Use Torque Plate or Not

Lil Red

Lil Red

Lil Red
Apr 3, 2010
20
0
1
Calgary, Alberta
I'm getting conflicting responses from local engine builders as to the need to use a torque plate when boring/honing a Duramax engine. The argument I'm getting against, is that the block is so beefy and rigid that block distortion from bolting/torqueing on the heads is very minimal or non-existent. My reason for asking is that I recently tore down my engine after very little run time (less than 10,000 km's and 12 passes on the 1/4 mi) because it was suffering from excessive blowby (high crankcase pressure). Inspection of the cylinders show scuffing of the walls in all bores and in random areas around the whole circumference and length of the cylinder. So far we have just pulled the heads. The block is coming out this week and will pull the crank/rods/pistons to determine piston/ring condition. This LB7, 7240 lb truck has ran 11.008 @ 128.88 mph so is making north of 900HP at the wheels. The blowby became so severe that the turbo shaft seals bypassed oil into both the exhaust and intake (all three turbos were resealed - twice). The pistons are 40 over Mahle forged with Hellfire rings. This engine was NOT torque plated when bored/honed.
I'm sure I'll get a lot of response on this.
 
duramaxzak

duramaxzak

Wanna be puller!
Nov 22, 2008
2,431
14
38
Minnesota
I used a torque plate on my block when it was machined, .020" Forged Mahle pistons, no blow by problem's.

I think using a torque plate can only have positive effect's, so why would you not use one?!
 
Lil Red

Lil Red

Lil Red
Apr 3, 2010
20
0
1
Calgary, Alberta
Torque Plate

Ya. I knew what the answers would be. Also, I know better. Got talked out of using a torque plate but looking back I should have insisted. Maybe time to look at a different engine builder.
 
IOWA LLY

IOWA LLY

Yes, its really me
Feb 23, 2007
2,275
4
0
I own 2 torque plates. Whenever I have a block machined I insist on both being installed, torqued to whatever it will be assembled at, using arp assembly lube. I also make them install main caps and torque them to spec as well before any machine work is done.

In my opinion this is probably overkill, and simply using one torque plate is probably all that is needed. But I would never ever let a machine shop bore or hone a block without using at least one. They move way, WAY more then most people realize.

The only other thing I can comment on is I have always used Mahle rings. I haven't had blowbackblowby or oil consumption issues. I have never ran hellfire rings so I don't know about them.

Sent from my SM-N920V using Tapatalk
 
Lil Red

Lil Red

Lil Red
Apr 3, 2010
20
0
1
Calgary, Alberta
Torque Plate

Thanks for your input Iowa LLY. I would be interested to know if anyone has performed before and after bore dimension checks, that is, bore and hone with torque plates and check bores in several places, then unbolt the plates and check the bore in the same locations to determine changes. This simple check would confirm the need for the use of torque plates. If I were an engine builder, I would do this and publish the results as a selling point for that service.
 
battlegraduate09

battlegraduate09

Gearhead
Mar 18, 2010
610
0
16
Lil Red said:
Thanks for your input Iowa LLY. I would be interested to know if anyone has performed before and after bore dimension checks, that is, bore and hone with torque plates and check bores in several places, then unbolt the plates and check the bore in the same locations to determine changes. This simple check would confirm the need for the use of torque plates. If I were an engine builder, I would do this and publish the results as a selling point for that service.
Click to expand...

I havent done that on a duramax but i have done it on a chrysler inline 6 about a year or so ago. I done it for an experiment at the company i built motors for because i was working with Mahle for custom ring fitments and ring gap settings.

Obviously if i remembered the differences off the top of my head i would have posted them by now but i do remember the cylinder taper and out of round spots changing drastically from using a "wash and hone" method with no torque plate vs using a torque plate. Both tests done on a sunnen ck21 hot hone machine.
 
Lil Red

Lil Red

Lil Red
Apr 3, 2010
20
0
1
Calgary, Alberta
battlegraduate09 said:
I havent done that on a duramax but i have done it on a chrysler inline 6 about a year or so ago. I done it for an experiment at the company i built motors for because i was working with Mahle for custom ring fitments and ring gap settings.

Obviously if i remembered the differences off the top of my head i would have posted them by now but i do remember the cylinder taper and out of round spots changing drastically from using a "wash and hone" method with no torque plate vs using a torque plate. Both tests done on a sunnen ck21 hot hone machine.
Click to expand...

I hope some engine build/rebuild shops chime in on this subject. I know in some applications (NASCAR engines, for example) that not only is the boring/honing performed with torque plates, but all accessories and brackets are bolted to the block and coolant at raceday engine operating temperature is circulated through the block to simulate thermal expansion.
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
Lil Red said:
I hope some engine build/rebuild shops chime in on this subject. I know in some applications (NASCAR engines, for example) that not only is the boring/honing performed with torque plates, but all accessories and brackets are bolted to the block and coolant at raceday engine operating temperature is circulated through the block to simulate thermal expansion.
Click to expand...

You wont get much info out of them to be honest. They keep a lot of info off the interweb just like trans builders.
 
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