Options For New Inlet Manifold - 100mm, Retain Itbs

[dorifticon]

Hi everybody

Looking to upgrade the inlet manifold on my rb30dett and just wanting to know if there's any options beyond hypertune out there that might fit my requirements. Specifically:

1) I definitely will be retaining the 6 x ITBs.

2) I want to run a 100mm/4" inlet diameter, in anticipation of going to a full 4" intercooler and turbo outlet system once I convert to a single turbo.

The last time I looked into this hypertune seemed to be the only item that could meet these requirements but I thought that since then something else might have entered the market. I basically want a nice big plenum with a quality, machined face to bolt on, seals properly, that flows nicely and distributes flow to the rear cylinder. The hypertune price range would be the upper end of what I'm hoping to pay and if anyone can recommend a good Australian distributor that I can chat to that would be great.

Also, are there any issues I might have particularly with a deck height that is now +38mm, eg: clearance with clutch mcs etc - I'm already assuming I may need to go to an r33 style clutch mc. I am currently running the factory fuel rail with 1000cc injectors but all the ones I've seen have factory mounts for the rail as well. But any other tips on clearances and fitment etc would be greatly appreciated. Thanks in advance.

[scotty nm35]

4 inch intercooler pipes? Man... What's wrong with the 80mm?

[dorifticon]

  On 27/05/2015 at 2:50 AM, scotty nm35 said:

4 inch intercooler pipes? Man... What's wrong with the 80mm?

Am currently running 22-23psi on a set of HKS 2530s. It has a built rb30 bottom end and big cams, so when I go to a single turbo (around t88 size or so) I will be upping the boost considerably.

EDIT: this is not intended to be a street/daily driver car.

Edited May 27, 2015 by dorifticon

[scotty nm35]

The more boost you run the smaller the piping needs to be. Unless you are chasing over 600kw I would leave the stock piping in place.

[jangles]

Also, at what power level do ITB's become a hinderance over single?

CPC, custom plenum creations do plenums. So do RIPS in NZ. Both would make what you want.

Or modify the stock plenum, don't quote me, but RACEPACE did/do that?

[Piggaz]

  On 27/05/2015 at 5:02 AM, jangles said:

Or modify the stock plenum, don't quote me, but RACEPACE did/do that?

I believe it was lengthening the runners for more midrange twist.... IIRC.

[sneakey pete]

Greddy is 100mm inlet, not a flange face though.

[bigmikespec]

  On 27/05/2015 at 5:02 AM, jangles said:

Also, at what power level do ITB's become a hinderance over single?

CPC, custom plenum creations do plenums. So do RIPS in NZ. Both would make what you want.

Or modify the stock plenum, don't quote me, but RACEPACE did/do that?

The ITB's will always disturb the airflow and create a pressure drop across the port compared to a single TB manifold.

If you just want to make big power and less pressure drop through the system putting a single TB on the stock plenum is the cheapest way out.

If you are serious, a much larger volume plenum (which helps with distribution of flow) with a 100mm TB like you want is probably better and big piping, no flow restriction!

[dorifticon]

  On 27/05/2015 at 3:15 AM, scotty nm35 said:

The more boost you run the smaller the piping needs to be. Unless you are chasing over 600kw I would leave the stock piping in place.

Currently on 385kw or so (at the treads) but turbos are way undersized for my application. Would ultimately like to get into the 600's once fuel system (including switch to ethanol) is sorted.

  On 28/05/2015 at 12:32 AM, bigmikespec said:

The ITB's will always disturb the airflow and create a pressure drop across the port compared to a single TB manifold.

If you just want to make big power and less pressure drop through the system putting a single TB on the stock plenum is the cheapest way out.

I don't want to lose the off-throttle response or the effect of the brake booster on sudden switch from throttle to brake. It's one of the things I like most about the rb. I realise it makes tuning a PITA and may limit power, but have driven a single throttle and it's not for me.

Thanks for all the names/etc so far, will continue the research.

[jangles]

Just saying it was a single throttle and no good doesn't really explain the whole picture.

The setup might of been crap, single or itb.

[bigmikespec]

  On 28/05/2015 at 4:09 AM, dorifticon said:

Currently on 385kw or so (at the treads) but turbos are way undersized for my application. Would ultimately like to get into the 600's once fuel system (including switch to ethanol) is sorted.

I don't want to lose the off-throttle response or the effect of the brake booster on sudden switch from throttle to brake. It's one of the things I like most about the rb. I realise it makes tuning a PITA and may limit power, but have driven a single throttle and it's not for me.

Thanks for all the names/etc so far, will continue the research.

That quote about smaller piping wasn't right, I am not sure what Scotty meant?

In any case, you can upgrade the piping but the biggest restriction will probably be the ITB's, in which case, the money spent upgrading pipe work is best done elsewhere. Unless you do change it anyway to go to a big single turbo then by all means upgrade to larger piping, but you will most likely on get a small gain in flow (less pressure drop) through piping.

[iruvyouskyrine]

A photo Birrong Automotive put up of one of their customers cars. Might be worth investigating.

[scotty nm35]

  On 28/05/2015 at 6:16 AM, bigmikespec said:

That quote about smaller piping wasn't right, I am not sure what Scotty meant?

Have seen 500kw through the stock piping, now he is going for 600kw. I will let you know how he goes.

After seeing 350kw through 2.25 inch piping, 80mm should therefore easily flow 600 by my books. Just letting you know as most workshops would have upgraded it at much less power. The more you compress the air the smaller the pipes need to be, that much is obvious yeh?

[Leroy Peterson]

perhaps the word boost should be replaced with air volume in this topic? since there are so many things changing in this setup (turbo, intake manifold, intake piping, power output) throwing around estimations and requirements for boost levels is pretty irrelevant.

no one is doubting 2.25 inch piping wont flow big numbers, i think the question should be 'is 4" piping worth it?' smaller piping flows less (or requires more boost) and dissipates less heat. probably not worth the effort to fit 4" though especially if it limits your plenum choices.

[r32-25t]

If the turbo outlet is only 2.5in why would the rest of it need to be 4in?

[GTSBoy]

  On 29/05/2015 at 12:44 AM, r32-25t said:

If the turbo outlet is only 2.5in why would the rest of it need to be 4in?

The turbo outlet is only 2.5" because the size of the compressor housing is such (diameter, thickness) that you couldn't easily make the outlet bigger. On top of that, centrifugal compressors basically work by turning air velocity into static pressure. The velocity in the compressor housing is very high, and you want that to slow down as gradually as possible (hence the shape of the volute of the housing). If you tried to take that same compressor housing out to, say, a 3" outlet, then you'd either have to be less gradual or make it a lot bigger (longer in the outlet). This would make for poor performance on the one hand and poor packaging on the other. I think we should ignore for the moment the fact that most such turbos then get installed with a nasty elbow directly off the outlet.

But the velocity in the 2.5" outlet is probably too high for good pressure drop characteristics if you were to keep the pipework at 2.5", so it make sense to go up to 3" or whatever is needed to get the air velocity back into a more reasonable range. And of course people will argue about what a sensible velocity range is and they will argue about what power level = what boost = what airflow without paying any attention to the type or size of engine or turbo. But we'd best ignore that too!

[dorifticon]

  On 28/05/2015 at 11:21 PM, Leroy Peterson said:

no one is doubting 2.25 inch piping wont flow big numbers, i think the question should be 'is 4" piping worth it?' smaller piping flows less (or requires more boost) and dissipates less heat. probably not worth the effort to fit 4" though especially if it limits your plenum choices.

the piping setup in my 'R needs to be changed anyway, when I got the extra 38mm deck height from the rb30, I did a "temporary" hack and clamp job to extend the OEM rubber pipes and was never super happy with it. So this incremental cost of upgrading the piping (especially in light of everything else) should be not much. There's going to be a lot of pipe cutting and welding in any case for the single turbine setup.

In terms of whether it will be better or worse than the 80mm setup, I figure the stock power on a GTR was in the 200's, so upgrading the cross-sectional flow area by around 60% shouldn't be a bad thing if chasing power levels that are well over double the stock output.

[scotty nm35]

Power should be slightly better if there aren't extra/tighter bends in it, and transient response will be slightly worse I imagine. Bang for buck it may be a waste, but that's for you to decide. Depends what you plan to use the car for.

Just remember stock boost is only one bar too, you will be running twice that most likely, so the pipes should flow around 50% more air from that alone, and the factory pipes were overkill for stock power.

[bigmikespec]

  On 28/05/2015 at 10:49 PM, scotty nm35 said:

Have seen 500kw through the stock piping, now he is going for 600kw. I will let you know how he goes.

After seeing 350kw through 2.25 inch piping, 80mm should therefore easily flow 600 by my books. Just letting you know as most workshops would have upgraded it at much less power. The more you compress the air the smaller the pipes need to be, that much is obvious yeh?

It will work, but it won't be efficient. Pressure drop through the pipe work alone might be 10psi at a random guess at high flows.

Assuming constant flow, the smaller the pipe will produce an increase in pressure.

[scotty nm35]

  On 29/05/2015 at 1:15 AM, bigmikespec said:

It will work, but it won't be efficient.

True...

Op should run 6 inch piping for efficiency.