Hi-Po Flathead Bottom End Strengthening help.

[38flattie]

Hello,

I'm new here, and hoping to gather some info and usable advice. I have a Cadillac flathead, 4.625" stroke, 3.55" bore, that puts out 570Hp and 544 ft/lbs torque, at 5500 rpm and 14.2 psi boost.

I'm looking for ways to further strengthen the block, without having to go the expensive, time consuming act of a 5 main setup.The block already has billet mains, a very heavy crank girdle, and a crank girdle snout support.

How can I make the bottom end stronger still? Pin the mains to the block? Cryogenics? Redesign an exotic 4 bolt main?

I'd post some pics of the bottom end, but can figure out how to get this done!

Thank you in advance!

[Stan Weiss]

Below the box you type your message is an "UPLOAD ATTACHMENT" Button. If you still have trouble uploading them, email them to me an I will post them.

Stan

srweiss at erols dot com

[38flattie]

Thanks Stan!

MAINS BEFORE LINE BORE.JPG

MAIN CAPS-GIRDLE.jpg

BlockWithBoltsX1.jpg

[38flattie]

One more.

RearCap_InBlockX1.JPG

[PackardV8]

I have a Cadillac flathead, 4.625" stroke, 3.55" bore, that puts out 570Hp and 544 ft/lbs torque, at 5500 rpm and 14.2 psi boost.

Good start and great numbers for a flat Cad. From the photos, you've done most of what is possible.

One thing I recollect from Ford flathead V8 days is three main bearings are never going to get strong enough to resist stupid. If you don't want to go to five mains, do the best you can to run smart with three. Lessen their load wherever you can.

1. Billet crankshaft - if the crank is sufficiently strong, three mains will support a lot of horsepower. The Novi V8 was a three-main 160"-180" V8 and made more than 800 horsepower.

2. Meticulous balance of all the rotating/reciprocating engine and driveline parts. One old guy whose four-bangers ran well claimed a heavy flywheel and heavy front damper were beneficial for three mains at Bonneville.

3. Computer controlled crank-triggered ignition. Good spark at just the right time will lessen the load. Wandering timing, cross-firing, retard not following boost curve and detonation are your worst enemies with a weak crank and three mains.

4. Control the coolant temp. With that 4.625" stroke, there is a lot of bore friction. A few hot spots will not be good. I'd go with coated piston skirts and tops. One of the faster Fords also coated the combustion chamber of the heads and the valve tops.

5. Meticulous line hone and cylinder hone with deck plate. Again, precision lightens the load.

6. Best practice dry sump system with lots of oil pressure.

Run long, fast and prosper.

jack vines

[38flattie]

I have a Cadillac flathead, 4.625" stroke, 3.55" bore, that puts out 570Hp and 544 ft/lbs torque, at 5500 rpm and 14.2 psi boost.

Good start and great numbers for a flat Cad. Is this the detailed build over many pages on HAMB?

Yes it is.

One thing I recollect from Ford flathead V8 days is three main bearings are never going to get strong enough to resist stupid. If you don't want to go to five mains, do the best you can to run smart with three. Lessen their load wherever you can.

1. Billet crankshaft - if the crank is sufficiently strong, three mains will support a lot of horsepower. The Novi V8 was a three-main 160"-180" V8 and made more than 800 horsepower.

It has a Crower custom billet crankshaft and rods. Stock mains were 2.49", and it now has 2.75" mains.

2. Meticulous balance of all the rotating/reciprocating engine and driveline parts. One old guy whose four-bangers ran well claimed a heavy flywheel and heavy front damper were beneficial for three mains at Bonneville.

This, too, has been done.

3. Computer controlled crank-triggered ignition. Good spark at just the right time will lessen the load. Wandering timing, cross-firing, retard not following boost curve and detonation are your worst enemies with a weak crank and three mains.

This is next on my list-will do it after Speedweek!

4. Control the coolant temp. With that 4.625" stroke, there is a lot of bore friction. A few hot spots will not be good. I'd go with coated piston skirts and tops. One of the faster Fords also coated the combustion chamber of the heads and the valve tops.

Russ Meeks at Finishline Coatings is one of our sponors. He coated the pistons, skirts, valves and chambers.

5. Meticulous line hone and cylinder hone with deck plate. Again, precision lightens the load.

This was done by Jeff Fowler, Fowler Engines, in Colombus, OH

6. Best practice dry sump system with lots of oil pressure

. I'm running a Barnes 9713 dry sump system, with Moblie Racing 0W-50 oil.

Run long, fast and prosper.

jack vines

I posted my response above in bold italics.

Jack, thanks for the advice!

[DrillDawg]

Seeing you only have 6 studs holding this engine together, is there anything to be gained looking into the stud clamping force, stud material, necked down studs, ect.

DD

[Stan Weiss]

With the deep block Is it possible to add a cross bolt to the mains?

Stan

[SchmidtMotorWorks]

Can you post some pictures of the crank?
How are the counterweights sized relative to the parts connected to it?
With that much open space getting the mass of the CWs right is important. Balancing alone won't do that.

[38flattie]

The crank weights are huge. The factory crank had bolt on weights, and the crank weighed 91 lbs. The Crower billet crank weighs in just over 90lbs

LowerEnd-Complete.JPG

crowercrankXx.jpg

[DrillDawg]

Can't believe that you didn't give that crank the aero treatment and maybe coat those huge counterweights to shed some oil.


DD

[mtkawboy]

Correct me if Im wrong but I dont think you can use the computer controlled ignition control in the vintage engine classes, at least it cant control it going down the course. My friend Doug runs the Salt Cat II straight 8 Buick lakester at Bonneville in XXO and I know he cant

[38flattie]

Correct me if Im wrong but I dont think you can use the computer controlled ignition control in the vintage engine classes, at least it cant control it going down the course. My friend Doug runs the Salt Cat II straight 8 Buick lakester at Bonneville in XXO and I know he cant

That's correct-you can't run it in vintage engine classes, in vintage bodied cars.

Look at Ron Mains' Flatfire.

[SchmidtMotorWorks]

The crank weights are huge. The factory crank had bolt on weights, and the crank weighed 91 lbs. The Crower billet crank weighs in just over 90lbs

That's an interesting crank. Was any analysis/engineering done to design the CWs or was it an educated guess?
Given the positions of the CWs, if it dynamic balances it probably isn't too far off.
It would be a couple days work to model that though because I don't have anything to reuse that is anything like that.
Sorry I couldn't be of more help.

[38flattie]

Stan, I like the idea of cross bolting the mains!

The crank weights are huge. The factory crank had bolt on weights, and the crank weighed 91 lbs. The Crower billet crank weighs in just over 90lbs

That's an interesting crank. Was any analysis/engineering done to design the CWs or was it an educated guess?
Given the positions of the CWs, if it dynamic balances it probably isn't too far off.
It would be a couple days work to model that though because I don't have anything to reuse that is anything like that.
Sorry I couldn't be of more help.

It balanced out well. I paid Crower to design the crank, so I sure hope the engineered it right!