Landracing Forum

Bonneville Salt Flats Discussion => SCTA Rule Questions => Topic started by: SteveM on March 05, 2012, 01:16:31 PM

Title: How is engine displacement directly measured on diesel engines?
Post by: SteveM on March 05, 2012, 01:16:31 PM

I know how to calculate displacement, my question is about how SCTA measures displacement on an IDI (Indirect Injection) diesel engine, assuming that someone has set a record.  There is no direct access to the piston tops, like on most gassers.  Pulling an injector out only gives a peek to the inside of a pre-combustion cup.

Is there some kind of air displacement measuring device that can be attached to a glow-plug hole, or some other similar apparatus? 

This is mostly a curiosity type question that came to me while reading the rulebook last night.

Steve.

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: McRat on March 05, 2012, 01:53:55 PM

The race team is responsible for proving the displacement.

Yes, the SCTA is not well-equipped to do diesel engines via the spark plug method. 

Best method, is that when you're building the engine, to get an SCTA inspector over and record the displacement and seal the engine, then record it in the log book.

Or, after you set a record, you pull a cylinder head.  This can be problematic for some of the late model production V8's where it can be difficult to pull a head without removing the engine.

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: Stainless1 on March 05, 2012, 02:10:54 PM

If you bring an adapter they can connect the air volume measurement tool to and you can disable the valves in the cylinder being measured then I see no reason it cannot be measured by that method.  If you are really close to the break then you will probably need to pull the head just like the gas and fuel guys.
How easy or hard to do isn't taken into consideration.  :|

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: SteveM on March 05, 2012, 02:49:25 PM

Good info.  It would be presuming a whole lot of hard work and good luck to think that I'd be in a position to do a teardown, but at least I know how it works now.

I do have an adapter for both the glow plug hole and the injector hole which could be hooked up to an air volume measurement apparatus.

My plan is to be at 1490 cc's, on a limit of 1524 cc's if I remember right (don't have rulebook in front of me).  That's about 2 percent under the limit.  I assume that would be in cylinder head removal territory.

Are there any SCTA inspectors in the Missouri / Illinois area?

SteveM.

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: Jack Gifford on March 06, 2012, 01:58:42 AM

I think the rule says that within 3% of class limit, bore/stroke measurement must be made (only for a record, of course).

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: jimmy six on March 06, 2012, 10:24:51 AM

Don't know much about diesels but gas engines must pull the push rods or deactivate the valves to use the air pump method. If you are removing a glow plug or some other device in a diesel I would also make sure YOU have made an adapter to screw or hold it in. I believe the air pump hoses were 1/2" ID from thepump to the adapter....Good Luck

Title: Re: How is engine displacement directly measured on diesel engines?
Post by: SteveM on March 07, 2012, 10:22:46 AM

Step 1 - set a record.

Step 2 - pull cylinder head.  My displacement will be too close to the limit to allow for the air pump method.

I think I need to worry more about Step 1, but was just curious about how displacement is measured without dis-assembly.

Steve.