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Old 06-20-2009, 11:06 AM   #1
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Default all-motor time: extreme mpg daily driver

So my daily driver, ugly, shitbox miata needs a motor...bad. I'm bruning like 1qt every 500 miles, it just feels hurt, and its just fucked. Its a 1994 and I'd like to put 10:1 pistons in it, but I can get Supertech 11:1 84mm slugs from Belfab for $430, run the stock rods, ghetto header it already has, probably won't pay the cash for a 99-head, and John Day will do the machine-work.

Even though I'm looking at buying a Tacoma, I'd love to keep this car and see if I can get 35mpg out of it on the daily commute. It will probably get driven by my sister on the track.

Qeustions:
Can I run 91-octane on 11:1 static comp?
Lots and lots of spark advance, at 16:1 = 35mpg?
Can I road tune NA on a narrow band (down to 12.6:1)with enough effort?
Should I paint it Vette orange?
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Old 06-20-2009, 11:13 AM   #2
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You can indeed run 91 gas with high-compression pistons. Just master the tune as always.
Keep the paint as-is. Everyone needs a filter!
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Old 06-20-2009, 11:17 AM   #3
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if you ****** drive it right your turbo car can get 35 mpg newb. on the stockish car my dad has seen almost 50mpg while hypermiling, on a stock 96 with no cat. Hell ive even done 32 mpg for a few tanks on mine.
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Old 06-20-2009, 11:19 AM   #4
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Originally Posted by juxt3r View Post
You can indeed run 91 gas with high-compression pistons. Just master the tune as always.
Keep the paint as-is. Everyone needs a filter!
of course I could, but can I run enough spark to run it at 16:1 cruise? I have no problem doing that in my turbo car (although at run no leaner than 15.5:1).

A lot of these honda guys are getting 45+mpg by running 17:1 with like 32*advance. I want some of that action. I should not that I also plan on logging EGT with MS.
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Old 06-20-2009, 11:20 AM   #5
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Quote:
Originally Posted by hustler View Post
So my daily driver, ugly, shitbox miata needs a motor...bad. I'm bruning like 1qt every 500 miles, it just feels hurt, and its just fucked. Its a 1994 and I'd like to put 10:1 pistons in it, but I can get Supertech 11:1 84mm slugs from Belfab for $430, run the stock rods, ghetto header it already has, probably won't pay the cash for a 99-head, and John Day will do the machine-work.
Just JBWeld some aluminum inserts on top of your stock pistons. Cheap and easy...

This sounds like a fun build.

Quote:
Originally Posted by hustler View Post

Qeustions:
Can I run 91-octane on 11:1 static comp?
Lots and lots of spark advance, at 16:1 = 35mpg?
Can I road tune NA on a narrow band (down to 12.6:1)with enough effort?
Should I paint it Vette orange?
I'm guessing this is staying with the stock ECU, so I'm not really sure on the first one. I don't think it's a problem, and you can makes some runs with your det can to check it out as you're advancing the timing.

On the timing I imagine 14 degrees static should do the trick. Consider that everyone does this to get more midrange torque N/A, and this is basically your cruising rev range. You should be able to see close to 35mpg.

Paint it whatever suits your fancy...post pics...and we'll have one more color to choose from.
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Old 06-20-2009, 11:21 AM   #6
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Originally Posted by magnamx-5 View Post
if you ****** drive it right your turbo car can get 35 mpg newb. on the stockish car my dad has seen almost 50mpg while hypermiling, on a stock 96 with no cat. Hell ive even done 32 mpg for a few tanks on mine.
I go 80-85mph on the highway and can't really drive it like an adult. I managed 255 miles on my last road-trip. I need to run a cap on the power for my computer though because my logs are still spikey enough to jack with MAP enrichments. Also, I don't like driving the turbo car everyday, nor do I like leaving it outside tha club.
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Old 06-20-2009, 11:22 AM   #7
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oh, I'm definitely going to run MS. I wouldn't have it any other way. At this point I wouldn't even put an intake on a car without real engine management. I agree, it will be cool to build a motor like this on the cheap. Its also not a bad idea considering fuel cost. Make a 40mpg msq and a track msq for my sister, or john, or whoever wants to drive it.

That way people will quit begging me to drive my car. Its also really funny considering the "i'm an instructor" ------s who keep emailing offering to "instruct" at no charge. Yeah dude, you're not going to drive my turbo car.
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Old 06-20-2009, 11:24 AM   #8
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Quote:
Originally Posted by hustler View Post
I should not that I also plan on logging EGT with MS.
Slow typing FTL. Wish I had seen that earlier.

If you're running MS then by all means you can do all of the above. Like was said above, just perfect the tune.

I run 16.5:1 all day long from Houston to College Station. When I was doing this N/A with a hollowed out cat I would consistently see 33mpg. I didn't advance the spark much, and of course had lower compression, but I don't see why you couldn't EXCEED 35mpg, probably considerably so.
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Old 06-20-2009, 11:24 AM   #9
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80-85 mph is fine your not out of our aero drag range. The real problem with gas mileage is brake usage and tire drag. So do not use your breacks at all and do not engine break either caost and try to maintain speed at all times. Its not driving like an adult persa cause most adults are breack riding ************* who couldnt take a corner at 100 mph if there lives depended on it much less do it with out breacking.
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Old 06-20-2009, 11:28 AM   #10
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Originally Posted by magnamx-5 View Post
80-85 mph is fine your not out of our aero drag range. The real problem with gas mileage is brake usage and tire drag. So do not use your breacks at all and do not engine break either caost and try to maintain speed at all times. Its not driving like an adult persa cause most adults are breack riding ************* who couldnt take a corner at 100 mph if there lives depended on it much less do it with out breacking.
wtf are you trying to spell!?!?!?! lol
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Old 06-20-2009, 11:33 AM   #11
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oh, I'm definitely going to run MS. I wouldn't have it any other way. At this point I wouldn't even put an intake on a car without real engine management.
I feel the same way.

I also run 80-85, but I've gotten really good at conserving momentum, which is important when trying to save gas.

I'm very interested to know if the higher compression pistons will give you a return on investment. I'm sure you could hit 35mpg with just a rebuild and MS tuning. Even if those pistons bump you up to 40mpg, driving 12,000miles/year it would still take 4yrs to justify it with current gas prices. I know you're too baller to care, just observing.

What would be fun about this for your intended use is to have a couple of different maps. A hypermiling map, and a track map for your sister. A 140whp N/A Miata would be fun enough, and even cooler when you're getting better gas mileage during the week than most supersports.
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Old 06-20-2009, 11:36 AM   #12
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Atomic Orange Metallic or Old Corvette Orange?
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Old 06-20-2009, 11:40 AM   #13
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Originally Posted by gospeed81 View Post
I feel the same way.

I also run 80-85, but I've gotten really good at conserving momentum, which is important when trying to save gas.

I'm very interested to know if the higher compression pistons will give you a return on investment. I'm sure you could hit 35mpg with just a rebuild and MS tuning. Even if those pistons bump you up to 40mpg, driving 12,000miles/year it would still take 4yrs to justify it with current gas prices. I know you're too baller to care, just observing.

What would be fun about this for your intended use is to have a couple of different maps. A hypermiling map, and a track map for your sister. A 140whp N/A Miata would be fun enough, and even cooler when you're getting better gas mileage during the week than most supersports.
I've driven johnwag's 123whp car with the 4.30 on the track and it was fun...lots of fun. Actually, after my first track event, I almost wish I had gone that route, but more seat time will change that.

I've thought about throwing a stock, fresh motor in it for roughly $500, but why not just spend a couple grand to make the car a lot more fun...and have a motor worthy of the effort and time with the wrenches.
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Old 06-20-2009, 11:45 AM   #14
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wtf are you trying to spell!?!?!?! lol
whatever man you can **** off then if you dont want any help you can kiss my ***. Go spend your ****** millions on bullshit.
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Old 06-20-2009, 11:47 AM   #15
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True enough...I've often wondered myself what I missed in that middle ground between 93-200whp of exploring the Miata's nuances. I originally planned to start at 5-6psi and work my way up since I've always loved driving the snot out of this car, and just thought it needed a *little bit more.

Instead I adjusted the wastegate actuator the wrong way, and there's no going back from 10psi. Now I'm constantly trying different suspension setups, upgrading brake components and adding chassis stiffeners to try and get back the the balance I felt this car had in the decade we drove it underpowered. I think what you want to do will complement the car more than upsetting it.
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Old 06-20-2009, 11:52 AM   #16
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I can run my turbo 10:1 car at 16:1 AFR if I want. the issue at cruise isn't detonation so much as it is misfire from the leanness. 91 shouldn't be an issue. but you may not get as much advance as you want--though I'm not sure why you want it so far advanced. just balance AFR, EGT, and advance so you're not melting valves and push it as lean as you can.

how about some N/A water injection??
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Old 06-20-2009, 01:37 PM   #17
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long duration and heavily retarded intake cam = lots of mpg
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Old 06-20-2009, 03:09 PM   #18
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whatever man you can **** off then if you dont want any help you can kiss my ***. Go spend your ****** millions on bullshit.
relax dude. Try to lol. Go out to the barn, pour a little mule kick, and get down with some bovine intimacy.
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Old 06-20-2009, 03:56 PM   #19
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How about you buy a new MP3 player first?
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Old 06-20-2009, 04:16 PM   #20
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How about you buy a new MP3 player first?
just did, fuckface.
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