YB cosworth powered Mazda Mx5...
19-01-2011, 06:58 PM
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YB cosworth powered Mazda Mx5...
Hi all!
This is my first post so let me introduce myself. I'm Nico, I live in Ludlow (Shropshire) and I bought last summer a YB powered Mx5 as a trackcar. It's basically a sapphire cosworth 2wd powertrain dropped into an early mx5. (engine+gearbox+diff)
The engine is stock (with 4wd turbo manifold and intercooler) but running an unknown stage1 chip. It's good fun to drive as the mx5 is light and has a good chassis (fully adjustable geometry). All it needed is a bit more power to make it really awesome.
I had to do a bit of work on the car to get it road legal. Then I did a trackday at the end of last year and a drift day at santa pod a couple of weeks ago.
Unfortunately at the end of that day the engine died and would not restart. It had developed a worrying tappet noise so I didn't run the car in the afternoon. The engine died while driving gently leaving the place.
I left the car at a garage and they've found that it was a broken exhaust camshaft
Has it ever happened to anyone here ? (I did a search and haven't found anything...) If yes, what was the cause and consequence ?
I have done lots of reading on this forum in the past few months but I still don't know too much about the cosworth engine....
This is my first post so let me introduce myself. I'm Nico, I live in Ludlow (Shropshire) and I bought last summer a YB powered Mx5 as a trackcar. It's basically a sapphire cosworth 2wd powertrain dropped into an early mx5. (engine+gearbox+diff)
The engine is stock (with 4wd turbo manifold and intercooler) but running an unknown stage1 chip. It's good fun to drive as the mx5 is light and has a good chassis (fully adjustable geometry). All it needed is a bit more power to make it really awesome.
I had to do a bit of work on the car to get it road legal. Then I did a trackday at the end of last year and a drift day at santa pod a couple of weeks ago.
Unfortunately at the end of that day the engine died and would not restart. It had developed a worrying tappet noise so I didn't run the car in the afternoon. The engine died while driving gently leaving the place.
I left the car at a garage and they've found that it was a broken exhaust camshaft
Has it ever happened to anyone here ? (I did a search and haven't found anything...) If yes, what was the cause and consequence ?
I have done lots of reading on this forum in the past few months but I still don't know too much about the cosworth engine....
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19-01-2011, 07:29 PM
#10
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i broke an exhaust cam in my last 2wd cossie racing my mate in his pulsar gtir, the cause was the last 4 cam cap studs had started to work there was out. so had to get them helicoiled new cam fitted and job sorted good as new.
20-01-2011, 09:03 PM
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! loose cam belt? slips a tooth piston slaps the valve causing it to stop for a fraction and snaps the cam shaft! esp when hi reving, or caining the nuts out it 
cam has no chance but to snap
my guess!
cam has no chance but to snapmy guess!
20-01-2011, 09:11 PM
#16
i snapped a ex cam , whilst taking pete mcrash's car for a spin lol ,
exact same place as where dickos did
same issue , studs worked loose ,
we simply re helicoled the studs , replaced the broken cam cap and put my cam in
still giving it death on a daily basis !!!
beef
exact same place as where dickos did
same issue , studs worked loose ,
we simply re helicoled the studs , replaced the broken cam cap and put my cam in
still giving it death on a daily basis !!!
beef
22-01-2011, 04:07 PM
#22
neeko ,
we didnt strip the head off the car , but if you go on the assumption , that when the cam snaps , the the lobes shift and the valve springs pull the valves shut then there shouldnt be any valve damage ,
i had to coast it bk to the gagage arouns 700 yards and it was running badly but still running ,
my advice would be to swap out the camshaft re time the engine and rotate it by hand to see if you have any issues , pay close attention to the valves where the snapped section was to see if theres any resistance ,
if not , id just fire it up
we literally helicoiled the studs , put it in ,and fired her up
as said still going strong
if i rember rightly you can use an inlet cam to replace an exhaust ( but not the other way round )
if thats tha case mate ive a spare one her you could have for cost of postage and a beer token or two ?
maybe worth asking in the genral discussion , but if im correct , drop me a pm
soon have it blatting about track
we didnt strip the head off the car , but if you go on the assumption , that when the cam snaps , the the lobes shift and the valve springs pull the valves shut then there shouldnt be any valve damage ,
i had to coast it bk to the gagage arouns 700 yards and it was running badly but still running ,
my advice would be to swap out the camshaft re time the engine and rotate it by hand to see if you have any issues , pay close attention to the valves where the snapped section was to see if theres any resistance ,
if not , id just fire it up
we literally helicoiled the studs , put it in ,and fired her up
as said still going strong
if i rember rightly you can use an inlet cam to replace an exhaust ( but not the other way round )
if thats tha case mate ive a spare one her you could have for cost of postage and a beer token or two ?
maybe worth asking in the genral discussion , but if im correct , drop me a pm
soon have it blatting about track
22-01-2011, 04:48 PM
#23
Zee Germans are coming
24-01-2011, 12:37 PM
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Beefy,
Thank you very much for the explanation and the offer
By the sound of it yours was still running on 3 cylinders (well... 2 and a half looking at your pictures). Mine would not fire up at all so I guess the shaft snapped closer to the pulley... I can't go have a look as unfortunately the garage I left the car at is quite far from where I live...
I'll ask them to change the shaft and see how it goes.
I'll post up the question about swapping inlet/exhaust cam in the main section.
Many thanks,
Nico
Thank you very much for the explanation and the offer
By the sound of it yours was still running on 3 cylinders (well... 2 and a half looking at your pictures). Mine would not fire up at all so I guess the shaft snapped closer to the pulley... I can't go have a look as unfortunately the garage I left the car at is quite far from where I live...
I'll ask them to change the shaft and see how it goes.
I'll post up the question about swapping inlet/exhaust cam in the main section.
Many thanks,
Nico
24-01-2011, 01:07 PM
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Nice car, i was going to turbo the std mazda engine in one once, lots of yanks are into it big style, wonder why the diff was changed the mazda diff is probably just as strong? maybe no lsd option? are the shafts and prop cut and welded? hope you get it fixed soon
25-01-2011, 08:27 AM
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Nope mazda diff wouldn't have cope with the power well not the one that came in this car.
will be nice to see this back on track shame you cant make brands. Bedford again ?
will be nice to see this back on track shame you cant make brands. Bedford again ?
25-01-2011, 08:48 AM
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Hey Ollie! 
Are you on EVERY car forum in the uk ?? ahaha
Yep I'll most probably be at Bedford again in march and I'd also like to do Cadwell Park the month after.
I think the main problem with the stock mazda diff is the way it's mounted. On the side it's fixed via bushings on the rear subframe, but on the front it's bolted to a long beam that goes to the gear box (so called PPF). Mx5s with engine swaps have that PPF removed and lots of people who have tried to fix the front of the diff to the rear subframe ended up quite quickly with a broken casing....
Are you on EVERY car forum in the uk ?? ahaha
Yep I'll most probably be at Bedford again in march and I'd also like to do Cadwell Park the month after.
I think the main problem with the stock mazda diff is the way it's mounted. On the side it's fixed via bushings on the rear subframe, but on the front it's bolted to a long beam that goes to the gear box (so called PPF). Mx5s with engine swaps have that PPF removed and lots of people who have tried to fix the front of the diff to the rear subframe ended up quite quickly with a broken casing....
25-01-2011, 09:24 AM
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Hey Ollie!
Are you on EVERY car forum in the uk ?? ahaha
Yep I'll most probably be at Bedford again in march and I'd also like to do Cadwell Park the month after.
I think the main problem with the stock mazda diff is the way it's mounted. On the side it's fixed via bushings on the rear subframe, but on the front it's bolted to a long beam that goes to the gear box (so called PPF). Mx5s with engine swaps have that PPF removed and lots of people who have tried to fix the front of the diff to the rear subframe ended up quite quickly with a broken casing....
Are you on EVERY car forum in the uk ?? ahaha
Yep I'll most probably be at Bedford again in march and I'd also like to do Cadwell Park the month after.
I think the main problem with the stock mazda diff is the way it's mounted. On the side it's fixed via bushings on the rear subframe, but on the front it's bolted to a long beam that goes to the gear box (so called PPF). Mx5s with engine swaps have that PPF removed and lots of people who have tried to fix the front of the diff to the rear subframe ended up quite quickly with a broken casing....
26-01-2011, 05:27 PM
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Beefy, you've got a pm
Yes it's pretty much removable like that:
Wheelbase is 2270mm
And yes, that's a really good base for a kitcar!
A company is selling a kit that you can build quickly and cheaply. It's basically a new lightweight body. (keeping the entire front and rear subframe)
Slight problem.... it's super fugly
http://www.mevltd.co.uk/
Thing to notice also is that unlike the Lotus Elan, the central "beam" is non-structural (not linked to the front and rear subframes).
Yes it's pretty much removable like that:
Wheelbase is 2270mm
And yes, that's a really good base for a kitcar!
A company is selling a kit that you can build quickly and cheaply. It's basically a new lightweight body. (keeping the entire front and rear subframe)
Slight problem.... it's super fugly
http://www.mevltd.co.uk/
Thing to notice also is that unlike the Lotus Elan, the central "beam" is non-structural (not linked to the front and rear subframes).
Last edited by Neeko; 26-01-2011 at 05:29 PM.
26-01-2011, 08:49 PM
#38
good project buddy 
my engine also failed in may last year and only when rebuilding my engine at the end of last year did we find i had snapped my exhaust cam, on cylinder 4 as well like Dicko&Sarah! unsure what caused it either!
my engine also failed in may last year and only when rebuilding my engine at the end of last year did we find i had snapped my exhaust cam, on cylinder 4 as well like Dicko&Sarah! unsure what caused it either!
Last edited by onslack; 26-01-2011 at 08:50 PM.
16-02-2013, 12:33 PM
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Hi all!
I have replaced the exhaust camshaft soon after my last post and the engine has run fine every since. Thanks a lot for your help.
Unfortunately I have used the car very little in the past 2 years
(new job...)
So now it's up for sale.
I haven't posted enough on here to be able to post in the "for sale" section so here is a link to my pistonheads add.
http://www.pistonheads.com/classifie...bo-mx5/1016940
Cheers!
I have replaced the exhaust camshaft soon after my last post and the engine has run fine every since. Thanks a lot for your help.
Unfortunately I have used the car very little in the past 2 years
(new job...)So now it's up for sale.
I haven't posted enough on here to be able to post in the "for sale" section so here is a link to my pistonheads add.
http://www.pistonheads.com/classifie...bo-mx5/1016940
Cheers!