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Old 11-25-2013, 07:14 PM   #1
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Default Connecting Rods

Hi! i don't usually post alot, because i kinda find my answer most of the time!
But know, i can't find any real answer to my question.(Please feel free to link a thread that i could of miss)

So here the question.
I'm bulding my BP4W this winter, I got my head and block checked(Machining will come later on)
I'm pretty decided on pistons, Wiseco 8.5:1(84 or 84.5).
But i got a bit in a dilema when i started looking for rods, but my choice got down to this :
K1(They are described as lighter then most of the other rods)
Manley(Every body seems to be using them, also pretty cheap)
Eagle(They are the heaviest)

I don't want to spend the big cheeze on Carrillo since other rods seems to handle the power output i'm looking for(350-400whp).

Feel free to suggest any other brands too!

Thanks!
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Old 11-25-2013, 08:21 PM   #2
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After doing some research for my engine build, I settled on K1 rods because they are among the lightest of the Tier-2 brands, and

"K1 has also called upon the experts at ARP fasteners to design special K1 proprietary rod bolts with asymmetrical threads to equally load each thread when under pressure. "
(see 89-05 Mazda Miata Connecting Rods: JSC Speed)

Most engine builders here in Australia recommend Carillo rods since they know that they'll never fail in an MX5 since they're rated at >1000hp but all the brands you listed (K1, Manley, Eagle) can handle 600hp which is double what a high-hp MX5 can deliver anyway so the risk is negligible and they're half the price.

PS: You indicated you want about 350-400hp. Are you aware that you'll run into gearbox issues at these levels? The MSM 6-speed tends to crap out above 300hp and the 6-speeds are the toughest factory gearboxes. I intend to limit mine between 280-290hp because of this. See https://www.miataturbo.net/suspensio...es-dust-75506/ for a discussion on gearboxes and high-powered MX5s

Last edited by Lokiel; 11-25-2013 at 08:32 PM. Reason: Added PS
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Old 11-25-2013, 08:24 PM   #3
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Get whatever forged h beams are the cheapest they are all pretty much the same.


Edit:

Here you go: http://www.ebay.com/itm/161143394160
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Old 11-25-2013, 11:04 PM   #4
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Quote:
Originally Posted by Lokiel View Post
After doing some research for my engine build, I settled on K1 rods because they are among the lightest of the Tier-2 brands, and

"K1 has also called upon the experts at ARP fasteners to design special K1 proprietary rod bolts with asymmetrical threads to equally load each thread when under pressure. "
(see 89-05 Mazda Miata Connecting Rods: JSC Speed)

Most engine builders here in Australia recommend Carillo rods since they know that they'll never fail in an MX5 since they're rated at >1000hp but all the brands you listed (K1, Manley, Eagle) can handle 600hp which is double what a high-hp MX5 can deliver anyway so the risk is negligible and they're half the price.

PS: You indicated you want about 350-400hp. Are you aware that you'll run into gearbox issues at these levels? The MSM 6-speed tends to crap out above 300hp and the 6-speeds are the toughest factory gearboxes. I intend to limit mine between 280-290hp because of this. See https://www.miataturbo.net/suspensio...es-dust-75506/ for a discussion on gearboxes and high-powered MX5s
i was liking the K1 pretty much, not much seems to be using them tho...


For the tranny, i'm aware, i already got my second 6 speed in stock(msm).
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Old 11-25-2013, 11:24 PM   #5
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Is there any reason why you're not building a VVT head?
Also any cheapest rods will do. Save your pennies and buy a twin disk clutch instead.

I personally regret not balancing my engine. It runs perfectly well but sounds like a tractor and is quite rough.... and now its toooo lateeee
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Old 11-26-2013, 12:03 AM   #6
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Quote:
Originally Posted by Lokiel View Post
PS: You indicated you want about 350-400hp. Are you aware that you'll run into gearbox issues at these levels? The MSM 6-speed tends to crap out above 300hp and the 6-speeds are the toughest factory gearboxes. I intend to limit mine between 280-290hp because of this. See https://www.miataturbo.net/suspensio...es-dust-75506/ for a discussion on gearboxes and high-powered MX5s
Its not power that breaks transmission, its torque. You can crack 400hp (dynojet) on even a 5 speed if you keep the torque to 250ftlbs (I think thats 400000 kg/NM*sqrt(Pi) in Australian torque units) and just rev the car out.
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Old 11-26-2013, 01:16 AM   #7
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Quote:
Originally Posted by paNX2K&SE-R View Post
Get whatever forged h beams are the cheapest they are all pretty much the same.


Edit:

Here you go: For Mazda Miata MX5 323 GTX Ford Escort Connecting Rods Rod Conrods Arp Bolts | eBay
I bought these last night, he shipped them out this morning. I made an offer of 199 plus 16 shipping, he countered and we ended up on 209+16 shipping.
MAZDA1 6L 1 8L B6 BP NB ZM H Beam Rod 5 230" 4pcs A Set w Arp 3 8" Bolts | eBay
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Old 11-26-2013, 06:03 AM   #8
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Quote:
Originally Posted by soviet View Post
Is there any reason why you're not building a VVT head?
Also any cheapest rods will do. Save your pennies and buy a twin disk clutch instead.

I personally regret not balancing my engine. It runs perfectly well but sounds like a tractor and is quite rough.... and now its toooo lateeee
This.

Unless you plan on going well above 500hp, and or tracking it. I've noticed a lot of people having great success with cheap rods.
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Old 11-26-2013, 03:22 PM   #9
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I went with Manley too. Why, Trackspeed, 949, and other hardcore racers use them, period....
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Old 11-26-2013, 07:10 PM   #10
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... and they sound "Manly"!
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Old 11-26-2013, 07:42 PM   #11
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I like my rods as manly as possible.
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Old 11-26-2013, 09:09 PM   #12
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Quote:
Originally Posted by soviet View Post
Is there any reason why you're not building a VVT head?
Also any cheapest rods will do. Save your pennies and buy a twin disk clutch instead.

I personally regret not balancing my engine. It runs perfectly well but sounds like a tractor and is quite rough.... and now its toooo lateeee
Why no vvt? because i got a bp4w in stock.

Quote:
Originally Posted by Erat View Post
This.

Unless you plan on going well above 500hp, and or tracking it. I've noticed a lot of people having great success with cheap rods.
My head is having a problem with cheap interns... Not that i don't believe you guys, i just CAN'T build an engine, knowing i got cheap ebay interns.

Quote:
Originally Posted by Lokiel View Post
... and they sound "Manly"!
i lol'ed!
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Old 11-26-2013, 11:33 PM   #13
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Quote:
Originally Posted by sr20det_28 View Post
My head is having a problem with cheap interns... Not that i don't believe you guys, i just CAN'T build an engine, knowing i got cheap ebay interns.
I built my motor with USED internals and a JUNKYARD head I pulled myself at a pick and pull.
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Old 11-27-2013, 06:08 AM   #14
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Originally Posted by sr20det_28 View Post
My head is having a problem with cheap interns... Not that i don't believe you guys, i just CAN'T build an engine, knowing i got cheap ebay interns.
I never said anything about using ebay parts in your head.

You should read around this forum more, even build threads. People have bad luck with ebay head parts. But good luck with the "ebay" rods.

Like i said, people, including myself use scat rods and they work fine.

It's your money. Do what you want with it.
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Old 11-27-2013, 09:25 AM   #15
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Quote:
Originally Posted by soviet View Post
I built my motor with USED internals and a JUNKYARD head I pulled myself at a pick and pull.
i did'nt it could'nt be done! but for a 100$ishhh difference between ebay and Manley, the choice seems kind of easy, no? Don't forget i live in canada, so shipping and taxes don't make that ebay rod so tasty.

Quote:
Originally Posted by Erat View Post
I never said anything about using ebay parts in your head.

You should read around this forum more, even build threads. People have bad luck with ebay head parts. But good luck with the "ebay" rods.

Like i said, people, including myself use scat rods and they work fine.

It's your money. Do what you want with it.
Sorry, i was talking bottom end My bad!

What do you guys think of this kit?
Wiseco Forged Pistons Manley H Beam Rods Mazda Miata BP 323 1 8L 8 5 1 84mm | eBay
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Old 11-29-2013, 12:28 AM   #16
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Why don t you try supertech route? Pretty happy with mines.
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