TRX250R.ORG
General => Lounge => Topic started by: mandom250r on May 29, 2014, 05:42:30 PM
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I was just wondering why everyone shows much interest in 363s and not 370s. About two years ago everyone wanted a pro-x 370 so they could be the fastest at the dunes; at least people that i knew. Now everyone seems to have stroker engines, the 344 and 363 being most popular. Is the 370 mostly for drag racing and the 363 more for play/dune? Is there something i dont know? Which one makes more power? are there better port numbers with the +4mm 363? i would just like to compare pro-x cylinders as i know a sphynx would make more power than a 370 pro-x.
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363 is actual displacement of a 370 on it's first bore (78mm bore on a +4 crank). It's just a play on numbers. Kind of like how a stock R engine on its first bore is 246cc actual, yet is called a 250.
I have an ESR 78mm top end on a stock crank. Actual displacement is 344cc, but it's referred to as a 350
I'm not sure there is a straight big bore that can get you to 370cc or thereabouts. As far as I am aware, 350 (344 actual) is as big as you can make an R engine with stock stroke (on first bore anyway). 370's require a stroker crank, +4mm. Unless something has changed
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Also the use of the 4 mil stroke crank from hot rods vs having an oem stroked 5 mil.
Numbers have always been rounded a bit even from the factories. Factory 125 250 450 500 etc are not really that exact cc most of the time.
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yea i know the displacement is always less that what it says but i guess my question is why is everyone going with a +4mm crank and not a +5mm crank?
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Before the new hot rod 4 mil held together I think most "370" were 5 mil oem rebuilds. You can still get a 5 mil made up it is just a lot are going with the new hot rods 4 mil out of the box due to cost and availabilty-turn around time on a good oem crank being stroked.
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but which one makes more power?
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Depends on builder ,tuning ,gearing and rider
Both are fast
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someone needs to get on here and explain what stroke and bore makes what CC
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Most the time a 363 is a sphinx cp setup
78 bore with 76 stroke
When people say 370 most likely its a ProX or Esr cylinder at 78 bore with a 77 stoke
Comes out to 368 cc if memory serves me right
But if u go on the cp industries website u can build a 363 puma aswill
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^^^ here are some calculator links http://trx250r.org/threads/240-calculator-links
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^^^ here are some calculator links http://trx250r.org/threads/240-calculator-links
awesome links!!! ok i got my answers for displacement but i guess i have one more question. Does a +4mm have an advantage over a +5mm?
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Somebody from another site seems to think so....I have run a 5mm stroker crank with a ESR 350 top end for three years and have yet to see a 363 pass me on the track......
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Somebody from another site seems to think so....I have run a 5mm stroker crank with a ESR 350 top end for three years and have yet to see a 363 pass me on the track......
hell yea those are the kind of answers im looking for but i wish they were built by the same builder though
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A 370 is closer to square and is probably a more balanced power than a 363. But I bet it's a negligible difference from that perspective.
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hell yea those are the kind of answers im looking for but i wish they were built by the same builder though
I am running the older ESR cylinder which if I remember right is the old PRO-X cylinder......FTZ ported my cylinder to match the 5mm stroke....I assembled it myself with a few other options....
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I know of one old Honda engine that actual displacement is as advertised.... the legendary ATC350X!! ;)
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Somebody from another site seems to think so....I have run a 5mm stroker crank with a ESR 350 top end for three years and have yet to see a 363 pass me on the track......
That is a horrible analogy. Just because a 363 hasn't passed you doesn't mean jack squat.
I could be on my 363(i'm sure it make mucho power to your setup) and you could be on a stock 250r and still beat me it the style of racing you do.(Rider and experiance being the deciding factor here)
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That is a horrible analogy. Just because a 363 hasn't passed you doesn't mean jack squat.
I could be on my 363(i'm sure it make mucho power to your setup) and you could be on a stock 250r and still beat me it the style of racing you do.(Rider and experiance being the deciding factor here)
Sorry Rupp I have to disagree with you......I highly doubt a stock 250r would even be close to staying with me and it's also nice that you know for a fact that your 363 puts out so much more power than mine...... How about you show up to Ventura Speedway in August and you back up your claim???....I still have never raced there so it would be an even challenge.......This is a friendly challenge....Don't make this into an ugly thread
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Ferrin
I think Rupp was saying is that if he was on his 363 and u on a stock 250r ,depending on where u guys were riding ,u could beat him in certain places or vice versa
Bieng that Rupps bike is setup way more different then urs ,there's certain disadvantages and advantages on both ends
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Sorry Rupp I have to disagree with you......I highly doubt a stock 250r would even be close to staying with me and it's also nice that you know for a fact that your 363 puts out so much more power than mine...... How about you show up to Ventura Speedway in August and you back up your claim???....I still have never raced there so it would be an even challenge.......This is a friendly challenge....Don't make this into an ugly thread
I think you took my post way wrong. Read what Ported R said.
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i thought that simply due to cylinder design, a cp of similar size would make several more HP compared to a equally built pro-x or esr cylinder.
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hey guys i just want to compare a 363 to a 370 thats it. if i had a 363 and a 370 that i could race around the track or in a drag race i want to know which one is faster.
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i thought that simply due to cylinder design, a cp of similar size would make several more HP compared to a equally built pro-x or esr cylinder.
I would say this is true if you have the same porting,pipe, and setup but I would guess a Drag ported esr or prox would more than likey have more than say a dune ported sphynx of the same cc's.
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i thought that simply due to cylinder design, a cp of similar size would make several more HP compared to a equally built pro-x or esr cylinder.
yea lets keep CP cylinders out of this also because we all know they will produce more power
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hey guys i just want to compare a 363 to a 370 thats it. if i had a 363 and a 370 that i could race around the track or in a drag race i want to know which one is faster.
I'm no expert but what I've been told is the rod angle on the 5mm crank is harder on the piston skirts than the 4mm crank, thats really the only differnece that I've heard of.
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yea lets keep CP cylinders out of this also because we all know they will produce more power
i just meticuliously read through ur OP, i see what your saying now i thought when speaking of the 344 and 363 you were speaking in relation to a cp, due to just recently reading arlans post on how you want a stroker to actually use a cylinder designed for the stroker crank: http://trx250r.org/threads/2423-Stoker-Engines
in terms of building a +4 or a +5 prox, im sure the comparisions are negliable, except for the fact that the +5 there is alot of labor involved, compared to the out of the box +4.
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hey guys i just want to compare a 363 to a 370 thats it. if i had a 363 and a 370 that i could race around the track or in a drag race i want to know which one is faster.
ALL things being equal. There is no replacement for displacement.
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you could probably have the same builder build a 363 motor and 370 motor and I bet there will very little if any difference in the 2 motors, the 4mm stroke stroked crank from Hot rod is a tough deal to beat so spending more money for 1mm more stroke may not give you any return on your money.
There is allot more to making a motor run fast than just adding more stroke or bore to a motor.
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would you say that a 363 vs 370 is like comparing it to a short rod vs long rod engine?
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you could probably have the same builder build a 363 motor and 370 motor and I bet there will very little if any difference in the 2 motors, the 4mm stroke stroked crank from Hot rod is a tough deal to beat so spending more money for 1mm more stroke may not give you any return on your money.
There is allot more to making a motor run fast than just adding more stroke or bore to a motor.
Amen to that!
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Ferrin
I think Rupp was saying is that if he was on his 363 and u on a stock 250r ,depending on where u guys were riding ,u could beat him in certain places or vice versa
Bieng that Rupps bike is setup way more different then urs ,there's certain disadvantages and advantages on both ends
Truth be known I'm getting old and I think Rupp would probably kick my butt no matter what we raced....LOL
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I'm glad you made this thread. I do plan on a 370ESR build for a duner. Good info so far
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I'm no expert but what I've been told is the rod angle on the 5mm crank is harder on the piston skirts than the 4mm crank, thats really the only differnece that I've heard of.
Yes the 5 mm stoker rod angle is harder on piston skirts than a 4 mm stroker. ................... but.................a 4 mm stoker rod angle is much much harder on piston skirts than a stock stroke crank. One should not be worried about how hard something like rod angle is on piston skirts if you have the money to spend on any of the aftermarket cylinder kits and related components. Before investing in one of these big bore kits one needs to be aware that any engine with big forged pistons require frequent piston and ring changes.
The big bore kits are hard on everything, bearing pockets, transmissions, clutches, etc. not just pistons. If we used a con rod a mile long it is not going to prevent these big bore pistons skirts and piston crowns collapsing. The problems we have with these pistons is not because of the rod angle, it is because of the lousy design of the forged pistons being made for these kits.
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Yes the 5 mm stoker rod angle is harder on piston skirts than a 4 mm stroker. ................... but.................a 4 mm stoker rod angle is much much harder on piston skirts than a stock stroke crank. One should not be worried about how hard something like rod angle is on piston skirts if you have the money to spend on any of the aftermarket cylinder kits and related components. Before investing in one of these big bore kits one needs to be aware that any engine with big forged pistons require frequent piston and ring changes.
The big bore kits are hard on everything, bearing pockets, transmissions, clutches, etc. not just pistons. If we used a con rod a mile long it is not going to prevent these big bore pistons skirts and piston crowns collapsing. The problems we have with these pistons is not because of the rod angle, it is because of the lousy design of the forged pistons being made for these kits.
Jerry who in your opinion makes the best piston kit for a big bore?????
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^Or some other oem piston?
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which set-up would be best for a drag or duner?
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jerry which of the cylinders do you think you could get the most hp and torque out of?? just wondering??
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Jerry who in your opinion makes the best piston kit for a big bore?????
There are only two that I know of, Wiseco and Wossner. I do not like the piston designs of either one. I call the pistons that both of these companies make for the TRX big bores, "drag racing pistons". Thin skits, thin parallel piston crowns are characteristic piston designs used in ultra high RPM engines that only need to run for seconds at a time and do not have to be designed to dissipate the heat from the crown at the same rate it is being created. A well designed piston can be run wide open when tuned for max power for more that 15 to 20 seconds without the top caving in or blowing through.
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jerry which of the cylinders do you think you could get the most hp and torque out of?? just wondering??
The only cylinder that I have done development on the is CP 330. I have a ESR 330 that I am planning to develop this summer.
Getting the most HP or the most Torque out of an engine is not one of my goals. The engine with the most peak HP will be good for the salt flats. The engine with the most torque will be good for pulling stumps after logging. Maximizing either the torque or power will not win drag races, super cross racing or be good for recreational riding.
There are power curve shapes that are needed for each application. Most dirt racing requires a power curve shape that will produce the most acceleration. A power and torque curve shaped for acceleration needs to look more like a four stroke power and torque curve.
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ahhh thats true. i didnt even think about that. like most ppl i find myself wondering how much hp or torque a quad has and then judge how fast it is from that. thats almost racial profileing now that i think about it. lol
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There are only two that I know of, Wiseco and Wossner. I do not like the piston designs of either one. I call the pistons that both of these companies make for the TRX big bores, "drag racing pistons". Thin skits, thin parallel piston crowns are characteristic piston designs used in ultra high RPM engines that only need to run for seconds at a time and do not have to be designed to dissipate the heat from the crown at the same rate it is being created. A well designed piston can be run wide open when tuned for max power for more that 15 to 20 seconds without the top caving in or blowing through.
I remember back in 1986 the oem pistons from Honda were better because of them being a cast piston. We had problems with Weisco pistons because the were forged ... People would take them to their local machine shop and have their cylinder bored to the Honda manual specs and then bring them to us wondering why their piston seized.....They didn't know because after warm up a forged piston swells more than cast so it needed more clearance...If I remember ARTS pistons were good also for oem as if I remember right they were the one who made the pistons for Honda at the time...
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ahhh thats true. i didnt even think about that. like most ppl i find myself wondering how much hp or torque a quad has and then judge how fast it is from that. thats almost racial profileing now that i think about it. lol
lol its funny cuz its true. i usually look at what pipe and paddles theyre running and judge them from there.
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lol its funny cuz its true. i usually look at what pipe and paddles theyre running and judge them from there.
Exactly, if you are running a FMF I am most likely to go to the next post.
If you really want to know if a 363 is faster than a 370 you would have to have both bikes on the dyno with the same set up... pipe, carb, fuel. Just a little tuning on the dyno can give you another 10 HP.
The main reason we are running 4mil instead of 5 or 6 mil is that the hotrod 4mil has not had the pin moved where as the pin has been moved 1 or 2 mm on the 5 and 6 mil. Its the longevity of the crank and cost factor that guide us.
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Exactly, if you are running a FMF I am most likely to go to the next post.
If you really want to know if a 363 is faster than a 370 you would have to have both bikes on the dyno with the same set up... pipe, carb, fuel. Just a little tuning on the dyno can give you another 10 HP.
The main reason we are running 4mil instead of 5 or 6 mil is that the hotrod 4mil has not had the pin moved where as the pin has been moved 1 or 2 mm on the 5 and 6 mil. Its the longevity of the crank and cost factor that guide us.
sounds good to me lol
yea i guess i would prefer an original plug-n-play part than one that has been machined or modified even though its new
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sounds good to me lol
yea i guess i would prefer an original plug-n-play part than one that has been machined or modified even though its new
Excuse me I meant moved 5 or 6mm. The wedge that is welded in does not give 360 degrees support.
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how much of a difference would it make in terms of the life of a piston due to heat dissipation if you used something like a swain tech heat coating on the top of the piston? I have ran these coatings in 4 stroke combustion chambers on several of my previous 4 stroke drag bikes with great success.
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ALL things being equal. There is no replacement for displacement.
I must agree with you Rupp! This holds true for any type of motor- the only time this statement may not hold true is if a power adder is brought into the equation... On a naturally aspirated motor there definitely no replacement for displacement!!!
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your far better off having 2 or more small displacement cylinders rather than one large on. 250 x2 would beat the pants off a 500 x1 cylinder
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how much of a difference would it make in terms of the life of a piston due to heat dissipation if you used something like a swain tech heat coating on the top of the piston? I have ran these coatings in 4 stroke combustion chambers on several of my previous 4 stroke drag bikes with great success.
Applying the thermal barrier on a highly developed two stroke will drive the engine into instant pre-ignition and then detonation when it comes on the pipe.
The four strokes have twice as much time for the surface of the barrier to cool between power strokes and the thermal barriers do not usually cause a problem unless you have a 15000 + RPM fourstroke.
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I must agree with you Rupp! This holds true for any type of motor- the only time this statement may not hold true is if a power adder is brought into the equation... On a naturally aspirated motor there definitely no replacement for displacement!!!
For poorly developed engines, displacement is an easy way to add power to any two or four stroke engine. A 60 cc leaf blower usually makes more power than a 50 cc leaf blower made by the same company. A Honda stock XR 600 usually makes more power than a stock XR500. A stock 350X usually makes more power than a 250X...and so on.......
It is sad that the statement does not usually hold true for engines that are highly developed and someone just installs a stroker crank and or a big bore kit. Every week someone calls or brings in an engine that had a really good engine combination of pipe/port/carb/head/ignition and now the power is down and or it will not stay together after they went window-shopping on the net. They filled their shopping cart with snake oil and ruined a really good power package with the contents in the shopping cart. The customer reports his new big bore stoker engine has more power down in the 3000 to 5500 RPM range but does not pull has hard or rev like my old 250. I look at the mess and shake my head asking why did you do that to a real good power package?
Grandpa, Dad and Uncle Buford always said there is not replacement for displacement on those flat head ford V8s so it must also apply to the TRX 250R Hondas and all of the other high tech engines. After doing "his research": Looking at 100 other shops on the net that were selling different flavors of the same snake oil he swallowed the hook and bought a big bore piston and stroker crank. I had a friend that is the lead techs at my local Honda dealer install the kit for me. My friend followed the kit instructions. He bored the cylinder for the forged piston and then honed it to the recommended clearance of .0015” with a ball hone. He checked the welded stroker crank for trueness and he worked on it for a couple of hours and finally got true to within .003”. Then we removed the stock air box and the factory intake hose and put a K&N air filter 3” in diameter and 6” long directly on the back of the carburetor so the engine can breath with the added displacement.
It is sad but we all have probably experienced the above scenario. If you have not, you are probably still in those PAINFUL-EXPENSIVE adolescent years of learning about what to do, what not to do or who has a good recipe to build an engine to fulfill your needs.
An engine builder cannot repeatedly build a fast reliable package without first making a lot of mistakes while developing, testing and finding the right recipe (specifications and components). When a good recipe is developed and then it is followed, it will make one powerful and reliable package just like when our mom and grandmothers use a recipe that may have taken years before they "got it right". Many of the shops that sell this snake oil are often at the same experience level of building high performance engines as the customers are who at the adolescent level of just starting to get pimples.
An engine that was developed using the larger displacement during development will almost always run circles around an engine that was highly developed and then the larger displacement as added as an update.
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ahhh thats true. i didnt even think about that. like most ppl i find myself wondering how much hp or torque a quad has and then judge how fast it is from that. thats almost racial profileing now that i think about it. lol
My fastest engines are the ones that i have spent the most testing and development time on. A fast engine can be an accident for some builders but not for me.
When you do a lot of testing and keep detailed records of the test and engine specifications for each dyno or field test, it is possible to go back and build any one of hundreds of different engine packages. If an engine builder has a 1000 dyno runs on a particular year make and model engine, he should have enough information to go back and duplicate the power of anyone of the 1000 dyno runs on another engine. If he does not have enough records to build another engine from specs of anyone of those 1000 dyno runs, he is probably in the category of having an occasional accident.
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My fastest engines are the ones that i have spent the most testing and development time on. A fast engine can be an accident for some builders but not for me.
When you do a lot of testing and keep detailed records of the test and engine specifications for each dyno or field test, it is possible to go back and build any one of hundreds of different engine packages. If an engine builder has a 1000 dyno runs on a particular year make and model engine, he should have enough information to go back and duplicate the power of anyone of the 1000 dyno runs on another engine. If he does not have enough records to build another engine from specs of anyone of those 1000 dyno runs, he is probably in the category of having an occasional accident.
well my man.. your making a strong case to be my next engine builder!! i really like to read your posts. so much info and detail in your answers make me understand what your saying. i can see the hours you put into your work by the words you type. very respectful i must say.
hey were about in phoenix are you located?? my wife and her entire family is from there. she is from glendale- peoria area.
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The old saying of 80% of the power is found with only 20% development and the other
20% of the power is found in the last 80% of developmentis so very true
that is why guys like Jerry Hall ,Mat Shearer, Dennis Packard, Nate McCoy and many other good builders are worth the extra price for their work. you are buying many hours of dyno and/or track time besides the work they are performing.
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The old saying of 80% of the power is found with only 20% development and the other
20% of the power is found in the last 80% of developmentis so very true
that is why guys like Jerry Hall ,Mat Shearer, Dennis Packard, Nate McCoy and many other good builders are worth the extra price for their work. you are buying many hours of dyno and/or track time besides the work they are performing.
So very true