MBSP - Big deal or not?
 

I am in the middle of an engine build on a '99 motor so I do not have the MBSP and corresponding oil pan. I am shopping for one now but not having any luck so far finding one at a price I can afford.

I am building an otherwise stout bottom end (forged rods, ARP studs, etc) and am wondering if getting the MBSP is really that big a deal or not, like worth $300+. I have read a few threads here and on m.n but did not see anything conclusive.

MBSP? They're useless.

Seriously. After making 1.8l Miata motors for six years, Mazda decided to add the MBSP for no reason except that they just wanted to add parts to make the engine cost more to manufacture.

Here's my opinion after seeing this MBSP in person. It's a piece of sheet metal. I thought it was a cast iron gurdle or something like what any ready setup would have. IE-I've seen toyota motors where all the main bearing caps are all one big piece of cast iront that's machined to bolt down.

I can't really see it doing anything for main bearing rigidity. Besides, it's not like the main bearings are weak. Not by any means. There's only one reason I can possibly think of that the MBSP might actually be worth something. And that's it keeping the caps from ever resonating with the crank as to increase crank flex. No idea if this is the true reason it was used or not.

Oh yea, FWIW, 95-97 kia Sephia's have a BP 1.8 w/ forged crank and a MBSP. You'll need to modify your 99' pan or get an 01 pan though and pickup tube for a 1.8 miata.

Ive got one in my 94 bottom end :)

I probably woudlnt have bought it if it didnt come with my motor thoe.

I talked with someone at FM about this while I was calling around looking for one. He thinks it is overkill for my anticipated power level, less than 300 HP. He mentioned a customer that was successfully running a 600 HP Miata engine without one. They did have a MBSP but not an oil pan. I know the non-MBSP pan can be modified but from what I have read it is a PIA.

The MBSP itself is not that expensive. It is the oil pan that make it pricey. I think I am going to pass on it.

Thanks for the replies.

theres one on clubprotege.com for 45 bucks righit now in the classifieds, im not aware that the oil pan needs to be modified but then again all my stuff is fwd