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34 Posts
Hi all, long time lurker, infrequent poster looking for some advice from those in the know.
I've had my V-spec 1994 for a long time now and have spent the last 2 years doing a nut and bolt restoration on the car to get the chassis, exterior, rust protection and interior all sorted. A few years ago my engine went kaput so I swapped in a 35k 2004 NBFL VVT motor to give myself a bit more power. After that I went about buying some of the bits for a M42 supercharger setup, TR lane mounting hardware, teflon supercharger etc in order to fit that.
Since then I've sort of mellowed on the idea of a supercharger and never fitted the kit I bought or got the last few components to complete it, plus life got in the way. Now that I'm back on the horse however, I've started to revisit the idea of getting a bit more oomph out of the engine without going FI.
After the rebuild a couple of months ago I got the car mapped at DanST engineering near me and the car made 153bhp at the crank with only minor mods -silenced decat, 4-2-1 manifold, cobalt exhaust, pipercross panel filter and a tune on the ME221 gen2 I'm running.
Now this car seems to have a pretty healthy engine that's making good power, and my car is strictly for the road and won't be tracked, so I'm not looking for insane power, but I want purity and driveability. With that in mind I'm considering scrapping the FI route and going for NA power instead. I know these engines are crap for high bhp figures NA so I'm being realistic and looking to get about 170-180 at the crank, whilst keeping the car relatively civilised for weekend drives, occasional commuting in summer and the odd road trip here and there.
Dan makes throttle body kits which I'm sure you're all aware of, so I was considering fitting one of those and then purchasing a second head with the intention of porting and polishing, a slight head skim, fitting a set of cat cams 278/278, vernier pulley on the exhaust side, supertech +1mm valves and springs and a harmonic balancer. I want to keep all the work in the head rather than in the block so future engine repairs will (hopefully) be kept fairly straightforward and simple. I've never built an engine before so this would be done over a period of a few years in all likelihood, with the ITB's being fitted to the engine as-is and then a head being built, learning as I go after doing lots and lots of learning and reading!
My question is, before I go spending any money and wasting lots of time is would it be worth the hassle? Bearing in mind the fact I'm not chasing numbers but am aiming for around 180bhp on the upper end, and that I'm going for the driving experience on country roads where I can wring it out to 7500rpm without losing my license or my life, would I be stupid to attempt all this whilst keeping the car relatively streetable?
My alternative option is to save circa 5k for a rotrex and be done with it, making 200-220 without any issues, but I'm a sucker for a screamer of an engine and the instant throttle response and crispness of an NA engine. The Mx5 is such a well balanced car that I would only want to enhance that sense of balance, rather than go chasing big power figures.
Given what I've said, am I being as realistic as I think I am, or am I just going to end up down a rabbit hole of costs and dissapointment?!
Pictures of my build so far attached for your perusal, and all your advice is much appreciated!
Cheers,
Alex
I've had my V-spec 1994 for a long time now and have spent the last 2 years doing a nut and bolt restoration on the car to get the chassis, exterior, rust protection and interior all sorted. A few years ago my engine went kaput so I swapped in a 35k 2004 NBFL VVT motor to give myself a bit more power. After that I went about buying some of the bits for a M42 supercharger setup, TR lane mounting hardware, teflon supercharger etc in order to fit that.
Since then I've sort of mellowed on the idea of a supercharger and never fitted the kit I bought or got the last few components to complete it, plus life got in the way. Now that I'm back on the horse however, I've started to revisit the idea of getting a bit more oomph out of the engine without going FI.
After the rebuild a couple of months ago I got the car mapped at DanST engineering near me and the car made 153bhp at the crank with only minor mods -silenced decat, 4-2-1 manifold, cobalt exhaust, pipercross panel filter and a tune on the ME221 gen2 I'm running.
Now this car seems to have a pretty healthy engine that's making good power, and my car is strictly for the road and won't be tracked, so I'm not looking for insane power, but I want purity and driveability. With that in mind I'm considering scrapping the FI route and going for NA power instead. I know these engines are crap for high bhp figures NA so I'm being realistic and looking to get about 170-180 at the crank, whilst keeping the car relatively civilised for weekend drives, occasional commuting in summer and the odd road trip here and there.
Dan makes throttle body kits which I'm sure you're all aware of, so I was considering fitting one of those and then purchasing a second head with the intention of porting and polishing, a slight head skim, fitting a set of cat cams 278/278, vernier pulley on the exhaust side, supertech +1mm valves and springs and a harmonic balancer. I want to keep all the work in the head rather than in the block so future engine repairs will (hopefully) be kept fairly straightforward and simple. I've never built an engine before so this would be done over a period of a few years in all likelihood, with the ITB's being fitted to the engine as-is and then a head being built, learning as I go after doing lots and lots of learning and reading!
My question is, before I go spending any money and wasting lots of time is would it be worth the hassle? Bearing in mind the fact I'm not chasing numbers but am aiming for around 180bhp on the upper end, and that I'm going for the driving experience on country roads where I can wring it out to 7500rpm without losing my license or my life, would I be stupid to attempt all this whilst keeping the car relatively streetable?
My alternative option is to save circa 5k for a rotrex and be done with it, making 200-220 without any issues, but I'm a sucker for a screamer of an engine and the instant throttle response and crispness of an NA engine. The Mx5 is such a well balanced car that I would only want to enhance that sense of balance, rather than go chasing big power figures.
Given what I've said, am I being as realistic as I think I am, or am I just going to end up down a rabbit hole of costs and dissapointment?!
Pictures of my build so far attached for your perusal, and all your advice is much appreciated!
Cheers,
Alex









