20B ultimate power
 

Hi guys,

I will shortly be working with some guys who have a 1350 bhp, 2700lb, .35cd car, and will be attempting to build a competitive FD in my spare time. I had been planning to keep my 20B for this purpose, probably with the intent of a turbo-PP build. Recently I have been wondering if the 20B is capable of reliably producing this power level though. Most 20B builds (mine included) end up making 7-900bhp (~600-750rwhp).

I am not sure if this is due to any limit of the engine or has more to do with the limit of usable power in an unmodified FD chassis...

Does anyone know of any 3 rotors out there that consistently output over 1000whp?
I am less interested in drag cars that are rebuilt after 3 runs, mine will need to last at least 5000 miles, but even those ones let me know...

I may end up having to build a quad rotor for this application but I would much prefer to stick with 3 due to packaging issues as well as already having a sorted 3 rotor.

I suspect this is it. Another thing is that the kind of guys who are looking for a 1000whp usually go with an easier platform for that application, namely a V8 car with solid axle (Camaro etc).

What kind of fuel are you looking to run? If you are willing to go E85 your options expand considerably.

99% of the people that are making 1000hp+ with there 20b set up don't post up on the forums or the web. AU and PR rotary oriented shop are the first places you will want to inquire about your needs.

Hope that helps.

Roberto Gonzalez from Naranjito, PR has laid 1186whp from a 20b in his gray RX-8. Its a beast. He did this with a Garrett GT-55 and at only 24-26psi. At 14psi its in the 800whp range. The catch is that the mods are endless, It has semi-peripheral ports that open and close at certain RPM/boost levels and that is just the beggining. It idles perfectly (only a streetport on the primaries/secondaries) but has the crazy upper end of a semi-peripheral engine.

Considering this is a street driven car with A/C, P/S etc... I think your goals are definitely attainable.

Best regards,

Chris

If anybody can do it, it's dudes from PR haha

i'd have to guess most aren't breaking any records with the 20B due to it's length and twisting factors. the engine virtually needs to be pinned if you are looking for anything over 700 semi reliable horsepower from it. even then the standard pinning process isn't ideal for anything over a 2 rotor, custom full length pins need to be fabricated. studs for such a long engine simply won't cut it.

a dry sump with a thick steel plate might also substitute pinning but that is a stretch unless you oversize the pan holes. but most you will see that are built have a dry sump system which will help dramatically with keeping the deck level.

+1

I think the limit is the e shaft flexing. You may make over a 1000 hp for a very short time. Those race teams rebuild after 2 or 3 track days lol

1bad20b already proved this is a limiting factor.

I don't have any 'needs', other than maybe some advice, as I will be doing this myself. I am more worried about the eshaft than the block, as I will be running high RPM, so less torque on everything, but more side load on the eshaft. The goal will be 1400bhp@10,500RPM. I am moving in the next couple of months, once I see what kind of garage setup I end up with I will start putting together my engine dyno, then we will see what happens. I'd like to have this in the car and driving in 2 years or less.

When you mount engine at the rear plate rigidly to chassis ie with huge plate, there can´t be any twisting. Just think about it, there is no leverage which would act on the block itself and "twist" it.
So lets consider this is no problem.

Sheer combustion forces trying to push rotor housing outwards on plug side can be somewhat coped with doweling/studding till we start cracking plates. Also IIRC someone from PAC over ausrotary mentioned main benefit of Turbosmart billet plate - no cracking around stationary gear which is probably main culprit of really high powered 20Bs.

https://www.rx7club.com/showpost.php...1&postcount=63

This is also interesting but in the light of recent development, I can´t draw simple conclusion. Most powerful 20B on the planet is probably in Australia and its long block with billet thick plate or at least this is what they tell us:lol: Pica also put down some serious MPH and block is factory based. Short crank 3 rotors are IMO best design but they probably suffer from very same culprits of factory pieces.

Its simple - rotor housings are not rigid enough to maintain their shape which in turn cracks side plates. And stationary gear support itself failing from axial loading. At what power level it happens, I don´t know:blush::lol:

my 2cents, highly don't recommend reeving it that high, that is why alot of people brake the e shaft i don't take mine more than 7000-8000, you don't have to rev the 20bs to much to make power, i made 831 to the wheels so that its close the 1000hp to the flywheel on c16, also would recommend using alcohol if possible because you will be able to make around 1000hp to the wheels with around 21-22 psi. you should be able to accomplish that task but everything needs to be reinforced because we are talking a factory engine that was made to only handle around 350. so pining, and all the other mods are necessary. Hope this helps and good luck.

Only thing that is going to get these things reliable is a 3 piece e-shaft with double splined lobes and a guru style, mid rear side housing bearing. In addition to the full length pinning or doweling.

I say double splined because I have seen one that sheared and stayed together for a 3 -5 degree offset. It literally looked like one of these cam offset woodruf keys you can buy for v8 cam gears. lol.

You can get the motor there, but you have to figure out the trans, rear end and the other factors outside the motor as well. This isn't just a build the motor and be done quest. It is a build an entire car quest. I am in the middle of a similar 20B project for a member on here and if he wants to chime in I'll let him feel free and fill in the parts I am leaving out.

aftermarket ford 8.8 independent and Borg Warner ZF6 is what I will be using. Not sure about the ultimate power handling of the ZF, but I will give it a try before I switch to a T56 or custom box, since I already have the ZF. Another reason for my high RPM strategy is that I can run a lower rear end ratio and reduce torque on the rest of the drivetrain.

My only issue with building a 10k+ turbo 20b, is the apex seals. The only two seals that will not chatter at high rpm are carbon and ceramic. Obviously the carbon cant take boost, but the ceramics are so fragile with any detonation. When running upwards of 1000+rwhp, slight detonation during the teething process is almost to be expected.

hmmmm, Say if you had a turbo motor that's already balanced and race clearanced, running one of the softer seals like ALS or Goopy, running drysump, what do you think is the highest rpm you'd rev it to?

:D

+1 Great goals though, and we hope you accomplish them!

2mm apex seals, 8900 max. Really 8500 is the happy zone, but numerous people have done 8900-9000 for extended periods of time (including me).

It really is more than jsut the motor the rest of the drivetrain will break unless you build it. I question how long most t56's will hold without some reinforcement at 1000whp. the diff axles and drive shaft are also an issue I still on kaaz unit with rp axles and a magnum t56 that was completely built by rpm transmissions. we will see how that goes. as far as the motor I think the eshaft is breaking more from rpm's rather than horsepower. the motor naturally twists a bit and the front rotor housing has to be allowed to float a little bit but the fact that the motor is longer means a fulcrum effect on the rotating assembly and the fact that it has a longer shaft and an extra rotor makes the fulcrum effect worse. my thought is to keep the rpms at a decent level and to add a third motor mount to the large fat iron to keep the motor from flexing as much as well as dowell pins lightened and balanced rotating assembly as well as a few other tricks... :)

Another thing to consider is what power you really plan on using and how quickly can you get it online and can you stick it. people have ran deep into the nines with a little over 650 why people think they need 1000whp on a street car is beyond me. but to each his/her own.

If this is your argument then why have 650hp or 500hp or 400hp why not leave the car stock. I think we should all push our limits and find what 20b are capable of producing. I will be going back to the dyno perhaps in a couple of month to go over the wheel 1000hp. perhaps some people are not satisfied with running 9 maybe they want to run 8 or 7 on a street car. Specially if the v8 can do it why can we. Long live the rotary power!!!!!

My project will be more about high speed, where power is really necessary. I don't care about 60ft times, I want a 100-200mph time.

Rz and Patman I apologize if I offended you guys I just think that 1000whp in a car this light would be difficult to use in a "street car form". However if you have found a way to hook I'm excited and would love to know how. I'm always excited to learn new things. As far as running 7's in a street car you will be fully caged a parachute and probably wheelie bars and possbily a tube chassis. It could be Street legal, maybe but not much of a car I would want to cruise around town in for too long or drive on the highway or an off ramp that does any 180 curves. As far as 100-200 mph times I understand the need for big power. but it does come back to traction again. A good friend of mine is running a twin turbo viper from underground racing with automatic transmission and its tubbed with 16 inch wide race slicks and more weight to push the rubber into the pavement. He runs this car on the highway and texas mile and he still has traction issues even with boost by gear from the motec setup. I just believe that a slower spooling turbo and a large possibility of losing traction will hurt your times more than a smaller power number that comes online sooner and hooks . But If someone can hook that large of power then hats off to them I truley have respect for someone that can do that .Again not trying to step on anyones toes just going from experience but hey I could be wrong. I'm not perfect. and Rz I agree "long live the rotary power!" :)

Dont worry you didn't offend me! So far i haven't had any traction problems since my sponsor Mickey Thompson provided the awesome tires they make. With my old Nitto i did have problem but the street drag from MT are amazing perhaps you should talk to your friend and have him try them. I did alot of research and make alot of changes in the suspencion to make sure i had good traction. Alot of people just make the power and forget that they have to plant it to the floor. Cool discussion.!

Alex

Quit rocking the boat in the 20b forum and ill get your car done this month and well have some fun.