBs will increase throttle response because for the same amount of movement on the gas pedal, you get a larger total throttle openning.

Originally posted by Geo91SER
The quad TBs will only hurt flow, not help it, except at partial throttle openning. In the end the TBs will increase throttle response because for the same amount of movement on the gas pedal, you get a larger total throttle openning.
Geo,

are you referring to the GTiR quad TBs or quad TBs in general in the above statement?

Chris

the ports are not completely different and the cuts are not for the injectors, its for vacuum lines. ill try to get a digital camera to show you.

the ports on the GTI-R manifold are slighly larger, so if you have this on a stock motor, you would defniately lose port velocity

I was just inquiring. I have no plans to try this. Thanks for the responses.

Originally posted by shoe
the ports are not completely different and the cuts are not for the injectors, its for vacuum lines. ill try to get a digital camera to show you.

I don't need your photos. I have my own thanks.

I see what you are saying about the vacuum lines. Strange that there is a cut-out all the way to the port. Any idea why?

As for the ports, the shapes are different. The top of the port on the DE head does have a cut-out for the injector spray. You would have to weld up the ports in the NA head and fill that in. OK, you could be a monkey and ignore it, but that would screw with a lot of things in a critical area of the air flow.

I stick with what I said except the cut in the bottom of the GTi-R port is not for the injector.

http://home.earthlink.net/~geo3/GTi-R1.jpg

http://home.earthlink.net/~geo3/GTi-R2.jpg

http://home.earthlink.net/~geo3/PHOTO020.JPG

yeah the vacuum cut out is on the bottom of the GTI-R manifold, and the cutout for the injector is on the top of the SE-R head. However, when u port match the head, the cutout will be smaller. when i had the machine shop drill holes on my intake, i gave him perfect instructions and being the dumbass he is... he drilled them with the gasket the wrong way. i told him that the flat side of the gasket covers the cutout but i guess he wasnt listening. so now i got 2 sets of holes i dont need. weight reduction?? haha

Originally posted by hpro123

Geo,

are you referring to the GTiR quad TBs or quad TBs in general in the above statement?

Chris

Any quads.

They will give you throttle response, but unless your stock TB is the choke point of the system (ours is not), you won't gain power from a larger TB (part of the effect of the quads).

The other effect of the quads IIRC is to create a bit more vacuum behind the throttle plates. This will also help with throttle response when you crack open the plates.

Originally posted by shoe
yeah the vacuum cut out is on the bottom of the GTI-R manifold, and the cutout for the injector is on the top of the SE-R head. However, when u port match the head, the cutout will be smaller.

Perhaps it would be best to create a matching cut in teh manifold as well if you are not welding up the ports in the head. I don't know however. Porting is as much art as science and I couldn't comment there. I don't think I'd want that step created by mismatched ports however. That would create a pretty fair amount of turbulence as what I think would be a critical place in the intake tract.

I'll go back to what I said originally.....

I think a better solution would be a modified NA intake manifold such as the one Rob Williams sells.

im sure any machine shop with a TIG welder can solve that problem.