R33 Rb30 Conversion

[Cubes]

I hope Andrew doesn't mind but I've attached a comparison of his and AM's.

Andrews at the time of the dyno run was running 260dur Poncams, ~19psi, 3.5" exhaust, ebc, stock exh mani and plenum.

AM's stock rb25de cams and 2 3/4" exhaust, stock exh mani and aftermarket plenum and less boost ~17psi with no ebc and a little valve float starting to develop (lump curve)

The poncams bring boost on earlier and really pump up that mid range, not to mention its running more boost so that too pumps up the mid.

It shall be interesting what happens to AM's once boost is pushed up, possibly cams and an ebc to hold that gate shut until the very last ms.

Going by what it looked like when on lower boost levels and slowly raising it up the graph shape stayed the same from around 90-95km/h but the whole thing simply moves up.

[StockyMcStock]

So where does my dyno graph fit into all this?

[Cubes]

Where does it feel on the road that power begins to lay off?

[StockyMcStock]

ummm...... nowhere? it spins the tyres everywhere in first and 2nd, and i haven't done above 5500rpm in third really. it's hard to tell if the powerband drops anywhere, it certain doesn't feel like it?

[Cubes]

If it pulls nicely to 6000-7000rpm then don't touch it.

I'm assuming thats one of the reasons you went the dohc head? The ability to rev it?

[r33_racer]

ability to rev...pffft. I just wanted two camshafts

[sky30]

I hope Andrew doesn't mind but I've attached a comparison of his and AM's.

Andrews at the time of the dyno run was running 260dur Poncams, ~19psi, 3.5" exhaust, ebc, stock exh mani and plenum.

AM's stock rb25de cams and 2 3/4" exhaust, stock exh mani and aftermarket plenum and less boost ~17psi with no ebc and a little valve float starting to develop (lump curve)

The poncams bring boost on earlier and really pump up that mid range, not to mention its running more boost so that too pumps up the mid.

It shall be interesting what happens to AM's once boost is pushed up, possibly cams and an ebc to hold that gate shut until the very last ms.

Going by what it looked like when on lower boost levels and slowly raising it up the graph shape stayed the same from around 90-95km/h but the whole thing simply moves up.

Joel,

I think that 306rwkw run is with the stock cams, it made 312rwkw with the cams in. Also i always had a 3" exhaust, was meaning to upgrade to 3.5" but never got around to it.

Any way you can plot Stockys twincharge graph on the graph with ours?, maybe work out RPM and gearing of his car compared to speed of our R32 gts.

[Cubes]

Hey Andew,

Going by the date that was the run done on the 2005 dyno day late last year.

Not sure what made me think it was a 3.5.. maybe the noise, it did sound awesome as Shaun gave it that blip.

I'll check out stocky's.

[Sydneykid]

ummm...... nowhere? it spins the tyres everywhere in first and 2nd,

Sounds like it needs decent tyres and suspension

cheers

[ISL33P]

ISL33P,

You do a plenum to suit the r32 rb25de?

Something that may require sending in our own inlet manifold to be chopped up or can you sort out that side of things?

The std plenums really do leave the rb30det feeling a bit like a high powered diesel.

please pm for any enquiries as i dont want this too appear as a advert for myself this is an info thread and a very popular, not to be used to promote my own interests unlike others out there

Discussion is knowledge, knowledge is power and without discussion the ignorant die a long, slow and frustrated life.

Hi Ariel, "experts", I guess that would include me

If you wish to put yourself in that category, feel free to do so, but please change your sig because you do think you know everything

and I have most definitely "tried it", in fact several “its”. They all fail to produce higher average power levels on RB25DET's up to their limit of 7,250 rpm (equivalent airflow to 6,000 rpm in an RB30).

Looking at the dyno graphs I see exactly the same result, lower average power up to 5,750 rpm. This means the standard plenum equipped engine would be faster accelerating from 3,000 rpm to 5,750 rpm in every gear than the aftermarket plenum equipped engine.

Personally, on an RB30 with standard internals, I would much rather have my max power at 5,250 rpm (using the standard plenum), instead of 6,000 rpm (using an aftermarket plenum). After all higher rpm = shorter engine life.

Revs = power and you yourself say the standard plenum causes a restriction which does not help this equation. Engine life comes with a properly prepared engine, you, a self-proclaimed expert should know that

My own rb30, purchased in 1998 with 157,000k’s, went thru a lot and I owned it for 6 yrs, 4 yrs (more than 70,000k’s) at my hands/feet and is still going to this day (to the best of my knowledge) making at least 370rwhp (stopped making power at 6200, the standard factory imposed rev limit) with completely standard internals and it used to get revved, although accidentally during burnouts, racing or a missed gear, to more than 8000rpm but more commonly 7250 rev limited (why so high when it stopped making power at 1000rpm earlier, simply becuase i loved the sound of it revving with the wastegate screaming and so did everyone else ). Don't know about you, but that's what i call reliability and repeatability, the essence of "engine life".

We have no idea of the comparable atmospheric conditions prevailing on the days that the dyno runs were performed. The dyno runs do not appear to have been carried out in Shoot Out mode by an accredited workshop, hence no atmospheric information is shown. All I have done in the previous post is to comment on the information as supplied.

Sounds like we have a Dyno Dynamics rep on board, how lucky we are

Remember that boost is simply a measure of resistance to airflow, lower boost should indicate less resistance. Which I am sure the proponents of aftermarket plenums would quickly lay claim to. Less resistance should lead to higher airflow and higher airflow means more power.

Since we have been told that nothing else was changed, I can only conclude that the aftermarket plenum has less resistance but fails to turn that increased airflow into increased power. Based on the evidence I would maintain that this plenum, like all the others I have tested, has poor distribution which results in the lower power output.

Hence the lower power output is not in fact due to lower boost, but due to poor distribution of the increased airflow. As is common, at higher rpm the aftermarket plenum's poor distrbution becomes less of a problem.

Poor distribution is simply a matter of poor plenum design. Maybe you should try some of the more proven and tested plenums before jumping to conclusions that they all are the same. edit - there are plenty of people out there that claim results, so maybe you should try a few more

Edited November 17, 2006 by ISL33P

[handyandy]

Hi Guys, i'm ready to send my block off to get cleaned, crank, rods and pistons done ect.

I just want to make sure that the parts i have are all ok to use and havn't missed anything.

My list is....

32 gtr head on rb30e block.

Forged pistons and rods.

Stock crank rb30

Acl Big and main bearings

Standard rb26dett h/g. or metal one ? Will deck the block to achieve between 8.5 to 9 c/r.

Arp rb25det head studs

N1 oil pump with crank collar

2 x 1.5mm oil restrictors

2 x rb25det knock sensors

rb25det oil pressure sensor

Dayco Timing belt 94407 with two tensioners

rb25det engine mounts, pullys and tensioner. + 1 for above the water pump

I'll then build it up with reference to cubes's pdf file.

Sorry for going though all this but theres so many pages to read.

I'm at 66 at the moment

Thanks again, Simon.

[Bl4cK32]

id go for king race bearing as used by cubes and myself. no problems so far, and going strong.

steer clear of the n1 pump unless u want it for track work..its not needed unless its a constant high revving motor...

[r33_racer]

and you said your going with two 1.5mm restrictors for the 26 head when std they have one 2mm restrictor. Your actually encouraging more oil to goto the head then std. Stick with the one 1.5 hey and leave the back one blocked off....or is it the front one?

[handyandy]

Bl4cK32.... which pump would be best then? It wont see the track too much.

will the stock rb25det oil pump sufice?

r33_racer... sorry one x 1.5 oil restrictor.

Does any know which one should have the restrictor in it?

Thanks for the help, Simon.

Edited November 18, 2006 by handyandy

[shanef]

u'll be fine with the rb25 pump, just get it checked to see if it's fine, and it mite pay to put a 'collar' on the crank for that extra bit of drive for the oil pump

rb's have a tendancy to wash oil up the back of the head, so would it be best to block off the rear one?

[r33_racer]

got a pic of the oil pump mods done so far for the dry sump setup. We used a slightly modified rb25 front head return as our main feed with -10 fittings, coincidently the std return has the same id as -10 so it worked out well. We cut the top off the oil pump and i tigged up the hole. Quite abit of stuffing around checking belt clearance, damper clearance, swaybar and the rest...but it looks like it will work. The cut down aircon bracket to hold the pump. I will post better pics when it is fully finished. It just needs some tags to pick up the adjusting bolt for the slide tensioning if you get what i mean.

[shanef]

i see u modified the pump to seal off the front, instead of making one from scratch, noice idea

[Sydneykid]

Sounds like we have a Dyno Dynamics rep on board, how lucky we are

Poor distribution is simply a matter of poor plenum design. Maybe you should try some of the more proven and tested plenums before jumping to conclusions that they all are the same. edit - there are plenty of people out there that claim results, so maybe you should try a few more

Nope, my comment was simply in relation to atmospheric conditions for the dyno runs comparisons, not an add for DD.

Based on the evidence supplied, my conclusioin is that this particular penum has poor distribution. If you have evidence to the contrary please post it up.

I am willing and able to test ANY plenum at any time on the car and/or on the flow bench, plenty of guys have taken me up on that. So far I haven't found one single aftermarket plenum that makes higher average power on an RB25 cylinder head up to 300 rwkw.

Please feel free to send me a plenum at any time and I will test it and publish the results. If it produces higher average power, then I will gladly pay you for it. If it produces lower average power then you can pay me for the labour to R&R it.

Over to you

cheers

[shanef]

Dammit why arent you here in qld!!!

[Cubes]

SK,

Please don't take offence at anything I say I'm just trying to get my head around where you are coming from as to myself its as clear as day the wider power band is considerably better than a peaky one even though it 'may' loose a little through the mid range.

But first...

I'm curious how you tell it has poor distribution when the car clearly had a little boost control issue prior to the plenum and after the plenum ign wasn't tuned to suit. There was no boost controller connected so the external wastegate should have held boost perfectly to start off with, not spike up then tail off.

Possibly an issue some where else that was accidentally sorted when reworking i/c piping etc.

The plenum was simply dropped on, afr's set back to 12:1 due to it running larger 800cc twin sprays (no ign tweaking) and a power run performed.

Either way I really do believe its worth while for the RB30DET running a GT35r even when running the lower 8psi and making under 200rwkw. I have no results with one running a gt30r so I can't conclude.

Consider...

The rpm drops between gears, selecting the next gear your going to be in more power with a wider power band.

A narrow power band that may make more power earlier will no doubt be quicker accelerating out of a corner in a given gear but those benefits are over once that car selects the next gear as they will drop to say 160rwkw then have to build up where as one with the wider power band may only drop to 240rwkw then build up to 270rwkw. So a much greater average power for the given gear ratio's which should translate to quicker 0-100 and quicker 1/4 times.

The car with the narrow power band will also loose out at higher road speeds, possibly resulting in lower TS 1/4 speeds.

Hope that made sense.

EDIT: We really need some results with a GT30r. From what I've seen before the GT30r .82 tends to fall over a touch before 6000rpm at 1bar ~250rwkw with power flattening off from around mid 4000rpm.

Should this be just the turbo being a touch small on the hot side or not has yet to be seen. Without flicking back posts the dude who runs GT30r on his Rb30DET with a plenum please take note of where it makes its power. If power extends up close to 7000rpm without flattening off majorly then awesome.

Edited November 20, 2006 by Cubes