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 Post subject: Re: LP motor testing
PostPosted: Thu Jul 05, 2018 5:42 am 
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Spark plug length compared to tester threaded end that screws into the head, I bet is shorter than some of the spark plugs used. We alway use NGK plugs, and with LP1275s we always use the "P" plugs, which mean projected tip, meaning longer. We do alot of ported street heads here at the shop and use max CR target of 10.0 to 1, we found out, say if we put the wrong spark plug in the head for cc testing, like non "P" spark plug it could net a extra 1-2 ccs. If you look a most LD testers, or compression testers, the the thread insert that goes into the spark plug hole is almost always shorter than the spark plugs used in those engines, if the whistler is like this, then there ya go, there is your low readings.

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 Post subject: Re: LP motor testing
PostPosted: Thu Jul 05, 2018 9:38 am 
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https://dk1xgl0d43mu1.cloudfront.net/us ... 1432153407

Looks like way too much room for human variables to consider this anything other than a pre-teardown guess...

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 Post subject: Re: LP motor testing
PostPosted: Thu Jul 05, 2018 6:42 pm 
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after all the jokes and criticism is it possible I can't tell the difference between a full prep E-P 1600 Miada and an LP F-P 1600 Miata exhaust noise?.
Or is it that they sound a lot more alike than they used too? And after all the years in SCCA without filing any protests, I will not be doing it now. I have always thought the club is responsible for enforcing the rules they write. But I do expect them to be able to do so accurately.
rick haynes


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 Post subject: Re: LP motor testing
PostPosted: Thu Jul 05, 2018 7:32 pm 
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Location: Atlanta, Ga
I have always thought the club is responsible for enforcing the rules they write. But I do expect them to be able to do so accurately.[quote][/quote]

I take exception to this statement. SCCA does not write the production car LP rules. Production by its' nature has always had limitations. Almost all performance rules were written(requested) by prod drivers as is most of the performance rules in the GCR. Drivers request the prep rules(letters to CRB) and they are either approved or not.

Then, they are published and it is up to tech only at the Runoffs to verify compliance. Most of the time, it is up to your fellow competitors to listen/think/watch/guess/etc if you are playing by the rules you and others wrote. Only at the Runoffs and now some Majors does tech do invasive procedures to verify compliance.

PS. We have several different spark plug screw in adapters for the whistler to match the plug you are using. Suggest everyone cc their motors before the Runoffs. See my comment about build sheets.

Good to see Craig Chima today at Pitt Race Complex. If you are here, stop by the V8 Road Race Series compound and say hello.

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 Post subject: Re: LP motor testing
PostPosted: Fri Jul 06, 2018 3:19 am 
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rick haynes wrote:
after all the jokes and criticism is it possible I can't tell the difference between a full prep E-P 1600 Miada and an LP F-P 1600 Miata exhaust noise?.
Or is it that they sound a lot more alike than they used too? And after all the years in SCCA without filing any protests, I will not be doing it now. I have always thought the club is responsible for enforcing the rules they write. But I do expect them to be able to do so accurately.
rick haynes


It's been noted that overlap can make a big impact on exhaust note.
Level 2 cars are restricted in valve lift.
How would you design a cam if you wanted to maximize power, but had a low lift limit?

Since I started in IT, where there was rarely threat of anything beyond weight being checked, I have always been prepared to protest a car that I believed to be outside the rules. Never had to write the paper, but I have had the discussion with another driver letting him know to expect it unless he chose to move to a class that aligned with his modifications. It worked out fine.

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 Post subject: Re: LP motor testing
PostPosted: Fri Jul 06, 2018 3:34 am 
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FP Racer wrote:
…..Then, they are published and it is up to tech only at the Runoffs to verify compliance.

Jim - The question was asked whether the compression ratio of the winner is checked by CC'ing the combustion chamber regardless of what the whistler read. I didn't see an answer to that.

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 Post subject: Re: LP motor testing
PostPosted: Fri Jul 06, 2018 4:44 am 
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Ron Bartell wrote:
FP Racer wrote:
…..Then, they are published and it is up to tech only at the Runoffs to verify compliance.

Jim - The question was asked whether the compression ratio of the winner is checked by CC'ing the combustion chamber regardless of what the whistler read. I didn't see an answer to that.

I haven't seen that done in probably 10 years, and even then it was more of a fiddly inaccurate mess than an improperly opeated Whistler test.

Put me also in the camp of "It's the responsibility of the competitors to ensure the compliance of their fellow competiton." If you've got suspicion, talk to the person about it, and if they're "less than amicable" to do so, then there's a very well laid out process in place to force their hand. If you're right, you get your money back, they get what comes along with being labeled a cheater, and our racing is better for it. If you're not right, well then you know and can stop the "what if's".

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 Post subject: Re: LP motor testing
PostPosted: Fri Jul 06, 2018 5:22 am 
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kruck wrote:
Put me also in the camp of "It's the responsibility of the competitors to ensure the compliance of their fellow competiton."
I would agree with that during the regular season. At the Runoffs it is the responsibility of Tech to ensure that the winning car is legal. That is why the winner is torn down. If Tech is using a system for checking compression that is not accurate or is not trusted by the competitors then we can't be sure that the car is legal. CC'ing the motor when it is apart would put all of the speculation about whistler accuracy to bed, and in my opinion should be part of the teardown process for LP motors. If it was a cluster f**k in the past, then figure out a way to do it better.

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 Post subject: Re: LP motor testing
PostPosted: Fri Jul 06, 2018 5:30 am 
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Location: Atlanta, Ga
Answer to cc'ing in prod at Runoffs is no. However, there is a but involved. We were preparing to cc post race after whistler failure and found something else which made DQ for sure. Also found a GTL car at Runoffs well over and he had mismatched pistons from one motor to another trying to make the race after blowing up two motors in qualifying. Results was way to much compression.

As I recently said, I've whistled a lot of cars including well over 200 Spec Miatas. Recently whistled a SM that was .3 over max and it was cc'ed. Guess what the cc determined? Yep, it was .3 over the max allowed. I whistled several of my own BLM motors and then cc'ed them and whistler was correct. I've whistled a lot of pro built motors and asked the builder what CR was prior to whistling and had it be dead on. Also whistled several and found them to be well over at the ARRC. CC'ing found problems such as wrong pistons.

Final note is no one will ever be penalized by the whistler reading. it is just a tool to narrow down what else we need to check. But, as an engine builder, I would never ignore my calculations to do additional prep to a motor. Need I say more?

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 Post subject: Re: LP motor testing
PostPosted: Mon Jul 16, 2018 9:28 pm 
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"Final note is no one will ever be penalized by the whistler reading. it is just a tool to narrow down what else we need to check."

I don't think any more need be said about how inaccurate and unreliable the current way the club checks LP motors.

rick haynes


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