Best N/A wankel to build cheap-ish and put in FC?

[MJG]

Hi all,

I currently do not own any Mazda, but reaaally have love for the RX\'s (hense me being here!). I will not have the funds/space for 2 cars for maybe a year at most, hopefully, but when I do I want to get an FC to tool about in on the roads with occasional track use. I am into drifting but already have a pretty sorted e28 BMW which is my main baby, but I want another car to use on the roads so would be keeping most of the interior and won\'t be taking it quite as far as my BMW to keep it "comfortable" whatever that word means.

Anyhoo, I should have space in my new house to do a bench build of an engine, and rather than making a BMW engine I figured it would be very useful to get a rotary engine to play with and rebuild how I want with the intention of then buying a car and putting my sweet engine into it. I used to raise my nose at the thought of an NA RX, but recently I\'ve really gotten into the idea of a revvy, kinda-gutless engine that sounds as sexual as a rotary, in a fairly lightweight and fun chassis.

I was wondering, after taking a quick look around ebay, what sort of engine you guys would recommend for a cheap as possible but still good rebuild? I don\'t want to completely throw economy to the wind but I understand whatever I do won\'t be frugle (my BMW is a 3.5 anyway!), I don\'t want to buy all sorts of fancy bits if I can help it since I\'m pretty poor, and I want it NA!

What engine codes should I be looking for, 12a, 13b whatever I\'m not really up on what I would benefit from getting, carb? EFI? Early? Late? Completely toast but free, or pay £50-100 and get one that isn\'t too far gone? Where\'s the best places for rebuild kits that I can fit myself etc?

Any advice/comments would be gratefully received, also, what sort of mods (preferably free or cheap!) could I do to improve torque and power between 4k - 9k or however high I could get it to rev? I want to be able to spin the wheels in 3rd round corners and have some tractability so don\'t want it to just have a million horses at a million rpm, I want some power from half way down the rev-range at least ideally.

If you could recommend some search terms that I could use then I will glady trawl through, but at the moment I\'m not really sure what even to be looking for!

Cheers!

Mike

[Grizzly]

Idealy you would be best of with an Early 13b NA engine from a very late First gen or a Very early second gen.

I say this becouse the later Second gen NA\'s had a 6 port setup and this would make things a bit more complicated, In a nut shell you could possably use T2 Secondry Plates to give a larger Inlet port with little Inlet manifold Changes.

But the thing is it all depends on what you want to do with it (Trackday car or roas etc) then how heavy will the car be (becouse rotarys don\'t usaly have alot of Torque) and how good are you at Engineering tasks? Becouse if the Car is fairly light and you are an Engineer or know one, you could build a simple NA P/P engine that would not need the std Inlet and could be run of Carbs.

[MJG]

Thanks for the reply.

I am an apprentice at Rolls-Royce, was trained basic engineering skills, and am doing a degree in manufacturing engineering, I am only working the the lab but they train us the same at the start. I have a keen engineering mind though so would like the task of making something.

I will do some searching about the P/P which I assume is peripheral port? I will search some about this then see what other questions I might have.

I am aware of them not having a lot of torque. I would like to get an FC, then strip off any unnecessary stuff like rear wiper/motor, under-carpet sound deadening, any silly heavy trim or electric mirrors, would remove sunroof etc but would rather not go too extreme unlike my BMW.

I hear that the FC is about 1300kgs, so without an A/C, or emissions bumf, and all the bits of trim removed that I could, no ABS if fitted, no luxuries basically, I would have hoped to get to around 1200kgs, although before I heard FC\'s were so heavy I would have aimed for 1000kgs.

At 1200kgs, I would be wanting about 140lbft minimum, but preferably more.

The car would see the track, but would be a drift car mainly. Welded diff, mods to increase steering lock if possible, and some nice stiff coilovers. Drifting commands a lot of power but I don\'t see the point and enjoy the task of drifting cars with not much power since it is much more rewarding. My first drift car was a 2.0 Sierra and rather than buying it back, I thought I\'d just go for something a bit different like an FC, and since I love them - it makes perfect sense!

[Grizzly]

If you keep it basic a P/P engine is not to hard to make and as its about as extream Port as you can get with the roght setting up etc you should easy see 250\'s but it has been known to yeald alot more Hp if you use the Right size Port and you get stuff like the fueling and Timing right.

As you say you need to do a Bit of reading up on peripheral\'s but if you are not going Turbo and want to make a Bit of a Track wepon its the way to go. (you may want to Try the Aus and US forums as P/P Is not something thats used alot over here)

Also may a Sugest you look at the First Gens for a Shell to put it in, there Lighter and cheaper to buy

[MJG]

never really been a fan of the first gens and would have thought they\'d be more expensive too? Ah I\'ll look into them too.

Cheers for the info on P/P, 250bhp!!! Holy crap that\'s loads! Hahaha if I got 250bhp in an FC then I would be happy. Will check out some aus forums yeah.

Thanks for advice

[MJG]

Hmm, just read into peripheral porting and I think despite the rediculous power to be had, and despite the fact I\'d love to have a car so savage it doesn\'t idle and you have to rev off the clock to pull off from the lights, I think I\'d probably get ass-raped for petrol and I\'d rather not do this to be honest! It seems that an extended or bridge ported motor might be a bit more suitable, and according to one site I just visited this is good for 200bhp? 200bhp would be plenty for me, as long as it had some kind of torque!

If the 0-60 would be below 7.5seconds, then perfect, I\'m not after a "fast" car, just something very fun to drive and useable every day when it hopefully won\'t be blown up

[Grizzly]

Depends how extreme you go, if you keep the port on the Small size it will Idle.

From what i\'ve read up on P/P\'s its like anything if you make a Masive Port it will Idle at 2k and develop all its power fro 7k but people forget that Mazda Started out with that style Ports on its Road cars in the begining.

If you want safe and Reliable you may be best looking at an Extended port but you have to remember if you are not Turboing it the Power will always be quite high up the rev range. Rotarys are a Bit like (dare i say it!!!!) V-tec\'s they don\'t do alot in NA form below a set rpm.

[MJG]

I don\'t mind high up power, I would like it to rev to 20k if possible, I don\'t mind working it. My BMW is fun because it has a million torques at 0rpm but would like something with no torque and screaming horsepower.

I thought about that small peripheral port theory, would a peripheral port of medium size (whatever that might be) be more efficient than a side port (or whatever it\'s called) of similar size? ie - would it use less fuel/harm the engine less/be more driveable, than an extended side port? Surely drawing the air/fuel in on the centre of the combustion chamber from a nice smooth intake port must make the engine happier than getting it from the crummy crushed up port in the sides (sorry not sure what you would call a "normal" port).

Thanks again for the info Grizzly, making me happy happy happy.

[Grizzly]

P/P or Side port??

It depends on Which side port you are compairing too, a Full Bridge and a P/P the Peripheral will run alot better (better Idle & better on Fuel) but if you are compiring a P/P to a std Extended port then apart from the Power diffrence the P/P will idle higher, drink more fuel etc

Don\'t forget though a P/P will always out flow a Side port of the same Volum becouse it delivers a More direct Flow (smoother and shorter Runner) the side port will always have a 90deg corner just before it enters the chamber slowing the Inlet charge down.

As anything it all depends on how far you want to go. The basic rule is the more Overlap the harder it is to Drive on the street and the lower the MPG.

I know what the next question is going to be... Overlap is when the Time the Inlet and Exhaust ports are open at the same time, the bigger the Port usaly the more the Overlap effect you get, You can tell how much overlap an engine has by the Brap Brap Brap noise it makes and the RPM it idles at.

[Grizzly]

This may be a daft sugestion but why don\'t you buy a Blown stock FD engine then rebuild it and buy an Fd with a Dead engine and fit it?? or if Moneys more of an Issue get a Turbo 2 engine and do the same.

I know an FD with little done to it will change your whole philosophy of a Fast car

[MJG]

Thanks for that, pretty much what I thought then. Anything stopping me making a comparitively small P/P which is just a more effecient version of an extended port? Getting rid of that pesky 90deg corner

I know what you meant by overlap, but cheers for clearing that up

As long as I can get 25mpg on a motorway? Or is even that being too hopeful?

By your last post are you recommending a turbo\'d engine? I don\'t want a fast car, just something quick enough and fun to drive I have pretty much no money so would be trying to do everything possible for free by mates/myself etc, turbo\'s are another expense I can do without for now.

[Grizzly]

I did quite alot of reading and asking people that are in the Know about peripheral\'s a cupple of years ago. I was/Am building a P/P Turbo (if i ever get round to Finishing it) and the idea was to make it as Drivable as Poss on the Road so my Ports are quite small (of the top of my head 25-30mm) and there very high up the Housing (about as close to the Top stud as you can get without Going through)

I am a bit into Turbo\'s but the guy who made my Housings ran a P/P as an Every day car and apart from the Dodgy MPG he said it was quite drivable.

[MJG]

How dodgy is the MPG, ballpark figure? And what is it you mean about it being high up the housing? Doesn\'t this have an affect on the timing, ie the same as making the valve timing more advanced?

[Grizzly]

I\'ll ask how bad his MPG is (I\'m not sure i was always more intrested in the Turbo  Side of things)

yes it makes the Timing open earlyer but more Importantly shut earlyer too, If its going to be Driven on the road for the Few Hp you loose you will gain a better manered car.

[MJG]

Ah right, I\'ll do some more research into this then. If you could get me an idea as to MPG and I can decide whether the screaming 250bhp is worth the heart attack or whether I should just tickle the ports and be happy with 160-170bhp and less death-inducing economy haha.