ATVridinMaNiAc Posted November 4, 2012 Author Report Share Posted November 4, 2012 If you would have ran it a little longer you would have only had to trench one side for a 10 mill crank It came like this i didnt run it, and thanks everyone for the help good info, definitely running it. Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 4, 2012 Report Share Posted November 4, 2012 Crankcase volume does affect the performance of a motor. This little bit of damage won't hurt anything at all. Man, you and spurdy are sooooo far from the truth it hurts. You both need to go do some homework. Crankcase volume DOES affect performance. The bigger volume in the case is going to change the velocity of the fluid as it travels from the case to the transfers. Basic fluid dynamics! Now, the damage in this guys pics is probably not going to affect his performance because the damage is not significant. Try this... Run a stock stroke crank and cylinders on a set of cases that have been bored and stroked for a 10, 14, or even a 16mil setup. I garuntee you that you will notice a difference. I know, because ive done it! I ran a stock stroke on a set of 10mil cases and it sucked! If what you guys are saying was the case, you could increase the case volume infinitely, and the only thing that would matter is the stroke of the piston going up and down. Think about it like this... Take a straw from mcdonalds and blow air into a ziplock bag. Now take that same straw and blow air into a garbage bag. Now tell me that the velocity of volume increase in those two bags is equal just because the staw used in both cases is the same. There are engines from top running 2stroke moto GP bikes back in the 70's that actually had custom stuffer setups made to decrease case volume to help performance and increase velocity in the transfers. Jared Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 4, 2012 Report Share Posted November 4, 2012 Man, you and spurdy are sooooo far from the truth it hurts. You both need to go do some homework. Crankcase volume DOES affect performance. The bigger volume in the case is going to change the velocity of the fluid as it travels from the case to the transfers. Basic fluid dynamics! Now, the damage in this guys pics is probably not going to affect his performance because the damage is not significant. Try this... Run a stock stroke crank and cylinders on a set of cases that have been bored and stroked for a 10, 14, or even a 16mil setup. I garuntee you that you will notice a difference. I know, because ive done it! I ran a stock stroke on a set of 10mil cases and it sucked! Jared Thats so wrong jared. You, me, blair, jennings know nothing! Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 4, 2012 Report Share Posted November 4, 2012 Maybe it would help hearing it from calvin pollet, or tim bond... LOL Heres a very detailed conversation about case volume and pressure. The concersation was started by calvin pollet, the guy who designed the cub cylinders, cheetah, DM, puma, sphinx, etc. His comments are also backed up by tim bond, owner of titan racing and one of the most intelligent guys in this industry. http://www.planetsand.com/forums/ubbthreads.php/ubb/showflat/Number/1070379/Searchpage/5/Main/41/Words/case+volume/Search/true/Re_Crankcase_pressure_theory_o#Post1070379 Quote Link to comment Share on other sites More sharing options...
BigRed350x Posted November 4, 2012 Report Share Posted November 4, 2012 Heres a direct quote from calvin... " Will iteffectthingsiftheCCRistoolow or too high?....yes it will. Although the difference in a tight crankcase and a loose crankshaftarea is not as big of a difference in volume as one would think. The area that seems to get overlooked IMHO is the base gasket area, if you put a .100 spacer plate, (say you had just put in a piston with a taller deck height, or a longer rod without using a shorter deck piston), the amount of volume is NOT just the volume in the bore....it isthe total volume of the bore area, PLUS the volume of the "slice" of the transfer tunnel area on each side.....multiplied by thethickness of the plate, (or the amount that the cylinder was raised). Sometimes the extra volume is a help, sometimes it hurts performance." Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted November 4, 2012 Report Share Posted November 4, 2012 getting good... Quote Link to comment Share on other sites More sharing options...
spurdy Posted November 5, 2012 Report Share Posted November 5, 2012 Fair enough, but we weren't comparing different motors, we were comparing what he started with to what he has now. Obviously if it where the difference between a 350 or a 390/421, to something like a 535 the volocity would change. But we wern't comparing that scenario. You can't take a post like this and change the context and use that logic to call someone out. In the context of this post I stand by what I originally stated. SP Quote Link to comment Share on other sites More sharing options...
camatv Posted November 5, 2012 Report Share Posted November 5, 2012 oh lord. the lowerend cranking compression on almost all motors that are "normal" is not going to be so affected by miniscule rod damage or other issues .. so i actually agree with spurd on this one. so what. 350cc 4mill most 10's etc etc are not going to be adversly affect by crank compression as som HUGE cc motor on a tiny lowerend OR a tinny cc motro in a HUGE lowerend case area. like your 350cc in 10 stroke set up. how much CC did you loose running that 350cc crank in a trenched case vs the loss in cc intake of the motor's lowerend charge.. that was significant. yea i can see how it sucked. in those situations i would start looking at low end comp. i cannot think of anyone or heard of anyone running a comp gage on their transfer ports to measure lowend comp. although it has been done. if you actually knew what the cranks looked like back when blair or jennings or whatever was looking at or even read more than just a few pages in those books you would realize why it was such a huge issue back in the early 70"s YES 70"s and why it was talked about. also in those books there is a lot of talk about how it is not AS important now that the factory had redesigned the crank webbs to take up space adn increase the bottom end cranking compression. unless you are building some crazy wacko engine and have had issues with it running well then ccr is not as important as it may seem. OR building on a set of cases some HUGE engine they were not designed to handle as the cp cylinders seem to do o so often. this of COURSE is just my opinion. to ME in my opinion if you are overly concer'd about cranking comp you should also have titanium rods for reasons the GP bikes had them.... along with flywheel weights.... and stop complaining about howmuch a ( fill in the high quality part ) costs. only thing post's like this can do is start about 90 uneeded posts asking about cranking compression.. and if their 350cc needs the cases stuffed or the transfers filled back in.... stuffers are cool. though.. not saying i dont use them in certain spots.... or in other words.. Quote Link to comment Share on other sites More sharing options...
oldskool Posted November 5, 2012 Report Share Posted November 5, 2012 They can go in either side. You only need one to maintian bearing position. SP Thanks a lot Quote Link to comment Share on other sites More sharing options...
ATVridinMaNiAc Posted November 5, 2012 Author Report Share Posted November 5, 2012 Didnt expect this thread to turn into this but, very good info regardless haha. Quote Link to comment Share on other sites More sharing options...
camatv Posted November 5, 2012 Report Share Posted November 5, 2012 wow i re read some of that post on planetsand. that was LONG time ago. you did realize that started life in 2002 as far as a topic. its 10+ years old now.. still relevant but at least there are some really good minds contributing to that post. i only read a few pages and brought back a lot of memories... its really sad there is just not the same kind of conversations going on today.. to hard to separate the people that might know the people that should know and the people that are full of shit these days.. i love that comercial with the chick who believe's that anything on the net has to be true no matter what. ( she read that on the net rember!) Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 5, 2012 Report Share Posted November 5, 2012 We weren't saying the rod damage was going to affect it. We were correcting false information. Something that needs to happen more often. Quote Link to comment Share on other sites More sharing options...
spurdy Posted November 5, 2012 Report Share Posted November 5, 2012 We weren't saying the rod damage was going to affect it. We were correcting false information. Something that needs to happen more often. You were being a Dick. Something needs to happen less often. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 5, 2012 Report Share Posted November 5, 2012 Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 5, 2012 Report Share Posted November 5, 2012 Couldn't give 2 fucks or a fat rats ass what you think of me. Quote Link to comment Share on other sites More sharing options...
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