All engines demand a different temperature to perform at full potential. Better to do carb adjustments by 'ear' and eye... seeing that in full acceleration, your car leaves by the exhaust a small trail of smoke will show you that's is healty, lean it accordingly this and don't focuse only in temperature readings.

Two engines of the same brand and model should not perform equally at the same temperature. Found one Sirio that refused to perform well under 120ºC temps (Sirio mills love to go slightly hotter than Nova ones) and other loved to go at 135ºC.

thanks corse-r!

It is absolutly correct and I am personaly agrre 150%. Different brands has different parameters when engine start free up for best performance. It is mostly related to piston material properties-better properties ( less temp expention-less running temperature.) Also it has something to do with tapering of the sleeve. So basecaly we can say, temperature of run related to piston/sleeve constraction designs.
This is why one of most important issue in engine's design is constraction of p/s set and takes a lot of time to get right set ups-material properties, tapering etc. Big developments and not always sucsesefull from first shot.

I see that gearing down will help acceleration and the Sirio to get into it's powerband, but will top speed suffer on large tracks? Mine is a dog right now, not real happy since my OS CZ-Z out performs it so far. Runnning a legal .12 in an R40 with stock gearing, RD Logics one piece legal, and NR C6 plug, on O'donnell 20%. Getting my @_$ fed to me currently.

Readjust your clutch to come in later, also buy the Mugen grey shoe it will fit.

Tks for the reply. I already have it engaging pretty late. I will try a little later. It just doesn't seem to get to full rpm. I got the 2 spd to shift after about 60-80' but sometimes it won't reach the speed to shift. If I set it to shift earlier, it also bogs down. Feels like I'm running an old Kyosho .10. With the wheels off the ground it screams. Got a 15 tooth 1st pinion and an 18t 2nd on order.

Yes it will, and top speed won't suffer, you'll get that engine into it's powerband.
I did three things to my Sirio S12 EVO2:
First: get one shim out from the head to run with 20% nitro.
Second: I normally run my Nova based engines with 14-48 on first gear, and 17-45 on second gear. I had to go to 14-49 and 17-46 with the Sirio. (Yokomo GT4 with Neo Centax Clutch)
Third: Use Novamega 2182-TPO3 pipe at 97mm
After that I set a new track record 3 weeks ago (still unbroken)

Now what do you mean by large tracks??, How long is the main straight??
Just see what gearing are the fastest guys using at your track with Nova based engines and just go one more tooth shorter with the Sirio and try.
Hope this helps
AFM

How is your carb set at now??
AFM

The straight is about 150'. My carb HSN is about 5 turns out and the LSN is about 2 1/3 turns out. Funny thing is, from what I've read, the LSN is even with the end of the slide. Mine is way past the end, by like 3 mm. If I back it out to even, I think the low end will be way too fat.

My EVO2 ended up with full power, and running like the Beep-Beep Bird with 5 3/4 out on the HSN and 3 7/8 out on the LSN, and at that point it is flush with the slide end, and engine temp is between 100°C to 120°C. with air temps around 25°C to 28°C, and humidity at 80 to 85%.
Your straight is about the same as mine (155ft), and i run my Evo2 (with the internal gear ratio of my Yokomo) at 7.0 drive ratio on first gear and 5.76 drive ratio on second gear for 63mm dia. tires allround.
To calculate what combinations you need, what you have to do, is divide the number of tooth from your spur and pinion at each speed, and multiply it by the internal gear ratio of your car, and you'll have your final drive ratio for each speed. You will have to correct one tooth up or down on your spurs according to your tire diameters.

Hope this helps
AFM

Thanks for your help, AFM. R40 stock ratios are 7.263 1st and 5.734 2nd. Right in the same ball park as yours (even lower 1st).
I'll even try backing out my LSN to even and see what happens.

Don't forget to take one shim out of the head......and i forgot to tell you that i'm using a Novamega 2182-TPO3 pipe at 97mm.
Good Luck
AFM

AFM is right.

Regarding the pipe. Make sure your pipe is suited to the engines power band. Choosing the wrong pipe really hurts the engine and stops it producing its full power capability.

But you have hit on something else when you mentioned backing out the low end needle. It is possible that you have set the needles too lean and are going beyond the optimum powerband range. If you reach and pass the sweet spot before the car is ready to change gear you will get the same effect that the engine is dead.

I was confused about the low end needle. I was looking again and the screw head is even with the ball end of the slide.

Isn't 97mm a very short tuning length? Shorter for top end and longer for more bottom end power, right? My RD Logic is about 150mm from the exhaust port to the baffle, and it is a short pipe. I can't imagine a pipe 30% shorter than this.

Every pipe has its powerband design, so I use the lenght range recommended by the manufacturer and try different lenghts until i find my "sweet spot" for the engine and track.
I use the RB method and it has proven me good results, at least with Nova (non-in-line based pipes). I don't like very much in-line pipes , because they are supposedly tuned for the best...but leave you no tuning options. Go to following link to see what i mean when I say 97mm.

www.rbproducts.com/rbww/pipe...ifoldlength.htm

It tells you how to measure that lenght, and in their pipe product description it tells you the min. and max. lenght suggested for each pipe.

AFM