How to get more than 200hp on a NA?
found this its from awile back
what gas should i use??? rx7club
Originally Posted by 13B4port
octane does 2 things. makes burns last longer and also requires a lot higher compression to cause detnation. for those of you who don't know waht that is, it's when you compress a liquid(in this case gas) untill it's super heats itself and causes it to ignite. desil engines run on this property, they run a compression around 20:1. so people who run turbos and high compression engines run a hgiher octane and also retard their timing to keep it from detonating. why is detonating bad on a gasoline engine? very simply put that the rotor/piston doesn't get threw compessing the gas and when it exploids, it cause the rotor/piston to move backwards. needless to say it's bad.
on the other side. if you have a normal compression engine like a stock 12a or 13b, and run high octane, 2 things happen. a and b put together) the burn doesn't completely happen in the camber, this means that there is less energy being created to push the rotor b/c the gas is still being burnt in the exhasut pipe. so you run a lower octane that will all be burnt in the chamber meaning that the full amount of energy is being used to push the rotor. if you run that higher octane, you will stillhave the same amount of gas tring to burn but it won't burn fast enough. so you end up loosing power. but the diffadvantage of having all the burning in the chamber is that carbon will build up(happens in piston and rotory engines). to fix this, about once every 2 months run a 1/2 tank of higher octane(the premium stuff). the burn will last jsut long enough to get to the exhasut manifold, that way all the carbon is pushed out of the engine. it's the same as going and buying STP or any other fuel treatment. al they do is raise the octane level.
hope this answeres some questions
on the other side. if you have a normal compression engine like a stock 12a or 13b, and run high octane, 2 things happen. a and b put together) the burn doesn't completely happen in the camber, this means that there is less energy being created to push the rotor b/c the gas is still being burnt in the exhasut pipe. so you run a lower octane that will all be burnt in the chamber meaning that the full amount of energy is being used to push the rotor. if you run that higher octane, you will stillhave the same amount of gas tring to burn but it won't burn fast enough. so you end up loosing power. but the diffadvantage of having all the burning in the chamber is that carbon will build up(happens in piston and rotory engines). to fix this, about once every 2 months run a 1/2 tank of higher octane(the premium stuff). the burn will last jsut long enough to get to the exhasut manifold, that way all the carbon is pushed out of the engine. it's the same as going and buying STP or any other fuel treatment. al they do is raise the octane level.
hope this answeres some questions
love the braaaap
Joined: Jul 2003
Posts: 3,771
Likes: 5
From: Bognor, Ontario
Your doing real good if you made that 194hp at the wheels, thats about 240 at the flywheel. Besides freeing up the exhaust, there probably isn't much left you can do. You could go to dual 2 1/4" pipes and a straight through muffler. Might bring it over 200hp at the wheels, which is real good for a NA rotary. Only engine to do much more than that would be a J bridge or a P-Port. Also, as stated before run the lowest octane you can get. Mazda used super low octane gas in their race cars in the 80's, somewhere in the region of 82-84 I think. 87 will do fine for you though.
Originally Posted by 85rotarypower
Your doing real good if you made that 194hp at the wheels, thats about 240 at the flywheel. Besides freeing up the exhaust, there probably isn't much left you can do. You could go to dual 2 1/4" pipes and a straight through muffler. Might bring it over 200hp at the wheels, which is real good for a NA rotary. Only engine to do much more than that would be a J bridge or a P-Port. Also, as stated before run the lowest octane you can get. Mazda used super low octane gas in their race cars in the 80's, somewhere in the region of 82-84 I think. 87 will do fine for you though.
Joined: Jul 2002
Posts: 7,301
Likes: 3
From: District of Columbia
WOW those are really low numbers for that setup. there was a guy on here that made over 200whp with a racingbeat street port. A 13b Bridge port should be making at least 250 to the wheels. First thing you should do is check you compression. Something is really wrong here.
13b P-port on a budget
Joined: Nov 2004
Posts: 3,003
Likes: 0
From: Louisville KY
Man low # but sweet ride. I to have heard of a judge ito street ported motor putting out 210hp on a Dyno. A bridge should be some where near the 250 range or higher I would think.
Originally Posted by nick812
Man low # but sweet ride. I to have heard of a judge ito street ported motor putting out 210hp on a Dyno. A bridge should be some where near the 250 range or higher I would think.
Thread Starter
Full Member
Joined: Jul 2003
Posts: 123
Likes: 1
From: Qld, Australia
I'll post up the AFR data as soon as I can, I don't have it with me at the moment.
The 194hp was at the wheels it's not flywheel hp.
Still getting mixed comments about the hp #, some people think it's good, others think it's too low.
It's definately a bridgeport, the workshop that tuned it also built the engine and it has bridgeport stamped on the rotor housings, which is the standard procedure by the shop that built it. www.mazfix.com.au
I'm going to try a lower octane fuel and a few other things and see how it goes.
The 194hp was at the wheels it's not flywheel hp.
Still getting mixed comments about the hp #, some people think it's good, others think it's too low.
It's definately a bridgeport, the workshop that tuned it also built the engine and it has bridgeport stamped on the rotor housings, which is the standard procedure by the shop that built it. www.mazfix.com.au
I'm going to try a lower octane fuel and a few other things and see how it goes.
Hunting Skylines
Joined: Apr 2001
Posts: 3,431
Likes: 4
From: Brisbane, Queensland, Australia.
Dyno Dynamics dynos read approximately 15% lower then the Dynojet dynos which are commonly used in the US.
Combine that with the restrictive exhaust and your numbers are pretty much spot on.
I'd also recommend sticking to whatever fuel you did the dyno on.
Combine that with the restrictive exhaust and your numbers are pretty much spot on.
I'd also recommend sticking to whatever fuel you did the dyno on.
Originally Posted by Hyper4mance2k
WOW those are really low numbers for that setup. there was a guy on here that made over 200whp with a racingbeat street port. A 13b Bridge port should be making at least 250 to the wheels. First thing you should do is check you compression. Something is really wrong here.
i agree. i think those numbers are way low for a bridge. check out the numbers on FD racers SP 13b:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/finally-posting-my-%2A13b-dyno-numbers%2A-480924/
Hunting Skylines
Joined: Apr 2001
Posts: 3,431
Likes: 4
From: Brisbane, Queensland, Australia.
Originally Posted by aws140
i agree. i think those numbers are way low for a bridge. check out the numbers on FD racers SP 13b:
https://www.rx7club.com/showthread.php?t=480924
https://www.rx7club.com/showthread.php?t=480924
Dyno Dynamics figures usually add up to about a 30% drivetrain loss. So FD Racers car would only be making 160rwhp on a Dyno Dynamics.
Rx7's number are not low. End of story.
Thread Starter
Full Member
Joined: Jul 2003
Posts: 123
Likes: 1
From: Qld, Australia
The car cost me $AU8500 which is about $US6600. A lot of you guys probably think that's pretty expensive but for the amount of money that's been spent on the engine and wheels alone, I think I got my moneys worth.
Soft & Wooly
Joined: Jan 2007
Posts: 291
Likes: 0
From: Lakewood, CO (formerly Seattle)
I'd think the best thing you could do is switch from the straight pipes to a tuned header, and get a better muffler, a tuned header + presilencer + open muffler won't be louder than the straight pipes + stuffy muffler and will make more power. But if you are driving a bridgeport it's just going to be loud. Tuned header uses the pulse from one rotor's exhaust to help suck the other rotor's exhaust out and works better than straight pipes where the motor has to push the exhaust the whole way.
Also concur with lower octane gas and maybe fiddling with the timing or mixture... make sure your carb is working at top efficiency. Get a wideband O2 sensor and see how your AFR is when you make your dyno runs.
Also concur with lower octane gas and maybe fiddling with the timing or mixture... make sure your carb is working at top efficiency. Get a wideband O2 sensor and see how your AFR is when you make your dyno runs.
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