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Old 07-26-2015, 01:35 AM   #1
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Default wheres the weak point

attempting to put together a built motor for a miata

I am having some problems figuring out where the weak point is at what power levels ect of different components.

I found a great deal on some supertech pistons and manly h beam rods along with some arp head/main studs and picked it up. Pretty poverty rods and pistons but it was so cheap it was worth blowing apart and at least getting some shake down pulls/driving on before XXX blows apart.


What would be the weak spot in that setup? When is the crank a issue ect.
I have done a bit of searching but at most you find a couple people say yeah that should hold 350whp fine...but you never see or hear about bigger hp builds that are out in the open or at least that i could come across.

I plan on making a bit of power ie 58-62mm turbo as it is just a project car as i make the sti more tame for daily duties vs its old 68mm turbo setup.
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Old 07-26-2015, 01:46 AM   #2
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<p>Transmission blows pretty regularly at 350. So there isn't much experience above that power level.</p><p>There is a thread somewhere where this is all discussed. Search plz.</p>
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Old 07-26-2015, 01:48 AM   #3
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<p>Transmission blows pretty regularly at 350. So there isn't much experience above that power level.</p><p>There is a thread somewhere where this is all discussed. Search plz.</p>
I already said above i have been searching for a while now and havent really came across much info on higher hp builds.

If you would like to link me to that thread id gladly take a look and let this one die off until then all i can do is keep searching random search terms hopping something comes up besides that one s366 build and wait for some answers on here.
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Old 07-26-2015, 01:52 AM   #4
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<p>https://www.miataturbo.net/general-m...ts-part-81560/</p><p>There ya go.</p><p>Manly and supertech is far from poverty. A lot of people run ebay rods and stock pistons.</p><p>Stock pistons are good to the same level the 6 speed is if you don't detonate. A lot less if you have det.</p>
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Old 07-26-2015, 01:53 AM   #5
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<p>Those are just guidelines. For example, I recently blew a transmission at &lt;200ft/lbs. But I drive like an ***.</p>
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Old 07-26-2015, 02:05 AM   #6
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<p>Those are just guidelines. For example, I recently blew a transmission at &lt;200ft/lbs. But I drive like an ***.</p>
Thank you!
Some pretty good info there i will be shifting through it now


and i know that manly h beams are not poverty by anymeans but i guess i just have that view because the platform i come from they are not much stronger then a stock rod so i have always viewed them as pointless

I also saw some post saying that the supertech pistons melt? (i assume poor tuning is at fault)
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Old 07-26-2015, 02:08 AM   #7
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Our stock rods are cast. So they are junk. Supertech pistons are fine for 90% of builds because once again. Trans.
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Old 07-26-2015, 02:25 AM   #8
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Your setup should work for 350-400. throw in a billet pump and you'll be 400+ capable. once you exceed that, the parts you break will really be just a matter of how the car will be used. this is not a 3500lb sti, so really not a whole lot of power is needed to go fast, and even more importantly: to feel fast. a 400-450 miata is nuts. a buddy's 450+ trapped 132 but more importantly, is a complete nightmare to drive fast. all over the road....you just feel like you're gonna die every time you drive it. nowhere even near the feeling of an awd subaru. that's why you don't see that many really high hp miata's.
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Old 07-26-2015, 02:39 AM   #9
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Your setup should work for 350-400. throw in a billet pump and you'll be 400+ capable. once you exceed that, the parts you break will really be just a matter of how the car will be used. this is not a 3500lb sti, so really not a whole lot of power is needed to go fast, and even more importantly: to feel fast. a 400-450 miata is nuts. a buddy's 450+ trapped 132 but more importantly, is a complete nightmare to drive fast. all over the road....you just feel like you're gonna die every time you drive it. nowhere even near the feeling of an awd subaru. that's why you don't see that many really high hp miata's.
I saw that fab9 had a nice oil pump looks like that will be a good investment.

Id like to see 13X mph traps as a end game as that was my goal with the sti until i did it and it got extremely boring at which point i went for 14X traps. It never felt super sketchy other then the normal crab walking and wishy washing wot pulling side to side due to drag radials. I could see a miata being much much more skethcy and requiring alot more seat time at higher hp levels.

Seems that the transmission is going to be my biggest issue and it will be time to maybe look into what other tranmissions people are using as a work around.

Thank you guys ill keep doing searches and picking up information also i dont want to be that person just sometimes search terms do not give me what i want haha.

That s366 build i tried reading was like 9000 pages long and i cant even find the spot where it blows up and what failed unfortunately.
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Old 07-26-2015, 02:44 AM   #10
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Don't even read that thread lol
FaeFae is great entertainment and a perfect example of what not to do.

The drivetrain/transmission struggle is real: there still isn't anything that's cheap, and easy, and practical.

My buddy shifted hard into 6th at his power level and twisted the trans output shaft clean off. LOL
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Old 07-26-2015, 02:51 AM   #11
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Don't even read that thread lol
FaeFae is great entertainment and a perfect example of what not to do.

The drivetrain/transmission struggle is real: there still isn't anything that's cheap, and easy, and practical.

My buddy shifted hard into 6th at his power level and twisted the trans output shaft clean off. LOL
Sounds like a supppper bad time lol

I see someone made a adapter plate for a trans from a rx7 at some point in time but the thread died off.

More research is needed thanks again guys!
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Old 07-26-2015, 02:57 AM   #12
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Sounds like a supppper bad time lol

I see someone made a adapter plate for a trans from a rx7 at some point in time but the thread died off.

More research is needed thanks again guys!
If you're interested in the rx7 tii stuff you can take a look in my build thread or mighty mouse's. He's been running his for a while, I still haven't ran mine but all the work for it is done
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Old 07-26-2015, 10:52 AM   #13
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If you're interested in the rx7 tii stuff you can take a look in my build thread or mighty mouse's. He's been running his for a while, I still haven't ran mine but all the work for it is done
Will do
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Old 07-26-2015, 12:33 PM   #14
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If you're seriously shooting for +400whp and +130 trap speeds you should really consider an LS swap. There are several kits, and it's been done a bunch of times.

Up to around 350whp most stock stuff is pretty solid; 6 speed, torsen, axles, and a mildly built motor handle it pretty well. Once you go much beyond that, especially drag racing, you're going to breaking a lot of stuff. At that point a reliable basically stock LS3 starts looking real nice.
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Old 07-26-2015, 12:39 PM   #15
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Then turbo the ls3
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Old 07-26-2015, 04:29 PM   #16
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That was my first choice was to turbo a one of those poverty lq truck motors in the car. I even have a very nice expensive 68mm turbo laying around that would work great for a 7-800whp setup which is doable on a bone stock lq.
But all in it seemed that the price would farrrr outweighed what I wanted and I would gain so much weight it wasn't worth it. A built ls1/2/3 motor to handle a fair amount of power was like 7-8 grand then you have the expensive transmission that still needed to be built ect ect. A lot of my friends have built ls motors 1/3/7 and it made me want to go that route till I really sat down and looked at everything. It would be far cheaper to just buy a used c5 vette with higher miles and just work with that vs swapping stuff into a Miata or building another sb for the sti and shooting for 800whp ish again.

I like the idea of building the 1.8 a lot more....
These motors/cars are dirt cheap to build compared to my Subaru so the lack of sticker shock is great. I also like the challenge I don't mind blowing up a couple motors/transmissions it is just going to be a car that I am building to leave blown up.

Car isn't 100% for drag racing I just like to use trap speeds as a basis of how muchish power the car is making more then actually going to the track. Mostly just roll racing (inb4 everyone calls me gay) or driving around in circles on the weekend and enjoying the car.

Either way for now mind is set on a 1.8L build and just want to gather as much info as possible to get it done earlier then later. I will be starting a build thread sometime today I just finished breaking down my new used longbock I purchased so I could build it on the side to swap in all at once rather then pull the old motor then rebuild that.
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