Fun street RB25

[Rand0b]

Hi all was looking for some real world input on a badass street rb25. the  biggest thing is that I have never owned an RB25 before. Will be rb25 in z32

will have supporting mods needed

FFP, id1300 , built bottom end

Will I NEED cams? I don’t think so since it’s not a full effort track dedicated setup. I think they would assist but not 100% necessary.  wanting drop in with no head clearancing needed was thinking tomei poncams IF needed

 

I have been Looking at rb25 and rb26 dyno sheets to see what a good balance is for HP goals vs turbo spool. Would love to hit 6-7XX number on the dyno.  using race fuel /e85 But willing to be realistic on dyno number. I looking at 25 dyno graphs gives idea on power/spool However does not give what drivability is like. And I know pump gas power would be lower power overall I was thinking of a turbo that would be almost maxed out on the dyno on e85 so then it would still be a good turbo for street if not on e85, (e30,e50, ect)

so i don’t know what size turbo would make a RB laggy or not street friendly.

I know there is a tradeoff in spool vs power, but For a street RB with spool /response

20psi by ~4k  GREAT!!

20psi by ~4.5k  Good

20psi by ~5k  ok…

20psi by ~5.5k Laggy

So I guess from you experience what would your comments be?

Are my dyno power goals out of reach for a GREAT!! – Good street car? 

Would you adjust the psi vs rpm category for the GREAT!! Good ok Laggy??

Everyone seems to like the Precision 6262 and people have made some good power on e85 in the rb25 dyno / precision thread.  I seen a lot of people praise the power / response for the 6262

SilverECR33 had a 6262 BB and made 500hp on 24psi e85 so a 6062 gen2 should be able to make more with better response 

R33ryan had a 6062 BB and made 710 at 29psi e85

I have heard a lot of good things from the Hypergear turbos also

ATR43SS3-Pro T3x 900HP made 455rwkws @ 22psi, E85 fuel, Rb25det

Maybe the 6266 but it needs to have a two scroll manifold but then have read others say it’s to big a turbo

I think these fall right in the ballpark of what I would need for a Badass Street Car and get close to my Power goal

Thinking the 6062  , or the ATR43SS3-PRO?

thanks !

 

 

[Duncan]

The main thing I can say is setting your goals by dyno sheet is likely to be disappointing (too expensive and not nice to drive).

Anything more than 300rkww will be wheelspin city in 1st and 2nd. For genuine fast street fun I would stay under 350rwkw and put the best tyres you can on it; this will also cost about half as much as 450+ like you are talking above.

 

[GTSBoy]

What he sed ^^.

There is no way that a 700HP RB25 is a "fun street" engine. Any more than 300rwkW is almost completely wasted on the road. Unless your definition of "fun" means simply destroying tyres.

[joshuaho96]

I would pick a small bolt-on turbo and set my targets much, much lower. RBs are annoying to build for big power, a guy I know has gone single GTX3576R gen 2 on his RB26 and even with a whole laundry list of oil control modifications he is still filling his catch can on the track.

[Kinkstaah]

Yep. I was excited by this thread and "fun street RB" until you said 6-700 anythings...

For your intended number, EFR 9180? lol.

My actual choice for an actual street/fun RB is closer to something like an EFR7163.

Borg Warner EFR's are still unmatched for part throttle stuff. They are just so lovely to drive in non 100% WOT scenarios, like almost 100% of the time a car is driving on anything that is not a race track or drag strip or dyno.

[Rand0b]

On 5/19/2022 at 7:05 PM, Duncan said:

The main thing I can say is setting your goals by dyno sheet is likely to be disappointing (too expensive and not nice to drive).

Anything more than 300rkww will be wheelspin city in 1st and 2nd. For genuine fast street fun I would stay under 350rwkw and put the best tyres you can on it; this will also cost about half as much as 450+ like you are talking above.

 

 

On 5/19/2022 at 7:54 PM, GTSBoy said:

What he sed ^^.

There is no way that a 700HP RB25 is a "fun street" engine. Any more than 300rwkW is almost completely wasted on the road. Unless your definition of "fun" means simply destroying tyres.

That’s what I was thinking I may need to rollback a bit. I plan on having a good tire with some meat on back ~275 /40

[Rand0b]

On 5/19/2022 at 8:29 PM, Kinkstaah said:

Yep. I was excited by this thread and "fun street RB" until you said 6-700 anythings...

For your intended number, EFR 9180? lol.

My actual choice for an actual street/fun RB is closer to something like an EFR7163.

Borg Warner EFR's are still unmatched for part throttle stuff. They are just so lovely to drive in non 100% WOT scenarios, like almost 100% of the time a car is driving on anything that is not a race track or drag strip or dyno.

I was looking at this turbo and the feature set is nice. just the bulkyness of the compressor housing / features isn’t clean for me. Yes I am leaning a bit more for looks in this case

[Kinkstaah]

On 5/20/2022 at 10:40 AM, Rand0b said:

I was looking at this turbo and the feature set is nice. just the bulkyness of the compressor housing / features isn’t clean for me. Yes I am leaning a bit more for looks in this case

The EFR7163 is smaller (and is in the 300-350kw range). I had a 7670 on a 2.8 Neo and it was fkin awesome. Blew everything out of the water.

It's a neat turbo installed, given it has a built in boost solenoid and BOV as well. Given it's relatively small size it'd be damn easy to mount.

If you wanted the car to look stock (i.e low mount) there is the Garrett G25 range, and there's probably logic in a G25/G30 550-600 region which would also be the bomb. (but I still prefer EFR)

I would throw the FFP in the bin (or sell it), it will do nothing for you but create potential issues you don't need to have. Cars that look good with the bonnet up are one thing. Cars that drive good with the bonnet down are another. I know which one I choose if I have to decide between them, so my answers are biased that way.

[Rand0b]

On 5/19/2022 at 8:45 PM, Kinkstaah said:

The EFR7163 is smaller (and is in the 300-350kw range). I had a 7670 on a 2.8 Neo and it was fkin awesome. Blew everything out of the water.

It's a neat turbo installed, given it has a built in boost solenoid and BOV as well. Given it's relatively small size it'd be damn easy to mount.

If you wanted the car to look stock (i.e low mount) there is the Garrett G25 range, and there's probably logic in a G25/G30 550-600 region which would also be the bomb. (but I still prefer EFR)

I would throw the FFP in the bin (or sell it), it will do nothing for you but create potential issues you don't need to have. Cars that look good with the bonnet up are one thing. Cars that drive good with the bonnet down are another. I know which one I choose if I have to decide between them, so my answers are biased that way.

Rb will be in a z32 chassis and hood clearance will be tight that’s why a ffp is needed, gotta have a top mount  manifold to show off the turbo

I will try my best to get a plazman top half but who knows if it will fit

Edited May 20, 2022 by Rand0b

[joshuaho96]

On 5/19/2022 at 5:54 PM, Rand0b said:

Rb will be in a z32 chassis and hood clearance will be tight that’s why a ffp is needed, gotta have a top mount  manifold to show off the turbo

I will try my best to get a plazman top half but who knows if it will fit

If the goal is street use I recommend using the longest runner manifold you can find. Look at a factory VG30DETT manifold, it's incredibly long compared to an RB26 to help it make good torque down low.

[Rand0b]

I’m also confused because people are saying the RBs don’t build boost well but  I see everyone recommending 1.0x for turbine a/r

Edited May 20, 2022 by Rand0b

[joshuaho96]

On 5/19/2022 at 8:04 PM, Rand0b said:

I’m also confused because people are saying the RBs don’t build boost well but  I see everyone recommending 1.0x for turbine a/r

An EFR7163 would be 0.80 a/r for twin scroll, 0.85 for single scroll.

[GTSBoy]

And the EFR7163 is a hybrid flow turbine too, so, not quite apples and apples when comparing to other turbos A/Rs anyway.

[WR33KD]

I run just shy on 400kw on the street and it’s very easy to drive change gear at 3500 and it’s normal car, alright on fuel and does what it needs to do. Running 265s semis on the back help lots. Let them warm up and you get a little wheel spin in 1st and 2nd but nothing to cry about. 
Having full boost down low in the revs will put the motor under strain. You will still make boost lower down just not max boost until 4500-5000rpm. If you make max boost at 3500-4000 that’s going to run out at 8000-8500 and the load that low will brake something. 
Everyone will have different story’s about this that and the next thing so it’s up to you what you pick and choose 

[The Bogan]

Budget for a gearbox that will hold that power if you plan on using that power 

[Rand0b]

On 5/20/2022 at 2:23 AM, mlr said:

Budget for a gearbox that will hold that power if you plan on using that power 

Rb bellhousing on z32 jdm trans has been reliable to ~700whp 

[GTSBoy]

On 5/20/2022 at 6:24 PM, Rand0b said:

z32 jdm trans

And the difference between that box and the internals of the RB25DET box is what?

[Rand0b]

On 5/20/2022 at 6:50 AM, GTSBoy said:

And the difference between that box and the internals of the RB25DET box is what?

has the same internals except the 300zx 98 spec has stronger synchros, fork and redesigned gears. This is the go to for the 300zx people making ~700whp

[Rand0b]

On 5/20/2022 at 1:28 AM, WR33KD said:

I run just shy on 400kw on the street and it’s very easy to drive change gear at 3500 and it’s normal car, alright on fuel and does what it needs to do. Running 265s semis on the back help lots. Let them warm up and you get a little wheel spin in 1st and 2nd but nothing to cry about. 
Having full boost down low in the revs will put the motor under strain. You will still make boost lower down just not max boost until 4500-5000rpm. If you make max boost at 3500-4000 that’s going to run out at 8000-8500 and the load that low will brake something. 
Everyone will have different story’s about this that and the next thing so it’s up to you what you pick and choose 

Agreed, that’s why I was asking on power delivery. If a 3076 is going to hit like a light switch 20psi ~4000rpm

i would think a slightly bigger turbo that maybe would start spooling 3500 and then gradually lean into 20 psi around 5k would be better power delivery?

just don’t kno what that turbo is

[Kinkstaah]

Borg Warner EFR's are the best at that. It is their entire thing. No turbo comes on that slowly (under full throttle) but you could set a boost controller to do that if you wanted to.

Boost by gear and artificial traction control by tapering boost on slowly is a thing that people do, but then you have a scenario where you either make the boost come on slow enough to keep grip in 4th (and thus 1-2-3 is wheelspin still) or you set your boost ramp for traction for example in 2nd, but you're leaving power on the table in higher gears.

The simplest answer is a new Garrett G series. Buying a G25-660 on a 2.5 would be great and still not annihilate gearboxes, overcome commonly available tyres, create clutches that are too annoying to drive, and is physically compact so you get plenty of space to run lines to and from it.