Anyone here have any friends convert an RX7 to a Renesis for racing?
 

This is a class in SCCA down in the south East. http://www.ncrscca.com/it-7r-rules


IT-7R Rules

for 2012
1. Definition, Purpose, Philosophy and Intent:
The purpose of this regional class is to allow a place for the IT-A and IT-7 RX-7s to run due to the unavailability of 12A engine parts while maintaining the IT philosophy and budget. Any allowable modifications, changes or additions are as stated herein and there are no exceptions. IF IN DOUBT, DON'T. IT-7R will be grouped with IT for Southeast Division events.
2. Specifications:
Shall conform to GCR 9.1.3.C *Additionally any 2004-2008 Mazda Renesis engine may be used and fitted with Racing Beat steel flywheel part # 11436 or 11437 (same flywheel. Different clutch hardware)
3. Authorized modifications:
Shall conform to GCR 9.1.3.2 a-d
4. Engine Compartment:
a) Engine management computer shall be replaced with a MegaSquirt 3 ecu.
b) Throttle body shall be replaced with BBK part #1700
c) Throttle body adapter shall be part # RE-1500-005 (manufacture to be determined)
d) Stock ignition and coils shall be used
e) Stock RX-8 exhaust manifold shall be retained. Exhaust shall be maximum of 3 inch I.D. single tube or dual 2 inch I.D. tubing.
f) The addition of an external scatter shield per GCR 9.3.39 is mandatory
g) Battery tray may be removed and battery of minimum 243 cubic inches (length x width x height) may be used and mounted on the structural rail (frame rail) lengthwise, no more than 5 1/2 inches from the radiator support.
h) Engine mount shall be part # RE -1500-001 (manufacture to be determined)
i) Intake shall be unmodified spectre Part # 8791 , vibrant part # 2175 and k&n part # rr-3001
5. Engine Cooling System:
Shall conform to GCR 9.1.3.3 a-g
6. Transmission/Final Drive:
Shall conform to GCR 9.1.3.4 a-f *Additionally any 1979-1991 RX-7 non turbo transmission may be used.
7. Chassis:
Shall conform to GCR 9.1.3.5
8. Suspension Control:
Shall conform to GCR 9.1.3. c
9. Suspension Mounting Points:
Shall conform to GCR 9.1.3.d
10. Brakes:
Shall conform to GCR 9.1.3.6 *Additionally any 1979-1991 RX-7 brake hubs, calipers, rotors and mounts or aftermarket equivalent may be used provided they mount to the stock 1979-1985 spindles.
11. Wheels/Tires:
a) Maximum rim diameter is fifteen (15) inches. Maximum rim width is seven (7) inches. Minimum weight of wheel shall be 13 lbs without spacers.
b) All cars shall use the Toyo Proxis RA-1 or R888
12. Body Structure:
Shall conform to GCR 9.1.3.8
13. Driver/Passenger Compartment-Trunk:
Shall conform to GCR 9.1.3.9
14. Safety:
Shall conform to GCR 9.1.3.10
15. Measurement Standards as specified:

IT-7R Mazda RX-7 1979-1985
Engine Type w/13B Renesis2
DisplacementRotor2600cc
Comp Ratio 10.0
Wheel Base (inch)95.3
Wheel Dia. 13/14/15
Gear Ratio Stock 79-91

Brakes Std(mm)
(F) 227 Disc(R) 236 Disc Weight of car would be 2330
alt.(F) 277 Disc(R) 272 Disc Weight of car would be 2380


Be sure to thank our supporters and ask for your discount on parts for your IT-7R car.
Racing Beat
PF Tuning
Mazda Motorsports Development

if they are going to specify an MS3 then they should also specify a 4 port engine

I thought they used the 6 port but not really sure. I am not involved in the class but found it to be an interesting swap...

Stephen

I didn't think that the MS3 can control the APV valve or handle 3 pairs of staged injectors, but I could be wrong

Just use an S2 manifold and injectors... i'm not sure about the MS3 but there should be some plugins to enable apv operation (or any other 0-5v \ 0-12v electrical gizmo one may have).

Could you guys tell them that they're dumb in classifying the engine as a 2.6l? The FIA uses a different number... smaller ;)

Except this is a racing class with a very specific ruleset. I don't see allowances listed in the rules above that allow you to do any of that ...

So the rulebook just came out of their arse like most of the times?

That's nice to know, especially since the ms3 is a piece of junk.

time to run the stock ECU and put it in the MS case?

i almost built a car like this in 2006-2007, it ended up with a P port 12A instead, the P port was cheaper (at the time), although power output is pretty much the same.

car is simple fun.

I think part of the goal of the class was to keep the speeds similar to the others running the 12A, although that is not mentioned in the "Definition, Purpose, Philosophy and Intent" I may be way off in that thought but seeing posts on other forums when they were creating this class I got that opinion. I did not participate in the creation of the class, here in the North East plenty of 12A cars and parts seem to be available.

Stephen

The exhaust on the 12A and 13B, used in first gen RX7's, were peripheral port. Did you make the intake peripheral too?
The 12A was in ITS first came out. I ran one before they reclassified it into ITA.

peripheral intake too! its so much better than side port it is funny.

its unfloodable, has the torque curve of a truck, is idles @900rpm, gets excellent mileage (i did 2 events on 1 tank of gas, my buddy with an NA FC used 3.5-4), it melts mild steel, and wakes up vampires!*

the only place where its not vastly superior to side ports is part throttle low rpm, and i'm sure the unburned hydrocarbon emissions are high...



*i ran it up and down the street before sevenstock a couple years ago, and the neighbor came over and told me it was so loud it could wake the dead. since it was 2pm, i'm thinking that the only dead people that sleep in the day time are vampires... her follow up was to ask if it had a muffler, and she wasn't happy when i said it had 3.....

then of course at sevenstock everyone was telling me how quiet it was.

I think this is overly complicated. If they want to keep IT7's on the track they should just allow 13b (not renesis) swaps. Cheap and simple.

It is unlikely that they were intending this car to be competitive with the existing IT7 cars since they will run more like EP cars even at 2380. I think IT7 is 2180. Also the brakes are going to need a lot of attention, in my IT7 racing days the brakes were a weak point even with the 12a (mine had 105rwhp).

IT7 is great fun, the cars can be made to work very well and it is nice to see someone making an effort.

Apparently some of you aren't accustomed to how competition rulesets work.

It very specifically states that an MS3 ECU must be used

My general inclination reading it through the first time was that its not very well thought out

Keep in mind this is one guys brain child, not a product of the Club. He has been trying to sell this concept for a year or more, and I don't think he has had any bites. When he pitched it at the town hall during the Runoffs last year the response was, "there is already a class for an FB with a motor-swap, its called STL/U." We need another class for old stuff why?