IcemanG17

funny you bring up RC engines.....I had a "built" 4.27cc engine made for my 4wd buggy on street tires with a 2 speed trans.....it was built as a low end engine and man was it....it did scale 1/4 mile in about 2.5 seconds..or about 0-50mph in 2.50 seconds...top speed was 55mph, mostly limited by the 35,000 max rpm on the engine....I was told it made 3 hp...and I don't doubt it....

It ran on 30% nitro that cost $30 per gallon....at least it ran for 12 minutes on 250cc!!

RKD in OKC

I had an rpm guage that you just pointed at the prop. It had settings for how many blades on the prop. Used it to tune the mixture for max rpms. The little 4 strokes are cool and can spin some really big props for a lot of torque, but it took a bigger 4 cycle to power the same sized plane. There was even an engine with belt driven overhead cams. The belt would break and the engine would crater. I also had a .53 cu in supercharged 2 stroke that was pretty hot making almost 3 hp. The idea for aerobatics was to get it a light as possible with enough power to hang it on the prop like a helicopter.

ptuomov

Here's a dyno graph from Dave Lomas. It's a supercharged S4:





I am eyeballing about 425 rwhp average power 4066-6100 rpm. If the dyno graph would run to about 6500 rpm, average would probably be meaningfully higher.

IcemanG17

here is the Estates latest dyno....while not even close to the boosted-big engine cousins also on this list....It manages to get around the track pretty decent with an average of about 172whp from 4000-6000rpm....

smith 928

What Psi is it running?

ptuomov

This dyno graph was produced with 12.5 psi at the top end, I think.

ptuomov

Ok, so i changed the boost control settings and whatnot and was able to move the average hp from 540 Dynojets to 545 Dynapacks in the x-1.5x range.