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Post by paultb on Oct 19, 2016 9:53:11 GMT
My MP62 supercharged Mk2.5 1.8 Sport is currently having its engine rebuilt due to bent conrods. I'm wondering if it's worth doing cam reprofile at the same time, what do you think? What sort of power increase would I see and what else do I need to do?
The engine is being done by Skuzzle and the car is currently running 208 whp (well, had been until it blown). It has BRP MP62 charger with a bigger nose pulley (can't remember the size), intercooler, MS3 ECU, Bosch EV14 injectors (520 iirc)
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Post by Horney on Oct 19, 2016 10:01:45 GMT
They showed good gains on Kraigys 1.6 M45 equipped car. It's not something that's really been done much though so you'd be a trail blazer.
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Post by paultb on Oct 19, 2016 10:29:34 GMT
I'm fighting with myself now, on one hand I don't want to spend any more money on the car, just fix it and enjoy driving it, but on the other hand if I can get some significant power gain at relatively low cost, especially now that the engine is stripped anyway, then why not? What sort of gain did the 1.6 M45 achieve?
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Post by Horney on Oct 19, 2016 10:37:29 GMT
20whp. That's a chunk and like you say you have the engine in bits so extra cost is pretty much the cams and shims only. Do it!
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Post by josho on Oct 19, 2016 12:19:13 GMT
If you're wondering about it you already want to do it  Cam regrinding on standards will give moar lift which means more air in and out so more room for tunings. In the words of good old mr LaBouef Just do it! |
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Post by BikeTuna on Oct 20, 2016 7:16:42 GMT
Sorry to go slightly off topic, but where do you get the MP62 mounting kit? I cant find one...
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Post by Vindi (Russell) on Oct 21, 2016 0:27:26 GMT
Sorry to go slightly off topic, but where do you get the MP62 mounting kit? I cant find one... He said it was a BRP kit, they aren't made any more. It's a full kit with a purpose designed charger body. I wouldn't bother with cams, it's a lot of money for little gain when compared to a bolt on crank overlay pulley that could get you a lot more gain for about £100 and negligible fitting costs I'm assuming you mean smaller nose pulley? Russell |
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Post by Horney on Oct 21, 2016 7:47:23 GMT
Sorry to go slightly off topic, but where do you get the MP62 mounting kit? I cant find one... He said it was a BRP kit, they aren't made any more. It's a full kit with a purpose designed charger body. I wouldn't bother with cams, it's a lot of money for little gain when compared to a bolt on crank overlay pulley that could get you a lot more gain for about £100 and negligible fitting costs I'm assuming you mean smaller nose pulley? Russell I would say 30bhp at the flywheel is more than a little gain. |
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Post by Vindi (Russell) on Oct 21, 2016 9:02:16 GMT
He said it was a BRP kit, they aren't made any more. It's a full kit with a purpose designed charger body. I wouldn't bother with cams, it's a lot of money for little gain when compared to a bolt on crank overlay pulley that could get you a lot more gain for about £100 and negligible fitting costs I'm assuming you mean smaller nose pulley? Russell I would say 30bhp at the flywheel is more than a little gain. As I said, compared to a crank overlay it's a lot of money for little gain. The mapping costs are the same for either, the cams will cost maybe £400, plus whatever for faffing around with the shims and fitting them and retiming everything, plus do you need vernier pulleys to get the most out of them?. Probably £6 - 800 when all is in and fitted? Crank overlay is about £200 fitted and will give a bigger gain, depending on the size of overlay you go for. Russell |
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Post by Horney on Oct 21, 2016 9:22:03 GMT
His engine is already in bits though. Now she time to do it and add a crank overlay later.
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Post by myothercarsa2cv on Oct 21, 2016 11:12:00 GMT
I'd be very interested in how the regrind works out, I'm already spinning the charger as fast as I dare!
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Post by Vindi (Russell) on Oct 21, 2016 14:10:27 GMT
His engine is already in bits though. Now she time to do it and add a crank overlay later. Why take apart something that works fine (the head) and why pay the extra money out at all? The crank overlay will already take you right to the edge of what an MX5 engine will take. Don't get me wrong, cams sound cool and interesting etc but if the nose pulley has already been done then a crank overlay will get you to anywhere from 240 to 280 depending on the size. Adding cams to that is pointless if you're not throwing another £1k + at forged parts, uprated oil pump etc etc Russell |
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Post by Horney on Oct 21, 2016 14:33:21 GMT
He is having forged rods though as they bent.
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Post by Vindi (Russell) on Oct 21, 2016 18:54:04 GMT
He is having forged rods though as they bent. That's a good start, although there are other weak points that would need to be addressed if the power got to 300bhp ... which hopefully he is having done as well? Most of the people with MP62 chargers just have mid sized crank overlays, to limit the power to 250bhp. A few have taken it further and seem to get to 270/280 before the charger gets stretched, so I'm guessing the cams being added could take it over 300 ... there's so many unknown factors in there though, I guess it would be a bit of an experiment.
I guess none of this discussion is that useful without knowing what power the OP wants ultimately. If he just wants a bit more power, then changing the cams is not a clever way to get it as it's relatively expensive and complex compared to swapping a crank pulley. If this is just one stage and other changes will be made to get more power again, then I guess now is as good a time as any. Would be interested to know what the difference in cost would be, just having the rods done compared to new cams with whatever else is needed to make them work and the fitting costs that result from it.
Russell.
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le sigh