Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

Opinions wanted 13b na or turbo for endurance racing

Race Car Tech Discuss anything related to road racing and auto X.

Opinions wanted 13b na or turbo for endurance racing

Old 11-05-14, 10:43 AM
  #1  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2012
Location: Chicago
Posts: 215
Likes: 0
Received 0 Likes on 0 Posts
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.
Diver22 is offline  
Old 11-06-14, 09:02 AM
  #2  
Rotary Freak
 
23Racer's Avatar
 
Join Date: Jul 2003
Location: Oakville, Ontario
Posts: 2,192
Likes: 0
Received 3 Likes on 3 Posts
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
23Racer is offline  
Old 11-06-14, 09:35 AM
  #3  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2012
Location: Chicago
Posts: 215
Likes: 0
Received 0 Likes on 0 Posts
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.
Diver22 is offline  
Old 11-06-14, 11:21 AM
  #4  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,576
Likes: 0
Received 123 Likes on 112 Posts
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.
j9fd3s is online now  
Old 11-06-14, 11:58 AM
  #5  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2012
Location: Chicago
Posts: 215
Likes: 0
Received 0 Likes on 0 Posts
787b? Not familiar. How about a half bridge?
Diver22 is offline  
Old 11-06-14, 12:34 PM
  #6  
GET OFF MY LAWN
10 Year Member
iTrader: (1)
 
jgrewe's Avatar
 
Join Date: Feb 2005
Location: Fla.
Posts: 2,838
Likes: 0
Received 0 Likes on 0 Posts
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
jgrewe is offline  
Old 11-08-14, 02:37 PM
  #7  
Rotary Enthusiast
 
Join Date: Jun 2005
Location: sydney
Posts: 966
Received 26 Likes on 24 Posts
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.
billyboy is offline  
Old 11-09-14, 03:41 PM
  #8  
Senior Member
 
Join Date: Jan 2006
Location: nanaimo
Posts: 428
Likes: 0
Received 5 Likes on 5 Posts
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.
racingdriver is offline  
Old 11-10-14, 07:27 AM
  #9  
Rotary Freak
 
23Racer's Avatar
 
Join Date: Jul 2003
Location: Oakville, Ontario
Posts: 2,192
Likes: 0
Received 3 Likes on 3 Posts
Originally Posted by racingdriver View Post
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
23Racer is offline  
Old 11-10-14, 09:27 AM
  #10  
Full Member
Thread Starter
iTrader: (1)
 
Join Date: Aug 2012
Location: Chicago
Posts: 215
Likes: 0
Received 0 Likes on 0 Posts
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.
Diver22 is offline  
Old 11-14-14, 11:50 PM
  #11  
Senior Member
 
Join Date: Jan 2006
Location: nanaimo
Posts: 428
Likes: 0
Received 5 Likes on 5 Posts
Here are some road racing rotaries. Lots of maintenance required to run at this pace!

racingdriver is offline  
Old 11-16-14, 12:01 PM
  #12  
Death to Infinite Scroll
 
peejay's Avatar
 
Join Date: May 2001
Location: Cleveland, Ohio, USA
Posts: 11,700
Received 43 Likes on 40 Posts
Originally Posted by billyboy View Post
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.
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...
peejay is offline  
Old 11-25-14, 02:40 PM
  #13  
Let's get silly...
iTrader: (7)
 
RockLobster's Avatar
 
Join Date: May 2004
Location: Rosemount, MN
Posts: 1,703
Likes: 0
Received 3 Likes on 3 Posts
road racing a turbo rotary successfully is CUBIC dollars over N/A
RockLobster is offline  
Old 11-25-14, 02:55 PM
  #14  
501 WHP Club
iTrader: (18)
 
Sammy Built's Avatar
 
Join Date: Feb 2008
Location: England, UK
Posts: 480
Received 4 Likes on 4 Posts
Originally Posted by Diver22 View Post
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.
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.
Sammy Built is offline  
Old 11-25-14, 02:58 PM
  #15  
Full Member
 
Join Date: Sep 2013
Location: asheville
Posts: 239
Likes: 0
Received 2 Likes on 2 Posts
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.

Name:  IMG_20140621_174531_zpsihfxtba6.jpg
Views: 124
Size:  140.3 KB


Name:  IMG_20141103_194417_zpsaxnpupd5.jpg
Views: 135
Size:  77.1 KB

Name:  IMG_20141021_191946_zpsdwbirx6t.jpg
Views: 132
Size:  91.3 KB
mhr650 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
dkwasherexd
Single Turbo RX-7's
21
05-27-17 04:51 AM
ChrisRX8PR
Single Turbo RX-7's
18
08-21-15 01:56 PM


Thread Tools
Search this Thread
Quick Reply: Opinions wanted 13b na or turbo for endurance racing


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: