Non-turbo 428rwhp FD build up and history
#51
So I searched around and found what I consider a excellent turbo 13b dyno chart. This one is from 2008 and member imluvinit. Hope he doesnt mind Its on a dynojet which reads close to a dynapack. So I accurately drew his TQ and HP over my chart. It would have been nice if we both had started the pulls at 1500, to show the bottom end difference, but this is good enough.
Now working with and building/driving all types of rotary engines for years, I know exactly how each setup feels and performs. So lets break down the facts. The 13b in this chart is at 15 psi. Making the 13b a 5.2 liter. My 20b is a 3.9 liter. Only way for a 3.9 liter to make the same power is high rpm. More rpm doesn't mean its better. Total power is what wins. Now daily driving, n/a 20b has more power under 3500 rpm. Making fun for traffic and light to light experiences. Also easier to accelerate at any point. The power will just smoothly pull from 3500 up. On a racetrack there is no "rush" or extreme torque rise. Makes for a much more predictable engine in mid- corner. Now which engine is faster? Tough call. Going to 8.5k and shifting in the 13b will place rpm at 5,000 for second gear. 5k in the turbo 13b is 270 horsepower. The n/a 20b going to 10k and shifting will place the rpm at 7,000 for second gear. 7k is 320 horsepower. So +1 for n/a 20b. But if you look at overall power the 13b has 400rwhp for 2,000 rpm. N/a 20b has 400rwhp for 1500rpm. +1 for 13b. End answer would be it is a toss up.
Now working with and building/driving all types of rotary engines for years, I know exactly how each setup feels and performs. So lets break down the facts. The 13b in this chart is at 15 psi. Making the 13b a 5.2 liter. My 20b is a 3.9 liter. Only way for a 3.9 liter to make the same power is high rpm. More rpm doesn't mean its better. Total power is what wins. Now daily driving, n/a 20b has more power under 3500 rpm. Making fun for traffic and light to light experiences. Also easier to accelerate at any point. The power will just smoothly pull from 3500 up. On a racetrack there is no "rush" or extreme torque rise. Makes for a much more predictable engine in mid- corner. Now which engine is faster? Tough call. Going to 8.5k and shifting in the 13b will place rpm at 5,000 for second gear. 5k in the turbo 13b is 270 horsepower. The n/a 20b going to 10k and shifting will place the rpm at 7,000 for second gear. 7k is 320 horsepower. So +1 for n/a 20b. But if you look at overall power the 13b has 400rwhp for 2,000 rpm. N/a 20b has 400rwhp for 1500rpm. +1 for 13b. End answer would be it is a toss up.
Last edited by GtoRx7.; 01-13-11 at 07:51 PM.
#52
In the Garage
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This thread is another great example why I like this forum so much. Quality builds that continue to teach me about not only about the rotary engines, but engines and power production in general.
This is a great thread. Very impressive build. I would love to hear that thing in person screaming at 10k!
wow...just wow...
This is a great thread. Very impressive build. I would love to hear that thing in person screaming at 10k!
wow...just wow...
#53
Thanks Gordon, the dyno chart was a lucky find Technically the 13b turbo with massive amounts more torque between 3500 and 8000 rpm would be the victor in a low rpm corner exit. Even a poor driver would not be below 3500 in any corner taken at speed. However this is a situation where the charts cant explain. As you already know, a turbo is a rubber band between foot position and power hitting the wheels. So in real world pratice, getting the turbo to spool mid-corner, but not over estimate is extremely difficult. Very large downforce, good driving and tire size can "absorb" this massive torque impact and be made fast. But for us mere mortals a linear power delivery will be "instinctual".
For anyone else reading, the n/a 20b does not possess a sludge hammer, pull your eyes into the sockets acceleration. Like Gordon and T-von and others have explained it is a less violent, linear pull. I would say it is faster than it feels. One last consideration is 99% of n/a 3-rotors will not rev to 10k. A stock oil pump and metal based seals in a 20b *should* not be taken over 8500. 8900 if everything is balanced and every last oil mod performed. Anything past that is playing with fire. Drysump and ceramics or carbon seals are the next step to see 10k reliably, among countless other things. For comparisons or people planning on building a 20b keep this in mind. I tell my customers this all the time. The difference between a 8500rpm and a 10,000 rpm 20b is double the cost!
For anyone else reading, the n/a 20b does not possess a sludge hammer, pull your eyes into the sockets acceleration. Like Gordon and T-von and others have explained it is a less violent, linear pull. I would say it is faster than it feels. One last consideration is 99% of n/a 3-rotors will not rev to 10k. A stock oil pump and metal based seals in a 20b *should* not be taken over 8500. 8900 if everything is balanced and every last oil mod performed. Anything past that is playing with fire. Drysump and ceramics or carbon seals are the next step to see 10k reliably, among countless other things. For comparisons or people planning on building a 20b keep this in mind. I tell my customers this all the time. The difference between a 8500rpm and a 10,000 rpm 20b is double the cost!
Last edited by GtoRx7.; 01-13-11 at 09:19 PM.
#54
This thread is another great example why I like this forum so much. Quality builds that continue to teach me about not only about the rotary engines, but engines and power production in general.
This is a great thread. Very impressive build. I would love to hear that thing in person screaming at 10k!
wow...just wow...
This is a great thread. Very impressive build. I would love to hear that thing in person screaming at 10k!
wow...just wow...
#55
Banned. I got OWNED!!!
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A stock oil pump and metal based seals in a 20b *should* not be taken over 8500. 8900 if everything is balanced and every last oil mod performed. Anything past that is playing with fire. Drysump and ceramics or carbon seals are the next step to see 10k reliably, among countless other things. For comparisons or people planning on building a 20b keep this in mind. I tell my customers this all the time. The difference between a 8500rpm and a 10,000 rpm 20b is double the cost!
#56
Defined Autoworks
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Your basically right when talking about a street type car, unless the person specifically wants n/a. The biggest problem with a turbo 20b on a race track is keeping it cool. The turbo 20b would get hot very fast in a circuit race setting. Both set-ups are amazing. Defined did a 650 wheel 20bt for a customer to use as a daily type cruiser. That car pulled so hard to red line, I thought I was going back to the future.
#57
Rotor Head Extreme
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So so true! It's so smooth with it's delivery that it's acceleration is really deceiving. I'm still trying to get use to it. I keep thinking I'm going to get the top end rush from my twins but keep telling myself it isn't going to happen. I love how the power doesn't drop off at 7k like before. I haven't dynoed mine yet but it feels really close to my M5 (and I'm still on stock ports) . I usually get on a stretch of road and accelerate to a certain spot and see what my miles per hr is between both vehicles.
#58
So so true! It's so smooth with it's delivery that it's acceleration is really deceiving. I'm still trying to get use to it. I keep thinking I'm going to get the top end rush from my twins but keep telling myself it isn't going to happen. I love how the power doesn't drop off at 7k like before. I haven't dynoed mine yet but it feels really close to my M5 (and I'm still on stock ports) . I usually get on a stretch of road and accelerate to a certain spot and see what my miles per hr is between both vehicles.
#61
Rotor Head Extreme
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That was one of my goals but I'm not sure. Based on my time line I don't think I will be finished with everything in time. Engine is currently out so I can complete my intake. I'm also having to fix some faulty coolant seal passages with my engine. Even though I have a "D" series engine, I have some bad factory castings and every thin metal around some of my inner coolant seals channels. One by one there breaking causing my engine to drink coolant. It's nice that I know how to repair them and this should take care of my hard hot starting problems. Once back together, I have to test it out for about a month to make sure it works like I want. Then I have to pull it out again so I can paint everything (body, engine bay, motor). I'm hoping to have everything done by April. That doesn't leave me with enough time to make sure it's gonna be reliable enough to make that drive from west Texas. I'm definitely going to Sevenstock though.
#64
Defined Autoworks
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Ptrhahn... When you think about it, you are kind of always tuning for torque, since hp is a derivative. So, it might be possible to tune for torque somewhere else -- to modify the torque curve -- somewhat, but I'm not sure you want to. Maybe I'm way off here, Peter, but I find when I drive a strong NA like this that it feels and acts way more torquey than the turbo motor. I don't know if you've driven one, but you ought to. I am tempted to say something stupid like, 20b NA horses are somehow different. I won;t, but I'm tempted. Take a look at the torque curves, realizing that the 20b is essentially flat down to 1500, while the blown motor keeps falling. Also, the power is so instantaneous when you even move the pedal. There will ultimately need to be some track days where the 20b na runs against blown motors and we can see how the times work out.
Gordon
Gordon
Once again I don't think there is a better or worse, just different. I would prefer an n/a 3 rotor my self, due to the reliability. I really believe the engine set-up of choice is all the driver's preference. A good example of this would be when Logan and I went an auto cross. Both of us were basically running identical times all day. If one of us got ahead by a slim margin it was due to a change in the way we went about the course. The biggest challenge of driving a turbo car is keeping in the engines range, if you mess up big or miss a shift you know it.
#66
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Originally Posted by GtoRx7.
; The difference between a 8500rpm and a 10,000 rpm 20b is double the cost!
But you made 400hp@8500 which you say is the limit for most 20bs. You make 27 more horse power (427)@9500, but needs to double the engine cost. To me thousands of dollars for 27 hp is pretty pricey.
Would a better approach be to go 4-rotor NA that only spins to 8500?
---already dry stump
---already making custom headers
---already making custom intakes - now you could use that middle throttle body
I think with what you are doing an NA 4 rotor would be ridiculously bad ***. The torque would be that much better.
Like I said before I love your stuff---I wish more vendors would design to this level
#68
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I understand.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
#69
Defined Autoworks
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I understand.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
#70
Rx7 Wagon
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http://www.pulseperformancere.com/index.php?page=videos
Couple 4 rotors on this page. They are over the top. I like Logan's 20b personally. At least it's remotely streetable.
Couple 4 rotors on this page. They are over the top. I like Logan's 20b personally. At least it's remotely streetable.
#71
Do a barrel roll!
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Just wanted to add a few points to back up Logans post. FOr years Ive wanted to do a N/A 20B FD. Re-Amemiya's GT300 cars were always my favorite, and ever since I saw/heard them I knew this was something I wanted to do. Thankfully someone like Logan came along and did alot of the R&D and put alot of info out that made this a possibility for me. Im having him build my engine, so hopefully within the next year or so we will have some solid numbers on what a sideport only engine can put out. And to all those inquiring about the torque, I think your worries are unfounded. Ive ridden in Logan's FD, and believe me it pulls strong even down low. This may not be for everyone, and those of us who pursue this route know that ultimate power/torque isnt what this is supposed to accomplish. Without the P-ports, you can just about makde as much power as you could with a stock twin/14-16psi FD. But the way the power is delivered, the sound, and the feeling is what makes it worthwhile. That and not constantly staring at boost, egt, having to run AI, etc..
#72
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Great work Logan. Saw the car at the Street Life Tour and was in awe. Glad I found the build thread since I didn't get a chance bs with you guys before I had to take off.
#73
Defined Autoworks
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http://www.pulseperformancere.com/index.php?page=videos
Couple 4 rotors on this page. They are over the top. I like Logan's 20b personally. At least it's remotely streetable.
Couple 4 rotors on this page. They are over the top. I like Logan's 20b personally. At least it's remotely streetable.
#74
Oompa Loompa Doopity Doo!
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Thanks Gordon! Between your Rx7 evolution with refined n/a power and these results, people will have a better understanding of 3-rotor capabilities. The slight dip was a o2 sensor having difficulty reading AFR's while on the dyno, so it was a bit richer there. I was in a rush so didnt get a chance to tune it further by ear. Looking forward to building you a set of headers
Thank you
I would like to take it to seven stock, so maybe see you there?
Thank you
I would like to take it to seven stock, so maybe see you there?
#75
*10k 20b ---------*8.5k 20b----------Difference
6500 rpm 270hp 5000 rpm 180hp -- 90hp
7000 rpm 320hp 5500 rpm 225hp -- 95hp
8000 rpm 365hp 6500 rpm 270hp -- 95hp
9000 rpm 420hp 7500 rpm 340hp -- 80hp
9500 rpm 428hp 8000 rpm 365hp -- 63hp
1000 rpm 420hp 8500 rpm 400hp -- 20hp
So you can see that in real life the extra 1500 rpm gives an additional 90 horsepower gain average over the majority of powerband.
I understand.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
I guess my point was - there is already tons of custom fab work being done.
Instead of putting money in to spin it another 1500 rpm spend it on a 4 rotor e-shaft and center plate.
I guess we would have to see how much Defined would charge for a 8500rpm version and how much for a 10K rpm version.
I can't remember his name right now, but the last 4 rotor build cost about $35K
If Defined 10K 3 rotor cost $28K then I would save my pennies for them to build me a 4 rotor. And they would be my first choice after reading this thread.
Sorry - I hope I don't come off as a troll trashing this thread.
Quick rundown of the three options, engine only-
8500 rpm high comp, balanced, ported 20b- $11k 246rwtq 400rwhp
10000 rpm high comp, balanced, drysump, ceramic 20b- $18k 246rwtq 430+ rwhp
8500 rpm high comp, 4 rotor, drysump 26B- $23k 340rwtq 530rwhp
So for $5,000 more on engine, and roughly $1200 more on intake and exhaust, the 4 rotor is $6,200 higher expense than 20b. Additionally the mods to possibly make the 20b into a 450-480rwhp engine are not much more. I just need development time
Last edited by GtoRx7.; 01-16-11 at 04:49 AM.