MD Manifold Spacer to Increase Runner Length?

E

EG3

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Well I was reading about the DIY Plenum porting thread on my350z.com and came onto the runner length and adjusting it. It looks like our engine might get some low end torque if the runners were a little longer but obviously we don't have space in the lower plenum for that. How about using the Manifold spacer for that?
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Obviously, this is used to allow taller injectors in FI applications but wouldn't it also increase the runner length without any adjustments to the runners at all? The Z and G NA users don't have enough clearance under their hood after the spacers and etc but we have plenty.. Worth trying it out? What do you think?
 
Z1Performance said:
it won't amount to squat TBH
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Why not? I agree that a single one won't do anything significant but how about you use 2 of them to increase length by an inch? Plus, I'm not talking about increases you'd get from FI or cams. I'd be happy if it'd add 5-8 more hp and 5-8 more tq..
 
Use 2 of them to increase it by an inch and then let me know how you plan to fit your fuel injectors back in the car :) You can't even use one of them and have the stock injectors/rail fit correctly.

You're not going to net anything meaningful, or IMHO, even measurable, by using a spacer here. That part of the manifold isn't where the problem is. The primary flaw in the manifold is the entry point. However, that's not something easily or inexpensively solved. So they (ie the aftermarket) go to the next "problem" area - the overall air volume cylinder to cylinder. This is where the plenum spacer comes in. It's an inexpensive mod that is easy to install and does a good job of addressing an area that is in actual need of improvement. Gets a more equal volume of air going to each cylinder and as such, gives a reasonable increase in hp and torque.

Trust me on this - my car has one of the highest NA outputs out there, and our machinist spent well over 100 hours with the flow bench and manometer invested in my intake plenum/heads alone (and in doing so, I paid a small fortune just to find out what is and is not worth doing) - I know of what I speak ;) Unfortunately, this just isn't an engine that offers alot of free lunch - the power can definitely be made (and in abundance) but it does take pretty big investments of time and capital
 
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?Thanks for the enlightenment Adam :tup: Btw, did you play with the runner inlet angles in the lower plenum? There was a thought somewhere to angle them backwards (ie, more than 90 degrees as it is now). I have a spare upper and lower plenum so plan to try something out later this month.
 
This is from the DIY Plenum porting thread on my350z. I don't plan on doing the full polishing stuff, I don't believe it. I'll probably just cut off a little from the top part of the inlets but got curious on this. The original user didn't do it I believe, just wondering if you've had tried it:

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couldnt tell you - well beyond my level of expertise. Personally I would not touch any part of the plenum or manifold without the use of a flow bench or manometer - otherwise you're just guessing and you cant reverse your steps unfortunately. I left this stuff up to my machinist to handle
 
I'd be nice to put the fluid mechanics classes to use but anyhow, thanks for the info Adam.. I'll be in NY two weeks from today and maybe get that GTSpec mid chasis brace from you. I'd be nice to meet if you're around..

Ege
 
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