[Aaron Quinton]

Thank you for sharing.

Originally Posted by mgarblik

Better pics of Eagle stuff.

[Aaron Quinton]

I don't think BES owns the approach but I appreciate your candor.

Originally Posted by Jeff Kinsler

Yea I will not post it for the reason above but anyone can send their stuff there to get it machined. I think it actually was talked about on py somewhere and people were saying that's not a good way to do it.

[v869tr6]

Have been running my 4.5" stroke Scat crank for 12 years. Has seen I would guess at least 25,000 street miles and I get out to the strip a few times a year. Two different times I melted pistons back in 2006 and 2007. Been running at least a few 8 second passes each year since 2008. Short block has been together for the last 9 years, and it's a 1970 factory block, Eagle rods and Ross pistons. This is with a turbo.

[Hooter]

Originally Posted by v869tr6

Have been running my 4.5" stroke Scat crank for 12 years. Has seen I would guess at least 25,000 street miles and I get out to the strip a few times a year. Two different times I melted pistons back in 2006 and 2007. Been running at least a few 8 second passes each year since 2008. Short block has been together for the last 9 years, and it's a 1970 factory block, Eagle rods and Ross pistons. This is with a turbo.

How have your piston skirts looked and what length rod are you running? I had less than favorable results with a 4.75 crank and 6.7 rods in a street application with several thousand street miles.

[v869tr6]

Originally Posted by Hooter

How have your piston skirts looked and what length rod are you running? I had less than favorable results with a 4.75 crank and 6.7 rods in a street application with several thousand street miles.

6.7" rods, short block hasn't been apart in 9 years.

[GTO JONES]

How many are running a 4.75 crank?

[Douglas Willinger]

Anyone have any information on experience with the MOLNAR 4.375" and or 4.65" stroke 3" main journal crankshafts? For instance the cylinder wall wear?

[PAUL K]

Originally Posted by Douglas Willinger

Anyone have any information on experience with the MOLNAR 4.375" and or 4.65" stroke 3" main journal crankshafts? For instance the cylinder wall wear?

We've been building 4.375 stroke Pontiac engines for decades (not with Molnar crankshaft) and it makes great combination . No issues whatsoever. Not much experience with the 4.65 stroke.

[Hooter]

I destroked my motor from a 4.75 Ohio to a Molnar 4.375. Both used same 6.7 rod. Less side loading on the pistons and able to get the pin out of the ring land(no ring supports). Crank was spot on. Only about 2,000 street miles and 10 passes, but so far so good.

[lust4speed]

Originally Posted by Jack Ferris

Great information Jeff.
I have a new SG 4.500 crank that came from AP but I’ve not heard a lot of feedback on them so I’m hesitant to use it. I do have a 4.250 SCAT crank so your post has been a plus.

My SG 4.500 crank is going on 3 years of racing with no problems. Mild 700 HP build shifting at 6,800 RPM. Had it checked and mag'd by the machine shop when first purchased and it was good to go.

[Jack Ferris]

Originally Posted by lust4speed

My SG 4.500 crank is going on 3 years of racing with no problems. Mild 700 HP build shifting at 6,800 RPM. Had it checked and mag'd by the machine shop when first purchased and it was good to go.

Thank you. My goal for this build is 860-880 HP. There are many opposing views on this particular brand of crankshaft, even on the "other brand" sites but most, if not all speak of the final machining process being the deal breaker and speak little about strength. I have to assume that no matter which company finishes them if they are overseas forgings they are very similar in overall strength. I'm sure some have been broken and I have spoken to a few in the bowtie camp that have broken an overseas forging, but that's where the story ends. No hows or why they failed. Mr. Kinsler's information is priceless as we all know the level of power he makes.

[Douglas Willinger]

Originally Posted by PAUL K

We've been building 4.375 stroke Pontiac engines for decades (not with Molnar crankshaft) and it makes great combination . No issues whatsoever. Not much experience with the 4.65 stroke.

Is that with or without any amount of filling in any of the water jacket area?

I read somewhere that such was required with the 4.5" stroke to avoid cylinder wall scuffing.

Would very much like to see some stories of the 4.375" builds.

[PAUL K]

Originally Posted by Douglas Willinger

Is that with or without any amount of filling in any of the water jacket area?

I read somewhere that such was required with the 4.5" stroke to avoid cylinder wall scuffing.

Would very much like to see some stories of the 4.375" builds.

All the builds were performance deals so the the blocks were filled atleast to the water pump holes.

[PAUL K]

Originally Posted by Jack Ferris

Thank you. My goal for this build is 860-880 HP. There are many opposing views on this particular brand of crankshaft, even on the "other brand" sites but most, if not all speak of the final machining process being the deal breaker and speak little about strength. I have to assume that no matter which company finishes them if they are overseas forgings they are very similar in overall strength. I'm sure some have been broken and I have spoken to a few in the bowtie camp that have broken an overseas forging, but that's where the story ends. No hows or why they failed. Mr. Kinsler's information is priceless as we all know the level of power he makes.

I agree with all the above. Sometime research the 500557 block lol. We've used a handful of SGI cranks and never had issues with there cranks. A couple had oversized main journals but we skimmed them down to STD spec. For a while they were the only option for the 3.25 main 4.5 stroke crank.... they might still be??

[Douglas Willinger]

Originally Posted by PAUL K

All the builds were performance deals so the the blocks were filled atleast to the water pump holes.

So as to avoid the cylinder wall scuffing, is such a partial water jacket filling required for a 4.375" stroke. Or for a 4.25" or even 4.0"?

[ponjohn]

Originally Posted by PAUL K

We've been building 4.375 stroke Pontiac engines for decades (not with Molnar crankshaft) and it makes great combination . No issues whatsoever. Not much experience with the 4.65 stroke.

Stock block?

[PAUL K]

Originally Posted by Douglas Willinger

So as to avoid the cylinder wall scuffing, is such a partial water jacket filling required for a 4.375" stroke. Or for a 4.25" or even 4.0"?

Filling the block seems to help everything, from what we've seen in our experience. However the Boss Bird guys have had success without ever using block fill. I can't say it's a necessity but almost every serious effort stock block build we've done has been filled.

[PAUL K]

Originally Posted by ponjohn

Stock block?

Both but more stock block builds than aftermarket.

[krisr]

Originally Posted by PAUL K

Filling the block seems to help everything, from what we've seen in our experience. However the Boss Bird guys have had success without ever using block fill. I can't say it's a necessity but almost every serious effort stock block build we've done has been filled.

Half fill? Just to help keep the mains a bit more rigid or are you talking more full fill and run alky?

[hojs69]

GTO JONES's
Senior Member

How many are running a 4.75 crank?



GTO Jones.......You are one of the few it appears.