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Wondering what brand of valve springs would be best for a NB8A head running bucket loads of boost?

Realising that the motor isn't going past a stock redline, so float isn't a problem, however sealing the inlets at 28lb is boarderline for stock springs.

Not all that much aftermarket support for springs and usually the replacements have similar load ratings just with Titanium retainers to reduce recipricol mass.

I'm sure some of the racers will be able to suggest a suitable upgrade.

Cheers

I've always used the Flyin Miata upgrade which I think are speedtech items. Very reliable at 8500rpm..... There are other available too - maybe ferrea or manley do some too from memory. Toda should also be on your shopping list - pricey though.

Thanks CT
I'd seen the FM and Toda but neither of them list specifications . Amongst the drag racers Ferrea doesn't have the best of reputations, so that leaves the Manleys. I'll look into them and keep you all posted.

Cheers again
Wòó

Not sure how you work that out?

Increased pressure on the seat of the inlet valve from 2 bar of boost will lift the inlet valve off it's seat whilst the cylinder is on it's exhaust stroke. This will cause the valve to slam shut (stretching the stem and damaging the seat).

BTW, non std Cams, valves, and already spent $13k so whats a bit more for the performance gains?

I've gone for the FM units with Titanium retainers and spacers. I'm also using their OS valves. Cheers CT

Good bye non- interference motor .... putting a lot of faith in the Gates belt (T179R)

Wòó

It's not a street car, it's built for quarters.

To top the class you require that the engine number matches the original (and also be the same block, so no re-stamps).

It's all very well, and full cred from me to the rotary guys, to throw a 13 or 20B in and have no torque but then it ceases to be an MX5 imho and becomes a homologation.

The aftermarket support is out there.... you just have to look for it, and it's inexpensive!!!. The JDM MX5 scene is as big, if not bigger than the Niz scene, and anyway any tool can hot up a Nizzy (no offence ment ;) ).

The object is to be top of the class. 450 kW at the fly and sub 10's.
Built properly (as this one is shaping to be) will last a good 10000 k's before a re-build, so I'm happy

Compare an S15 short motor price to a low klm BP and I think you'll find that the BP stacks up very favorably.

If your worried about $$$'s in this game .... maybe you shouldn't be in it. kW for $$ the BP's are reasonable, not the best but far from the worst. Try v8's and 10's and then you realise how inefficient and costly a motor can be.

Wòó

Woo wrote:It's not a street car, it's built for quarters.

To top the class you require that the engine number matches the original (and also be the same block, so no re-stamps).

What class is that? ANDRA rules? Doesn't seem familar to me?

Hey Sean, correct, that isn't an ANDRA ruling, it's an AHRC judging guideline thats been around for 3 decades.
It was implemented in the 70's to stop/deter people building structurally unsound rods.