Non-turbo 428rwhp FD build up and history
01-12-11, 11:21 PM
#32
As Gordon mentined the higher compression seems to be a henderance. I have never recommended them to customers for the fact of being unproven. Carlos Lopez found about 2-3% more power using Rx-8 rotors in full p-port engines. Otherwise no good news on that front. Asking a 20b to lay down 500 is the same as wanting 333rwhp from a 13b. And without a full p-port or bridge port. And all with 93 octane gasoline! Full drag race guys are running 320-330rwhp with methanol and large p-ports. Serious challenge!
01-12-11, 11:29 PM
#34
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Very impressive.
Especially the modified stock sub frame running a dry sump and rollcage.
i would love to see a video of it running up to 10k on the streets from inside the car.
Especially the modified stock sub frame running a dry sump and rollcage.
i would love to see a video of it running up to 10k on the streets from inside the car.
01-12-11, 11:41 PM
#37
Forced induced engines will always have increased torque under boost because, you are virtually increasing the displacement with every psi increase. The principle of making hp is exactly the same between the two kinds of engines. The more air you can cram into the combustion chamber for any given rpm, the more torque/leverage your going to create against the crank/e-shaft during the combustion event. 13b based rotary's in general don't have a long stroke on the shaft like a typical piston engine does. That's why Mazda is going with the larger stroked 16x. Trust me, there's more than enough torque in this kind of set-up to spin tires in a light weight car. Hell with mine I can break the rear tires loose rolling on the throttle at 5mph in 1st gear with stock tires. That never happed when I was stock and twin turbo. With the stock turbo engine, you having to wait for boost to build; not so with NA as throttle response and torque delivery is instant. This thread is a perfect example of what lies ahead. As more & more R&D goes into discovering NA potential, things will really get interesting for future rotary applications. As I said numerous times before, Mazda can't do it all by themselves and need our help. My contribution to this cause is nearly finished!
Great job Logan,
01-13-11, 12:13 AM
#39
Okay, torque is a function of many things, but the largest two are displacement and efficiency. A 3-rotor is 3.9 liters in the piston world but rotaries are less efficient. At 290 flywheel torque, my 20b is 74ft-lbs per liter. Camry at 70ft-lbs per liter. A VERY efficient piston engine. The almighty new corvette z06 is at 67ft-lbs per liter. Hmmm the picture is more clear now...
So why do turbo engines have more? Boost is displacement. Period. Add 14.7 psi to any engine and the torque will almost always double. Why? Twice the normal atmospheric pressure. Twice the filling volume. Lets take a average turbo rotary. At about 14.7 psi most are around 300rwtq. Which is 355 flywheel. 355ft-lbs/2.6 (13b displacement) and we get 136ft-lbs per liter. Take that and divide by 2 (to make it back to atmospheric) and we get the 13b turbo at 68ft-lbs per liter. Seeing continuity?
Last we get to mix in RPM. ANY dyno chart, and I mean ANY will have horsepower and torque IDENTICAL at 5252 rpm. Why? Its in the math. As such ANY chart will also have exactly double the TQ vs HP at 2626rpm. Furthermore the HP will be double the torque at 10,504. These are the rules of math. So the higher the rpm past 5252 the higher the horsepower will be vs. torque. Its does NOT mean the engine has no torque. It just means the engine can hold torque for a very long period of time. (which is a faster engine)
So you can actually see my good ol' 20b is producing fantastic torque, espically for a rotary. And I gladly will allow my car to be judged only by the torque, many people would get their feelings hurt
01-13-11, 12:49 AM
#40
Damn, I just learned something. I always wondered what an engines displacement would be once boost pressure was added. It never occurred to me that adding twice the atmospheric pressure (14.7 psi) virtually equals double that engines displacement. So at 14.7 psi, a 2.6L 13b would virtually have the displacement of 5.2L. Am I looking at this right?
Yep! So much for the torque less rotary. LOL! Funny how things change when we start actually comparing rotary to their equal displacement counterparts.
01-13-11, 08:44 AM
#43
Great build, and great thread! 
Very impressive! 
As far as the torque argument,
. You guys got it covered. When you look at the amount of TQ our motors produce per liter, it's seriously impressive. And I imagine in a car this light, the torque is plenty sufficient.
Another (simpler) way of looking at it, is that the equation for torque is simply the amount of force applied multiplied by the distance from center at which it is exerted (or TQ = F x D). You're not changing the distance from center (the stroke) at which the force is applied, but you are increasing the force GREATLY by forcing in a higher, more compressed volume of air into the combustion chamber. Volumetric efficiency increases, along with the potential energy of the mixture before being converted into kinetic energy. In layman's terms, higher combustion pressure (higher force) = higher torque.
Anyway, congrats on the build.
Looks like it's coming along beautifully!
Very impressive! As far as the torque argument,
. You guys got it covered. When you look at the amount of TQ our motors produce per liter, it's seriously impressive. And I imagine in a car this light, the torque is plenty sufficient. Another (simpler) way of looking at it, is that the equation for torque is simply the amount of force applied multiplied by the distance from center at which it is exerted (or TQ = F x D). You're not changing the distance from center (the stroke) at which the force is applied, but you are increasing the force GREATLY by forcing in a higher, more compressed volume of air into the combustion chamber. Volumetric efficiency increases, along with the potential energy of the mixture before being converted into kinetic energy. In layman's terms, higher combustion pressure (higher force) = higher torque.
Anyway, congrats on the build.
Looks like it's coming along beautifully!
01-13-11, 09:59 AM
#48
You folks should egg him on for a ride when you get the chance. You will think you are ridding in a single turbo set-up, until it keeps pulling to 10k, and then you remember it's n/a. This car is seriously fast, probably to the point where you need to think about where you floor it on the street. Im sure it would not take much to convince Logan to give out rides.
01-13-11, 11:47 AM
#49
I'm not sure I know FDWarrior out there, but he's obviously ridden in Logan's car and he's only "hinting" at how a strong NA motor feels and pulls. I had a 1994 Ferrari 512TR and one of the great giggles it -- and other Ferrari big 12's -- have in common is this linear pull from anywhere in the rev band to 7500. There's no "sweet spot" or surge as cams come on. The thing just pulled at what seemed like the same rate of acceleration everywhere. The NA 3 rotors are exactly like that, but they pull even longer, since you can rev them to 9,500-10,000 rpm. And, its linear all the way. So, at, about 7,500-8,000 when a built singe turbo is running out of juice, the NA is still pulling like a ****. Very different. Very addictive. You need a ride.
I am hopeful with the changes I have made to be making only about 360 or so whp and still hope for 10 or 15 hp more. I have stubbornly refused to semi pport my engine, because of my (silly?) feeling that it will make my idle less-refined. BUT, even with less hp than Logan's, my car has that same torque anywhere thing that Logan's has and is remarkably faster than you would think, simply comparing NA 20b hp and single turbo 13b hp... They're not the same at all. You need to overlay a 20b dyno graph with a 13b single graph and you'll see the difference in a heartbeat. It will look like the singe turbo simply has no power except in a very narrow band. (Can some photoshop junky do this and put it here or in another thread to show this. I think it would be valuable.)
Fritz... You're right.
Logan... Check your email?
Gordon
I am hopeful with the changes I have made to be making only about 360 or so whp and still hope for 10 or 15 hp more. I have stubbornly refused to semi pport my engine, because of my (silly?) feeling that it will make my idle less-refined. BUT, even with less hp than Logan's, my car has that same torque anywhere thing that Logan's has and is remarkably faster than you would think, simply comparing NA 20b hp and single turbo 13b hp... They're not the same at all. You need to overlay a 20b dyno graph with a 13b single graph and you'll see the difference in a heartbeat. It will look like the singe turbo simply has no power except in a very narrow band. (Can some photoshop junky do this and put it here or in another thread to show this. I think it would be valuable.)
Fritz... You're right.
Logan... Check your email?
Gordon
I was with logan and peter at your meet about 2 years ago, we stayed in the tower. I had the red fd at the time. I don't want to hype up the way the car feels, but people just need a ride. I find when you tell some one how fast a car is then it's always over hyped in your head, no mater what hp the car has. Both engine set-ups have there strengths and down falls though. I really like the n/a for the reliability, and ability to perform in an endurance race situation. The n/a rotary can not be beaten in an endurance race situation, just ask everyone who had to race against the 787b. I believe mazda stated after tearing down the 787b 4 rotor that it could go for another 24hrs. The n/a route is really a great path to take.
