Copped the bloody flu on the weekend and so i sat at home watching telly and thinking crazy sh!t for a couple days. one thought that refuses to die is replacing the trusty efi 2L (in the kombi) with a Renesis. has anyone done this? is it a feasible thing to do?
the Mazda RX8 weighs 1337kg and a kombi with a slightly heavier donk would be almost the same. the gear ratios of the 2 cars are similar, with 1st and 2nd almost the same. kombi's 4th is substantially lower than RX8 6th to allow for brick like aerodynamics.

i would be thinking of keeping the standard ecu to run all the nice things like S-DAIS (sequential dynamic air induction system)

below is a torque graph copied from: http://www.step-hen.com/rx8spec.htm  (i don't know where he got it from.)



and a graph of kombi 4-speed gear ratios (solid line) vs RX8 6-speed ratios (dashed line), produced with software downloaded from: http://www.geocities.com/MotorCity/Garage/1811/ 

Quote:

Originally posted by bus914 ...and a graph of kombi 4-speed gear ratios (solid line) vs RX8 6-speed ratios (dashed line), produced with software downloaded from: http://www.geocities.com/MotorCity/Garage/1811/

nice, but...

the RX8 13B is quite expensive and hard to find at the moment.

You would be better off going for an RX7 13B turbo. cheaper, easy to find, and more power. Potential for much much more power in the future.

I sold these when they were on the water

I'd be happy with a 20B n/a.....probably wouldn't need or use all the power, but the extra torque over the 13B n/a could be useful. Having said that, 220 odd Nm's from the 13B is still a decent improvement over current engine (albeit at higher revs) and roughly equivalent to a modern day 2.4 litre.

yer i agree with seagull mate, RX7 13b turbo and naturally aspirated engines are easy to find for parts, and complete engines, are S**TLOADS cheaper and have (at this point in time) more bolt on options for more power

i had a friend in year 12 who bought an unregistered RX7, bought a 13b turbo from the paper and licenced it and is still driving it three years on, engine goes very well, but when you drive it hard it uses more fuel than my mates 355ci VT commodore!!!

try MAZFIX in bris about RX8 renisis engines they generally have quite a
few as for 20B's too expensive. rotaries might not be everyones fave(I never liked them now I own 2!) but they are compact and fairly easy to fit

What i like about the graphs above is that i could drive it like i do the 2L, ie shifting at 20, 40, 60kph. Then i have another 4k rpms of fun in reserve in every gear. when the revs drop to 1626, on the first to second change i'd still have more torque than a stock type 4 at peak (about 101Nm).

anyone have a torque chart for a stock rx7 13b?

it'll be 18 months before i scrape up the funds in any case.

[ Edited on 7-7-2006 by bus914 ]

seagull has a VG30DET motor has ecu 200kw great torque easier to wire and cheap pretty compact as well.

i guess rotarys will go the way of the tazzie tiger if fuel prices continue current trends. for all the fancy electronics the Renesis still averages 12L/100km.

Malcolm, i wouldn't know what to do with 200kw

maybe it would be better to go 2.0FSI or TDI?

[ Edited on 12-7-2006 by bus914 ]

Have you seen the graph for the auto version of the rx8 13b?

Kombi Kountry, thats the grey line. labled as (RX-8 JPN standard power)

I love rotary engines, but I have to say, I'm with Wes. Seems like a lot of trouble for not a lot more return when there are more common and easier alternatives.

For Eg.
Holden V6 - cheap, very torquey, parts available everywhere.
Toyota V8 - the best modern V8 in production, cheap, plentiful, MEGA strong.
Subaru EJs - cheap, plentiful, done before, lot's of variety, torquey, what VW boxers should have been.
Mazda 13bT - cheap, plentiful, lot's of development available, big Hp potential.
Rover V8 - bargain basement kits still around 2nd hand, cheap, lots of hotup parts, old school.

The question you need to ask yourself is...

What are you gonna use the car for? towing/cruising/motorsport/drags
And,
What is your budget? $1k/$5k/$10k etc.

If you aim for nothing in particular, you will end up with a car that doesn't so anything well.

The V8s and V6 are good for towing and big big HP (particularly the toyota).
The Subies are great for cruising, limited motorsport and fuel economy.
The 13bT is excellent for big Hp for the drags or some motorsport.
The Rover can be very, very cheap fun.

I went a big cube NA subie in my buggy, coz I wanted the smoothness and the feel of a large capacity motor that wouldn't lunch gearboxes they way turbo motors do, coz my budget was limited. Think about what you want from the car before you do the conversion, then pick the donk that will deliver that.

Thanks for bringing this up Pete. i should have posted it first.

This is what I want from a conversion:

· Fuel economy (yeah the rotary is ordinary in this regard, even Renesis i realise)
· Drivability – Good overtaking power. Work exceptionally well with the stock gears. Easy to drive – good wide torque curve.
· Reversible – preferably no cutting around the engine bay etc. Minimal engineers’ certificate mods or better yet, none at all. (why? No one would have imagined that a good condition, bog stock splitty would be worth anything in 2006, 20 years ago)
· Quiet – no one wants to hear or feel the engine inside the cabin. Without extra noise insulation.

I’ll virtually never tow anything. It’ll be a round town and freeway family car. For motorsport I have a fasty.






[ Edited on 12-7-2006 by bus914 ]

vg30det cheap and bullet proof

Hate to say it but, an EJ22 is the ticket then. Virtually the same sorts of specs and feel as a big bore type 4, only much smoother and quieter, better fuel economy...and cheaper than the RX8 motor.

I'd put the renesis in a beelte, but I think for it's size and power output, it's wasted on a kombi.