Turbo'd con-rod preferences?

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gagembassett

gagembassett

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So recently bought a rotating assembly from a fellow FABO member. Fully balanced stock 3.58 stroke 360 assembly with Ross pistons, eagle cast steel crank and SIR rods. The plan is for a Turbo 360 build using this assembly however I would like to see opinions on if those rods will hold up. I'd say somewhere in the 650 HP range on 8 psi of boost from an On 3 Racing 88mm single turbo. I trust the pistons and crank will be okay the only thing I have an "iffy" feeling about are the SIR rods. I have talked to several people running stock rods on 20+ lbs of boost and several around 550ish HP range. I know boosted HP is a different animal than N/A HP so just curious if people think the SIR rods will be okay?
 
Sorry but honest opinion here, I’d trust the SIR rods LONG before I’d trust an eagle cast crank.
 
TT5.9mag said:
Sorry but honest opinion here, I’d trust the SIR rods LONG before I’d trust an eagle cast crank.
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I can understand that, I think most of it comes from the 4 inch stroker cranks breaking. Haven't heard much about the stock stroke cranks however whether good or bad
 
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The last sentence of the paragraph above pretty much sums it up for me.
Summit lists 500hp as the limit of those rods. Now all that being said, I’ve made more hp than that on stock cast crank 360s with stock rods so yrmv
 
gagembassett said:
It does say that in the description but I would've assumed with the low psi it would be okay, I'll call them
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Yeah, I’m curious as to why Ross states not recommended for Turbo Applications but can be used with Nitrous upto a 250 shot….
2618 is great for a boosted application. It seems the top ring is far enough away from the piston crown too.
Keep us posted.
 
Just called Ross' number and talked with a tech member. After mentioning that it says 250 shot of nitrous and wondering why/if boost couldn't be used instead they did get back to me saying that 10 psi or less is okay and will work. Although I won't be going higher than that I'd think it could be pushed a little more than that as parts seem to usually be rated low
 
**My mistake, it is a Scat cast steel crank**
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Called Eagle as well and talked about it. He said they are not intended for that but also to not take HP ratings literally mentioning "an improperly tuned 250 HP engine can blow and a properly tuned 650 HP can live"
 
gagembassett said:
Just called Ross' number and talked with a tech member. After mentioning that it says 250 shot of nitrous and wondering why/if boost couldn't be used instead they did get back to me saying that 10 psi or less is okay and will work. Although I won't be going higher than that I'd think it could be pushed a little more than that as parts seem to usually be rated low
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Yeah. I'm sure he really went to the drawing board to come up with that figure.
 
88mm is a lot of compressor for only a 650hp goal. A 78/75 would get there with way easier packaging and spool time. An s475 would be a smaller package as well and still have a large enough backside to make power up top. A stock stroke 360 will feel lazy on the street with a 88 in my opinion.
 
I would trust a reworked factory Chrysler rod with good rod bolts before anything from China. I have never seen a broken factory rod just break right by itself. There was always another factor involved.
 
MiradaMegaCab said:
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Yeah, I’m curious as to why Ross states not recommended for Turbo Applications but can be used with Nitrous upto a 250 shot….
2618 is great for a boosted application. It seems the top ring is far enough away from the piston crown too.
Keep us posted.
Click to expand...
Probably cause a turbo application could ad a LOT more boost, cylinder pressure, and hp, than a 250 shot.
As stated above, I would build those components as an n/a motor, and add a small nitrous shot..... and start over for a turbo, with a forged 4340 crank, h-beam rods, and some 8.5-9 to 1 blower pistons..... and run 12 lbs of boost.
 
I would throw those SIR rods right in the frickin garbage. I did a few dirt 360's for a local kid. First one was a 9 to 1 B mod engine. Used those rods to keep the Bob weight down. He broke a rod in that one. No valvetrain issues, definitely no oiling issues. It just flippin broke. He only turned the thing 6500.
 
I ran Eagle SIR rods in my n/a 340 with no issues but wouldn't consider them for a boosted application, decent rods aren't that expensive.
 
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