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Last edited by blackjack_original on Fri Jun 06, 2014 8:19 pm, edited 1 time in total.

You can supercharge a 2 stroke, but it wont work. The exhaust port is open at the same time as the intakes. You will be blowing most of the fuel straight out the exhaust and leaving bugger all to ignite and lubricate the engine.

The result, a less powerful engine and premature failure!

Anything above 30% nitro on a big block, 0.20ci and above, is only going to fry the engine. Oil should be synthetic for maximum performance (mineral for longevity) and less than 15% of the fuels mixture. The rest is made up of methanol...

You are better off port matching the exhaust header, smoothing out the crankcase to port surfaces and knife edgeing the intake on the crank, DO NOT widen the crank port as this will alter the timing of the engine. You can also remove shims from the head to increase compression.

As Disco has already stated, you will also need to determine the best gearing for your application. Try and have it at maximum rpm as it crosses the line.

you are assuming that in a non forced induction setup that 100% of the exhaust gas is leaving the chamber!! it doesnt, so adding the forced induction does make sure that as near to 100% of the exhaust gas is pushed out the chamber, leaving nothing but nice clean intake charge to burn in the cylinder... 2 stroke diesels used this principle for years.

also you say you will be blowing all the fuel out the exhaust?? no, you may have some of the intake charge going out the exhaust, but since you are still running the same a/f ratio, if you have a crankcase full of air, infact, you have more air than what is normally in the crankcase due to it being under pressure, then, you ALSO, have more FUEL than normal in the crankcase... more fuel=more lubrication, cleaner gas in chamber=more power

my 2c

This idea definately works, you'll get an extra 30% power for a heafty price of $300 but then add on the cost to buy a new engine every month (200-400) as they simply dont have the durability.

http://www.rbinnovations.com/catalog/pr ... 6f9369529c[/img]

 

 

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You dont undertand the principles of nitro 2 stroke engines. Less fuel with a high content of nitro = more power. You can buy forced induction for these vehicles and it is known to make no difference, other than to make it look bling bling.

The principle of forced induction doesnt work on an engine where the intake and exhaust ports are open at the same time. BDC = all open, TDC = all closed

well, think about it, doesnt that principle still stand, you say you need a leaner a/f ratio with higher % nitro to make more power, what part of supercharging it do you think will affect the a/f ratio or nitro content %???

none, you will just be burning a larger volume of intake charge each time...

as for intake and exhaust ports being open at the same time with forced induction, well, have you ever noticed the huge amounts of overlap in a supercharger spec camshaft, its all about flushing out the cylinders on overlap to prevent burnt exhaust gases diluting the new mixture... one example where its not preferable to have large overlap in forced induction is with a turbo, this is only due to the fact that you will have usually 2 times the inlet manifold pressure present in the exhaust manifold, which, with overlap causes exhaust flow reversion... supercharger and turbo cams are majorly different..

thanks for all the input and ideas guys,

i might just stick with the gearing and stuff for a while, maybe experiment with the bolt on "superchargers" and high nitro fuels later on.

anyone got any little fordmods stickers i can stick on the car body?

running over 30% in a big block will fry it, I ask why? It will fry it if the engine comp is too high. It would only die prematurely if you didn't know what you were doing. Go research how much nitro boats run and you will see, and they run flat out, not for a short time like a car.

more nitro=more power=less lifespan for engine.

when running higher nitro you need to RICHEN up the mixture, in any case swapping between two different nitro content fuels will screw up the piston to sleeve wear pattern, which is extremely important.

you don't want to de-shim the head unless you are running really low nitro or the burn will go up the s**t and you'll loose power, most engines come set up for 10-30%.

A sign of too much comp is a peppered or shiny metallics on the glo plug, which is from detonation. It could also be caused bt too hot og a glo plug.

Running a nitro car is just like a top fueller, you gotta read the plugs and feel the temp. In the small scale that these things operate bolt on power is a waste of time, if you run higher nitro, tune it properly(ie, fuel, temp, comp, plug, pipe, pipe timing=header legth) you will be on the right track.

The way I've modded all my cars is Air filter first, then tuned pipe, then gear to suit that, then header length, then maybe a bigger engine, I've found SH28's to be good value they run well on 25-30% nitro.

What size and brand is the engine you have? What car?

 

 

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If the intake and exhaust are open at the same time, where do you think the intake is going to go? Straight out the exhaust port before it gets a chance to be compressed and ignited.

Super and Turbo charged engines dont have majorly different cams, you want all of the pressurised intake to be compressed, you dont want it to blow straight out the exhaust port... You dont understand 2 strokes and you dont understand 4 strokes, both n/a and forced....


LTD351T: 30% is a s**t load of nitro for an air-cooled RC engine. You would need an extrememly cold plug and a rich mixture to maintain a decent temperature.

Boats are water-cooled and thus run at a more regulated temperature, thereby allowing the owner to increase the nitro percentage and tune accordingly. Your not going to get the same results in a car, be it onroad or off. Boats generally run a much larger engine than cars (of which this topic is about) and the additional nitro is warranted in that application.

You can remove shims with no problems, like you say, if you know what your doing.

The vehicles I own are HPI Savage SS 4.6 and a Great Vigor which does a piss poor 80km/hr, the original engine was an OS .12CV that was swapped for an OS .12CV-R and the latest engine is an OS .15CV-R... which will be replaced by an OS .18TZ

In regards to your way of hop-ups, you are better off tuning the header length before you finalise the gearing

I run a mcoy #59 with 30%, thats a fairly hot plug, an OS 8 is a bit cold for it and it blubbers.

But that depends on the quality and nature of the engine, all the novarossi (top,rex,nova) will run better at 280-300+. And a lot also with the fuel, I've always run a small dash of castor oil if using synthetic, but the nova doesn't like that, it likes less oil like 10% only, and at least 25%.

About the nitro thing you are correct, but if it was a drag only car, you could run high nitro as its only going to get warmed up, then race, then stop.

We had my original S25 from the SS kit running at 440degs for about 5 full tanks continuosly, we couldn't kill it, and it was still going strong when my mate cracked its case and killed it. Composite carbies are great.

There was an Ausrc get together in the ACT about a year or two ago and my super hot s25 was the fastest by 2mph, the gain from running them that hard is minimal, but it will win races.

Header length will tune where the pipe comes on, so you could do it after or before a gear ratio change, my theory is that you gear it to suit what your doing then tune the pipe to get the boost where you want it.

Yeh, thats all well and good, but if you have tall gearing and you tune your pipe to pull your car quick out of the corners, then your not going to get upto speed very quickly.

So you need to determine what environment your car is going to be run in, setup the gearing for that environment and then fiddle with the header length to give you the best performance for that environment.

"In regards to your way of hop-ups, you are better off tuning the header length before you finalise the gearing".-did you change your mind?

LMAO... I must of had a brain f@rt and wrote down your method of setting the car up... good work South

lol

I used to play with these cars heaps but now with the real cars using up all the money I never use it anymore. Wish I had more time.