Still running strong. Changed to 3.5" exhaust and response is better. Turbo is immediate, only ever notice lag if i botched something.

Having never driven an efr turbo but seeing the dyno results i still think it would be better, but for this size turbo on a rotary could be diminishing returns. Although for a serious SSM car it would likely be right at home. My car is far from a competitive SSM build, could be a second or more off if driven well, but i think most of that time would be gained in aero and better dampers. The s256 for the money is great.

 

EFR 7670

I did my low boost tuning Friday and hopefully will finish high boost tuning Sunday or during the week.

The spool is really good, full boost between 2,500rpm and 3,000rpm depending on boost.

I had a mismatch of springs in the wastegate so they were waaay to soft (open @ 7psi). I have 13psi springs in now so hopefully response is a little better.

We did some 28psi pulls up to 3,000rpm before we had to stop because of a melted dyno strap.

369ftlbs/240rwhp at 3,200rpm @ 28psi boost on a dyno dynamics.

I have never seen a 13B with so much low rpm power.

 

369 lb/ft at 3200rpm??? Thats very impressive. This makes me really want to go for the EFR IWG turbo

 

The closest equivalent BW EFR model is the 7163 Indycar turbo; about the same compressor (57i/71e), slightly larger 63mm turbine, 0.85 A/R or 0.80 in a T4 twin scroll. Given the recent results of the other larger EFR turbos I have to wonder if an EFR 7163 would set record low rpm tq/hp numbers that nobody ever thought was possible?



.

 

Given the recent results of the other larger EFR turbos I have to wonder if an EFR 7163 would set record low rpm tq/hp numbers that nobody ever thought was possible?

Yes, that is the dream turbo set-up for my FD. Sequential twin EFR 7163.

Not only does the 7163 have less mass/leverage and favorable compressor map for low rpm, but my adventures with mis-machined turbo housings tells me the mixed flow exhaust wheel will spool like a madman on the rotary.

 

This is what I managed in my FC with EFR7670 on an old HKS T04Z FD manifold modified for dual 44 wastegates.

This is boosting to 26psi and then starts to fade after ~6,000rpm down to 20psi by redline. I don't know if the boost fade is because I am running 13psi springs in WGs (so I can run pump gas on street) or if the little compressor is out of flow at 6,000rpm.

Engine is early opening street port with near stock closing, 8.5:1 rotors.

 

he only has a single Precision turbo which I perceive to at least be equivalent to the EFR 7163, and seems to be doing better than your 7670 setup

(fast-forward to 0:16 on the vid)



granted you claimed not to be fully tuned on the top end, but in general the 7670 seems to have a more peaky Pr - mass flow relationship than some of the other sizes ...

 

The Precision 55mm wheel is -
50 trim
Wheel Inducer: 55mm
Wheel Exducer: 75mm

Turbo: Custom Precision Turbo HP5530SP with .78 AR T3 exhaust housing twin scroll, the exhaust wheel is a 60mm/84trim.

I don't think the 71mm exducer EFR7163 can move nearly as much air as the 75mm exducer compressor of HppRX7s set-up.

I think HppRX7's turbo is closer to the 76mm exducer on the EFR 7670 that I chose. Still, quite a different turbo!

It is interesting to note how similar the power curves are despite the very small 0.78AR T3 exhaust side with 60mm wheel on his versus the larger 1.04AR T4 exhaust side with 70mm wheel on mine.

His smaller turbo makes MORE top end power, but that is likely due to my boost dropping from 26psi to 20psi on the top end and the tuning.

I think a EFR 7163 would be a bad *** 300hp turbo on a peripheral exhaust port rotary, but I don't see it getting into the 400hp range. Maybe on a Renisis where you don't lose so much of the compressor map out the exhaust port.

 

We should also mention that you can't compare dyno figures as it is very well known that MOST workshops enjoy correction, loose straps etc etc.

 

just by the numbers the Precision is a hybrid 3076R, I don't doubt that their impellers on either side flow different than the Garrett though given the result

HppRX7 Precision 5530
55.0mm inducer
76.0mm exducer
60.0mm turbine @ 0.78 A/R EWG T3 divided
HC in^2 area ratio: 4.383/5.358 = 0.82

Theoretical BW EFR7163
57mm inducer
71.0mm exducer
63.0mm turbine @ 0.85 A/R EWG V-band or 0.80 A/R IWG T4 divided
HC in^2 area ratio: 4.832/5.046 = 0.96

Blue TII BW EFR7670
57.2mm inducer
76.0mm exducer
70.0mm turbine @ 1.05 A/R EWG
HC in^2 area ratio: 5.965/5.507 = 1.08

to be honest Blue TII, you have your own thread and I didn't post here to discuss the 7670 in general or your situation in particular. I'll be happy to discuss it over there instead if you like.

 

to be honest Blue TII, you have your own thread and I didn't post here to discuss the 7670 in general or your situation in particular. I'll be happy to discuss it over there instead if you like.

I was inspired by this thread to try a smaller turbo for auto-x and stated as much here. I re-entered the discussion 5 months later because of your comparison of the original poster's turbo to the much smaller EFR 7163.


The closest equivalent BW EFR model is the 7163 Indycar turbo;

Good luck with that! 7163 is an awesome turbo; I will take two of them.

 

Well, If I could get in the garage and finish my new project I might have some new numbers to compare with. I will be changing a couple of thing to say the least. I am just now trying to track down a couple of boost issues ( lack of) and I should be able to get on a dyno shortly after.

This is the set up I tried to get going before 2014 Solo Nationals but had to abort a week before and put in my tried and true Precision "the little turbo that could" back in.

Thanks for the all the in site from everyone. I always second guess my set up after reading some of the posts. lol.

 

No truer words have been spoken