TheKeeper

Maybe a t-shrt? We're excited to see someone else test the twins.

You ARE the first retail set. There is ANOTHER set heading to Australia soon as well. We know our results on the RB26 here in the states, but are eager to see how you like this set up.

Yup.. they sound like Darth Vader at idle. It's a very common theme with RB26's and larger twins, and some surge until you hit WOT. The 6258's show no signs of this and they are rated at 450hp. Next up will be the 6758's to see if they ride the choof choof train to Vaderville, or like their little brothers, speak softly and carry a big stick...

I think it's more of a terminology issue here. MOST turbos (about 2530 and larger) on the RB26 seem to "fight each other" in a shuffle. I have heard many cars that do it slowly and in a whisper even at idle, only to get worse as load increases. The only way once the turbos start this "shuffle" under load is to hope you can drive right thru it or back off the throttle and immediately return to WOT. The 6258's have been proven not to do this... I'm sure you can search and find a lot of info on this phenomenon. It can be quite annoying.

It's not the lack of effort to get these in the right people's hands, it has a EVERYTHING to do with the lack of product. Once the product is more readily available you'll probably get all the information you want/need. (yes, I'm at Full Race)

Found it on Full Race's facebook page ---> https://www.facebook.com/full.race

I know there is 6258 on a stock SR20 motor that dyno'd at 340 to 360whp (from memory) on the crappy U.S. west coast 91 octane fuel and the owner was praising the linear torque curve. I'm not sure if that dyno plot is online anywhere or not... The twins on the RB26 work well, and don't "shuffle/surge" like other applications which I personally think is a huge selling factor for larger twins. (The 6258's are rated at 450HP)

I think Eric explains it in this article he wrote. Eric works for Cosworth and is a very reputable tuner. I'm heading out the door, but if the info is not in there it's a good read anyway... http://www.motoiq.com/magazine_articles/articletype/articleview/articleid/1750/borgwarner-efr-turbo-feature-set.aspx

Just a simple track like our ButtonWillow Raceway Park track where a lot of time attack events are held has over 15 (on boost) shifts and between 22-25 transitions from off boost to on boost. (Evo) The Sierra Sierra team noticed a decrease in "on boost" transition time from one ball bearing turbo to the EFR, so I'm sure you'd see more when changing from journal to BB. Whether or not it's measurable enough for you make the jump is one thing, but it's there. To be fair, much of that could be contributed to the internal blow off valve.

I've been called a lot of things, but naive has never been one of them. That car is running the 8374 with the .92a/r housing on it. The car was suspected to have a boost leak when it was first dyno'd, which was found to be the case and has not been dyno'd since...and probably won't be for a few months. That car resides in AZ and it's about 110ºF (43ºC) there, and dyno season is over until September. Ha!

Here's an EFR taking a beating and has taken quite a few of these and seems to running perfectly fine.

BigMike, maybe you should change your screen name to BigSkeptic. Honestly? Just because BorgWarner wrote that you assume it's just sales pitch hype? One of the most trusted names in the automotive business and you're going to "skim over it", there may be good information in there. That being said, I believe that if you are looking for the best bang for the buck you are not looking at the EFR turbo line. Period. You can buy a Neon SRT4 instead of a Viper, a Chevy Cobalt instead of a ZR1, a 370Z instead of a GTR and yes... a journal bearing turbo instead of an EFR.

BigMike, I can help with that. I don't think anybody will argue with the fact there ARE some advantages to ball bearing turbos. Let's just forget price for a moment. If you, BigMike, were to set out to build the top of the line turbocharger that would be unrivaled by any other turbocharger with a lot of UNIQUE FEATURES you would not leave ball bearings out of the equation. Simple as that. Now, if they kept all the other features and only added ball bearings I could see your point, but that's far from the truth. Is it worth that extra cost? well... that's up to you. And me. And everybody else that decides to open their wallet for their next turbocharger. And to answer your question, yes it does add up even over a lap when you are talking thousandths of a second difference between first and second. But then again it's your choice as to whether you want to play at that level, and if you do... you need the best equipment available. Seems simple to me.

Actually BigMike there is a BIG difference between dyno/drag racing and road racing. If you have a sequential gear box the gap between the two diminishes significantly, but most people do not. Good road race drivers are very methodical with their shifts, and there is a longer time from throttle off to boost again than in drag racing. As we all know this is to keep from upsetting the balance of the car. (and increase longevity...to finish first you first have to finish) Also, blipping the throttle (does not happen in drag racing or the dyno) is to keep the revs in "the quick boost zone", but not actually IN BOOST. These turbos (and most other ball bearing turbos) recover faster than journal bearing turbos during these transitions. So there is a significant difference over an entire lap, session or race.

The ONLY thing I have ever used a dyno for was to ascertain whether or not certain modifications yielded a gain, and if so how much. Same dyno, same settings, same gear, different mods.

I like to see 4th gear pulls as well as anybody on the dyno, but it's really not necessary when you plan to use the same gear and same dyno. (as long as it's not first or second as we all know) It's just very hot here and loading 4th gear is a long run. It will yield a faster spool and possibly more HP on most dynos, but not always worth it. I'm not sure Harey how you say you've never seen it other than maybe every pull you've been associated with has been 4th gear. Since we know the difference between 1st and 4th can be 1,000+ RPM, it stands to reason there is a difference between 1st to 2nd, 2nd to 3rd, 3rd to 4th, 4th to 5th....etc. The in car video shows only 1,000RPM range, but over a bar (1.2 if I remember my MFD's correctly) and it must be 4th or 5th gear because it spools quite a bit in that 1,000 RPM from 3,000 to 4,000. I can guarantee on that particular dyno a 4th gear pull would have shown faster spool and more HP.

Actually I have seen as much as 30whp increase and 400-500RPM faster spool in 4th gear vs. 3rd gear on Mustang dynos. Otherwise you could just run 1st gear and get the same results if you could strap the car down well enough, but the fact that the RPM's increase so quickly the turbos cannot be loaded properly for an accurate reading. I see in the in-car video it looks like the car spools from zero bar at 3,000RPM to 1.2 bar before it gets to 4,000 which tells me that on the road I bet those spool to 19psi by 4500RPM or so... The 6258's are rated at 450HP each.

Mustang dyno at the wheels.

I dunno, maybe a 4th gear pull would have been a better indicator for that? The 6258's look like they could get you to 900hp according to BW, so they are not exactly small, but I agree with you based on this dyno chart.

I know the tuner, and know that dyno. I also know that those pulls were in 3rd gear, so it looks less impressive than a 4th gear pull. It's getting HOT in AZ so 4th gear pulls on that dyno really work the cars harder than necessary. I'm sure Geoff will post up when he gets a chance, he's up to his ass in the new race car build over there at Full Race.

I know that dyno reads notoriously LOW, and I think the single was found to have a boost leak which is why it wanted to drop boost up high. The torque curve looks nice on the twins, but I agree with Lithium we need more boost to see what they really do.

Geoff currently doesn't have a turbo on his R14. His car has been sitting in his shop since the Modified event last year. The Blue R34 in Borg Warner's booth had an 8374 twin scroll in it. The results haven't been posted yet because the owner of that car has not put in on a dyno yet. There is also an RB26 that has the twin configuration on it with the EFR 6258's. Not sure if there are numbers on it yet either, but the biggest concern for most is that they DO NOT SHUFFLE. I've had a few twin turbo set ups on the RB26 and anything that could produce over 550whp seemed to "shuffle" (surge)... so that was good news.