Installing Nismo plenum on an R33 GTR without dropping the engine?

[joshuaho96]

Anyone ever done this? Nismo says the plenum doesn't fit without dropping the engine first, I've heard from people that it can fit without doing this but it sounds like it might be a real challenge. Obviously this is a really expensive pointless mod for power but supposedly it helps a bit with turbo lag with the longer runners and better cylinder airflow distribution so cylinder 6 and the rear turbo is less likely to fail first. OEM plenum/collector came out pretty easily, the intake manifold was the really challenging part.

[Piggaz]

Can be done, done it myself. You need to take off 5 and 6 throttles and studs. When putting it back on you’ll need to line the intake plenum and throttles with the gaskets and screw the studs in.

Enjoy. 🤣

[joshuaho96]

On 9/8/2021 at 4:58 PM, Piggaz said:

Can be done, done it myself. You need to take off 5 and 6 throttles and studs. When putting it back on you’ll need to line the intake plenum and throttles with the gaskets and screw the studs in.

Enjoy. 🤣

Guess I'm going to have to buy a bunch of thin nuts, from what I recall when I pulled the plenum off it barely cleared the clutch master cylinder. Someone else suggested pulling the clutch master cylinder to get enough clearance but that makes me nervous with the hard line coming off of it. Is it really just cylinder 5 and 6 that need the studs removed? I'm trying to picture it mentally and the only way I can imagine that working is if you cant it in somehow.

Also, any idea on torque spec for those studs? Hand tight?

Edited September 9, 2021 by joshuaho96

[Piggaz]

Pretty sure that was it. It was 12 years ago. The factory one is a snack to get on and off by comparison.

You won’t be able to slide it on with 5 and 6 studs in place. They MUST be removed.

[joshuaho96]

On 9/9/2021 at 1:21 AM, Piggaz said:

Pretty sure that was it. It was 12 years ago. The factory one is a snack to get on and off by comparison.

You won’t be able to slide it on with 5 and 6 studs in place. They MUST be removed.

So there's actually a few additional notes here, one is that the cylinder 3 and 4 dowel pins must be on the ITBs, not the plenum/collector. Otherwise there is literally not enough clearance. I am amazed I got it on without some kind of catastrophic damage to the mating surfaces. I managed to get all of cylinder 5 studs back in after putting the collector on, then the top stud for cylinder 6. I had to use the double nut method, for some reason my studs after zinc coating require a wrench or something to help them tighten down. It definitely feels wrong, I have to carefully (emphasis on carefully) tighten it down until I feel the stud bottom out, then back it out ever so slightly so a stress riser is not created before trying very hard to not adjust the stud depth while removing the double nut locked together.

The problem with cylinder 6 is that there is so little clearance I literally cannot get a crescent wrench or crows foot wrench to hold the back nut still while I tighten/loosen the front nut with a 12mm u-joint socket, so the stud is not properly seated. Any ideas?

[joshuaho96]

I managed to do it. I highly recommend a 60 degree open-ended wrench/spanner for this job in conjunction with a 12mm u-joint quarter inch socket for the rearmost stud at the bottom of cylinder 6. Also as I mentioned make sure you put the dowels on the ITBs, not the plenum/collector, otherwise you won't clear the studs. It will barely clear and maybe scratch the gasket face a little around the bolt hole areas.

[joshuaho96]

Additional note: The brake + clutch vacuum booster pipes are an absolute pain in the neck to get in compared to the OEM lines. You must use the Nismo-provided pipes to clear everything properly. I would recommend maneuvering the pipe to stick out between cylinder 5 and 6 as it should before you put the collector on the intake manifold/ITBs. You can do it afterwards like I did but expect to do a lot of maneuvering to figure out how to make it happen, you should expect to have the fuel filter unbolted as well as the boost solenoid and fuel injector resistor pack taken off to make more room. Getting the gasket in place is an absolute pain in the neck when the coolant pipe mounting tab is actively pushing this pipe out of place.

Also, Nismo includes a replacement part for the oil pressure sensor bracket that connects it to the vacuum/coolant pipe that is directly above it. I assume you need to put this bracket on to get everything to fit correctly, presumably the spacing is slightly different relative to the OEM plenum which will cause this coolant pipe to not fit up correctly with the air chamber under the plenum. Do this before the plenum goes on instead of after, it is much more annoying/difficult to do it when the manifold + collector is blocking access.

10mm u-joint and 12mm u-joint quarter inch sockets as mentioned are mandatory for this job. I cannot imagine how you would even attempt to do things like bolting up the brake/clutch booster pipe without one. Even though a wrench will get on the bolt, I only have like a quarter turn before I'm hitting something and a ratcheting wrench will be too big to clear the pipe.

[joshuaho96]

Yet another bump. I recommend buying new hoses for your brake and clutch master booster because my brake booster hose is rock hard and split at one end. I'm going to live with it for now but the replacement has been ordered. The plenum intrudes and takes every little bit of space that the factory clutch booster setup needs so the Nismo manual for this part details how you need to remove the clamp that goes around the check valve as well as the bracket that holds the hose and check valve straight. You will still need the nut and lock washer that goes to the clutch master cylinder, just the bracket is removed. The rubber insulator on the check valve clamp is also retained on the check valve as far as I can tell, presumably to try and keep it from grinding into the plenum.

This thing has been a ton of work and money, so hopefully the long runners at least do something for low RPM response. It's definitely not going to be a huge difference but just looking at a similar kind of experiment I'm optimistic: 

 

[sin-]

Nice work and updates.

[niZmO_Man]

C'mon mate, go variable intake length! (I'm kidding)