Which post are you refering to Rich?
Hi Geoff,
I was referring to your one about the 20bhp lost in transmission. Probably just wishful thinking on my part, hoping that they were referring to the flywheel.
Right, the car has been checked over by the garage and i have receivd the following by e-mail:
All cylinder compressions are ok number 1 is 185. 2 is 180. 3 is 185. 4 is 185.
You have your original injectors & manifold fitted to your car.
Exhaust emissions are what you would expect for a vehicle with no cat, 0.70% on idle & 0.93 @ 3000 rpm. Have rechecked timing & dropped it back to 16 have tested it & it seems to drive ok.
Cylinder compression seems more than fine, those figures are excellent! Leaving the factory they are supposed to be 182psi. On a used car as long as they are above 128psi and there is not a difference of more than 28psi between cylinders that is deemed ok.
I queried the state of the injectors on the advice of someone on MX5nuts, but it appears that the old ones have been used and should be ok. Plus the emissions seem ok.
So WHY, was the car so underpowered at 10 & 14 degrees BTDC? I haven’t got the car back yet, so i can’t make a judgement myself on how the car is driving, but that graph from the rolling road with the car at 14 degrees cannot be normal!!
Rich, I would take it to another dyno shop if you are really unhappy. First though, get a ride in a couple of other similar spec cars to yours, it may all be in the mind.
The comments about the 20bhp refered to the figs you published from the dyno company. The top figure quoted 109 bhp at the wheels and 129bhp at the flywheel. This is a perfectly normal set of figures
Thought i’d bump this up and see if anyone had ideas and opinions to share…
I’ve decided to have the timing set back to stock as i can’t afford to keep paying for high octane V Power at the current price of petrol and I’m hoping the performance doesn’t suffer too much as per the original post and the Dyno Run.
I have just come across this and wondered what the liklihood that my timing has been accidentally retarded by my garage using the wrong mark on the CAS to set timing?
http://www.flyinmiata.com/techline/older_archives.asp
“The other (important) difference from the 1.6 engine is that there are two marks on the crankshaft pulley. Contrary to what Mazda’s shop manual says (possibly corrected by now), you have to use the yellow mark for 10 BTDC, NOT the white one (TDC)”.
<o:p>Does anyone who might know think that the lower Dyno run could be consistent with a 1.8 with the timing retarded to say 4 degrees BTDC? The timing on the frist run was supposed to be 14 Deg BTDC, but if they used the white mark it may have been set to 4…</o:p>
<o:p></o:p>
<o:p>And given that the timing on the higher run was purportedly set to 19 deg, it may infact have been 9 degrees - which would explaing the much better torque curve and top end power…</o:p>
<o:p></o:p>
<o:p>I would be very interested in what people think!</o:p>
cam belt misaligned…Its only got to be one tooth out and the car car will run but will be low on power
if the exhaust is lifting as fuel is still being burnt this would go some way to explaining the richness.
I would check the pulley wheels for alignment.
then replace plugs and Ht leads …Maybe a weak spark.Or the wrong plugs??
Fit an arc kit…More midrange grunt
Cold air intake.
I have seen several 1.8 of your cars age and with Higher mileage make the Money 130BHP at the wheels.
Mine included
and as it is now.
Hope some of this helps.
Alan
Thanks Alan, i will certainly ask the relevant questions and hopefully get the right answers when i take it into the garage.
Those figure for yours are pretty sweet, i was quite impressed the way you pulled away from me at Silverstone in Uma, was she at 189.5hp at the time?
I’d love to get the M45 on mine one day. 
If it was since last september then yes.
Car went very well without it if you can get the engine to breath and rev ok…
Alan
It was at the MOT Silverstone day at the begininng of march. i just got used to pulling over to the right!
Dyno figures of my Cal
sorry about the shine it topped out at 131bhp. This is the pre 95 low compression engine with induction kit and 4-2-1 jap manifold. Torque curve and max torque is good and timing at 14 degrees with normal unleaded
Thanks for that Richard, that’s quite interesting! I see yours has the trademark MX-5 “hump” on the torque curve - something to do with the air chamber i believe? I’ve read about it online i’m sure.
Mine doesn’t appear to conform to the normal figures you would reasonably expect to see, i’m waiting to have a Mazdaspeed 4-2-1 manifold put on so that might help things hopefully. I have a Milltek stainless exhaust, de-cat pipe and K&N filter already - the only other things i would possibly do (without going FI) would be to get an ITG Maxogen induction kit and use a MS PNP / EMB to tune the car up to try and exploit the most i could out of it with the mods i’ve got.
At the moment i’m waiting on the delivery of a timing gun so that i can check for myself what the timing is currently set to, i have located the two notches in the crankshaft pulley so it’s definitely not a 95’ engine with just the one mark and it should be fairly easy to check where the timing is, and if need be, change it by lining up the right-hand mark with TDC and the left hand mark with 10 degrees.