single versus twin turbos systems
 

I was hoping to get some opinions on the twin sequential turbo system in comparison to converting to a single turbo system. I'm a potential FD owner, and have driven both twin and single cars, but never had a chance to drive them hard, nor would I say they were particularly good examples.

The things I am looking for in the engine:
-very good reliability
-excellent throttle response
-wide, usable powerband, suitable for autox
-peak power not as important as power delivery. Still I would expect to see something north of 300 rwhp.
-(at this point lets pretend that cost is not so important)

I don't think the unmodifed stock system will meet these goals. So given the choice between modifying the stock system (or completely replacing it but retaining the twin sequential design) or replacement with a single turbo, for meetings goals, what would be best? What is the ideal turbo setup for a car that is to be driven on the track and in autox, but still driven on the street, and must be reliable enough to be driven daily and on moderate trips?

a 35r with a small hot side is pretty hard to beat for the fun factor.

The stock system does very well on 4 of the 5. The first one is the only one it's not known for, but if you invest $500 in new couplers, check valves, some new solenoids, silicone hose, and a manual boost controller, I think you'll have that fairly well licked too. It's got a much wider powerband than any single and it's as responsive as any single too.

IMO, you'll find a lot of people biased toward single setups since 1) they've never actually sat down and attempted to learn/work with the twin turbo setup, and 2) once you empty your wallet for a single, it's only natural to assume it's the best.

Dave

A two words can solve all your questions. "Personal Preference"
The guys running twins (non-seq or seq) love them for low end pull and relative cheaper way from getting a more power (running non-seq).
Where as the guys running singles, love them for their simplified vaccum lines and bigger housepower gains.
Or if you are feeling frisky, a custom GT28 twins might be to your liking that has been done by one or two of the members here. Hybrid twins like BNR's stage3. Engine swaps to 13BRE, 20B, 26b(heaven :roll: ) or (shudder to think)LS1s.The possiblities are limited by yourself....... and your wallet :P :D
May be the RX 7 is not for you. Maybe a turboed-up S2000 or Z06 is more for you. But for some of us, The 7 is the car. Some might say the only car for them.

You will know when you are a rotary nutter like me when almost every engine bay you see, you think "Mm....20B or 26B could fit in there easy". That was i thought of when i saw the BMW M3 GTR's engine bay ..Haha..

I was wondering if anyone was doing that. I'd have to imagine that with two smaller modern turbos and ECU that the response is even better. Has anyone played with Mazda's "blackbox" vacuum line replacement that they switched to in 99 for the JDM market?

I have thought about an LS1 swap, as well as a C5 or C6 Z06, but while the Chevy iron makes ridiculous hp via its ridiculous displacement, it doesn't have the same feel as a rotary, and the Corvettes lack the style and nimbleness of Mazda's. I currently have an RX-8 and an NA Miata, but the FD has always been the one 'out there.'

One answer: The 500R.

I'll post as one of those who loves his stock twin setup. Of course i have all the bolt on mods that help the twins give you that real grunt you're looking for, and at ~320 at the wheel, along with the 'right now' response...i can say that it's pretty hard to beat. I also have the recommended upgrades like silicone hose and all that stuff that really make the stock setup reliable, but that being said, they really haven't given me one bit of trouble. Of course one day i'd like to swap out and get a smallish single to simplify and get rid of that annoying primary to secondary turbo transition...but i'm in no hurry and am enjoying my current setup tremendously.

Being a former muscle car guy (restored '69 and late model Camaros) i'm very happy with the performance of this engine. Sure you miss the raw torque and linear powerband, but it more than makes up for it with the grin factor, looks, and handling. This car really does have it all.

im with Efini on this one. i love the stock twins and i dont even have all the bolt ons. thats what im looking forward too. coincadentally* my first car was a 69 camaro, loved that thing(the only way i got girls haha) abd it was a beast i tell you but not nearly as much fun as my FD. i dont think i'll ever go single, i'll switch to BNR's and if i have a huge problem with the twins i'll switch to non-seq

I used to live in Cincy and worked at UC.
Anyhow, I think there is an rx7 club up there and they are pretty helpful.

Regarding to your question.. I'm a fan of twins.. You also don't need the 99 box. Just go simplified seq set up. It works fine. Most people on this forum went single because they exhausted themselves messing around with seq. set up. I myself have dealt with the problems of seq set up. But I still love the response of twins vs. single. And since you are not shooting for big numbers, I would stick to twins.

I like the twin set up so much, I have 4 addition sets at home.. just in case. And my new engine will have BNR twins.