starapex

I live in the area of Vancouver B.C. Canada.

I am looking for a !st Gen RX-7 with a tired engine. preferably running.

The plan is to modify the engine to obtain 25% better gas milage than when it was new and to increase the power by 33%.

Thanks

1stgen4life

iTrader: (1)

Can I ask how you suggest to do this?

GavinJuice

Yes, please do tell how you plan to "modify" this tired engine to reach those percentages.

starapex

The designers of the Wankel engine worldwide have not taken the time to understand some obvious principles that should make it superior to every IC engine in use today.

We have 4 first Generation RX-7 engine parts in our shop. The exhaust can be modified to meet the following principles.

THE WORKING CYCLES OF THE PERFECTED WANKEL ROTARY ENGINE

For proper functioning the intake port must be peripheral and located between the 6 :30 to the 7:30 o’clock housing position. The exhaust port must be peripheral and located just at or past the 6 o’clock housing position.

With the sparkplug surface of the housing facing up.
The starting point has eccentric shaft lobe (crank shaft throw) at the 12 o’clock position
The A surface of the rotor is facing up with its trailing apex seal in the 10 o’clock and the leading apex seal at the 2 o’clock position.
The C surface of the rotor is facing the 4 o’clock position with its trailing apex seal in the 2 o’clock and the leading apex seal at the 6 o’clock position.
The B surface of the rotor is facing the 8 o’clock position with its trailing apex seal at the 6 o’clock and the leading apex seal at the 10 o’clock position.

(1)When the eccentric shaft lobe rotates from the 12 o’clock to the 3 o’clock position the A surface completes its first third of its power stroke. The rotor apexes move to the 11, 3 and 7 o’clock position
At the same time the C surface completes its 2nd third of the exhaust stroke.
At the same time the B surface completes its last third of the intake stroke.

(2) When the eccentric shaft lobe rotates from the 3 o’clock to the 6 o’clock position the A surface completes its 2nd third of its power stroke. The rotor apexes move to the 12, 4 and 8 o’clock position
At the same time the C surface completes its last third of the exhaust stroke.
At the same time the B surface completes its first third of the compression stroke.

(3) When the eccentric shaft lobe rotates from the 6 o’clock to the 9 o’clock position the A surface completes its last third of its power stroke. The rotor apexes move to the 1, 5 and 9 o’clock position
At the same time the C surface completes its first third of the intake stroke.
At the same time the B surface completes its 2nd third of the compression stroke.

(4) When the eccentric shaft lobe rotates from the 9 o’clock to the 12 o’clock position the A surface completes its first third of its exhaust stroke. (The location of the port makes this stroke a continuation of the power stroke with the compression of the exhaust assisting the compression stroke. The rotor apexes move to the 2, 6 and 10 o’clock position
At the same time the C surface completes its 2nd third of the intake stroke.
At the same time the B surface completes its last third of the compression stroke.
The B surface will go through the same cycles mentioned before until the C surface completes its last third of the compression stroke. Then the C surface will go through the same cycles until the A surface completes it’s last third of the compression stroke and the circle of events is then repeated.

Take some time to study the process and you may come to believe that my predictions may be modest.

The engine completes three power strokes in three shaft revolutions and one rotor revolution therefore it completes three four stroke cycles or the total of twelve cycles.

Three surfaces work at the same time therefore three strokes take place in 3/4 of a shaft revolution. Six strokes take place in 1 1/2 shaft revolutions and twelve strokes take place in three shaft revolutions.

How is that for a start?

Directfreak

iTrader: (2)

Long-Winded..

Mazda already made vast improvements to the rotary. It's called side-exhaust ports.

Look at the Renesis 13B in an RX-8.

starapex

Mazda does not see what I explained in the last post.

A properly modified 1st generation RX-7 engine will be superior in both power, fuel consumption and longivity

Cheers Ken McKenzie

natew

iTrader: (1)

so you managed to explain how a rotary works...

Im lazy and dont wanna think... so how bout explainin your wonderful plan in plain english, step by step.

starapex

Print out my explanation and then confirm it using cut out mazda parts or actual engine parts. the ecentric shaft and the rotor positions are fully explained.

If it was simple Wankel, NSU, Mazda, Curtis Wright and Suzuki etc. would have incorporated the principles.

Your study will confirm that each rotor will have a continuous power stroke for a 360 degree eccentric shaft revolution. Mazda only has a power stroke for slightly less than half of that.

Cheers

Ken McKenzie

jimtesla

I need a visual of what your are tring to do.........

its seems that you want spark and exhaust on both sides......are you going to re-do rotor housings?

Is this project just for yourself or do you plan on a retro fit kit for all.......

What numbers will this engine achieve? Will it be cost effective?

I plan on looking into a retro kit to convert to Hydrogen power.......Thus my 7 will be smog exempt.......

starapex

The basic configuration of the engine is the same.
The location of the exhaust port has to be moved to the 6 o'clock position and the existing port closed.

Normal thought with engines is the spark plug is to the top and non rotary people would get confused if I tried to explain the engine with the spark plugs to the side.

Instead of releasing internal pressure while another surface is in or about to begin its compression stroke you hold the internal pressures until the compression stroke is complete.

The work involved is drilling another exhaust port from the same flange. making it water tight and having a plug made to insert into the original exhaust port. all else remains the same. The sparkplug and intake ports cvould be improved but that is minor in the scheme of things. perhaps look at my site at starapex dot com.

Cheers
Ken McKenzie

Metallic_rock

I think this needs to be moved to the tech section where there are people that can comprehend this. I can't.


I've got a nice little 1st gen with a 13b and a Sterling carb you can purchase from me... PM me. I'm in Spokane, WA.

Keaponlaffen

This belongs in the tech section, as it applies to the 12A or 13B engine in general....

either that or the "FOR SALE" Section where MOST people post want to buy ads

Sounds interesting though... I wish you luck if you attempt it. Let us know how it turns out.

QuagmireMan

dont you think that having the intake and exhauste port soo close together that will cause problems with warping or possible preignition?

dirty86

9000 usd for mine

starapex

The exhaust will not be as hot. The inertia of both flows will seperate them. The whole of the engine will have a more uniform temperature. The apex seals will always be held in place by compression, power and exhaust stroke pressures.

I will start a thread in the tech section shortly when I find it.

Cheers
Ken McKenzie

enigma32

Interesting thoughts, but frankly your presentation is rather messy. I'll be curious to see if you can make this work like you want to.

1984special

Hmmmmm, I don't get it. But still, I wish you best of luck. And I'll point you to tech...

https://www.rx7club.com/forum/forumd...?s=&forumid=11

Lotus00

I just glanced at your website, forgive me if im missing something.

with the intake and exhaust ports both open at the same time, wouldnt you get a lot of exhaust flowing out the intake? I could see maybe if you used some kind of forced induction, but I doubt even that would be enough to keep the exhaust flowing out the correct port.

what RPM would an engine like this idle at? I always thought that overlap in exhaust and intake cycles ment rough idle (whay a p-port idles so high).

guys, if you go to his site , its not too hard to figure out what hes talking about.

81Rex6port13b

hmmmm.... interesting. but..... if you rotated it 90CW it would look like this:




now isnt that very similar to how it is now? intake on top, exhast on the bottem? this there just closer together.

also the way he has it isnt it a little difficult to get good air frow to the intake? its on the bottem air will have to go up instead of sucking down

starapex

Actually the exhaust port should start just past the minor axis so we have continual pressure pressing against the compression stroke. (It is explained in a post at the tech section) What we have is a continual power stroke for 3/4 of the eccentric shaft revolution.
This is compated to 3/8 of a revolution that now takes place in the Mazda Rotary. There is no power produced 7 minutes before the eccentric shaft's lobe is at top dead center and the same for the first seven minutes after TDC as the lobe follows the rotor surface at that time.

People not farmiliar with the rotary engine expect to see the spark plugs on the top.

Cheers

Ken

jayroc

Look. My personal opinion here is that you're completely off your rocker. You talk like Mazda has overlooked some glaring technical flaw and you can somehow revolutionize the rotary engine. All achieved somehow by looking at 60 year old drawings and drawing crude pictures? And by doing this you have achieved some understanding that outweighs 30+ years of Mazda's R&D?
Maybe I'm wrong here, but you sound like someone who has no experience designing or machining anything. Then again maybe you're some mad genius. Either way, before you come on here making these claims, build an engine and show me some results, or at least some CAD drawings and how you plan on maching these parts before you start calling mazda's R&D a great big goof, as your website claims.

You mean.. like an oil cooler? Like every rotary engine has? It takes a certain amount of oil to propagate heat effectively in a rotary. If they removed the oil pan, the amount of oil available for cooling is greatly reduced and thus cooling ability is greatly negated. The bearings and e-shaft would heat up to intolerable temperatures, leading to inevitable premature engine failure.

This can also be a beneficial characteristic. It was addressed in the intake design of the FC's 13b in 1986. It's called dynamic or intertial supercharging.
The REAL problem is intake and exhaust overlap, which is improved upon by the new Renesis design.

Anyways, I really think you should be studying modern rotary engine design instead of the original prototypes, if you're thinking about doing any improvements...

Directfreak

iTrader: (2)

Well Said!!!!

Lotus00

ok, the only way I could see this engine idling is if it had valves of some sort so only one of the ports are open at any given time. the only problem with this is that there would be almost no time for the air to flow into the combustion chamber before the apex seal moved past the port.

maybe if you moved the intake port so it opens later, then you would still get a longer power stoke, but the intake would still be open during the begining of the comperssion stage, forcing some intake gas back out. (one of the things you wanted to fix).

what you are doing is just like a p-port, with huge ports. sure it makes a bitchload of power, but it doesnt idle worth a damn.

this is pretty intersting, though. i think it would be sweet if you built one and it ran good, but like the others said: I doubt that after 30 years of R&D mazda could have missed something as simple as port timing. (they did a lot of research on this, some of thier race cars were p-ports)

starapex

Take the time to study the engine components in their various positions and realize that 1/3 of the power stroke displacement is not used to produce torque.

Note the high exhaust temperatures that are the result of the early release of the high combustion that is required because of inefficient use of the displacement.



Wankel did not design the configuration known as the Wankel engine, and if you look closely at his first NSU prototype you will see that his sealing system left much to be developed after Feb 1 of 1957.

Mazda's modern thinking has side exhaust and side ports to show that they have never taken the time to study how the engine actually works

Please be assured that I can and will modify a first generation RX-7 to display incompetence in rotary engine design.

(maybe if you moved the intake port so it opens later, then you would still get a longer power stoke, but the intake would still be open during the beginning of the compression stage, forcing some intake gas back out. (one of the things you wanted to fix).

Mazda is already doing this It has the intake port open during the first third of the compression stroke.

The intake stroke port must be moved so it opens and closes earlier in a position just past the minor axis.

Cheers
Ken McKenzie

Lotus00

my question is will the rotary engine in you are proposing idle? I always thought that overlap in the intake and exhaust cycles was bad for idleing. You are suggesting almost 100% (or as close as you can get to it) overlap. Maybe im not seeing the whole picture, please correct me if im wrong, but you may as well try and use one port for intake and exhaust! You have yet to answer me, I have asked twice before, how is it going to idle? how are you keeping exhaust from exiting through the intake port?

I really doubt that mazda (or any) car manufacturer would produce an engine that they didnt know how it worked.

hey, my rotary isnt incompentent

In any case, build the engine. It would be cool if it worked, but I really dont think it will be able to idle at a reasonable RPM.