hey guys,
im buying a new turbo for my car and i want to understand and get a better idea of what im buying. I found a new Borg Warner s362 for $800 with an "extended tip" and a .88 turbine A/R. the end that attaches to the manifold isnt devided (im not sure what the term for that is) but my mechanic says its better for rotaries if it is devided. he also mentioned that a .88 A/R is kinda small for rotaries and recommends it to be around 1.15 A/R.

he buys his borg warner turbos strait from bullseye power and mentions they work on the turbos to be a better match for rotary cars and that it reflects the price ($1200-$1400) for the same turbo but has a bigger A/R and divided where the turbo meets the manifold.

can someone help me better understand the differences and if it would just be better to go with the one that is modified by bullseye? is it worth the extra 400-600 or should i just go with the company selling essentially the same turbo for 800 but not modified to the same specifications?

THANKS IN ADVANCE!!!

 

Divided housing/manifold > undivided housing/manifold. It's not a rotary thing; it's the same for any engine. By splitting the chambers in two, exhaust gas velocity is higher when there is low gas volume, which means the turbo will spool up quicker when you punch it.

Turbine housing A/R will define how the turbo behaves. A smaller housing will spool faster, but may have power taper off by redline. A larger housing will be more laggy, but flow better up top. It depends on the endine, it depends on what you want, and it depends on the turbo compressor/turbine wheels.

 

Just remember that if you Bought or buy another turbo,it doesn't end there.
You also have to buy a manifold,oil lines,Wastegate,and down pipe and so on,.
The Turbo won't be a plug and play unless it is a BNR type turbo( BNR makes Hybrids that just Hook up as stock,so to speak.)

 

thanks for the information guys. i did end up ordering the turbo last night and the specs for the borg warner s362 are: Compressor Wheel Ind. 63mm Extended Tip, Turbine Wheel 71mm, .88 Turbine A/R, Flows Up To 67lbs/Min, T4 Mounting Gasket and it is noted that "Turbine Housing V Band Outlet Can Be Machined Down To A Flat 4' Upon Reguest"... being that im not familiar with turbos, should i opt for that last part?? this is my first rotory and reliability is a big factor for me but im still looking to achieve 350 or <400 whp on 12lbs with this turbo. what are your thoughts on this turbo for my tII??

i understand that in buying this turbo i will be piecing together my own turbo kit. so far i will be going with this turbo and a GODSPEED front mount which leads me to my next question;

-can i use any t4 manifold for an fc or are there other things i need to factor in for fitment ect? how about down pipes? are there specific ones for different turbos?... any brand you guys would suggest?

-i assume things like the wastegate and bov's are universal? i also dont know much about these supporting mods but if i need both i plan on getting TiAL brand. i understand there are size differences for these and i assume depending on power i will need to purchase the correct size, spring, ect? ..so for my application, can anyone suggest any size/combination of the two?

...thanks for the help. this is the first turbo kit im putting together and im willing and trying to understand more about it. my mechanic will be taking care of me with the fuel system which will consist of KGParts and he will also be tunning it on a microtech lt10 along with koyo rad and black magic fan to cool it... other than the things i mentioned, are there any major supporting mods im over looking or should concider?

again, THANKS IN ADVANCE

 

I think you'll be closer to 325 RWHP on that turbo at 12 PSI, but as I'm not familiar with BW turbos I'm just guessing based on the specs you posted.

I'm not sure what machining the v-band to a "flat 4" means at all, but I suspect you don't want to do it. A standard v-band at the turbine outlet will make it easy to fab up a downpipe with a matching v-band.

You would need to use a T4 manifold designed to fit the TII (or in some cases, the FD) but I can't guarantee you wouldn't run into any fitment issues. Such is the case with mixing and matching parts. Avoid the cheap eBay style manifolds.

As with any non-kit based turbo upgrade, you will need to fabricate your own downpipe, as well as your own mid pipe and likely your own turbo (compressor) outlet pipe.

Any old BOV will do the job, frankly. Tial makes good ones.

Your wastegate will need to be at least 40MM in size. Additionally either you'll have to modify the turbo manifold to accept the style of wastegate you choose, or choose a wastegate to fit the manifold. Thankfully, many manifolds include a 4 bolt HKS style flange which is fairly common on wastegates. Plus, most wastegates come with a matching flange which can be welded onto the manifold. Tial is again a very good brand. The simplest way to set up your wastegate would be with a 12 PSI spring and just run the natural wastegate pressure for the beginning. Then when you decided to raise the boost, use a boost controller.

You'll need a clutch to support the new power level. Additionally you'll want appropriate gauges: boost gauge and a wideband at the least.

Why are you going with Microtech? Their ECUs are an ancient design, with ancient limited firmware and poor laptop software. For the same price you can get a Haltech Sprint RE which is an ECU designed in this decade. Or upgrade a little to the Platinum Sport 1000 with has more features. Seriously though, avoid Microtech unless you are building a track only car.

 

thanks for the response, aaron.. im shooting for 12psi cause i read the s5 motor is best under 14.5 psi. being my first turbo/rotory, i want to keep it at a relatively safe level. my mechanic is jim from jpr imports and im guessing he suggested microtech cause hes used to tuning with them? thats my guess.

are there differences in turbo down pipes and an exhaust down pipe? i know you mention i would most likely have to fab one up if im putting a kit together myself but what if im buying racing beat's full rev 2 exhaust system that includes their 3" down pipe? ..is that a whole different part all together or is that usable in my application?

we beleive the car already has some type of clutch upgrade so im going to stick with it until it goes. i was looking into the 40mm tial wastegates like u recommended and wanted to know if theres a big disadvantage in getting a smaller (38mm) or a bigger (44mm) wastegate if i may go all the way up to 400rwhp?

 

Okay this is a little misleading it's not as much as the lbs you need to worry about it's more the HP because different sized turbos push different numbers at different PSI. So i would take more into consideration the output HP you want then worry about the psi, per se. From my understanding

 

They mean they will cut off the flange flush with the face of the turbo outlet and drill/tap four screw holes to afix that style of downpipe flange...


Their DP will be useless to you because of the location, the difference between a turbo DP and a regular DP is that you have a different flange between the DP and the header/turbo which causes them not to bolt up at all and interfere with each other if you were to attempt to...
Here is a good reference for exhaust in general. Look at the diagram in the article that is one of many turbo flanges on the top of the downpipe, now look at racing beat's flange, do you see the differences? In addition to the flange differences you will also have length and pipe styling differences too.

 

yea that makes sense. well, can anyone answer how much rwhp a stock s5 motor can handle??

Oo ok thanks. so im assuming i wont use their downpipe at all if i use a custom turbo set up?

 

aaron, which model haltech would you recommend for street use. im looking more for drive ability and could you elaborate on why a microtech lt-10 is better for track use and may not be the best choice for my application? thanks

im still reading up on things on the forums ect. and he has an lt-10 laying around that hes selling for 1100 so if i can save a few hundred for something that makes more sense than its the obvious choice lol thanks

 

Those statements probably refer to the stock turbo, which really becomes inefficient at around 14 PSI. The numbers are radically different once you start talking about aftermarket turbos and remember, it is not just pressure but also airflow that factors into the equation.

A turbo downpipe is the downpipe coming from the turbo to the rest of the exhaust. An "exhaust" downpipe would just be a generic term that can refer to many different things. The RB downpipe won't connect to an aftermarket turbo directly. It is designed to bolt up to the stock turbo and thus has a flange to match. At the very least you'll need to cut off RB's flange and weld on a v-band or flange to match the turbo. It may also require a bit of modification to the downpipe to make things line up. This is a standard issue when going with a full turbo upgrade.

At 400HP I'd say to go with the 44MM wastegate. It's better to over-wastegate than to under size. But the exact size that is ideal will depend on the manifold, turbo, downpipe and how it is all plumbed. For example, a 44MM wastegate may flow only as much as a 38MM wastegate if the recirculation pipe into the downpipe meets at the wrong angle.

As much as you can put through it until it breaks. 300-350HP is no sweat. After about 400HP, tuning becomes much more important.

Or you will have to modify their downpipe.

As I mentioned, the Haltech Sprint RE is a great entry level ECU for rotary engines.

The Microtech is not the best ECU for street use because it does not support:

-saving maps to disc
-closed loop operation
-3D timing tables
-configurable I/O
-it also has a poor interpolation method between load cells, which can make it very difficult to get a smooth tune
-software is very poor, compared to other ECUs

A used LT10 for $1100? Yikes. More capable ECUs are far cheaper.

 

Ooooo lol im beginning to think its a lot more simpler than i expected but it helped a lot that u broke it down for me the way i asked the questions =) ...

the lt10 isnt used and is still in package but has been sitting at his shop. not sure how warranties works on these things but hopefully it starts from the time its installed lol

i ended up buying a used racing beat rev ii for $450 today. came with all hardware, down pipe ect. im gunna ask my mechanic to modify the RB down pipe for my turbo setup as suggested

looks like i have everything under control thanks to the answers im getting in this thread. BW turbo, microtech ecu, KGParts fuel system, koyo rad/black magic fan, racing beat downpipe ect ect... all i need now is the manifold ..what do you think of this one? http://www.rotary-works.com/mm5/merc...e=RW-MF-RX7-FC

didnt want to go the ebay route but also didnt want to spend a fortune. does anyone have an opinion on these?

 

I'd still advise against the LT10. Trust me, it may not seem like those issues I mentioned are a problem now, but they will be major limitations once you start tuning the car. And if you intend to have a smooth running car that drives easily on the street, then 3D timing tables (the Microtech uses an odd timing method sort of modelled after a distributor), good interpolation, smooth injector staging and closed loop will be very important. For less money you can get a better ECU.

Good price on the REVII. You'll be very happy with that exhaust.

The manifold you link to is basically the same thing you'd get on eBay. Thin tubing, questionable welds, and the flange that meets the turbo is horrific. Here's what a T4 turbo flange should look like:

 

ok, ill see if i can get him to source me an haltech and tune it on that since i think microtech sells an lt10 brand new for the same price with warranty (?)... so im not exactly jumping on his lt10, just figured it was easy, available and something he was ready to do.

what do you think about the greddy mani listed here?

https://www.rx7club.com/2nd-generation-rx-7-1986-1992-parts-194/collection-awesome-jdm-parts-greddy-re-amemiya-etc-959313/

 

https://www.rx7club.com/2nd-generation-rx-7-1986-1992-parts-194/big-turbo-apexi-ihi-78-r-1-1-hotside-divided-rear-housing-t4-961752/

or maybe even the custom SS mani above for $150? he said he he mentions it only has a 38mm wastegate flange so im not sure how well that will fly but being SS it looks nice and should be light lol

 

Hot side on that turbo is larger than I would recommend for a stock or street port.

The wastegate flange can be easily swapped, so that's not a big deal.

The Greddy manifold is a quality manifold but the wategate runner is in a terrible spot. Leads to boost control issues.

 

???

are you saying you wouldnt recommend using the borg warner on my stock s5 engine unless its ported?

<----------new to this. thanks!

 

Correct. Anything over .96 or so on a stock port is going to cause unnecessary lag. In my opinion, the sweet spot for a stock port is right around .90 T4. Of course that also depends on the wheels in that housing, but in generic terms...

 

how can i tell if my turbo's hot side is bigger than a.96?

is the "hot side" another term for the A/R?

lol sorry im not familiar with what the hot side refers too lol
here are the specs listed for the turbo i bought:

-Borg Warner Performance S363 Turbocharger
-Compressor wheel Ind. 63mm extended tip
-Turbine wheel 71mm
-.88 turbine a/r
-Flows upto 67lbs/min
-supports upto 675-700hp
-included: T4 mounting gasket and oil drain gasket

SINGLE ENTRY INLET T4 FLANGE

 

Yes, "hot side" is slang for "turbine A/R".

If your tubine is a .88 T4 divided, then you're about where you want to be. It's a bit small for 400HP though won't prevent you from getting there. Right about perfect for 350HP.

 

o ok thanks. yea the hot side is a .88 a/r UNDIVIDED ...the wait for a divided would be 1-2 months THAN shipping. i figured on a hotside that small that the spooling difference would be nominal even if i waited for the divided.

but i guess i should expect 350rwhp from 12-14lbs on a stock port?? i would like more like 375-380 from 14lbs of boost

 

.88 undivided will work but won't be as responsive as the divided version. Figure about 500 - 1000 RPM difference in spool.

Why do you care what power level you are making at a certain boost level? As long as it is still at a reliable level (18 PSI or less) and within the turbo's efficiency, what does it matter?