Greddy Plenum Spacer Info (Torque/midrange)

[skylineking]

Hi everyone, been searching forums & Google for a while now struggling to find detailed info on my question...

I have an r33 gtst (engine out currently) hks 3037s top mount & many other mods including a genuine greddy plenum. My question is how do I go about gaining the midrange loss back from the plenum? A few posts in various forums said a spacer between the plenum & the head. So this leads me to my questions below

1. How thick should the spacer be?

2. Did it cause any fittment issues?

3. Can you use the same bolts to fit the plenum back on or longer ones to suit?

4. to people who have done this was it really noticeable dyno/road feel?

I'm not here to get plenum choice advice or what somoneones opinion on my setup is or why plazmaman this & greddy that...... just trying to find info on the greddy spacer idea & if it works well.... To anyone who has done this please shed some light on this topic, tell us what car/engine u have & how thick the spacer is + what were your gains.... Thanks in advance

Ps hope everyone had a merry Christmas & have a happy & safe new year!

[Ben C34]

Look at it this way, you have reduced runner length by heaps, a spacer will help a bit but not much compared to stock length, so I wouldnt expect a noticable result at all with a spacer.

[skylineking]

Dammit Ben lol wasn't hoping to hear that haha nah cheers for the post mate I need to hear all the info on this so I can to see wether it's worth doing or not!

Gotta be a few people with RB25's, spacer fitted to their greddy plenum share your opinion/findings please

[Blackkers]

Another potential issue is moving the injectors back by the amount of the spacer. Not sure if it poses problems though.

An option would be to use the bottom half of the stock manifold and use a plazmaman style plenum which bolts up to that.

[Ben C34]

A while ago I had a jeep cherokee for some reason. Moment of madness.

Added a spacer under the throttle body as recommended by the Internet and car went substantially better. Spacer cost me nothing so I didn't care either way.

Inlet manifolds are weird things with all the science going on inside them!

I would give one a shot if cheap enough. I would not worry about moving the injectors back a bit, in some ways moving injectors back is a good thing.

I can help out if you want to get a spacer made. Even though I don't think it would be worthwhile!

Cheers

Ben

Edited December 27, 2014 by Ben C34

[GTSBoy]

I'm with Ben on both of his posts.

Think of the spacer as buying you back a fraction of what you lost.

If it were me, I'd be looking at whether I could turn the last couple of inches of a set of stock runners into a spacer. That way you can retain the injectors in the original location. Then make the cut off ends of the runners into a suitable head equivalent flange for the Greddy manifold.

But before I did any of that I'd look to see if there was enough clearance to the brake master etc.

[skylineking]

Awesome guys keep the posts coming!! Yeah I've been considering the whole injector thing & brake master issues....I was hoping there would be a few guys who have done the mod & can confirm for us! Cheers Ben I'll keep that in mind man appreciate it. Gtsboy that's some good thinking there

[skylineking]

Bump

[skylineking]

Here's another question I'd like to throw out there......... On an RB25neo with a 3076r & plenty of other bolt ons what would give the best mid range torque & spool time out of these 3 forward facing plenum options:

1. Plazmaman plenum

2. Greddy plenum with a spacer

3. RB26 plenum with itb's

& I'm not talking about throttle response I'm talking about best mid range/less lag plenum! Interested in people's thoughts cause they are my 3 options from here on in. People who have done any of these setups please share your thoughts & to any lucky (or should I say unlucky person) that has done a couple of different setups in the quest of best mid range ff plenum please share your pain & gain

[Ben C34]

I'm going to vote for plazmaman. Having never tried any but based on how much effort manufacturers go to to get long runners. Even on large v8s long runners very time. Factory cars want torque, long runners win.

[GTSBoy]

I'd agree with Ben on the same principles. I'd also suggest that the differences between Plazmaman and the spaced Greddy might be too small to feel

[skylineking]

That's what my thoughts were until I was reading about the 26 itb plenum & when blitz did it to nomuken's car they gained power accross the whole rev range..... Just not sure if it's all true cause plazmaman guarantee their results & some people didn't get good results using that plenum so I'm worried same thing will happen with 26 plenum

Here's the link by the way to the blitz info hard to read in jap lol

http://www.ricohracing.com/ricoh-home/ricoh-home/rb25henkan/rb25_6ren.htm

Ps I can buy an adapter decently cheap to be able to put the 26 plenum on so price isn't the issue its just what will work best?

[skylineking]

Gtsboy that's what I was hoping to hear but it seems like the people who have spacers on their greddy's are no where to be found or just don't wanna tell us lol

Any dyno results would end all the head scratching hahaha

[Dan_J]

A while ago I had a jeep cherokee for some reason. Moment of madness.

Added a spacer under the throttle body as recommended by the Internet and car went substantially better. Spacer cost me nothing so I didn't care either way.

Inlet manifolds are weird things with all the science going on inside them!

I would give one a shot if cheap enough. I would not worry about moving the injectors back a bit, in some ways moving injectors back is a good thing.

I can help out if you want to get a spacer made. Even though I don't think it would be worthwhile!

Cheers

Ben

hey ben,

was that a plastic type spacer that would also shield the heat soak off the head or was it alloy ?

[Ben C34]

hey ben,

was that a plastic type spacer that would also shield the heat soak off the head or was it alloy ?

Alloy, and between the throttle and manifold so no heat soak benefits.

[BlackBox]

http://www.maceengineering.com.au/epages/shop.mobile/en_AU/?ObjectID=1469391&ViewAction=ViewProduct

[GTRPSI]

In a nut shell.....generally speaking.....

The rule is longer ports are better for bottom end range, shorter ports for top end range.

The opposite goes for runner diameter, smaller dia runners for bottom end, larger dia runners for top end.

So something for pulling down low would have long narrow runners, a screaming high rpm big power engine build would have short large diameter runners.

[skylineking]

Blackbox & GTRPSI thanks for the inputs.

By the sounds of it the plazmaman plenum seems to win in this situation now to find one for a neo at a good price ?

ps anyone with more info please throw your 2c in here

[wildeagle44]

I just had a look at mine, space isnt an issue. It could be worth a try.

Back in my commodore days a few people spaced there inlet mani to pick up some torque.

[skylineking]

Thanks wildeagle44, how many mm's do you think the spacer could be before you would have space/fittment issues?