Engine Build - Not sure if it will be NA or Turbo!

[daffyflyer]

Better add a computer to that list....

Oh, forgot to mention that, Already have a Wolf3d

[Matty]

You'll need a custom head gasket if going >1.5mm overbore.

[CT]

I think you are about to get a rude shock as to how much building a decent specced up motor might cost. As Matty said, anything over 1.5mm overbore requires a very expensive TODA head gasket - they are the only ones in the world that make them. They are at least $500 each. Secondly, the 805c cam would be wasted in a full on 11:1 comp motor - that is a street cam designed for a stock ECU. Then, if you go to a bigger cam, you must use shim under bucket lifters otherwise the shims will be wiped off the lifters and you will never get the lift the cams actually need to work. Then, your head will need to be modified to actually deal with the increased lift as the cam lobes will hit the head castings. Then , you will need better springs as the stock ones won't fit. Changing valves in an NA motor won't really do anything except empty your wallet. With a bigger cam, you really need a proper, flow benched head port otherwise your cam will start the motor of air. Big cams need bigger revs to really work, so you need lighter rods and pistons at least. The Wiseco 11:1 pistons are great - I highly recommend them but only buy them from Flyin Miata - the local catalog Wiseco piston is different from the FM ones - they have a slightly different crown and skirt design.

So you see where this is going. My advice....

Get another stocky engine, pull the head, take 20thou of it. Keep the 805C cams and use 11:1 pistons in a 1mm overbore if you can get someone to make them with stock rods and new rod bolts (Carillo A beams are awesome if you can afford them) - (ACL might do a 10:1 piston from memory). Get the head a mild port and perhaps 5 angle valve grind and then bolt it back in the car. Cost is lower, the engine will be sensible and reliable and you can use mazda head gasket kits, bearings and spare parts. You should still get upwards of 95rwkw except the engine will be drivable and not an experiment in wallet emptying. High revs and higher comp means less reliability and more $$$. everytime.

[daffyflyer]

Cheers CT, I was hoping someone who actually knew about this would comment!

If i understand you correctly, what you are thinking is similar to what im thinking but a 1mm overbore?

So:

Fresh motor (either another, or a rebuild of my own with stock parts)
With: Wiseco 11:1 Pistons +1mm
805c Cams
Mild Port Work
New Rod Bolts.

Yes? - Sounds like a good plan to me (and pretty close to what i was thinking anyway)

Also, why do you suggest another stock motor, I would think that would cost more than fixing the bearing damage, and could be quite tired anyway?

[wun911]

whoa sounds like a lot of work, please post pics if you do go though with it sounds interesting.

otherwise I assume turbo is cheaper bang for buck?

[daffyflyer]

otherwise I assume turbo is cheaper bang for buck?

Always is

Keen to not go turbo though, Don't really need that much power, want to stay in < 2000cc class hillclimbing, and the engine needs a rebuild anyway so i may as well throw some scary sh*t at it
Oh, and im hoping it wont be too much of a defect magnet

[Fuzzlet]

Keen to not go turbo though, Don't really need that much power, want to stay in < 2000cc class hillclimbing, and the engine needs a rebuild anyway so i may as well throw some scary sh*t at it
Oh, and im hoping it wont be too much of a defect magnet

What the cops cant see, they cant defect you for haha

[daffyflyer]

Keen to not go turbo though, Don't really need that much power, want to stay in < 2000cc class hillclimbing, and the engine needs a rebuild anyway so i may as well throw some scary sh*t at it
Oh, and im hoping it wont be too much of a defect magnet

What the cops cant see, they cant defect you for haha

Unless old mr copper has a compression gauge he'll be none the wiser

[manga_blue]

Get another stocky engine, pull the head, take 20thou of it ...

Whoa Chris, I'm doing an NA8 rebuild at the moment - stock with a bit of a tidy-up basically. I've got about 5 thou of head warp and 2 thou in the block so I was thinking about taking 6 thou off each to straighten it all up. Mazda specify 4 thou max off the head and 10 off the block yet you're saying 20 thou is doable in the head alone.

I'd rather listen to you than Mazda. How much do you think is a really good safe limit for a road/clubsprint car?

cheers

[Fabio]

If you have spun the big end bearing in the conrod, then I would be replacing it also, as the heat generated from the spun bearing can cause the rod to go soft. I have seen rod bearings that have failed, and the conrod and crank were throw away items. You won't be able to tell what condition yours is in until you pull the engine down. If this is your first venture into the internals of an engine, I would suggest you keep your goals relativly simple and follow the tried and true path. I like CT's advise, it sound realistic, and doable on your budget. I would not suggest however, that you build it yourself, if it is only going to be a once in a life time thing. There are too many tools and equipment that you will need to do a top quality job, that you will never be able to use any where else (some you will be able to use elsewhere). If however you plan on rebuilding other engines, I would say go for it. There are some exellent books available, that give great instruction on rebuilding and blueprinting engines. Go have a read before you decide on doing anything. Even if you decide to have someone else do the job, at least then you will know what your talking about, and be adle to communicate clearly what you want to your engine guy. You will also have a better idea if you think you being ripped off or getting a good deal.

[CT]

Get another stocky engine, pull the head, take 20thou of it ...

Whoa Chris, I'm doing an NA8 rebuild at the moment - stock with a bit of a tidy-up basically. I've got about 5 thou of head warp and 2 thou in the block so I was thinking about taking 6 thou off each to straighten it all up. Mazda specify 4 thou max off the head and 10 off the block yet you're saying 20 thou is doable in the head alone.

I'd rather listen to you than Mazda. How much do you think is a really good safe limit for a road/clubsprint car?

cheers

Mazda are very conservative when it comes to tolerances - that I can understand. I would recommend getting an experienced machinist to skim the head and deck the block. The last head I went nuts on had a 40 thou skim - which was extreme, but the block also had a 20 thou deck. This raised comp by another ~.7. The wisecos in 11:1 are only available in a 2mm overbore last time I bought them - you might need to go elsewhere. I will check on the 40thou though - I am positive we took 40 off the head......unless it was 40 in total.....damn memory......I'll check.

Something to remember about the thermal effeciency of an engine, more material in the head and block actually helps cooling. It is not uncommon for highly modified engines to run hotter. In winter it's not an issue but in summer it can be so don't rule out bigger radiators and coolant reroutes if you get to the extremes as I have mentioned.

Also, please study the SoloMX5 website of Randy Stocker in the states. He and a few of the US guys have built motors like my old one and Randy knows his stuff. Get on miata.net and research.

[daffyflyer]

I would not suggest however, that you build it yourself, if it is only going to be a once in a life time thing. There are too many tools and equipment that you will need to do a top quality job

Nope, not going to be a once in a lifetime (The lancer motor could do with a freshen up after this for one!),
and i will be using a mates shed full o' tool goodness (might need to buy a good torque wrench and some feeler gauges though)



Found a good price on some 11:1 pistons and H beam rods through Carco... oh so tempted...

[93_Clubman]

Get another stocky engine, pull the head, take 20 thou off it.

Whoa Chris, I'm doing an NA8 rebuild at the moment - stock with a bit of a tidy-up basically. I've got about 5 thou of head warp and 2 thou in the block so I was thinking about taking 6 thou off each to straighten it all up. Mazda specify 4 thou max off the head and 10 off the block yet you're saying 20 thou is doable in the head alone.

I'd rather listen to you than Mazda. How much do you think is a really good safe limit for a road/clubsprint car?

Tanner in Mazda Miata MX5 Performance Projects says "between 0.010 inch & 0.020 inch (0.25mm to 0.5mm) is a good range" on a head.

[daffyflyer]

Oh, and just to get things clear CT, are you talking about 11:1 pistons PLUS 20 thou off the head? If so, isn't that a lot of compression? (not that i mind, if it will run on 98)

[CT]

Regardless of the head shave, you should run 98 and have it tuned that way. Just be careful about the oversize of the wisecos - most are 2mm which will cause you more cost re head gasket. Also, the locally delivered wiseco's are different and in my opinion slightly inferior in design to the ones from Flyin Miata which are not available from the catalog. Try ACL or Arias to see what they have. A better idea is to speak with Gary Stewart who builds lots of the QLD 2F engines...he might have them on his shelf. Forget H beams, most turbo's don't even need them.