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XP Turbo Kits---soon!!!
- Thread starter DWHalverson
- Start date
It's not even a contest triple7.....With a Purelogic or Similar fuel system controls your able to run consistant mapped performance everyday with the aid of the programmer. A tool you don't have on carberated sleds and what seperates EFI vs Carberation sleds especially at elevation where the "Air" effects "Air/Fuel Ratio" as well as "boost/compression".
OT
Boost at 5-8 psi probably wont stress a motor at all. Dave does'nt need defending he is going to make a product I will probably buy. I was just making a point as to keeping sleds reliable. I am in no means saying turbo's are bad quite the contrary, I can hardly wait. Will I turn it up?? Probably. Will I keep it turned up? Who knows. All I am saying is if a guy wants a reliable fun sled then he should keep it within reason or there might or might not be problems.
So now for a question. Dave when boosting a 2 stroke how does compression ratio differ from say a car engine. For example my ZZ4 motor in my stingray corvette cant be turbo'ed because the compression ratio is to high (I think 12 to 1) Why can we boost the 12 to 1 sled motor?
Carbs will always be an issue vs the ease of efi when it comes to boosted applications. Not impossable obviously but an issue.
Here is what I know, think I know or how I look at it.
With efi the fuel is being injected at a higher pressure so it isn't too big of a deal on the boosted sleds. You just have to change your fuel curve to match the boost requirements. That is easy with the nice new efi control boxes available now. The fuel curve can be controlled in the carb setup too with the correct equipment to deliver the fuel and then the specific carb calibration. The electrical power output on the newer sleds are way more than the sleds from 10 years ago. So this gives us more consistant voltage for our turbo electrical devices. Yes the new sleds use more power than they did 10 years ago, but they seem to have more left over. Even the electric fuel pumps use less power than they used to. The biggest thing is the proper carb calibration. It's no different than even the stock carbed sled. Toss in the wrong jetting and you will fight it nonstop. Throttle chop and bogging out were more of an issue with the self contained turbos not being set up properly. The guys that knew how to do it didn't seem to have issues with this. Back then and today, I don't think a lot of the self contained turbos run BOVs until the boost gets up there. I feel you have to have some way to bleed the boost off when the throttle is dumped-ie BOV. The BOV does have to be set to the correct parameters just like the other components and they all need to work TOGETHER. If they don't, you know how it will run. I feel in my testing, the carbed turbo sleds vs the efi turbo sleds, the two are very consistant with each other. Now when they get the closed loop efi controllers done then you should/will not have to even touch your turboed efi sled for the proper fuel curve. From my expierence there are minor adjustments for both. Needed, maybe not, but that's just how I am.
Dave
Here is what I know, think I know or how I look at it.
With efi the fuel is being injected at a higher pressure so it isn't too big of a deal on the boosted sleds. You just have to change your fuel curve to match the boost requirements. That is easy with the nice new efi control boxes available now. The fuel curve can be controlled in the carb setup too with the correct equipment to deliver the fuel and then the specific carb calibration. The electrical power output on the newer sleds are way more than the sleds from 10 years ago. So this gives us more consistant voltage for our turbo electrical devices. Yes the new sleds use more power than they did 10 years ago, but they seem to have more left over. Even the electric fuel pumps use less power than they used to. The biggest thing is the proper carb calibration. It's no different than even the stock carbed sled. Toss in the wrong jetting and you will fight it nonstop. Throttle chop and bogging out were more of an issue with the self contained turbos not being set up properly. The guys that knew how to do it didn't seem to have issues with this. Back then and today, I don't think a lot of the self contained turbos run BOVs until the boost gets up there. I feel you have to have some way to bleed the boost off when the throttle is dumped-ie BOV. The BOV does have to be set to the correct parameters just like the other components and they all need to work TOGETHER. If they don't, you know how it will run. I feel in my testing, the carbed turbo sleds vs the efi turbo sleds, the two are very consistant with each other. Now when they get the closed loop efi controllers done then you should/will not have to even touch your turboed efi sled for the proper fuel curve. From my expierence there are minor adjustments for both. Needed, maybe not, but that's just how I am.
Dave
The compression does put limits on the engine when boosting. As far as your car goes, I'm sure if you kept the boost low and tossed in enough high octane rocket fuel it could be boosted. Would it run as good as the same engine with less compression and even a tad more boost--I doubt it.
In the boosted applications turbo/supercharger, you let that device make the power. I know of guys with super low compression ratios and then big boost numbers. They want to make huge power and that is how they need to do it. Pull compression out, hopefully not at the cost of throttle response and torque and turn it way up
. Every component has a mechanical limit. We just don't want to be scattering parts just so we can say we run 20 psi of boost, do we? I want to ride and that is where the kits will be "suggested" to run at. We will be destroying parts along the way trying different things and finding the limits. It all takes money.
Dave
In the boosted applications turbo/supercharger, you let that device make the power. I know of guys with super low compression ratios and then big boost numbers. They want to make huge power and that is how they need to do it. Pull compression out, hopefully not at the cost of throttle response and torque and turn it way up
. Every component has a mechanical limit. We just don't want to be scattering parts just so we can say we run 20 psi of boost, do we? I want to ride and that is where the kits will be "suggested" to run at. We will be destroying parts along the way trying different things and finding the limits. It all takes money.Dave
Dave, someone needes to develope a carberator specific for turbo 2 stroke applications..... High Performance Carbs are common in the "need for speed community"......Kalahammer/PSI brought to market approx. 10 years ago a Big Air Carberator that was completely adjustable (jetting,pilot,needle) externally from the carberator body. You would still have to open the hood to adjust while having the access to adjust externally would be a bonus. I think a modshop for the motorcross industry still builds a similar verison.
I wonder how having carberators larger than 40mm would work ???
OT
I wonder how having carberators larger than 40mm would work ???
OT
I have seen Bruce's magic carbs and they indeed had some easy adjustability to them. Generally when the carb diameter gets bigger the tuneing has to be more spot on and they tend to be less forgiving. This is on NA engines. In the turbo world not sure if the side affects would be as great, but I doubt the benefits would be that great either. I know they make bigger throttle bodies for the Cats on boost, but I think the main thing is for the auxillary injectors and cleans up the bottom end and the tune becomes more consistant getting the auxillary injectors out of the charge box. I think a lot of people have forgotten the adjustability of carbs. We are looking at doing a mod to allow for an air adjustment on the idle circuit along with the factory fuel screw adjustment. More details later on that though.
Dave
Dave
I think thats a pretty good plan. I think that could seriously help bottom end tuning.
I think it's a good plan too. Problem is has anyone even seen the fuel screw adjustments on thier XP with the carbs on? Looking at building some sort of remote adjustment for these. Gotta love the 20 pounds of crap in a 5 pound bag build platform used now days.
? Looking at building some sort of remote adjustment for these. Gotta love the 20 pounds of crap in a 5 pound bag build platform used now days.LOL ya what a b@tch to get to. They suck for sure. I adjusted mine on the hill one day and ended up having to take the carbs off the reed boots to get to the back one.
They build flex jet fuel screws for motocross bikes used to make the fuel screw adjustable from an easier location. I have one on both my race bikes and they work well. You may check them out for a sled application, I was thinking about trying to make something like that work.
You can check them out from this address:
http://www.mxsouth.com/r&dracing/rd...e-original-rds-flex-jet-remote-fuel-screw.htm
They build flex jet fuel screws for motocross bikes used to make the fuel screw adjustable from an easier location. I have one on both my race bikes and they work well. You may check them out for a sled application, I was thinking about trying to make something like that work.
You can check them out from this address:
http://www.mxsouth.com/r&dracing/rd...e-original-rds-flex-jet-remote-fuel-screw.htm
Mikuni and Khein have dominated the market place. Imo there always room for a better mouse trap especially with the available technology.....When you look at a Mikuni Carb. the technology and function have not changed with the times.
Build it, make it work, and they will come.
OT
Build it, make it work, and they will come.
OT
Maybe but dude, mikuni an Kehein have tons of development time into making their carburators homogenize the fuel with the air well. They are tunable, may take a bit of time but they work well. IMO the expense of an aftermarket carb being developed does not make sense, spend the time and work out a curve that works with boosted applications. The curve on the factory NA sled isnt bad in my opinion. Just recalibrate for boost, use the powerjets to adjust mid to top fuel for boost changes and it should work well. I think the base setup is crucial. get it right, make the fuel screws possible to adjust, possibly add an air screw and we will make these kits work well.
I have a gut feeling that for all out horsepower the carb turbos will out do the fuel injection turbos. Just my opinion tho.
The fact still remains that you have to take the carberator apart to jet and adust clip/needles. The technolgy is there to illiminate taking the carberator apart making adjust/tuning simpler.
OT
OT
S
Sako7STW
Well-known member
I have a few observational questions if you guys dont mind.
A 2-stroke works via a combination of air and fuel obviously. But they also need the pulse timing of the exaust and its expansion chamber. How do you get around this with a turbo? Wouldnt you bennifit from an exaust designed for the higher volumes of exaust? I mean more air/fuel in, the more that has to come out and the stock exaust is desighed specifically for a certain amount of flow and RPM. Just curious how turbos effect this?
I have built a few Banshee's now and they have a "lightswitch" like powerband that reminds me of a turbo. When they "get on the pipe" the machine comes to life just like a motor does when the turbo spools. If you can tune a carb for this type of powerband I would think the fuel curve would be simular to that of a turbo. On my Banshee's I have used a 34-35mm carb instead of the stock 26mm carbs. I did this to try and get as much air in to the motor as possible at my higher elevation. I run massive carb mount K&N filters to supply the air. To get them to run properly I had to increase my compression, run very aggressive porting, and on my stroker motor I ran AV Gas with the additional aid of a dial-a-jet. On my stock stroke I was able to run premium and no dial-a-jet but the powerband was not as wide or as smooth. Adding the dial-a-jet gave me what i think of as a forth dimension of tuning as it added another fuel circut I could tune with along with the pilot, needle tapering, and main jet. I wonder if adding a dial-a-jet would help in the tuning of a turbo sled in that it would supply the additional fuel needed while on boost but has no effect on the low rpm/off boost fuel needs??
Anyone tried looking into Lectron carbs for running on boost? Didnt have much luck with them on a NA sled as they seamed to fight the pulse but if my suspicions about boost is right and that pulse becomes less of a factor, the adjustability of the lectrons might work very well.
Just thinking out loud. Watching this thread and will be watching the results of the kit closely as I would love to do this to my new sled but not till it is proven. I dont have the time nor the $$ to be someone elses ghiney pig.
A 2-stroke works via a combination of air and fuel obviously. But they also need the pulse timing of the exaust and its expansion chamber. How do you get around this with a turbo? Wouldnt you bennifit from an exaust designed for the higher volumes of exaust? I mean more air/fuel in, the more that has to come out and the stock exaust is desighed specifically for a certain amount of flow and RPM. Just curious how turbos effect this?
I have built a few Banshee's now and they have a "lightswitch" like powerband that reminds me of a turbo. When they "get on the pipe" the machine comes to life just like a motor does when the turbo spools. If you can tune a carb for this type of powerband I would think the fuel curve would be simular to that of a turbo. On my Banshee's I have used a 34-35mm carb instead of the stock 26mm carbs. I did this to try and get as much air in to the motor as possible at my higher elevation. I run massive carb mount K&N filters to supply the air. To get them to run properly I had to increase my compression, run very aggressive porting, and on my stroker motor I ran AV Gas with the additional aid of a dial-a-jet. On my stock stroke I was able to run premium and no dial-a-jet but the powerband was not as wide or as smooth. Adding the dial-a-jet gave me what i think of as a forth dimension of tuning as it added another fuel circut I could tune with along with the pilot, needle tapering, and main jet. I wonder if adding a dial-a-jet would help in the tuning of a turbo sled in that it would supply the additional fuel needed while on boost but has no effect on the low rpm/off boost fuel needs??
Anyone tried looking into Lectron carbs for running on boost? Didnt have much luck with them on a NA sled as they seamed to fight the pulse but if my suspicions about boost is right and that pulse becomes less of a factor, the adjustability of the lectrons might work very well.
Just thinking out loud. Watching this thread and will be watching the results of the kit closely as I would love to do this to my new sled but not till it is proven. I dont have the time nor the $$ to be someone elses ghiney pig.
S
Sako7STW
Well-known member
Here is a nice descripition of expansion chambers and pulse for a 2-stroke for those that dont already know this sort of thing (I find it interesting it compares them to a turbo);
http://auto.howstuffworks.com/question636.htm
One on expansion chambers that shows what the exaust does better:
http://auto.howstuffworks.com/frame...nakajak.com/skalmanmc/rd350/tuning/expan1.htm
http://auto.howstuffworks.com/question636.htm
One on expansion chambers that shows what the exaust does better:
http://auto.howstuffworks.com/frame...nakajak.com/skalmanmc/rd350/tuning/expan1.htm
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Basically the expansion chamber or pipe on a two stroke works to self supercharge the motor.
A turbo obviously supercharges the motor on its own. However gus bohne posted in another thread that he gained like 130 horse on a boosted mercury by switching to an xcr pipe setup from factory manifolds. My feeling is that the pressure waves dont leave when the motor is on boost. I think they exist and are probably very very important in getting a boosted two stroke to make full power. In theory, the waves would have a greater magnitude because you are in effect making the motor think its bigger. I dont know much about this, I am sure there are others that have way more developed thoughts on this and probably evidence to prove their point.
My feeling is that a pipe specifically made to work for boost could yield gains. Thoughts??
A turbo obviously supercharges the motor on its own. However gus bohne posted in another thread that he gained like 130 horse on a boosted mercury by switching to an xcr pipe setup from factory manifolds. My feeling is that the pressure waves dont leave when the motor is on boost. I think they exist and are probably very very important in getting a boosted two stroke to make full power. In theory, the waves would have a greater magnitude because you are in effect making the motor think its bigger. I dont know much about this, I am sure there are others that have way more developed thoughts on this and probably evidence to prove their point.
My feeling is that a pipe specifically made to work for boost could yield gains. Thoughts??
i would like to get one these kits before next season starts
You will be able to. A few more weeks and hopefully I will have the final priceing worked out and will have a summer price incentive.
Dave
. A few more weeks and hopefully I will have the final priceing worked out and will have a summer price incentive.Dave
i would like to get one these kits before next season starts
A couple issues I would like to address. Carbs and pipes.
New carbs could be made to be adjusted externally like other carbs in the past. It would all cost money and more R&D. Not all bad but, I need to stay focused on what we have to work with and stay inside that box, to a piont. I say this because I don't want to spend time on haveing new carbs made when efi is just around the corner. The stock carbs work very well when set up properly and need little adjustment.
The pipe deal. This could be a topic in itself. All I will say is with the factory pipe and a turbo the stock pipe still works much like it does without the turbo, but now it sees alot more pressure and cfm of air this is where the correct turbo comes into play. In with the charge, out with the charge. All components matched and tuned as close to perfect as could be expected. A pipe specificlly built for the turbo, engine, boost and all other variables would be way cool. Again, time and money. It might be a tad too one dimensional than most would be willing to deal with though. I'm sure it would make a significant gain in power. I know there are some companies makeing turbo specific pipes, but I'm not sure how specific. All I know is they are thicker. These would be for them Cat guys.
Very good discussion I hope it stays this way and we can all get some more insight. Thanks for all the questions and interest. Keeps me thinking what the consumer is going to want.
Dave
New carbs could be made to be adjusted externally like other carbs in the past. It would all cost money and more R&D. Not all bad but, I need to stay focused on what we have to work with and stay inside that box, to a piont. I say this because I don't want to spend time on haveing new carbs made when efi is just around the corner
. The stock carbs work very well when set up properly and need little adjustment.The pipe deal. This could be a topic in itself. All I will say is with the factory pipe and a turbo the stock pipe still works much like it does without the turbo, but now it sees alot more pressure and cfm of air this is where the correct turbo comes into play. In with the charge, out with the charge. All components matched and tuned as close to perfect as could be expected. A pipe specificlly built for the turbo, engine, boost and all other variables would be way cool. Again, time and money. It might be a tad too one dimensional than most would be willing to deal with though. I'm sure it would make a significant gain in power. I know there are some companies makeing turbo specific pipes, but I'm not sure how specific. All I know is they are thicker. These would be for them Cat guys
.Very good discussion I hope it stays this way and we can all get some more insight. Thanks for all the questions and interest. Keeps me thinking what the consumer is going to want.
Dave
