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Single or twins for road course and autocross racing

Old 07-31-12, 11:47 AM
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Single or twins for road course and autocross racing

I am sure this came up out there but a search found nothing. Still trying to figure out the search function.

Would like some input form actual track set ups. Want to know if I should plan for a single turbo or set up the twins non seq on my FD for track use. Have done a non seq. set up on previous FD and liked it. Have not driven a single turbo set up.

Any input is appreciated.
Old 08-01-12, 03:45 PM
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I would got with the stock twins for road racing an autocross.
Old 03-03-13, 11:43 PM
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twins. a single large turbo takes longer to spool up than two small chargers. and in most cases you can match those two small chargers to get the same output as the large single without having any lag.
Old 03-29-13, 08:26 PM
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I would run a single turbo set up. Here's why
Going single makes the engine bay less complex, you get rid of a whole lot of vaccum hoses. There are lots of good turbos that will spool nearly as fast the stock twins. Gt35r is one example. This turbo will make you power all the way to redline. The stocks twins are more prone to fail, especially the stocker that are atleast 10years old. I would personally go single, it more expensive this route, but you can have a reliable rotary.
Old 03-29-13, 09:01 PM
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I own a single turbo set up and love it to death. But if I had functioning stock TT's that weren't blowing oil everywhere I would use those up till they are gone. Then I would switch to a single turbo.

Mine were blowing oil into the intercooler piping and I am up in the mountains so I opted to go the single turbo route.

I have a GT3574R which does very well. I think this turbo spools faster and better than my non-sequential TT set up and makes a lot more power.

It's also a lot more simple under the hood.
Old 03-29-13, 09:02 PM
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The twins arent great for the track due to their complex, fragile, hot nature. You'd do better with a tried and true single setup.

You don't have to go nuts. Get a cast manifold and a proven turbo. It will work every time.
Old 09-06-13, 02:58 AM
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single. twins are fun, but they are problematic. theorycrafting is different then being broken down at the track.
Old 04-30-14, 12:54 PM
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IMO I would think to go with the stock sequential setup. Although some singles (such as the GT35) have pretty good response, I still feel the stock turbos have exceptional response which would be really good especially for a tight nit course like an autocross. There are plenty of single setups that will produce good power compared to the stock twins but there are also different ways to create substantial power like upgrading the intake and exhaust, a higher performance intercooler setup. I agree the stock twins are very complex and are prone to failure, so the reliability aspect of a single can be a plus. I also think apart from spending money on adding power, why not decrease the weight of the car by removing stuff not necessary for auto-x? It's free!
Old 06-06-14, 12:18 PM
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small single for good spool , and less heat . small modern BB singles spool as quick as the twins with better torque /power quicker .
Old 06-06-14, 12:45 PM
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Both work. It's a question of how well engineered your setup is. Single turbo setups often result in cracked manifolds (search Fritz Flynn's posts), fasteners that loosen quickly due to the heat cycles - search CrispyRX7's ? posts.

Never really had a problem with my sequential twins and track days. Once they work, they stay working.
Old 06-13-14, 01:20 AM
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I'm sure if you took the peak hp potential of the stock twins and got a twin entry ball bearing turbo that peaks the same, you would have better response with the single. twin entry is pretty much like twin turbos, but you just have to figure how big. Most people on the forum talk about 400hp+ single turbos, and journal bearing being the most affordable
Old 07-10-14, 07:37 PM
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You need to know what kind of racing you're going to be doing. For me I'm planning on running TTB in NASA Time Trial races and upgrading anything will add points to my car and bump me out of my category.
Old 03-11-15, 02:44 AM
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I have ran both sequential twins and a GT35R in an autocross setting. I would go with the Single personally. Granted, each has their advantages. The twins have a lot better transient response. I notice myself getting onto throttle with the single a few moments before I would have done with the twins in the same situation so I am on power at the exit of the corner. One thing that I have noticed being a downfall of the twins mainly on slick autocross courses, like Royal Purple Raceway here in Houston, is the transition can really throw your car out of line even going in a straight line. I have been in situations where the car decided to get very loose going straight. Overall, the response is very similar between a 35r and the twins and you will have a more consistent and linear power curve with the single. Much easier to control at all rpm ranges.

Going on the reliability part. I would regularly see the high 90s in autocross with the twins after runs, maybe low 100sC in water temps. Ever since I changed to the single turbo, I have never seen anything over 94C. Also much easier to work on with the single, very few vacuum lines. I have falling asleep writing this so I am going to get some shut eye and I'll finish this tomorrow.

Good luck in your research!
Robert
Old 03-17-15, 08:28 PM
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I know this is an old thread but what about the BNR stage 3's. My FD setup is to shoot for 350 - 375 rwhp with BNR's, plus water injection and a Power FC. Car will see track days, Auto X, and some trips up to DGRR and the Smoky Mtns. Going single has been gnawing at me though, especially considering this Florida heat.
Old 03-25-15, 10:08 PM
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IMO single with the Borgwarner efr 8374 iwg. Why do I say that simplicity, great transient response, and doesn't choke the exhaust side like the twins. Power side it is geared more towards the 25 psi range of boost so will want race fuel or e95 to get the best use out of it, and it will make a lot more torque than you are used to in a rotary. For autocross you may even think about the 7640 it spools just driving through the parking lot light load.
Old 03-29-15, 06:35 PM
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Old 03-30-15, 09:18 AM
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I agree with the majority here, a well engineered single should win 7/10 times vs seq turbos. The seq turbos are great for DDing, coming from a light etc. but anything after 3k rpms a good single like an efr should be just as good and even better as the rpms increase.
Old 03-30-15, 10:07 AM
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I have twins in my fd and I autox a lot, I have never had any issue at all. If you set it up right it with a proper intercooler etc, it will be a rock solid set up
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