R33 Rb30 Conversion

[mr_rbman]

Just got my car dynoed this past week. Car feels great til about 5500rpm then seems to tail off (note the vg30 turbo, i think) It made 166.8rwkw's@13psi (will post dyno sheet soon) This is in a 1992 R32 gtst. I rebuilt the rb30 to na spec and the head is from an r32 with an rb25de, i just had that checked and the seat tension re done.

Mods are:

full 3" stainless steel exhaust (custom dump pipe)

600x300x75 intercooler with 2.5" piping

Apexi Ap engineering Power FC

Rebuilt vg30 turbo

gtr fuel pump

gtr injectors

z32 afm

(standard airbox with paper filter and no CAI, will be doing this in the next few weeks!)

was a little dissappointed with the power readout but the car feels good (which is what matters) and the tuner says everything seems fine except he believes the turbo is just too small, it also has a loud distinct whistle too which i may have top get checked out seeing as its brand new.

Pretty much everyone i have spoken to have all said that the turbo is where my problem lies but i still thought it would have made around the 190-200rwkw mark? If anyone has any ideas then please fell free to share them!

[Bl4cK32]

Strange. Should be similar results to Cubes'....

Turbo whislte, i would be chasing up especially with it supposedly being rebuilt.

[TTT]

I would have thought that power could have been had with those mods on that boost limit on an RB20 let alone a 30..

[mr_rbman]

darren, turbo has definitely been rebuilt, have the receipt from bill at ats! Am getting the turbo looked at this week hopefully! (cheers for the lend of the cable by the way)

gtst, i would have expected more too! Joel (cubes) i think got 175rwkw's at only 8psi from the rb20t and this is all done on the same dyno!

[TTT]

are you certain your valve springs are up to the task?

I think Joel is not having issues with this and they were tested fine.

just a thought.

when the turbo was rebuilt, was it hi flowed in any way?

or just a stock rebuild.

[mr_rbman]

here's my dyno sheet. One is the engine as n/a when it went in to boostworx (135rwkw's aint too bad at all without boost!), as you can see the torque seems to dip off And the power seems a bit over the place up top. The afr's were really good with 11.9 - 12.0 all through the revs.

[Bl4cK32]

The 135rwkw is about right for the na bit. I had the same result when mine was first tuned, as the cas was farked, it pulled all timing out under boost, and got the same result.

Turbo needs to be looked at though....

Dont forget Cubes and myself have some porting done, so you may require a little more boost to get similar results.

[mr_rbman]

are you certain your valve springs are up to the task?

I think Joel is not having issues with this and they were tested fine.

just a thought.

when the turbo was rebuilt, was it hi flowed in any way?

or just a stock rebuild.

turbo was not hi-flowed in anyway!

The seat tension was checked and was screwed so it was all redone, just like Darren's

[mr_rbman]

The 135rwkw is about right for the na bit. I had the same result when mine was first tuned, as the cas was farked, it pulled all timing out under boost, and got the same result.

Turbo needs to be looked at though....

Dont forget Cubes and myself have some porting done, so you may require a little more boost to get similar results.

ye i did remeber that you guys had the head work done but i thought there was just too much difference, I'm not really too worried cause the car feels great and thats what counts! let dad take it for a quick run through the hills just before and he loves it. He gave it a bit too!

I was also driving through the hills friday night and came up behind a supra and had no probs keepin up with him even accelerating out the corners i was still there so thats not too bad against a 3 litre twin turbo!

[mr_rbman]

i remeber when u first had yours tuned darren you had that problem! what exactly was it and how was it fixed?

[mr_rbman]

i guess also that if yours and joel's both made around 135kws as n/a like mine then that should tell me that its something to do with the turbo side of things???

[Bl4cK32]

i remeber when u first had yours tuned darren you had that problem! what exactly was it and how was it fixed?

Just a stuffed CAS. It just pulled all timing out under boost. Shaun fixed it with some parts off a rb25 cas (its all he had at the workshop) and it worked fine. Had it tuned to roughly 218rwkw.....then the coils shit it

Yer id say turbo due to similar results without one.

[[200]]

I got my rods the other day.

[TTT]

question:

not directly related to Rb30 but I guess it can be included as well.

with compression ratios..

A stock rb30 bottom and stock rb25de head = 8.3:1 comp ratio.

if you had different pistons to make 9:1 comp ratio, everything else being equal in the 2 engines, how much more boost would the lower comp engine need to make same power as high comp engine?

another point is, would a rb25 with 9:1 comp ratio have more/same torque down low (under 3000rpm) as this 8.3:1 comp ratio'd RB30?

and does anyone know what compression ratio a factory RB25DE has.

[Medium Dave]

Hey GTST,

Just from memory from what I have been reading recently in this thread - you need to add 2 psi of boost for every .2 change in cr, and the 9.1:1 will be more tourquy off boost. I could (probably am) be wrong, but I think the answer is about page 50-60ish...

Oh - Cubes, nice work on the guide, as soon as my wallet is in a better mood (lots of bills) I am going to make a start on my RB30

Edited March 6, 2006 by Medium Dave

[TTT]

so in my example, the car with 8.3:1 would need 8 psi extra boost to make the same power as the car with 9.1:1?

shit...

[Cubes]

I believe its 2psi for every .5 of a comp to achieve the same dynamic compression ratio.

I'm checking out your dyno graph now ash.

[Cubes]

I've had a quick look.

Basically it looks the same. I was running the same boost resulting in exactly the same spool but with what looks like a bee's dick more torque, also at ~100km/h you drop torque massively.

BUT by peak power it had tailed off to 11psi and it was valve floating over 4000rpm.

Can you check your ign map via the h/c at around 3800+rpm, I'm guessing there was detonation issues resulting in quite a reduction in ign. timing.

I experienced det at 4000rpm, I'm able to dial up to 21degree's up until this point which no doubt will result in quite a jump in torque, we didn't bother fiddling as it was pumping up the lifters if rev'd over 5000rpm.

At 4000rpm it didn't matter how much ign. timing I pulled out it would ALWAYS still knock and power would go flat BUT knock would reduce slightly.

Shaun said valve float was beginning to set in and by 5000rpm the lifters would pump up. Which sounds nasty. :S

Also... Peak power with the rb20t turbo was made with 9psi (176rwkw).

With the car valve floating I made the same power but earlier in the rpm on 11psi.

As I said we were unable to tweak ign. timing due to valve springs.

I suspect you are getting quite bad boost drop, check it out.

[sky30]

Thought id post this here as it is related to the conversion.

I have a complete R32 RB25 n/a head for sale from my current RB30det, it made 306rwkw with the stock cams. This head is a straight bolt-on to the RB30 block (no welding up galleries), It is in excellent condition and was running on my motor 2 weeks ago, selling due to upgrade to GTR head in my new car.

PM for details if anyone is interested.

[Cubes]

Ash,

I need to see whats going on with your ign map. It looks as if you have quite a large drop in torque around the same 4000rpmish as I.

Initial fiddlings had the base map at 18degree's dropping to as low as 14 to reduce det at 4000rpm, even then it was still spiking up (50+) over 4000rpm but much better than the 100+ it was when running 18degree's at that rpm point. Shaun suspects its the valve float setting in causing a little det and power to flatten out, as 5000rpm approaches the valve float gets so bad the lifters pump up. BUT as stated earlier I am running a higher pressure oil pump so no doubt this is aiding the pump up early in the piece.

Fiddlings since I am able to run 21degree's without det until this ~4000rpm load point where it just sh*ts its self.

Definitely strange how a few hundred rpm earlier I am able to run 7degree's more ignition timing, most likely as Shaun said... Valve float.

Any chance of copying your wot ign values across the rpm table?

I will be after load points 15, 16 and 17.

With regards to boost drop, you can force it to hold by elongating the actuator mounting holes and wedging it away from the turbo using a screw driver, be carefull as its tuned for the boost its set to now running more boost will only send it lean, depending how the fuel map has been setup.

I was experiencing valve float but no lifter pump with the wastegate wired open at around 6000rpm+. Your N/A curve looks much nicer than mine.

Any idea what boost it was running with the wastegate wired open?