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Hello,
I am new to this group. I am building a 455-488 Stroker. Purchased a eagle kit , forged rods 7,1 forged Mahle pistons. Had this crank balanced .External balance. Some weight was taken out of the crank. How ever the kit has a Eagle Cast steel Crank. I assume because. This motor is going in a street car, weekend , summer driver, track twice a year. will melt tires as often as possible 5500 rpm. projected HP 500-550 Torque over 600. Roller cam, 538 intake and exhaust .236 @ 50 Intake, 244 @ 50 exhaust ,110 Lobe separation. 1.7 Rockers.
Question I have. does anyone have experience with these eagle cast cranks? I just seen a post on facebook, a guy broke a crank at 500 miles on fresh motor. I know this opens up a lot of questions , assembly, balance, machining, how do we know the crank broke first and not block cracking. But, does any here have first hand experience with this stroker kit or similar, 496 is the same crank. Did it last?
My only "first hand experience" you requested is this: in 2015, when I first set out to have a serious Olds BB built (because I suck), I was going to go 496. I had already purchased an ATI balancer for an internal balance. The Eagle crank needed an exorbitant amount of Mallory metal to get into spec. At that point, I aborted the 496 in favor of a 468 via a forged steel 425 crank that was offset ground to Chevy rod journals at 4.24" stroke. I still used the 7.1 rods and CP pistons that a 496 would require.
From what I understand, the nodular iron/"cast steel" cranks still have a bunch of flex. The only real way to reduce it is a well designed full girdle that ties the main caps to the pan rails. Large-ish oil clearances help, but aren't the absolute cure.
Second hand experience is from a bracket racer in Jersey. He broke several Eagle cranks, and I think he may have just gone back to traditional N cranks- not sure.
Another big problem is rod and piston weight. A long time gearhead coworker once told me: "The problem with Oldsmobiles is that they have big, heavy rods and big, heavy pistons." He's not wrong.
From what I understand, the nodular iron/"cast steel" cranks still have a bunch of flex.
There is truth to this. The material property that governs inherent stiffness is called the Modulus of Elasticity (also known as Young's Modulus). Most steels (cast, forged, billet - all pretty much the same) have a modulus around 29 x 10^6 PSI. Grey iron has a modulus anywhere from 10 x 10^6 to 23 x 10^6, depending on the specific composition. Ductile iron runs about 24 x 10^6. By comparison, aluminum runs about 10 x 10^6 PSI, so aluminum girdles and main caps are really worthless unless they are so massive that the section properties overcome the lower stiffness.
Hello,
I am new to this group. I am building a 455-488 Stroker. Purchased a eagle kit , forged rods 7,1 forged Mahle pistons. Had this crank balanced .External balance. Some weight was taken out of the crank. How ever the kit has a Eagle Cast steel Crank. I assume because. This motor is going in a street car, weekend , summer driver, track twice a year. will melt tires as often as possible 5500 rpm. projected HP 500-550 Torque over 600. Roller cam, 538 intake and exhaust .236 @ 50 Intake, 244 @ 50 exhaust ,110 Lobe separation. 1.7 Rockers.
Question I have. does anyone have experience with these eagle cast cranks? I just seen a post on facebook, a guy broke a crank at 500 miles on fresh motor. I know this opens up a lot of questions , assembly, balance, machining, how do we know the crank broke first and not block cracking. But, does any here have first hand experience with this stroker kit or similar, 496 is the same crank. Did it last?
Ive used the eagle 4.5" crank in a couple of 496 builds. one was 14:1 with a big roller cam and steel rods, the other was a 10:1 street engine flat tappet making about what you plan on making. both are still in one piece with lots of runs and street miles on them.
they are not turning a lot of RPM's. maybe 6500 max for the one and under 6k for the street engine. they both have main cap support, thats a must which you need to have if you want it to live.
the eagle cast steel crank has a higher carbon content than iron cranks which is why they can call them steel.... heres the tensile strength of some crank material
cast grey 70,000 to 80,000
cast nodular 95,000
factory forged 10xx series 100,000 to 110,000
cast steel 105,00 to 110,000
5140 forged 115,000
41xx series forged 120,00 to 125,000
4340 series forged 140,000 to 145,000
notice the tensile strength of the factory 10xx forging and the 5140 are very similar to the cast steel...but the forgings are much stronger because they are less brittle and have higher elongation properties
the only thing i found with the eagle cranks i used was their main and rod dimensions were right at the high side. which meant i couldnt get the clearance i wanted using standard bearings. so i had them ground under to my dimensions and used .010' bearings. im not sure if they fixed that but it was a know problem if you wanted more clearance
i know of a few 496's running hard with the factory nodular crank...done right and nitrided, they can work
Last edited by CANADIANOLDS; January 2nd, 2022 at 09:30 AM.
Ive used the eagle 4.5" crank in a couple of 496 builds. one was 14:1 with a big roller cam and steel rods, the other was a 10:1 street engine flat tappet making about what you plan on making. both are still in one piece with lots of runs and street miles on them.
they are not turning a lot of RPM's. maybe 6500 max for the one and under 6k for the street engine. they both have main cap support, thats a must which you need to have if you want it to live.
the eagle cast steel crank has a higher carbon content than iron cranks which is why they can call them steel.... heres the tensile strength of some crank material
cast grey 70,000 to 80,000
cast nodular 95,000
factory forged 10xx series 100,000 to 110,000
cast steel 105,00 to 110,000
5140 forged 115,000
41xx series forged 120,00 to 125,000
4340 series forged 140,000 to 145,000
notice the tensile strength of the factory 10xx forging and the 5140 are very similar to the cast steel...but the forgings are much stronger because they are less brittle and have higher elongation properties
the only thing i found with the eagle cranks i used was their main and rod dimensions were right at the high side. which meant i couldnt get the clearance i wanted using standard bearings. so i had them ground under to my dimensions and used .010' bearings. im not sure if they fixed that but it was a know problem if you wanted more clearance
i know of a few 496's running hard with the factory nodular crank...done right and nitrided, they can work
Forged cranks are more fatigue resistant due to the change in grain structure from forging. Sub zero tempering (cryogenic, freezing) can also improve grain structure. Tuftriding/nitriding adds a hard surface and might contribute to hardness/strength. Camshafts and crankshafts are two items that would benefit from Tuftriding/nitriding in today's world.
Strength is more dependent on the material hardness and alloys. This is why Grade 8 bolts are stronger then Grade 5.
Last edited by OLDSter Ralph; January 2nd, 2022 at 07:24 PM.
My only "first hand experience" you requested is this: in 2015, when I first set out to have a serious Olds BB built (because I suck), I was going to go 496. I had already purchased an ATI balancer for an internal balance. The Eagle crank needed an exorbitant amount of Mallory metal to get into spec. At that point, I aborted the 496 in favor of a 468 via a forged steel 425 crank that was offset ground to Chevy rod journals at 4.24" stroke. I still used the 7.1 rods and CP pistons that a 496 would require.
From what I understand, the nodular iron/"cast steel" cranks still have a bunch of flex. The only real way to reduce it is a well designed full girdle that ties the main caps to the pan rails. Large-ish oil clearances help, but aren't the absolute cure.
Second hand experience is from a bracket racer in Jersey. He broke several Eagle cranks, and I think he may have just gone back to traditional N cranks- not sure.
Another big problem is rod and piston weight. A long time gearhead coworker once told me: "The problem with Oldsmobiles is that they have big, heavy rods and big, heavy pistons." He's not wrong.
Forged cranks are more fatigue resistant due to the change in grain structure from forging. Sub zero tempering (cryogenic, freezing) can also improve grain structure. Tuftriding/nitriding adds a hard surface and might contribute to hardness/strength. Camshafts and crankshafts are tow items that would benefit from Tuftriding/nitriding in today's world.
Strength is more dependent on the material hardness and alloys. This is why Grade 8 bolts are stronger then Grade 5.
Yes , that may be an avenue to pursue for me. , maybe nitrading the crank. Thanks
Ive used the eagle 4.5" crank in a couple of 496 builds. one was 14:1 with a big roller cam and steel rods, the other was a 10:1 street engine flat tappet making about what you plan on making. both are still in one piece with lots of runs and street miles on them.
they are not turning a lot of RPM's. maybe 6500 max for the one and under 6k for the street engine. they both have main cap support, thats a must which you need to have if you want it to live.
the eagle cast steel crank has a higher carbon content than iron cranks which is why they can call them steel.... heres the tensile strength of some crank material
cast grey 70,000 to 80,000
cast nodular 95,000
factory forged 10xx series 100,000 to 110,000
cast steel 105,00 to 110,000
5140 forged 115,000
41xx series forged 120,00 to 125,000
4340 series forged 140,000 to 145,000
notice the tensile strength of the factory 10xx forging and the 5140 are very similar to the cast steel...but the forgings are much stronger because they are less brittle and have higher elongation properties
the only thing i found with the eagle cranks i used was their main and rod dimensions were right at the high side. which meant i couldnt get the clearance i wanted using standard bearings. so i had them ground under to my dimensions and used .010' bearings. im not sure if they fixed that but it was a know problem if you wanted more clearance
i know of a few 496's running hard with the factory nodular crank...done right and nitrided, they can work
Lots of good stuff here, So it looks like the Cast steel is not as bad as some say.
Thank you,
[QUOTE=joe_padavano;1394655]There is truth to this. The material property that governs inherent stiffness is called the Modulus of Elasticity (also known as Young's Modulus). Most steels (cast, forged, billet - all pretty much the same) have a modulus around 29 x 10^6 PSI. Grey iron has a modulus anywhere from 10 x 10^6 to 23 x 10^6, depending on the specific composition. Ductile iron runs about 24 x 10^6. By comparison, aluminum runs about 10 x 10^6 PSI, so aluminum girdles and main caps are really worthless unless they are so massive that the section properties overcome the lower stiffness.[/QUOTE
I appreciate the information. I will need to read up on some of this to fully understand . Thank you
I was going to say the same thing but you beat me to it. Nitriding will add a hard case to the surface but it will also build up material so the part you get back will be slightly larger than the part you sent out. Any heat treating process can alter geometry by changing internal stresses so the dimensional stability can be altered - especially with non-uniform cross-sectional parts (think crankshaft!).
thats in the range ,, but every crank and treating facility is different.
the last one I had done,, we ground it .001” under my specs accounting for the growth,, which was ok before on the other cranks
but after the snout and rear flange grew more. I had to hone the I.d. of the damper to get it on and the flywheel inner diameter was cut so it could slip on. Both ends of the crank grew more than the journals.
this is the last one I had nitrided. A stroked 330 crank which grew more on the snout and flywheel flange
Last edited by CANADIANOLDS; January 3rd, 2022 at 02:53 PM.
thats in the range ,, but every crank and treating facility is different.
the last one I had done,, we ground it .001” under my specs accounting for the growth,, which was ok before on the other cranks
but after the snout and rear flange grew more. I had to hone the I.d. of the damper to get it on and the flywheel inner diameter was cut so it could slip on. Both ends of the crank grew more than the journals.
this is the last one I had nitrided. A stroked 330 crank which grew more on the snout and flywheel flange
Sounds like it was laid down and smaller parts placed near the center of the crank, which shrouded the journals. The ends grew more because they were in the open. Its the shop loading the furnace with parts and uneven flow in the nitriding atmosphere. Just my two cents worth.
Sounds like it was laid down and smaller parts placed near the center of the crank, which shrouded the journals. The ends grew more because they were in the open. Its the shop loading the furnace with parts and uneven flow in the nitriding atmosphere. Just my two cents worth.
I’ve done 4 or 5 BBO Strokers, last one made 585/645.
For your application I wouldn’t waste the money on nitriding. What I WOULD do however is balance it internally. That’ll help reduce crank flex. Should only take a couple of slugs in each end.
Then grind the mains .010, use CB542 HXN rod bearings (.001 more clearance) and you should be fine.
Fleming - not sure why your coworker told you the Olds aftermarket stuff was still heavy. The 7.100 rods are BBC ones and don’t weight much more than Olds stock rods, if at all. A good aftermarket 455-488 rotating assembly is lighter than the stock stuff, by a bunch. A typical bobweight for either a stock stroke or Stroker BBO is about 2200gr, give or take. Stock 455 rods and pistons normally run about 2450.
I'm not sure he has the right info.
Last edited by cutlassefi; January 3rd, 2022 at 05:43 PM.
I’ve done 4 or 5 BBO Strokers, last one made 585/645.
For your application I wouldn’t waste the money on nitriding. What I WOULD do however is balance it internally. That’ll help reduce crank flex. Should only take a couple of slugs in each end.
Then grind the mains .010, use CB542 HXN rod bearings (.001 more clearance) and you should be fine.
Fleming - not sure why your coworker told you the Olds aftermarket stuff was still heavy. The 7.100 rods are BBC ones and don’t weight much more than Olds stock rods, if at all. A good aftermarket 455-488 rotating assembly is lighter than the stock stuff, by a bunch. A typical bobweight for either a stock stroke or Stroker BBO is about 2200gr, give or take. Stock 455 rods and pistons normally run about 2450.
I'm not sure he has the right info.
This is great news to hear others have used this kit with success. I have no issues with rebalancing the crankshaft, how ever, would this not require a different crank shaft? I thought the counter weights on the crank shaft differ from internal and external balanced?
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by CANADIANOLDS
Ive used the eagle 4.5" crank in a couple of 496 builds. one was 14:1 with a big roller cam and steel rods, the other was a 10:1 street engine flat tappet making about what you plan on making. both are still in one piece with lots of runs and street miles on them.
they are not turning a lot of RPM's. maybe 6500 max for the one and under 6k for the street engine. they both have main cap support, thats a must which you need to have if you want it to live.
the eagle cast steel crank has a higher carbon content than iron cranks which is why they can call them steel.... heres the tensile strength of some crank material
cast grey 70,000 to 80,000
cast nodular 95,000
factory forged 10xx series 100,000 to 110,000
cast steel 105,00 to 110,000
5140 forged 115,000
41xx series forged 120,00 to 125,000
4340 series forged 140,000 to 145,000
notice the tensile strength of the factory 10xx forging and the 5140 are very similar to the cast steel...but the forgings are much stronger because they are less brittle and have higher elongation properties
the only thing i found with the eagle cranks i used was their main and rod dimensions were right at the high side. which meant i couldnt get the clearance i wanted using standard bearings. so i had them ground under to my dimensions and used .010' bearings. im not sure if they fixed that but it was a know problem if you wanted more clearance
i know of a few 496's running hard with the factory nodular crank...done right and nitrided, they can work
I never understood why people stroke Olds 455s, the engine is so cylinder head limited as is (4.250 stroke.) On a performance car I'am constantly try to move the power up.
I never understood why people stroke Olds 455s, the engine is so cylinder head limited as is (4.250 stroke.) On a performance car I'am constantly try to move the power up.
Not everybody is like you, thank God. Which begs the question, why are you here?
I never understood why people stroke Olds 455s, the engine is so cylinder head limited as is (4.250 stroke.) On a performance car I'am constantly try to move the power up.
1. Because everyone is not building a drag car.
2. Adding cubes is easier (cheaper) to make higher peek numbers on a dyno.
3. Your still an 🐓🍭
Instead of asking a bait question why don't you try and explain cylinder head capacity to CI and it's effect on RPM and power.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by Duh
1. Because everyone is not building a drag car.
2. Adding cubes is easier (cheaper) to make higher peek numbers on a dyno.
3. Your still an 🐓🍭
Instead of asking a bait question why don't you try and explain cylinder head capacity to CI and it's effect on RPM and power.
Honestly I've never seen a 496 with production heads on this forum make good power on a verified dyno or run hard in the car, now if theres some exceptions I'd like to hear about them. I have seen NHRA stock 455 Olds, and that means Q-Jets, stock cast-iron intakes, stock lift flat tappet cams, factory type pistons, stock type pan, run under 10.50 @ 3650 pounds NA.
I just can't see running that stroke, but I'd never try to talk some one out of doing it that isn't a customer, I just think the factory type stuff can offer excellent performance.
Last edited by VORTECPRO; January 5th, 2022 at 03:21 PM.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by cutlassefi
So as usual you opened a can of worms then bailed on answering the question. Nice.
Lets see if you'll answer this question: Seems like at least 10 years min I've been on this forum and not ONE time has (ANY) of your customers ever had one of your engines to the drag strip, which I find very interesting especially after questing the dyno data on these 455 strokers you built and tested on Matt Scranton's dyno. But never the less one would think in 10 years there would be at least one example validating your power claims, but it never happens. Now there is members on here that do race their street cars, but not one of them has one of your engines..........my question: The guy with the white early 70s 442 race car, why did he not run the engine you built for him in that car? And please correct me if I'am wrong, but I think I heard some where there was a discrepancy over the HP numbers?
I never understood why people stroke Olds 455s, the engine is so cylinder head limited as is (4.250 stroke.) On a performance car I'am constantly try to move the power up.
Patience grasshopper, patience….it will come to you in time 😎
Lets see if you'll answer this question: Seems like at least 10 years min I've been on this forum and not ONE time has (ANY) of your customers ever had one of your engines to the drag strip, which I find very interesting especially after questing the dyno data on these 455 strokers you built and tested on Matt Scranton's dyno. But never the less one would think in 10 years there would be at least one example validating your power claims, but it never happens. Now there is members on here that do race their street cars, but not one of them has one of your engines..........my question: The guy with the white early 70s 442 race car, why did he not run the engine you built for him in that car? And please correct me if I'am wrong, but I think I heard some where there was a discrepancy over the HP numbers?
How about answering Duh’s question first.
Last edited by cutlassefi; January 6th, 2022 at 04:49 AM.
First off I did not ask a question (no question mark) I made a statement. I have my own preference on the subject.
There are pros and cons to both a long stroke and short stroke. I like to build with a goal in mind. Once I know the goal (performance, budget, time frame, usage, ect..) I map it out. If building a drag motor it's biggest bore with the shortest stroke necessary to achieve the goal. Getting a car down track is more about getting the most amount of power to the wheels over a period of time. This is why I always say peek numbers mean nothing.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by Duh
First off I did not ask a question (no question mark) I made a statement. I have my own preference on the subject.
There are pros and cons to both a long stroke and short stroke. I like to build with a goal in mind. Once I know the goal (performance, budget, time frame, usage, ect..) I map it out. If building a drag motor it's biggest bore with the shortest stroke necessary to achieve the goal. Getting a car down track is more about getting the most amount of power to the wheels over a period of time. This is why I always say peek numbers mean nothing.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by fleming442
Is there? Do tell.... I've heard there's minimal difference despite conventional theories.
A big bore short stroke 2 valve engine always make more power, less frictional losses and the big one: the bigger bore accommodates bigger valves. Thats why as far as production 455s go a Buick 455 will usually get on a 455 Olds, only because of the bore size combined with the shorter stroke.
A big bore short stroke 2 valve engine always make more power, less frictional losses and the big one: the bigger bore accommodates bigger valves. Thats why as far as production 455s go a Buick 455 will usually get on a 455 Olds, only because of the bore size combined with the shorter stroke.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by CANADIANOLDS
Patience grasshopper, patience….it will come to you in time 😎
Well....when you run quicker/faster than 9.29 @ 142.29 NA @ a verified 3600 pounds with a 496 inch production headed, production blocked 10.7 compression Olds on a real 10 inch tire through the mufflers, you'll get all the credit from me-but good luck on that...............
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by fleming442
got any proof?
Well I can compare my F/SA 315 HP NHRA stock 10.67 compression 455 Buick with cast iron intake and Q-Jet and .398 lift hyd flat tappet cam, 2.005 Intake valve in my stock cast iron heads to your 455 Olds combination. Not sure where your at now, but I've run 10.70s @ 3650 pounds.
Another comparison: In NHRA stock the 1970 W30 455 Olds run in D/SA which I've seen some 10.40 runs
In NHRA stock the 1970 stage 1 455 Buick runs in C/SA one class lower than the W30, but I've seen 10.00 from that combination
Bottom line: I'am not a Buick fan, but its bigger bore does have an advantage, I don't know if you can say the production Buick head is better, but you can get a bigger valve in there, hopefully you will look at this objectively. In the near future when I get caught up my plan is build a 455 Olds and run it in my Buick, it won't be any thing hi dollar just mainly production parts, but I will be looking to run 10s.
Last edited by VORTECPRO; January 6th, 2022 at 06:32 AM.
So, that would be a "no".
I was talking about a back to back comparison of 2 engines with the same displacement, cam, heads, etc. and the only difference being the bore and stroke to achieve said displacement. Your drag strip pissing contest has too many variables.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,719
Originally Posted by fleming442
So, that would be a "no".
I was talking about a back to back comparison of 2 engines with the same displacement, cam, heads, etc. and the only difference being the bore and stroke to achieve said displacement. Your drag strip pissing contest has too many variables.
Actually that test has been done, but not with a Olds, I can find it if your interested.
January 2nd, 2022, 05:25 AM
