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Thread: Crank Tech
04-21-2012, 12:15 PM #46
I accidentally started this post as an edit to your post above Ricky, apologies for mis-mousing the edit post button.
Virtually all forged ModMotor cranks available from anyone today are OEM Ford units made by Kellogg for Ford. In fact if you look at the crank cheek between #1 main and #1/#5 rod journal you will see the Ford Logo forged right into the crank.
The crank shops that try to tell you it is their own custom forging are both BS 'ing you and don't deserve your business. When the cranks are in fact Kellogg forgings they quickly gets to a commodity status and like tomatoes at the supermarket you want to buy the cheapest tomatoes that are the same size (stroke). I would go shopping for a good used crank and don't forget manual trans Mach I's got the same crankshaft.
BTW although the crank material is advertised by the aftermarket crowd as 4340 it is not! It is a modified C38 micro alloy that is similar to but not 4340. Additionally the cranks are very soft inside. The OEM hardening process is paper thin. When I went through the modification process on the Kellogg shaft in my recent post on crank snout fixes click here =>Crank Snout Fix we had to nitride the entire crank before I was willing to use it in my engine.
While you are looking at that post look at the "stock" crank picture. It is actually an aftermarket crank advertised as the usual double throw down ultra blitz racing crank. Take a close look at the cheek of the crank between #1 main and the #1 rod journal. It has a Ford Logo forged into the crank at manufacture. This is a Kellogg crank at a premium price that a major vendor is parading around as a custom forging. The crank even has the under cut fillets right from Kellogg that Ford specs on these cranks. Aftermarket crank shops always use full radius filets on their own manufacture cranks - it's stronger.
The crank your link points to is advertised as having full radius fillets on the rods and mains. If it does it is truly a custom ground forging. Whether or not it is real 4340 or micro alloy requires additional investigation. The easy way to determine if it really does have full radius fillets is to request close up pics of the rods and mains. The full radius fillets will become immediately visible. Ask for a photo with the cheek between #1 main and #1 rod journal visible so you can look for the Ford Logo in the forging. If you do not see the Ford Logo ask if the crank is a Chinese forging. Even with full radius fillets (if it has them) you still have a crank with a tender snout.
If you want to use an OEM crank and don't mind doing a little work, you can use a Coyote crank. FRPP sells them for about $225-$250! Spend a little money at a crank shop to finish the crank for our mod motors and you will be lots of dollars ahead of the game with a mini stroker that will bring you to about 289 cubic inches - how cool is that? Remember though you still have a crank with a tender snout.
As you already know from reading the snout fix post, if it were me again I would just go to a billet crank from the get go. It is unquestionably the best solution and with hard ModMotor parts like cranks all but non existent today and when you do find them they can be so-so, the billet crank solution makes a lot of sense.
Last edited by eschaider; 04-21-2012 at 12:20 PM.
04-21-2012, 12:28 PM #47
Great info once again ed. I can't thank you enough. Does the coyote crank offer any benefits other than 8 cubes? A 289 would be cool. My dad would get a kick out of that! What mode are required to put it in a teksid? Are the 5.0 stroker (3.75 stroke) cranks made well?
04-21-2012, 01:50 PM #48
The 5.0 cranks are the same Kellog forging the 4.6 uses except ground with small block Chevy rod journal sizes (not a bad idea) at a stroke of 3.75 or 3.8 I can't remember which and all else the same. One of the two strokes is aftermarket and one is Saleen. This is the same crank Ford used in the Saleens. It will give you 297 cubic inches with a std bore. Ford claimed 302 for the magic of the number.
I tend to shy away from the strokers because of how far they pull the edge of the wrist pin below the bottom of the bore at BDC. The flip side of that coin is there are a lot of Saleens and stroked mod motors using the crank - successfully. Personal preferance in the end probably.
The Coyote crank is a bit longer in the snout than a 4.6. It is also worth while checking into rear flange dimensions. Ford mounted the crank position sensor wheel on the back of the Coyote crank between the crank and the flywheel. I don't know if they changed the thickness of the rear flange for the reluctor wheel or not. If they did you can run a Coyote reluctor wheel back there. If they didn't you just bolt up the flywheel and either way you are ready to go.
The front of the crank is a little longer than our mod motor crank to accommodate the TiVCT hardware. The crank grinder would have to bring the stop for the lower crank gear back to the same dimension as a 4.6 crank. The incremental increase in snout length will do you good in terms of locating the damper and preventing movement of the damper.
FWIW the Coyote oil pump is a higher volume pump than the Cobra pump to take care of the TiVCT hardware's appetite for oil. If you use this pump your oil pressure will go up and you ought to look into a higher volume pan.
The 5.0L Coyote crank does not use Chevy journals for the rods. Ford's Saleen crank does. The after market '5.0L' cranks for mod motors, available as either 3.750 or 3.800 stroke, also use small block Chevy rod journals. Both the Saleen and the aftermarket 5L stroker cranks use a 5.850 long rod. Some Eagle crank strokers use a 5.950 long rod. Eagle Specialty Products 5.950 rod is, I believe, unique to them. A standard bore block with a 3.75 stroke crank displaces 297.3 cubic inches and a 3.800 stroke displaces 301.2 cubic inches.
Last edited by eschaider; 04-21-2012 at 08:49 PM. Reason: spelling
04-22-2012, 03:46 AM #49
- Join Date
- Feb 2006
Ed, who would I send a crank to for nitride treatment?
You can PM me if you want.
04-22-2012, 09:42 AM #50
Here is a picture of the eagle crank I found on the web.
04-22-2012, 11:38 AM #51
- Join Date
- Jul 2006
- San Jose, CA
04-22-2012, 12:48 PM #52
04-22-2012, 11:13 PM #53
04-22-2012, 11:25 PM #54
Last edited by eschaider; 06-12-2016 at 05:37 PM. Reason: Updated Calculator with additional engine configs
04-23-2012, 11:17 AM #55
Usually your crank shop has nitriding facilities available to him. It is better to do it through a crank shop because when they come back from the nitriding process they require a clean up and final polishing. The appearance of the crank right out of the nitriding process is a dull grey everywhere including the journals. The crank shop cleans the crank and then polishes the journals so it looks and works like a crank again.
04-23-2012, 08:56 PM #56
- Join Date
- Apr 2003
- Montgomery County, PA
A 5.4 Shelby block has a 6.062" cylinder length.
Just did one today.
I have 5 2011 GT 500 blocks I just bored last month waiting for me to do the liquid nitrogen bit and I think they are the same length.
I could check all the 4.6 stuff if you like, I have most all variations this month on the floor.
Except the Teksids, they are all buttoned waiting delivery.
04-23-2012, 09:10 PM #57
04-24-2012, 06:53 AM #58
04-24-2012, 07:35 AM #59
The liquid nitrogen is to shrink the sleeves so they can be put inside the block with an interference fit. It also helps to evenly heat the block prior to assembly. Hyland discusses this in his book.
04-25-2012, 02:04 AM #60
Apologies for the late response Michael.
Thanks for the length data and offer. When I did the measurements I only had 4.6 blocks to measure. Two were Ford's Windsor blocks and one was Hyland's. The 5.4 sleeve length will make it possible to build a more accurate version for the 5.4 also. I inferred a cylinder length based on a standard crankcase and the 5.4 deck height. I'll check tomorrow and post up the calculated figure I used for the 5.4.
If you have a 4.6L Romeo block that you could measure, it would be helpful as a check against the other 4.6 blocks. I didn't have a 4.6 Romeo available when I built the spreadsheet. The Teksids were my other missing data point. But I think I have a measurement coming for them.
Last edited by eschaider; 04-25-2012 at 02:11 AM.
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