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Matching Plenum To A Built Motor With 2530's Running Flex Fuel 98 / E85


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Hi Guys,

I've searched everywhere for some clear answers and to be honest I haven't found anything that is really relevant to what I've already got and am about to do. I've tried to include a list of everything below to take out any questions around the hazy pending supporting mods line I keep reading.

This might be an old topic for some but for my combination I really think I'm on the fringe here and could go either way in terms of which plenum is going to give me the best results. And what I mean by that isn't all about max HP but for best all round performance... mid to high range is def important and sacrificing a little down low isn't totally out of the question if the mid to high benifits are worth it. I should also say that the car is for street use only. (Hence the big single option wasn't one incase you're wondering why).

To this point I'm trying to make a call on the big dollars of the Nismo plenum VS the Greddy (genuine).. the Plazmaman is just too expensive but if that was cheaper I would consider it if it were a better choice than the first two I mentioned.

The motor is practically new with everything being built with around 8000km on it.

N1 block 20 though over nitto forged pistons

i beam rods

nitto metal gaskets

tomei oil restrictor

high octane sheet metal sump extension

Tomei sump baffle

stock crank

nitto oil pump

the head is from an R34 with a mild port and polish, stock lifters and valves.

Tomei Type B cams with cam baffles & hks cam gears.

ATI 1000HP h-balancer

I have a HKS R Type 103mm front mount with hard pipe kit and the HKS racing twin pipes & filters.

stock radiator.

HKS dump pipes

Apexi front pipe

Kakimoto Full Mega N1 exhaust - silencer removed (90mm)

------------------------------------

What is on order from Japan and the States

HKS 2530's with HD HKS actuators (under 5000km use and in excellent condition).

Tomei Expreme Manifolds

ID2000 injectors

------------------------------------

I'm running a Haltech Platinum Pro and I already have the I/O expander with the Haltech ethanol sensor module.

This will all be getting fitted and setup for E85 on a flex fuel system.

I also got an AEM wifi wideband and EGT (twin sensors) which I plan on running into the Haltech to get further benefits in tuning and to better understand what the cars doing and how's it's operating when under load.

I'm also going to be looking into ceramic coating the turbo housings and manifolds if the price is justified for the benefits and using a heat shield around the turbos if there's enough room to do so. I'm not going to be using the heat wrap that the Tomei expreme includes as I've read that it can halve the life of them and lead to cracks appearing in the manifold due to the metal 'crystallizing'.

I currently have GT-SS on at the moment making 335kw atw with stock intake/plenum & manifolds.

The motor is built strong so running higher boost wont be an issue.

From what I've been able to gather the Nismo plenum is rated to 600ps... I'm pretty confident I should be getting more than that with what I've listed above and that the Greddy might be the better option with the mods I'm looking at using. I'd just like to hear from some others out there who know a little more about this than I do. I'm also aware the fuel system is going to need some attention, I have a Nismo pump at the moment and have had one suggestion that the Walbro 400lph intank might just be enough to get the job done.

If anyone has any thoughts or suggestions on which way to go I'd like to hear from you. I've read alot of different opinions out there with many contradictions.... any clarity you can bring to this decision would be well appreciated.

I'll also post up the results of how everything goes when she goes under knife again. I know this question was asked a while back regarding the AEM wideband/egt wifi sensors and nobody out there was using these... I'll let everyone know how this goes too. For those who haven't crossed paths with these they send the live data via wireless network which you can connect to via anything with an internet browser ie) Laptop, iFads & phones etc. No fixed gauges FTW! I plan on using my Android phone for the wideband/egts which will be fixed with velcro where I used to mount my FC Hand controller.

Edited by CruisingFast
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This is what Nismo themselves have to say about their plenum:

At 4800 RPM to 7600 RPM, output improved by an average of 1.8%

IMO unless you really want to drop money - then don't. The stock one has been proven time and time again to hit 450rwkw.

I'd also take the manifolds off now (if the motor isn't in the car), and put stock ones back on. Tomei will crack, it's just a matter of time. Could be 1,000kms or could be 10,000kms irrespective of heat wrap or not. The quality simply isn't good enough.

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The car is running at the moment with the motor, stock manifolds/plenum & GT-SS turbos... The Tomei manifolds are on the way from the states and the 2530's from Japan. I'm still saving for the ID2000's and was thinking about the plenum too... I just want to do as much as I can to get the most benefits from the 2530's. With what I've spent to date a little more now with all the tuning that's to be done for the Flex fuel setup I just wanted to get everything close to where it will most likely stay for as long as it can.

I really hope I didn't just blow $900 on the manifolds, I thought that was the best match for the larger 2530's to help it reach it's full potential... would Ceramic coating inside and out help with the turbo's heat shielded? And a larger plenum like the greddy is going to help with more cool air so that too should bring down the temps right?

That said, atleast I still have the original manifolds and getting them port matched and ported isn't out of the question if the performance would be about the same but more durable.

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It's the metal/welds that fatigue. Coating won't stop them cracking, keeping the heat in would potentially make them worse.

There are 4 users that have had them fail in the past 12 months... And given most people stick with stock ones (ported if you must) - it would likely be a higher failure rate if more people were using them.

And a larger plenum like the greddy is going to help with more cool air so that too should bring down the temps right?

Temps of what?

That's the job of the intercooler and then the fuel that is added in @ tuning stage.

Air volume on the plenum has little to do with Air Temp post cooler. Running @ 20psi+ @ 8000rpm the air wont be sitting around getting hot on a volume basis (and a greddy is marginally larger IIRC - so little it means nothing volume wise).

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I'd also take the manifolds off now (if the motor isn't in the car), and put stock ones back on. Tomei will crack, it's just a matter of time. Could be 1,000kms or could be 10,000kms irrespective of heat wrap or not. The quality simply isn't good enough.

What he said!

The car is running at the moment with the motor, stock manifolds/plenum & GT-SS turbos... The Tomei manifolds are on the way from the states and the 2530's from Japan. I'm still saving for the ID2000's

Been there and done that, twice. First set lasted 15,000 kms or so, second set was 1,000 or 1,500. Forget them! HKS Japan even say to run the standard manifolds (Ask Elrodeo666 who had his HKS 2.8 built by HKS Japan.... That in itself says something!!!!)

ID 2000's. Great choice. Even though they flow enough to be fire hydrants, they idle and drive better than atleast the Sard 800's ever could dream of!

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I might be worried with shuffling (or whatever that term is when the compressor stalls due to the engine being unable to ingest that air at low or no throttle), that is if the HKS hardpipe kit replaces the factory intake piping ("twin turbo" pipe, accordion pipes etc) or is this only a problem with -10's?

The HKS dumps (60mm out) and Apexi front pipe (2x60mm in, 80mm out) might be a restriction at 400-450.

Also ceramic coating the stock manifolds is actually inexpensive, had them both done as a pair for approx $175 inside and out.

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I might be worried with shuffling (or whatever that term is when the compressor stalls due to the engine being unable to ingest that air at low or no throttle), that is if the HKS hardpipe kit replaces the factory intake piping ("twin turbo" pipe, accordion pipes etc) or is this only a problem with -10's?

The problem can occur very much so with 2530's and hard piping kits.

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Hmm.. Tomei expremes for sale... hahaha Damn it, that $900 would've paid for the port matching and porting. Thanks for tips guys... there goes that Tomei/quality/reliable belief I had.

The temps query was referring to the Nismo plenum. I thought if intake temps were lower would help reduce any heat stress to the Tomeis...I also had it wrong thinking the heat wrap was the cause and that you could fix the manifolds so they didn't crack.

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...I also had it wrong thinking the heat wrap was the cause and that you could fix the manifolds so they didn't crack.

The first set of Tomei's I had lasted 10 X longer than the ones that were naked. haha

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The HKS hard pipe kit I got only replaced the rubber OEM pipes, the twin turbo OEM part still remains.

This is an older picture but shows the hard piping kit I've got including the HKS racing pipes & filters, the Air sensors are gone now too ...

IMG_20110701_232059.jpg

Edited by CruisingFast
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RHD have it wrong, probably a bit of jap-lish :)

The exhaust gas temperatures at the front-rear turbine was reduced at an average of 18% at 2400 RPM to 7000 RPM (from nengun, cant find the jap manual atm).

Because logically... How does temps @ the turbo intake (compressor) when it's only come through the air filters and hasn't come near the plenum :)

It's the process of compressing the air, that heats it. Then it goes to inter cooler THEN to plenum.

The reason for the hotter exhaust (in stock form) is only because the stock plenum has slightly uneven distribution to the rear cylinders leaning them off a bit compared to the front 4.

With a good tuner, and matching the injectors etc, the problem is easily worked around as has been done for many, many years.

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Okay that makes sense what you're saying... so the next myth to de bunk is re: Greddy Plenum.

Now I couldn't find anything official stating anything like this, the extra capacity yes though the claim on mid to high range increases seems a little over the top.. assuming these to be exaggerated what would the real numbers be, I tried looking for results etc online but there are none I could find that back up these statements...... it's a local Aussie company who are copying the Greddy plenum for the RB 26.

The RB26DETT intake manifold is approximately 40% larger than the standard intake manifold

which means your engine can flow all the increase boosted air from turbocharger upgrades.

Another advantage of this manifold is that it retains the standard throttle body.

This intake manifold is the 'must have' for RB26DETT with upgraded turbo(s). Not only will

it increase your overall power but it will noticeably increase your mid to high RPM power range.

This manifold can give you a power increase of 15% on standard engine and maximum of40% on a

heavy modified engine.

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Well the way I see it - If Nismo (with their budget & race information) only attained 1.8% and better flow to the rear two cylinders from their upgrade item around your power levels... I cannot logically see how another brand would significantly beat that (and 15-40% is massive claims).

If you were talking 500rwkw+, then cause for argument without a doubt, but we aren't :)

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Okay that makes sense what you're saying... so the next myth to de bunk is re: Greddy Plenum.

Now I couldn't find anything official stating anything like this, the extra capacity yes though the claim on mid to high range increases seems a little over the top.. assuming these to be exaggerated what would the real numbers be, I tried looking for results etc online but there are none I could find that back up these statements...... it's a local Aussie company who are copying the Greddy plenum for the RB 26.

The RB26DETT intake manifold is approximately 40% larger than the standard intake manifold

which means your engine can flow all the increase boosted air from turbocharger upgrades.

Another advantage of this manifold is that it retains the standard throttle body.

This intake manifold is the 'must have' for RB26DETT with upgraded turbo(s). Not only will

it increase your overall power but it will noticeably increase your mid to high RPM power range.

This manifold can give you a power increase of 15% on standard engine and maximum of40% on a

heavy modified engine.

A power increase of 40% on a built engine hey? Well, I'll just rush out and buy one. Better PM PIGGAZ and tell him to sell his massive dollar HKS head too.

Hahahahaha 40% increase my ass. Even 15% on a built engine is a stretch. If it did that sort of increase it would be the first thing any GTR owner did as that's the best power to dollar ratio upgrade on the planet.....that is, if it did actually work as claimed.

It may get a 40% increase if the stock plenum had a restriction in it, like for example, the runners were the same internal diameter as a McDonalds straw

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In all seriousness, there's plenty of results with stock manifolds and stock plenum. Those parts will go over (and have been proven to) 400rwkw.

On a 2.6 if the rest of the car is set up exactly right you'll see a good result, it seems you're happy to buy whatever is needed so get rid of those Tomei manifolds and get stock ones ported, stock plenum just leave be, make sure your dump pipes are big and the exhaust isn't restrictive then get it on E85 and wind the boost in :)

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I would've thought a 10% increase from changing a plenum would be pretty far fetched and going by what Nismo having stated less than 2% increase in mid to high on there plenum I would believe them more than some company selling knock offs. I guess I was reading into the 40% increase in size of the Greddy plenum and thinking yeah a 10% increase if true that could be worth while... even more so when you add E85 ontop.

Thanks guys for taking the time to respond.

I might be worried with shuffling (or whatever that term is when the compressor stalls due to the engine being unable to ingest that air at low or no throttle), that is if the HKS hardpipe kit replaces the factory intake piping ("twin turbo" pipe, accordion pipes etc) or is this only a problem with -10's?

The HKS dumps (60mm out) and Apexi front pipe (2x60mm in, 80mm out) might be a restriction at 400-450.

Also ceramic coating the stock manifolds is actually inexpensive, had them both done as a pair for approx $175 inside and out.

I've heard ppl talking about the shuffling issue before with the twins.... is this a characteristic of the low mount setup and why ppl goto high mounts?

If this problem was to happen what have ppl done in the past to fix this?

Edited by CruisingFast
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A bigger volume plenum will make increasingly more power on a dyno... But it is not practical. What you want is even flow distribution, the Nismo is the most likely to do that.

If you want to be a legend, flow test it first then put it in your engine with individual O2 sensors on each exhaust runner then report back what you find.

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i'll add in what i can, although the people above are immensely more knowledgeable, so take heed off above.

i'm running something very similar to what you're talking. N1 block, 2530's, Nismo Plenum, Tomei Xpreme manifolds, ID1000's, Midori dumps, Midori front pipe, Midori Ti catback, Nismo in-tank pump and flex fuel (i'm still claiming first in Oz damnit! hahah :D) - although using a G4 not Haltech. Not forged internals as far as i know, but they have been WPI processed, JGTC is meant to swear by it and so do others in $$ motorsport... it be interesting to see what you can get away with with stock'ish parts that are WPI processed... anyway...

from my limited understanding with the Nismo plenum is that you will lose a little up top, gain a little in the mid-range but it's more even flow and i think was perhaps an attempt to sort out #6 leaning out a bit. That's how i understood the Nismo to be developed for. Now, perhaps this is important in high $ time attack stuff, but for a predominantly street car, the stock plenum does the job from many an account.

This setup has worked out to be 400rwkw on 85% ethanol at 21psi. I don't have top-end HP cams, (what are you planning on running by the way?) but with some 260'ish cams, with say 24psi or so, 420-430rwkw i reckon will be where you'll end up. Of course lots of tuners love winding in the boost with E85, so 450 perhaps? :D We don't want to chance the internals, so 21 is where we'll be (until i can get some more info on the WPI dealio)

also my fueling setup is very light on compared to others, but we have not found any problems thus far. As you can see, i've only got ID1000's and a drop-in Nismo. Will you be doing much motorsport?

Has your tuner done a flex fuel setup before?

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Daniel touched on a very valid point of cyl6 running lean. If your tuner is experienced in RB26 then they'll probably know to run it a bit richer as a standard thing they do when tuning. Mention it to the tuner just to be sure.

Your cam selection should be right, I would've gone more lift but should be fine. I see you've listed HKS cam gears, in the past there's been some dramas with them (if they're the older style), so if you haven't bought those yet, I'd be looking at alternatives such as Racepace, Tomei, Toda.

You don't mention valve springs. Are you planning on using the stock ones in that head? If you're on E85 you can run much higher boost so it's worth including a set of springs now while the car is in pieces. It depends on how hard you want to push the turbos, if you're going to do what Daniel has done and stay around 21psi for reliability sake then stock springs shouldn't be a drama. If you're going for max HP and just run them as hard as they'll go and still make power (around 30psi sort of boost), then put better springs in. Tomei type A's will do the job fine, also a few regulars on here swear by Supertech.

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