That's a silly statement. I've talked to a few single owners that hated the lag but dealt with it to get the top-end power. Truly honest single owners have always admitted that the lag is a trade-off for more power (like XSTransams post above).

As far as going back, I also know a few single owners who went back to twins, my mechanic included. My mechanic had a full T78 setup and eventually went back to the twins (99+) because they were more fun in all-around driving.

 

I should have qualified my statement to not include the t-78 or bigger turbos. I even thought about it when I was typing that post but never got around to typing it...

Have you driven a singled FD rynberg?

Shawn

Oh, and I have to make a silly statement from time to time so no one will take me to seriously...

 

Nope, I've ridden in a T04 car. Noticeably poorer low end than the twins but it certainly pulled nice after 3500 rpm. It felt progressive (ie, controllable) as well.

Haha, when I try to do that, people just think I'm being an *******...

 

You can run 15 psi on 93 pump gas. Race gas enriches the AFR (lower AFRs), so if you're interested in supporting 20 to 25 psi boost, race gas makes sense. FWIW, my Power FC is set to 1.05 kg/cm^2 for street, so yeah, 15 psi all the time...ready to shut down anything...(smack talk aimed at V8s).

I've ridden in Kyle Bacon's GT35/40 with Pineapple raceport. Damned quick car on the interstates. No way my '99 J-spec twins could hang from 60 to 160 mph.

FD owners that stay with sequential twins, are aware that single turbos have greater power potential (it's no secret, folks). It's really a matter of preference. Sequential twin owners like usable torque @ 2800 rpm ('99 J-specs). What's there to argue?

 

what about this dyno?https://www.rx7club.com/single-turbo-rx-7s-23/gt3540-dyno-sheet-179190/
this 3540 isnt really getting blown away by the twins...?

the rx6 is definitely running the highest boost and is very impressive, but how high could i boost with 93? and with 98? and with race gas? and it would still be effecient?

im having trouble deciding on bnr stage 3s, rx6, 35r, 40r. i just want the fastest turbo that can still autox pretty well. would the larger singles, 35r, 40r, be too laggy?

and how about those new apexis? imamura was drifting with a single.

so many questions. im confused!

 

My '99 twins made 370.9 rwhp, 304.7 lb-ft @ 5750 rpm, @16 psi boost, on 93 unleaded with AFRs between 10.9 and 11.1 @ WOT 7000 rpm (posted this info on page 1).

If you plan to autocross, go with the '99 Japan Spec Type RS/RZ sequential twin turbos. The lag from GT35/40 or Rx6 singles will render you uncompetitive in tight, short courses.

 

"and how about those new apexis? imamura was drifting with a single."

running an AX75F92@1.2kg/cm (around 500hp@6500rpm). I was more surprised to discover that car has a NOS bottle in the back.

anyway, back to the topic at hand...

 

how much boost can you run and not be killing the 99s?

when i talked to the bnr guy a while back he said something like the new stage 3s were capable of 450 at 18psi, which they are able to run. are there any results, dyno for that yet?

 

My Power FC is set to 1.05 kg/cm^2 (15-16 psi), pr/sc, 70% base duty cycles. I'm spoiled by this much power, and love using it when the need arises (otherwise what's the point of modding if you want to run stock boost most of the time??).

 

BNRs have had quality issues with oil leaks and such. I'm told the current runs of BNRs are much better. You'll get better top end power with BNRs, but their larger Mitsubishi wheels will not give you the low-end torque you get from smaller Hitachi '99 J-spec blades, nor their efficiency ('99 twins use an abradable seal that results in zero tolerance between housing and blade). There's no substitue for brand new turbos. Your BNRs will only be as good as the core it was built from (although I here most of the BNR turbos parts are new except for the manifold portion).

 

I'm not so sure about the low end tq comparison. If your basing that off my dyno you need to factor in that I didnt tune and was super rich up to 4500rpms. This is why my line sags at low rpms.

BTW - Your correct the new BNR's are 100% new inside.

STEPHEN

 

The sequential manifold is a bad idea from a reliability standpoint.

1. It weighs a ton.
2. It has bad heat dissipation.
3. It's a great heat sink.
4. Not the best flow design.
5. IMO, responsible for more o-ring related failures than anything else. It cooks them for dinner.

Single turbo is The Way.

 

Single might be the way if you can keep from blowing the motor on the dyno, while shooting for 550 rwhp LOL It's crazy. There are two Mk IV Supras in my town that put out 750 rwhp, so single turbo won't help you with trying to run with them LOL

https://www.rx7club.com/showthread.p...59#post2759459

 

Yes. But single turbo will keep my FD more alive on the track after continuous high rpm operation more than a seq setup will. A single turbo works *less* to produce the same results as the twins do. The overall heat is lower, the efficiency is higher, and the longevity is extended.

Both you and I are shooting for track application anyways.

 

Yeah, tracked my stock twins for 7 years before the water seal failed (10 years, 102,543 miles). Have not driven a single turbo FD on track, so I cannot comment on that. I drive my FD daily, so a single turbo is not the ideal application for me

 

If you had an RX6 or GT series I couldn't see you ever going back to SEQ after acclimating yourself to the single setup.

 

Ive never seen race gas enrich an afr... Just allowes you to run leaner afr's and more boost before detonation

 

The same can be said about people that complain about V8 conversion FDs have never been in a V8 conversion car.

Have you been in a V8 FD? I have.

https://www.rx7club.com/showthread.p...hreadid=280030

 

cool thread
joel

 

You are really tring to muddy the waters now.

I am not anti V-8 FD so you will find no arguement from me - but I bet you are sorry to hear that since you were probably looking to start a fight .

Shawn

 

I'm not trying to start a fight. Actually it is easier to see there is quite a difference in a twin car and single car at the lower rpms in power(via the link first posted up). I don't know how everyone else drives, but in my twin powered R1 I like to keep the revs as low as possible unless I'm racing. Keeping the engine revved up at 3500+ rpms just promotes poor mileage and more engine wear. That means I cruise through town at 2300 rpm or so. When I want to GO I don't want to shift down. Twins give me good power pretty much instantly (not V8 instantly).

All those dyno charts show cars at full throttle so that doesn't even show spool up time. It would be nice to data log throttle position vs. manifold pressure. I'd bet you'd find that the single cars don't spool as quickly when the throttle is applied. In a track environment that doesn't matter nearly as much. On the street and auto-x course it matters a lot.

Build the car for how you are going to use it, most guys just want big dyno queen HP and I guess the T-78 or whatever will get them there. The problem is you'll have to slip the clutch like crazy to get it to leave the stoplight with more than 50hp.

I've driven a single turbo rotary a lot, it was called a TII. In stock form the boost response SUCKS, leaving a light in the summer with the AC was downright embarassing. Putting on a full exhaust and intake made boost response pretty decent. Power was smooth and linear, predicitable, controlable, etc. That is a pretty small turbo though and it's bottom end hp was still worse than a stock FD and I noticed it on the auto-x course. On a track it would work well. My old TII now has 185K miles on the original motor...

 

Thanks for the very well worded post, Jeff. Sometimes I think that SleepR1, Artguy, and myself are the only ones who appreciate the sequential setup...

BTW, I wouldn't mind if you posted more detail regarding your auto-x experience with the V8 FD. Comments regarding turn-in feel, balance, etc. I realize that it wasn't your car, but anything is helpful. If I go through a couple of motors for some reason, the LS-1 (2?) will look a lot more attractive.

 

I think it just has to do with what your goals are. If you're into auto Xing, Jeff has it nailed down. But if you're like me and primarily drag race, then a nice sized single might be in order. I don't do much in town driving. Infact I avoid it. I don't run a front plate, and the windows in my FD are extremely dark. Its fairly loud, and its a cop magnet. Not to mention it has a open atmosphere wastegate. My wife and I enjoy driving around the country roads listening to music. Each person has their own taste, and I'm fine with that.....even V8 swaps. Would'nt it be boring if everyone was into the same thing?

This debate is as bad as the front mount vs stock mount. BTW, I like stock mount.

CJ

 

I have been in quite a few Single Turbo FD's and I like them alot better than twins. I have never ridden in a modified twin car but the power would have to be significanly increased for me to be impressed.

I have gotten used to the linear power curve and power on tap that my twins did not have. I don't miss them one little bit.

Chris

 

Okay why not flip this around to:

"Why is low-end response so damn important compared to mid-range and high-rpm?"

Some of us do NOT want to lug the engine around at sub 2500 rpm - flooring it when the need arises. That's not exactly easy on the car either, compared to cruising around at 3500 rpm.

I just do not see why the power loss in the mid-range, which you need quite often when on the throttle, is LESS important than low-end response, which you don't need all of the time.