RB25 turbo conversion on RB20?

[SlowGTS-t]

Here is my definition of turbo lag.

Lag is the difference between when the car comes on boost in 1st gear and 5th gear

Mine is laggy, boost by 3500rpm in 5th and 4500rpm in 1st if I floor it from 2000rpm.

[lowlux]

i was driving around last night and noticed that i actually get full boost in first buy 2900 and a little lower in 2nd etc,so really thats no bad at all for a vg30 turbo

[HRthirtyone]

hey lowlux, r u serious? thats slightly better than my standard turbo! wtf.. what motor are you sportin? the red top?

i saw a vg turbs for $550 and wasnt interested cos i thought they'd spool up by around 4000, from what i had read.

can u tell us what mods are on your thirty two plz? kummmaaan!

what kinda power ya gettin?...

[Cool Hand Luke]

I think there are two different versions on what people call lag here. From what ive understood lag would be accelerationg slowly to 4000rpm and booting it, how long it takes to reach full boost is how much lag there is. Not when it makes boost.... Has anyone ever tried a RB25 compressor and core with a vg30 exhaust housing? Ive heard its a really good combination

[lowlux]

yups its a redtop eccs rb20det with pod,3" exaust, fmic with 2 1/2" piping and a chipped ecu. And im only getting 139rwks but had to back off cause it was running lean (long story) but im still wanting more and to get anymore out of the rb20 ill have to spend money where as the rb30/25 will make a heap more usable power for less money

[HRthirtyone]

yea i havent had mine for long, and since dead stock was 105rwkw i was hopin for around 130-140rwkw with the mods you have listed... what kind of boost u runnin?

is it runnin lean cos of stnd fuel pump? cos on meggalaz site he said he upgraded to "bosch 070 model" to fix that problem.

[DCIEVE]

lowlux: what chip did you use?

do you have a larger fuel pump

[bbenny]

Hey guys, need some quick advice here.

whats the difference between a VG30DET turbo and the RB25 turbo? which is better to bolt to an RB20?

There is a guy selling the VG30 turbo at around $350 are they as good as an RB25 turbo, because all the RB25 turbos i see for sale are alot more expensive.

[Mr Rb20]

bbenny, go the RB25, that's what i am using and i wouldn't change it for any other turbo.

Well worth the money.

If you read through this thread, everyone is saying the same thing and i can say from experience, it is the best turbo to use on a RB20.

[bbenny]

Yeah that was the impression i was getting, i think i will go the RB25.

thanks Mr RB20

[Cool Hand Luke]

The RB20 that i went for a drive in was pretty impressive, and it still had std dump pipe, crap fuel pump, std intercooler and was pinging at onl 12psi. Go for it, i cant wait to get mine!

[Cubes]

Luke... I actually think the SR20DET's are way nicer to drive (torque etc) on the street than the RB20DET.

Once on boost they are good but so are the SR20det's

[Cool Hand Luke]

Everyone has a SR20 180, have only seen 1 or 2 other RB20's. Plus even tho sr's have more mid range, the rb20 will rev further. An RB's has about 4500rpm of usable power if you put the 25 turbo on it, what does the sr have?

[Cubes]

I honestly don't know anything about the SR all i know is until 5500rpm they totally kick my arse.. Well Nightcrawlers did in third gear from around 80kays.

As soon as I hit around 5500rpm his acceleration stoped and I think i would have started pulling if we didn't have to brake due to traffic.

A RB20DET with a R33 turbo hits full boost roughly around 3500rpm in normal every day driving. As does the R32 Turbo hit full boost around 3000rpm in every day driving.

[lowlux]

the reason my car ran lean the last dynoe run i had was because they pulled out the vacumn line to fuel reg therefore it leaned out up top,i havnt actually put it back on the dyno yet,i might actually do it next week sometime,but usualy on the dyno the car runs very rich like 9.8 to 1 but it usually hovers around the 10.1 mark which is just tooooo much fuel. Oh and the chip im using is 1 that came with the car from japan but Dr Drift (sam) can tune it easily now and he can do all rb20's so i suggest u ask him about chips

[Cubes]

I may have to take a trip over to Melbourne with the new motor to get the ECU tuned to suit.

Tilbrooks no longer do chips as Martin no longer works there.

I am considering the new microtech but I really don't want to spend the money.. It all adds up rather quickly.

[rb20-calais]

my mate has a rb20 in a 180sx... he is very happy with it

evan

[Cool Hand Luke]

Joel, the way i view different engines is percentage of revs. People say the holden v6 is torquey engine and has a good spread of power, but max torque is around 2300rpm which is almost exactly 50% of the way to the redline. The RB20 makes max torque at 3200rpm and revs to 8000, and has a usable powerband of around 4000rpm (thats what i would call a good spread of power)

With your drag with the SR, your not really comparing fairly. He was probably right in the fat part of his power band, but only had a few thousand rpm to go till his rev limit (even tho you guys might have both been at at say 3500rpm).

Although i have never driven in any really quick SR's, they have quite peaky powerband and dont rev like the RB's. You just have to listen to a mild SR, when it starts making good power he has to shift only a few secs later. While with the rb, albiet might make power later in the rev range, still has at least 4000rpm more to go before you need to shift.

my mate has a rb20 in a 180sx... he is very happy with it  

Agreed. Even tho my car has some fairly nice power roobbing problems and wont rev over 5500rpm, i could still beat other gts-t's with similar mods . I think standard they run 13.9's, i havent taken my car to the drags yet as there wouldnt be much point, but i have a FMIC, turbo back exhaust, pod filter, bleed valve etc so it should be good for mid 13's which isnt bad for a 180 . Just gotta get a 2530 + ECU!

[Cubes]

If you are going to mate the RB20 with a 2530 well then really you can't beat the RB for that sort of power level ...

You are right though the SR was most probably in the peak of his power band.. Just like the RB is at 60km/h in second gear..

[J.B.E]

Originally posted by Cool Hand Luke

from what i remember, mine has a black top.. I also have a VL turbo fuel pump but are going to upgrade to a  bosch 500hp with surge tank. I just wanted a cheap oe turbo upgrade to keep my happy till i get enough money for a real turbo. To change to a VG30 or RB25 turbo it will only cost a few hundred $ after i sell mine and from what ive determined its going to cost anywhere from $1800-2200 for a hi-flow on mine, or i could buy a gt2530 for $2400-3000 and sell mine, so i know which one im going to do. I just annoys me to have an engine that has a 7500rpm rev limit and only makes power till around 6000 .

Also does anyone know of a website or a thread where it had how a bunch of different turbos performed on an RB20? It had quite a few and what each ones overall performance, and lag was which would be pretty useful to me at the moment

If your looking for a little more power for little money Kelford camtech in NZ hav a pair of cams that will run on the stock computer and claim to give up to 25% increase ova standard which also might help with your top end power, there around $400 NZ