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Engine Displacement Testing (and how to work around it)

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Engine Displacement Testing (and how to work around it)

Postby HOGJOB » Wed Jun 22, 2005 5:19 pm

This past weekend the officials at the local track decided to tear down a few cars in the sportsman class. (358ci max, 2bbl carb, prod heads, pump gas, open cam & valvetrain) In the past, the have always just pump tested the motor with a tool that threads into the spark plug hole and has a floating piston to show the mass of air being moved while the engine was cranking.

This time, they surprised everyone with a new toy that I had never seen before. This tester was a blue box that had to be plugged into wall current, and required a high pressure air source (they used a CO2 bottle). Like the pump test, the device was threaded into a plug hole and they asked that the engine was manually turned until the compression stroke began for that cylinder (intake valve closed) The device had two hoses that ran to the "cigar shaped" spark plug fitting. To perform the test, they entered the temperature of the head into the machine, and it clicked and bled off some pressure and told them the engine was legal. Unfortunately, they wouldn't share the results, or tell us how close we were to being illegal.

Common sense tells me that they were measuring the volume of the combustion space, but does anyone know what this device is called and exactly how it works?

What would stop someone from running a cam with a later IVC number to hide some extra cubes?
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Postby maxracesoftware » Wed Jun 22, 2005 8:32 pm

i've heard of a device called a "Whistler"
but this was used to checkout Compression Ratio

what you are describing sounds very close to Whistler description ?

without backing off on the Intake rocker to get zero lash or clearance at BDC , i don't know how they could measure the Cylinder volume correctly
Last edited by maxracesoftware on Thu Jun 23, 2005 4:37 pm, edited 1 time in total.
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Postby HOGJOB » Thu Jun 23, 2005 4:22 pm

Yep, that's the one. It took a while to find it.

http://www.katechengines.com/corporate_ ... istler.php

The way the description sounds, it needs a measurement at bdc and tdc. If I recall correctly, they took the measurement abdc when the intake valve was closed. Depending on the IVC timing, it could make a 377 look more like a 358... well maybe not that drastic, but you could definately hide a small overbore. I heard them mention that the machine was brand new.... I wonder if they were using it incorrectly.
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Postby maxracesoftware » Thu Jun 23, 2005 4:38 pm

Thanks for the Link :)
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PipeMax and ET_Analyst for DragRacers
http://www.maxracesoftware.com
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PipeMax v3.98   http://www.maxracesoftwares.com/forum/v ... f=14&t=249
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Postby learner » Thu Jun 23, 2005 5:27 pm

I had a friend running a 427 in a boat. I did a freshen up hone on loose cylinders running trw's. The piston clearance was .012". It was pumped at 408". This was only supposed to run three races. He ended up running something like 9-10 before one of the skirts broke.
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Postby highVE » Sat Jun 25, 2005 5:17 pm

the product your are describing, is without a doupt a Katech Whistler. A friend of mine who is also a race engine builder owns one. he builds alot of cirlce track 2bbl stuff. it is around $3000 for that item. (to the best of my knowlege)
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