I'm debating on getting a bnr turbocharger. I have all the supporting fuel mods, ecu, and intercooler. The only thing I haven't gotten around to is a fuel pressure regulator, and of course tuning after the turbo is installed.

Anyways, I was trying to do some research on the pros and cons of a stock turbo with a bigger compressor side. Right now it fits my budget, so I'm probably still going to end up with a bnr, but there has to be some downside vs a complete turbocharger upgrade.

 

theres really no downside. bolts on, maintains stock manifold, cheaper, wastegates already done for you.

 

Hmm..downside..You will have extra money!,so the Wife will spend it on a Fur Lined Sink and Gas powered Turtle neck sweater..when you could have gotten car parts!

It's a good Bang for the Buck if the rest of your Mods are not really wild.You can stay within stock fitment and still get power.
Going to an aftermarket Turbo you look at the ECU,Fuel system,exhaust manifold,wastegate,downpipe, FMIC..etc etc..so it adds up.

 

Pros: Cheap, easy, warranty.
Cons: Based on the small OEM turbo, which does not have an optimal manifold, does not have a modern ball bearing cartridge, and requires clipping for higher output. This results in more lag, slower response, and less efficiency vs. a larger, modern, properly sized turbo.

 

only downside is internal wastegate. the factory manifold itself flows plenty, wastegate design is really poor though

 

My opinion of the BNR hybrids has changed drastically over the last few months of actually dealing with a car running a stage 3 from a tuning and build (not just a quick few fun WOT runs) perspective.

The pro is that they are relatively inexpensive, bolt onto the stock manifold, bolt up to the stock exhaust, and (mostly) use the stock plumbing.

The cons are that in my experience, boost level issues are going to be a massive headache. And they aren't quite "bolt on" as promised (is anything though?).

First, the "bolt on" aspect is not quite true both the turbo and lower intake manifold required some clearance grinding. Not the biggest deal in the world, but when the turbo advantage is "bolt on", then making it less bolt on takes away some of the advantage.

But by far, the biggest headache has been achieving the desired boost level. The car is nothing special, just a S4 TII, street port, MS3x. It was a bit of a mystery at first that the boost controller was not able to raise boost. All tested fine with shop air as the boost source. We could easily control the wastegate through the MS3X boost duty table and DIYAutoTune solenoid. Same config I've used many times before. Yet on the road, boost always peaked at about 8 PSI and then fell rapidly. Even with the wastegate line totally disconnected!

Some calls to Brian confirmed that he ships the wastegates with a 6 PSI spring! What the hell?! So sell a turbo efficient around 15 PSI and ship it with a 6 PSI wastegate?! High exhaust backpressure (remember, stock turbine and manifold) meant that the wastegate was being pushed open and with such a wussy spring, there was no hope of keeping it closed. His suggested solution was to clip external spring to the wastegate arm? Seriously?! I'd be ashamed if those words were coming out of my mouth.

But surly enough, an external spring worked and we had 15 PSI on the boost controller. Car pulled very well indeed and very little boost bleed off at redline (maybe down to 13 PSI). These turbos are a midrange turbo, not for high airflows.

Brian promised to send a wastegate actuator with a higher spring rate. Two weeks went by and he delayed again and again. Finally a new wastegate actuator arrived. I had suggested to my friend we just buy a good one at ATP Turbo but he wanted Brian to make good (understandable).

The "13 PSI" actuator was installed last weekend and we went out for tuning. And made about 10 PSI with the boost duty at 100%, bleeding down to around 6 -7 PSI at redline. WTF?! So either the actuator supplied was not 13 PSI (though based on shop air it had a MUCH stronger spring than the original) or the pre-turbine pressures are huge. Probably a mixture of both. Unfortunately the desire to get the car on the road means that the external spring will be reinstalled so it can be tuned and driven. Then maybe down the road a double nipple actuator will be purchased.

This experience however has forever soured me on the BNR hybrids. I truly believe now that it is a simple issue of you get what you pay for in price and convenience when it comes to these turbos. If sticking a heavy external spring on your wastegate arm doesn't bother you, or the fact you may have to hunt around for a more suitable actuator, or go through the pain in the butt of converting to external wastegate, then it may be an option compared to the high cost of a full turbo upgrade. Me personally, I would not bother with the hassle.

 

great post Aaron

 

Our BNR stage 1 wouldnt hold more than 6 and Bryan recommended the helper spring. Like Aaron it worked though we are only doing 12.

One other advantage of the BNR is that it looks stock; at least at the lower stages. Since you live in the People's Ecotopian Republic of California , passing the inspection could be a concern. But if you're really a subversive gross polluter, then you may have ways of getting around that with tubular manifolds and anodized w/gs.

 

Pros: all the above

con and will always be a con: shitty wastegate from the factory, and you have to keep adding band aids to to work around it.

 

Thanks for the thorough explination! I was always curious about fitment issues. My current turbo is a factory turbo with a to4 compressor side, but I ended up griding the housing a bit to fit. I was wondering how bnr was able to fit without grinding. Now I know you do need to grind. My turbo is burning oil, and was thinking of trying their stage 3 and hoping I won't need to use the 1 year warranty.

 

I removed the bolts from my unused stage 2 comp housing to clock it a little and grind some. I noticed the bolts were too short and the threads had started to pull out of comp housing. Had to chase all bolt holes with tap and added longer bolts. Not good! The waste gate porting gets really close to one bolt hole. Scary close , worried about future cracking in that area. Next time I'll get a local shop to mod my turbos.

 

Pro: bolt on.
Con: bolt on.



I have a knightsports hybrid. I had to have the waste gate ported. It fits with no issues. I hope I don't run into waste gate actuator issues like Aaron said.

 

i too had to run a helper spring, unclipped stage 4

 

You forgot the $300 pair of socks.

 

I think a S5 ('89-91) based BNR Stage II is a really good turbo for 250-300RWHP.

It is factory true divided turbo housing with dual internal waste gates and the Stage II compressor and stock exhaust wheel aren't such a mismatch in size that you get into the issues with boost control.

I don't think you can find a better engineered 250-300RWHP turbo/manifold in the aftermarket without going custom (something like a HKS divided FD manifold with a T3 flanged GT30R with smaller compressor back plate and compressor cover machined to fit).

I wouldn't stick a S4 based turbo on anything by choice.

 

Well came across this thread. Trying to get my car to pass emissions legally. I have a fully built TO4B 60-1 turbo and can not bear to think of driving a stock powered FC. So I bought a new harness and have a brand new stock Cat converter to install. I was going to try to run everything stock emissions wise with a P1000 ECU with a patch harness or Rtek with my big turbo or a Stage 4 BNR. I've read a few times of boost control issue with BNR. Now I'm not so sure what to do.

I don't think there is a proper turbo manifold out there that fits a single turbo with full emissions including air pump.

 

But will a stage 2 work with a factory sized tid?

Rotary > Pistons

 

Not to thread jack and bitch about BNR but... this was an email I sent to BNR about my turbo. I feel this is not the response I was looking for...



To whom it may concern,

I purchased a stage 4 turbo for an FC rx7 from a forum and he failed to tell me that most(if not all) the bolts/studs are loose/mixmatched... I was wondering how much you might charge to "rebuild" it.

Thanks,
Matt


Bryan Nickell


11:43 PM (1 hour ago)

Hi Matt.

Tighten them up and run it lol. If you have problems give me a call and we'll discuss servicing.

Bryan Nickell
Owner of BNR Supercars LLC
(205)640-1193
bnrsupercars.com
__________________

 

Don't be a bitch, tight the bolts and run it, whats wrong with that?

 

who the **** are you? lol I wasn't looking for "tighten them" I was asking about a look-through/possible rebuild. but thanks for your input as well... about as useful as his.

 

You are asking a guy who is busy rebuilding turbos to go through your turbo and source new hardware for it and make sure its all tight.

Yes... he could do it, but do you want to pay his hourly rate for him to go to the hardware store for the standard hardware and source new parts from Mazda for the specialty hardware.

If you can put the turbo on the car you should be able to source the hardware and tighten it on the turbo as well.

If you are having a mechanic do the work, pay their $100/hour or whatever for them to source the hardware and tighten bolts for you. Standard mechanics rate is going to be cheaper than a specialty mechanic like a turbo rebuilder.

If you are asking him to take it apart and check if it needs a rebuild, its going to cost what a rebuild does since he has to take it apart and put it back together.

You showed us the correspondence and his reply seems reasonable to me as well.

Does the exhaust wheel have a bunch of scorched oil and carbon on it? Do the wheels rub on the housings if you press them to one side and rotate the? Does either wheel have bent fins or obvious damage? If none of these then 99% chance it doesn't need a rebuild.

 

But will a stage 2 work with a factory sized tid?

From what I remember the stock TID is a 2 piece affair with the takeoffs for BOV and Evaporative emissions on the upper part.

It should be fairly easy to make a new lower part if the Stage II turbo housing inlet is larger diameter and it will still look/function as stock to pass visual.

 

my 2c.. i dont live or work in the US and have no affiliation with BNR

i do however build my own hybrids ,, have done for many years,, have seen most evolutions

firstly/./ the wastegate can is a diaphragm weighted against a spring tension
.. it is not practical to open up the can and add a new spring

keeping the 7 psi rated stock can and trying to control it with a boost bleed
( even with electronic solenoid control )
is always going to end up at some point where delivery down the pipe to the can will defeat the amount being bled and you end up with a bell shaped boost curve as it falls back to the spring rating
you have to introduce smaller and smaller restriction into that pipe to bring control back to the bleed valve for higher boosts and the overshoot and bell shape will just get more peaked,,
this just a function of a boost bleed

.. physics.. sorry ..


adding a helper spring is in no way dodgy.. isnt cheating anything .. and is in fact the most correct mechanical correction for the task
its also bloody easy to do// i have one on mine.. have done for years . and i have the HKS adjustable arm can

the other method.. is the cans with double diaphragm ,, where one works against the other to assist with the spring .. using the bled away air .. just like external gate setups

still.. it is no perfect system,, and is not superior to simply having the spring tension closer to your set-point

FYI.. i hold 15 psi as my setpoint and bleed back to 13psi only under high revs .. haltech closed loop controller and solenoid

and the turbo uses stage 2 t3 turbine,, and U trim on the front,, and so does not suffer from a massive missmatch of flow potential between front and rear,, so no excessive pressure ratios,, and no stress on a 270 thrust bearing,, and its reverse threaded nut,, so no nasty unwinds either

"highflow' is such a wide term that encompasses well engineered examples with some that couple 60-1 fronts to stock turbines,, that spike,, thrust and wear rapidly and unwind compressor nuts

and so some of these must be coupled to external gates,, and frankly,, why didnt you go for the full t4 or equiv in that boat?

while the well thought out examples .. have turbine flow that suits the compressor selected use a B or a stock cover that fits against the inlet manifold
and just work well and fit straight up without hassle and thus ARE good alternatives

especially when you require stock look , use a single plate clutch ,, a un-dowelled or stock block and only want to upgrade the secondary injectors and tune .. and thus dont want to be forced down a constant upgrade path

PS.. im using ta34 ( stage 2 t3 ) turbine and U trim t04b compressor,, steel 270.. nothing fancy here.. just well matched flow potentials when under rotary exhaust temps .. . with helper spring

im sure there is BNRs in similar specs

 

That's hilarious!...lol

 

LOL, that's sig-worthy.