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-   -   BNR stage III, but what engine port to go with?? (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/bnr-stage-iii-but-what-engine-port-go-577667/)

Judge Ito 12-22-07 12:37 PM


Originally Posted by GoodfellaFD3S (Post 6094359)
I've heard rumors of stuck side seals. I have no firsthand experience, perhaps he'll chime in......

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.

Mazdabation 03-22-08 01:37 AM

Anyone have any coments on their ITO ported motor??

NissanConvert 03-22-08 09:30 AM

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?

skir2222 03-22-08 06:16 PM


Originally Posted by NissanConvert (Post 8006390)
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.

NissanConvert 03-22-08 11:01 PM


Originally Posted by skir2222 (Post 8007633)
https://www.rx7club.com/forumdisplay.php?f=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.

slayerx7 03-23-08 09:45 AM

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

ErnieT 03-23-08 12:16 PM

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.

FD3S2005 03-23-08 12:56 PM


Originally Posted by slayerx7 (Post 8009321)
Thats an awesome dyno chart! How do you think you would do with 850/1600cc's?

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)

ArmenMAxx 03-23-08 02:13 PM

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.

slo 03-23-08 02:24 PM

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.



Originally Posted by ErnieT (Post 8009658)
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.


ErnieT 03-23-08 02:29 PM


Originally Posted by ArmenMAxx (Post 8009971)
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.

Yes, your fine.

ErnieT 03-23-08 02:31 PM


Originally Posted by slo (Post 8009994)
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.

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

slo 03-23-08 03:20 PM

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?




Originally Posted by ErnieT (Post 8010007)
You answered your own question. We are talking stock twins. Its a matter of CFM.


ErnieT 03-23-08 04:37 PM


Originally Posted by slo (Post 8010154)
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.

slo 03-23-08 10:14 PM

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.


Originally Posted by ErnieT (Post 8010362)
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.


GoodfellaFD3S 03-23-08 10:28 PM

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.

slo 03-23-08 10:30 PM

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


Originally Posted by GoodfellaFD3S (Post 8011699)
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.


Ked63madison 03-23-08 10:34 PM

large street-port.

slayerx7 03-26-08 05:34 AM

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.

ErnieT 03-26-08 07:10 AM


Originally Posted by slo (Post 8011609)
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.

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.

slo 03-26-08 07:20 AM

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?






Originally Posted by ErnieT (Post 8021070)
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.


GoodfellaFD3S 03-26-08 08:24 AM


Originally Posted by slayerx7 (Post 8020982)
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.

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.

rollingsband1 03-26-08 10:06 AM

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 :-)

Speed of light 03-26-08 10:30 AM

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).

rash_rvg 03-27-08 04:51 AM

why not BNR 3 + AI? :D


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