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Does anyone know what modifications can be done to the cylinder heads on a 94 mx-3 DOHC 4 cylinder 1.6? I mean besides port matching and polishing.
I know most American cars get upgraded valves and larger valves. I would like to do some power upgrades starting with basic engine mods.
I know American cars install 2.02 intake and 1.60 exhaust valves.
I wanted to install titanium valves, but I also want to install larger valves and better springs.
Has anyone does this? If not is there anywhere I can go to get this info?
Also, how large can the block be bored if any.
Any info would be greatly appreciated.
Thanks a bunch.
This forum has been a great help and a major inspiration for me.
Thanks a lot.

Some of this information can be dug up threw searches I know someone had a good na info thread a while ago.

Although the best source of info about the bottom half of the block would ocme from mitat websites on the b6.

Most people tend not to play with the valves and just go for turbo

Previous inquiries into the valves revealed that they are rahter large for the size engine, so nobody really messes with them. Beter performance can be had by changing out the cams though. Toda racing has a wide variety of grinds that can be used for wilder engines, but you can also mix & match some of the other available cams to get good increase in power w/o sacrificing your ability to pay rent or buy food.

As far as porting the head, you can always do more, but that is better left to a professional with a good knowledge of whats what & a flow bench to match up the numbers. Usualy best to have the intake AND the head ported & flowed at the same time.
While the head is getting redone you can get them fly-cut it & up the compression, using the thin high pressure head gasket it's possible to get 12:1, but 11:1 is more managable. In either event you'd need a good knock sensor to control detonation. Can always run race gas, but the cost to drive it,...

You can take the B6 block out another 3mm on the pistons, will make it into a 1.7L & add some more grunt. Not recommended for a car you intend to actualy drive every day. Again, Toda racing has a kit for about $900, pretty spendy for some pistons. There are other parts that can be used that dont cost near as much, stock MR2 Mk1 pistons work & are very affordable.

I pushed up my topic that has all the info I looked up. More details can be had there, but the Miata forum is the best place to go for definitive answers to upgrading the B6.

Thank you very much for the info. I is really going to help out. One more thing, do you think installing titanium valves would help? Let me know your thoughts.
Is it feasible to install a turbo on this motor or not.
Thanks a lot!!

Titanium valves help for the bragging rights. They wont give you better flow or anything, thats all in the porting & cam geometry. A good set of stainless valves will do the job just as well w/o killing your finances.

As for turbo, I've been told the B6 is an excellent base for a turbo, hence the B6T. Could probably get the guts from a B6T, or have something custom made.

oh, so a B6T is a B6 with different internals and a turbo setup?

yep, you can order them from corksport.com

the only difference in block internals is the pistons. our B6 is 9:1 and the B6T is like 7.9:1 or some where around there. your best bet in valves is to get a 3 angle valve job. this will give you alot better flow. if you get a bigger valve size you will also gain. but you should port and polish like someone already said.

Originally posted by Josh:
the only difference in block internals is the pistons. our B6 is 9:1 and the B6T is like 7.9:1 or some where around there. your best bet in valves is to get a 3 angle valve job. this will give you alot better flow. if you get a bigger valve size you will also gain. but you should port and polish like someone already said.

The rods were also different.

<img src="http://members.aol.com/solomiata/gtxrod.jpg" alt=" - " />

Originally posted by jaydog5678:

Originally posted by Josh:
the only difference in block internals is the pistons. our B6 is 9:1 and the B6T is like 7.9:1 or some where around there. your best bet in valves is to get a 3 angle valve job. this will give you alot better flow. if you get a bigger valve size you will also gain. but you should port and polish like someone already said.

The rods were also different.

<img src="http://members.aol.com/solomiata/gtxrod.jpg" alt=" - " />

i new they were different. but MAZDA is now using the same rods in replacement parts supposidly. they no longer sell the the B6T turbo rods like that, they are selling the same ones that come out of our B6 for the B6T. now this is what i was told by MAZDA and several people on the board. they werent selling enough or something, and our rods are supposed to be almost as durable.

I hate to rehash on old thread, but.........
Freq2002,
Would it be ok to get the head fly-cut and not use a thin head gasket? Could I get away with that and not use a knock sensor?

That all depends on how high you take your compression ratio & what gas you run. Even with the stock gasket, shaving some off the head will raise the compression. As the B6 is already pretty fair on C/R there's not too much to play with. A minor cut shouldn't affect it too much though.

Without making it a high compression monster, the best thing you can do without swapping parts is porting. If you have the time while the engine is apart anyway.
This link is pretty informative on the subject altho they plug thier products pretty heavily: Porting