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Old 09-28-2006, 03:31 PM   #316
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Quote:
Originally Posted by MugenDrew
There are two things going as the air temp goes up. Yes the engine temp will rise as air temp increases, but not as rapidly as the engine will go rich do to the lessening of the air density. Cold air more oxygen=more fuel, warm air less oxygen=less fuel. Each cycle of the piston requires a certain amount of metered fuel and air, as the tires get smaller there will be more given cycles over the same distance so more fuel will be consumed. What I have noticed is there is a point where the roll out has become to small for the track due to tire wear and the engine starts running hot like a 40-60 degree jump up in temp. At this point any attempt to adjust the needle richer results in a huge drop in temp and the engine can not be tuned becuase the needle has become way to sensitive. Put tires on it and its rite back to where we started. Look at the roll out chart starting with like 75mm rears,look at the roll out for first and second. Follow the chart down to like 72-71mm and you'll see that to maintain the same roll out\ its as easy as going up one tooth on each pinion. Roll out chart...
I feel like I was changing the gearing to account for tire wear to keep the same distance traveled per revolution of the engine as you are stating. So you are saying that I should have been leaning out the engine to account for less oxygen from the air getting warmer?

Now that brings up another question. Are you saying that as the air gets warmer and there is less oxygen per a certain volume of air, like every molecule is expanding that is making up the air? I will still use the same volume of air and fuel if I keep the same roll out and if I didn't change the high end needle. The worst thing that should have happened was a colder running engine which could have been happening because I never checked. But that should not make me run out of fuel earlier correct?
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Old 09-28-2006, 03:58 PM   #317
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I dont have a roll out chart at work.Are you sure on the tire diameter. Yes air just like everything else expands and contracts. So 1cu.ft. of air at 60 deg. will have a lot more of everything in it than 1cu.ft. of air at 100 deg. There is a fight going on between the cooling systems ability to get rid of heat and the heat that combustion is making. Once again the guy was partially correct in telling you that your engine was going to run hotter. How ever combustion temp is the predominant factor here.
So you need top dog power and if the engine went fat(rich) it would have been less responsive and making less power. Still trying to run as fast as you can your soft engine was letting you get on the throttle earlier and for Longer durations at wide open with out the chassis getting out of control.
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Old 09-28-2006, 08:46 PM   #318
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I am not sure on the role out. I was saying that I was trying to compensate for the tire wear by changing spurs and pinions at differant times to try and keep the role out like it was before the tires got smaller. I don't think that the engine ever ran cooler then 220deg. It would probably never shift if it ran any cooler.The only thing that I can say is that I will have to try leaning the engine out next time. Thanks

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Old 09-29-2006, 06:42 AM   #319
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Yeah this may have gone to deep.... When in doubt lean it out.
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Old 09-29-2006, 09:27 AM   #320
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That's what one of the guys here says the fix for everything is to turn it to the right.
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Old 09-29-2006, 11:07 PM   #321
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Im about buy a new MRX4-R after owning an MRX4 for a couple of years. I have been told there is actually an updated MRX4-R version 2 kit or something and just want to find out if this is true and what are the different parts in the updated MRX4R compared to the MRX4R? I couldnt find out any info using the search.
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Old 09-29-2006, 11:14 PM   #322
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My MRX4 is set for 2morrow. See you guys at the event.
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Old 09-30-2006, 02:26 AM   #323
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Quote:
Originally Posted by PRospeked
Im about buy a new MRX4-R after owning an MRX4 for a couple of years. I have been told there is actually an updated MRX4-R version 2 kit or something and just want to find out if this is true and what are the different parts in the updated MRX4R compared to the MRX4R? I couldnt find out any info using the search.
The MRX4-R ver.2 is the 4-R with the optional hard chassis and different front uprights. You can see the details of it on mugenseiki.co.jp
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Old 09-30-2006, 04:10 AM   #324
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Quote:
Originally Posted by Corse-R
The MRX4-R ver.2 is the 4-R with the optional hard chassis and different front uprights. You can see the details of it on mugenseiki.co.jp
Optional hard chassis has no further milling underneath the engine, am I right ?
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Old 09-30-2006, 04:59 AM   #325
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Quote:
Originally Posted by asw7576
Optional hard chassis has no further milling underneath the engine, am I right ?
Yep... the chassis is this:

http://www.mugenseiki.co.jp/mugen/h0474-e.htm
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Old 09-30-2006, 01:59 PM   #326
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Thanks R.
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Old 10-01-2006, 01:14 AM   #327
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Mistake me if I am wrong guys....I would think that a stiffer chasis would make the rear rotate more, meaning to a certain degree give less rear traction. However, Mugen says the option chasis increases traction. I may be over simplifying things, but I usually equate stiffer settings in the rear (springs, swaybar, etc) loosens things up when you have to much rear bite. So I am now confused that this new stiff chasis makes more traction. Someone please assist with an explaination.
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Old 10-01-2006, 01:36 AM   #328
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Sometimes everything with these cars arent logical. They do go against the grain in concepts & theory sometimes...Unexplainable...
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Old 10-01-2006, 02:33 AM   #329
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Quote:
Originally Posted by Lil Paul
Mistake me if I am wrong guys....I would think that a stiffer chasis would make the rear rotate more, meaning to a certain degree give less rear traction. However, Mugen says the option chasis increases traction. I may be over simplifying things, but I usually equate stiffer settings in the rear (springs, swaybar, etc) loosens things up when you have to much rear bite. So I am now confused that this new stiff chasis makes more traction. Someone please assist with an explaination.
Haven't tried the hard chassis, but seems give more traction at the expense of having a car with more brute reactions. Sometime ago wanted to try one of these (and in fact I have it on the toolbox) but been quite busy so couldn't test it.
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Old 10-01-2006, 04:58 AM   #330
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I'm definately getting that new chassis. My BONE STOCK MRX4 was TOO light and came upto 2475 or so when it had to be 2525 minimum. I was like WTF?! So after decorating it with tire weights it legal however with some bumps n crashes some flew off. I need to use that Gorilla glue my bro in law has.
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