Hey guys,

Long time reader, first time poster I'm in the process of getting rid of my evo (just waiting for the check to clear!) So, essentially I'm on the market for an FD come springtime, but trying to source/order parts while I don't have car/insurance payments.

Enough wasting time. I'd like to setup an FD for the track, and would like to keep the twin turbo setup. However, I've yet to find any recommendations on upgrades (yes I searched, but came up with nothing). Can anyone offer advice on this? I'm not looking for some insane numbers, I'd hope to hit the 350-450hp mark with all supporting mods. Any help is appreciated.

 

That's a big gap in power. You can easily achieve 350rwhp on the stock twins. For most people, that's a handful on the track.

IMO, I would stick with the stock twins for a while. If you are building a track car, you'll have more to upgrade other than the turbos.

 

Like Mahjik said, there are many many things you need to take care of before you think about upgrading the turbos (like buying the car just kidding.) To support 350+ hp, there are fuel mods, engine cooling, ECU upgrades, and lots of other things to consider.

That being said, if you want to retain the twin setup, the most widely used option is the BNR Stage 3 twins. They put down more than enough power for the track.

 

No doubt in my mind I'll need more This wouldn't be my first build, but first with track times in mind vs an aggressive street setup. I guess you could say I have the car mapped out overall in terms of suspension, aerodynamics, braking, fuel, safety, blah blah blah... there's just a few area's that I'm stuck on. Turbo's, are the main thing I realize I know nothing about. Looking at different sites and seeing the xx A/R, xx trim is almost another language to me.

The only issue I have with stock twins is lag, I'd prefer to go with something ball bearing (unless the lag isn't as bad as I have heard). When do they typically reach full boost?

Another reason I'd prefer to avoid them is if i'm not happy with 350rwhp, all it would take is higher boost, and a new tune. Or run separate maps for street driving vs aggressive. I have a feeling this will be the case once the build-up time comes.

 

The stock sequential system was design to combat lag. From the first turbo, you'll have full boost by 2000 rpms in sequential operation. Both turbos have full boost about 4500 rpms. There are no more ball bearing upgrades for the stock twins. There was only one company to offer that upgrade and they are no longer in business. There is a set of those for sale on the forum though if you want to go that route.

Honestly, for a road racing car, if you want more power you'll want a larger single turbo. Why? The more you push a turbo, the more heat it generates. Using a larger single turbo but under its peak efficency will reduce how hard you work the turbo, how much underhood temps you are creating as well as your charge temps.


Also, keep in mind that a ~350rwhp FD and a good driver can deal with C6 Vettes on road courses. Its a different car and doesn't require the monster HP numbers which other cars rely on....

 

Hmm. My understanding was large singles were used more for straight line / highway runs / dyno queens. I always worried that having a large single while taking a turn could spool faster than expected causing an unexpected loss of traction. Granted that throttle control will also play a big part, but I'd always prefer to be safe than sorry. If this isn't as big an issue as I think, maybe I will go the single route.

A buddy of mine in thailand recommended the hks t51r if I went single... but isn't that setup made for higher numbers? (ie, 600+?). I've also heard good things about the gt35r... I know these work wonders with evo's and 240s... but how do they fair on an FD? Would anyone recommend these over the BNR stage 3 that vegas recommended?

Sorry for the barrage of questions, but thanks for the great info

 

the apex rx6 turbo is prob a good idea for a single setup, IIRC it was designed to provide power at low rpm ranges over high hp numbers

 

I recommended the BNR's because you said you wanted to stick with the twins. If you go with a single, the GT35R is a great option. You could look into the A-Spec 500R. As far as the 51R, it's a quarter mile setup. Search the username "LUPE". He's running it.

 

IMO, I would not upgrade to "other" stock mounting twin turbos for road racing. Check the Corky Bell book as he has a whole section about why to run a larger turbo for road racing. I just basically paraphrased the whole thing but like I said you want reliability. Running a larger turbo (say something where you could boost it to 25 PSI) and running it lower (say 14 PSI) on the track will benefit your car all around. The key is getting a turbo that has the response time you like, has decent power in the lower to middle range where you plan to run it, and IMO rebuidable here in the USA (for use US people).

Is lag an issue? Sure a little. However, on a road course, you don't spend a lot of time in the lower rpms. That's basically one of the keys of being a good road racer is the ability to keep your car in its power range all around the course.

You should check the Single Turbo section on this forum. They'll have quite a bit of info on the various turbos people used/tried on RX-7s.

The problem is the Apexi turbo is not rebuildable here in the states. Also, if he wants to run the kind of power he's talking about, he'll be running the turbo on the upper end of its efficiency. That will generate more heat for charge temps as well as underhood temps which is something you want to avoid for longer track sessions.

 

so if someone wanted to run a single turbo for lets say autocross where the mid an high rpm's are usually maitained youd still want a turbo to be able to react at low rpms just in case.

so what im asking is what would be a good setup ie... boost controller, turbo, down pipe, etc....

 

Autoxing and road racing is something completely different. With autox, you won't be in the high end all of the time, the tracks are too tight for that. With road racing, we're talking about actual race tracks, not cone courses.

 

thank you, i did know that, but i was wondering what peoples opinions were for the weekend warrior

 

The Apexi RX6 turbo would be good single for that type of application. It delivers similar performance to the stock twins without the complexity of the twins.

 

it does provide more performane and tunabillity correct

 

becasue im also looking for performance, anything recommended to compliment it

 

Where is goodfella when you need him? hehe...

 

Single is alot easier way to go

 

I'm grumpy tonight so I am gonna say it: man you didn't search crap.

There is TONS of info in here covering the exact things that you have been asking. So far your q's have been very general so a quick search would bring up much more info than just creating a thread. Upgraded twins pros and cons?, singles too laggy?, what turbo(s) is better suited for my application?... It's all here.


Ok now that I busted your ***** here are some links:

https://www.rx7club.com/showthread.p...=single+choose

https://www.rx7club.com/showthread.p...=single+choose

https://www.rx7club.com/showthread.p...=single+choose

https://www.rx7club.com/spec-tuning-154/

https://www.rx7club.com/spec-tuning-154/gt35r-kits-ask-anything-relevant-35rs-kits-thread-465560/

 

Lol, mahjik definitely has this thread under control

Junon, click the dyno link in my sig. I was running BNRs in parallel, so they were laggy. BUT, you can run them in the stock sequential setup and have a killer powerband. At $2350 they're inexpensive, relatively speaking. You can make 400 rwhp, with 3000 to 8000 rpm power. I wish I would have run my BNRs sequentially, I would probably still have them on the car.

Otherwise, for your application I think the GT35R or 500R (35R variant with higher boost capability) are good choices. If you go much bigger (T-66/T04R/Greddy T-78/HKS T51R etc) then you are looking at more of a straight-line car with poor sub-4000 rpm spool, which won't realize it's potential without c16 race gas.

 

lol there you go problem solved