Here's my situation:



- I race a C Sports Racer (1300 lbs.) in SCCA Nationals in the Northeast. If you are not familiar, they are seriously fast cars.



- My current motor is putting down 190 rwhp using a Hewland gearbox. I am hoping to do a lot better than that.



- I am familiar with porting and have an excellent race prep type machine shop as one of my sponsors.



- I don't mind buying the parts I need to build the proper motor.



- I have two motors, both are '85 13B 6 port as used in Formula Mazda. One motor has been street ported and the other still has Darryl Drummond's Formula Mazda seals on it.



Here's my problem:



- Not being familiar with the different configurations of this motor, I don't know what parts should be replaced for maximum power.



- I don't know what the best port timing should be for my application. I have the excellent Ito templates to give me the shape of the intakes.



Here are the restrictions:



- I don't want to change from using my current front motor mount.



- The rules allow only street porting of 13B's.



- I am using a Star Formula Mazda intake and exhaust as well as the Weber sidedraft (48 DCOE, I think).



- Motor must remain normally aspirated.



- I am using two MSD 6AL's.



- I would like to be able to race about 1500 to 2000 miles between freshenings.



I would be appreciative of any advice you might have about port timing, motor parts and also clutches and flywheels.



Thanks.

 

I would contact Carlos at CLR in Miami. Beveled Rotors and a balanced rotating assembly will help your cause

 

I thought I could whip out the SCCA Rule book and fill you in, but you need a lawyer with an automotive background. The only reference to the rotary under Formula C I can find is on page FCS-27 and no data is provided. Page FCS-26 has a reference for X formula "C" cars says look under Formula Atlantic 17.1.6.A.



And in that section on page FCS-7 there are two rotary options. Both are 12As. A bridgeported 12A with a 36 MM venturi. With injection you could get 260 HP (tops) from that setup. Or the street ported 12A with no restriction at all, and you might get 230HP from that with a wider power band.



There is no mention of a 6 port. Or a 13B at all.



There was a set of pictures published to establish what a street port should look like. It did not restrict timig but limited short side to a point that the junction of the side seal and corner seal must not be exposed to the intake port. But that leaves a bunch of room to work.



But the only 13B is the Renesis in Spec Pro Mazda.



So call legal at SCCA. Find out what engine is allowed in Formula "C". And then we will port the crap out of it,

(to the letter of the SCCA law).



Lynn E. Hanover

 

Lynn, I'm not trying to be a smart-*** and I would really like your input. I have been racing these cars with the SCCA for 11 years and about 150 races. I know the rules. If you doubt me and want to wade through the GCR, that's up to you, but I have given all the info I think necessary. I 'think' my car is covered on page SRCS-10 or close to it.



As I said, I race a C Sports Racer, not a Formula 'C'ontinental, not a Formula 'A'tlantic, and not a Spec Pro Mazda. I know pretty much what is required, legally, to win and that is what I am seeking.



Thanks,

Don MacCluskie

 

I'm sorry Don.



I made a mistake. After 35 years of SCCA racing, with the last 10 runoffs invitations in rotary powered cars, I lost my mind.



I looked up the "Street Port Rule" and pictures for both 6 port and 4 port, street ports, and that gives you some help right away. Those pictures were supplied to SCCA by Dave Lemon of Mazda Trix. A reasonably successful (GREAT) engine builder. They seem to be all worried about the open line being moved so far as to expose the junction of the leading end of the side seal and corner seal to the intake port.



I know you hate to read the rule book, but since the SCCA cannot write a rule about anything that makes sense or does what they think it will do. You may have noticed that the intake manifold rule with one butterfly per housing and no plenum outlaws every rotary. Because you need the plenum to feed both runners for each housing. So in comp board meetings at the runoffs they admit that it has to have one to work, but still no rule that allows it for rotaries. It has to have a plenum, and a plenum could be the little room below, or beside the carb where the runners join, or.......................................????????? ??????



But I digress.





So it seems obvious that the open line would be moved to that location that is just legal, as the first part of the porting program. In an artical he wrote, Lemon said he had trouble getting used to shifting his E car at 10,000 RPM.

So, I'm thinking that he could be using the 6 port irons at least on the ends. I think the 12A center irons have better looking runners and ports. Since Beasley could win any time he showed up, I would call him and see what he was using. He is not much on engines but he may know that. Daryl builds his engines, and certainly knows what combination is in use, but may be cryptic on the most important parts. I have not seen a 6 port in use for GT-3, and suspect that it would be a poor choice, when a bridgeported 12A is legal even with 34MM chokes. Probably 245 HP. Vice 230 from the street ported 6 port. Just under 8 HP more if injected. But add 25 pounds to minimum weight. So if the car is overweight anyway, I would inject it.



I notice that only the 12A is listed on the Mazda Trix web page for CSR.



I have two Drummond GT-3 12As, and have been very happy with his service.



The list of stuff I don't know yet is still pretty long. I would like to try early turbo ends and 12A center iron, with an epoxy intake manifold with adjustable plenum and runner lenghts. We need about 265HP to be competitive, (in GT-3) with about 250 in hand.





Lynn E. Hanover

 

"Engines may not have a plenum common to multiple cylinders or rotors". This simple sentence would express the intent of the rules very cleanly and concisely. Therefore, it wouldn't ever make the rule book.





The E/Production engine? I remember hearing about playing with 6 port end housings, with the divider ground out to make one enormous port.

 

i remember that too, but i went back and looked (i wanted to know what engine they ran in e prod) and it doesnt specifially say

 

I think Lemon would give that up just for asking. Drummond and Stan Lizauskas were both building E engines and when questioned, claimed within one HP of each other. Stan liked a bit less revs than Daryl.



That was 228-229 HP. Not nough to get the job done in CSR I am thinking, and no longer enough for E production. Daryl is still building engines for various classes and all of the Pro Mazda stuff. Stan closed his

shop, but might build you one if you can find him.



The less obvious requirement is for minimum rotational weight. The 5 1/4" or smaller 4 1/2" Tilton style clutch. The Mazda comp spider ring gear and flywheel, or a cut down Tilton Chevy wheel and an old RX-2/3 flexplate. Minimal preload on the transaxle side plates, and pinion preload. The cat **** thin diff/trans lubricant.



The road wheels must be light overall with that minimal weight in the centers with spun aluminum rims.

I would try the bleed valves for the wheels so you are at ideal tire pressures all around from the green, and not waiting a lap for the tires to come up to race pressures. I would check examples of available tires of similar performance for the tire weight. Run the light one. You can give up a little sticky for a light tire and get it all back down the first long straight. Not only do heavy tires look like heavy flywheels to the engine, they look like a heavy car to the brakes.



Rebuild calipers often, and instantly when you feel one draging with just hand pressure on the wheel. The "O" rings stiffen up, and piston retraction slows a bit.



Read all of Carroll Smiths books. Read "Driving in competition" by Johnson. From the stone age of racing, but shows how to evaluate corners into the three classes. Going to be good in 2006 when everyone shows up at Kansas and has never run that track.



And about one thousand other things I cannot think of at the moment.



Lynn E. Hanover

 

Thanks a lot, guys. So far, you have given me some serious things to consider.



Banzaitoyota said, "I would contact Carlos at CLR in Miami. Beveled Rotors and a balanced rotating assembly will help your cause."

====> Thanks, banzaitoyota. I don't know what beveled rotors are, but, I will try to find out and definitely have everything balanced.



---------------------------------------------------------------------------------------

Lynn said,



"I looked up the "Street Port Rule" and pictures for both 6 port and 4 port, street ports, and that gives you some help right away. Those pictures were supplied to SCCA by Dave Lemon of Mazda Trix. A reasonably successful (GREAT) engine builder. They seem to be all worried about the open line being moved so far as to expose the junction of the leading end of the side seal and corner seal to the intake port."

=====> I have tried to find the "Street Port Rule" in the GCR and could not. Could you point me in the right direction, please? I thought street porting meant pretty much anything goes except adding more holes for the intake.



"So it seems obvious that the open line would be moved to that location that is just legal, as the first part of the porting program. In an artical he wrote, Lemon said he had trouble getting used to shifting his E car at 10,000 RPM."

=====> Where may I find such articles, Lynn?



"So, I'm thinking that he could be using the 6 port irons at least on the ends. I think the 12A center irons have better looking runners and ports."

======> OK, so I need a 12A center iron. Are they all the same, or, is there a preferred one to use?



"I notice that only the 12A is listed on the Mazda Trix web page for CSR."

=====> The reasons I am trying to avoid the 12A are because I am not sure if they have the proper front motor mounts and I think the narrower rotor housings might make my present intake and exhaust unusable.



"I have two Drummond GT-3 12As, and have been very happy with his service."

=====> I have not heard a bad word about Daryl Drummond from anyone.



"We need about 265HP to be competitive, (in GT-3) with about 250 in hand."

=====> I, too, need 265HP. I now have 190 at the rear wheels : ^(



"The less obvious requirement is for minimum rotational weight. The 5 1/4" or smaller 4 1/2" Tilton style clutch. The Mazda comp spider ring gear and flywheel, or a cut down Tilton Chevy wheel and an old RX-2/3 flexplate. Minimal preload on the transaxle side plates, and pinion preload. The cat **** thin diff/trans lubricant."

=====> I'm very interested in getting the best clutch and related parts. I use the clutch only to get the car moving in first gear. I have never used anything other that standard street clutch and flywheels, so, I have no background here but think the proper choices are critical. I'm not so sure of using the cat **** thin oil, though.



"I would try the bleed valves for the wheels so you are at ideal tire pressures all around from the green, and not waiting a lap for the tires to come up to race pressures."

=====> I have never heard a positive reference to these valves before. Have you used them yourself? Hoosier tells me to not run my tires under 18psi. I go on the track usually with about 14psi and must heat the tires quickly. In the interest of not having a tire fail, I error on the side of slightly higher pressures than optimal. After a national race I usually find that I am carrying about two psi more than optimal. I should probably try those things and see for myself.



"You can give up a little sticky for a light tire and get it all back down the first long straight."

=====> Not in CSR. We pull well over 2 g's in corners and easily over 150 mph on straights such as Watkins Glen and Summit Point. To give up a tad of stick in the corners is to add serious time to lap times that cannot be made up on the straights, imo.



"Not only do heavy tires look like heavy flywheels to the engine, they look like a heavy car to the brakes."

=====> Agreed.



"Read all of Carroll Smiths books. Read "Driving in competition" by Johnson."

=====> All of the Smith books travel to each race.



"And about one thousand other things I cannot think of at the moment."

=====> A thousand other things, huh? Please, continue.

 

https://www.mazdatrix.com/sccaportrule.htm



I'm not much up on my circuit racing, but apparently the old definition of a street port was "the port window must be only one hole" or "the circumference of the port must be contiguous". There was a great thread on here referring to some of these porting types, such as the comb port, or making a bridge port most of the way and supporting the tab with a post or two, to try to get the advantages of a bridge port while meeting the letter of the rules. Unfortunately, I believe this post was lost when the forum was hacked a ways back. Of course, the rules have now been changed to something with no loophole.



{quote]"So it seems obvious that the open line would be moved to that location that is just legal, as the first part of the porting program. In an artical he wrote, Lemon said he had trouble getting used to shifting his E car at 10,000 RPM."

[/quote]



http://www.rx7club.com/showthread.ph...01#post1586101 might be the "article" in question.