LittleCarp04

what options do you have to keep the twin setup?

i know about the 99 spec turbos, and the BNRs, but can you put 2 bigger (not huge though obviously) aftermarket turbos on it?

thanks for the help

VegasFD

People have done custom large twin setups before. But they require tons of fab work and expertise. Do a search, there are a few members who have successfully done it.

VegasFD

Here's one:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/my-twins-584134/

RE-Amemiya

I believe you can also do twin GT35R's.

I'm sure there's more as well.

rynberg

The only thing inherently great about the "twins" is the ability to run them sequentially. The only real upgrade to run this way is the BNR Stage 3s. Any other "twins" setup would be run non-sequentially.....

Upgrading the turbos should only be considered after all of the other mods are in place -- downpipe, midpipe, cat-back, intake, bigger IC, upgraded fuel system, standalone ecu.

Upgrayedd

iTrader: (1)

Isn't ASpec working on a twin ballbearing turbo set-up??

BLKTOPTRVL

Not so sure about that... If your stock twins are finished, and you are looking around for another option, this would be the time to get the 99 spec or the BNR or whatever else is available. Not having all those other mods is not a necessity.

VegasFD

True, but I would consider the upgrade of the turbos due to failure an extenuating circumstance. However, the upgrade of the turbos for strictly power gains should be done last, with all supporting mods done prior.

BLKTOPTRVL

Yes I agree with what you and Rynberg said whole-heartedly... I also think that Rynberg gives some of the best technical advice on this forum, but I see a lot of general questions asked here and a lot of answers provided in terms of absolutes, not concidering all the situations the user may have had in mind, but not voiced.

I just like to avoid absolutes when not necessary.

rynberg

BLKTOPTRVL, you are absolutely ( ) right. I was speaking in terms of "upgrading" only, and not replacing. However, if I was keeping the car close to stock and needed to replace the turbos, I'd probably try to find a good condition used set before dropping $2400...

BLKTOPTRVL

True, but in a case like mine...

If I knew my turbos were done, I would opt to buy the 99 spec or something better - as long as it will still work with a stock system. Then, if later I wanted to make further updates, I would already be ahead by one set of better turbos.

rotorypolo

iTrader: (1)

twin turbos are only good if you can wire them sequentially IMO. twice as much complications, twice as much stuff to go wrong, and twice as pricey....If you need more power then what BNRs can offer, just go single.

Recentlyconverted

does anyone know then what the potential for power the 99 specs and the bnr stage 3s have? also, isn't there the oil leaking issue with the bnrs?

BuffDaddy915

Petit Racing was said 2 have modified a set of twins...I have no clue about what they do but it was in a magazine.

Improved FD

not sure I agree with that, I believe properly set-up non-sequential twins can deliver a better spread of torque over a broder rpm range and deliver boost faster than a big single....Brian (BNR) made 400 ft-lbs of torque on his stage 2s

since converting to the stage 2s with stock exhaust wheels (and all supporting mods, incl light weight flywheel), the car spools essentially every bit as quick as the hopelessly complex stock set-up, even on the freeway, and, of course, is more powerful everywhere....overall it's a very user-friendly powerband

rynberg

I've never seen a dyno where non-sequential twins were at full bore before 3500 rpm. A GT35R T4 is at full spool by this time and has a bigger potential at lower boost levels. And doesn't have the restrictions of the stock manifold.

Just my opinion. If I didn't live in such a smog-**** state, I would likely have gone with the GT35R T4 instead of the Stage 3s. But I do, so I'm grateful Bryan makes these things.

Improved FD

the inspectors would bust you immediately if they saw an aftermarket turbo?

rynberg

In Cali, you have to pass a visual inspection before they'll even put you on the dyno for the actual emissions test. As most of us RX-7s are now being forced to go to "test only" stations, where the techs tend to be a little more car savvy, you are not going to get away with a single turbo, no matter how clean the install is.

You also just couldn't rig up an electric air pump to pass, like those in some states can get away with. You even have to have a working CEL to pass....so you have to do a little wiring trick to get the PFC to turn on the CEL at start-up.

swif

iTrader: (4)

What is the trick need for this^^^?

Improved FD

glad I don't have to mess with all that bs

here in NC, if the car is 10 years old or more, you don't have to pass emissions

of course, I still have MI plates on the car, anyway