I have yet to get the car dyno'ed. I've been scheduled twice, but had some bad luck. First time, they broke the brake drums on the dyno. Second time, the owner's good friend chewed up our time slot. I'm running on some street tuning based off of knock sensor readings .... with WAY rich fuel maps to be safe. Really need to get dyno-tuned and eek out that extra 10-15HP down low. I'll post a dyno sheet once I get time ... and a little cash. Racing season is in full swing .... no money.

 

My feeling is that this is exactly why you are trapping 125 mph (and John) while a lot of pump gas T-78s are doing 117-120mph. Peaks are nearly the same, but look at the difference in area!

 

I know if I raced a Mustang GT from a 3K rpm roll I would pull. My primary turbo is a monster at 15-16 psi - I have 12 psi by 2500 rpms and a full 15-16 psi by 2800 rpms. Bryan made my Stage 2s for spooling and low-end power and slightly less high-end power. To me, there is no FD equal to a sequential upgraded twin powered FD. I know single turbo cars move, but only on the highway. I may not have incredible tire squeeling top end power, but I was still able to pull 380 rwhp at 15 psi.

I know you could run the BNR Stage 3s sequentially but doubt it would spool that much faster - the Stage 2s I have spool incrediblely fast for not being BB like the M2s. Like I said earlier and like others have stated, an upgraded twin car is more fun to drive around town, on mountain roads and from low rpms pulls. Larger single turbo FDs are monsters from 90+ on but the powerbands seem to sharp for town driving. Lag, lag, lag, orbit. Sequential twins have a much more controllable and fun powerband.

 

On a stock FD, making the 1-2 shift (biggest drop) at 7500 puts you at 4350. 8000 gives 4640. But you're right about one thing: the low-end response only matters for the first gear you start your pull in.

So, here's a question for the single guys. Suppose you're rolling along at 2000 rpm in 2nd when you go WOT. What rpm do your tires break loose?

 

Going WOT at 2K rpms in a single FD - lol, you'd probably stall. In a T78 FD that I'm familiar with, he doesn't get full boost until 4700 rpms (18 psi) - but at 4K rpms, the tires kick out.

Kinda weird, my car feels like it has AWD because I can maintain traction at the top of second and all of 3rd - probably the heavy *** chrome 18 inch rims with Nitto 555s - not the greatest tire for handling, but the car maintains traction a lot better than when I had my stock 16s

 

This is so confusing. There must have been 15 different turbo models and setups mentioned in here. Am I getting the right impression that the Apexi RX6 is the best all around turbo? If I'm daily driving the car but still want enough power to walk some modded V8 domestics.

 

I'm waiting for someone to run the knight sports rf420 twins! Not holding my breath though.

While I'm not surprised the 98- spec turbos are becoming a common upgrade, I'd be surprised if people were silly enough to swap out a perfectly good set of their original twins.

 

I'm running non-seq w/ flapper door wired open but still in manifold. TCA set to closed.

Seriously, I cannot see why people are bitching and moaning about lag. There is increased lag, surely, but it is not even an issue. You can pass any car on the road in 5th gear - so that's not an issue. Plus the power is still unusable at max boost in 1st and almost all of 2nd anyways.

I'm not getting it. Do you guys want instant power before you even think of touching the throttle?

Once again: There is no free lunch.

You lose with SEQ when the transition happens. You have to utilize energy (in the form of heat) to pre-spool the 2nd turbo. There's no way around that. Non-seq essentially just slides the "pay for it" period to the front of the curve. The torque curve is smooth and predictable.

 

Apparently a lot of the die-hard Seq-4-life guys have a problem with downshifting.

 

Are you new around here?

 

what's your point?

 

I was referring to 91-98 twins vs 98- BTW. I can totally understand a twin --> single upgrade, though not something I'd personally want out of an rx7 (until I experience the 'perfect' streetable single)

 

I was just referring to your questioning of people being "silly enough" - that's all.

 

then, I agree whole-heartedly

 

On the flip side of the people who go single and want the twins back, there seem to be more people who go single and want a bigger single to replace it.

-Max

 

Updated numbers for folks interested in what stock '99 Japan-spec SEQUENTIAL twins make on the dyno.

Rx7 Store Tuning session 6-Mar-2004. Jason Baughman and Zavier Neeley used their FC Datalogit and Mustang Dyno (calibrated to yield DynoJet Chassis Dyno numbers). I didn't post the dyno graph--Jason and Zavier can back up my claims.

Brief mods description: KDR streetport, '99 Efini J-spec twins, '99 Efini y-pipe, GReddy 2-row FMIC, GReddy Airinx, DP/MP/RB duals, fuel system upgrades, HKS Twin Power/Magnecor Racewires, Power FC, RP underdrive pulley, Koyo rad, and bunch of other stuff I can't remember right now LOL

370.9 rwhp @7000 rpm
304.7 lb-ft @5750 rpm

AIT: 35 C (95 F)
WT: 84 C (183 F)
AFR WOT @ high rpm: 10.9 to 11.1
Boost: 16 psi
Fuel: 93 unleaded
Power FC target boost setting: 1.05 kg/cm^2 (15 psi) pr/sc, 70% precontrol/wastegate base duty cycles

On the road with ambient temps of 55-ish, the AIT dropped to 22 C (72 F), and my butt-dyno estimates at least 380-385 rwhp @ 15 psi.

The J-specs have absolutely spoiled me on the road. The 15-psi boost setting means, I can be gentle with the throttle inputs, and 10 psi is easily made @ part throttle, and low rpms; if a Z06 driver decides my car is merely a rice-burner--well--WOT @ 15 psi, will leave him scratching his head LOL

I'd never consider going with a single turbo, especially now that my peak rwhp isn't that far away from most single turbo peak rwhp numbers (radkins: 435 rwhp @15 psi, T04S, Pineapple raceport).

Whichever way you choose, enjoy! These cars are amazing when thoughtfully modified!

 

haha...This is true.

 

Someone above asked what happend when a single punchs it at 2k rpms. Not much, or alteast in my case. But my 2,500 is starts pulling, and around 3,500 it starts spinning the tires. At 4,500 the tires are pretty much roasting. Thats what a single and stock rubber size is like.

I have'nt had my car tuned yet, but my SR stage II feels like my old non-seq car. But its hard to realy say, as I don't drive my FD but couple a thousand or two miles a year. CJ

 

It IS an issue for some of us. Besides, once you are on the track, the computer keeps you in non-sequential anyway. But on the street, you get much better response below 3500 rpm.

Seriously, I cannot see why people don't like more low end torque....

 

I really liked the low down torque on the stock twins when running around stock boost, but once you turn it up it becomes a joke IMHO. I found that as soon as there was any moisture on the ground 2nd gear from 2.5k onwards was a waste of time as it just broke traction at anything approaching half throttle. Having not driven my car for a few weeks I took it out on a cool damp evening and at 45mph anything beyond light throttle in 3rd caused the back end to step out (which came as a surprise to me). Mind you having a passenger out in the car and having the rear wheels spin from 45-100mph without changing gear does produce a grin if you can watch the passengers face

Granted I stay in the wettest place on the planet so not everyone has this problem, and I did enjoy it when conditions were dry, but for my road use the stock twins were verging on dangerous.

 

Went ahead and created another thread with videos...

https://www.rx7club.com/showthread.p...hreadid=280389

 

That's not a good test unless we can get everyone to have the same size tires/wheels/tire brand.

FWIW, I can spin the stock tires in 3rd gear at 4500~ rpms(full boost comes on by 5000 and shifting at 9000 rpms) by starting at 2000 rpms and CONTINUE spinning them to my redline...

 

I have never driven/riden a singled rx7 that I thought was missing anything compared to a stock car. I'll drive my single in traffic, on the highway, and track long before I would go back to twins.

And I have been in at least 10-12 singled rx7's.

On the other hand the last 2 stock rx7's I've driven I couldnt stand it because the performance is so much less than I am used to now.

I have never been in a high-boost twins fd so I cant say for sure I am not missing anything.

Anyone who complains about lag in a single FD has never been in a singled FD.

Shawn

 

This is sounding like the FMIC vs SMIC debate. Choose without remorse, and enjoy the car already--Jeez!

 

what about the race gas singles? a twin cant touch that... i know its not a daily driver setup but i can run my 15 psi all week long on a single and dump my c16 in on race day... best of both worlds

stock sequential lack of lag is unbeatable but their are always sacrifices for big power.