Race durability of the N/A rotaries
Joined: Mar 2001
Posts: 31,835
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From: https://www2.mazda.com/en/100th/
Originally Posted by tims
I have run a turbo 13b, 13b peripheral port, and an E-production 13b(six port street port). the longest lasting motor was the turbo 13b. It was low boost and low revs it ran about 10 or eleven events over 2.5 years. PP motor lasted about 2.5 events(maybe 6 hours) before the bearings shredded. The first of 5 EP motors did not make one minute on track before it shredded the side seals. the other 4 lasted: 5 race hours plus 1 hour of dyno tuning, 1.5 race hours, 2 race hours plus 1 hour on dyno, 3 race hours plus 1/2 hour on dyno. All engines were built by local "rotary experts" with new parts. Professional and well respected rotary engine builders charge a very high premium for a high quality engine. One firend had a PP motor built by a very famous rotary racer and the final total was more than $10,000. For $10k I can have an 600hp dry sump V8 with money left over for the first freshening. My problem with the rotary engine in racing is a lack of good "semi pro" engine builders. In the piston engine world there are quite a few choices for good inexpensive engine builders for anything from Honda to chevy, but over the years the rotary connection have just dried up. there are alot of guys claiming to know everything there is about these engines, but I have yet to have any of them deliver. My problem is a lack of local talent and my inability to afford the real pro engine builders. Last year I paid more than $4000 for engine rebuilds, parts, and tuning. this excludes track time and expenses. Yes, I should have spent that upfront and got the good engine, but hind sight is 20/20 and I thought(wrong of course) that the supposed expert would deliver what he advertised.
i do agree though, the other local guys pay for thier engines and they are making more power than we were, but reliability is inconsistent.
basically though the inability of local builders to deliver is why i build my own engines in the first place. i'm not saying i'm doing any better but its my motor....
Senior Member
Joined: Sep 2002
Posts: 286
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From: Wandering the USA in my Winnebago
Originally Posted by tims
... The first of 5 EP motors did not make one minute on track before it shredded the side seals. the other 4 lasted: 5 race hours plus 1 hour of dyno tuning, 1.5 race hours, 2 race hours plus 1 hour on dyno, 3 race hours plus 1/2 hour on dyno. All engines were built by local "rotary experts" with new parts. ...
my $.02
Hi Tim,
Before having my 12a j-bridge built in 2002, I checked around the GT-2 / GT-3 scene and most guys were getting 11 hours (a full season) out of their motor before refreshening over winter break. Many times the refresh was just to inspect things with no major part replacement. Complete overhaul was not too common. Carbon apex seals lasted about 3 seasons and the ceramics show virtually no wear if motor is treated properly.
SOME guys in nor cal were having trouble making top power and getting longevity. It was one or the other for a while.
I talked to Evan and he had 40 hours on his 13b PP at the time with carbons and smaller endurance race size intake sleeves. Shifting around 9400 was the key for him. Of course it made power to 10 but they don't last as long up there.
The side seal issue in 6 port EP is the intake ports being made too big and the side seal grabs the port and gets destroyed.
Have you tried B&B Racing in nor cal? They make good rotormotors.
Brad
Before having my 12a j-bridge built in 2002, I checked around the GT-2 / GT-3 scene and most guys were getting 11 hours (a full season) out of their motor before refreshening over winter break. Many times the refresh was just to inspect things with no major part replacement. Complete overhaul was not too common. Carbon apex seals lasted about 3 seasons and the ceramics show virtually no wear if motor is treated properly.
SOME guys in nor cal were having trouble making top power and getting longevity. It was one or the other for a while.
I talked to Evan and he had 40 hours on his 13b PP at the time with carbons and smaller endurance race size intake sleeves. Shifting around 9400 was the key for him. Of course it made power to 10 but they don't last as long up there.
The side seal issue in 6 port EP is the intake ports being made too big and the side seal grabs the port and gets destroyed.
Have you tried B&B Racing in nor cal? They make good rotormotors.
Brad
Rotary Enthusiast
Joined: Apr 2001
Posts: 1,289
Likes: 0
From: North Hollywood, Ca USA
Thanks for the referral. I am done with garage built engines for a while, unless as another poster suggested I do it myself. I may be out of the mazda race cars soon anyways. I have a new race car that I may concentrate on for the time being. I know a couple real good pro engine builders but the cost is just to high. As for the treatment of parts and engines. Parts were the responsibility of the builder. I didn't watch the guy put it together so I can't say what he might or might not have done. As for the treatment of the engine once installed. They were never overheated and all were dyno tuned before any laps at the track were run. All were equipt with EGT gauges and showed no problems, except lose of power and eventually no compression. Low revs is the only way to make them last in my opinion.
paradox
Joined: Oct 2002
Posts: 1,296
Likes: 2
From: SoCal
I have used nothing else but stock original engines. My first GSL-SE engine lasted the longest at about 282, 000 miles. This was a daily driven, autocrossed car. I got rid of it only because it was like Spy Hunter when getting onto the freeway. 
I'm saving up for a rebuild. It will be done by Mike Henderson's (GT-3 SP regional champ) engine builder. According to him, even rotors will crack after around 40 to 60 hours of track time. That's racing for ya! My street car will never be driven that hard, even on track days. I'll be hoping to get a good 10+ years of life out of this engine.
I'm saving up for a rebuild. It will be done by Mike Henderson's (GT-3 SP regional champ) engine builder. According to him, even rotors will crack after around 40 to 60 hours of track time. That's racing for ya! My street car will never be driven that hard, even on track days. I'll be hoping to get a good 10+ years of life out of this engine.
Interesting thread.
I don't know if Paul Winter frequents this forum, but he has a track only 3rd gen that goes about 10k miles between rebuilds, which is about every 3 years.
This is a big single turbo (about 450 HP IIRC)
Formula Mazda's reportedly go 3 years between rebuilds as well. Anyone know differently?
I don't know if Paul Winter frequents this forum, but he has a track only 3rd gen that goes about 10k miles between rebuilds, which is about every 3 years.
This is a big single turbo (about 450 HP IIRC)
Formula Mazda's reportedly go 3 years between rebuilds as well. Anyone know differently?
Lives on the Forum
Joined: Sep 2003
Posts: 5,707
Likes: 6
From: BC, Canada
I was at an SCCA club race a while ago (1-2 years) and I spoke with a guy there who was running some Fromula Mazdas, and according to him someone had won the championship with a 7 year old motor. IIRC the guy was running a business servicing and preparing the FM cars for racing for clients with more $$ than time, so I'd think he knew what he was talking about, but those cars also run rev limiters with a maximum allowable engine speed of 6850rpm according to the rule book.
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