Rotary vs V8 economy run

[SHAKER]

I own a 5 litre Falcon with very modified internals ( major head work, forged pistons, big cam etc) I also recently purchased a stock 13B non turbo rx7 series 4 as an everyday driver. This may suprise a lot of you but driving very sedatley in the rx7 i reached an economy figure of 20 litres per 130 km, In my XA Falcon i could quite easily manage 200km with 20 litres of fuel driving very aggresively! The rx7 is an auto which wouldnt help the economy(id rather a manual), Would putting a manual box and extractors and better air filter greatly improve the economy of the rx7? I want to keep it for everyday use but with that kind of economy theres no way ill be able to afford to keep it, especially when im used to 5 litres for every 100km from my 1.5 pulsar, (which i was going to sell, but having second thoughts about it now)! Any rotary freaks out there that have any advise about getting better economy?

[fpv_gtho]

So thats basically about 15L/100km on the RX7 driven easily and 10L/100km in the Falcon driven hard. That seems quite conservative on the Falcon's side, i would have though a 30 year old, modified V8 wouldve struggled on economy runs, the injected V8 my dad has gets around 13L/100km at best, 16 whilst towing and when he starts pushing it it easily tops 20.

[SHAKER]

The falcon runs a 2.92 diff ratio which helps it economy wise. It may be a 30 year old model car, but its been completly rebuilt by hand and has won a trophy at a car show before i owned it!Its probarbly more economical than a stock 302 simply because of the fact it breathes better and has more efficient heads. So you think 15 litres to 100km is good for a rotor? I put injection cleaner in it today and i noticed when i started it when it was cold it started a lot quicker and didnt rev out as if it had a auto choke stuck on too high as it would previously, so hopefully that will make it run more effeciently.

[fpv_gtho]

well i wouldnt expect too much better than 15L/100km out of the RENESIS 13B but someone who had no knowledge of rotary engines or had never owned or driven one may still get disgusted by those figures. you may find youself putting injector cleaner into the engine alot more as you cant afford to leave rotaries unattended but if it does what you say it does than it might be worth the trouble

[Falcon500]

Dont forget rotaries need to be heated up like a peiceof agricultural equipment other wise they wont work very well....

[fpv_gtho]

well warming up a car might not be that much of a problem, i dont know if his XA would need it alot but my brothers old VK SS needed a good warm up every morning

[Falcon500]

Rotays NEED this warm up period to get their clearneces right...other wise you risk a fair bit of damage....most engines like to warm up before they go rotars really do need it haf the relability probelms with ratars are the drivers who dont look after them....and its a real pain because you cant be in any real hurry...

[fpv_gtho]

well according to Castrol, any car can have bad engine wear by not warming up properly. Definately one of the biggest things that kills rotaries is the owners thinking they'll live forever without needed a top up of oil or anything

[SHAKER]

Well quite not so suprisingly the XA has a windsor which are renown for running hot so it warms up in a matter of minutes( i never drive it on a hot day otherwise itll cook itself). Yes you do have to warm a rotary up and you cant start it then stop it straight away as theyll flood quite easy,and when they flood theyll be flooded forever unless you go thru an exstensive process to get rid of the fuel. Anyway i took it to a rotary sopecialist today and he said i should get a lot better economy out of it, hes servicing it and putting a new air control sensor and less restrictive filter,he said it was running way to lean aswell.Hopefully thatll cure it or else hell have to rip the injectors out and get them cleaned. He said he can import a 13b turbo engine and box in good nick and install it for around 5 grand, sounds pretty tempting, but id have to sell my falcon to do that and i dont want to sell the XA, its in too good a nick to sell it just for an engine..

[fpv_gtho]

what sort of fan/radiator setup are you running on the XA? my mums old XA Fairmont only overheated once with the 302 and that was because we went away for a weekend and the water mustve evaporated or something over the weekend but i think it also got a hole in it along the way....

[eyebrows]

one thing i saw a racing team do with a RX7 was run it very rich... they said it was for reliability, so with your RX7 the problem might very well be for it to running lean... ne way maybe some one knows why the rotary is so severely effected by the air mixture (y it effected more so than a conventional engine) can post why.

[SHAKER]

I have to wait till monday to get the car back now(rx7),Im hoping itll run smoother quicker and more economical otherwise im not gonna hang on to it, with the XB series Falcon, it would of been a cleveland, ive had 2 351 clevos, and one never ran hot and the other did run hot but the rad was blocked, after i got it cleaned out it ran sweet. My Xa hes done less then 10000 miles from a ground up rebuild from about 12 years ago and all the parts look brand new, i have a heavy duty fairlane 3 core rad, with shroud an engine fan, i should really get the rad cleaned, new water pump and wack some thermos on it, but i doubt the rad would be blocked cause its in such good condition, but you never know.

[Falcon500]

Originally Posted by eyebrows

one thing i saw a racing team do with a RX7 was run it very rich... they said it was for reliability, so with your RX7 the problem might very well be for it to running lean... ne way maybe some one knows why the rotary is so severely effected by the air mixture (y it effected more so than a conventional engine) can post why.

Ahhh the difrence is those engiens are working being pinned race engiens that dont stop in a race they get more power and its much safer then running it lean....lean is betteer for power but isnt really safe...most drag racer lean out their mixture for the power boost it gives...and they mostly can get away with it in the short bursts...

[SHAKER]

Well i get the rx7 back tomorow, the bloke whos doing the work on it seems pretty honest, but very expensive, he changed the airflow sensor and put a modified air filter on it, but the airflow sensor wasnt the prob, he then took the injectors out and they were all new, but he did noticed the rings around them were perished so he replaced those(I forget what theyre called). He then put it on the dyno and noticed the headers were getting hot really quick which indicates it might have a blockage in the exhaust,(possibly catalytic convertor).So he now has to fix that, hopefully itll be a different car when i get it back in terms of power and economy! A bloke from work has got a series 4 hes spent 30 grand on it, he claims its the most powerfull street registered rotary in Adelaide pulling 306 kwatts at the rear wheels. The cars been defected so he wants to sell in it parts, he wants 10 for the engine box diff, he reckons he pulled 10.3 down the 1/4 and got it off the clock on the freeway( the speedo in the series four go to 260 km/hr)Im very tempted to purchase it!

[fpv_gtho]

well just as long as hes honest, although you might feel the extra money may not be worth it if he charged way too much. theres this auto electrician who loves across the street from me that charges way too much and is probably dishonest as well so i guess you didnt get the worst rat in the hat.

if you did wan to purchase the car, its already been defected so unless you were going to address the illegalities of the car, it would only be good on the strip and track. if it does turn out to do what he says though it should be a hoot to drive