Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Engine Performance (https://www.miataturbo.net/engine-performance-56/)
-   -   carrillo vs. china rods (https://www.miataturbo.net/engine-performance-56/carrillo-vs-china-rods-93041/)

gtred 05-01-2017 12:54 PM

carrillo vs. china rods
 
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
https://cimg9.ibsrv.net/gimg/www.mia...92c3c0c5c9.jpg


https://cimg7.ibsrv.net/gimg/www.mia...440dd5e01a.jpg
https://cimg3.ibsrv.net/gimg/www.mia...7a6490c698.jpg

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 89ghttps://cimg9.ibsrv.net/gimg/www.mia...0487d1cbcf.jpg

ryansmoneypit 05-01-2017 01:45 PM

did I miss the China anything?

concealer404 05-01-2017 01:47 PM


Originally Posted by ryansmoneypit (Post 1410304)
did I miss the China anything?

The Manleys.

Art 05-03-2017 06:46 PM

.

Monk 05-03-2017 07:23 PM

I think the 3/8" bolt already makes the Manley more appealing to me.

codrus 05-03-2017 07:43 PM

IIRC the Carrillo H-beam is rated to 600 hp, even with the 5/16" bolt. Maybe Pat needs something bigger, but I'm not sure anyone else here does. :)

Carrillo much lighter, but much more expensive.

--Ian

bahurd 05-03-2017 08:12 PM

Feelin Manley... :rofl:

gtred 05-03-2017 09:41 PM

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!

Art 05-03-2017 09:48 PM

.

aidandj 05-03-2017 10:05 PM

There are some China rods out there with 5/16 bolts. So careful when you order.

patsmx5 05-04-2017 12:21 AM


Originally Posted by gtred (Post 1411037)
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 05-04-2017 02:56 AM


Originally Posted by patsmx5 (Post 1411087)
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)

--Ian

patsmx5 05-04-2017 10:08 PM

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.

emilio700 05-05-2017 09:30 PM

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.

Lokiel 05-05-2017 09:46 PM

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.

patsmx5 05-05-2017 09:47 PM


Originally Posted by emilio700 (Post 1411662)
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?

Madjak 05-06-2017 12:43 AM

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.

codrus 05-06-2017 12:54 AM

I thought aluminum rods were for occasional use drag cars, not extended road course? Due to the fatigue issue?

--Ian

patsmx5 05-06-2017 12:59 AM


Originally Posted by codrus (Post 1411685)
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.

Madjak 05-06-2017 01:11 AM


Originally Posted by codrus (Post 1411685)
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.

patsmx5 05-06-2017 01:34 AM

Temp vs yield strength for some aluminum alloys.
https://cimg6.ibsrv.net/gimg/www.mia...2f9de17d54.jpg

I wonder how much hotter the big and small end of a connecting rod can get above oil temps?

My thought is in a drag motor, no problem. A street car that sees high oil temps could fail very quickly.

Madjak 05-06-2017 02:20 AM

We should really move this to its own thread.

If aluminium rods fail from heat then why are we using forged aluminium pistons? We don't question them and they see bigger heat loads and just as large forces. I know from the local WRC racers that they aren't seeing any problems with ally rods and some are pushing big big power with heat issues. From that info I'm willing to try them next build.

codrus 05-06-2017 04:11 AM

AIUI (I'm a software guy, not a mechanical engineer or a metallurgist), steel has a "fatigue limit", and loads below this limit will add zero fatigue to the piece. Aluminum, OTOH, has no such limit, and thus any load placed on an aluminum part will add a measurable amount of fatigue. (https://en.wikipedia.org/wiki/Fatigue_limit) What this means is that if a steel part is operated below that limit, it can be run through an infinite number of cycles without failing due to metal fatigue. Aluminum cannot, it will always have a maximum number of cycles. You can make that maximum number larger by decreasing the load or increasing the size of the part, but you can't remove the limit.

Googling for random articles on this, I found this one: Debunking Aluminum Rod Myths With GRP - Dragzine

They say in there that nitro cars might get 25 passes out of a set of aluminum rods, but mild bracket racing cars can get "hundreds and hundreds" of passes. They add that the manufacturers do not recommend aluminum rods for street cars with expected lifetimes of 100K miles. Given that your average road course car is going to do the equivalent of 4 or 5 drag strip passes worth of acceleration every lap, and your average track day is going to involve 40-50 laps, "hundreds and hundreds" doesn't sound like very long to me.

As for aluminum pistons, they see a much lower tensile load than a rod does (because they aren't pulling another piston), and they also have a much larger cross-sectional area in the direction of that load.

--Ian

patsmx5 05-06-2017 12:30 PM


Originally Posted by Madjak (Post 1411696)
We should really move this to its own thread.

If aluminium rods fail from heat then why are we using forged aluminium pistons? We don't question them and they see bigger heat loads and just as large forces. I know from the local WRC racers that they aren't seeing any problems with ally rods and some are pushing big big power with heat issues. From that info I'm willing to try them next build.

Rods see higher loading than pistons, and the stress (force/area) is way way wayyyyy higher on a rod than a piston. Also as mentioned already fatigue failure is the concern, and to "improve" the fatigue life of an aluminum part you need to make it big and spread out the load as to reduce the stress. To make an aluminum rod big enough to last as long as a steel rod, it would be heavier than a steel rod. I'm sure you can run them in a racecar only, folks do that with success. I don't think any OEM with a 100k+ mile engine life runs them for reliability sake. For a racecar you can trade endurance for weight savings, and the weight savings buy you RPM and power handling improvements beyond a steel rod for the life of the part. That's why very high HP motors run them.

bonez8 05-08-2017 01:45 AM


Originally Posted by codrus (Post 1411711)

Googling for random articles on this, I found this one: Debunking Aluminum Rod Myths With GRP - Dragzine



--Ian

That's the same arrival that I've read lots of times. I'd like to try it on a spare motor for a light revy motor. But mine will be purely agreed so I won't be as hard on it and a lot of folks on here.
every time I research it there is very little I'll put there for street or road coarse cares just pure drag cars.
It's a long way out before I'll give it a go though.

Bone

Art 05-08-2017 03:02 AM

.

afm 05-08-2017 03:17 AM


Originally Posted by Art (Post 1412113)
My very vague memory is that aluminum can be made lighter per strength than steel, or stronger per weight, but it's not by a lot. For a race car however a little bit can be enough to matter.

Not at >250 degrees Fahrenheit.

Art 05-08-2017 03:22 AM

.


All times are GMT -4. The time now is 08:30 PM.


© 2024 MH Sub I, LLC dba Internet Brands