Bigus Dickus

Wasn't sure what the appropriate home for this thread would be. Oh well... OK, I'm a newbie to rotaries, so don't beat me too hard.

I've been searching this forum for a while now, and I've found some good information, but as with anything else it's scattered and sketchy.

What I'm interested in: I'll be building an Ultima within the next two years. If you're not familiar with the car, take a look at www.ultimacars.com for some background info so you know what I'm talking about.

It's a purpose built tubular space frame mid-engine high performance kit car (or they can assemble it for you). The chassis is designed for an American small block V8 (Chevy typically), but the factory can work with individual customers to tailor the build for his/her needs. Also, I have a bit of experience in custom car building, and would be capable of doing any chassis mods that are necessary. There is a bit of extra room even with a 350 V8 to begin with.

My goal is to put a powerplant in that's as close to 1000hp as possible and be semi-reliable (it won't be anything like a daily driver, but even as a fair weather weekend toy you don't want the engine dying after 10 hours of play time). The chassis has been tested to 1000hp.

I could start with an LS1 or (preferably) an LT5, increase displacement a bit, do a lot of head work and other work, and run light boost to get close. Obviously this is the easy route, but hell... it's been done plenty of times.

I'd like to have a rotary powered Ultima. I'm sure a 20B would fit, and there's probably room for a quad-rotor. So... here's my list of newbie questions ...

What is the weight of a turbo 20B?

From what I've been able to gather, a 20B should produce around 500hp without straining much. How far can that be pushed before it becomes more of a drag enging meant for one or two runs? I'm thinking at 700 or 800hp, reliability would go to *****. Am I wrong?

I've also gathered that quad-rotor engines can be had from a couple of specialty shops, or by piecing one together yourself using a specialty eccentric shaft. Any idea on the lenght of one of these? I've seen numbers around 600+ hp naturally aspirated for a knock-off 26B. I'm thinking this engine might get close to 1000hp with reasonable reliability running on low boost. I'm thinking $10,000 for the core engine, and then all the goodies (ECU, accesories, turbos, etc.).

Any guesses at what the pineapple racing engine should make on light boost? What about a quad built using an eccentric shaft from that guy in NZ (that's using a pair of 13B's, right?)? Any idea as to weight and length? I don't want to be heavier than a small block V8, unless the power is substantially more.

Remember, this is a purpose built mid-engine tubular frame that's not too difficult to modify... I'm not talking about an engine swap here, so don't flame me like those poor guys wanting to put a V12 in their RX-7.

Obviously, a quad-rotor won't be cheap. An Ultima project isn't going to be cheap regardless. If I could do the entire engine (just the engine, but fully decked with cooling, dry sump, ECU, turbos, etc.) for under $50k, I'd consider it.

A 20B would be much easier, and cheaper, but unless you guys convince me otherwise it's just not going to get the reliable power an LS1 or LT5 could make.

OK, and now to show my complete ignorance... what the hell is brige port, street port, mega super-duper port, peripheral port, etc.? I understand that these must be different housing configurations, but are they from different production engines, or just different mods?

Bigus Dickus

Anyone? Can you point me in the right direction perhaps?

spyfish007

Look up RiceRacing and his web site for porting information. If you want 1000 HP then consider a big turbo on a 20B and you should be able to hit your number. I don't know how reliable it will be. One thing to consider is this ... what tranny are you going to use to hold this power on any motor?

Greg

Ok, I dont see a car in that body and frame style weighing over 1800lbs. The Horsepower numbers you are looking for are not needed. 1800 lbs with 800 hp would mean you would be driving a 7 second car (1/4 mile). Not necessary. The most power I would go with on a car like that is around 450-500. Even then the controlability(did I make that word up?) in turning and street driving would suffer. I would recomend a street ported 3 rotor engine with the stock twins. The reason is because you have the 500 hp there on tap and if you need you can make 700 hp. I understand that you want to have huge amounts of horsepower but, do you want to run Huge slicks just to get the car moving? Cause I am pretty sure that 1000HP and 1800lbs would fry every street tire you throw at it.

Felix Wankel

Here are some ok port pictures.

http://www.mazdatrix.com/faq/porting.htm

Bigus Dickus

Thanks for the reply. The chassis is designed for a Porsche G50 5 or 6 speed. I know this transaxle can handle 500hp. maybe 600hp more or less stock, but I'm sure that pushing 1000hp would require some not too insignificant tranny work as well. Due to the mid engine design, there aren't a whole lot of choices... I think their recommendation of the G50 is probably the best candidate.

I'm a bit afraid of pushing 1000hp out of a three rotor. I know it can be done, but I don't want a motor that's on the virge of self destructing at any moment. If I settle for a lower hp goal, I'll be very much interested in a 600hp three rotor for reliability and low weight (and the sound ).

Bigus Dickus

Thanks for the reply.

I think the Ultima GTR weighs in around 2300 pounds with an iron block 350 (I believe it was iron block, they just revamped their site a few days ago and now I can't locate which engine that weight was with). The chassis isn't a lightweight drag chassis... it's more of a competition racing platform. Very strong, stiff, and safe. That weight is also with CD changer/sound system, A/C, heater, etc.

You're right though, 1000hp would probably kill any street tires under full throttle. I'm not wanting a drag car though. It's more a "can I do it" project, and for pure joy and bragging rights. I may very well settle for 500-700hp, but I'll aim high so that the end result is still outrageous.

My choices are to start with a stock LS1, LT5, or three rotor, or to build from scratch an aluminum block bow-tie racing motor, or venture out and have some quad rotor fun.

The quad rotor is really intriguing. I'm a mechanical engineer, and I really can't see a quad setup being outrageously difficult to build (tuning is another ball of wax). With so few moving parts, the biggest hurdle is the e-shaft, which it seems can be acquired from several sources.

Anyone know of the length or weight of some quad rotors? I've seen somewhere that pineapple racing's quad is "a little shorter" than the factory 26B, but what was the factory 26B? What about weight? Three rotor weight?

Bigus Dickus

I'm pretty well read up now on the 350 alternatives. Probably the best route there is a built aluminum block motor. I've got a good handle on the power and weight I'm looking at with such a motor, and what the costs will be.

Can someone give me a rough ballpark for a three rotor weight, turbocharged of course (single or twin, whichever seems to be the best approach)? I can take a guess from there what a four-rotor might weigh in at.

aZizzo

they actually sell eccentric shafts with four journals?

Bigus Dickus

There are a couple of places or people that can make one for you.

Weight????

aZizzo

If you know these places, call em up and ask them what the weight of these motors are.

Kurgan

When I shipped my 3rotor to texas, with all of the manifolds and the stock twin turbos as well, it weighed in at 325 lbs dry. no oil or coolant. That's less Power Steering and AC.

You can build a reliable 600 hp 20B with a nice big turbo on it, and when you want brag, turn the boost up and crank out an 800 rwhp dyno sheet.

The dry sump oiling is something that I never looked into, but expect big money there... but if your budge for the engine alone is 50k, you will come WELL under that with a fully rebuilt, dry sump, single turbo 20B. I can't see it costing more than 20k, probably less... but I'm not sure.

I know a 350 SBC fits in a 2nd gen rx7, so does a 20b... I suppose I could go and measure my 20b for yeah... hang on.... (I have a fully built 20B on an engine hoist in the garage)

From the back of my pressure plate, to the very front of the front cover, it is just a hair over 26" (length)

From the outer most part of the lower intake manifold to the end of the spark plug sticking out of the other side, it is right at 17" (width) I did not include any exhaust manifold or turbos here, cuz that would obviously change from application to application.

I don't have my upper intake manifold on, but just eyeballing it, with a dry sump, from the top of the stock upper intake manifold to the bottom of the block, not including the oil pan, it would be right about 26" (height).

The rear bolt pattern is the same, or nearly the same as the 2nd gen engine. You can find the plates all over the place that are cracked, but will show you the bolt pattern that you need for the tranny adapter.

My engine was ported for torque, but will still flow enough for 800 bhp, with the right turbo. I'm going to go with a garret GT40/42 or something in that range... day to day, I'll run little to no boost (like 5-7 psi), but wil be able to crank it up to 20-25 psi for 650+ rwhp range.

Ultimas are badass, and I'd love to see a 3rotor running around somewhere. I'm glad you're considering the rotary for your project.

THe uniqueness of an Ultima, paired along with the obscurity of a 20B would make the perfect car... only problem is the tranny....

Also, if the engine height is too much, you can always go with the RE Amemiya special intake runers with individual Throttle Bodies That may put you around the 50k mark

Also, if you decide to go with a 3rotor, contact me and I'll hook you up with the cheapest place that I've found, as well as recommending some other things, such as the builder (Marvelspeed), fuel system... yadda yadda.

If you decide to go with a 3rotor, there is a 20B forum on this board. Several people in there can help you out as well.

Personally, I would shy away from a 4-rotor. A 3-rotor can give you killer power and little rate... but, a twin turbo 4 rotor would be badass! Through a couple of T-66s on it, Bwahahahahha! POWER!!!!!!!!!! (power = money)

Bigus Dickus

Much appreciated Kurgan.

The numbers you provided give me a good idea of what I'd be looking at as far as packaging and total vehicle weight.

Hmm... that would make a four rotor about 35" long or so....