BorgWarner 6258 on 910 engine?

[snowrx]

I'm still looking for a internal wastegate turbo to replace my existing  big chunk of' cast iron.

Has anyone looked over the divided scroll B/W 6258?  Small lightweight wheels with modern aero, water cooled ceramic ball bearings, integrated compressor recirculation and a stainless divided scroll turbine housing ticks all the boxes for me. The offset turbine outlet should give me room for a T3 > T4 adapter also.  Putting it on a Alunox exhaust manifold, but not looking to grenade my Citroen transaxle with more power, just to simplify and add lightness by losing all the cast iron in the external wastegate manifold assembly, and hopefully pick up some boost response on the bottom end.

 

http://www.turbos.bwauto.com/files/pdf/179359-EFRTechPages.pdf

 

It seems the new item is shipping with a .80 a/r divided scroll rather than the listed .92, so the above link may be out of date. Current part number is a 11589880036 for the .80 T4 housing turbo.

 

Maps on BorgWarners MatchBot app seem to make it look feasable:

(hang on, this is a monster URL)

 

BorgWarner MatchBot

[Andyww]

But you wont get that "thwunk" noise!

 

Thats the main reason I would always keep my old fashioned wastegate!

[plumdeplakmuis]

Hello Thomas, 

 

Looking at your matching, all numbers look a bit conservative, 

your 233 hp, could probably be achieved with a flow below 0.18 m3/sec.

Which corresponds with a more modern turbo at a 56mm compressor wheel, opposed to the 61.4mm proposed turbo. 

This can be mated with a ~47 or 48mm turbine wheel. 

 

So basically i think the BW turbo is a bit to large, and you can use something smaller. 

 

Also you have to take into account, that the twin scroll turbine needs a specific manifold with equal length headers, 

splitting the specific cyliders al the way to the turbine entry. A std manifold will not work. 

[snowrx]

I agree it's large. I ended up selecting the BW6258 as it was the smallest water-cooled modern turbo I could find with a divided turbine housing that included an internal wastegate to match my equal length divided manifold . I'm hoping the low boost requirement, twin scroll housing and the lightwieght ball bearing rotating assembly will at least match my old OEM Garrett.  I'll try to update my results after this winter's engine freshening and turbo install.

 

My old fashioned wastegate makes me make profane noises when it sticks shut and I have to contemplate the siezed bolts holding it onto the housing. It pegged my boost gauge once too many times!

[plumdeplakmuis]

If you want a modern smal size twin scroll watercooled turbo.

Try a Renault F4R 874 unit, much smaller than the BW, and can provide sufficient flow for your required output.

Also general shape is good and compact . Although you need to shorthen the compressor cover exhaust length a bit.

[snowrx]

 I'm just starting to tune my boost with it, so I can't say much about performance yet. Boost is opening the wastegate at about 2600 rpm at present and I have to break in the new motor before I know how high it will go. Butt dyno says it's going to work out fine, but I have not compared datalogs to see what the before and after boost curves look like.

 

I have the early fragile transaxle, so I ordered it with the low boost wastegate canister to run 8-10 psi max, hopefully gear limited. I'm now wondering if I should of used the default medium canister because with 9 (out of 10) turns of preload the wastegate is holding at 6.3 psi and I don't think I'll get to 8 psi on the wastegate canister alone. 7 psi may be fine as a base setting once I get the boost solenoid regulating things.

 

I'm running it on a '85 G-car, so by the time I added a T3 >T4 adapter it was mounted higher and farther forward than the OEM Garrett, so my exhaust and intake routing was a little tight.  In retrospect, I should of orderd my exhaust manifold with a T4 divided flange and saved some space. I couldn't bring myself to hack up the Aluox manifold to weld on on. 

[snowrx]

Here's a MAP/RPM chart of the turbo, controlled at 160 kpa but tuning is not done yet (is it ever?) Fairly quick to target, and will peg the boost gauge before you can lift the throttle if not controlled.

Edited December 24, 2015 by snowrx