Inlet Manifolds

[neofenrir34]

Ok now i have seen that this has been covered in a few threads before but the most recent one i could find was late last year. So here is what i Have, 1998 R34 GT-t with a RB25DET Neo motor

What i am after, A forward facing Inlet manifold in similar styling to a GT-R version. Reason being that i refuse to run the intercooler piping back across the engine into the standard inlet plenum. (FYI every 90 degree bend is worth at least 1.3m of piping and a pressure drop of about .5psi on average. if you have seen the garret calculation that works out to be a fair bit of power over all) I am not so worried about the flow rates of the manifold/runners as long as it is as good as the stock one (if not better)

OK so i have heard of a lot of people cutting the runners and just welding on a GT-R plenum, i am trying to steer clear of that option if i can.I also know someone that can fabricate a complete manifold if i want so that is also a option. but i would prefer it to be a more straight forward thing if i can.

I have Seen on Ebay a inlet from PnT performance in the style that i am after.

http://cgi.ebay.com.au/R34-skyline-RB25DET...=item27b2ae94d6

The questions i have are.

1. Has anyone used one of these?

2. If so has there been any fitting dramas at all. like having to alter where the battery sits? (i don't mind having to re-route hoses or wiring)

3. has there been any failure's? what was the cause?

if i have missed anything that you wanna know (like my plans for the car or exactly what i am chasing) please let me know.

Edited October 19, 2010 by neofenrir34

[KiwiRS4T]

RIPS will make you one but it will cost more than the ebay one.

[Adriano]

How much power are you after. By your calculations simply fitting a forward facing plenum to a stock car will give you more power, which is far from the case. The shorter runnurs of the forward plenum reduce low and midrange torque

[R31Nismoid]

By your calculations simply fitting a forward facing plenum to a stock car will give you more power, which is far from the case.

Exactly

And each 90 degree is hardly worth .5 of a PSI. By that most cars would be dropping what, 2-3psi?

Go and test it, the drop 9 outta 10 times (from turbo to throttle body) is caused by cheap cooler cores... Not the bends.

Issue with the NEO, there aren't a lot of options.

The best obviously is get a plate made and use a GTR item.

[r33_racer]

I was under the impression every 90 was worth about 1psi. Only way to tell for sure is to monitor pressure at turbo outlet and then at the manifold to see overall drop and work it out from there.

[juggernaut1]

IMO in order to gain a benefit out of these short runner intake manifolds you will need to spin more rpm.

Generalising.....if you are going to drive it in the stock rpm band then stick to the stock manifold for the best overall power/torque curve.

[Legionnaire]

I have Greddy plenum fitted on my DET Neo, the one intended for R33 engine. I don't have pre-installation dyno graph, but subjectively speaking it felt less torquey at low revs up to maybe 2500 or so. I'm not sure about this 0.5psi loss per 90 turn, I guess it depends on pipe diameter, mass flow rate, flow speed, etc.

Edited October 19, 2010 by Legionnaire

[Jezza-gtR]

I just finished installing a GReddy front facing plenum on a stock RB25DET. Driving the car before and after I didn't notice much loss down low but up high got a huge gain. Will be interesting to know how the car will be once tuned. All this in an S13. I'll post some pics tonight.

[neofenrir34]

Exactly

And each 90 degree is hardly worth .5 of a PSI. By that most cars would be dropping what, 2-3psi?

Go and test it, the drop 9 outta 10 times (from turbo to throttle body) is caused by cheap cooler cores... Not the bends.

Issue with the NEO, there aren't a lot of options.

The best obviously is get a plate made and use a GTR item.

I never said anything about gaining more power just by putting a forward facing inlet. My main point is gaining over all throttle response (and please don't start talking about dyno charts and torque curves, they tell nothing about the efficiency of the intake and turbo systems, only power levels unless you have full data logging and do a variety of tests)

You would be surprised about how much pressure is lost from the turbo to the inlet (2psi quite a normal loss, is some cases 4psi is not unheard of). The bends reduce response of the engine and at higher boost levels cause bigger problems.

I am not so worried about torque levels a low rpm, in most cases with correct tuning and supporting mods this can be adjusted to minimize losses in that area. I am well aware of the effects of inlet runner lengths (venturi effects) and how these things effect the engine power and torque curves

My main question is has any one fitted One of these PnT performance "JUN" style ebay inlet manifolds and had success?

That is what i am asking.

[neofenrir34]

I was under the impression every 90 was worth about 1psi. Only way to tell for sure is to monitor pressure at turbo outlet and then at the manifold to see overall drop and work it out from there.

Well it can vary depending on the system but .5 is conservative average.

[neofenrir34]

I just finished installing a GReddy front facing plenum on a stock RB25DET. Driving the car before and after I didn't notice much loss down low but up high got a huge gain. Will be interesting to know how the car will be once tuned. All this in an S13. I'll post some pics tonight.

thanks i would be interested to know how this works out after a good tune

[R31Nismoid]

Well it can vary depending on the system but .5 is conservative average.

Based on what testing?

We are telling you its not that much. I've not seen that on my own car with a factory return style intake.

I never said anything about gaining more power just by putting a forward facing inlet.

well by losing "0.5psi" you are actually losing power, as its a restriction.

So you did... You also then went on to say:

if you have seen the garret calculation that works out to be a fair bit of power over all)

So whether you "were" or not, fact is you did and hence we are all pulling you up on it.

[wolverine]

Or then there is the half way answer

[Jezza-gtR]

Said pics:

[neofenrir34]

Based on what testing?

We are telling you its not that much. I've not seen that on my own car with a factory return style intake.

well by losing "0.5psi" you are actually losing power, as its a restriction.

So you did... You also then went on to say:

So whether you "were" or not, fact is you did and hence we are all pulling you up on it.

OK yeah i can see how it reads like that, i am sorry for that. It is not how i meant it to read.

My statement about Garrets calculations was in regards to it being possible power that could be gained, at the levels i am talking about it isn't really practical even worrying about.

The gains i am chasing are more on the side of increased efficiency within the entire turbo and intake system resulting in increase response, it is not like i am chasing that small amount of extra psi, after all that 1psi extra is more then a acceptable loss

All systems have restrictions and it is true that the main cause is the cooler core itself but it can also result from piping.

Again i apologize for the ill worded posts

Although i do believe we have been caught up in a off topic discussion.

[75coupe]

I have a RIPS plenum and have been told the plenum chamber near cylinder 6 is rather small as it tapers quite a bit, best plenum from what Ive been told by a few people now is the hypertune one...

[neofenrir34]

I have a RIPS plenum and have been told the plenum chamber near cylinder 6 is rather small as it tapers quite a bit, best plenum from what Ive been told by a few people now is the hypertune one...

Yes hypertune have awesome inlet manifolds the R&D put into them is unbelievable. they can custom make one with no problems there, but the cost would be most likely be more then i am looking to spend, plus they like to have the car to do it. It is a shame really.

[75coupe]

I dont think the intake plenum is a thing you really want to skimp out on...

spend the money on a good one straight up, it will just be a hassle or tuning issue otherwise...

[PM-R33]

What turbo is running on the motor? What is the rest of the setup?

[neofenrir34]

I dont think the intake plenum is a thing you really want to skimp out on...

spend the money on a good one straight up, it will just be a hassle or tuning issue otherwise...

i have been thinking about it that way also. That is one of the reasons for topic