Mazda mx5 engine or zetec

[angusgrooby]

Hi I have decided to change my engine in my swb roadster the old o series engine has had it so have decided to take the plunge ?! Looking at old treads other people have had the same thinking as me, getting a mx5 car and taking out what is needed ,price wise it looks like it may be cheaper than a zetec but there may be issues with the steering?
Has any one actually fitted the mx5 in roadster? in a previous thread some one was going to fit one and then veered of and fited a zetec instead was there a reason for this?
I understand that there is a lot of work and money involved with changing the engine and there will be problems which occur with both engine choices.
Look forward to your replies

[CosworthCabrioLee]

Re: Mazda mx5 engine or zetec

The zetec option is expensive time you get the water rail alternator brackets etc etc then You need to decide carbs or injection. The mx5 route is cheaPer as you can Pick a car up on eBay break it get your bits and then sell off what you don't need ie seats trim body etc

[angusgrooby]

Re: Mazda mx5 engine or zetec

Hi Lee the mx5 route really makes sense to me I carnt understand why there are not more kit cars with this engine. Hence the reason for asking the question do you know of any one in the club who has converted to the mx5 lump?

[stevejgreen]

Re: Mazda mx5 engine or zetec

Its an idea I have thought of. One issue thT would need to be addressed is the ECU. The same if you put in a Zetec but the conversion is much more common. It controls the complete ignition system from fuel to ignition and emissions. There are work arounds like a Megasquirt replacement that may be appropriate.
I agree though it seems odd that they dont appear more often etc.

[CosworthCabrioLee]

Re: Mazda mx5 engine or zetec

Westfield use the mx5 engine option quiet a lot might be worth checking there forums out, to my mind have not seen this conversion before so you may well be the first. Possible pitstop article

[dogoncrazy]

Re: Mazda mx5 engine or zetec

I'm not sure that the MX 5 would fit [I suspect issues with the intake and the Marlin steering] Having said that Lee was told that a Lotus twin cam wouldn't go in and we know that he proved them wrong. Worth considering is the Rover 'K' series onto a Ford 5 speed - that has been put into a Roadster. And wasn't there a guy in Holland also putting a Volks/Audi unit into a Roadster?

[lil_red_roadster]

Re: Mazda mx5 engine or zetec

It all depends on your budget and appetite for varying degrees of customisation/fabrication...
Complete new Zetec's can be had for c£750 but you have the cost of an ECU plus the necessary parts to convert to RWD (Burton Power have all the gubbins) plus a gearbox and exhaust. I also think it fits without the need to alter the column.
I'm sure an MX5 engine/gearbox combo could be made to fit & would probably run OK on the stock ECU...another option is an ex-Omega 2.0 Ecotec..? Comes in RWD form & a donor car can be picked up cheaply. K series will also fit nicely...
There's also a 2.0 Injected O Series on eBay at present...
Whatever you do don't underestimate the cost, complexity & time it will take..!

[cameronfurnival]

Re: Mazda mx5 engine or zetec

DOnt forget most engines have their problems - the mx5 rattles its brains out on startup whilst the tappets fill and can use a fair bit of oil.
I think the biggest problem will be the height of whichever engine you pick. Jez's (lil red roadster) is testament to the ingenuity of members and he has managed to get a Rover T16 in his - without vaseline or a mallet! Whatever route you take we will all be watching and able to help where we can.

[CABRIOBOB]

Re: Mazda mx5 engine or zetec

Which ever engine you replace the o-series with, I would recommend you keep records and invoices of what and when you purchased as when you come to advise DVLA of the engine swop they need to know all the facts, as I have done several engine swops in the past year and DVLA declined one of the swops on the first application untill evidence invoice of the purchased replacement engine and fitment was adviced.

[jon_cox]

Re: Mazda mx5 engine or zetec

OK Guys. Bare with me here. I have gone from a 1.3 A series to a 1.8 Fiat Twin Cam tuned with twin IDF's but I hate standing still. I have considered the MX5 and it will fit with a mod to the column. The 1.6 is slightly smaller than the 1.8. Be careful if considering the 1.6 as it came in 3 different power outputs. My latest thought however is POWER. So...... Volvo T5 has 240 BHP standard with much more with a bit of tweaking. Find a car that the police used and it will have 300 - 320 BHP. The engine is a 5 cylinder but relatively small. It will mate straight to an M90 RWD gearbox from the 960 with a slight mod to the sump to convert from FWD to RWD. These engines and gearboxes are ten a penny. I know there would be be a turbo and all associated gubbins to consider but if what you want is cheap and reliable power then.........?????!!!
Take a look at this for more detail. http://cgi.ebay.co.uk/Volvo-T5-RWD-E...#ht_956wt_1185

Thought gentlemen??!!

[lil_red_roadster]

Re: Mazda mx5 engine or zetec

Well it nicely covers power requirements..!
Seriously though a 5-pot is going to be a real squeeze in a Marina-Roadster...and with modern multi-valve engines the height can be the killer dimension...iirc the height of my T series from sump to top of the cam cover is c 57cm...with a bit more for the plenum; and that gives marginal clearance at the front between bonnet & lump.
Not to mention the need to seriously upgrade the entire vehicle to safely harness the power on tap. For anything more than a 4-pot swap I'd suggest a Triumph-based chassis would be better, and potentially offer some advantages at the rear (swap in a Stag/Ford diff?) and the front (more room fore-aft due to different rack; easier to tune spring rates; readily available brake upgrades).
Be nice to see it done though..!

[stevejgreen]

Re: Mazda mx5 engine or zetec

Jez has some good points if you are heading for 240+ HP in an 800Kg car. Certainly well beyond a Marina differential and standard leaf spring suspension.
The Turbo option sound interesting but where would you fit an intercooler?

It sounds an interesting and deserves its own thread when it gets onto the drawing board.

[lil_red_roadster]

Re: Mazda mx5 engine or zetec

Yes, intercoolers are a bit bulky...there's room under whichever wing doesn't have the silencer under it, or under the front apron (if not already full of oil-cooler)...or even sink them into the wings aft of the front wheels, and that way they help ease the under-wing air pressure..! If money is no object then the radiator/oil cooler can be combined in a custom unit to help save some space (or maybe a combined radiator & charge-cooler instead). PPC successfully demonstrated fitting a turbo at the rear of the exhaust system a couple of years ago...to remove heat from the under-bonnet area (and free-up some space). And then there's the idea of using the chassis box sections themselves as part of any ducting...perhaps permitting an intercooler hung out the back...

[jon_cox]

Re: Mazda mx5 engine or zetec

OK. I see the problem. So..... plan B. Honda S2000 is normally aspirated, is already RWD, has a 6 speed gearbox, revs to 9000 rpm, comes with 240 bhp out of the box and has the intake on the passenger side (no need to modify the column). They are getting cheaper.

[lil_red_roadster]

Re: Mazda mx5 engine or zetec

Good Plan B...VTEC in a Sprite...improved braking very much a "must have"...
VTEC-Sprite-C.jpg