Super Charging and how to

[hudmut]

I wounder if any one can help me.

Over the last to years iv not had the time to get a engine completed as iv been building my cnc mill along with others things.

So i want to get my new mill to make me some thing in return. Iv settled on making a twin of my last engine witch was a NE15 4 stroke single. So I'm adding one extra cylinder and by doing this I'm left with a big open space on the top of the crank case i would love to put a super charger on there.

This is wear i need your help has any one ever tyred this or do you know wear i can find some plans for a charger or have ideas on the wrong or wright way of going about this if not what would you put on top of the crank case.

Im sorry if my typeing is hard to read im not very good at this im a lot better with the hand wheels on machines

 

[stevehuckss396]

I have plans to try a roots type blower in the future. I have not tried anything like it before now. There are superchargers and turbos for RC engines. Maybe google those and you might be able to draw some info from those.

 

[ariz]

hudmut I don't know anything about supercharging a model engine, but I know enough about doing it on a real engine
so, when you eventually will have it completed, remember that the engine needs very much more fuel to run and the ignition must be retarded several degrees or the engine stuns
at least in the real world

 

[kcmillin]

Hudmut, I have some limited experience in making a supercharger for a nitro R/C engine. I will second Ariz and say you will definetly need to add more fuel to the mix. I had the mixer needle turned 2-3 turns richer than usual.

My supercharger was an impeller style, ran from the flywheel on a 1 to 4 ratio. Thats spinning around 100,000 plus RPM. the imepellor size was 1 inch and the blades were mostly carved by hand with a dremel tool. Many Many, hours it took. Sadly I don't have it anymore, I sold the R/C car I had it in. (I would rather make my own)

Also, life expectancy of the engine gets shorter, about 2 gallons and the piston and cylinder were shot. This could also be due to my shoddy work on the supercharger, I started with brass bushings and most of it went through the engine.

Hope this helps.

Kel

 

[chillybilly]

Hi stu ,

Done some work on a big roots supercharger over the summer ,nothing special on end but was terrified to learn it takes 120 hp to run the thing .Not such a major when you got big hp on tap ,but something you may want to consider regards the plan .Cool idea ,will sound mega .......

 

[Lakc]

Hi stu ,

Done some work on a big roots supercharger over the summer ,nothing special on end but was terrified to learn it takes 120 hp to run the thing .Not such a major when you got big hp on tap ,but something you may want to consider regards the plan .Cool idea ,will sound mega .......

Making an extra 2-3 hp at the cost of one sounds like a great idea, until you realize you have to engineer a tiny power takeoff good for one horsepower. There is a valid reason those big blowers have 6" wide belt drives.

 

[hudmut]

Well this is all good news as of yet no one has said it cant be done and whats the point.

Iv had a bit of a look about and come up with a few ideas with what i need as well as want to do.

The only thing I'm short of is what size to make the charger I'm sort of thinking make it a nice size to fit on top of the crank case and then gear it to what psi i want to run it at making the vanes is going to be easy for me as i can get to use a wire eroder so that bit is sorted. That brings me on to the next bit i was going to drive it from the back of the crankcase I'm not to sure if I'm going to make a built up crank shaft or a sort of a catch plate/PTO off the end of the crank pin. Whats your ideas on this as there is going to be no room up front for the blower belt with there being to cam belts all ready.

As for the fueling side of thing this is the next step i need to read a bit more on should i put the carb before or after the blower and as for the carb i was going to use one of my OS 90 heil engine that.

Iv not even looked in to the timing and ignition side of things yet but i have had a look over a mates 150 twin aero engine that's looking like the sort of set up i was going to use.

And here's a pic of the crack case all done and ready

Hi will what you been playing with ?

 

[chillybilly]

Now there is a question :big:

Been in the shed bikes dragsters steam engines ,just makin a start on the nemett now ,been a while .

On the supercharger front i have been thicking of a small one for the Ktm ,at work we have small scroll comps plan was get the vains /scrolls out of an electrical scrapper one and see what i can do with em ,issue is cutting the body open to get at teh goodies within .
Will have to catch up

 

[hudmut]

Hi Will

If your after a small charger aprilia put one on a small 125 4 stroke scooter i had one on my monkey bike there a good size there sort of like a baby oil pump i got mine up to abobut 8 psi with out to many problems :

As for the nemmett are you going for glow or petrol and water or air cooled

 

[jpeter]

If looks is what you're looking for, which might be the case in a small homebuilt engine, build it to look good and don't worry too much about whats inside. I think most small homebuilts don't perform at max anyway. Check out a few on youtube. You can tell by the sound lots are faked out.

 

[Lakc]

The only thing I'm short of is what size to make the charger I'm sort of thinking make it a nice size to fit on top of the crank case and then gear it to what psi i want to run it at making the vanes is going to be easy for me as i can get to use a wire eroder so that bit is sorted. That brings me on to the next bit i was going to drive it from the back of the crankcase I'm not to sure if I'm going to make a built up crank shaft or a sort of a catch plate/PTO off the end of the crank pin. Whats your ideas on this as there is going to be no room up front for the blower belt with there being to cam belts all ready.

Well, if you go the "positive displacement" type pump the math is considerably easier. If your pump is half of the engine displacement you can develop a max of 1 bar boost with a direct drive, remembering the engine only sucks air every other stroke. If your positive displacement pump is 1/4 the size, direct drive gives you 1/2 bar, or double the pump speed for a full bar. Although mathematically calculating the displacement of a roots type blower will be anything but easy.

If you go to the centrifugal pump route the math is way beyond me

 

[rcfreak177]

Hi hudmut, I have sent some plans to yr email address,
I was meant to send the supercharger plans but accidently sent the whole set for a 1/4 scale V8, There are bits and pieces missing from the drawings, I am actually working on this project at the moment and have managed to fill in the blanks on my end.
Good luck, Please keep us all posted.

By the way, there is no copyright on the plans, I had to pay 100 bucks for them off Ebay, I would ask to please be sensible with the distribution of them.

Regards Barry

 

[gmac]

I ran across this site when looking for info;

http://www.blowerdriveservice.com/

They service the real thing but have some technical info that may be useful to you in building a model version. Check these sections - "Tech Info" and "Recommendations";

http://www.blowerdriveservice.com/recommend.php

This does a blower build-up that gives some insight into what's critical;

http://www.dragracingonline.com/technical/vii_12-blower-1.html

I couldn't find much on the internet so good luck! Keep us posted, at some point I'd like to build a model blown fueler engine too.

Garry

 

[gmac]

Following on from Steve and Kel's comments about R/C superchargers I ran into this;

http://www.rbinnovations.com/category_s/3.htm

http://www.rbinnovations.com/articles.asp?id=134

http://www.rbinnovations.com/articles.asp?id=137

If you want to get right carried away try this; (now you've gone and renewed my interest in this subject :big

http://journals.pepublishing.com/content/k624633w57277h32/fulltext.pdf

Garry

 

[hudmut]

Thank you all my head is starting to spin with all the in put and info im trying to take in here.

Well it seems i sort of have a plan of attack now. RcFreak has come up with what i needed so i can now get some thing in to CAD and work out wear and how im going ot mount and drive the blower. As for working out the size and speed im going to run at im still a bit unsure of. But i will admit im a bit in over my head here making the blower im more than happy with but working all the bits and bob's out is proving harder that i thouhgt.

On the up side i got the cam box's machined out to night.

Should i be putting the pics of the build some in a diffrent place ?

 

[Drei]

Hi,
I dont exactly if some one already questioned but, has anyone have or know from where I can find small turbos plans for my medel ic engine; the Lynx NE 15. . .
Thanks

 

[nesikachad]

Years ago I started my machinist career in autoracing in S. California. I've been around a few FI engines here/there. I recently sold my 2004 GTO with an LS1 that I drained a savings account into.

I had a Magnuson supercharger in this car and here's what I learned over conventional roots style superchargers. I'll cover the bits surrounding a positive displacement blower (roots style) as it's what I'm most familiar with.

A straight vane rotor system is fine if the engine goes from 0 to WO with little concern with what happens in the middle. This rotor design creates a pulsation in the intake tracts that causes the engine to surge quite a bit at idle.

Generally, the more helix you can create with your rotors the better the drivability will be. Just something to consider.

Fuel delivery is everything with an FI engine. Make it robust and overkill the snot out of it.

Overdriving a blower works to an extent. It also turns HP into noise and heat.

As stated, pulling timing is also needed. This is a good thing. It means your chamber is more efficient now. The plug doesn't have to fire as soon to make power.

Boost is not synonymous with HP/TQ either. It's a direct function of how efficient/inefficient the intake tract/exhaust system is.
Exhaust is another item that should be paid attention to and this leads to camshaft design.

Blower cams need not be the psychotic sounding shaker cams that make a hot rod "cool". You just need more exhaust duration/lift and to tighten up the overlap a bit so that your not pissing the intake charge out the exhaust when it opens. (remember, your pushing fuel/air into the engine now. No longer the need to rely on changes in atmosphere to do the work for you.

Last. EVACUATE your crankcase. Even better: Pull a vacuum on it! Your rings will love you for it and you'll make more power.

Good luck with your project. If you can do anything to mitigate the buildup of heat DO IT.

 

[Lakc]

Last. EVACUATE your crankcase. Even better: Pull a vacuum on it! Your rings will love you for it and you'll make more power.

I have argued against that one when it first started to be popular. I have since been told by a trusted source, who actually owns a Sun dyno, that it does work, and I accept that.
I still find myself arguing against most of the reasons people seem to think makes it work, and am interested in any actual evidence behind the principle.

 

[nesikachad]

From 1992-1997 I worked in autoracing as a maggot and eventually a machinist for Paul Rossi Performance Engineering, Richard Conley racing engines, and Bill Craddock racing heads.

Here's what it taught me:


A 5 stage dry sump oil pump will pull around 30" of vacuum when the engine is above 10k rpm in an nhra competition eliminator engine. This negative pressure means less air to churn oil into foam and that means more reliable lubrication to mains and rods.

I know my car picked up 20hp on the dyno with the addition of an x ternal evac pump. (Basically a reworked smog pump from a mid 80s dodge pickup)

I know a c altered competition eliminator engine makes aroun 35 more hp with a good vacuum in the crankcase as well. This is based on what I saw with my own ees on a superflow dyno.

Think of it this way: if you are an engine displacing "X" cid you are also displacing below the pistons. If you pull a vacuum down below that's less work when the piston goes down. This is especially important for 4 strokes since you only get a bang once every 4 cycles. The less soup for the crank and rods to churn through the better.

If the pressure down below is in doubt the good ol 2 stroke proves it since they depend on this pressure to lubricate and run.

An FI engine is more prone to gasses passing around the sealed surfaces on rings and liners. A vac pump will help evacuate the pressure in the crankcase. More pwer and more reliability is the result.

 

[Lakc]

Thanks, but for every piston helped going down in the bore by negative crankcase pressure, an opposite number are going up against it, so it seems like it would be a wash between them .