After some thinking I decided that it will be worth to have 20B option. Fortunately I've got 3D model of rotary engine many thanks to Paul Lamar (not detailed but right external dimensions). It will do for packaging purpose.
One "2 rotor..." picture it's visible how nicely renesis packs in - far behind front axle. Looking at "20B..." picture it's obvious that engine bay requires redesigning. It will be nessesary to increase the wheelbase a bit. This leads to redesigning the hood and fenders and may be overall exterior to keep proportions right.... This means crazy amount of work and money is scrapped for good. It will also require to use rear mounted transaxle to compensate increased weight of 20B. Arghhh!!! This 20B is freaking long! Obviously this option is going to be much more expensive. Also those 20B's are not easily available...

So... From every point of vew it seems that 20B should be forgotten. But it is hard to resist. As far as I understand with FI, safe 500hp is a norm?

What do you think about it? Does it really worth it?

Cheers
Ted

Arghhhh!!! I can't upload images! When I click "Manage attachments"

 

If you're looking for 500hp, you have to go 20B.
________
Sexextreme12

 

is 500 hp your goal? if so id say 20b. i would imagine you could maintan a signifigantly better hp/torque curve with a 20b vs a renesis. id love to see a 500hp reni though.

it all depends on what you want to make: a fast turboed sports/tuner car or an out right supercar?

 

Base model will definately use FI Renesis. Goal is reliable 340rwhp with fast spool up. I'm not really sure if it's proven possible yet so may be final numbers may be more modest.
20B is an option for those who want max performance and don't mind spending.
How ever even at this stage redesigning the chassis so it can take 20B requires lots of work (and lots of work and money put in previous work will be wasted)

This is why I'm asking myself (and forum members) does it really worth it. 20B's 500hp mark that I menationed was just a guess. It seems that there are few RX7 conversions that put less and some that put more. I also think about twin screw S/C mated to 20B... mmmm that would be nice. I wonder if anyone heard of such set up tryed?

Cheers
Ted

 

you should check out the puerto ricans threads on here. they have atleast one 20b rx8 running around and could help you with this

 

mazsport is installing a 20b in a customer's car right now. I don't seem to recall any talk about chassis lengthening though.

 

N rider89,
I was just reading that 3rotor in PR thread. This is impressive!
Thank you for pointing me anyway.

Misk101,


This is not an RX8. Here's a link https://www.rx8club.com/series-i-major-horsepower-upgrades-93/thought-share-some-pictures-105999/
In my case 80mm wheelbase lenthening is required because I need to keep engine within wheelbase at all costs. More so (as said in previous post) to offset added weight on front axle 20B option will rquire rear mounted transaxle - like it is done on Porsche 944 and Ferrari F550 to name a few. This car is designed as a race car - thoughts like "90% of clients would not be able to tell the difference between 52/48 and 48/52 weight distribution" are not accepted. It's like our previous chief mechanic which was fired for saying "This kid can't drive properly anyway. Why should we die over this damn formula if it's not going to make any difference?" Answer was - "Our job is to give him best possible equipment that is capable of winning the race. NO MATTER WHAT"

How ever I already redesigned front subframe so it can take 20B (In case a client is WILD enough" and it looks that to fit nicely. It will require a custom bellhausing to cover flywheel and tween plate clutch (smaller diameter than OEM) and mate to torque tube connecting clutch to transaxle.
Redesigning exterior panels will take weeks thought....

Cheers
Ted

 

wow a looking good project! keep us with the updates!

 

I can't imagine the car you're building with a 3 rotor. The hp/lbs ratio was already very good with the Renesis Turbo...with a 500bhp 3 rotor, you'd probably give someone a heart attack...

 

Tudor...whats your timeframe for the project?

I assume it will take a long time, so I would suggest an FI Renesis which by then will be nicely worked out.

Everyone here (with good knowledge) suggests its a better motor, and If your base one will be Renesis, it makes sense to make the Hi power version renesis too, and it will make it easier allround for economics and supply.

If mind you, you want a car finished by this summer then get a 20b I guess...?

 

even if he started a month ago, i'm guessing at least a year before the protype is finished.

after enough interest has been generated, maybe another year before it'll go into semi-custom production?

either way, we're looking at years (2-3 minimum) before we can get one here.

i hope i'm wrong!

 

yeah basicaly thats what I was figuring as well, hence my belief that the Renesis will evolve to where he wants it to be by then...

 

renesis will never be able to make over 400whp reliably. by reliably, i mean 50k miles without any issues. compression is just too high for any daily highly boosted turbocharged applications. if he's shooting for 300whp, i think it can work out wonderfully. anything beyond that, i still think he should look into either 3rd gen 13b or a detuned 20b.

or he can be our hero and design us a lower compression rotor... but like he said before, he isn't an engine guy.

if the buyer wants to tune the renesis to the brink of detonation at say... 450whp somehow few years down the line, well that'll be upto the buyer.

 

Tudor,
Have you thought about running a 2 rotor rotary (13b or Renesis) with a supercharger and a turbocharger in series? The supercharger basically creates a larger engine out of the 2 rotor such that you could run a larger turbo without running into spooling issues. A supercharged 2 Rotor is as far as the turbo is concerned the same as a 20b. In addition the engine can be highly ported, since the supercharger ensures that the intake pressure is always higher than the pressure in the exhaust.

The point is 800kg is an extremely light car and rather than spoil this light car and move the center of gravity by placing a heavy 20b engine in there, you'd be better off with a lighter but twin-charged 2 rotor.

If you'd even install an axialflow supercharger you'd add less than 20lbs to the entire set up (a third rotor weighs much much more).

 

Thanks for your suggestions guys. 20B is just an option. Murena is designed around FI renesis.

https://www.rx8club.com/showthread.p...9&page=1&pp=15

Thanks
Ted