correct answer

 

Drove it today and it seems to be smoking less than it was this morning. Maybe it just holds compression better when it is warm. Seems to run normal and still makes tons of power, perhaps I can get away with new Mazda valve guide seals. I doubt it though, most likely just too much boost for such an old motor.

I better heed the words of the prophet 18psi.
Somehow I don't think this motor will make it to 250k.

 

Looks like my motor is toast

I will keep it running for a few more days as my friend is visiting from the Carolinas and he's dying to go for a ride. But I can only drive at night with it oil burning around here.

After that I will order some connecting rods from Savington, because I like him, he is honest and stuff in California shows up very quickly.

I wonder if anyone has a suggestion for rings as I will be using polished stock 8.8:1 pistons for this build. My plan is to run Mazda rings and valve stem seals. Sometimes there is a cool guy at the local Mazda parts counter who gives me a deal. However I am open to alternatives.

I also plan to build the current block as well but I don't have any pistons. Wondering what low compression pistons will do to emissions. Maybe I should just get supertech pistons in the correct compression ratio for the original block. Yes I will use nice H beam rods as well, but for sure this motor will need to be bored.

I guess on the bright side, no need to buy a high dollar bp4w head core, I can just use the one on my motor

 

Do yourself a favor and use quality forged pistons. They will come with the right rings, and all you need to worry about is how they will be gapped. Personally, I prefer a bit more compression than 8.6:1 to get a crisper off boost response, but I'm not the forced induction guru either.

 

Unless you are running pure e85 or race gas, then 8.6:1 Supertech pistons are always the answer in a miata motor. Miata's love timing and anything above 8.6:1 limits the amount of timing you can run at higher boost levels. He even has to live with crappy 91 octane at best. So no way should Carlos be chancing it with higher compression pistons.

 

I mean, he IS in the Bay Area, he DOES have access to E85

Give Andrew a call. Seriously. He can answer your questions and point you in a solid direction re: piston choice.

 

I will run the 8.8:1 pistons with sealed power rings unless I decide they don't measure to spec. Then I will have to get the 8.6:1 supertechs from Andrew.

E85 is across a bridge either way which easily knocks 50 miles off my range round trip. Unless that changes soon, I am planning to run low compression. I have read Andrew post enough times to know not to consider anything else for CA91. I might consider stock compression pistons for my clone motor though

Cleaning up the garage a bit and I want to do a couple of routine maintenance things to my truck and my wife's car before I get started. The car still runs great, so I will keep it able to move on it's own power until I finish the bottom end. I will keep you guys updated.

 

I see, you are going to run all BIG boost on us. Uh Huh.

 

You got it correct. Stick to the lowest compression pistons you can get. CA91 sucks *** from what i hear.

 

So let me add another voice to what you have heard.
Yes CA "crap camel ****" 91 sucks! I can't run more than 14° up top. A couple times I even got a crap tank that set off my knock retard like crazy for 2 tanks. I would literally think I broke something only to see in my log that my timing was knocked back to like 10°.

Seriously I had to run a whole nother tank through before I would stop getting knock.

I even considered trying this or draining my tank the second time.

A guy at the track swore he could run more timing with it, although I am not a fan of these sorts of things. What can I say, when I am running slow, with a new full tank, and getting tons of knock. I tend to get a bit panicky and consider **** I normally wouldn't.

Aww heck, maybe I should just throw some 12.5:1's in there, a couple of giant cams, all that head and valve train work so I could go all NA on you guys. Then I could use my stagnant account on that other Miata forum, maybe they would accept me then
I don't have enough stance for those guys anyway.

 

Have you considering running a few gallons of race fuel when you go to the track?

 

Have thought about it a couple times, trouble is I have no tune for a high octane mix. I also usually show up a bit later than I would like so I fill up before hand. I always run a full tank now, it helps my 60' time.
Of course there is this, which thwarted me last time.

Maybe when I have 2 built motors, I will try the GT stuff and ramp it up to 20° to vaporize one of my 5 speeds.

Plus I wanted to see what I could achieve on pump CA with all seasons.
Looking back I made over 140 1/4 mile passes and put 19K on a motor with over 2 and 1/4 centuries on it. I am totally happy with the outcome so far, lasted way longer than I expected.

 

lower comp won't affect your emissions. since you're still using primarily pump gas that's the way to go. I'd suggest setting up flex fuel but don't think your ms2 can support it.

but for the track, make a e85 tune and use that. trust me, it's very worth it (I'm also assuming you have injectors for it too).
you're gonna hit a ceiling with 91 really fast, even with a built block.

 

Thanks, I thought we had talked about that before but I couldn't remember for sure.

I will need a set of ID's to run e85. IIRC my injector duty cycle is above 80% at the top.

Checking my settings in a few minutes to see about flex fuel for the future. I do trust you Vlad.
18psi
Good seller
Good advice
Better listen to what he says!

Maybe if I can remember how to log on to the rx7 site, I can sell some rotary stuff to fund MS3 + injectors. Maybe I should just make a sonofthehill account there. At some point, anyway...

 

What about adding a few gallons of race gasoline in pump gas? My understanding is you don't need to make fuel enrichment changes, and it gives you an added level of safety when you are beating on it at the track. You just can't get greedy with timing.

 

If I can get off work early enough to maybe I can do 3/4 91 1/4 100.

 

You guys are not going to believe this. My plugs look good, I put them in when I first installed the turbo 19K ago. I started the car and no smoke, then a short while later, clouds. Turns out I am leaking oil from the turbine, out the downpipe.

I am not having good luck with these medium turbos, on the other hand, my motor is fine

 

Don't worry I listen to 18psi.
I am going ahead with the motor build anyway.

 

Well that is shitty that the middle turbo died again. At least they are cheap as **** to replace. Or buy a new one, wait a month, and return it under "warranty" with the broken one.

 

I did something similar, it works.

Alternative: Pay for shipping on the turbo i just dyno'd with and get it free!

I'll be swapping it this week with the original mkturbo, new plans.