BNR vs EFR, anyone have a first hand comparison?
#1
BNR vs EFR, anyone have a first hand comparison?
I'm about to rebuild the engine in an fd I picked up. I kind of want to keep it stock, but then I was thinking about BNRs, but since that gets so expensive (turbos, fuel upgrades, and an ECU), I started thinking about an EFR suitable for about 400whp, since it looks like the BNRs are capable of that too.
Any thoughts? Would really like to hear from someone that has had both, or an unbiased tuner. I don't want to go with BNRs if its likely I'd just end up going to EFR after.
Any thoughts? Would really like to hear from someone that has had both, or an unbiased tuner. I don't want to go with BNRs if its likely I'd just end up going to EFR after.
Last edited by TwinCharged RX7; 09-09-18 at 11:05 PM.
#2
Rx7 Wagon
iTrader: (16)
If you're not married to the twins by law or religion, then the 8374 is the turbo you want for 400+
BNRs will make those numbers, but it'll be harder to get the setup right. The turbo control system and heat management will more challenging. If you run AI, then the 8374 will have more headroom. The twins will spool faster, but they'll have the quirky transition.
BNRs will make those numbers, but it'll be harder to get the setup right. The turbo control system and heat management will more challenging. If you run AI, then the 8374 will have more headroom. The twins will spool faster, but they'll have the quirky transition.
#3
The Ancient
My first upgrade back in 1995 was to a pair of Hitachi T25's run by the infamous Purple Box with tuning points every 2000 rpm. I have no idea what power I was making, but Peter said it was about 360 hp. I was a newb. But I really liked the power and know I could have made 400 with today's ecu's, crank triggers, and A/WI. I would be sorely tempted by some good twins making 400 hp.
#5
Eh
iTrader: (56)
I love Brian at BNR as he has been a great asset to the community for years. He is as stand up of a guy as it gets. With that said the 8374 setup is much more simple and produces a better power band from about 2800 rpms and up. The BNRs were an amazing up grade for years and still are. I love how they keep exhaust noise in check and a properly setup sequential car is a special experience. The EFRs on a rotary are just game changers, I didnt believe it myself until I drove one.
The following users liked this post:
Rocketeerbandit (09-10-18)
#6
The Ancient
djseven... Forgive me for asking, but I haven't followed newer turbos since going NA. What makes the EFR's so good?
Trending Topics
#8
Rotary Motoring
iTrader: (9)
The EFR turbos were designed for and are used in Indy Car and so are very race oriented turbos.
The very light Titanium Aluminide EFR exhaust wheel is indeed like a proverbial leaf in the strong wind of the rotary exhaust and are sized up from the typical piston engine exhaust wheel sizing.
Another nice feature is the Compressor Bypass Valve (BOV) is built into the front compressor cover, so when you let off the gas the boost recirculates into the front of the compressor housing through the anti-surge slot. The effect of this direct re-circulation is the compressor wheel does not slow down nearly as quickly when you let off the gas and so full boost is available much sooner between shifts or when modulating the throttle under boost.
They also have a stainless steel exhaust housing, dual shaft seals (great with high rotary oil pressure) and large very robust dual row ceramic bearings. The Internal Wastegate versions have dual wastegates on the dual scroll versions and large, well flowing wastegate designs.
On a piston engine the EFRs are pretty good; on the rotary they are really a game changer in my opinion as well.
The very light Titanium Aluminide EFR exhaust wheel is indeed like a proverbial leaf in the strong wind of the rotary exhaust and are sized up from the typical piston engine exhaust wheel sizing.
Another nice feature is the Compressor Bypass Valve (BOV) is built into the front compressor cover, so when you let off the gas the boost recirculates into the front of the compressor housing through the anti-surge slot. The effect of this direct re-circulation is the compressor wheel does not slow down nearly as quickly when you let off the gas and so full boost is available much sooner between shifts or when modulating the throttle under boost.
They also have a stainless steel exhaust housing, dual shaft seals (great with high rotary oil pressure) and large very robust dual row ceramic bearings. The Internal Wastegate versions have dual wastegates on the dual scroll versions and large, well flowing wastegate designs.
On a piston engine the EFRs are pretty good; on the rotary they are really a game changer in my opinion as well.
The following users liked this post:
gmonsen (09-11-18)
#9
Eh
iTrader: (56)
The other guys above covered it well. The response, down low torque and full power band is unmatched by any other turbo setup on a two rotor. I'm going 7670 on my 95 car as I had the 8374 on my last. I want to experiment with the 7670 and the pettit ecu to see if I can keep the factory driveability(minus 3k hesitation hopefully) and get a more simplified setup than the factory sequential with even broader power band. I have done similar 10 years ago with the Apexi RX6B and 57mm garrett turbo. Neither offered the same spool as the EFRs though.
The following users liked this post:
gmonsen (09-11-18)
#10
Full Member
iTrader: (5)
Great topic! I'm going BNR's but largely just because I love the sequential twin turbo design and just wanted to make some more power than the stocker twins.. I've also put a lot of work into upgrading the twin turbo control setup so I'm hoping to not run into some of the other reliability pitfalls of the stock setup (fabco solenoids, new silicone vac lines).
I haven't experienced both, but my take is unless you're pretty attached to the twins, an EFR is probably the best way to go in that you get lots of advantages in being able to get rid of all of the complex twin turbo control system (solenoids, vac/pressure chambers, etc), save weight, produce less heat and possibly make more power (depending on which you go with) while not really sacrificing spool. I still haven't really seen back/back comparisons of BNR3 vs EFR to really quantify the spool-up, though. Anyone know if something like this has been done?
I haven't experienced both, but my take is unless you're pretty attached to the twins, an EFR is probably the best way to go in that you get lots of advantages in being able to get rid of all of the complex twin turbo control system (solenoids, vac/pressure chambers, etc), save weight, produce less heat and possibly make more power (depending on which you go with) while not really sacrificing spool. I still haven't really seen back/back comparisons of BNR3 vs EFR to really quantify the spool-up, though. Anyone know if something like this has been done?
The following users liked this post:
Rocketeerbandit (09-11-18)
#12
Full Member
iTrader: (5)
Oh yeah, I didn't mean on the same car, unless someone had the BNRs and then was switching to an EFR already. It would be cool to see even just different cars run w/ each of the setups on the same dyno.. preferably with similar engine setups (not one w/ stock ports and one bridged or something haha).
#13
Rotary Freak
iTrader: (12)
I don't have much to add, only that when my turbos went, I decided on BNRs. I don't doubt what people say about the EFRs, but for some reason (maybe just nostalgic after owning FDs for 17 years), I just love a properly working sequential turbo FD. It's a pain in the *** to get right, and produces a ton of heat, but it stays in family with how the car left the factory, and gives you close to 400 rwhp at 15 psi.
From a cost perspective, BNRs are cheaper. Also, you can keep your airpump - mine is pushing close to 400 whp with a cat and airpump w/ no rotary stink. Car is fast as hell, and has great low end response. I've owned 3 single turbo FDs, two pushed over 450 rwhp on pump, and I'd take this car any day over them.
Also, adding new parts is a bit easier since they are made for this twins - if you buy a new intercooler, air filter, exhaust, etc. you don't need pipes made, etc.
I'm sure an EFR setup is great, but properly working sequential BNRs are pretty great too.
From a cost perspective, BNRs are cheaper. Also, you can keep your airpump - mine is pushing close to 400 whp with a cat and airpump w/ no rotary stink. Car is fast as hell, and has great low end response. I've owned 3 single turbo FDs, two pushed over 450 rwhp on pump, and I'd take this car any day over them.
Also, adding new parts is a bit easier since they are made for this twins - if you buy a new intercooler, air filter, exhaust, etc. you don't need pipes made, etc.
I'm sure an EFR setup is great, but properly working sequential BNRs are pretty great too.
#14
Spoolin'
iTrader: (6)
The other guys above covered it well. The response, down low torque and full power band is unmatched by any other turbo setup on a two rotor. I'm going 7670 on my 95 car as I had the 8374 on my last. I want to experiment with the 7670 and the pettit ecu to see if I can keep the factory driveability(minus 3k hesitation hopefully) and get a more simplified setup than the factory sequential with even broader power band. I have done similar 10 years ago with the Apexi RX6B and 57mm garrett turbo. Neither offered the same spool as the EFRs though.
#15
Eh
iTrader: (56)
I pulled the drive train(99 twins etc) out of the 95 car and it’s now in the 93 BB car in selling. I have a long list of upgrades to install in the 95 car and if my work schedule slows soon I’d like to believe it will be running with the 7670 sometime around the end of the year.
#18
Spoolin'
iTrader: (6)
Interesting.
Are you in stock fuel system with stuck fuel pump?
How much boost were you running on the Garrett?
[Johnny Kommavongsa;12387349]^ no updates. Was at djseven house this wknd and car still needs some work.
I tried a pettit ecu on an 57mm Garrett turbo and I noticed the afrs leaning out.[/QUOTE]
Are you in stock fuel system with stuck fuel pump?
How much boost were you running on the Garrett?
[Johnny Kommavongsa;12387349]^ no updates. Was at djseven house this wknd and car still needs some work.
I tried a pettit ecu on an 57mm Garrett turbo and I noticed the afrs leaning out.[/QUOTE]
#21
Full Member
Coincidentally, I just took delivery of BNR stage 1 twins today. They are almost too pretty to install in the car!!! :-) BNR packed them extremely well - so well that even UPS couldn't harm them!!!
Like others in this thread, I wanted to stay close to stock. The twins allow me to do that and I expect the performance will be really good too.
Like others in this thread, I wanted to stay close to stock. The twins allow me to do that and I expect the performance will be really good too.
#22
Put it in the microwave!
iTrader: (22)
Coincidentally, I just took delivery of BNR stage 1 twins today. They are almost too pretty to install in the car!!! :-) BNR packed them extremely well - so well that even UPS couldn't harm them!!!
Like others in this thread, I wanted to stay close to stock. The twins allow me to do that and I expect the performance will be really good too.
Like others in this thread, I wanted to stay close to stock. The twins allow me to do that and I expect the performance will be really good too.
share the experience . oh and photos ! cheers
The following 5 users liked this post by wutangben:
djseven (01-02-20),
pd_day (01-11-20),
scotty305 (01-08-20),
silverTRD (01-03-20),
Smokey The Talon (01-10-20)
#24
Senior Member
iTrader: (5)
I've been having this self debate quite a bit. I like the twins because, well, that's what the car came with and was envisioned with. The EFR is soooo nice though and I can reduce heat, remove all those vacuum lines, and increase engine bay aesthetics, while having comparable power if not greater power results.
but the original vision...
I'll probably have this debate up until the day I pull the trigger.
but the original vision...
I'll probably have this debate up until the day I pull the trigger.
#25
Life is Beautiful
iTrader: (2)
^If it helps any, I'm fairly certain that had Mazda engineers had the option of the EFR 7670 being available to them 25+ years ago, that's the actual performance "vision" they would have preferred. At stock levels, both configs are very comparable. However, the 7670 gets the engineering edge for the practical reasons you state.