EFR 6258 or GTX2867 twinscroll
 

I am currently trying to figure out which turbo I want to use for my build and would like to hear some thoughts from the more experienced people. My car is my DD and will see some autox and track days but relatively few. I am looking for a turbo that will get me to my horsepower goal (340 at the crank or 300whp) while remaining efficient and give me the best lowend power possible. So far it has come down to these two turbos, the GTX2867 or the EFR 6258.

Here are the compressor maps for each.

https://www.miataturbo.net/picture.p...pictureid=2404

https://www.miataturbo.net/picture.p...pictureid=2403

According to my calculations (pls correct me if I am wrong) would place me just to the left of the center line in the third efficeincy island for the gtx and just to the right of the center line in the second efficeincy island for the EFR.

So far the borg looks better and is cheaper however the GTX offers the option to go twinscroll but I am not certain how much better the spool would really be. If I were to go EFR I would just get a manifold from ABE and get my downpipe modified as well as new intercooler pipes. The internal wastegate should be fine.

However with the gtx if I chose to go twinscroll the turbo would run me $300 more then the EFR then I would need 2 external waste gates, $550-$600, a twinscroll mani +$200 over normal and the other mods I mentioned.

So my question is whether twinscroll would be $1,100 better or if I should just go with the EFR6258. Maybe there is a better turbo option that I haven't even though of currently. I am open to any suggestions.

P.S. I have been learning a lot but still consider myself noob so sorry if any of this is incorrect.

The 6258 will spool and respond SIGNIFICANTLY faster than a Garrett GTX2867. They are impossible to get right now, but I would wait for a 6258.

thanks for the quick response. I kind of figured this would be the answer which is kind of a relief considerign the massive cost difference between the two. How long do you think this shortage might last?

I make 200ft/lbs at 3k rpm with no spool helpers (VCIS not hooked up, stock head, stock cams, EBC configured to act as MBC)
https://www.miataturbo.net/showpost....&postcount=191

Very nice that is exactly what i was looking for and my setup will be very similar to yours when it is finished.

EFR6258 is also *SUPPOSED* to come in twin-scroll housing, but I don't think Borg Warner actually makes them yet.

http://www.speedforsale.com/nissangt...66p24hl1cs7qf7

6258. So much pwn in one package

I say you should go with the GTX2867, mostly so we have comparisons of how it does on the miata.

I think if the price difference wasn't so vast I might just do that but the more I think about it the EFR 6258 is gonna give me the kind of performance I am looking for and is proven. I would rather not spend the massive money for the GTX if in the end it might underperform the EFR6258 in everyway

I too say gtx so you can waste thousands on the garrett chra exchange progra
Just like all the other cool kids here

You know I have yet to see one of you BW people take your car out on the track dog on it and see how well it does.

Edit.
99mx5 has taken his car out on track. He has 2 days so far, with one of them ending in a blown motor.

I'm more than likely going to be swapping for out a GTX2867 while I wait on the motor build to finish... I'll be the guinea pig

Yah i am sure bw turbo would blow. But. Rebuild kit is 150 and you can DIY. At least with airwerks.

I think this speaks well of the turbo and not so well of the motor :giggle:

that's because it uses jew-bearings. efr has balls. you can't rebuild em, so its same as garrett.

except the EFR CHRA is hulk-sized.
https://www.miataturbo.net/attachmen...ine=1336683820

No doubt at all. I don't think the EFR's are going to be any major trouble out on the track. I also think that the 6258 is probably one of the best turbos out there for a miata right now. I just want to see a comparison dyno of someone with the GTX2867.

i found this

Built engine 1, stock engine 0 :giggle:

Saw this on another thread. EFR in pink. Yellow gtx2867

https://www.miataturbo.net/attachmen...3&d=1322003798

I find this extremely interesting. The biggest thing I notice is where the peak efficiency islands fall. The BW turbo's peak efficiency is at considerably higher pressure ratios. I'm too rusty on my compressor design theory to provide any really useful analysis... more reading is required... but it seems to suggest more power can be made with less boost on the Garrett. Maybe someone who knows more than I do will care to comment?