R33 Rb30 Conversion

[Cubes]

R32 RB20DET
Gear Ratios
1st - 3.321
2nd - 1.902
3rd - 1.308
4th - 1.000
5th - 0.759
Reverse - 3.636
Final - 4.300

RB25DET
Gear Ratios
1st - 3.214
2nd - 1.925
3rd - 1.302
4th - 1.000
5th - 0.752
Reverse - 3.369
Final - 4.363

Z32 300ZX
Gear Ratios
1st : 3.214:1
2nd : 1.925:1
3rd : 1.302:1
4th : 1.000:1
5th : 0.752:1
Final Drive : 3.692
Reverse : 3.369:1

Z31 300ZX
1st : 3.324
2nd : 2.077
3rd : 1.360
4th : 1.000
5th : 0.751

VL Turbo
Gear Ratios
1st: 3.580:1
2nd: 2.077:1
3rd: 1.360:1
4th: 1.000:1
5th: 0.760:1
reverse: 3.636:1

RB25DET gear ratio's are hard to come by, I found these on SAU some time back.

Strange enough they are the same as a reliable Z32 300ZX source.

Is any one able to confirm the RB25DET gearbox ratios?

For those that want to fiddle...

http://racingdownloads.com/racing_software-22.html

[Cubes]

R32 RB20DET Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2777 (to 3723)		  -2991 (to 4009)
 2 -> 3		 -2030 (to 4470)		  -2186 (to 4814)
 3 -> 4		 -1531 (to 4969)		  -1648 (to 5352)
 4 -> 5		 -1566 (to 4934)		  -1687 (to 5313)

RB25DET Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2607 (to 3893)		  -2807 (to 4193)
 2 -> 3		 -2104 (to 4396)		  -2265 (to 4735)
 3 -> 4		 -1508 (to 4992)		  -1624 (to 5376)
 4 -> 5		 -1612 (to 4888)		  -1736 (to 5264)

VLT Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2729 (to 3771)		  -2939 (to 4061)
 2 -> 3		 -2244 (to 4256)		  -2416 (to 4584)
 3 -> 4		 -1721 (to 4779)		  -1853 (to 5147)
 4 -> 5		 -1560 (to 4940)		  -1680 (to 5320)

Z31 Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2438 (to 4062)		  -2626 (to 4374)
 2 -> 3		 -2244 (to 4256)		  -2416 (to 4584)
 3 -> 4		 -1721 (to 4779)		  -1853 (to 5147)
 4 -> 5		 -1560 (to 4940)		  -1680 (to 5320)

[mr_rbman]

For those that are interested I've made a dyno spool comparison of the mine, sky30's and Ash's.

The reason mine jumps up sharply is it basically spools up instantly at that rpm, if shaun had loaded the car up at a lower rpm ~1500rpm it would have been a slightly better indicator of how it spools in the real early rpm.

I haven't attached bl4ck32's 218rwkw run as he doesn't have a print out.

His little plain bearing MQT/Dynamic Turbochargers RB20 highflow makes 218rwkw on 16psi and it spools ever so slightly better than the vg30det turbo shown here.

I think if ash were to get an ebc on to his nice tight little actuator he may bring full spool in slightly earlier, which actually would look too bad.

Dial some more boost in and it should hold power a little better than the .82. BUT it is difficult to tell as sky30 is making a shiet load more power/airflow at that rpm so ash's power curve very well may follow sky30's rapid nose over.

I really do believe this rpm/airflow/velocity point is the limitation of the standard exhaust manifold.

Especially when you see blokes like 88sillouete or what ever his alias is running a nice exh. manifold, stock head, td06-20g and he flicks it to 7200rpm no problems.

Ash,

At 100km/h yours is making a bee's dick more power than a healthy R33 RB25DET running 13psi to make a total of 200rwkw, usual mods pfc etc.

80km/h you are down 18rwkw compared to the rb25det where as sky30 is the same..

So essentially... Sky30's RB30DET GT35r .82 will feel the same at 80km/h as an rb25det running the stock turbo at 13psi.

Impressive when you look at it like that.

60km/h... who knows, most likely they will be the same, if not the rb30det will have the upper hand as 60km/h is some where around 2000rpm.

If one was able to get the 1.06 holding power until 7000rpm I think it would be a rather drivable street car with a downlow (up to 3000-3500rpm) stock rb25det power delivery that simply becomes more and more insane as rpm's increase. I hope that makes sense if you visualise the power curve.

good work Joel, looking at the spool comparison makes me think something is definitely not quite right with my car!

Shaun did also say that i need more tension on the actuator as he said it seemed to be a bit loose.

Nice work Gav! Cars looking good!

[Sydneykid]

R32 RB20DET Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2777 (to 3723)		  -2991 (to 4009)
 2 -> 3		 -2030 (to 4470)		  -2186 (to 4814)
 3 -> 4		 -1531 (to 4969)		  -1648 (to 5352)
 4 -> 5		 -1566 (to 4934)		  -1687 (to 5313)

RB25DET Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2607 (to 3893)		  -2807 (to 4193)
 2 -> 3		 -2104 (to 4396)		  -2265 (to 4735)
 3 -> 4		 -1508 (to 4992)		  -1624 (to 5376)
 4 -> 5		 -1612 (to 4888)		  -1736 (to 5264)

VLT Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2729 (to 3771)		  -2939 (to 4061)
 2 -> 3		 -2244 (to 4256)		  -2416 (to 4584)
 3 -> 4		 -1721 (to 4779)		  -1853 (to 5147)
 4 -> 5		 -1560 (to 4940)		  -1680 (to 5320)

Z31 Gearbox

Gear Change  RPM drop (change @6500)  RPM drop (change @7000)
-------------------------------------------------------------
 1 -> 2		 -2438 (to 4062)		  -2626 (to 4374)
 2 -> 3		 -2244 (to 4256)		  -2416 (to 4584)
 3 -> 4		 -1721 (to 4779)		  -1853 (to 5147)
 4 -> 5		 -1560 (to 4940)		  -1680 (to 5320)

Wow, the memory isn't that bad, the VLT box has the extra 213 rpm drop on the 3 --> 4 change compared to the RB25 box. In fact the VLT box has wider spacing between all gears, except 4 --> 5 which is irrelevant anyway.

cheers

[sky30]

Joel, id be very interested if you could do a similar dyno camparison on torque readings between mine, yours and ash's cars.

Ash, What RPM do you get ful boost at??

I wouldnt be too dissapointed, a mate of mine runs the 1.06 housing on his VLT and doesn't get full boost till around 4200RPM.....

[rb30gtr]

Hey guys,

Just on that subject of when boost comes one at what rpm, I have a r32 GTR and I put a gt35r with a tiny .63 rear housing on it with ext gate, I was after early spool for easy street driving and a more useably torque curve. With 15 psi and 310 rwkws it comes on boost earlier than the standard twins did and holds great boost and a firm curve to 8500 rpm.

When I had decided to go for such a small housing I was warned by many modders that I would get pressure and heat problems due to the housing being to small but all it has been is an excellent street setup.

Oh yeh and thnx for the ratios guys I will most definatly be keeping my gtr diff.

Cheers.

p.s My mate is as we speak setting up his rb30 bottom with 34gtt head for his drfit 32gtst he also is running ext gate and a .63 housing will let you know how it goes.

[sky30]

Hey guys,

Just on that subject of when boost comes one at what rpm, I have a r32 GTR and I put a gt35r with a tiny .63 rear housing on it with ext gate, I was after early spool for easy street driving and a more useably torque curve. With 15 psi and 310 rwkws it comes on boost earlier than the standard twins did and holds great boost and a firm curve to 8500 rpm.

When I had decided to go for such a small housing I was warned by many modders that I would get pressure and heat problems due to the housing being to small but all it has been is an excellent street setup.

Oh yeh and thnx for the ratios guys I will most definatly be keeping my gtr diff.

Cheers.

p.s My mate is as we speak setting up his rb30 bottom with 34gtt head for his drfit 32gtst he also is running ext gate and a .63 housing will let you know how it goes.

Sounds good, What RPM are you making full boost at? And is the engine a RB20 or RB26??

[Cubes]

Definitely sounds interesting...

[Bl4cK32]

With 15 psi and 310 rwkws

can we see a dyno printout?

[mr_rbman]

Joel, id be very interested if you could do a similar dyno camparison on torque readings between mine, yours and ash's cars.

Ash, What RPM do you get ful boost at??

I wouldnt be too dissapointed, a mate of mine runs the 1.06 housing on his VLT and doesn't get full boost till around 4200RPM.....

i'm getting 15psi by 3900rpm, i love this motor and turbo, driving home from work last night (1:30am) was about 4degrees, i just put it into thrid from second and put my foot down and the thing just shoves you back in your seat and pulls so had to the rev limiter!

[Rolls]

I wouldnt be too dissapointed, a mate of mine runs the 1.06 housing on his VLT and doesn't get full boost till around 4200RPM.....

Just out of curiousity why do people run such big rear a/r's surely a ~.8 would be far more suitable unless its a drag/street car.

[Craved]

depending on the turbo's, the rear AR will limit exhaust flow and thus limit power levels..

[Cubes]

Just out of curiousity why do people run such big rear a/r's surely a ~.8 would be far more suitable unless its a drag/street car.

When an offer presents its self that is too good to refuse (1k) and is internal gate that is basically bolt up.

[sky30]

joel, howd you go with thay torque comparison?

[Cubes]

I'll get around to it.

What sized wheels are you running Andrew?

[mr_rbman]

Just out of curiousity why do people run such big rear a/r's surely a ~.8 would be far more suitable unless its a drag/street car.

i probably ideally wanted a .82 but at the moment you can't get a 35/40 with an internal gate (wanted this for the more stocky look) but when the 35/40 came up for sale at a really good price with the 1.06 housing i couldn't refuse and to be honest i haven't regretted it for a second, it is very streetable with the torque the Rb30 produces and i'm only going through 10L/100kms of fuel now due to not it being on boost all the time! Just need some new diff gears now so that i can use first and second a little more!

Edited May 25, 2006 by mr_rbman

[paulr33]

rather than diff gear change, affecting the whole drivetrain why not just alter 1st and 2nd?

[FORZA-MOTORSPORT]

Hi guys just finished my 25/30 conversion, car idles fine on cold start then once she warms up idles less them 400rpm any ideas why?? Then when driving her she stalls when i stop, at idle, i think she is running a bit too lean, i do have a pfc and a hand controller but im not sure how to change the idle, afm or injector duty cycle, should i do this or leave it to an expert? My specs are as follows r32 GTS4 rb25 non vtec head 3L rb30 bottom end, pfc, gtr fuel pump, stock afm, gt3540 turbo, tial 44 external wastegate, stock injectors and tb etc.

Edited May 25, 2006 by FOOLBOOST

[Craved]

aac valve adjustment on the plenum?

check the power FC FAQ in paulr33 sig above your post for FC related options

[FORZA-MOTORSPORT]

Ok thanks, had already tried adjusting aac valve and it didnt make any noticeable difference, think ill just get her towed down to shawn at boostworx