magnamx-5

iTrader: (7)

Yep you got it given some premo rings forged pistons/rods and billet oil pump gears you will never make to much hp for the motor. Given a good tune. But as i said before the motor should last 15 or so K at 300 i would call that stable.

patsmx5

iTrader: (16)

I hear what your saying Richard, but for some reason my **** dosn't last as long as most people's. Don't know why. I suppose it could possibly have something to do with my driving habits. I drive around 15K a year, so if it lasted that lone, I guess I'd be pretty happy and wouldn't mind spending the money to rebuild it better. How long would it take 300 + a 100 shot for special ocassions?

magnamx-5

iTrader: (7)

IF you drive as hard as i do then you could most likely wear it out in 10-12K you will most likely go through several 5 speeds at that power level as well. They don't like more than 250 lb/ft. Also while it is down if it does go down a cryo treatment and rx7 lsd conversion would be a good investment. The ring and pinions are pretty strong for most apps but torsens dont like alot of torque either. And rx7 lsds can be had for aroun 200$ used or rebuilt.

patsmx5

iTrader: (16)

There's an idea... I'll buy me another 5 speed and send the entire assembled unit to have it cryo treated. Well, that probably wouldn't work, but having the gears and what not inside the tranny cryoed would definately help.

magnamx-5

iTrader: (7)

Well if the gear strenght was the issue it would but it is not case flex pwns us not gear fragility. For instances of that look at the 1.6 dif.

patsmx5

iTrader: (16)

But, FM sells a gear set to upgrade the 5 speeds, not a new case?

neogenesis2004

iTrader: (12)

Its the gear design that makes them break, thats why quaife makes a gear set. I would email quaife about it if you want more factual information about why the trans shreds.

patsmx5

iTrader: (16)

hey neogenesis2004, did you understand that drawing I made? That picture is a rough drawing of how i did my head when I unshrouded the valves. I was saying the dotted line is where the head gasket would seal, since it's a circle. Just wondering what you think.

neogenesis2004

iTrader: (12)

You didnt ever take a picture of the chamber did you? The drawing looks good though, There is a miata head something like that on replika maschinen's gallery. When I was talking about the gasket I was refering to my head and how you said I should have deshrouded my valves more. If I did it anymore my hg lip would be sticking into the cylinder (MAJOR hot spot and gasket damage). Most of the deshrouding you see there is what the machine shop had to do to do the 5 angle valve job. I'd say a good 5mm was taken from the "corner" of the chamber. It comes basically to the edge of the hg.

patsmx5

iTrader: (16)

Nope, no pics at all. I blew a head gasket 3 days before I had to drive my car 260 miles to start college. I wanted to do a lot of head work to it while I had it off. I worked hard and long, and when it was done, it went right back on the car. I'm tempted to pull the damn thing just to take some pics.

Yea, my book I got suggest unshroud 20% for exhaust valves, 25% for intakes. More if the motor will be FI. I did mine by those numbers above. I'm putting a supercharger on, so next time the head comes off, I will probably go 25% on exhaust and around 30 or so on the intakes. Maybe 30 exhaust 35 intakes. Since it's FI, the compression lost isn't as critical. I will absolutely take pics if next time it comes off.