300hp MX5 (mk2)

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Discussion

TheJimi

Original Poster:

25,565 posts

249 months

Monday 5th May 2014
quotequote all
Tell me how *you* would achieve that.

It can be a force inducted 1.8 or an engine transplant of some sort, but either way, I'm looking for inspiration & ideas.

Cost details would be good too.

Some background: My Mk2 1.8 is a '98 car in near immaculate condition, with only 64k on the clock. Optimistically, it's worth maybe 2k ish? So my rationale is that it's not worth flogging such a nice example for that little, so I'm looking at options of what to do with it.

Ideas are ranging from chucking a grand at it with some small tweaks here and there, to throwing sensibilities to the wind and turning it into something really interesting.

rs4al

950 posts

171 months

Monday 5th May 2014
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Iirc anything over 250hp needs a forged engine, otherwise stick a V8 in it, flyin miata and mx5nutz are a good place to start your research.

Planet Claire

3,345 posts

215 months

Monday 5th May 2014
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Gaz Guzzler over on PlanetMX5 is selling his V8 mk1, but failing that he's going to sell the engine separately, if you're interested in going down that route. I also know someone who is wanting to sell their MP62 supercharger (from a mk2) and also has a TDR intercooler up for sale. As the poster above said, look on MX5Nutz for all things FI.

TheJimi

Original Poster:

25,565 posts

249 months

Monday 5th May 2014
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Aware of Nutz etc, just wanted someone opinions really smile

snotrag

14,829 posts

217 months

Monday 5th May 2014
quotequote all
Forged engine. A megasquirt.
Then a large payment to flyin miata and wait for your 300bhp to arrive in the post.

snotrag

14,829 posts

217 months

Monday 5th May 2014
quotequote all
Forged engine. A megasquirt.
Then a large payment to flyin miata and wait for your 300bhp to arrive in the post.

MX-5 Lazza

7,952 posts

225 months

Tuesday 6th May 2014
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I wouldn't bother aiming for over 250bhp. 250 is plenty to make it quicker than most other cars you will meet and it will keep up with proper "supercars" on the road. Aiming for over 250bhp means a fully built engine which will at least double the price for very little realistic gain.

Richyvrlimited

1,837 posts

169 months

Tuesday 6th May 2014
quotequote all
TheJimi said:
Tell me how *you* would achieve that.

It can be a force inducted 1.8 or an engine transplant of some sort, but either way, I'm looking for inspiration & ideas.

Cost details would be good too.

Some background: My Mk2 1.8 is a '98 car in near immaculate condition, with only 64k on the clock. Optimistically, it's worth maybe 2k ish? So my rationale is that it's not worth flogging such a nice example for that little, so I'm looking at options of what to do with it.

Ideas are ranging from chucking a grand at it with some small tweaks here and there, to throwing sensibilities to the wind and turning it into something really interesting.
Ger someone with an MX5 with FI already added before you start flinging numbers around.

220 - 250 is perfectly achievable on the stock motor reliably and is damn quick.

Remember the MX5 weighs circa 1 ton, whereas modern cars whilst having higher outputs weigh much much more.

I've had a joyride in a 300bhp+ MX5, it was a dry hot summers day, and it span up 3rd gear like it was 1st in the wet.

Google [bot]

6,692 posts

187 months

Tuesday 6th May 2014
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Another 'I wouldn't bother going that high' post. I had a run in a 320rwhp mk1 and didn't particularly enjoy 3rd gear on-boost straight line squirming around.

g40steve

960 posts

168 months

Wednesday 7th May 2014
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I'd be wary of doing anything with a mk2 unless rot free after seeing all the horror photos.

Aphex

2,160 posts

206 months

Wednesday 7th May 2014
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How much are sr20dets going for these days?

skinny

5,269 posts

241 months

Wednesday 7th May 2014
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i'd go pretty standard - fully forged, big turbo, megasquirt.
might start getting to teh limit of the stock 6-speed box and torsen diff towards 300bhp tho, so that might affect the decision.

Then again, engine transplant, new box, and new diff, brings its own complexity.

i'd not get too hung up on teh numbers, rather build to the realistic spec of standard parts. the difference between 280 and 300bhp is probably not huge in teh real world.

fatjon

2,298 posts

219 months

Wednesday 7th May 2014
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Done 10k miles now on six speed with the cars original 99-00 LSD without any problems. Just over 300HP at 20 PSI on the dyno with GT2836RS turbo and Megasquirt. Manley rods and Wossner low compression pistons and a slightly upgraded oil pump (steel rotors). Clutch is a weak point, the slightly upgraded organic lasted 3000 miles and I'm now on a paddle clutch which is surprisingly civilised. Car was rotten as a peach so have started grafting it all onto an new Exocet chassis. Should be fun for a track day.

It's fair to say I don't hammer the hell out of my cars so the fact that the diff and box are OK may not be an indication that they will be OK for everyone.






rotarymazda

538 posts

171 months

Wednesday 7th May 2014
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TheJimi said:
Tell me how *you* would achieve that.
My Mk1 already has a 240bhp ported rotary in it so I would get a small turbo added, 5 psi should be enough to get past 300bhp.

TheJimi

Original Poster:

25,565 posts

249 months

Wednesday 7th May 2014
quotequote all
rotarymazda said:
TheJimi said:
Tell me how *you* would achieve that.
My Mk1 already has a 240bhp ported rotary in it so I would get a small turbo added, 5 psi should be enough to get past 300bhp.
How difficult was the rotary conversion?

TheJimi

Original Poster:

25,565 posts

249 months

Wednesday 7th May 2014
quotequote all
fatjon said:
Done 10k miles now on six speed with the cars original 99-00 LSD without any problems. Just over 300HP at 20 PSI on the dyno with GT2836RS turbo and Megasquirt. Manley rods and Wossner low compression pistons and a slightly upgraded oil pump (steel rotors). Clutch is a weak point, the slightly upgraded organic lasted 3000 miles and I'm now on a paddle clutch which is surprisingly civilised. Car was rotten as a peach so have started grafting it all onto an new Exocet chassis. Should be fun for a track day.

It's fair to say I don't hammer the hell out of my cars so the fact that the diff and box are OK may not be an indication that they will be OK for everyone.
300hp in an Exocet would be interesting!

rotarymazda

538 posts

171 months

Wednesday 7th May 2014
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TheJimi said:
rotarymazda said:
TheJimi said:
Tell me how *you* would achieve that.
My Mk1 already has a 240bhp ported rotary in it so I would get a small turbo added, 5 psi should be enough to get past 300bhp.
How difficult was the rotary conversion?
Turned out to be very difficult. Very little space to get the exhaust out. Mine is LHD but it would be even harder on a RHD. No room either for power steering or A/C.

dblack1

230 posts

167 months

Tuesday 13th May 2014
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300 at the crank with a stock bottom end isn't totally unrealistic, but 300 at the wheels is a different story. 250 at the wheels is about the upper limit of the stock bottom end. V8 isn't the only swap option either... There are people swapping in rotaries and v6s... As for realistic, you will have cooling issues with a rotary producing any real power in that car, and for a V engine, quadcam engines will be super trouble to fit. Flyin Miata puts LS motors in, which aren't too common in europe. Anything cast iron will weigh down the front of the car enough to effect handling. I would think a rover V8 would fit fairly easily, but I don't know what trans or rear end you would use. In the US, people pay more than the value of their car to get 300 hp at the wheels and that's doing the work yourself, it will be more expensive in the UK just because the options are different.

cianha

2,165 posts

203 months

Thursday 15th May 2014
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