YB Cosworth engine MX5 road legal track weapon. T5 box, 7.5in diff, rear cage
13-10-2013, 02:36 PM
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YB Cosworth engine MX5 road legal track weapon. T5 box, 7.5in diff, rear cage
I Love this car, spent a lot of time making it awesome, and REALLY don't wanna sell it, but with one of my other cars getting so close to being done I've no choice but to put this up for sale to help pay for it.
PRICE-£4000ono
This mad thing...
Originally converted by Roddisons Motorsport (MX5 Racing - Roddisons Motorsport) a long long time ago (10yrs+?), the car has been a dedicated track car (not even road legal) for most of its life, but the previous owner re-made it road legal and drove it to Europe for track days. Because of it never actually really being a road car until I bought it in March this year, it's done very little miles, though exactly how many, I've no idea, but what it does mean, is rust wise, it's in damn good condition as it's never seen winter salty roads etc.
The conversion makes a lot of sense, especially compared to all these SR20 conversions people dream about etc, as the sump etc etc is in the correct place, so it all fits nicely with little to no mods.
As well as being fitted with one of the best, strongest, and most tunable 2ltr engines ever made, the Ford YB Cosworth, it's got one of the strongest RWD boxes too, the Cosworth spec Borg Warner T5, and a mega strong diff too, a 7.5" 2wd Cosworth one- Basically, unlike most MX5s, this one has a bulletproof engine and transmission.
You have no worries about the diff mounts or subframe breaking either, as it's all hugely modified/strengthened and solidly mounted too.
When I bought the car it was clearly cared for and nicely maintained, but things were far from perfect, and I've sorted nearly all of these issues out, as well as modified it a crapload more, so it's a much bigger spec than when I bought it in every aspect.
Here's the issues...
ENGINE
The engine was pissing out oil from around the cams, common problem, so I replaced the half moon cam oil seals and cam cover gasket, job done. While I was at it I stripped the shitty paint off the cam cover so now it's bare alloy and looks way better.
The engine was at claimed Stg1 270bhp spec, and it did have the typical mods for this fitted, but the car felt SLOW, it had decent torque, but I'm not even sure it was 200bhp to be honest.
The main issue was there was literally ZERO airflow to the intercooler. 100% of it was sitting behind a totally solid bit of the MX5 front bumper, which was ridiculous, so I fitted a charge temp gauge and it was over 70degC! The simple solution to this was to cut a letterbox shape hole the same size as the intercooler, and the instant result was a massive boost in performance, but it still didn't seem right.
A friend of mine noticed how much the bonnet was trying to raise at speed, and that made us think of something else- It looked like the air was struggling to get out, so I vented the bonnet just behind the intercooler, and added alloy plates to create a duct which forced air THROUGH the intercooler rather than letting it go around it, and once again, the power went up by a very noticable amount, and charge temps now never go over 30degC!
Next up was to bin off the god awful rear exhaust section someone had fitted to the otherwise really nice 3in system. I replaced it with a 3in rear section and as well as sounding like a Cosworth at last, to the extent that to be honest it's probably the right power it should be for the spec now.
It still felt a little unresponsive though, and while I couldn't see any big problems, I wasn't that happy with the inlet setup, and I've had good luck with proper bellmouth inlets (in fact it's a very underestimated thing, but anyhow), so I removed the compressor housing and ported the inlet from a 5mm step to a smooth bellmouth, and on the end of that I fitted a large alloy bellmouth with the air filter fitted directly do it. While power didn't really change that I felt, throttle response was massively improved to more like how I expected it to be.
Another thing the previous owner mentioned was after coming off track and turning the engine off, it would bubble over and spit some water out the header tank overflow. Not a lot, but some. I did notice this myself, but the car didn't have a expansion/overflow tank, so refitted a standard MX5 one. But something still wasn't quite right, and then I noticed the header tank pressure cap was shagged, so swapped the header tank for a Audi 1.8T item. It was fine for a bit, but started to have overheating issues again, and turns out the thermostat was slowly knackering up, and finally was shagged and jammed shut. Replaced it with a modified new one (few holes drilled for increased flow), and all is lovely now.
TRANSMISSION
The previous owner said about the diff being mounted very low, and to be fair the Cossie diff is a big fucker compared to the weedy standard one, but it was VERY low, not much more than an inch off the ground, and the driveshafts and prop were at a right spazzy angle because of it too. It turned out most the reason it was so low was the rear diff mount was made of an old tin can or something, far too thin for a diff mount, and was bent, and just before we went to change it, it completely snapped. A new one was made from 5mm thick plate, and now the diff sits at least 2in higher than when I bought it, making it a lot easier to drive on UK roads.
The Cosworth 7.5" diff is a viscous LSD, which is never great, and this one was awful, barely any better than an open diff, made handling and grip pretty crappy to be fair. It was removed and welded up, and now grip and handling is 100 times better, in fact it's the one mod that made me love the car.
SUSPENSION
The geometry when I bought it was ridiculous. Maximum rear camber and no front camber at all?! Now it's got front camber and as little on the rear as we could get. As you might imagine, the handling is transformed.
Anyhow, full spec, anything with a * is stuff I've done in the last 6months or so...
1990 1.6 MX5 (Still 1.6 on the logbook!), 12months MOT, 6months Tax
Engine-
1990 2wd Sapphire RS Cosworth head and block, standard, new half moon oil seals and cam cover gasket.
4x4 Sapphire RS Cosworth exhaust manifold.
Standard Yellow injectors.
4x4 Saph Cossie Garrett T3 turbo with ported compressor inlet.
Custom 3in turbo-back exhaust engine, no silencers, ending in 45deg downturned 3in tailpipe*
4x4 Saph Cossie intercooler.
Forge Motorsport alloy inlet bellmouth with Green cone filter*
L6 ECU with Stg1 Chip.
Custom radiator.
Bailey oil breather system.
Spec-R swirlpot*
Audi 1.8T header tank*
New thermostat with added holes for extra flow*
Running 17psi peak, 15psi held using standard Cosworth Amal valve.
7500rpm rev limit.
Transmission-
2wd Cosworth Borg Warner T5 gearbox
New Cosworth clutch cable*
2wd Cosworth 7.5in diff, welded*
Custom propshaft and driveshafts.
Solidly mounted rear diff with uprated mount*
Brakes-
1.8 MX5 brakes front and rear, with braided brake lines.
Suspension + Steering-
Kayaba AGX shocks and springs with adjustable damping.
Recent suspension alignment to track/drift spec*
Kev Lee modified hubs with reduced Ackerman angle and massive steering lock*
Sierra RS Cosworth power steering pump.
Modified/strengthened and solidly mounted rear subframe.
Uprated/poly steering rack bushes*
Exterior-
Originally blue, painted white at some point in its life, now with black bonnet, black bootlid, black hard top, black mirrors, black rear light panel, black front indicator vents*
Vented aluminium bonnet, with functional and very effective vents (From a Pontiac Trans Am!), front ones for intercooler/radiator air, side ones for engine/turbo.*
Hard top.
Indicator vents.*
Vented bumper.*
Mk3 Golf GTI front splitter.*
Undersealed and garaged almost all it's life.
Interior-
Fully stripped out and painted black.
Hard Dog rear roll cage.
Sparco drivers bucket seat.*
Flyoff handbrake button.*
Boost gauge.
Inlet charge temp gauge.*
Momo steering wheel.
Battery mounted in the centre of boot (in wheel well).
Blowers, but no heater (easy to replace if needed, just a few pipes, and is room to do so).
Wheels + Tyres-
7x15 ET23 BBS wheels from a E30 325i painted satin black.*
Have 2x sets, one on 195/50x15 road tyres, the other fitted with 205/50x15 road legal tarmac rally tyres (almost new). Can have either or both sets, depending on price.*
The car is VERY fast, handles awesomely, and drifts brilliantly, it's the most fun car I've had since, well, my Cosworth over 10 years ago. Being an MX5, nobody expects it to be fast either, so it's a great sleeper, everyone wants to race, and everyone is gutted when they lose. Motorbikes, Lotus Carlton, M5, and lots more have been very very surprised...
Will happily and quite easily pull 7000rpm+ in 5th gear, which is 160mph+, in fact it's about 170mph on the rev limiter (Real speed, not speedo speed).
The car has also been HUGELY reliable. Driven to drift days and back, 100+mile each way journeys, no problem at all, including getting hammered all day. Has been my daily driver most days, purely as it's so much fun I choose it over anything else! Pretty good on fuel as it's so light to be honest.
Best of all, the engine is almost standard, it's almost criminal to leave a YB so standard, it's not even trying at it's current level, but this means lots more power is easy to get. In fact I have almost all the bits for a Stage3 300bhp+ setup I was about to fit...
PICS!!!!
ON TRACK PICS!
BAD POINTS! (Tbh they were all there when I bought the car, but so minor they've never bothered me...
The car is VERY hardcore. It's loud, its stripped bare, its got solidly mounted subframe and diff, so especially on the overrun, it fucking vibrates like mad. If you not used to full race cars with solid everything, you may be in for a surprise lol.
The white respray was done 'track car spec' ie it's pretty poor. It's very thin, it's now cracking/crazing/pitting, and it's got various scratches etc too. Aside from to help de-gay the car, the reason I added so many black panels was to hide the white paint. As per usual track car spec, it looks fine from a couple feet away, but up close, it's not good at all, it's bad in fact lol.
One headlamp, while it will pop up, it wont go back down, expect its just a dead relay. I run the car with them up 24/7, so it doesn't bother me.
Passenger electric window dont go down, drivers one only a couple of inches- Worn motors most likely, an easy/cheap fix, but never bothered me.
Needs IMO an oil pressure and oil temp gauge.
It actually has the stock gauge, but some aftermarket sensor fitted so it doesnt actually work properly, just reads random, lol.
We fitted a mechanical gauge for a while just to check its got good pressure, it has got great cold and hot pressure, but would be good to keep an eye on it with a gauge like any track car.
Speedo doesn't work, needs a new cable I think, never bothered me either.
Tappets can sometimes be randomly tappy for a few secs, but mostly dead quiet. New tappets and cheap, but never bothered me as it's not constantly.
Usual 2wd Cossie YB piston slap due to forged pistons on cold start, but literally just for 3sec or so, just like when they were new.
That's it I think?
The guy I bought it off was asking the same money I am now, and now it's a LOT better than when he sold it. Considering how much Cossie engine/box/diffs/ecu/loom setup is worth, this is a bargain, and cheap to run and insure too!
£4000
Car is based in Cheltenham and/or Gloucester, just off A40 and M5.
Also have loads of parts I could possibly sell with it for the right price- L8 ECU, Green injectors, 3bar MAP sensor (new), 4x4 TPS (new), Collins/Pectel pro monitor, Cat Cams vernier pulleys (new), etc etc- Just need a suitable chip and that's Stg3 300bhp+ 300lbft+ crazy spec.
PRICE-£4000ono
This mad thing...
Originally converted by Roddisons Motorsport (MX5 Racing - Roddisons Motorsport) a long long time ago (10yrs+?), the car has been a dedicated track car (not even road legal) for most of its life, but the previous owner re-made it road legal and drove it to Europe for track days. Because of it never actually really being a road car until I bought it in March this year, it's done very little miles, though exactly how many, I've no idea, but what it does mean, is rust wise, it's in damn good condition as it's never seen winter salty roads etc.
The conversion makes a lot of sense, especially compared to all these SR20 conversions people dream about etc, as the sump etc etc is in the correct place, so it all fits nicely with little to no mods.
As well as being fitted with one of the best, strongest, and most tunable 2ltr engines ever made, the Ford YB Cosworth, it's got one of the strongest RWD boxes too, the Cosworth spec Borg Warner T5, and a mega strong diff too, a 7.5" 2wd Cosworth one- Basically, unlike most MX5s, this one has a bulletproof engine and transmission.
You have no worries about the diff mounts or subframe breaking either, as it's all hugely modified/strengthened and solidly mounted too.
When I bought the car it was clearly cared for and nicely maintained, but things were far from perfect, and I've sorted nearly all of these issues out, as well as modified it a crapload more, so it's a much bigger spec than when I bought it in every aspect.
Here's the issues...
ENGINE
The engine was pissing out oil from around the cams, common problem, so I replaced the half moon cam oil seals and cam cover gasket, job done. While I was at it I stripped the shitty paint off the cam cover so now it's bare alloy and looks way better.
The engine was at claimed Stg1 270bhp spec, and it did have the typical mods for this fitted, but the car felt SLOW, it had decent torque, but I'm not even sure it was 200bhp to be honest.
The main issue was there was literally ZERO airflow to the intercooler. 100% of it was sitting behind a totally solid bit of the MX5 front bumper, which was ridiculous, so I fitted a charge temp gauge and it was over 70degC! The simple solution to this was to cut a letterbox shape hole the same size as the intercooler, and the instant result was a massive boost in performance, but it still didn't seem right.
A friend of mine noticed how much the bonnet was trying to raise at speed, and that made us think of something else- It looked like the air was struggling to get out, so I vented the bonnet just behind the intercooler, and added alloy plates to create a duct which forced air THROUGH the intercooler rather than letting it go around it, and once again, the power went up by a very noticable amount, and charge temps now never go over 30degC!
Next up was to bin off the god awful rear exhaust section someone had fitted to the otherwise really nice 3in system. I replaced it with a 3in rear section and as well as sounding like a Cosworth at last, to the extent that to be honest it's probably the right power it should be for the spec now.
It still felt a little unresponsive though, and while I couldn't see any big problems, I wasn't that happy with the inlet setup, and I've had good luck with proper bellmouth inlets (in fact it's a very underestimated thing, but anyhow), so I removed the compressor housing and ported the inlet from a 5mm step to a smooth bellmouth, and on the end of that I fitted a large alloy bellmouth with the air filter fitted directly do it. While power didn't really change that I felt, throttle response was massively improved to more like how I expected it to be.
Another thing the previous owner mentioned was after coming off track and turning the engine off, it would bubble over and spit some water out the header tank overflow. Not a lot, but some. I did notice this myself, but the car didn't have a expansion/overflow tank, so refitted a standard MX5 one. But something still wasn't quite right, and then I noticed the header tank pressure cap was shagged, so swapped the header tank for a Audi 1.8T item. It was fine for a bit, but started to have overheating issues again, and turns out the thermostat was slowly knackering up, and finally was shagged and jammed shut. Replaced it with a modified new one (few holes drilled for increased flow), and all is lovely now.
TRANSMISSION
The previous owner said about the diff being mounted very low, and to be fair the Cossie diff is a big fucker compared to the weedy standard one, but it was VERY low, not much more than an inch off the ground, and the driveshafts and prop were at a right spazzy angle because of it too. It turned out most the reason it was so low was the rear diff mount was made of an old tin can or something, far too thin for a diff mount, and was bent, and just before we went to change it, it completely snapped. A new one was made from 5mm thick plate, and now the diff sits at least 2in higher than when I bought it, making it a lot easier to drive on UK roads.
The Cosworth 7.5" diff is a viscous LSD, which is never great, and this one was awful, barely any better than an open diff, made handling and grip pretty crappy to be fair. It was removed and welded up, and now grip and handling is 100 times better, in fact it's the one mod that made me love the car.
SUSPENSION
The geometry when I bought it was ridiculous. Maximum rear camber and no front camber at all?! Now it's got front camber and as little on the rear as we could get. As you might imagine, the handling is transformed.
Anyhow, full spec, anything with a * is stuff I've done in the last 6months or so...
1990 1.6 MX5 (Still 1.6 on the logbook!), 12months MOT, 6months Tax
Engine-
1990 2wd Sapphire RS Cosworth head and block, standard, new half moon oil seals and cam cover gasket.
4x4 Sapphire RS Cosworth exhaust manifold.
Standard Yellow injectors.
4x4 Saph Cossie Garrett T3 turbo with ported compressor inlet.
Custom 3in turbo-back exhaust engine, no silencers, ending in 45deg downturned 3in tailpipe*
4x4 Saph Cossie intercooler.
Forge Motorsport alloy inlet bellmouth with Green cone filter*
L6 ECU with Stg1 Chip.
Custom radiator.
Bailey oil breather system.
Spec-R swirlpot*
Audi 1.8T header tank*
New thermostat with added holes for extra flow*
Running 17psi peak, 15psi held using standard Cosworth Amal valve.
7500rpm rev limit.
Transmission-
2wd Cosworth Borg Warner T5 gearbox
New Cosworth clutch cable*
2wd Cosworth 7.5in diff, welded*
Custom propshaft and driveshafts.
Solidly mounted rear diff with uprated mount*
Brakes-
1.8 MX5 brakes front and rear, with braided brake lines.
Suspension + Steering-
Kayaba AGX shocks and springs with adjustable damping.
Recent suspension alignment to track/drift spec*
Kev Lee modified hubs with reduced Ackerman angle and massive steering lock*
Sierra RS Cosworth power steering pump.
Modified/strengthened and solidly mounted rear subframe.
Uprated/poly steering rack bushes*
Exterior-
Originally blue, painted white at some point in its life, now with black bonnet, black bootlid, black hard top, black mirrors, black rear light panel, black front indicator vents*
Vented aluminium bonnet, with functional and very effective vents (From a Pontiac Trans Am!), front ones for intercooler/radiator air, side ones for engine/turbo.*
Hard top.
Indicator vents.*
Vented bumper.*
Mk3 Golf GTI front splitter.*
Undersealed and garaged almost all it's life.
Interior-
Fully stripped out and painted black.
Hard Dog rear roll cage.
Sparco drivers bucket seat.*
Flyoff handbrake button.*
Boost gauge.
Inlet charge temp gauge.*
Momo steering wheel.
Battery mounted in the centre of boot (in wheel well).
Blowers, but no heater (easy to replace if needed, just a few pipes, and is room to do so).
Wheels + Tyres-
7x15 ET23 BBS wheels from a E30 325i painted satin black.*
Have 2x sets, one on 195/50x15 road tyres, the other fitted with 205/50x15 road legal tarmac rally tyres (almost new). Can have either or both sets, depending on price.*
The car is VERY fast, handles awesomely, and drifts brilliantly, it's the most fun car I've had since, well, my Cosworth over 10 years ago. Being an MX5, nobody expects it to be fast either, so it's a great sleeper, everyone wants to race, and everyone is gutted when they lose. Motorbikes, Lotus Carlton, M5, and lots more have been very very surprised...
Will happily and quite easily pull 7000rpm+ in 5th gear, which is 160mph+, in fact it's about 170mph on the rev limiter (Real speed, not speedo speed).
The car has also been HUGELY reliable. Driven to drift days and back, 100+mile each way journeys, no problem at all, including getting hammered all day. Has been my daily driver most days, purely as it's so much fun I choose it over anything else! Pretty good on fuel as it's so light to be honest.
Best of all, the engine is almost standard, it's almost criminal to leave a YB so standard, it's not even trying at it's current level, but this means lots more power is easy to get. In fact I have almost all the bits for a Stage3 300bhp+ setup I was about to fit...
PICS!!!!
ON TRACK PICS!
BAD POINTS! (Tbh they were all there when I bought the car, but so minor they've never bothered me...
The car is VERY hardcore. It's loud, its stripped bare, its got solidly mounted subframe and diff, so especially on the overrun, it fucking vibrates like mad. If you not used to full race cars with solid everything, you may be in for a surprise lol.
The white respray was done 'track car spec' ie it's pretty poor. It's very thin, it's now cracking/crazing/pitting, and it's got various scratches etc too. Aside from to help de-gay the car, the reason I added so many black panels was to hide the white paint. As per usual track car spec, it looks fine from a couple feet away, but up close, it's not good at all, it's bad in fact lol.
One headlamp, while it will pop up, it wont go back down, expect its just a dead relay. I run the car with them up 24/7, so it doesn't bother me.
Passenger electric window dont go down, drivers one only a couple of inches- Worn motors most likely, an easy/cheap fix, but never bothered me.
Needs IMO an oil pressure and oil temp gauge.
It actually has the stock gauge, but some aftermarket sensor fitted so it doesnt actually work properly, just reads random, lol.
We fitted a mechanical gauge for a while just to check its got good pressure, it has got great cold and hot pressure, but would be good to keep an eye on it with a gauge like any track car.
Speedo doesn't work, needs a new cable I think, never bothered me either.
Tappets can sometimes be randomly tappy for a few secs, but mostly dead quiet. New tappets and cheap, but never bothered me as it's not constantly.
Usual 2wd Cossie YB piston slap due to forged pistons on cold start, but literally just for 3sec or so, just like when they were new.
That's it I think?
The guy I bought it off was asking the same money I am now, and now it's a LOT better than when he sold it. Considering how much Cossie engine/box/diffs/ecu/loom setup is worth, this is a bargain, and cheap to run and insure too!
£4000
Car is based in Cheltenham and/or Gloucester, just off A40 and M5.
Also have loads of parts I could possibly sell with it for the right price- L8 ECU, Green injectors, 3bar MAP sensor (new), 4x4 TPS (new), Collins/Pectel pro monitor, Cat Cams vernier pulleys (new), etc etc- Just need a suitable chip and that's Stg3 300bhp+ 300lbft+ crazy spec.
Last edited by WTF?!; 13-10-2013 at 03:34 PM.
13-10-2013, 03:02 PM
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Yeah it's pretty mental as it is as it weighs 1000kg I'd say anyhow (Standard MX5s of that age, with no options, were 980kg, and the Cossie bits haven't really added any weight), enough to make lots of fast/super cars/bikes look very silly, but with the Stg3 parts that I was about to fit, well, it'd be bloody ridiculous.
I know I should be pleased my other project it coming along so fast, but I wish it was taking longer as needing funds for that means I got to get rid of this, and I bloody love it!
I know I should be pleased my other project it coming along so fast, but I wish it was taking longer as needing funds for that means I got to get rid of this, and I bloody love it!
13-10-2013, 03:03 PM
#4
Ben
Awesome bit of kit, I hope the money is going towards the FC?!
13-10-2013, 03:28 PM
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what a leightweight....... with a big spec yb in it it will fly 
05-11-2013, 11:33 AM
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Local lad down this way.
He was totally new to YBs etc etc so I gave him a list of dos and donts and contacts so he dont get ripped off or ruin it- It's such a little weapon it'd be a shame for it to get wrecked.
He was totally new to YBs etc etc so I gave him a list of dos and donts and contacts so he dont get ripped off or ruin it- It's such a little weapon it'd be a shame for it to get wrecked.
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