Ben 84 RX-7

I currently own and race an '84 12a race car in ST-2 with EMRA. ST-2 is the same class as ITA in SCCA. I have only driven this car in 4 events. 3 sprint races and 1 enduro. I got the car as it is and have only changed the rear suspension with a panhard bar and lower links. Everything else came already prepped. The car is killer...in the corners. I am getting smoked on the straights. By everything. I want to make my car as fast as possible...while staying in the rules. I really don't want to win if I do it in an illegal car. This is my first rotary engine and I am still learning a lot as I go. Here is the list of mods as far as I can tell.

- Air pump removed, no PS, or AC.
- Took off the fan, only belt used is alternator belt.
- Header that goes right into one pre-silencer, then splits at the rear into two mufflers.
- MSD ignition.
-K&N air filter.

I think that's about it. What else can I do and still be legal? There are other guys in the same car KILLING me in a drag race. I know there is more horsepower here...just trying to find it!

If anyone has some ideas or knows about ITA rules, please feel free to contact me by private message or email. All help is greatly appreciated!

THANKS!!!!

rhinor61

You are choking your motor off, why a pre-silencer and 2 mufflers. I ran straight pipe, under the rear axle into a DynoMax Ultra Flo.

Have a new carburetor built to meet your rules, bigger jets means more fuel with the right intenernal work. Paul Yaw did all my work but his focus is the Rx-8, so I would say Carl (PBand J racing) can do a good job since he is a racer himself.

I would have a small electric fan installed, maybe a 626 pusher unit wire on a switch won't help on power but will save a motor from over heating. I would go with the a GSL-SE oil cooler (or 79-82 unit) to help keep the oil temperatures down.

Take any items off the car that are not require by your race class. Extra weigh means slower lap times.

Brakes!! Got to do everything possible to give you the best braking, cause the later you can brake the fast the laps times.

LSD, have you tested this to see if you need to have the clutch discs replaced?

John

Ben 84 RX-7

Thanks for the info John!

I do have an oil cooler. The car does have some more mods than I listed as I was concentrating on the engine as the weak point right now. The brakes are stock calipers and rotors as the rules say. I have racing pads and braided lines. High temp fluid and they lasted the whole 1 hour enduro with no fade at all. The exhaust is what was on the car when I bought it. I have heard that unlike piston engine cars...it is good to keep the exhaust from the two rotors seperate the entire way. Is this true? What is the reason if so?

I don't mean to sound like I am complaining about my car...I love it and am putting up some pretty respectable times at the tracks I run. I did a 02:28.42 at Watkins Glen and a 1:06.78 at Lime Rock. I would make up tons of time on people on the brakes and through the corners...once we hit the straight...they crushed me. I think my exhaust is a big anchor.

Thanks again for your help...also, do you know a ballpark figure for having my carb done for ITA rules?

cpa7man

iTrader: (2)

I'm a newbie at SCCA suff, but I don't think you can have an MSD ignition in ITA. I'm in the process of ordering the rule book.

The car I'm looking at buying has the same exhaust set up as Rhino. I'm not sure about the carb. I know the guys that are competitive must have the engine tweeked somehow???

Have you applied for your SCCA novice permit yet?

Ben 84 RX-7

I'm not going to run any SCCA events as of now. I am sticking with EMRA. They have never said anything about the MSD...so I'm not going to ask! cpa7man - do you have presilencers at all? Or just headers into pipes into mufflers?

Re-Speed.com

iTrader: (3)

Ben 84 RX-7, my car had a header and 2 pipes that connected together about 3 feet from the end of the header. Then single pipe over the rear axle to a Borla. On the end of the Borla I had a 90 degree turn down that was pointed away from sound control at each track.



-billy

cpa7man

iTrader: (2)

No it just has a header that dumps into a pipe, than the cat back is just a pipe with a big tin can looking muffler. Its very loud. I'm not sure what type it is. It runs under the rear end. When I get it up on a lift I'll take a picture of it.

Rx7carl

John's right, your choking off alot of mid and top end with your exhaust. How close is the EMRA rules to ITA? Im going with current IT rules here. Obtain a 79-80 intake (best of all the 1st gens). Have the carb done, or at least re-jet for power (83-85's are easiest to work with). Upgrade to a good fuel pump (I prefer the Carter), and a good regulator (Holley 1-4psi). Dont use the dial type cheapo, they limit fuel flow too much. Get a good air filter assembly, ISC, Mazdacomp and RB all sell good units. Upgrade to an MSD6A for at least the leading (it makes a difference, trust me). And IT rules state ANY ignition is legal as long as the dizzy is used for spark timing abd distribution. Get a good set of spiral wound wires ( I use Moroso Blue Max). You can get them in premade sets. If your interested in a carb, PM me.

On another related note. The trans ratios on these cars stink. A 4.88:1 rear gear kicks butt. I love mine. Not more power or torque, but it does give you MUCH more APPARENT power and torque. My car accelerates like a bat outta hell, but tops out at 140@8500.

Ben 84 RX-7

Carl - thanks for the help! I will get under my car today and check out each of those things you listed. EMRA's rules for ST-2 are similar to ITA...with much looser enforcement - but I really don't want to start cheating to win, you know? I am interested in a carb...but have no idea what kind of money is involved in getting one done. As far as my gears go...I realize they are not cutting it. Not sure where you race, but I run at Watkins Glen and Lime Rock mainly...and have never touched 5th gear at either track!! Shifting at 7,500 rpm's. What do you suggest for exhaust? Two pipes the whole way or collect somewhere?

Thanks again!

DriveFast7

iTrader: (1)

with a stock ported motor you'll get more peak horsepower and a wider powerband if you run two pipes back as far as you can and collect right before the muffler. Use a nice aftermarket collector. Magnaflow makes one with a big chamber and is short. Flowmaster makes a good collector too and I've used one on my 1st gen.

Run a header with two straight pipes collect just after rear axel into a Borla, Magnaflow, etc. 3" pipe muffler. Put a bolt on mandrel bent 90 degree exhaust tip on there that you can rotate away from the sound meter at each track.

TrentO

Ensure you run the exhaust pipes straight for as long as possible. On my car I have two tubes which run from the header under the rear axle to about 6" behind the axle. After the axle they Y into a 3" Magnaflow. I'd say I'm up about 5 hp from the old setup which Y-d in and then went over the axle and into a muffler. I'd also recommend getting cold air to the engine with some kind of cold air intake and building brake ducts for the extra longevity in the brakes.

Sign up with Mazdaspeed and order those 4.88 gears as soon as you can, the difference in acceleration is worth it. You will want to ensure your driveshaft is in balance before you put the gears in though, as you will be spinning it very high with 4.88's in the car. Might be worth doing the needle bearing / hardened yoke they sell to control the transmission yoke vibration. The other route (which I use) is to buy a new junkyard transmission and driveshaft every season and ensure the driveshaft fits up properly.

-Trent

cpa7man

iTrader: (2)

Does what you are discussing above apply to ITA, Spec7 or both? Is IT7 in your sig the same as Spec7? Sorry for the newb questions.
I just purchased a car and getting ready to go to scca school. The car is ready to run, but I would like to make it go faster. It runs a stock air cleaner and I was told thats what you had to run. As far as what else is on the car I've got to check it all out. When I ran the car I did notice the gearing needed help.

Ben 84 RX-7

I have been told that it is best to keep the exhaust two seperate pipes the entire way so the airflow never mixes. Is this true? If so, why?

DriveFast7

iTrader: (1)

Nope. We want exhaust scavenging. That's when you merge the two pipes together and the exhaust pulse from one rotor sucks the pulse from the other down the pipe.

rhinor61

Brad is correct, bring them together at the rear axle, unless you want more power in the corner and less to end you bring them together and muffler dumps out behind the drivers seat.

Even a pistion V-8 requires a 'H' pipe to join the exhuast, balanced the engine exhaust pressure.

John

Speed Raycer

Not to sound flippant, but work on your corners before the straights. "Out handling" them in the corners could mean that they're using a slow in, fast out approach. They'll walk you like you were standing still on the straight if your actually loosing momentum or scrubbing off speed in the corner.

Case in point... a very good EP driver rented a IT RX7 that I helped build a couple of weekends ago. The car has a stock 3.90, stock ignition w/Blaster coils, stock carb (rebuilt), stocker type fuel pump, Holley FPR, legal "cold air" intake, RB header into 3" pipe. Nothing special at all. My new car has 4.88's, SDJ carb and intake, Carter pump, Holley FPR, Dual Direct fire MSD's 4 puck clutch etc. etc. I would actually pull on him through some of the turns but on the last turn before the long NASCAR turns and straight, he took a completely different line than I did. I gained SOME space in the first 30 yrds or so, but he had so much more momentum than I did that he had about 10-15 car lengths on me at the end of the straight.

So... before you toss too much money at mechanicals, take a good look at your driving. Obviously, everything mentioned previously (gears, carb, exhaust etc) will help the top end, but picking apart your line, or having someone else do it, will do wonders!

Ben 84 RX-7

Speed Raycer - you bring up a very good point, and I totally agree with you. The main reason I know my car isn't setup as well as it could be, is from my most recent 1 hour enduro at Lime Rock. I wasn't in the points race for the enduro series, so I was using the hour of track time for practice more than anything. I had the opportunity to try many different lines around the track and many different driving styles. You are definitely right...my fastest lap times were when I used a smooth in, fast out approach to corners. The banzai late braking laps felt fun...but were definitely not quick. I was able to notice a substantial difference in engine rpm's by the time I hit the next corner proving I was able to carry more speed. But (always a but!), no matter what my line...I was STILL getting passed on the straights. Some of these guys are just plain better drivers than me, I realize...but I also know a couple that aren't. I also do know that they have RX-7's like mine...but are much more sorted out than my car is. Next year however..!

Rx7carl

Man this is my favorite part of the forum. Good, logical ideas, backed by info and real experience. No bs.

Never been to the Glen or LRP, but seen races there. Im down in the south. The longest straight I run is at Roebling Road in Savannah. 4.44's would probably be better as I top out in 5th at 8500 (137mph) about 2/3 down the straight. As one of my influences (Carroll Smith) has said, its a horses for courses thing. At a tight twisty autox or Waterford Hills kinda place 4:88 or even 5:12 might be more appropriate. When I run at Daytona next year I plan to carry a 3:90 just in case Im spending too much time watching cars fly by me on the Oval.

Im in a quandry over the exhaust. Ive tried every setup and still seem to be drawn back to long primaries. It seems the new flavor is shorties. I have this on the car now (from ISC). Seems Ive lost my top end , but pulls really good thru the midrange. I may go back to long style and see what my lap times tell me.

Rx7carl

AFAIK, none of that stuff is SPEC7 legal. IT7 is a class for ITA prepped 1st gens. It's given new life to a car thats been outclassed and made obsolete in ITA. SE-DIV, and now CEN-DIV recognize the class. WHRRI also usues this class but they call it ITR I think. Is that right Speed?

So what class are you running cps7man? And work on the driving first. I'm a mediocre driver with a good car. But I'm learning, and taking pointers from anyone willing to critique me. Listen to your instructor at school about your driving, and really work at it.

Rx7carl

Doing this is also much louder. You stand a good chance of getting busted by sound control. Take the tip, collect, and use an elbow to point away from sound control.

rhinor61

Funny everybody says to point the exhaust tip away from sound control, at Laguna Seca they have monitoring microphones on both sides of the track as you climb the hill between turn 5-6.

I agree with Carl, short exhaust collect at the muffler in the middle of car is going to take away from your top end power, on long straights you going to hate it.

John

Rx7carl

Damn California! Got you by the ***** huh?

cpa7man

iTrader: (2)

I'm going to do the scca schools. The plan right now is to just get my regional competition license. The car is set up for ITA, so I'll go the path of least resistance. I don't think we have IT7 in the Texas region?? I know Spec7 is big. I'm not interested in being competitive right now, just want to get my feet wet. I've got an 85 rolling chasis with disks/LSD and no sunroof ready to prep as well as the fugly ITA car thats ready to run (but is very rough) https://www.rx7club.com/attachment.p...postid=2312875

Carl I'm like you not a great driver but willing to learn.

The rolling chasis came with lots of stuff like Tokico blues, RB header, 2 radiators, extra motor and such. So I'll set it up to run whereever I feel I can be most competitive in for the 2005 season.

Rx7carl

Cool, yea Spec7 is big out there from what I hear. Just run ITA and get your seat time. And dont forget............HAVE FUN!

Barwick

Greaaaaaaat.... the car I'm buying has a 5.12 rear end. Luckily for me the track I run at you don't top out at anything more than about 110 unless you've got a really high powered car