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-   -   Race Motor/porting Questions (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/race-motor-porting-questions-24863/)

pusher 09-16-2003 06:23 PM

I'm Aiming to build a 200rwhp N/A FC, I'm more concerned with road courses than I am the drag strip. I here about people doing large raceports and bridgeports, but all they do is 1/4 races. I was wondering how these would hold up in a longer road race. So a couple questions.



1)Is it possible to get 200whp out of a moderate streetport?(I'm sure the answer is yes) OR would it be easier to go with a small bridgeport?



2)What else is needed with a bridgeport? I've read that you can use stock seals/internals and it will work fine. Will I have to buy bigger injectors? Also I'm guessing the stock ecu will go crazy with the added fuel and air, so I was wondering if a piggyback or standalone was NEEDED(I know that a standalone would be best)



3)Finally, this would be my daily driver, luckily I dont have to travel far daily. What kind of gas mileage could I expect? I've heard its bad gas milage but is it l15mpg bad or 5mpg bad?



Thanks

thekid 09-17-2003 12:49 PM

I currently road race a steet ported N/A 13B 4 port that produces about 200 hp. I have also used a street ported 6 port 13B that had about the same power. I use a Weber 48IDA with 42mm venturies. When the Formula Mazda series started I got some information from the engine builder that the series engines made 195 hp on the dyno with the injection removed, Racing Beat 48 Dellorto kit, 6th port sleeve removed, headers, and 7000 rev limit. I keep the revs under 8500 and the motors last 2 - 3 seasons. Some of the Formula Mazda guys have gone over 5 seasons. Conclusion, you don't need a bridge port for 200 hp.



If you want to stay with injection check out Simple Digital Systems (www.sdsefi.com). They have a stand alone unit for the rotary, and in their technical pages a build-up on a plenum type manifold. See this website www.rx7.voodoobox.net for somebody who is doing what you want to.



I get 10 - 12 mpg on the race track, so street use will be much better.



Good luck.

Robbomaz 09-18-2003 09:43 PM


Originally Posted by thekid' date='Sep 18 2003, 01:49 AM
I currently road race a steet ported N/A 13B 4 port that produces about 200 hp. I have also used a street ported 6 port 13B that had about the same power. I use a Weber 48IDA with 42mm venturies. When the Formula Mazda series started I got some information from the engine builder that the series engines made 195 hp on the dyno with the injection removed, Racing Beat 48 Dellorto kit, 6th port sleeve removed, headers, and 7000 rev limit. I keep the revs under 8500 and the motors last 2 - 3 seasons. Some of the Formula Mazda guys have gone over 5 seasons. Conclusion, you don't need a bridge port for 200 hp.



If you want to stay with injection check out Simple Digital Systems (www.sdsefi.com). They have a stand alone unit for the rotary, and in their technical pages a build-up on a plenum type manifold. See this website www.rx7.voodoobox.net for somebody who is doing what you want to.



I get 10 - 12 mpg on the race track, so street use will be much better.



Good luck.

Well that saves me a bit of typing https://www.nopistons.com/forums/pub...#>/biggrin.png

I have seen just over 200hp with a street port and a 48IDA. The Weber can be made to be extremely tractable. We have issues finding the proper emulsion tubes for them.

For sure injection is better but the factory computer will probably not do the job. An increase in fuel rail pressure MIGHT help but realy a standalone is the way.

A PP I built made 295hp on a Weber, had to idle at 1500+ (BRAP BRAP BRAP!)& awful fuel consumption (10-11mpg to & from the track)

Adding injector stacks to the IDA manifold and a Microtech gave 330hp, 900 idle & 16 mpg during transit stages. The stacks used the same trumpets as the IDA so sounded like the Weber too!



And as thekid says, keep the RPM sensible & the std bits last just fine!

pengaru 09-19-2003 01:38 PM

I was just @ grattan earlier this week with a group running formula mazda open wheel cars with the 6 port 13B sealed motors. The mechanic there said they had 180HP at the flywheel and put down around 160 at the wheels.



They are running 50mm weber carbs modified by star mazda, timing was fixed @ 22BTDC.



It will take some porting to get 200HP at the wheels most likely, a street port should do. These cars have an efficient drivetrain so you will need more power at the flywheel for 200HP at the wheels than the formula mazda cars do, which are mid rear and use a volkswagen transaxle.



The cars were all within spec for competing in the formula mazda races so they were not getting all power possible.


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