GtoRx7.

iTrader: (12)

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.

oo7arkman

iTrader: (2)

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...

GtoRx7.

iTrader: (12)

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!

GtoRx7.

iTrader: (12)

Glad that all the great members and me can provide new info One thing great about cars and dynamics, you ALWAYS can learn more.

yzf-r1

iTrader: (1)

Yeah, 10k sounds like full race engine territory. A mildly turbocharged 20b seems like the best of all worlds to me: linear pull and extremely strong punch up top

FDWarrior

iTrader: (6)

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.

t-von

iTrader: (8)

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.

GtoRx7.

iTrader: (12)

It did go back, and we raced all the 70's muscle cars Such a fun trip.

Are you going to make it to DGRR? I have been wondering what a stock port n/a 20b would be like. We are scheduled to build one soon, but not sure when exactly it will happen.

Alex Rodriguez

iTrader: (137)

dude so we should start calling you "N/A king" and change the screen name that daily driver of yours has some impressive numbers too for re-n/a

GtoRx7.

iTrader: (12)

Haha thanks, n/a development is a passion of mine. Well rotarys both turbo and n/a. Just the n/a is so much more difficult, and thus challenging

t-von

iTrader: (8)

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.

ptrhahn

iTrader: (9)

I'd be curious if this could be tuned to produce more torque and less horsepower.

It's a fantastic achievement, don't get me wrong, but I'd be more interested in something that made over 300 ft/lbs of torque at the expense of say, 50 peak horsepower.

yzf-r1

iTrader: (1)

Supercharged 20b?

FDWarrior

iTrader: (6)

Thing is it's not really an argument or a vs. discussion. Both engines are from a different school of tuning. I hate the better or worse argument, I don't believe there is such thing as better or worse, it's what's better for the individual. The biggest thing to realize is that when on a track you are operating in an rpm range. When I auto cross I never get below 3500 rpm, and never go above 7000 rpm. My turbo engine still makes more torque than one of the highest tuned 20b, even at it's lowest point to MY redline. This fact does not make my engine "better", or the better choice. The real curve that you experience is the shape of the power curve. The tq is part of the equation that makes up power. My dyno graph (not posted and Im not posting it here, it's in my thread) holds power all the way to red line, it never falls at all, where the torque starts to flatline. So when Im driving the car its always on the pipe, instantaneous turbo thrust when I breathe on the gas. You can see on a graph where torque is overlaid to the boost, the torque and boost mirror each other. The key to a turbo car is to make the turbo not drastically drop boost in higher rpm, this will come in the quality of the set-up. A turbo will always bleed off some boost but you can decrease this affect, with a proper set-up.

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.

scotty305

iTrader: (2)

Thanks for sharing, it's fun to read through builds that get posted after they are already complete... nice not to wait for updates, and nice to know the car turned out well.

hades

iTrader: (4)

Love your designs so I hope I don't come off rude or as a hater.

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

Narfle

iTrader: (16)

Yeah, I think we'd all like a 4 rotor. But, it's a ridiculously long engine block. Long enough to mess with the car's dynamics or require firewall relocation.

4 rotors are also extremely cost prohibitive. Waaay worse than a drysump 20b.

hades

iTrader: (4)

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.

FDWarrior

iTrader: (6)

I know Logan pretty well, and he may or may not be contemplating a 4 rotor soon! I would save my pennies as well, those things are insane.

Narfle

iTrader: (16)

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.

Rxmfn7

iTrader: (4)

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..

fuztupnz

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.

FDWarrior

iTrader: (6)

That boat is my hero. I would trade my car today for it.

ImStillOnJava

iTrader: (30)

Awesome awesome build. I hope you do show up at Sevenstock, I'll be front and center to check this out!

GtoRx7.

iTrader: (12)

The 27 extra horsepower is not what makes it so much more powerful. Here is a comparison to explain. Lets say each engine achieves its redline, then shifts into the next gear. I will start each one at the correct rpm of second gear-

*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.


On a naturally aspirated engine such as this, more torque is EXTREMELY hard to get. So hard to get, that basically large engine design changes only result in 2-5ft-lbs gain. Its about saving pennies. The best of the best 20b full race engines with full p-ports (most efficient) are making 300-310 FLYWHEEL torque. That is 255-260 Rwtq. I can only hope to match this. My 20b is at 246rwtq, which is less than 10ft-lbs from the best in the world, and not using full p-ports. Once torque production is essentially maxed out (I will continue to try and get more!) The next challenge is to place it in the rpm range to make the broadest power. So in short, sure I can make the engine have less horsepower, but the torque amount will not get greater. Its not a trade that can occur.

No worries you are fine! I was planning on going 4 rotor after this, but honestly I have changed my mind. If we build a 4 rotor it will be in a different car, meant for a different purpose. Extra weight, location, heat, and expense in my opinion are not worth the extra power. It would be complex to explain and I will if someone requests me to post it. But in the end it just cant match this current setup of front/rear balance, lower CG and weight.

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