Difference Between Rb20, Rb25De And Rb25Det Visually

[adam999111]

hi, i am going to look at an r32 gts-t, and it apparently has a rb25 motor and gearbox in it.

i am a bit suspect as to if he is telling the truth and would just like to know of the obvious tell tail signs as to which motor it has.

please no answers like ones a 2L and one a 2.5L

what i know and correct me if i'm wrong and please add anything YOUR HELP WILL BE MUCH APPRECIATED

rb20det:

vlave cover is flat the whole way across

intake runners (flatter at the top than rb25)

no bump on timing cover on intake side

rb25det:

valve cover is raised towards the back

intake runners are slightly higher and not flat across the top

bump/petrusion on timing belt cover on intake side

and i know nothing about the difference between the rb25de+t and a rb25det (please tell me that too if known)

i am ok in telling the difference between the gearboxes as they are completely different in size rb25 1 being alot larger

and the differences between r33 gts-t diff and a r32 gts-t diff if any

Edited February 2, 2011 by adam999111

[bubba]

RB20DET: mostly as you said.. flat cam covers, no bulge in cam belt cover (bulge is for VCT solenoid). Later RB20's actually say RB20 on the cam belt cover. Intake runners, where the top half of the manifold bolts to the runners, the RB20's last two runners are offset from the front 4.

RB25DET: cam covers have raised sections at the rear, cam belt cover has bulge for VCT, will also be a VCT solenoid on the intake side of the head, just behind the cam belt cover (at least that's where it is on my Neo).

RB25DE: If it's from an R32 it will look pretty much like an RB20 (no VCT), if it's from an R33 it will have VCT.

I doubt you would be able to visually tell whether it's an RB25DE+T or a straight up RB25DET.

You could always get an extendy mirror thing and have a look at the engine number..

[adam999111]

yeh thanks,

at least thats cleared it up a little, im not to keen on engine numbers as people generally restamp them if they change motors but i will be also be checking that too.

ALSO: would you know the difference between an r32 gts-t diff and a r33 gts-t diff

from what i have read on the net and here they are both r200 diffs just with a different gear ratio 4.33 and 4.11 respectively.

are is one weaker than the other or they same strength?

[bubba]

It's pretty hard to grind back an engine number enough to restamp it, people generally only stamp the old numbers on a brand new block.

There should also be a cast engine model (RB20 etc) on the exhaust side of the block, below the manifold and pretty much on cyl.1

As for the diffs, they are pretty much the same.

AFAIK standard manual 32gtst diffs are 4.3ish:1 (32gtr's are 4.1:1) while 33gtst manuals are 4.1:1

Gearboxes on the other hand... the R33 GTSt has a FAR superior gearbox, if the car has had an RB25 conversion then I would hope it has the gearbox as well.. to put an RB25t gearbox in my car (including a custom tailshaft, new slave cylinder AND doing the work myself) was a $2.5k adventure.

[adam999111]

yeh i hope he has done the gearbox also (he said he has).

as with the engine numbers lets say that i know someone that has grinded back the numbers on an rb30 and restamped the 25 numbers on it for a 30/25 conversion to pass the pits when getting registered

[bubba]

Nice, I didn't bother, they licensed my 3L pretty easily.

Do you know the visual differences between the boxes? The RB25t box is considerably larger than the RB20 box, you should be able to see some modifications to the gearbox crossmember and also the slave cylinder and speedo drive are different orientations (sorry, can't remember which way though)