What You Guys Think Of My Rb21?

[vr4ust]

Hey guys im building an rb21det for my r32 gtst im over the ditch in NZ and havent heard much or cant find much info on these engines... anyway ill rattle off da specs

rb20det block bored to 2.1 litres

port polished head

standard cams reground to 264degree specs

custom wiseco forged pistons

forged h beam rods

trust metal 1.5mm headgasket

SSi stainless steel manifold

Garrett GT3040R turbo .82 exhaust housing

44mm Tial wastegate

blitz dual sbc

trust airnx filter

550cc injectors

Greddy emanage ultimate

full 3inch exhaust

DSR front mount

sard fpr

external coils and leads

walbro 255 internal fuel pump

ACL race bearings

prob something else engine wise but bet i left it out haha... anyway now for the questions, im aiming for 300 to 350 rwhp id think i should be able to achieve this with current mods, im a apprentice mechanic at a performance garage so i have a fair idea about stuff... also has anyone had experience with the emanage ultimate? you reckon it'll be fine for my application? i like the fact that its a piggy back but have heard mixed reviews for it... also does anyone have experience with the GT3040R? do you have any idea when boost will come on? i know she'll be laggy but i like that but should be a lil better than a rb20 because of 2.1 litres and headwork right? anyway ill post pics of the build and keep you updated with wat it does on the dyno just waitin for rotating assembly to be balanced, well cheers for your time any comments and advice would be appreciated!

Edited June 5, 2008 by vr4ust

[Sydneykid]

Why don't you stick an RB25 or RB26 crank in it?.....................in fact, have you tried a seach on "RB24's"? There is plenty of information on them.

Cheers

Gary

[vr4ust]

yea i have thought of that but i like the 21's and already have all the stuff love the sound of the 20 and figured the 21 would sound the closest haha

[Busky2k]

RB21 + 3040 + 0.82 is gonna be a light bulb and that turbo combo way too big for 300-350rwhp. Have you bought it already? A 3071 0.63 would give you that power easily and be much more responsive and make a much faster car too.

[AD4M]

RB21 + 3040 + 0.82 is gonna be a light bulb and that turbo combo way too big for 300-350rwhp. Have you bought it already? A 3071 0.63 would give you that power easily and be much more responsive and make a much faster car too.

go with a .63 rear and it will be fine, not laggy and not snappy power.

my motor with the 3040 .63 and stock internals apart from the fitment of 264 9.1 hks cams made 346rwhp at 22psi on a tired motor.

if your going to build the motor im more than confidant you'll make the power easy!

[vr4ust]

Yea already have all parts just waitin for rotating assembly to be balanced, yea i thought it was a .63 but looked inside it says 0.82in inside the exhaust housing, so far too big you reckon? what sorta revs would full boost be comin on at? ill prob look at something smaller although i dont mind a bit of lag like full boost 4500rpm max haha...

[vr4ust]

go with a .63 rear and it will be fine, not laggy and not snappy power.

my motor with the 3040 .63 and stock internals apart from the fitment of 264 9.1 hks cams made 346rwhp at 22psi on a tired motor.

if your going to build the motor im more than confidant you'll make the power easy!

Hey wat rpm does your car come on full boost? wats your rpm limit set at?

[Roy]

Sneak a bit of compression in there as well. And be careful not to put a larger duration cam in there only to choke it up with back pressure and small exhaust housing

[vr4ust]

sneak some compression? its gotta 1.5mm trust metal headgasket but the pistons are domed, would be interesting to see wat the comp ratio would be? hey have you got that grey r32 with black front kit on youtube tdo6? f**kin loooooooove that car spesh the video where it takes off and you almost dont make the corner and do the styley 3rd gear escape was sick!!! (hope it was you im talking bout haha) o and wat you think of the .82 exhaust housing far to big?

[AD4M]

thats gonna be de-comped a fair bit.

I was seeing fullboost around 3700 on the tacho in the car in 4th gear it was more like 3500 and limiter is set to 7000 cos there was no point reving it to hard if it wasnt making anymore power..

82 is large but i wouldnt underestimate it just yet until you try it on the car, swaping the rear housing over if its too laggy isnt a stressfull job so my advice is just try it first

looking over your mod list again i wouldnt rule out 400-450hp when leaning on it, swapping the rear housing wont make you loose power, it will just shift the point it takes place

[vr4ust]

yea will be my daily driverso dont really wanna be runnin on its limits... yea spose ill try the 82 housing see wat happens?

[R31Nismoid]

If you only want a max of 260rwkw, ditch the GT30/.82 idea. Get something like a 3071 with a .63, will meet your target and be MUCH more responsive

Or something - TD06 like tRoy Its a great turbo for the RB20

[Roy]

sneak some compression? its gotta 1.5mm trust metal headgasket but the pistons are domed, would be interesting to see wat the comp ratio would be? hey have you got that grey r32 with black front kit on youtube tdo6? f**kin loooooooove that car spesh the video where it takes off and you almost dont make the corner and do the styley 3rd gear escape was sick!!! (hope it was you im talking bout haha) o and wat you think of the .82 exhaust housing far to big?

sounds like me if i am missing corners

As Ash said the 3040 is capable of 330-350rwkws which is going to take lots of boost and revs in an RB20. Even with the smaller exhaust housing its not going to have great transient response (throttle response) I would be inclined to try an external gate 3071 but probably a 3076. 3071 will be punchier then the 3076 but will not comfortably make over 260rwkws. 3076 will see you in the 280-300rwkw area which if the motor is rebuilt with pistons will do quite happily. Remembering the 3040 isnt a great turbo even on RB25s etc where over the years ppl have tended to steer clear of them and go 3076, so if an enbgine with 9.0:1 compression and an extra 500cc cant get the best out of the 3040 then the RB20 wont love it.

That all said do a search for Legend01, he ran a 3040 on a std RB20 then a forged RB24 and quite liked it, so woudl copy the trim and spec 3040 he had

Headwork can help make power, but at the same time get it wrong and it can cost you some low rpm velocity which again hurts response. I would stick with simple match porting and basic cleaning up casting imperfections. With regards to cams i would stick with std then after the setup is sorted maybe try the smallest Tomei Poncams (256 duration). This way you can see if they help, if so keep them , if not sell them for only a small $ loss.

Personally if you already have the 3040 then sure keep it.

[wolverine]

legend01 has a forged RB2.1 with GT3040 turbine is 0.82. also with extrude honing of turbine, comp covers and extrude honed hks cast manifold, port matching and a tidy up of the head plus larger cams?

[grandmasterb]

Looks like a good engine combo but its interesting that you decided to regrind the stock cams straight off the bat???

Im looking forward to seeing the end results as its somewhat "similar" if my motor lets go again

OT: Adam i noticed you said you had HKS 264 cams with 9.1mm lift, are you positive they are 9.1 or 9.0??? Reason i ask is that i've got the same cams that im about to drop into my stock 20 and spec sheet stated 9.0mm direct drop in meaning not needing upgraded valve springs.

Cheers Ben

[vr4ust]

Yea i brought the block and head already done so just gonna chuck it in see wat happens! hey so this legend guy has already put a .82 gt3040r on a rb21?? i should def get hold of him, so any ideas wat i should be able to get outta this engine with some sorta decent reliabilty? i know im asking how long a piece of string is but my engine fully forged so im guessin 350 to 400 rwhp should be good although i have never really heard of many of them get much higher so it must be pretty highly strung by then?

[Sydneykid]

yea i have thought of that but i like the 21's and already have all the stuff love the sound of the 20 and figured the 21 would sound the closest haha

An RB24 doesn't really sound any different to an RB20, still revs the same, just a bit angrier.

Cheers

Gary

[vr4ust]

haha yea i was just bein a smartass but yea i have never heard one in real life, i have to say the rb20det is the best sounding rb engine in MY opinion tho

[murrayis]

Yes but a rb24 will rev to 9500RPM

[STATUS]

Yea already have all parts just waitin for rotating assembly to be balanced, yea i thought it was a .63 but looked inside it says 0.82in inside the exhaust housing, so far too big you reckon? what sorta revs would full boost be comin on at? ill prob look at something smaller although i dont mind a bit of lag like full boost 4500rpm max haha...

i reckon closer to 5000,