Unfortunately I don't think there are any options for shortening the exhaust header. (technically a "manifold" is multiple headers combined into a single part, derived from the word "many-fold", so the word only makes sense when talking about multi-cylinder engines.) The stock header is a simple 90-degree downward bend and a 90-degree forward bend; there isn't any extra length to get rid of.

Good to know about the compression ratio. That's something I can continue to experiment with, then. Would you recommend removing the shim on top of the sleeve, or the shim under the lip of the sleeve, as the next step? I honestly can't decide whether the shim under the lip of the sleeve is actually increasing the exhaust and transfer port timings enough to matter.

Though I will say the shims definitely serve as gaskets as well; I had a different engine that was blowing bubbles under the cylinder head, and it didn't stop until I sanded-down the top of the sleeve a bit to ensure it was flat and then tightened the hell out of the head bolts. I actually had to tighten the head bolts while the engine was running so I could see where the bubbles were coming out, and tighten the bolts accordingly. The good news is it never leaked again after I did that, even after taking the engine apart a couple times.

The problem is that over 90% of the drivers have no clue, but if it is used in high end racing in any kind of motorsports it must add a vallue so people are willing to spend money as if lower laptimes can be bought. Ceramics are only needed if you are at the top and need that 0.1 sec better laptimes to get on podium. To get there at 0.1 sec off the top it must come from your fingers, setup knowledge and ofcourse good engines but no high tech parts like titanium, ceramics etc.

The only reason for an avarage driver to use ceramics in engine and car is that they can (can! , not do) provide a better lifespan above steel but even then with cheap steel bearings it is hard to get an affordable lifespan advantage with ceramics.

That stock manifold is probably hurting you .... as I say that is super critical to making the best power, even 2 extra mm can mean a 20% loss of power or even worse

I could cut the end of the header (or the end of the pipe) slightly shorter, as the Novarossi pipe is slightly longer than the stock pipe that came with the car, and they are attached with a silicone tube instead of springs and a gasket. But how would I know how much to cut off? It seems like I would need to know both the exact max RPM of the engine as well as the exact exhaust velocity in order to shorten the exhaust by the right amount.

It's always annoyed me that nitro engine pullstarts use bronze bushings instead of ball bearings. Bushings wear out and get sloppy. I realize there needs to be a solid surface for the pullstart shaft to seat against to produce an airtight seal, but the pullstart shaft still ought to be *supported* by ball bearings as it spins.

Well, my HPI .12R SS engine has a press-fit bronze bushing in a standard size instead of a cast-in bronze bushing that can't be removed, so I decided to do something about it:



I also cut a second notch in the opposite side of the pullstart shaft so it would be balanced. That should reduce vibration a bit, and hopefully reduce imbalance-induced friction a bit too.

Hello, ive been reading your posts about the engine. I feel that your quest for the most power out of that engine is well, a waste of time. A low line nova rossi like the ison line($150-200) with all the work you have put in would show much more fruit in terms of speed. You are going two different directions at the same time. All the pull start parts off the end of the crank are heavy and alot of drag, even if you put bearings in place of bushing. If you were to mod more of a race engine that has proper piston sleeve fit amd the right touches, your car would be much faster for sure.

But it wouldn't have a pullstart, and so I would never use the car. A "better" solution isn't actually better if it doesn't get used.

The weight of the pullstart shaft is a few grams. One of the wheels axles weighs more. The pullstart shaft spins faster, but that just slows down acceleration, it doesn't reduce the top speed.

It isn't a waste of time because I'm enjoying myself and learning useful information. This is a hobby, not a job. Even if I wanted to do RC stuff for a living, my current job already pays me more than an RC job ever could. If I can tell myself that I made this little engine work as well as it possibly can, then I will be happy.

There is a rotostart.

http://www.novarossi.it/2012/index.p.../sturm-rt.html

I would still have to carry a rotostarter with me. With a pullstart all I need is the glowplug heater. Even the Traxxas EZ-Start battery pack is bigger than I'd like; the only reason I tolerate the EZ-Start for my T-Maxx is because it came with the truck. Come to think of it, maybe I should replace that with a pullstart too.

Interesting, that Novarossi engine has a max RPM of 38,000. I figured a Novarossi would peak at 45,000rpm or higher.

Only numbers...... do not get fooled by them.

The universe runs on mathematics. Why would numbers fool me, unless the measurements were done incorrectly?

Because the numbers are not based on calculations or measurements....

Are you saying the RPM rating for that engine is made-up? That's disappointing; I would've expected better from Novarossi. If their reputation is deserved, then they don't need to make up impressive numbers to sell engines.

The RPM is depending the load so you can not give any real numbers. Novarossi uses these numbers to show the differenses between their own engines which is made with better performance.