EFI plenums for L28

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I realised a while ago that I am running the wrong plenum on my L28. It is from an L24E I think. Anyway I have checked and I have three spares but they are all different models (although almost identical looking).

 

P71, P88, P72

 

I am going to have a head modified and the ports matched. I am also going to have the plenum excruded. But I want to know how to choose between the three?

 

Should I just fill them with water and the one with the biggest volume wins? Or should I go with the P88 because it is likely to be the latest design encorporating minor improvements?

 

I also thought about slicing two in half welding in some trumpets on each runner and then putting the plenum over the top but it doesn't look like it would work.

 

Any suggestions?

[NZeder]

I think you will find that all suck really Nissan build the EFI setup on the L28 for emission first, economy second and performance last much like most EFI setups on cars these days. They will not flow enough to get an L28 past 6300rpm (ok they can rev past that, but it is hard work and peek power has long gone at 5800 rpm from these plenums)

 

I believe the NAPS items have more volume and a twin butterfly setup that help with good compromised plenum (they have NAPS Computer cast on the top)

 

See if you can find a P65 plenum they are very different see this tread I started on Hybridz year back

http://forums.hybridz.org/index.php?/topic/39280-p65-efi-intake-manifold/page__hl__efi%20plenum

[PZG302]

Greg,

 

Your post on EFI plenums a while ago covered them. The best manifold yopu can get would be a N47 cast manifold, I believe from the L28ET. The runners are about 1/2 inch longer than the standard L28 manifolds and it has a 63-64mm throttle body standard.

 

The twin butterfly throttles are crap and too restrictive. The NAPS manifolds aren't much chop because of the twin butterly design.

 

Here's the link to you other post.

 

 

http://www.viczcar.com/forum/index.php/topic,4222.0.html

 

Another easy mod to get a decent size throttle body is to use an XF falcon one, diameter of 65mm and a relatively easy mod to do.

 

When you say you are getting the ports done, what work exactly and what are you hoping to achieve from this. My N42 head has had some portwork done, but only cleaning up the ports not opening them up at all because I want to produce torque, which makes the car a lot more driveable for the track.

 

Who are you using to do the engine work? From who I know up here in Brisbane I would recommend Jim Milliner as he is doing my motor the way I want it built to produce the power and torque in the way I want it delivered.

[NZeder]

There is a BMW 65mm TB that you can use the N47 manifold too - almost a direct bolt on too (2 of the holes in BMW TB need to be made oval) - just need to port the TB opening to match. That is what I had when I had one of these manifolds when I was thinking L28ET a few years back.

[dat2kman]

Greg, add in there a P76 manifold, this is the twin butterfly ( one of them) I have had  most of these run up on an airflow bench looking for problems ( found plenty) and then had them modified ( to reduce/eliminate problems)

the only way to do it properly is to slice the manifold horizontally, then work on each runner and the inside of the log, them weld it all back up.

Rules for my class racing say "internal is free, external must remain same dimension."

I have charts listing the befores and afters of the airflow bench testing, I used Jim M's drag racing guy, he does the flow work for the 888 V8 team!

Not cheap either Greenup was going down this path but wasn't too keen on the cost, 'sides he is just ramming air in, and his thing is totally different!

 

I could sell you my p72 "after" manifold, to save a lot of hassle, lets talk!

 

The N47  (pzg302) would seem to be the best of the lot, as a basis start, it then needs a lot of deep internal work, that even a longneck die grindar cannot get to. I would like to get one for myself to go to work on.

Anyone got one lying around??? ( N47 inlet manifold that is)

[kolonelklink]

+1 for NAPS... Have an adaptor made for a 60mm TB and get the runners portmatched as deeply as possible. NAPS do no have the EGR bump at the runner mouth(which is a good thing!)

Anecdotally it's worked very well for me in the past with programable EFI.

 

-Pete

[Zedman240®]

If you are after a NAPS manifold, have one here if you need it. And some throttle bodies. One from a RB25DE, and twin butterfly ones.