**sorry for the large pics, I'll fix them with thumbnails later today**
Mods, move this to any subforum you think is best.


I tried this because I'm putting a JRSC originally for a GSR on my LS after I fix the blower.
I just wanted to make sure redrilling an IM flange can work.
The JRSC manifold has enough meat for all head designs (itr/gsr/ls), so that should be easier.

It ended up being very simple, aside from tapping the head's EGR port deep enough for a 3/8" flush plug.
In WI we have heads with the port, but no EGR components. (FYI you need to tap at a slight angle, away from the cam seal.)
The rest was just some mild drilling & grinding on the flange for the different stud locations.

One key part is the intake gasket. The shape of the OEM LS & GSR gaskets don't work with the coolant/egr port differences,
but a Hondata/clone phenolic gasket for a B18B1 makes it work. If you really want to go wild,
you can port-match the wider IM runner to the head.



Here is a cheap P2R gasket for a B18B1 over the modded GSR intake manifold:


Here is the GSR intake manifold's flange with the changes circled in red:


This is the top of the flange, which shows how the top studs clear and the end ear gets cut:


This shows the coolant passage. I used a smaller drill bit, but didn't bother grinding all that material out:


This pic shows the mods needed to clear the middle & upper nuts:



Activation will be best done via a GPO (general purpose output) with eCtune/Hondata/Neptune; I'm not sure if outputs work in Crome Gold.
IIRC "B19Coupe" did this to a built LS and said it had decent low/mid/high gains over a stock LS IM.
This will definately be better (cheaper, more usable power) than a short-runner aftermarket manifold for most street/strip non-vtec builds.
Most people complain aftermarket IM's loose too much low/mid to justify the small top-end gains.

I really don't care how it will perform, since I'll be going with a m62 JRSC not long after.
It's currently colder than a witch's tittie outside, so I probably won't get this fitted onto the motor for a while anyways.

 

I have been wondering why more people didn't do this on B20's. It seems like it would produce a very usable power band. It certainly would be more ideal than a manifold designed for an ITR. Especially on a B20 since the bottom end and the restrictive head flow keep it from revving high enough to use the high rpm flow of the ITR style.

 

I've always wanted to check the feasibility of this but haven't had a P72 manifold laying around for like 15 years. Really wish you had the time to do some tuning with both so we could see the results.

 

I'm in the same boat pulled off my GSR Mani in like 02 for a blox. It's one of the few b-series parts I still have laying around. I'm about to get a jdm b20 tho, and I plan on putting it to use.

 

Manifold Comparison
endyn has a great write up on this from a looooong time ago.
loads more info on his site also

 

The GS-R is yet another configuration. Always enjoyed his writeups though.