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I had a chance to compare some miata engine components last night; a set each of carrillo h-beams and manley h-beams. Laying them side by side, there is quite a difference. The manley's have quite a bit beefier big end, probably needed to house the 3/8" bolt; (the corrillo's have 5/16"). Both sets were closely weight matched on the big end. The total weight had a spread of of+/- 0.4 g (carrillo) and +/- 0.7 g (manley); which is good as I don't think that you want to grind into their shot peened surface to balance if you don't have to. The biggest difference was the weight. The manley's were 20% heavier than the carrillo's; most all of this was at the big end.
OEM a-beam rod: total 551.9g
Manley h-beam rod: big end 382.9g; total 538.3g
Carrillo h-beam rod: big end 317g; total 455.1g
The JE piston set, while similar in weight to OEM, appeared to have a more robust crown. They also appeared to have moved the ring package down sightly (approx .020) from the crown.
OEM piston: 294.5g; pin 80g
JE piston: 295.2g; pin 89g
I had questions about which ones to buy, but couldn't find a comparison online... only manufacturer marketing descriptions. After looking at these side by side, it looks like the carrillo was able to save weight by using a smaller bolt and smaller big end boss while using better materials. That being said, the 100g of rot/recipricating weight probably only benefits those spinning the motor at high rpm. Both can easliy handle the power loads. I think that the china rods are a clear winner here... a better match for most of our miata motors spinning 7k... and at 1/3 the cost!
I had questions about which ones to buy, but couldn't find a comparison online... only manufacturer marketing descriptions. After looking at these side by side, it looks like the carrillo was able to save weight by using a smaller bolt and smaller big end boss while using better materials. That being said, the 100g of rot/recipricating weight probably only benefits those spinning the motor at high rpm. Both can easliy handle the power loads. I think that the china rods are a clear winner here... a better match for most of our miata motors spinning 7k... and at 1/3 the cost!
Thanks for the comparison and info! That's pretty cool to see. I have used both of these rods, I now run the carrillo's. I didn't know they were lighter. I thought the bolts looked smaller, cool to now know that was actually the case. I bet the carrillo bolt is stronger, supposedly they are rated at something like 300ksi ultimate strength or something absolutely absurd like that.
Codrus, any idea where you saw the 600hp rating on the carrillo? I just assumed they could handle 800-1000. Asking for a friend.
Codrus, any idea where you saw the 600hp rating on the carrillo? I just assumed they could handle 800-1000. Asking for a friend.
A "friend", heh
600hp is just my vague recollection of what Jeremy said when I called up FM to buy motor parts for my first build about 8 years ago. Something like "if you want to make 400 hp buy the A beams, if you want to make 600 hp buy the H beams". So don't take it as a hard limit, I've never heard of anyone breaking one.
(I bought the A beams because they're less expensive and even lighter than the H beams. 432g for A-beam, 447g for H-beam, and something like 540g for stock)
I did some searching, and the rods I have, but with the 3/8 CARR bolts, are rated for 1,000 HP. So I will assume the ones I have are not as strong with the 5/16 bolts. Still I doubt I'll ever break one.
One can order Carrillo H's with 3/8 CARR bolts. We have put a few engines together with them. The billet crank 1.9L with TSE 6758 dyno we posted a while back had them for example. Not a website option. Stoopid expensive but a good idea for big boost and lotsa 8k+ time.
We broke a Carrillo A beam with 5/16" bolts but it wasn't the rods fault. 9000rpm on a mostly stock crank at 180whp did it in. Mains and rod journals looked like poo.
When I built my engine I did plenty of research and basically found the Carrillo rods were rated at 1,000hp and Eagle/Manley/K1 rods were rated at 600hp,
Given that the Carrillo rods were at least twice the price of the China rods and that I planned to run under 300rwhp, I bought the K1 rods AND CP pistons with top coating for the price of the Carrillo rods alone - and I'm still massively overbuilt.
In Australia, Carrillo rods are worth ~A$1,000 and most engine builders prefer to use Carrillo rods because they're light, already balanced, strong and quality is second to none - there's no additional work needed and almost no chance of defects which is good for them.
One can order Carrillo H's with 3/8 CARR bolts. We have put a few engines together with them. The billet crank 1.9L with TSE 6758 dyno we posted a while back had them for example. Not a website option. Stoopid expensive but a good idea for big boost and lotsa 8k+ time.
We broke a Carrillo A beam with 5/16" bolts but it wasn't the rods fault. 9000rpm on a mostly stock crank at 180whp did it in. Mains and rod journals looked like poo.
I've spun a stock crank to 9K with my carrillo H-beams with the 5/16 bolts, and the H's are heavier... That's scary. Why do you think the rod bolt failed? RPM, or loading/balancing issue?
Also, what is stupid expensive? My H-beams were 1200.
EDIT: After rereading your post, why did the bearings look like poo? I'm assuming you're saying the rod failed because of a bearing failure first?
Bit off topic but has anyone tried the $700 billet aluminum rods. They are fairly cost effective and can be built for either high HP or high revs. The local wrx guys have been running them for years and some have done over 100k kms on the street and hard track work with them. This is in 500whp plus cars.
Emilio, I'm planning on upping my rev limiter from 8500 to 9000 as thats where my power curve is. I run Crower A beam rods with 5/16 ARP 2000 bolts. I don't have any experience past 8500 as previously I was held back by my valve train so I don't know the risk of failure. Are 5/16 bolts enough for 9000 or are they too risky? If its the bearings then thats fine as I can woek to a replacement schedule but if its outright failure thats not so great.
I thought aluminum rods were for occasional use drag cars, not extended road course? Due to the fatigue issue?
--Ian
This is my understanding. Aluminum rods would break from fatigue in a stock motor if driven enough. How many miles? Depends. In drag racing if you drive your car on the street at all, you usually don't run aluminum rods. If you only race it's fine since you'll rebuild and throw them away before they fail from fatigue. I have heard of folks putting 20K miles on aluminum rod motors but that's not common.
I thought aluminum rods were for occasional use drag cars, not extended road course? Due to the fatigue issue?
--Ian
I asked this of the WRX builder and he pointed out the rods they are using are rated for over 1400 hp. They are only using them at 30-40% load so they don't even get close to stressed. Most of the local high performance WRXs are now built with them even if just run as a street car and all the ally rod motors he has done havn't had a single failure. He had more failures with the non aluminium rods.
Most rods fail due to bearing failure more so than HP and since the ally rods are lighter and softer there is far less load on the bearing.
I might try them next build... but then I'm not doing kms on the street.
05-01-2017, 12:54 PM
carrillo vs. china rods
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