[bradsm87]

Sorry if you've already seen me ask the same question elsewhere. I'm really bad at making decisions and still undecided on going for a custom Hexon turbo that's smaller than "Stage 2" turbos or just going for off-the-shelf "Stage 2" turbos.

What I like about stock turbos that I'm a little worried about losing or partially losing when running bigger turbos:

- Chucking it back one gear only to 5th on the highway and pulling HARD effortlessly from 2500rpm for overtaking.

- Near-zero turbo lag at any RPM when snapping the throttle open any time from 2500rpm.

Has anyone got any honest before/after summaries of low RPM performance? I've heard too many "I'm running Stage 2 turbos and have zero lag" stories. The placebo effect really hits hard when $$$ have been spent. That's just physically impossible and not helpful.

Thanks in advance!

[tawfeeqh]

From all the reviews I have read about the Hexon rr600 it seems the low down responsiveness stays as per stock or even pulls slighty harder. These use the 15T compressor wheel as oppose to the 19T the rr700s have, which probably have a bit more lag compared to the rr600s. If I had my rr600s I would have definately been able to provide you with some honest feedback but I still haven't received yet. In Aus from what I know the only two cars with these rr600 stage 2 turbos are @nmE335 and bmwheath

I have spoken to nme335 and he reckons it is still very responsive and pulls hard, but maybe one of the guys above can chime in

Also dont know how the hexon stage 2 turbos compare against the rb and vtt equivelents for low down responsiveness

[bradsm87]

I'm open to opinions regarding RB, VTT Stg2 and Hexon RR600 as they're all pretty much the same in terms of wheel sizes used. There are definitely measurable losses below 3000rpm with any of these and can be seen on logs but logs still don't help you feel what the difference is like in actual driving.

The custom turbos I'm considering would be with 14T compressors and 44mm ind/37mm exd turbines, a touch smaller than RR550 ones. 14T compressors flow 38% more than stock in their correct housings, so even in stock N54 housings, they'll easy flow around 30% more than stock.

I think people having spent all that money try to tell themselves that it spools like stock and they probably even believe it because they may not have a solid memory of what stock is like but physics says otherwise. If that was the case, BMW would have just used that size turbo from factory.

[Socket]

TBH the revs climb so quickly that any low revs performance is the difference between fractions of a second. Any of the aftermarket turbos will provide a kick in the pants over stockies. If there is any lag in spool up its not worth worrying about IMO as you quickly get use to it

[Brule]

The bigger turbod may reach x psi 300-500rpm slower but real world driveability and instant torque is still there.

I've had stock,old school rbs and rb stealths.
Its not like your sitting waiting for the car to go these turbos are still tiny.

The only difference you feel real word Is a much wider power band when going to rbs. Bottom is the same, going from jb4- wedge improved spool the most. I'm talking improvement over stock turbos with jb4 tune.

People are saying there's no lag cause it does not feel like there is.

from rbs to rb stealths low end feels exactly the same and the midrange is the same but 5k rpm+ it has more power.

Don't look to much into it.
They will feel the same low end.

Even tonys gcs are spooling at crazy low rpms

[Socket]

Originally Posted by Brule

The bigger turbod may reach x psi 300-500rpm slower but real world driveability and instant torque is still there.

I've had stock,old school rbs and rb stealths.
Its not like your sitting waiting for the car to go these turbos are still tiny.

The only difference you feel real word Is a much wider power band when going to rbs. Bottom is the same, going from jb4- wedge improved spool the most. I'm talking improvement over stock turbos with jb4 tune.

People are saying there's no lag cause it does not feel like there is.

from rbs to rb stealths low end feels exactly the same and the midrange is the same but 5k rpm+ it has more power.

Don't look to much into it.
They will feel the same low end
Even tonys gcs are spooling at crazy low rpms

+1.

[Flex68]

Has anyone high flowed oem turbos ???

[bradsm87]

Originally Posted by Flex68

Has anyone high flowed oem turbos ???

Depends what you mean by high flowed. By most definitions, the upgraded turbos we buy are exactly that.

[_ink]

Originally Posted by bradsm87

I think people having spent all that money try to tell themselves that it spools like stock and they probably even believe it because they may not have a solid memory of what stock is like but physics says otherwise. If that was the case, BMW would have just used that size turbo from factory.

Hey Brad,

haha, you can't seriously believe that?! BMW were already consumed by fear that they had made a N54 monster that surpassed the M3, so they detuned it to keep it in check. They also need to build to power levels so the engine can reliably operate the internal engine components (not forged) and to last to warranty period and beyond.

When i was upgrading to RB's, this was also the biggest factor i was considering - But at the end of the day, they are still a puny upgrade in wheel size, unlike a big single upgrade.

There's also spool mode that you can now utilise on hybrids (which you may already know), I hadn't needed to use it until i changed to my custom 3.5" exhaust which resulted in torque loss down low (not such a bad thing for my DCT).

I would still agree with you that there is a slight loss, however the gains are everywhere else! And that trade off was good enough for me. I mean, how often are you in <2500rpms? A simple gear change will put you in the hybrid power band instantly! (unless you're in 1st gear of course )

Here's my most recent 3rd gear pull if you are interested:

http://datazap.me/u/ink/v14-log?log=0&data=1-4

[bradsm87]

Thanks for the replies guys.

_ink , That must absolutely haul ass! So much boost AND timing. Is that with 100% E85? (edit: just read E60 in another thread) With that kinda power and awesome DCT gear changes, it really doesn't get much better than that!

[Flex68]

Noon question are the n54 oem turbos bush bearing or ball bearing ?

[_ink]

Originally Posted by bradsm87

Thanks for the replies guys.

_ink , That must absolutely haul ass! So much boost AND timing. Is that with 100% E85? (edit: just read E60 in another thread) With that kinda power and awesome DCT gear changes, it really doesn't get much better than that!

Thanks mate

It's hauling pretty well, and yours will too!! I'm back to e50 now, cos stg2 LPFP says no to e60.

Pull the trigger Brad! You won't regret it.

[bradsm87]

Originally Posted by Flex68

Noon question are the n54 oem turbos bush bearing or ball bearing ?

Bush

[_ink]

Originally Posted by Flex68

Noon question are the n54 oem turbos bush bearing or ball bearing ?

Journals

[335i-boy]

I have the same concerns as bradsm87 regarding going upgraded turbos. I also have asked the same question but have not received a decent answer. Even so when querieng VTT's stage 1's. A big cash layout certainly does seem to induce some placebo here.

I was told a few years ago that RB's will have a delayed spool of 500rpm. I feel that with an auto that's a whole heap. This car is my daily driver. What makes the car fun for me is not having to think what rpm I'm in. I just put my foot down and I'm outta there, with kick down or not. Now if RR600's have the same spool as oem's with a little tuning and keep the power on for longer, then that is ideal.

[Flex68]

My biggest concern is reliability of these hybrids . Not only forking out the cash for the turbos but all the hardware and labour to go with it and having the chance of they smoking or leaking warranty or not

[T1M]

Yeah, agreed, and I think turbo technology has come far enough that a larger single can outspool and outflow twins. It's been the case for years now on the RB26 GTR platform that singles surpass twins. You have one turbo, one wastegate, one exhaust, one boost solenoid, one heat source, one water and oil feed, one drain and water return, one intake, its so much simpler.

I'd like a custom 321 stainless manifold and a Borg Warner EFR 9180. I wouldn't even bother running E85, that on pump 98 would be me done.

Honestly I dislike the small stock turbo feel. Peak torque at 2950 is a PITA to manage in the wet, the turbos are always spooling, you can't just drive gently easily. Torque ramps up too fast, peaks too early and due to the tiny turbo hotsides choking falls from 3000rpm to redline, so the more you rev it the slower you feel you are accelerating. I hate that feeling. I like a linear build to say 4000-4500 peak torque, then a nice flat tabletop then drop to redline over the last 1000rpm or so as the hotside restriction and pressure delta across the turbine drops the engines VE. A normal high power turbo engine feel in other words. If I wanted a V8 feeling, I'd have bought an M3 not a 1M.

[vtl]

I've driven Socket 's car and it was nice to have the car pull to redline vs peaking early and dying off. It doesn't feel like it pulls much stronger than the stock peak torque, but it never dies off and holds it to redline.

Can't really comment too much on the responsiveness though. I tried to test the response but since I drive a manual, the throttle maps are different and not that comparable. Felt a bit laggy to me but that could have been the auto box, the manual's throttle sensitivity is higher, even when you are driving in M or S mode in the 6AT.

[bradsm87]

Originally Posted by vtl

I've driven Socket 's car and it was nice to have the car pull to redline vs peaking early and dying off. It doesn't feel like it pulls much stronger than the stock peak torque, but it never dies off and holds it to redline.

Can't really comment too much on the responsiveness though. I tried to test the response but since I drive a manual, the throttle maps are different and not that comparable. Felt a bit laggy to me but that could have been the auto box, the manual's throttle sensitivity is higher, even when you are driving in M or S mode in the 6AT.

Different throttle maps from tuners can change the way lag is perceived too.

[DR-JEKL]

Originally Posted by _ink

Thanks mate

It's hauling pretty well, and yours will too!! I'm back to e50 now, cos stg2 LPFP says no to e60.

Pull the trigger Brad! You won't regret it.

Why would you stay with the stage 2 LPFP when you have PI dude and not upgrade to stage 3 so you can run 100% E85?

I must admit mixing E50 is dead easy and you get nice smooth cold starts and barely much difference in terms of fuel economy during regular driving

[JB4-335]

Originally Posted by DR-JEKL

Why would you stay with the stage 2 LPFP when you have PI dude and not upgrade to stage 3 so you can run 100% E85?

Cause he doesn't want to spend too much money on his car.

[bradsm87]

I think I'm just going to go for the customs. Somebody's gotta try em so it may as well be me. 14T wheels flow 40% more than stock and only 10% less than 15T wheels and the turbine size difference is similar too. This should be ideal for what I want, which is boost as early as possible and 19psi flat to redline on E17 ethanol mix (easy for the wife to mix at the bowser with 10L jerry can of ethanol) and make around 330kw at the wheels.