Any blown 5.7's on here?

[2010 Infantry Vet]

Just trying to see if anyone has had major problems at 6psi. Our motors have 10.5 compression, which is not ideal to being blown at 8.5-9 compression. When my motor gets tired, I'll probably stroke it to 392 with forged internals. Then add the whipple.

 

[chrisp2493]

I’m not boosted, but just throwing this out there. The guy that does my tuning has a 10.5 compression motor and is running ~15lbs of boost haha. The problem with the stock Hemi internals in the top ring land on the piston, it’s pretty small. And the ring gaps from the factory are too small for big boost. Here’s a factory piston next to the upgraded forged Manley piston that’s in my truck now.

 

[2010 Infantry Vet]

I’m not boosted, but just throwing this out there. The guy that does my tuning has a 10.5 compression motor and is running ~15lbs of boost haha. The problem with the stock Hemi internals in the top ring land on the piston, it’s pretty small. And the ring gaps from the factory are too small for big boost. Here’s a factory piston next to the upgraded forged Manley piston that’s in my truck now.

15# on stock motor
How many miles has he been running it??? Guy that built my motor in my mustang ran 15 pounds on a 2valve 4.6 with cams and make 600RWHP but it blew after 2 weeks. And stock 2 valve has 9:1 compression!

 

[chrisp2493]

15# on stock motor
How many miles has he been running it??? Guy that built my motor in my mustang ran 15 pounds on a 2valve 4.6 with cams and make 600RWHP but it blew after 2 weeks. And stock 2 valve has 9:1 compression!

No no not stock motor, it’s a forged stroker. I’m just saying he’s running a high compression boosted Hemi. It’s not the compression *as much* as it’s the ring lands that’s the problem with the stock motors

 

[charonblk07]

The stock pistons will handle 8-9psi with decent tuning. I’ve known guys who have pushed that to 11psi with dedicated water/**** injection knowing full well that if it fails or runs dry they’re buying a new engine. The limiting factor when it comes to the CR is the fuel you can use. At 8 psi you’re at the limit of what 93 e10 pump gas can handle for knock resistance. You can run higher boost or CR if you want to run dedicated to e85 or race fuel but that’s a dedicated swap.


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[2010 Infantry Vet]

The stock pistons will handle 8-9psi with decent tuning. I’ve known guys who have pushed that to 11psi with dedicated water/**** injection knowing full well that if it fails or runs dry they’re buying a new engine. The limiting factor when it comes to the CR is the fuel you can use. At 8 psi you’re at the limit of what 93 e10 pump gas can handle for knock resistance. You can run higher boost or CR if you want to run dedicated to e85 or race fuel but that’s a dedicated swap.


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Thanks I didnt know this. Guy that built my 5.0 stroker for my mustang said dont go any higher than 9:1
I was running 20# on 93 octane. Thing was insane.
I have heard a lot of bad things about the ring lands on the 5.7 hemi.

 

[2010 Infantry Vet]

No no not stock motor, it’s a forged stroker. I’m just saying he’s running a high compression boosted Hemi. It’s not the compression *as much* as it’s the ring lands that’s the problem with the stock motors

Oh ok. Does he have the 392? I have been looking at that stroker kit.

 

[chrisp2493]

Oh ok. Does he have the 392? I have been looking at that steoker kit.

Yep he does. I suggest checking out Hemi Truck Club for some great info on stroker builds. About all the guys on there (including myself) have strokers, and most of them are boosted to come level. Lots of very knowledgeable engine builders there

 

[charonblk07]

Thanks I didnt know this. Guy that built my 5.0 stroker for my mustang said dont go any higher than 9:1
I was running 20# on 93 octane. Thing was insane.
I have heard a lot of bad things about the ring lands on the 5.7 hemi.

It all depends on how you setup the engine and the engine design. The dual spark plug setup in the hemi does allow the ignition event to occur later in the compression cycle because the flame propagation and combustion event are a lot shorter compared to other engine designs; this can allow a lower octane fuel to be used compared to a different engine design with a similar CR. I’m running 17-18psi with my 9.6CR on 94 e10 in my truck; I’d be running e85 if it was available in Canada.


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[Tach_tech]

Mine put a rod through the block at 7psi. Has forged rods and pistons now, CR down to around 9.7 now.

 

[Pull Ya]

^^^^ Did that happen recently?
Jay

 

[2010 Infantry Vet]

Mine put a rod through the block at 7psi. Has forged rods and pistons now, CR down to around 9.7 now.

When i build mine, i dont think I will be going over 9:1

 

[Tach_tech]

^^^^ Did that happen recently?
Jay

Happened early December.

 

[Tach_tech]

When i build mine, i dont think I will be going over 9:1

At less then 10 psi even 10:1 is fine. There’s lots of 5.7 trucks running 10psi with no issues. The CR isn’t the issue with boost for the hemi, it’s the thin top ring land and hyperutectic pistons. Even with those issues it can still be done reliably and safely. Ya mine blew but buddy of mine has the exact same set up and rides his harder and has had no issues. It’s all about the tune and not being stupid with it. Either that or doing preventive measures such as forged rods and pistons.

I went with a thicker head gasket and the MMX rod and piston package. Between the two it lowers it to around 9.7. I could run a fair bit more boost now if I wanted to but I’ll probably still keep it to a max of 10psi.

 

[dmillar74]

At work, we had a 2007 5.7 Hemi failure at around 165,000 miles. Not sure why.


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[2010 Infantry Vet]

At less then 10 psi even 10:1 is fine. There’s lots of 5.7 trucks running 10psi with no issues. The CR isn’t the issue with boost for the hemi, it’s the thin top ring land and hyperutectic pistons. Even with those issues it can still be done reliably and safely. Ya mine blew but buddy of mine has the exact same set up and rides his harder and has had no issues. It’s all about the tune and not being stupid with it. Either that or doing preventive measures such as forged rods and pistons.

I went with a thicker head gasket and the MMX rod and piston package. Between the two it lowers it to around 9.7. I could run a fair bit more boost now if I wanted to but I’ll probably still keep it to a max of 10psi.

Do they offer the forged stroker kit in 9:1 compression?

 

[Tach_tech]

Do they offer the forged stroker kit in 9:1 compression?

Honestly I’m not sure, someone might but unless you’re planning on running pretty high boost you don’t need to go that low.

 

[charonblk07]

Mine put a rod through the block at 7psi. Has forged rods and pistons now, CR down to around 9.7 now.

You should know the rules by now ... pics or it didn't happen.

 

[Wild one]

Honestly I’m not sure, someone might but unless you’re planning on running pretty high boost you don’t need to go that low.

Now that it's bulletproof are we gonna see your truck at either the Hat or Castrol this year Dan,lots of guys are interested,lol
Rick

 

[charonblk07]

Do they offer the forged stroker kit in 9:1 compression?

The lowest I've seen is 9.6CR which is plenty low enough for the hemi on 94 e10 pump gas; I dropped mine a bit more by running a double thick Cometic MLS head gasket.