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Maximising engine characteristics.

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Maximising engine characteristics.

Old 09-27-2018, 02:16 PM
  #151  
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Originally Posted by Roelof
I think it gave too much cooling keepng the sleeve too small giving fast worn pistons. They should have used a piston material with a less expansion rate to work with the lower expansion of the sleeve. But now they went back to normal button heads and cooling heads
It was a problem with inconsistent tuning as well, that was a problem that could be fixed though.
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Old 09-28-2018, 03:10 AM
  #152  
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Originally Posted by NitroVein
What gave you the idea that it burns at 6,35m/s? The engine would be a complete dud with that burn rate.


You might confuse some things...
First of, do you want to make the most power or the most fuel efficient engine? They don't go hand in hand, just look at the tests they have done between sports cars and ECO friendly cars. The ECO friendly car runs as fast as it can around a track and the sport car follows behind, the sport car always use less fuel.
Second, why would the engine lose bottom end, and throttle respons from a quicker burn rate?
Third, if you'e running in to preignition you don't want to increase the head clearance (in itself).
6.35m/s is the average at that rpm I calculated but yes it's a mistake, should be half a cycle so burn rate 12.7m/s. Provided it burns until the exhaust port started to open,which I don't know if that happens . At this point I don't have any data that points where it stops burning but we know the average of fuel spent each cycle, from there we calculate how much fuel it has and how much air it needs I think.

I don't have an objective set in stone, if I can tune the engine to be effective at the tracks I race the better. I want an advantage by knowing what are the conditions the engine works at its best. This is the intention of this thread, to find out what is going on and have more understanding about it.

For a start I know that the engine performs the best when it's in tune with the pipe so knowing more about them and making the best of both in varying conditions would be a good thing.

Edit, the eco car was pushing the air in front of the sports car, lessening drag for the follower and it was driving out of the eco range. The opposite would be true, the sports car can't be as good as the eco car during normal driving.
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Last edited by 30Tooth; 09-28-2018 at 07:25 AM.
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Old 09-28-2018, 08:54 AM
  #153  
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Originally Posted by 30Tooth
6.35m/s is the average at that rpm I calculated. Provided it burns until the exhaust port started to open,which I don't know if that happens . At this point I don't have any data that points where it stops burning but we know the average of fuel spent each cycle, from there we calculate how much fuel it has and how much air it needs I think.

I don't have an objective set in stone, if I can tune the engine to be effective at the tracks I race the better. I want an advantage by knowing what are the conditions the engine works at its best. This is the intention of this thread, to find out what is going on and have more understanding about it.

For a start I know that the engine performs the best when it's in tune with the pipe so knowing more about them and making the best of both in varying conditions would be a good thing.
I see, well the mixture burns a lot faster, most of it at least. That's what the turbulens from the squish helps with, and also what you have to trade with, as any fuel mixture trapped in the squish area wont burn or burn to late to be able and apply any force, and without out squish it burns to slow. Take your pick.

Finding a optimum engine for your track is a good idea, as it's pretty much a matter of how efficiently you can apply the energy from the fuel to the track surface. If you don't have enough power the engine will struggle, and if you have too much it will waste it. So everything from the tires, chassi setup, drive line efficiency, clutch, servo setup etc will be something to have in mind. Maybe not the answer you're looking for, but it's worth mentioning as you can focus too much on the small pieces and forget how it all needs to come together.

Then the whole engine is full of trade offs, it doesn't matter if you make one part 100% theoretically efficient if you loose more at another place in reality. As long as you're not trying to make the most power for instance, then you have a lot of different ways to skin the cat in order to reach your goal.
For sake of argument it's never wrong to discuss each part individually and everyone has to start somewhere, but when you see even so called experienced engine modders thinking it's something special to look at at-least all the basic parameters as a whole picture... be better then that or get a good software to help you!

Sorry for the rant, but I really am trying to give you some good advice.
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Old 09-28-2018, 09:02 AM
  #154  
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Originally Posted by 30Tooth

Edit, the eco car was pushing the air in front of the sports car, lessening drag for the follower and it was driving out of the eco range. The opposite would be true, the sports car can't be as good as the eco car during normal driving.
It didn't have anything to do with how close they were, but you're right that during some normal city driving the small ECO car would be more fuel efficient, they can't be best for everything, there is always trade offs so take your pick.
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Old 09-28-2018, 12:20 PM
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Originally Posted by NitroVein
I see, well the mixture burns a lot faster, most of it at least. That's what the turbulens from the squish helps with, and also what you have to trade with, as any fuel mixture trapped in the squish area wont burn or burn to late to be able and apply any force, and without out squish it burns to slow. Take your pick.

Finding a optimum engine for your track is a good idea, as it's pretty much a matter of how efficiently you can apply the energy from the fuel to the track surface. If you don't have enough power the engine will struggle, and if you have too much it will waste it. So everything from the tires, chassi setup, drive line efficiency, clutch, servo setup etc will be something to have in mind. Maybe not the answer you're looking for, but it's worth mentioning as you can focus too much on the small pieces and forget how it all needs to come together.

Then the whole engine is full of trade offs, it doesn't matter if you make one part 100% theoretically efficient if you loose more at another place in reality. As long as you're not trying to make the most power for instance, then you have a lot of different ways to skin the cat in order to reach your goal.
For sake of argument it's never wrong to discuss each part individually and everyone has to start somewhere, but when you see even so called experienced engine modders thinking it's something special to look at at-least all the basic parameters as a whole picture... be better then that or get a good software to help you!

Sorry for the rant, but I really am trying to give you some good advice.
No need to apologize, I am thankful for your advice and have been learning a lot. Please don't take me wrongly.

The little I knew about squish was that the mixture was sent in towards the combustion chamber but now realize it's like a piston shield where the mixture is kept away from the burn front. From this one can assume that you should make the squish band as little as possible maybe even not having any.
About the other stuff, I know that the car is a system and everything has to work right together but yeah I have to start somewhere and it was the difficult stuff first

​​​​​​About software I have been gathering some, I do want to make sure I can understand more about port timings and tuned pipe relation. I have been looking at the free ones for tuned pipes, any that you can recommend?

Again thanks for the heads up you and the others!
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Old 09-28-2018, 05:06 PM
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Originally Posted by 30Tooth
No need to apologize, I am thankful for your advice and have been learning a lot. Please don't take me wrongly.

The little I knew about squish was that the mixture was sent in towards the combustion chamber but now realize it's like a piston shield where the mixture is kept away from the burn front. From this one can assume that you should make the squish band as little as possible maybe even not having any.
About the other stuff, I know that the car is a system and everything has to work right together but yeah I have to start somewhere and it was the difficult stuff first

​​​​​​About software I have been gathering some, I do want to make sure I can understand more about port timings and tuned pipe relation. I have been looking at the free ones for tuned pipes, any that you can recommend?

Again thanks for the heads up you and the others!
The clearance is usually best to have a small as you dare if you're after using all the fuel in the combustion chamber, but you also need to work with other factors, so it might not be possible or any advantage. If you would build an engine that run a constant rpm things would be easy, but with our cars we are at the opposite end of the spectrum pretty much. And if you mean area, then no you absolutely need it for these engines, you need to control the heat and get enough turbulence or the engine will be a dud.
I know that you're familiar with taking several things in to consideration, I've read how you analyze chassis, give it some time and you will probably have a leg up many here.
As far as software, it's kind of difficult... Some uses the old way of thinking, that isn't incorrect, just incomplete. Then you have some new like the one you posted earlier that takes other things in to consideration, but sort of leave all the old good parts behind for some strange reason and also draws some really strange conclusions. And in the end I've not seen any that takes every part in to consideration, old-new-missed parts.
But lets face it, first of it's a tool most of the time so you need to know what you're doing anyhow, and second of you can copy just timing numbers from another engine and have success. Trial and error still works and if you don't intend to make pipes yourself you need to work with what you got!
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Old 09-29-2018, 03:29 AM
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At this point I think I will have to build a pipe myself, but first try to learn as much as possible. I've been searching airplane engines and the ones I've seen don't have squish bands...
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Old 09-29-2018, 03:52 AM
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If you want to get more out of it you should try a boat pipe. These are on full length for the engine and do provide some more poer. They are populair upgrades in monstertrucks and tracktor pulling.
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Old 09-29-2018, 04:46 AM
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Originally Posted by 30Tooth
At this point I think I will have to build a pipe myself, but first try to learn as much as possible. I've been searching airplane engines and the ones I've seen don't have squish bands...
There is an old question that goes: should you pipe to port, or port to pipe. A good pipe will usually work pretty good on many engines funny enough.
I don't think I've seen any engines without squish band though. You need to figure out what you intend to do with the engine, if it's still for a 1/8 buggy racing in current regulations, or not. If it's just maximizing engine efficiency in a two stroke there are a lot of ideas out there, but if you intend to use if for current application you wont get an effective package that way.
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Old 09-29-2018, 06:12 AM
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Originally Posted by NitroVein
There is an old question that goes: should you pipe to port, or port to pipe. A good pipe will usually work pretty good on many engines funny enough.
I don't think I've seen any engines without squish band though. You need to figure out what you intend to do with the engine, if it's still for a 1/8 buggy racing in current regulations, or not. If it's just maximizing engine efficiency in a two stroke there are a lot of ideas out there, but if you intend to use if for current application you wont get an effective package that way.
Indeed, the 2058 pops to mind as it has worked well on sirios and nr I have,even SH engines.

Very well put, at this point we need to know what compromises have to be made and still follow rules. If the pipe is good enough maybe even go racing with it just to see how it stacks up. Then baby steps to improve the package.

I think the OS 12 and 28 have less squish bands than 21 engines, at least from the pics. Still trying to spot a pattern.
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Old 09-29-2018, 07:38 AM
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Originally Posted by 30Tooth
Indeed, the 2058 pops to mind as it has worked well on sirios and nr I have,even SH engines.

Very well put, at this point we need to know what compromises have to be made and still follow rules. If the pipe is good enough maybe even go racing with it just to see how it stacks up. Then baby steps to improve the package.

I think the OS 12 and 28 have less squish bands than 21 engines, at least from the pics. Still trying to spot a pattern.
You've got the old 9886, 9853. Onroad seem to often use the 2015, and both on & offroad uses the 2069, and that's just on top of my head.
Even Novarossi has gone for outside source for a pipe that worked well for other brands, that should tell you something.
New 1/8th off-road tuned pipe - NOVAROSSI WORLD

Different engines do use different size squish area, but it's usually difficult to see exactly how much there is in difference.
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Old 09-29-2018, 07:53 AM
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The funny thing with most pipes is that the older ones are still faforite. The 2015 is with most Novarossi drivers most used.
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Old 09-29-2018, 08:37 AM
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Originally Posted by Roelof
The funny thing with most pipes is that the older ones are still faforite. The 2015 is with most Novarossi drivers most used.
Yes, if the wheel was round to begin with there is no reason trying to invent a rounder one. I like that pipe for offroad as well.
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Old 10-01-2018, 02:54 AM
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Originally Posted by NitroVein
You've got the old 9886, 9853. Onroad seem to often use the 2015, and both on & offroad uses the 2069, and that's just on top of my head.
Even Novarossi has gone for outside source for a pipe that worked well for other brands, that should tell you something.
New 1/8th off-road tuned pipe - NOVAROSSI WORLD

Different engines do use different size squish area, but it's usually difficult to see exactly how much there is in difference.
The 98xx pipes seem to always work well, they must be very well designed. Still on the hunt for them.
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Old 10-01-2018, 04:25 AM
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Originally Posted by 30Tooth
The 98xx pipes seem to always work well, they must be very well designed. Still on the hunt for them.
I believe you can buy them pretty much anywhere, at least online. But as usual, if they produce more power they will likely use more fuel as well, power doesn't come from nothing.
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