mx5cartalk.com

hey guys, looking at getting some work done on the 5.

im considering a bottom end rebuild including putting in a set of wiseco 11 to 1 hi comp pistons ( would nb8b pistons be an option given they are 10 to 1 compared to nb8a's 9??) , port and polish etc on the head (maybe even a little shave???) and a set of 805c cams. (exhaust and ecu aleadry done)

will the car be a pig to drive on a daily basis, in a bit of traffic or just in a complete traffic jam??

i realise my fuel economy wont be great (ecu has already cost me 50-75km a tank) but any idea on how bad it might be even dríven gently??

thanks in advance guys

Ben

p.s i can hear the fi boys already calling for blood because im going na, but given my driving style i feel a turbo would mean either myself or someone else would be dead within 12months.

i would think it should be nicer to drive? have more torque at lower revs but also might need a better grade petrol.

like how modern turbo cars have high compression engines for more off boost low rev torque but run lower boost on the turbo so it won't ping. whereas in the older days the trend was lower compression engine with more turbo boost.

Contact Red 2f MX5 or ring him at Peninsular Sportscars.
He built an engine like this for his race car so he's in the best position to offer you advice. Ended up with around 115rwkW from memory.

thanks for the info guys,

if i remember correctly supermazdakart, the highest grade fuel you can buy from a servo these days is 98octane (shell stopped doing their 100octane blend). 98 is ALL I EVER RUN in the car since ive had it. might be time to keep a bottle of octane booster in the car once its done

chees guys

ben

maybe consider getting it built for ethanol

My bike is up near 12:1 compression ratio and it runs fine on 95RON. It's all in the tuning.

Garry wrote:My bike is up near 12:1 compression ratio and it runs fine on 95RON. It's all in the tuning.

Exactly, tuning, knock sensor and how smart the ecu is I assume.

If there were more E85 outlets I could suggest you get setup with two tunes. One for 98RON petrol and one for the E85 brew which has an octane closer to 115RON!

Also, United fuels have a 100RON available.

805C cams are pretty mild, doubt it will be a pig. Big cam profiles make cars people as they can't idle at low revs. I very much doubt anyone made 115rwkw on this setup. You need bigger comp, bigger lift cams and far more engine work to get into that zone. Maybe 105rwkw will be achievable depending on the dyno. As for drivability throught traffic, should be fine until you fit a lighter flywheel, which you should....then it will start to get uncomfortable in smow moving traffic. High performance cars are most always a compromise.