BNR stage III, but what engine port to go with??
 

I have searched and most topics concern how the BNRs are liked, and/or how they compare to other set ups. I have the stage III's already, car runs great but for future reference when time comes i would like to know my best options.

The car is a weekend only driver, and not every weekend at that. So DD reliability is not as much a concern. I do want to make optimum power on these twins so......
What port would work best with these twins? Should I go full bridge, half, street, agressive street?? Ahhhhhh to many to choose!!

There are so many people out there that do porting, but I always here how one persons port work can be so much different from another, Banzai, rx7 store, Pinapple, etc etc. how do you know one persons street or brige is not different form another?

So you know i have....

BNR III's sequential
550 & 1300 inj
FULL 4" exh
3" DP
ARC smic
inovative WB
PFC
HKS Ign
modified stock air bok with K&N

Healthy streetport

Id do a streetport, half bridge might work good too but since its a weekend car and not a track car thatd be pretty much overkill IMO, plus a healthy bridge idle would call even more attention to an already standout car.

go balls out... Peripheral port, you dont really need to idle anyway.

Healthy streetport will yield good results. No point in going with the half bridgie if you're sequential. Man oh man are you going to love the powerband :)

Here's how a mild-to-medium streetport pulls with sequential BNR Stage 3s....

https://www.rx7club.com/showpost.php...52&postcount=9

Would BNR Stage III an overkill on 53K miles stock motor with following mods? hp?

Apexi Intakes, HKS DP, RB DT catback, Trust SMIC, PFC, 550/1200cc, Supra TT pump, ACT/9.5 flywheel.

Dude, get a midpipe and the BNRs, crank it up to 15-16 psi and have fun. :)

are you being serious or sarcasm :-)

Serious. I run about 17psi on mine and they rip. But I am now maxing out my fuel system... 850s and 1300s :(

Yes a weekend car but my monster HEHE, Im not worried about idle or others thoughts, just the optimum from these, so thats why i was thinking half bridge.
cheers

haha and what would be considerede a "healthy streetport"? Im just not sure what to tell the builder.
Is it true one mans work can be different from anothers porting job?

How are you maxing out, I have 550 and 1300 tuned by Steve Kan and he said there is plenty of fuel left at 16psi?!

Half bridge is a waste of time, if your gonna go bridge go full bridge.

I was serious, if that's what you want for the car. If you are content with driving around at 12-13 psi with the stock cat, I would not spend money on new turbos unless your's are shot.


To the guys recommending anything more than a streetport.....these are SEQUENTIAL TWINS. There is no point shifting the powerband farther up than a streetport already does with the stock exhaust manifold. A bridge-port would be wasted with sequential twins and has too many compromises as compared to a streetport.

Not sure, Mine is very strong and running at 11.2 A/F. It has a Steve Kan special port job on it, maybe that has something to do with it. I have seen Injector duty spikes to 100%, very scary.

Any opinions on the "judge Ito street port"? I have seen his template going around but have heard mixed reviews on it. Any feedback on that?

^

A half-bridge, such as mine, would be a waste on your sequential twins. If you had a large single turbo then yes, a bridge-ported motor would be right for you. Since you still have twins, especially since you are running them sequentially, a street port would be a better choice for your setup.

I've heard rumors of stuck side seals. I have no firsthand experience, perhaps he'll chime in......

Thanx rich, this what i mean by how not all peoples porting jobs are equal. Ones streetport can be different from anothers, So how do i know that the person doing the porting will give me the "healthy steetport" that im looking for? Optimum porting with out doing damage?

I do see your point, especially being sequential. The reason i though half bridge would be ok was becuase i assumed the BNR's could flow more, enough to support this type of porting job

I think for non-seq BNRs at 17-19 psi a bridgeport might have it's place. Sequential, not so sure.

Re: the porting, just find a reputable porter/builder. Hell, ship me the engine :)

Thanks for all the good impute on this thread, this is definitely helping to shape the plans on my FD project.

I just thought since I was reading this I'd bump it to the surface to show people that there is a search function on this website... lol

^--- agreed

no issues at all with my aggresive streeport template as far as sideseals. Now the "Wild Streetport" template is something I personally tried and was not worth the headaches. I never sold the wild streetport.

Anyone have any coments on their ITO ported motor??

Just slightly off topic here- where's a good thread with discussion about porting theory?

Things such as the width of the port vs "lift"(depth?) and duration?

https://www.rx7club.com/rotary-car-performance-77/

There is a section where you can inquire about porting.

Thanks, but i was asking here because i figured the regs would chime in- rather than start a whole new thread just to find another thread that i was actually looking for.

Thats an awesome dyno chart! How do you think you would do with 850/1600cc's?

You can only have a street port that goes so far. The whole "special" thing is a load of Sh#$t. With the stock twins, I wouldn't even port the motor. Your not going to "feel" 20hp.

i was wondering about that aswell, not so much the 850scc prim but 550s and 1600s i would think be more than enought with lots of room. any reason why no one does this? (that i know of)

so would 550/1300s be enough for 15-16psi BNRs? Some people are saying yes and some no, I just want to clear it up.

I thought it was more like 50HP to be gained from porting with twins?

A car I was looking at buying on down here has 60TRIM T04E prior blowing a coolant seal with stock ports it made 354 WHP. After blowing the engine and street porting and scalloping the rotors same turbo it made 415 WHP same tuner/ecu and at the same or very close boost (claimed) 17 PSI and same dyno.

The engine was a T2

That turbo should be in the same range as the stock twins (when NS)

The dyno sheets which I did see did not have boost pressure referenced so who knows it could have been way different boost levels.

Yes, your fine.

You answered your own question. We are talking stock twins. Its a matter of CFM.

This thread is actually about BNR twins.

Are you saying the BNR twins which seem to support about 415 WHP at 17-19 PSI are going to be pushing a different CFM than a medium single at the same boost and HP level?

Every turbo flows differently. Thats what a flow chart is for. Even if you can't read one, think of it this way. At 10psi my GT42R is going to push more cfm then the BNR twins would at 25psi. 17-19psi is going to generate alot of heat from the twins, which isn't good either. Like I stated, porting a motor with twins, (BNR or not), is for the most part a waste of money. Im not saying you won't gain from it, but not enough to warrent the extra time, effort and money. I went 10's on stock ports. How many have done that? Not being arrogant, just affirming my point.

I'm not comparing a GT42R to the twins, I'm comparing them with a 60 trim TO4E.

Again what I said, different turbo's, same boost same HP are you saying they would have different CFM of flow?

A street port, costs about 50 dollars worth in carbide bits, 50 dollars worth in templates (if your not designing it yourself) and takes a few hours, even if its only worth 20 HP that still seems like a good deal.

Also I can read compressor maps, and I know why a larger turbo makes more power than a smaller one at the same boost. Thats not what I asked you.

Keep in mind most first time porters will frag a couple of housings.

Also, I ran the piss out of the BNRs at 19 psi and I was surprised by how well they handled the boost wrt intake, coolant, and engine bay temps.

Ive ported heads before, after that the one time I ported a rotary engine was pretty easy.

large street-port.

Im still learing, but going from 550, transitioning to 1600 could create a slight bog, referring to the www.rx7.com 3rd gen fuel calculator. But perhaps thats just a matter of tuning? Or just the stock fuel pump is the only thing holding it back?

What would be good injector sizes for running the BNR stage 3's at 18 psi, on a good streetport with room to expand in the future? (e.g. 20 ~ 25 or+ psi) It may be counterproductive to max them out that hard, but after I get running smoothly on 18 psi, ill surely be looking into it. Even at the cost of new turbos, I think itd be worth it to experiment.

YES, different turbos at the same boost will have different CFM. As I stated before. I made 580whp at 20psi. A T78 will make about 450whp at the same boost "because" of the CFM each turbo makes. Thats why I said a flow chart will show you much better of how each turbo flows.

Again I said same boost and same power level for that amount of boost.

So lets say for the sake of example a T04E 60 trim makes exactly 400 WHP at 15PSI.

on the same day on the same dyno on the same engine and car.

BNR TWINS makes exactly 400 WHP at 15 PSI.

Are you saying that using the example above they would have different CFM?

There's no need to experiment. Bryan at BNR has told me many times that these twins won't be efficient above 19 psi or so. He (obviously) knows the specific specs on the the comp and turbine wheels.....I think 25 is a pipe dream.

550s and 1680s will work fine for you, and as far as fuel pumps go, check out my thread in the 3rd gen archives 'some fuel pump ramblings,' it's pretty relevant to your setup.

19psi is too much for BNR's hmm.. well even tho whos really gunna want 20psi on a daily driver lol.. 19psi is plenty for the street id think.. :-)

now there will be the guy who will want 25psi on the street pop up lol :-)

I have BNR 3's and recently installed a Pineapple motor with a large street port. The power band is broader and definitely feels stronger all around than the stock ported motor. I was concerned about loosing low end with this setup, but in fact, it is stronger all around. It seems to take about 30% less boost to get about the same power with this setup (relative to stock ports).

why not BNR 3 + AI? :D