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Rb25 det turbo recommendations

Erra66
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Erra66 Newbie

Erra66

Posted
Posted

Hi guys,

just wanted some recommendations on turbo sizing for application as im not quite sure which one to pick!

RB25.6 Forged motor, crg manifold should i go t3 or vband inlet? looking at gtx3076r .82 rear or 3582r .82 rear 

would the 3076 be to small for 580-600whp as im looking for the least amount of lag possible 

Cheers!

 

 

 

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https://www.sau.com.au/forums/topic/477580-rb25-det-turbo-recommendations/
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KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted
11 hours ago, Erra66 said:

Hi guys,

just wanted some recommendations on turbo sizing for application as im not quite sure which one to pick!

RB25.6 Forged motor, crg manifold should i go t3 or vband inlet? looking at gtx3076r .82 rear or 3582r .82 rear 

would the 3076 be to small for 580-600whp as im looking for the least amount of lag possible 

Cheers!

 

 

 

450 kw at the wheels is very ambitious for an RB25. You will need a massive turbo (neither of the ones you have suggested)  and it will be massively laggy. Have a look at the RB25 upgrade thread in the forced induction section  to see what others have done - and start at the end for some more modern ideas.

WR33KD Collaborator

WR33KD

Posted
Posted

I’m running 450kw in a rb25 and it’s not really all about how big yo turbo is but more about how your cams are matched to your turbo.
To many people but a big arse snail on and wind the boost up and make no power, get a nice cam, 264/272 and it will help you make boost sooner and better

Ben C34 Grand Master

Ben C34

Posted
Posted
8 minutes ago, WR33KD said:

I’m running 450kw in a rb25 and it’s not really all about how big yo turbo is but more about how your cams are matched to your turbo.
To many people but a big arse snail on and wind the boost up and make no power, get a nice cam, 264/272 and it will help you make boost sooner and better

To put that post in perspective, what turbo are you running and when is full boost?

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted
2 hours ago, WR33KD said:

I’m running 450kw in a rb25 and it’s not really all about how big yo turbo is but more about how your cams are matched to your turbo.
To many people but a big arse snail on and wind the boost up and make no power, get a nice cam, 264/272 and it will help you make boost sooner and better

 

2 hours ago, Ben C34 said:

To put that post in perspective, what turbo are you running and when is full boost?

Was just about to ask the same...what turbo and have you got a dyno chart to show us?

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Longer duration cams also doesn't magically "help you make boost sooner and better"
Cam duration actually changes the torque characteristics of the motor.

I would get a Sinco manifold over the CRG one and get a proper twin scroll manifold, with a proper twin scroll rear housing on your turbo.

WR33KD Collaborator

WR33KD

Posted
Posted

Don’t mind I don’t no what I am talking about, I just have a car the proves what I said is right. Changing the duration of lift helps hugely with boost as you increase air flow and with cam gears can dial it in.
Go and wack a huge turbo on your 25 and tell us how it makes boost.

I’ll wait for your reply as it will take as long as for boost to load

IMG_1001.jpg

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Ben C34 Grand Master

Ben C34

Posted
Posted

That's a sweet result. That's alot of hesitation when it comes to cams, as you can always just run more boost to get more power, however the extra lift has to be better.

If you increased duration and left lift alone you would really only move the power higher I to the rev range, however adding lift brings more all round. Coupled with adjusting cam timing the results speak, but pretty much no one has changed just the cams for a clear back   to back comparison.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Your chart is very impressive!  I think its more down to the turbo than the cams. My engine just had the stock R33 cams and a Garrett 3540 but built boost a little more quickly than yours but from 4000 on yours just takes off. I suspect that with different cams you would make boost earlier  and you have power to burn at the top end.

(Full disclosure - mines on an RB30/25 with a Sinco manifold)

2013.11.21 Boost curve 001.jpg

2013.11.21 Power & Torque 001.jpg

Murray_Calavera Mentor

Murray_Calavera

Posted
Posted
1 hour ago, WR33KD said:

Don’t mind I don’t no what I am talking about, I just have a car the proves what I said is right. Changing the duration of lift helps hugely with boost as you increase air flow and with cam gears can dial it in.
Go and wack a huge turbo on your 25 and tell us how it makes boost.

I’ll wait for your reply as it will take as long as for boost to load

IMG_1001.jpg

Have you taken it down the 1/4 mile? I would be very keen to see the trap speed 

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted
1 hour ago, WR33KD said:

I’ll wait for your reply as it will take as long as for boost to load


Not sure what's with your attitude but I've got a fairly large turbo on a 2.5L motor and I'm making 1.3bar at 4300rpm and 1bar at 4000rpm. Mind you these were runs in 2nd gear down a road, once I've got time to tune the car it will be coming on much earlier when it's loaded up in 4th gear on the dyno.

 

WR33KD Collaborator

WR33KD

Posted
Posted

Also if you running a s2 25det your redline will be stuck at 7500 due to the hydro lifters, I got my plugged to increase redline to 8500.

1/4 mile times are only 12.6 but at 126mph, haven’t had much seat time work.

Before the car got built we did stick it on the dyno and loaded it up and it made 363wkw on the same 22psi.

Once you hit the about 500hp mark your gearbox and diff become a real problem. I’m 4 bigboxs and 3 diffs before I went nismo and ppg

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