Opinions wanted 13b na or turbo for endurance racing
 

Am looking for a weigh in if the extra hp of the turbo will out do a na if you figure in extra pit stops. I am done for the season and want to see which way I should go this winter.

What do you mean by endurance racing? A 1 hour, a 3 hour, a 24 hour? The reason I ask is ignoring club rules, most higher hp Turbo cars I have seen try to race longer than 20 minute sprints struggle with heat control. The rads and oil coolers are always too small, the gearboxes require tons of coolers to stay alive and the rear diffs need coolers as well.

Also, the cars can really build up coolant temps very fast when they are under sustained loads while drafting other cars. As well, the turbo engines tend to be pretty finicky and can pop easier with a missed shift or poor fuel delivery when the cars get low on fuel and starve in corners for a second or two.

I am not saying it can't be done, I am just saying that I really haven't seem many turbo cars that have been a consistent threat for longer races and I go all the way back to Firehawk days when the Mazda factory was competing in TII FC's and trying to make them competitive.

I would really need to know the rules and intended performance goals as high HP NA cars are also fragile, but the can be made pretty durable easier.

Eric

We do the chumpcar and lemons races that range from 7-24 hrs. Our best so far was in April where we finished 13th out of 85 with a 12a. We were 6 seconds a lap behind the leaders. I just don't know if we do a street port 13b or 6-8 psi turbo 13b which would be better. I'd like to make 2-3 hrs between pit stops.

i wouldn't even try a turbo car for road racing, well more than a 20 minute session.

we ran a 6 port engine in ITS trim for a while, and it gets the same mileage as the 787B, but makes like half the power per rotor, so i would stay away from the 6 ports

it also would be tempting to go P port, as BSFC is better.

787b? Not familiar. How about a half bridge?

We run Miatas in ChumpCar because making a turbo RX7 last would be nearly impossible while keeping it under the value. Fuel mileage would suck too.

If you can sneak a 4 port 13B in the car with a street port that would get you the power and keep reliability. Never figured how it would hash out value-wise.

Also, good luck keeping street port quiet enough

Can be done with a FD, there's been 12 and 24hr runs here and OS within recent memory, but much higher probability of stuffing up. 2~3hr runs aren't a possibility unless you get a Dakar fuel cell! We don't see the engine oil/coolant issues mentioned with proper ducting and all, diff cooler would be mandatory, gearbox less so, but good to have.

One of the guys who posts here occasionally is running a 2~3hr race this weekend in a first gen BP - oh my ears - well developed compared to the IT(?) cars over there. It's probably 70~80hp down on an enduro FD and quite a bit less midrange, 250lbs lighter though and lap times better, although he is a local!

Of the 3 other rotaries present, only know 2, both FDs and out before qualifying was over.....I think there's a cautionary tale there. :lol:

NA would be better. save fuel, run pump gas, probably cheaper,

Turbo cars like high octane, a strong clutch, bigger brakes, , intercoolers, wastegates, high heat vacuum lines that need replacing all the time, turbo gaskets don't last long on roadrace turbo rotaries.more oil coolers, a big $$ rad, , stronger tranny, etc etc,

I roadrace a turbo 20b fd rx7 with 700 hp btw.

You would totally know. If you wouldn't run your car for 4 hours even after everything you have done to your setup and spared no expense, then I think we should stick a nail in this and say NA for endurance races, Turbo for Sprint races.

BTW, how is your car at hot restarts? Always wondered about the effects of heat soak after a 2 minute pitstop for refueling and tire replacement. Would the car run like crap until it cools down or would the excessive heat hurt the car some way on the restart? I know that with the Cobra R, it was like a locomotive and we could start and stop and restart that car every hour for 12 hours. I don't know if a 700 hp turbo rotary could do that.

Eric

Thank you everyone, I am going to go small port na. I have a bunch of turbo stuff that won't be used if anyone needs anything.

Here are some road racing rotaries. Lots of maintenance required to run at this pace!

Improved Touring is quite restrictive on what you can do. Stock porting, piston engines must have OE spec camshafts and compression and other such things, suspension is very limited, etc. It's more-or-less the place where old Showroom Stock cars retired to.

Showroom Stock meant just that. Even the roll cages had to be bolt-together units, because welded cages might add chassis stiffness, which could be a performance advantage...

road racing a turbo rotary successfully is CUBIC dollars over N/A

If your 6 seconds behind with a simple 12a setup. You have much more room to grow with a aggressive port and 13b transplant. I would say stay na but take it up a notch. Turbo rotary is expensive especially for the intentions you have.

With the 2015 ChumpCar rules on turbos it would be next to impossible to run a turbocharged first gen. the values for an add on turbo are completely exorbitant and the swap values to get a factory turbo motor in would never work. Kind of a shame since every member of our team is a turbo engineer….. a ported 13B can be pretty quick that is what we ran and never had a problem on the straights. We used a GSL-SE 13B, but I have a complete 86 second gen engine in my basement waiting to be built. We crashed the car at Summit point but we were able to find a new body that is way too nice to build into a ChumpCar but oh well it is looking pretty good so far.

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