Recently, I've been bit by the tuner bug pretty bad, and I've been spending time planning out a BNR or Single conversion for later down the line. While doing this I've had some questions come up that frankly probably couldn't be easily found anywhere else, so I'll just get started.

Not trying to start a huge debate here, but what would be the best option for making 350-400hp and still keeping the car streetable? I've found some dyno charts for BNR's that put their max output around 366hp @ 15psi, but I was looking for a little more than that for those *special* times when it might be needed, and as a result I've been looking at a GT35R with a .82 A/R. If anyone who's had experience with this kind of situation can chime in with suggestions it would be helpful.

Also, from looking at compressor maps, everything seems pretty self explanatory, but begs one huge question; what is the maximum airflow in CFM that a stock engine can take in? Anything I run I'd like to keep at 15PSI so I can get away with just some bored out secondaries, and if I feel the need to temporarily go higher, I'd have some AI attached to a toggle switch. That being said at 15PSI these compressor maps usually have a pretty wide range of airflow in lb/m that can be given to the engine, so the limiting capacity would be the engines breathing ability, so the question is, where is that limit on stock ports? on a streetport? assume a HFC and RB catback 3" all the way Feel free to chime in on that.

Also speaking of AI, does anyone know of a system that can detect low fluid level and automatically adjust boost and fuel accordingly? I have no doubt this exists, but I guess my main question is how well does it integrate with a PFC and EBC?

Those are all that come to mind, right this moment, but I know I'll be adding more as time goes on, and any help I can get from you folks is invaluable.

Thanks

 

depends which internet forum post you believe

 

If you want to make over 360rwhp on stock ports, you need a single turbo to do it unless your name is JD. You can see what ErnieT did years ago with a stock reman:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/pics-me-%40-track-my-10-sec-pass-128190/

 

I'm bias,... BNR's are my choice.

 

I just made 370whp with (sequential) BNR's about a month ago on have stock ports. Probably could have gone a little higher, but I was limited by fuel since I'm running 4x 850cc injectors.

 

Go with 99 twins, a large street ported motor, v- mount, 1300cc secondaries, supra tt pump and have ray and PFS tune it You should put down 350 plus at 14 psi no problem and have a great street hot rod.

 

And that will also depend on which dyno you use.

 

Of course, I don't disagree with you there at all However I doubt that PFS runs their dyno to boost customers reported power figures hehe.

Also, I think my numbers were a bit low because my engine may, sadly, be on it's way out =( I've noticed hot start issues and think they are due to compression numbers dropping =(

I think that with a healthy engine, and the right setup, members should certainly be able to get more than 360whp on stock ports Granted... it won't be cheap or easy though

 

About 3 weeks ago I made 343 @ 7 psi, and 391 @ 16 psi on very small street port and pump gas, my setup is full non seg, 550 primary, 1300 second and all the bolt on's, and the most important thing tunning matters allot, get the best tuner and u will get your goal.
Khris

 

Thanks for all the input folks, my ideal setup is changing by the day thanks to you guys, and its all good.

One thing I would like to stress though is that I am looking to keep it as streetable as reasonable with the option for a little extra. I have no honest problems with the BNR's but the main thing that has been holding me back from them is the whole keeping it simple thing. I'm DD my FD, and plan to after I finish all of the upgrades, so streetability and simplicity are king since at the moment I've got a 70 round trip commute to work, making huge dyno numbers is kinda on the back-burner, although having that extra power is kinda nice too.

Rx7aholic, I have to ask, what were your A/F numbers like? and that seems like a TON of power for even non-seq twins at that pressure. Maybe I need to search more though.

Fendamonkey, I did a search on some of your threads, and actually it seems like I'm looking for the same power output and driveability you are. Just out of curiosity, are you happy to have gone with BNR's, or do you think you would have been better off with a medium sized single with a quick spool?

 

99 spec twins are waste of money when there are units out there like the BNR's or the Knightsports twins and should only be considered if your looking for a stock replacement to run on your stock ECU and just want something new for reliability or whatever reason you may have. They provide no additional power but some claim they spool quicker (because the 93 twins are laggy I guess *sarcasm*)

I would suggest going single with something like a GT35R and a divided manifold and hotside. What A/R you choose would depend on if you want to have a little more top-end or quicker spool down low. A smaller A/R (0.82-0.86) is usually more fun to drive on the street but if you want to track the car or like going fast on the highway then a larger A/R (0.96-1.06) would be preferable since you'd make more power. If done and tuned right you will have a very enjoyable and fast car to drive. Now I should note going single does cost more since there's more things you need/have to do compared to a bolt-in replacement like the BNR's.

BNR's are a good modest upgrade but usually if your thinking about swapping turbo's, its because you want a power boost and possibly added reliability. The BNR's do give you a power boost and don't blow up past 14 PSi (exaggeration). When going single you get rid of the rats nest which is a headache for quite a few people when something goes wrong, especially those running sequential (there is nothing wrong with sequential and I actually quite enjoy them, just has a higher maintenance demand on a 20 year old car) and your removing the twin ovens which are the cause of a lot of engine bay heat. So in affect you are improving reliability by going single even though you have more power.

Also, when reading about expected power numbers with given setups on this forum, it is very important to understand that EVERY dyno will read different even between the same models. So don't take given numbers as what you will get but a general idea. You can put the same car on 2 different dyno's and one will read 330 rwhp and the other 370 rwhp. Which number is right, it doesn't really matter. A dyno is a tuning device and not an accurate measuring device of power unless your comparing cars on the exact same dyno. But keep in mind things like the weather affect the dyno's readings too.

And one final note, going single makes your car slightly louder then twins since you lose the muffler affect the twins provide. This is something most people don't think about and it really depends on if you care about it or not

*the reason I bracketed those a/r's is because usually those are the 2 choices you have to choose between (that you should be choosing for your setup anyway)

thewird

 

I made 421 rwhp at ~17.5 psi on non-seq BNRs over four years ago, this is nothing new

https://www.rx7club.com/time-slips-dyno-121/video-bnr-stage-3-dynapack-results-509445/

If you want to keep it simple then consider BNRs or 99 spec twins because they bolt up and go. BNRs if you want more power, 99s if you want stock power. Also, this subject has been beaten to death over and over again, there are many topics like it over the years.

 

I am certainly pleased that I chose to go with the BNR's. Will I always keep them? Who knows.. I'm getting a sinking feeling that my engine may finally be on her way out (compression dropped after ~ 50k miles) and my plan has always been to get a nice streetport and go with a good single when I rebuild. To be honest though, I don't think I'm done with the BNR's just yet ;-)

Given that I see a rebuild in the near future, and I've always planned on going single with my rebuild, I can honestly say that I think I'm going to choose the BNR's over the Single yet again.

 

My 2 cents:

First, Rich's BNR numbers were with a ported motor, so non-stock ports (so don't expect 400rwhp on BNR with stock ports). Next, IMO, BNR's are only a useful upgrade if:

* You want to keep the sequential turbo operation
* You live in California and need to not have the inspection ****'s hassle you

If you don't fall into either of those, just upgrade to a single turbo and call it a day.

 

The stainless steel single turbo manifolds can be difficult to seal, exhaust leaks are fairly common. Cast iron manifolds doesn't have these issues. Either way, you're not talking about a huge diff in power between a medium single and BNRs, and 350-400 is plenty for the street.

Wonder what was cause this? Interesting how some engines tend to lose compression faster.

 

But Rich, this is the joy of the third gen section for each new wave of owners Read Ecclesiastes 1 sometime - "all is vanity"

 

sorry goodfella, my search-foo is weak

Thanks all for the help, and I think I have a good idea of where I'll head now. If anyone thinks of anything that might have been missed go ahead and jump in, but I think I've got everything I need.

 

Goin single?

 

yeah, GT35R w/ divided mani and hotside .82 A/R I may loose out on the high end, but I'll have the power in the low end where I would need it most, and if I want to change things later, I can probably swap out the turbine housing for something larger w/o too much trouble.

I like the seq BNR's, but I really want to make the car as simple and reliable as possible.

 

I may consider selling my non-sequentials w/ fully ported manifold for a good price

 

ah no thanks man, my sequentials are still working pretty nice for now, and its gonna be a while before I get started on the single build, so I'm saving for that. I'm actually trying to get rid of another set of sequentials that came with the JDM engine I put in. they look damn good, no oil leaks, and no cracks, with probably around 35k on them. So if you know if anyone looking for a good set of twins I'll let them go at a good price too.

 

Hey I also I forget that I still running my air pump setup with acv and hi-flow main cat, I believe if u have the right mods and tune I think u can make good 380 or more.
Khris