R33 Rb30 Conversion

[GTR-Ben]

Drilling tonight and modifying the RB20 powersteering mount.

I will post pics.

[awurth]

Just thought I would throw this in, Mate of mine is doing up a VL with the RB30/25 Conversion. He is running standard rods in it but some how he got his hands on some nissan motor sport forged piston's that weren't available to the public!!!! lucky prick. He is running a custom turbo flowing 600Hp at 6psi. The engine is complete and is about to have my other mate make the inlet and exhaust manifolds up for him. Tremic 5 speed rated to support 600Hp. 750cc injectors. He was tossing up his options between power FC or a Link computer and after talking to his tuner is going for the Link due to being able to remove the AFM. should be a pretty good car when it's complete.

[matlowth]

You sure about that?

My head flow's pretty bloody well and I've got high flowed T07S (650-700hp turbo), and my car needs 3 times the amount of boost to flow that.

I think your mate is telling fibs.

BTW - a turbo doesn't flow 600hp @ whatever PSI. An engine running a turbo @ whatever psi may produce 600hp. A turbo is just an air pump!

Oh - and PS - Don't discount the PowerFC just because you have to run an AFM! My car's running one and I don't have any issues with it! Cold start is perfect out of the box, bolts straight in without modifying the harness, it's very easy to tune, and a most of the part throttle maps only need a bit of tweaking vs. creating from scratch on a Link ECU. Plus it's a 20x20 map for inj & ign!

matt

He is running a custom turbo flowing 600Hp at 6psi.

[Sydneykid]

Hi Mat, the rule of thumb says 600 bhp = ~66 lbs of air per minute. Then all you need to do is look for a compressor map that shows that amount of airlfow at ~6 psi.

The T76 looks likely;

Yep, ~65 lbs of air per minute at 1.5 pressure ratio (7.3 psi).

So, I have no problem with claim from the "mate of awurths", except he must be crazy. Why would you use a 900 bhp + turbo to make 600 bhp? The lag would be obscene, not to mention the piss poor turbo efficiency (~60%).

But, hey it could (theoretically) be done, I just don't know anyone that silly.

[awurth]

I'm not a mechanical genius but one of the first things i got my head around is that everythings to do with flow rates. I'm not dumb, I understand that just cause the turbo can flow that amount of air doesn't mean the motor will produce it. That all comes down to other factors within the motor and tuning. That is beside the piont.

A bit more on that VL. It is in Mackay, Qld. He bought the turbo off a guy in Mackay who had it made up for his Gen III ute, so yes I don't think the compressor efficiency would be desirable on the VL. He is basically running it cause he got the turbo and external Wastegate fairly cheap. He is running different cams (lift and Duration??? but they seem fairly aggressive when compared to normal turbo one's) He has gone for a Link because the turbo has a 4 inch inlet and he really doesn't want the restriction of an AFM, the link is closed loop as well, so that will be very helpfull. the tuner also likes the software with the link (not getting into arguements, I think PowerFC's are great and am considering one for my GTR with RB20 AFM's). I too reckon the power delivery will fairly late and fairly sudden and his clutch will be screaming for mercy after not too long. at least the engine bay will look good with this HUGE turbo sitting there!!!!!

I know you guys would probably want more specific info about it so i will try find out more later and post it.

[GTR-Ben]

Hi Mat, the rule of thumb says 600 bhp = ~66 lbs of air per minute.  Then all you need to do is look for a compressor map that shows that amount of airlfow at ~6 psi.

The T76 looks likely;

 

Yep, ~65 lbs of air per minute at 1.5 pressure ratio (7.3 psi).

So, I have no problem with claim from the "mate of awurths", except he must be crazy.  Why would you use a 900 bhp + turbo to make 600 bhp?  The lag would be obscene, not to mention the piss poor turbo efficiency (~60%).

But, hey it could (theoretically) be done, I just don't know anyone that silly.

How do you read that Graph? What would be a good example of what kind of pressure I need to run with the GT30/40 turbo to get 500HP or so?

[Steve]

GTR-Ben, the airflow across the bottom is straight forward, on the vertical axis is boost pressure - this is absolute pressure, so you need to subtract 1 from the value to get boost that is seen in the manfold

- absolute pressure is the total pressure, including the atmospheric pressure which is 1 bar, thus it needs to be subtracted.

So, drawing a line up from any given airflow point, you can read boost required off the vertical axis, and where in the efficiency map the compressor is working. The line to the left of the map is the surge line.

[Sydneykid]

He has gone for a Link because the turbo has a 4 inch inlet and he really doesn't want the restriction of an AFM

Hi awurth, tell your mate that the car below has AFM's, it makes 1,000 + bhp, runs the 1/4 in 8.4 at 165 mph. Not much of a "restriction" it would seem. BTW it uses a Power FC as well.

The "AFM = restriction" is a myth, you just have to have the right sized one for your application. Spread the word.

[BU5TER]

SK if you were to use a RB26 head on the RB30 in a R33 gtsts would you use the loom in the engine from the RB26 and then run a RB26 power fc with twin afm, or is there a way to run twin AFM with the rb25 loom

[Sydneykid]

A bit more on that VL.  It is in Mackay, Qld.  He bought the turbo off a guy in Mackay who had it made up for his Gen III ute, so yes I don't think the compressor efficiency would be desirable on the VL.  He is basically running it cause he got the turbo and external Wastegate fairly cheap..

Hi awurth, if he got it "cheap" then he could sell it and make some money to buy the right sized turbo. A turbo spec'd for a 5.7 litre pushrod, 2 valve per cylinder V8 is hardly ever going to work on a 3 litre, DOHC, 4 valve per cylinder 6. He should be able to sell the "big" turbo and buy an equally used "smaller" one and have money left over to buy other go faster bits.

Pass that on to "your mate", take it from someone who has tried it. There is no way of overcoming a mismatched turbo, if it's spec'd wrong, it's always going to give a less than desirable/possible result.

[Sydneykid]

SK if you were to use a RB26 head on the RB30 in a R33 gtsts would you use the loom in the engine from the RB26 and then run a RB26 power fc with twin afm, or is there a way to run twin AFM with the rb25 loom

Hi Buster, yes you can run 2 X AFM's with the RB25 loom, but it really goes back to why do you want to run 2 X AFM's?

[BU5TER]

Hi Gary, you once quoted

1 X RB20/25 AFM = 370 bhp = 220 rwkw

1 X Z32 AFM = 420 bhp = 260 rwkw

2 X RB26 AFM's = 475 bhp = 300 rwkw

2 X Z32 AFM's = 700 bhp = 470 rwkw

1 X Q45 AFM = 480 bhp = 300 rwkw

2 X Q45 AFM's = 850 bhp = 550 rwkw

I was planning on running 2 x Z32 AFM's and a power fc pro, I was using one Z32 with my old set up and made 330rwkw but am hoping for a touch more power then that with the new set up which makes me think i'll be needing to use 2 AFM's if I use power fc

[Sydneykid]

Wow Buster, that's an old post. We are almost up to 400 rwkw with a single Q45 AFM now. This Apexi drag car (below) with the 2 X Q45 AFM's making well over 1,000 bhp prompted me into trying for more out of the single Q45. We have not seen any measurable restriction so far. Plus you proved the Z32 AFM 260 rwkw rule of thumb to be out of date with your 330 rwkw.

You can parallel up a pair of AFM's and use them with a GTST ECU, they need to be exactly the same though. Give me a call an I will run you though the process, bit too tricky to do via the keyboard.

I am working on updating the table in light of these and other recent testing results. I will post it when I am confident in using them as a new rule of thumb.

The more you test and push the envelope, the more you learn.

[BU5TER]

Great work Gary, thanks for that info.

Getting back to the RB26 head, is it best to use the RB26 engine loom or swap the sensors over and use the RB25 loom?

[Sydneykid]

Hi Buster, I would use the same stuff. ie; RB25 loom, RB25 ECU, RB25 sensors etc

[KamikazeR33]

SK: how strong is the crankshaft and what aftermarket options are avail?

[Sydneykid]

SK: how strong is the crankshaft and what aftermarket options are avail?

If you mean the RB30 crank, I have seen 900 bhp using a standard crank. We are just about to build one with 1,200 bhp, give me a few months and I will be able to tell you whether or not that is the new benchmark.

As for aftermarket options, well there are lots of choices. Almost every Australian and NZ machine shop has the capacity to make a forged RB30 crank. Add a large number of the US majors to that and you have plenty of choices. Both standard stroke (85 mm) and long stoke, I have seen up to 94 mm stroker cranks for RB30's.

Hope that helps

[GTR-Ben]

Ok it may be getting off the whole RB30 thing, but why do you keep the AFM's Sydneykid? Do they allow for easier tuning?

I have a Linkplus ECU all wired into a GTR loom for use with my RB30 with the GTR head. It is setup to use no AFM's.

[Sydneykid]

Ok it may be getting off the whole RB30 thing, but why do you keep the AFM's Sydneykid? Do they allow for easier tuning?

I have a Linkplus ECU all wired into a GTR loom for use with my RB30 with the GTR head. It is setup to use no AFM's.

HiBen, some people prefer to use MAP's sensors, some prefer AFM's, I just happen to believe that Skylines run nicer on AFM's. I'm not saying that they make more power, or go faster, or use less petrol, or cost less. What I am saying is, for equal power, an AFM equipped Skyline, in all atmospheric conditions, will generally run nicer than a MAP sensor only equipped Skyline. I like my cars to run nice all the time, it's a lot harder than simply making lots of power.

As for Link ECU's, as far as I know they don't work with AFM's, so you have to use MAP sensors for engine load readings.

[Skyrine-Dave]

hey guys,

anyone looked into the safe RPM limit of an RB30?

I have spoken to someone who said that anywhere over 6600rpm is asking for trouble. I was looking at using a 7000rpm limit, but was told i would be treading lightly on reliability.

any info?