Lightning Sprint/Minisprint tech question
 

MALS is considering a simple way to check engine compression ratios without pulling the head. Anyone have a system that is usable? We have found charts with factory cc's listed and have possibly figured a way to inject premeasured amounts Marvel Mystery Oil in through the plug while at TDC. Then extract the biggest part before replacing the plugs and creating a "hydraulic" situation. A minute amount of MMO shouldn't harm a motor when refired. Questions are..........Do they consider cc with the spark plug in place? How much would .005-.010 in head milling effect the stock cc? Has anyone considered this as a viable way to check compression ratios? Obviously this would be done AFTER bore and stroke have been verified. If someone could call me or email be with some input, I would really appreciate it. We are experimenting to see if we can use this as part of our tech system. Thanks in advance........Phil Heavelow (913) 371-5152 or jmillwright@kc.rr.com

You guys allow aftermarket pistons right?

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Re: Lightning Sprint/Minisprint tech question
 

We allow stock configuration aftermarket pistons. Presently we have a 240 psi max on the compression to work with. I have been told manipulation of valve timing might present a false reading though. To me........compression reading is a compression reading. But we are looking for another method to verify that motor has a stock compression ratio without a major effort to find this out. We check weight, all tranny gears, bore and stoke, compression, bore scope observation for excessive valve relief and fuel. We also can check to make sure the cams have stock lift. If anyone has any experience with this please feel free to contact me. Thanks again.

Re: Lightning Sprint/Minisprint tech question
 

I guess that's what I really like about "stock" engines, no real way to spec them, and be certain you've caught everything someone can do to a "stock engine", ask Joe Gibbs. Measure the bore and stroke, and as far as I'm concerned, that's it, unless you want to work all night and the next day, teching engines, these things are so borderline, another .010 off the block makes it a hand grenade looking for a place to explode anyway, that puts the piston/deck at about .020, which is almost a certain piston/head crash. JMHO! Bob

Re: Lightning Sprint/Minisprint tech question
 

Originally Posted by openwheel44:
We allow stock configuration aftermarket pistons. Presently we have a 240 psi max on the compression to work with. I have been told manipulation of valve timing might present a false reading though. To me........compression reading is a compression reading. But we are looking for another method to verify that motor has a stock compression ratio without a major effort to find this out. We check weight, all tranny gears, bore and stoke, compression, bore scope observation for excessive valve relief and fuel. We also can check to make sure the cams have stock lift. If anyone has any experience with this please feel free to contact me. Thanks again.

Hi Phil

Guess you guys are still chasing your tails with that guy with a funny sounding engine running off and hiding from the rest of the racers?

Honest Dad himself:6::6:

The issue is all aftermarket pistons have altered domes, you can put just as much compression on oem with the right cam timing and a mill.

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Re: Lightning Sprint/Minisprint tech question
 

Hi Dad......Naw......not chasing him or them anymore. We are finally getting things controlled here it seems. Pretty equal playing field and the guys are doing great. Now.....both MALS and MLS are utilizing the same motor rules. We were just trying to come up with a better and quicker way to check actual compression since things can be "sorta" manipulated to give false readings.

TQ29m........we are simply trying to come up with a few basic checks to "convince" racers to not step outside the box on stock motors. We do not want to enforce a major teardown and inspection. We just would like a have simple workable procedures in place to check obvious points where HP can be gained. I am sure someone can work around even these checks and cheat the system. Can't stop everything. But it still amazes me after all my years in racing different classes that someone would intentionally cheat his fellow competitor and be able to live with himself. When you have no honor.....that must not be a problem?

So......someone with some insight..........it this cc check a total waste of time or does it have some validity? Someone shoot some holes in it if there are any. One of my concerns is the viscosity of the 5w Marvel Mystery Oil changing enough in a warm motor that there might be some "leak by" of oil. That tells me the procedure needs to proceed as rapidly as possible. Also carbon build up on the guys running gas might be an issue.

Re: Lightning Sprint/Minisprint tech question
 

Phil - I have a gauge that screws into the spark plug hole. Is that what you are looking for? That would check compression......but then you said something about cc's. Wouldn't a bore and stroke check cc's?

Re: Lightning Sprint/Minisprint tech question
 

Originally Posted by Bradleyracing86:
The issue is all aftermarket pistons have altered domes, you can put just as much compression on oem with the right cam timing and a mill.

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Phil

Like Andy said valve timing does have a lot to do with cranking compression pressure. Longer cam duration (RACE CAM) and and or closing the intake valve Later in the timing event (RETARDING CAM) will lower the cranking compression. It can't make any compression until the intake valve closes at slow cranking speeds. The AMSA tried compression checking many years ago and found it didn't work.

Actual compression ratio depends on two measurements. The total volume of the cylinder measured at bottom dead center including the volume of the combustion chamber to the bottom of the plug hole. Then you need to measure the volume at top dead center all the way up to the bottom of the plug hole. Divide the first reading by the second reading and you get compression ratio. Just measuring the Volume at TDC only probably won't get what you are looking for. Also the cylinder has to be perfectly vertical (you would have to hang car from a crane). I bought a 300cc graduated cylinder 10 years ago to try this out. Valves opening and closing and in-trapped air are your big problems. I was able to measure displacement with this set up by only using only part of the power stroke and a known stroke measurement taken mechanically.

You have a bore scope already, a JE or Wisco piston does not look like a stock piston, they are not supposed to, the machine work is much better, the crown of their piston is not like the stock one's because they all raise the CR just a little, a good reason for buying an aftermarket piston, for that reason one would be hard pressed to find an after market piston with a stock CR.

The best way I know to tell you how to spot an engine with altered compression ratio is to observe the top of the piston. Almost all 4 valve M/C pistons have a little round spot machined into the piston just below the spark plug. They also have 2 lines going across the piston crown cutting the valve relief on the top of the piston, the distance from the little round machine spot to the lines on the valve relief will get closer as you raise the crown of the piston and the compression ratio.

All you need to check a head for milling is a 6 inch caliper, remove the valve cover find an exposed portion of the head where it meets the block, measure from that spot to the machine surface for the valve cover and the milled head will stick out like a trd in the punch bowl.

Frankly I can not understand why a group would allow after market pistons and be worried about compression ratios.

If this guy is still bothering you guys, what I would do is go in the infield set up two cones one at entrance to turn #1 and one at the exit of turn #2. Have someone clock him between the two cones only, and then have them clock the next fastest guy, is there a difference in their times?

Honest Dad himself:6::6:

Re: Lightning Sprint/Minisprint tech question
 

Chris...........we have a compression gauge system but thanks. Some have convinced me to NOT totally rely on that motor compression test due to valve timing manipulation. We are trying to simply check the cc's of the combustion chamber after we have verified bore and stroke are stock. We have the factory spec on the chamber cc's to most motors/years with only a few to go. This way the correct cc of 5W oil could be injected at TDC. We have to determine the exact level that factory spec considers. I am assuming with the plug in place but no one has verified that yet. I can test the theory on my stock ZX-10 and my stock R-1 to see where the pre-determined oil amount is meant to come out and go from there. Just looking for a fairly simple way to check compression other than with a gauge. We will have the plugs out and at TDC at some point anyway. I already have the accurate syringes, oversized needles and suction device to extract the oil when we are done. If the oil rises above a specific level or comes back out the spark plug hole....................."You got some splain'n to do Lucy!" I just was looking for someone to shoot holes in this idea so I can sleep a nights again and quit thinking about it.

Re: Lightning Sprint/Minisprint tech question
 

While Marvel Mystery Oil would be a good choice, most tech is done with either ATF, or diesel injector test fluid, as far as I know, both are pretty much used as the Industry Std. The problem with much of anything besides a bore and stroke ck gets expensive, and the cc by bore and stroke is also an Industry Std, why make it harder on yourself. There is another method, that utilizes the "swept volumn" of the cylinder, which is what Nascar uses in it's initital after the race checks, before they actually do a teardown, and measure the bore and stroke, but that SV testing equipment is expensive, difficult at times to get consistant readings, requires the valves be disabled on at least one cylinder, which means a lot of work on a twin cam engine, and still leaves a lot of doubt as to if it was done correctly, and how accurate it was. If you want to keep it simple, you can do a cc ck, or a bore and stroke ck, and visually do a cam timing ck, and keep on moving, anything else will require taking the motor apart, and running off the owners, there are so many ways around a compression ck it isn't funny, and again, not of much value, as these engines run at such hi RPM, even a low compression ck at cranking speed is of little value, I think you are on a witch hunt, trying to keep or establish a "level" playing field, it isn't all motor. I don't have a dog in this hunt, but have built race engines for years, and motors are motors, some are just better than others, and better at different times, even on the same night, I'd keep it as simple as possible, to keep the racers happy, amongst themselves, no one wants their motor torn down in a dirt track enviornment, even if it is someone elses. JMHO! Bob

Re: Lightning Sprint/Minisprint tech question
 

Dad..........always appreciate your input. Enlightening. I will educate myself on the top of the piston and the things you mentioned. I have noticed the machined spot on the top of the piston and the valve reliefs when using a bore scope but how do you measure that spot in relation to the two lines you referred to with confidence?

Didn't realize that "supposedly stock configuration" pistons slightly raised the compression. At least enough to make any difference in performance. Individuals have complained they can't get certain stock pistons and are forced to go to aftermarket. That is the main reason we accept them. Right or wrong. And then.....that is why we want to verify combustion chamber volume while at TDC. Do whatever you want piston wise.....stock or aftermarket.......mill the head to save it.......whatever..........but that head better take the correct amount of oil at TDC when you get done or you have a problem. I just want to know if this is a truly workable system. Different motors and different years have a range of cc volume. From 21.2 cc all the way up to 23 cc. Now........is that oil to the bottom of the spark plug hole or the top? How far out of plumb can the cylinders be and not create an air pocket that prevents oil from filling the chamber? I will test my info on my two motors and see where it comes out for now.

Re: Lightning Sprint/Minisprint tech question
 

Originally Posted by openwheel44:
Chris...........we have a compression gauge system but thanks. Some have convinced me to NOT totally rely on that motor compression test due to valve timing manipulation. We are trying to simply check the cc's of the combustion chamber after we have verified bore and stroke are stock. We have the factory spec on the chamber cc's to most motors/years with only a few to go. This way the correct cc of 5W oil could be injected at TDC. We have to determine the exact level that factory spec considers. I am assuming with the plug in place but no one has verified that yet. I can test the theory on my stock ZX-10 and my stock R-1 to see where the pre-determined oil amount is meant to come out and go from there. Just looking for a fairly simple way to check compression other than with a gauge. We will have the plugs out and at TDC at some point anyway. I already have the accurate syringes, oversized needles and suction device to extract the oil when we are done. If the oil rises above a specific level or comes back out the spark plug hole....................."You got some splain'n to do Lucy!" I just was looking for someone to shoot holes in this idea so I can sleep a nights again and quit thinking about it.

When we CC a head we remove it from the engine place it on a level bench upside down with the spark plug installed, place a plexiglass cover over the combustion chamber and poor a light oil through a hole in the cover until it fills up and into the hole without any entrapped air, the #'s you have were probably achieved this way. It's awfully hard to get rid of that air without rocking the engine back and forth. Like bleeding your brakes. A good spit is 10 CC's. You are measuring drops in a very unfriendly environment.

Been their done that.

Honest Dad himself:6::6:

Re: Lightning Sprint/Minisprint tech question
 

Phil

Your phone # doesn't work.

Honest Dad himself:6::6:

Re: Lightning Sprint/Minisprint tech question
 

TQ29m.......All good and valid points. I have been around racing long enough to realize and agree with all you have said.

However.......our area group decided we need to so something to insure we were all on as level a playing field as we could get when it comes to stock versus "built" motors. Cost controls is the thing driving this issue. Plus, someone not stinking up the show consistantly. People can tolerate being out driven and out setup but no one likes to be extremely out motored in a supposedly "stock" class. We are adults and know that certain motor might be better and even a particular batch of the same motor might be better. We are combating the obvious here though. Built motors. The racers spoke, MALS is trying to listen and do something to police some of this. Everyone is hoping most of these procedures will not need to be used on a weekly basis but we all agree, we need some workable procedures in place in case something needs to be addressed. Something to keep the honest a little more honest.

And no..........no one wants a teardown at the track. That is why we are investigating simpler ways to obtain certain usable pieces of information as easily as possible. If this is going to NOT achieve the desired results or any useful information......that's what I want to hear from people that know and I will go waste my time on some other procedure.

Re: Lightning Sprint/Minisprint tech question
 

Dad........did you call (913) 371-5212 (office) or my cell at (816) 223-1009?

Re: Lightning Sprint/Minisprint tech question
 

Originally Posted by openwheel44:
TQ29m.......All good and valid points. I have been around racing long enough to realize and agree with all you have said.

However.......our area group decided we need to so something to insure we were all on as level a playing field as we could get when it comes to stock versus "built" motors. Cost controls is the thing driving this issue. Plus, someone not stinking up the show consistantly. People can tolerate being out driven and out setup but no one likes to be extremely out motored in a supposedly "stock" class. We are adults and know that certain motor might be better and even a particular batch of the same motor might be better. We are combating the obvious here though. Built motors. The racers spoke, MALS is trying to listen and do something to police some of this. Everyone is hoping most of these procedures will not need to be used on a weekly basis but we all agree, we need some workable procedures in place in case something needs to be addressed. Something to keep the honest a little more honest.

And no..........no one wants a teardown at the track. That is why we are investigating simpler ways to obtain certain usable pieces of information as easily as possible. If this is going to NOT achieve the desired results or any useful information......that's what I want to hear from people that know and I will go waste my time on some other procedure.

DAD, I know what you are trying to achieve, I just don't think it's possible in the real world, a "stock" engine, in my HO, is just too much to keep in spec, I would think you would have to "give" a little, for parts stack up, as they call it in the industry, you know, a little plus and minus in most cases, but I guess it's a lot like the guy said, when asked if his new girl friend was pregnant when they started dating, yeh, but just a little bit. Bob!

Re: Lightning Sprint/Minisprint tech question
 

Originally Posted by TQ29m:
DAD, I know what you are trying to achieve, I just don't think it's possible in the real world, a "stock" engine, in my HO, is just too much to keep in spec, I would think you would have to "give" a little, for parts stack up, as they call it in the industry, you know, a little plus and minus in most cases, but I guess it's a lot like the guy said, when asked if his new girl friend was pregnant when they started dating, yeh, but just a little bit. Bob!

Bob----My little brother, an artist had a better saying : "PERFECTION IS TOO DAMNED DELICATE".

From racing go-karts you know how "ANAL" some people and rules can get, I've been DQ'd over being .001 out of spec. We are racing some pretty high tec stuff now days and they don't leave a lot of room for improvement.

People like me and you like to play and rich folk just like to pay and there is always someone wanting to protect both of us from ourselves.

Keep the rules simple and easy to check Bore, Stroke, cam lift and valve size, heck you could even check for stock appearing shaped piston crown, but worrying about compression pressure and even compression ratio gets to be too involved about a modification that won't net much Horse power.

Mini-Sprinters need to worry more about the fuel that is being used. Methanol is not nor has it ever been the power enhancer that race groups think should require a racer to add 25-50 pounds on to their race car to keep things on the up and up. However some of this off the shelf and maybe slightly doctored $20.00 a gallon race gas should be considered an enhancer with a 5% to 10%+ Hp improvement guaranteed by the company's that sell this stuff. This is equal to about a "20 HORSEPOWER" improvement over stock HP ratings on our little engines. This is more than you could ever get with just a set of high compression pistons****** go figure.

And some of this stuff has even been proven to cause "CANCER"!!

Honest Dad himself:6::6:

Re: Lightning Sprint/Minisprint tech question
 

The one thing I have noticed over my few years of racing is!!!!

THE FASTEST*** "CHEATER"*** MOTORS ARE ALMOST ALWAYS IN THE> BEST DRIVEN> BEST HANDLING CARS ON THE RACE TRACK.;);)

Honest Dad himself:6::6: