Alternative chassis using turbo'ed rotary power
12-30-06, 02:26 PM
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Alternative chassis using turbo'ed rotary power
I thought I can post it here. While it's not RX7 it still has some common things - rotary and single turbo setup.
It's a project that I'm working on for about 3 years now. Chassis is a semi monocoque with tubular steel front and rear subframes and integrated full FEA spec roll cage. Carbon fiber/Kevlar/ alu honeycomb monocoque similar to safety cell used in LMP racers and formula cars except it’s a two seater. Crushable impact absorbing structures front/sides/rear. Overall chassis layout is very similar to Koenigsegg’s.
Weight under 800kg. (For those who may be interested: Low weight = higher accelerations – forward, braking, cornering or any combination of those. Also safety – impact energy is directly related to mass (m) in old Newton’s equation. Unfortunately weight has nothing to do with top speed which is not result of torque/weight/traction ratio but power/drag ratio). While this project is a street car it was designed like race car in many ways. Two reasons – I’ve never designed a street car and I love the thinking that is normally behind any proper race car: “This thing has to outbrake, outcorner, outaccelerate and finally outlast the sh$$$t out of competition. This thing has to be strong and safe. Sooner or later it will be smashed into the wall HARD! The guy should simply unfasten his safety harness and walk away”. Also GT2/GT3 racing program was always kept in mind.
Extensive aerodynamics with underbody tunnels/diffusers. It generates moderate downforce ( ~350lb) in its street spec (no rear wing and front underbody diffuser) and center of pressure is very stable, located slightly rearwards of CG for enhanced high speed stability.
With suspension two versions where designed– one which is more traditional and another is F1 style inboard suspension. This second layout allows to convert a street car into race car within 20min. All you needed is a jack and two wrenches. By changing push rod on bell crank mounting point motion ratio is changed from 0.8 to 1.1 that will give 2.06 times higher wheel rates, same goes for sway bars – all in all it is about relocating 8 bolts. All that is left - turning down spring perches prescribed amount of turns to lower ride height…. I know that most people will consider it PIA anyway. But this could be a very nice option for those who will like to take it on a race track (Highly recommended as it’s the best place where one can enjoy its true performance).
Engine is turbocharged Renesis placed well within wheelbase. Still looking for which combination of parts will give me best compromise – fastest possible spool/350rwhp. GT3582R with 4 0.82 hot side probably…
Transmission has two options original RX8's GB/prop. Shaft/Diff combo and rear mounted transaxle connected to engine/clutch via torque tube as was made on 944, Farrari 550 and many others. Latter is more expensive but giving nicer weight distribution.
It’s definitely not a daily driver but a car which will look/feel great on the race track and parking lot of night club. It’s intended to compete with UK’s Noble.
Here’s some coupe and roadster pictures…
My intention is to ask for your rotary poisoned impressions/opinions. Also I’m not an engine guy by any means. I will probably hire a reputable rotary specialist to build prototype engine/turbo setup and do initial tuning but I want to learn/understand as much as possible to extent that I can have educated opinion on what that specialist is doing.
Is there anyone who wants to own one as next Christmas gift?
Cheers
Ted
It's a project that I'm working on for about 3 years now. Chassis is a semi monocoque with tubular steel front and rear subframes and integrated full FEA spec roll cage. Carbon fiber/Kevlar/ alu honeycomb monocoque similar to safety cell used in LMP racers and formula cars except it’s a two seater. Crushable impact absorbing structures front/sides/rear. Overall chassis layout is very similar to Koenigsegg’s.
Weight under 800kg. (For those who may be interested: Low weight = higher accelerations – forward, braking, cornering or any combination of those. Also safety – impact energy is directly related to mass (m) in old Newton’s equation. Unfortunately weight has nothing to do with top speed which is not result of torque/weight/traction ratio but power/drag ratio). While this project is a street car it was designed like race car in many ways. Two reasons – I’ve never designed a street car and I love the thinking that is normally behind any proper race car: “This thing has to outbrake, outcorner, outaccelerate and finally outlast the sh$$$t out of competition. This thing has to be strong and safe. Sooner or later it will be smashed into the wall HARD! The guy should simply unfasten his safety harness and walk away”. Also GT2/GT3 racing program was always kept in mind.
Extensive aerodynamics with underbody tunnels/diffusers. It generates moderate downforce ( ~350lb) in its street spec (no rear wing and front underbody diffuser) and center of pressure is very stable, located slightly rearwards of CG for enhanced high speed stability.
With suspension two versions where designed– one which is more traditional and another is F1 style inboard suspension. This second layout allows to convert a street car into race car within 20min. All you needed is a jack and two wrenches. By changing push rod on bell crank mounting point motion ratio is changed from 0.8 to 1.1 that will give 2.06 times higher wheel rates, same goes for sway bars – all in all it is about relocating 8 bolts. All that is left - turning down spring perches prescribed amount of turns to lower ride height…. I know that most people will consider it PIA anyway. But this could be a very nice option for those who will like to take it on a race track (Highly recommended as it’s the best place where one can enjoy its true performance).
Engine is turbocharged Renesis placed well within wheelbase. Still looking for which combination of parts will give me best compromise – fastest possible spool/350rwhp. GT3582R with 4 0.82 hot side probably…
Transmission has two options original RX8's GB/prop. Shaft/Diff combo and rear mounted transaxle connected to engine/clutch via torque tube as was made on 944, Farrari 550 and many others. Latter is more expensive but giving nicer weight distribution.
It’s definitely not a daily driver but a car which will look/feel great on the race track and parking lot of night club. It’s intended to compete with UK’s Noble.
Here’s some coupe and roadster pictures…
My intention is to ask for your rotary poisoned impressions/opinions. Also I’m not an engine guy by any means. I will probably hire a reputable rotary specialist to build prototype engine/turbo setup and do initial tuning but I want to learn/understand as much as possible to extent that I can have educated opinion on what that specialist is doing.
Is there anyone who wants to own one as next Christmas gift?
Cheers
Ted
Last edited by Tudor; 12-30-06 at 02:40 PM.
It's a beautiful design, especially the coupe.
12-31-06, 11:08 AM
#4
Looks like very nice project, have you started building it yet? A carbon monocoque is quite an undertaking.
Since you're already doing a lot of custom work, you might want to look at a few of the 'newer' custom rotary engines.
www.rotamax.net builds rotary engines that are very lightweight, but I'm not sure if they've been tested with forced induction yet.
I've also heard that Atkins Rotary will be manufacturing their own proprietary rotary engine for aircraft and marine use, again very light but it might not make 350rwhp.
Have you got much experience on the electrical side of things? It would be a shame to see a great mechanical project hampered by a first-time wiring job. I'd recommend using shielded wire to prevent interference from affecting the important sensors: crankshaft position (or rotary equivalent), throttle position, and manifold absolute pressure (MAP). Aircraft-quality wire is more expensive than the automotive-grade stuff, but it's much lighter and can withstand a lot more abuse. Some specs to look for are MIL-W-16878/6 or MIL-W-22759/18 . I'm not sure where you'll be able to purchase this from since you live in Russia, but I get mine from www.aircraftspruce.com or www.mouser.com
I'd love to see some photos of the suspension design, it sounds interesting.
-s-
Since you're already doing a lot of custom work, you might want to look at a few of the 'newer' custom rotary engines.
www.rotamax.net builds rotary engines that are very lightweight, but I'm not sure if they've been tested with forced induction yet.
I've also heard that Atkins Rotary will be manufacturing their own proprietary rotary engine for aircraft and marine use, again very light but it might not make 350rwhp.
Have you got much experience on the electrical side of things? It would be a shame to see a great mechanical project hampered by a first-time wiring job. I'd recommend using shielded wire to prevent interference from affecting the important sensors: crankshaft position (or rotary equivalent), throttle position, and manifold absolute pressure (MAP). Aircraft-quality wire is more expensive than the automotive-grade stuff, but it's much lighter and can withstand a lot more abuse. Some specs to look for are MIL-W-16878/6 or MIL-W-22759/18 . I'm not sure where you'll be able to purchase this from since you live in Russia, but I get mine from www.aircraftspruce.com or www.mouser.com
I'd love to see some photos of the suspension design, it sounds interesting.
-s-
01-01-07, 02:40 PM
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Scotty305, Thanks for kind words. Chassis tooling and assembly jig is done in UK by Paul Martin - more than 20 years in McLaren F1 being head of composite department. He designed and build all composite parts in all time great McLarenF1 road car.
Nothing in this car is made as first time attempt. Thanks a lot for the links - I knew aircraftspruce but never heard of mouser.com.
Gotbanned,
PM me if you're serious. First year production is only 20 cars most of which are going to UK and Japan.
Etihun,
Unfortunately even Mazda will still ruin the idea. They are experts of mass production vehicle business. All their major racing attempts where conducted by third party teams and outsourced engineering. Mass production means the product should appeal to so many different people starting from my Grand mama. Thing is this car is designed the way I like it. It's a race car but fairly streetable - like say Lotus Elise. Just much faster. It should accelerate well in all directions, not only forward. Cornering and braking is no less important. It should be fun and fairly easy to drive on the limit. Shouild be easy to catch and predictable past the limit.
It should also look and sound SEXY.
Cheers
Ted
Nothing in this car is made as first time attempt. Thanks a lot for the links - I knew aircraftspruce but never heard of mouser.com.
Gotbanned,
PM me if you're serious. First year production is only 20 cars most of which are going to UK and Japan.
Etihun,
Unfortunately even Mazda will still ruin the idea. They are experts of mass production vehicle business. All their major racing attempts where conducted by third party teams and outsourced engineering. Mass production means the product should appeal to so many different people starting from my Grand mama
. Thing is this car is designed the way I like it. It's a race car but fairly streetable - like say Lotus Elise. Just much faster. It should accelerate well in all directions, not only forward. Cornering and braking is no less important. It should be fun and fairly easy to drive on the limit. Shouild be easy to catch and predictable past the limit. It should also look and sound SEXY.
Cheers
Ted
Last edited by Tudor; 01-01-07 at 03:04 PM.
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01-01-07, 05:41 PM
#8
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Are you freakin kidding me!?? That car is one of the sexiest cars i've ever seen!!! What's the projected price on something like that? I might have to put off buying my new sand rail and toy hauler for a while 
Great job! Can't wait to see and hear more about it.
Great job! Can't wait to see and hear more about it.
01-11-07, 09:06 PM
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I love rx-7's
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you are a smart man to be undertaking this endever keep it up! I turst Paul Martin with all my heart, he is an exceptionaly good enginear/builder so you cant go rong. ps that car is going to look and sound sexy. i cant spell eather so sorry
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