4stroke on 1/10 or 1/8th truck or car
03-09-2008, 03:10 AM
#26
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RE: 4stroke on 1/10 or 1/8th truck or car
a KTM 450 SXF puts 52 hp to the rear wheel in stock form, thats around 60 at the crank, a CR 250 (most powerful peak HP 250 two stroke) put just 44 HP to the wheel stock, quite a large differance, i race dirt bikes myself, and 4 strokes having more bottom end is in no way an advantage as all it doesn is wear you out, but the higher peak HP is a big advantage, 2 two stroke is a lot more freely revving then a 4 stroke regardless of torque in the MX world due to the lower rotating mass in the engine to spin (which there isn't much torque difference at all, a 250 two stroke runs at around 14k RPM making max power at around 12k, 450's run at around 11k RPM making max power at around 10k, modern 4 stroke are all big bore engine, which are not torque monsters)
oh and throttle position results on the data logger on the fuel injection system of ricky Carmichael's RM-Z 450 put him at wide open throttle 76% of the time throughout the 2007 season, we're not on and off the throttle all the time either, through a corner it's full throttle in, pick your line, brake hard, mid corner back to full throttle for the strait, it is constantly a full throttle or hard braking affair until you get tired and can't hold on anymore, much like RC racing, and a lot different to flat track midget car racing.
oh and throttle position results on the data logger on the fuel injection system of ricky Carmichael's RM-Z 450 put him at wide open throttle 76% of the time throughout the 2007 season, we're not on and off the throttle all the time either, through a corner it's full throttle in, pick your line, brake hard, mid corner back to full throttle for the strait, it is constantly a full throttle or hard braking affair until you get tired and can't hold on anymore, much like RC racing, and a lot different to flat track midget car racing.
03-09-2008, 11:00 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
a KTM 450 SXF puts 52 hp to the rear wheel in stock form, thats around 60 at the crank, a CR 250 (most powerful peak HP 250 two stroke) put just 44 HP to the wheel stock, quite a large differance, i race dirt bikes myself, and 4 strokes having more bottom end is in no way an advantage as all it doesn is wear you out, but the higher peak HP is a big advantage, 2 two stroke is a lot more freely revving then a 4 stroke regardless of torque in the MX world due to the lower rotating mass in the engine to spin (which there isn't much torque difference at all, a 250 two stroke runs at around 14k RPM making max power at around 12k, 450's run at around 11k RPM making max power at around 10k, modern 4 stroke are all big bore engine, which are not torque monsters)
oh and throttle position results on the data logger on the fuel injection system of ricky Carmichael's RM-Z 450 put him at wide open throttle 76% of the time throughout the 2007 season, we're not on and off the throttle all the time either, through a corner it's full throttle in, pick your line, brake hard, mid corner back to full throttle for the strait, it is constantly a full throttle or hard braking affair until you get tired and can't hold on anymore, much like RC racing, and a lot different to flat track midget car racing.
a KTM 450 SXF puts 52 hp to the rear wheel in stock form, thats around 60 at the crank, a CR 250 (most powerful peak HP 250 two stroke) put just 44 HP to the wheel stock, quite a large differance, i race dirt bikes myself, and 4 strokes having more bottom end is in no way an advantage as all it doesn is wear you out, but the higher peak HP is a big advantage, 2 two stroke is a lot more freely revving then a 4 stroke regardless of torque in the MX world due to the lower rotating mass in the engine to spin (which there isn't much torque difference at all, a 250 two stroke runs at around 14k RPM making max power at around 12k, 450's run at around 11k RPM making max power at around 10k, modern 4 stroke are all big bore engine, which are not torque monsters)
oh and throttle position results on the data logger on the fuel injection system of ricky Carmichael's RM-Z 450 put him at wide open throttle 76% of the time throughout the 2007 season, we're not on and off the throttle all the time either, through a corner it's full throttle in, pick your line, brake hard, mid corner back to full throttle for the strait, it is constantly a full throttle or hard braking affair until you get tired and can't hold on anymore, much like RC racing, and a lot different to flat track midget car racing.
what makes a 450 bike faster than a 250 on the track (in a drag a 450 would be a little faster then a 250 but not by much, the only reason a 450 is faster in a drag is because the more power and torque so they start in 3rd gear instead of 2nd like the 250) but on the track a 450 can beat a 250 (as long as the rider knows how to ride a 4-stroke) the 4-stroke smooth power and its low end makes them great for flat tracking, and good for hard packed (because of the smooth power) and good for sand (because of the extra power)
03-09-2008, 01:09 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
Well see now our dyno numbers indicate otherwise. Now we run methanol in our enigne's and our 250's are running in the vasinity of 76 hp with a 50mm carb on. With our 125's being Honda RS engine's running in the vascitity of 40-45hp as stated there actually around 136cc's. So that CR must have been one of the older models being pre 96 or a CR that was fairly rich when ran on the dyno. And from experience the 4 strokes have a ton more torque(thats why ween we restart they will beat our 2 strokes) but will fall behind quickly due to the lack of top end. You are correct that the big bore doesnt create the monster torque that a stroker would, but a 4 stroke will always have more torque then a 2 stroke will of the same difference( I.E 125 2stroke vs a 250 4 stroke).
In our wide open races our 125's consistently beat those 250 4 stroke's on both a 1/8th mile track and on a 1/4 mile track. The 250's making around the same hp numbers as our 125's but you got to remember that the 250's have (now not all of them do) around 7 grand into there motors. 3 or 4 of it just being in the head work alone.
But you are correct that it's a lot different to that of flat track racing. But with our Dyno numbers and the results from racing kinda indicate a little different results then what you are saying. By the way we happen to have had a data logger (actually a mychron 6 I believe) log a cr 125(some people still use cr's in the 125 class) that reved over 16,000 rpms with a big bore stroker combo. Now that seems insane but it did, I seen it with my own two eye's.
In our wide open races our 125's consistently beat those 250 4 stroke's on both a 1/8th mile track and on a 1/4 mile track. The 250's making around the same hp numbers as our 125's but you got to remember that the 250's have (now not all of them do) around 7 grand into there motors. 3 or 4 of it just being in the head work alone.
But you are correct that it's a lot different to that of flat track racing. But with our Dyno numbers and the results from racing kinda indicate a little different results then what you are saying. By the way we happen to have had a data logger (actually a mychron 6 I believe) log a cr 125(some people still use cr's in the 125 class) that reved over 16,000 rpms with a big bore stroker combo. Now that seems insane but it did, I seen it with my own two eye's.
03-09-2008, 04:47 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
125cchyperman, bikes have a 38mm carb, and I've seen a 95 CR 125. 96 CR 250, and a 04 CRF450 run side by side and by the same rides (dad and bro) and the 450 would be the winner, unless in a tight track a 125 and 250 could be thrown around easier in there because of weight.
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
03-10-2008, 11:14 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: JB COMP
125cchyperman, bikes have a 38mm carb, and I've seen a 95 CR 125. 96 CR 250, and a 04 CRF450 run side by side and by the same rides (dad and bro) and the 450 would be the winner, unless in a tight track a 125 and 250 could be thrown around easier in there because of weight.
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
125cchyperman, bikes have a 38mm carb, and I've seen a 95 CR 125. 96 CR 250, and a 04 CRF450 run side by side and by the same rides (dad and bro) and the 450 would be the winner, unless in a tight track a 125 and 250 could be thrown around easier in there because of weight.
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
And yeah a newer 450 will have more power output then older cr engine's. But from experience you need around twice the size for a 4 stroke when the majority of the time is at full throttle, like in our flat track racing. Basically the 450's wherent even fast enough to get around themselves, they where that slow compared to the 250's. Methanol and Ethanol creat more power then regular gasoline and is actually much safer then gas. Gas auto ignites around 495f mark, alcohol auto ignites around the 900f mark. Actually more around the 875f mark, but you need 20 to 30 percent more alcohol to have an engine properly run. Thats why vehicles that use alcohol get worse gas mileage then that of there gasoline brothern. The engine's that use alcohol make much higher HP numbers, now where talking a stock 250cr with MFI 50mm throttle body making 76hp on alcohol. Now thats with MFI and MFI makes a big difference with fuel automization in the cylinder, but just going from gas to alcohol in a 125 can net I believe up to 5hp. On a 1/4 mile track that may equate to a 1/2 to 1 full second off the other driver that is using alcohol.
But to get back on topic with racing, if they allowed a 4 stroke to race with our 2 stroke rc engine's the 4 stroke would need to be more then twice the size. You guys fail to remember that our 4 stroke engine's that are produced for our RC's are basically decades behind in design then there larger brethern. They have 2 valves, there not using dual rate spring's, there not using titanium valves, the valve bowls are not blended and there not polished the heads are not decked and kinda doubt that the head work is anything to be amazed at, and remember that in our engine's the timing isnt advanced when the rpm's get higher such as they would with other engine's that have Modules that control the timing of ignition. The 4 strokes that are desinged for our rc's are not up to par with that of our 2 strokes in total overal HP numbers. You can argue till your face turns blue(but I dont think that we are arguing just having a good conversation) but that doesnt make our Rc 4 stroke engine's any better in design then what they are currently. I would love to have a 4 stroke rc engine/s but in comparison they just dont supply the power needed, plus there a little small in size. .26 4 stroke equals that of somwheer inbetween a .12 to a .15 sized 2 stroke. More or less on the .12 side of things or that of a really cheap .15.
03-10-2008, 01:17 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
a rc 4-stroke can not run against a race 21 or 28, especially if they're modded. but they are cool, and would probably do well on a tight, slippery track against a race 21 or 28
and supposedly the 95 and 96 CR's where the most powerful 2-stroke honda made. the 95 125 was lacking low and mid, but once you got that thing screaming it could move, and the 96 250 isn't far behind in power of the 450's either. but the 450's dose beat it in torque.
since this is an RC forum I say stop talking bikes now (atleast I am)
and supposedly the 95 and 96 CR's where the most powerful 2-stroke honda made. the 95 125 was lacking low and mid, but once you got that thing screaming it could move, and the 96 250 isn't far behind in power of the 450's either. but the 450's dose beat it in torque.
since this is an RC forum I say stop talking bikes now (atleast I am)
03-10-2008, 06:53 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
like talking to a brick wall, they only make any sense when your drunk...
ORIGINAL: 125cchyperman
I realise that bikes have 38mm carbs. But we as racers tend to upgrade the carb's, upgraded carbs such as going to a 40mm big bore carb allows much more air volume to enter the engine at any point in time. Meaning the more air volume = more fuel= more power. And pre 95 cr engine's arent really worth anything, 96 and newer is where the port timing and ignition timing really started to perk up with honda's. A 95CR 125 doesnt have the power output of a 96CR 125, same goes for the 250's. But if you where to take a 96 450f and compare to that of a 96 cr250 the 450f would get killed everytime, no doubt. Your kinda comparing apples to oranges here when it comes to the bike year of manufacture.
And yeah a newer 450 will have more power output then older cr engine's. But from experience you need around twice the size for a 4 stroke when the majority of the time is at full throttle, like in our flat track racing. Basically the 450's wherent even fast enough to get around themselves, they where that slow compared to the 250's. Methanol and Ethanol creat more power then regular gasoline and is actually much safer then gas. Gas auto ignites around 495f mark, alcohol auto ignites around the 900f mark. Actually more around the 875f mark, but you need 20 to 30 percent more alcohol to have an engine properly run. Thats why vehicles that use alcohol get worse gas mileage then that of there gasoline brothern. The engine's that use alcohol make much higher HP numbers, now where talking a stock 250cr with MFI 50mm throttle body making 76hp on alcohol. Now thats with MFI and MFI makes a big difference with fuel automization in the cylinder, but just going from gas to alcohol in a 125 can net I believe up to 5hp. On a 1/4 mile track that may equate to a 1/2 to 1 full second off the other driver that is using alcohol.
But to get back on topic with racing, if they allowed a 4 stroke to race with our 2 stroke rc engine's the 4 stroke would need to be more then twice the size. You guys fail to remember that our 4 stroke engine's that are produced for our RC's are basically decades behind in design then there larger brethern. They have 2 valves, there not using dual rate spring's, there not using titanium valves, the valve bowls are not blended and there not polished the heads are not decked and kinda doubt that the head work is anything to be amazed at, and remember that in our engine's the timing isnt advanced when the rpm's get higher such as they would with other engine's that have Modules that control the timing of ignition. The 4 strokes that are desinged for our rc's are not up to par with that of our 2 strokes in total overal HP numbers. You can argue till your face turns blue(but I dont think that we are arguing just having a good conversation) but that doesnt make our Rc 4 stroke engine's any better in design then what they are currently. I would love to have a 4 stroke rc engine/s but in comparison they just dont supply the power needed, plus there a little small in size. .26 4 stroke equals that of somwheer inbetween a .12 to a .15 sized 2 stroke. More or less on the .12 side of things or that of a really cheap .15.
ORIGINAL: JB COMP
125cchyperman, bikes have a 38mm carb, and I've seen a 95 CR 125. 96 CR 250, and a 04 CRF450 run side by side and by the same rides (dad and bro) and the 450 would be the winner, unless in a tight track a 125 and 250 could be thrown around easier in there because of weight.
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
125cchyperman, bikes have a 38mm carb, and I've seen a 95 CR 125. 96 CR 250, and a 04 CRF450 run side by side and by the same rides (dad and bro) and the 450 would be the winner, unless in a tight track a 125 and 250 could be thrown around easier in there because of weight.
some one told me that methanol has less BTU's then gas. but then most of the races (like mini, drag, and F1) run methanol?
and yes, I heard the 450's gain alot from the stroker kits. since the 4-stroke have so much more torque then the 2-stroke why not gear the 4-stroke up?
And yeah a newer 450 will have more power output then older cr engine's. But from experience you need around twice the size for a 4 stroke when the majority of the time is at full throttle, like in our flat track racing. Basically the 450's wherent even fast enough to get around themselves, they where that slow compared to the 250's. Methanol and Ethanol creat more power then regular gasoline and is actually much safer then gas. Gas auto ignites around 495f mark, alcohol auto ignites around the 900f mark. Actually more around the 875f mark, but you need 20 to 30 percent more alcohol to have an engine properly run. Thats why vehicles that use alcohol get worse gas mileage then that of there gasoline brothern. The engine's that use alcohol make much higher HP numbers, now where talking a stock 250cr with MFI 50mm throttle body making 76hp on alcohol. Now thats with MFI and MFI makes a big difference with fuel automization in the cylinder, but just going from gas to alcohol in a 125 can net I believe up to 5hp. On a 1/4 mile track that may equate to a 1/2 to 1 full second off the other driver that is using alcohol.
But to get back on topic with racing, if they allowed a 4 stroke to race with our 2 stroke rc engine's the 4 stroke would need to be more then twice the size. You guys fail to remember that our 4 stroke engine's that are produced for our RC's are basically decades behind in design then there larger brethern. They have 2 valves, there not using dual rate spring's, there not using titanium valves, the valve bowls are not blended and there not polished the heads are not decked and kinda doubt that the head work is anything to be amazed at, and remember that in our engine's the timing isnt advanced when the rpm's get higher such as they would with other engine's that have Modules that control the timing of ignition. The 4 strokes that are desinged for our rc's are not up to par with that of our 2 strokes in total overal HP numbers. You can argue till your face turns blue(but I dont think that we are arguing just having a good conversation) but that doesnt make our Rc 4 stroke engine's any better in design then what they are currently. I would love to have a 4 stroke rc engine/s but in comparison they just dont supply the power needed, plus there a little small in size. .26 4 stroke equals that of somwheer inbetween a .12 to a .15 sized 2 stroke. More or less on the .12 side of things or that of a really cheap .15.
03-10-2008, 07:52 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
like talking to a brick wall, they only make any sense when your drunk...
like talking to a brick wall, they only make any sense when your drunk...
But if you could kindly tell me how it's like talking to a brick wall I would love to know though. Cause I stated things from my experience that I have gone through so far.
03-10-2008, 08:32 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
4-strokes are made for the rc planes, which it doesn't take alot of rpms to turn a prop, but a 70FS would be turn the same prop of what a 50 or 60 2-stroke would (I think)
03-10-2008, 08:57 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
we're talking about rc car racing, which is won on acceleration out of corners, not speed on the straits, yet i keep reading about a CR125 engine running on methanol in a flat oval track midget car..
03-10-2008, 09:01 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
You want a 4 stroke in an rc...build it. If it trips your trigger then do it and don't pay no mind to anything else. CURRENTLY a 21-28 2 stroke will spank anything under a .70 4 stroke and probably bigger. Apples and oranges to compare the 4 stroke plane to a hot 2 stroke car engine. Airplane engines must have power at low rpm and car engines need to be able to rev high for mph. Car engines are designed for performance and plane engines are designed for longevity. HUGE difference. The comparison between full scale and rc is ridiculous. And finally gasoline has more btu/unit than alcohol. Ethanol belongs in a shot glass, not an internal combustion engine. 2 wrongs don't make a right but 3 lefts do.
03-10-2008, 09:03 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
we're talking about rc car racing, which is won on acceleration out of corners, not peak HP on the straits, yet i keep reading about a CR125 engine running on methanol in a flat oval track midget car..
we're talking about rc car racing, which is won on acceleration out of corners, not peak HP on the straits, yet i keep reading about a CR125 engine running on methanol in a flat oval track midget car..
and a OS 52 surpass, Saito 52, Saito 40 something will be about the same as a rtr 15 or 18. Saito are more powerful per CC then the OS, I think a Saito 65 has the same power output a OS 70 surpass has.
there used to be video of a Hyper ST with a OS 120 in it on youtube, but they took it down, it was as fast as a rtr 28, had lots of low end. but I heard the 120's are dogs, that it would have been better to drop a OS 91 in there instead.
03-11-2008, 12:56 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
we're talking about rc car racing, which is won on acceleration out of corners, not speed on the straits, yet i keep reading about a CR125 engine running on methanol in a flat oval track midget car..
we're talking about rc car racing, which is won on acceleration out of corners, not speed on the straits, yet i keep reading about a CR125 engine running on methanol in a flat oval track midget car..
But anyways to GET BACK ON TOPIC, I realise that our rc tracks are more like that of motorcross tracks with bumps and jumps and where acceleration is key. But you still havent addressed the fact that the 4 strokes designed for our rc's our behind in design then that of there larger brethern. By your calculations the .26 4 stroke made by O.S specifically designed for our rc's should have the power of a engine approx the size of a .21. But well use a good .18 like the .18TZ, that particular 4 stroke will not create more power then that of the TZ. Thats what I'm getting at here. Now if a lot of company's started to make 4 strokes designed for our RC's then yeah the 4 strokes would be much much better in the years to come. But right now there lagging behind and just about everybody has 2 strokes on there cars with the exceptions of a few. So nobody's really worried about improving the design of the 4 stroke for our cars and trucks. I believe this is about the 2nd or 3rd time I said something along these lines now, but youve still yet to address those facts that I have stated.
I realise that where talking about rc's on a track similar to that of a motorcorss track.
03-11-2008, 01:09 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
that's my point, if enough time was put into development of a good 4 stroke (i said this in my first post lol) i think we could get 4 strokes only 50% larger then there two stroke rivals to be similar in power, while having a much broader torque curve at the same time, it's easy to tell by looking at the O.S .26 that not much has changed from the plane engines, what i have in mind would essentially be a complete re-design of the current 4 strokes, from gear driven low mounted cam shaft to an overhead camshaft design to reduce recuperating mass, 4 valves per cylinder to improve flow rates into the cylinder/s, going from a square (equal bore and stroke) to and under square (larger bore then stroke) to both lower the center of gravity, and lower the piston speed for a particular RPM for a more freely revving engine, and a self contained lubricating system to remove all oil form the fuel, which would mean alone at a guess 10-20% more power if nothing else was change on the engine (even if it does weigh little more).
of course i see that theres not really demand for such a 4 stroke yet, and originally the main drive for 4 stroke motocross bike was emission regulations, and then in the race for lower emissions also became more advanced and power (it's been ten years since the Yamaha YZF 400, the first mainstream performance 4 stroke), the way things are going now though, i could see RC's eventually going the same direction.
of course i see that theres not really demand for such a 4 stroke yet, and originally the main drive for 4 stroke motocross bike was emission regulations, and then in the race for lower emissions also became more advanced and power (it's been ten years since the Yamaha YZF 400, the first mainstream performance 4 stroke), the way things are going now though, i could see RC's eventually going the same direction.
03-11-2008, 01:41 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
that's my point, if enough time was put into development of a good 4 stroke (i said this in my first post lol) i think we could get 4 strokes only 50% larger then there two stroke rivals to be similar in power, while having a much broader torque curve at the same time, it's easy to tell by looking at the O.S .26 that not much has changed from the plane engines, what i have in mind would essentially be a complete re-design of the current 4 strokes, from gear driven low mounted cam shaft to an overhead camshaft design to reduce recuperating mass, 4 valves per cylinder to improve flow rates into the cylinder/s, going from a square (equal bore and stroke) to and under square (larger bore then stroke) to both lower the center of gravity, and lower the piston speed for a particular RPM for a more freely revving engine, and a self contained lubricating system to remove all oil form the fuel, which would mean alone at a guess 10-20% more power if nothing else was change on the engine (even if it does weigh little more).
of course i see that theres not really demand for such a 4 stroke yet, and originally the main drive for 4 stroke motocross bike was emission regulations, and then in the race for lower emissions also became more advanced and power (it's been ten years since the Yamaha YZF 400, the first mainstream performance 4 stroke), the way things are going now though, i could see RC's eventually going the same direction.
that's my point, if enough time was put into development of a good 4 stroke (i said this in my first post lol) i think we could get 4 strokes only 50% larger then there two stroke rivals to be similar in power, while having a much broader torque curve at the same time, it's easy to tell by looking at the O.S .26 that not much has changed from the plane engines, what i have in mind would essentially be a complete re-design of the current 4 strokes, from gear driven low mounted cam shaft to an overhead camshaft design to reduce recuperating mass, 4 valves per cylinder to improve flow rates into the cylinder/s, going from a square (equal bore and stroke) to and under square (larger bore then stroke) to both lower the center of gravity, and lower the piston speed for a particular RPM for a more freely revving engine, and a self contained lubricating system to remove all oil form the fuel, which would mean alone at a guess 10-20% more power if nothing else was change on the engine (even if it does weigh little more).
of course i see that theres not really demand for such a 4 stroke yet, and originally the main drive for 4 stroke motocross bike was emission regulations, and then in the race for lower emissions also became more advanced and power (it's been ten years since the Yamaha YZF 400, the first mainstream performance 4 stroke), the way things are going now though, i could see RC's eventually going the same direction.
Yeah thats what I was trying to get at, Now I think me and you are on the same page. If they did put time into building and redesigning them then yeah you could get them to less then half the size of that of a 2 stroke. But the current design doesnt allow that though. I would love to see a good high performance 4 stroke designed specifically for a 4 stroke. Now I wouldnt go as far as to saying that a net gain of 10-20% net gain in power from taking the oil out of the fuel but I'm sure some gain would be seen. But one thing though I really hate to go back into the midget thing but with the 600's that we use, because of the high rpm's we also use top end lube in the fuel. Basically 2 stroke oil in the fuel to help lube the top end. Not saying that we would need to do that with these 4 strokes as those engine's on a straight go from 12,000 to 16,000 rpms and sustain those rpm's through out the whole race until a yellow is brought out (Yeah many of those engine's blow rods quite frequently). But we might have to do that in these 4 strokes if they where to rev higher, but then again maybe I'm just thiking to cautiously.
But yeah 4 strokes where brought in because of the 2 stroke's with the emissions. But I'm with you on this one ttoks, if they completely did a new design and actually put some time and effort into a 4 stroke I think it would be wicked. I personally would have to get one. But I dont see a high performance 4 stroke coming out anytime soon [
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03-11-2008, 08:57 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
lets leave it at this, 4-strokes have their place.
and it would be hard to fine a stiff enough spring to keep the valve from floating at 26,000-30,000rpm
and it would be hard to fine a stiff enough spring to keep the valve from floating at 26,000-30,000rpm
03-11-2008, 04:28 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
Ducati got around ultra stiff springs, and problems associated with them, and valve float at any rpm with their (sp?)desmodromic valve train... oversquare design to lower cg and turn around and put ohc and 4 valves per cylinder???
y'all keep it up, it's interesting
y'all keep it up, it's interesting
03-12-2008, 12:00 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
I dont think valve's floating would really be an issue here, as said it's more about cam profile and can be easily gotten over using a heavier or a little larger spring. I think the problem would be getting a good enough cam profile to provide both good bottom end and good top end power. Since there is such a larger vareance in rpm's, now again maybe I'm over complicating thing's here. Maybe a cam profile more for the mid range would suit everybody.
But with a large enough bore and a smaller stroke, I dont think the CG would be all that noticable as much would think, beside's valve's and valve spring dont weigh all that much. Now the cams might be a different story, but if made out of the correct material could also be pretty light and plenty strong enough. But I could see there being a problem of keeping the top end lubed well enough though.
But with a large enough bore and a smaller stroke, I dont think the CG would be all that noticable as much would think, beside's valve's and valve spring dont weigh all that much. Now the cams might be a different story, but if made out of the correct material could also be pretty light and plenty strong enough. But I could see there being a problem of keeping the top end lubed well enough though.
03-12-2008, 12:17 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
While on the topic of 4 strokes..without starting a flame war or anything or opening up a can of worms..Do you guys believe that forced induction would work better say with that os FS-26? Or are we still looking at minimal to no gains? I'm not basing this off efficiency or whats more economical, just purely theoretical.
03-12-2008, 12:55 PM
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RE: 4stroke on 1/10 or 1/8th truck or car
It would work, from what I know they all ready make forced induction 4 stroke engine's for rc's but I believe there in planes. Now would the R&B innovations supercharger work prolly not, thats a very cheapely made(in my opinion) forced induction supercharger, if a good superchager was made then yes since the exhaust valves would close before the intake valves would. Infact if you design the engine to be used with the supercgarger it would work awesome. a little valve overlap, meaning the exhaust valve would be open for a little while the intake valve is open would make this work pretty good in my eye's.
I had thought about that while we where talking about making 4 stroke engine's better, infact if we could make a good 4 stroke with a forced induction that was extremely efficent and did a lot work on it. I believe in a couple of years the rc speed record would be given to a 4 stroke and to an electric. But we first must learn to walk before we run.
I had thought about that while we where talking about making 4 stroke engine's better, infact if we could make a good 4 stroke with a forced induction that was extremely efficent and did a lot work on it. I believe in a couple of years the rc speed record would be given to a 4 stroke and to an electric. But we first must learn to walk before we run.
03-13-2008, 12:58 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
O.S offer (or at least used to offer) supercharged versions of ther .91 and 1.2 CI 4 stroke plane engine, they claimed a 30% power increase.
03-13-2008, 01:46 AM
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RE: 4stroke on 1/10 or 1/8th truck or car
ORIGINAL: ttoks
O.S offer (or at least used to offer) supercharged versions of ther .91 and 1.2 CI 4 stroke plane engine, they claimed a 30% power increase.
O.S offer (or at least used to offer) supercharged versions of ther .91 and 1.2 CI 4 stroke plane engine, they claimed a 30% power increase.
