SilverM3:

I used this motor (12-3CT)for the nats last week. It has a large power window and easily made time despite not being fully broken in. Comparing it to OS Speed motors at the track, this motor had better rip at the bottom and mid range but lost out a little in the top. I was geared for this and didn't have time to experiment with pipes. On top of the great power and mileage this unit gave me, after a gallon or so of fuel, the motor could still use some running in. I predict this motor will last quite a while. Hope this helps.

Do i need to replace the crank if i convert the LS5 to an LS3? or just the Piston & liner?

did you use the EFRA 2630 exhaust pipe???

piston/sleeve only.....

i've just drop in a 3port p/s into my 3 year old nova s5...without replacing any other parts...after doin some breakin in and raced it yesterday it works pretty well...

The OS is not a true ABC PL set and will loose the pinch very quickly if overheated. Go for the 12-3

Cheers

What do you mean it's not "True ABC" ?? The Specs for the engine says so:

FEATURES:
-Natural aluminum construction Nine fin blue aluminum cooling head
-Two-piece turbo cylinder head with 29mm innner and 49mm outer head
that adds extra area for more efficient cooling
-Slide Carb 11H - 3 needle slide valve carburetor with ROAR/IFMAR legal 5.5mm carb restrictor
-Rear Exhaust
-ABC construction, Aluminum piston and Brass liner that is Chrome plated
-High tensile A7075 "knife edge" aluminum connecting rod double bushed for friction-free operation.

Don’t confuse compression with pinch, Sleeve Pinch is not that important contrary to popular belief. The question is how well does it seal as soon as the piston starts to close the exhaust port and if it holds compression after you roll it to top dead center.
Place a few drops of after run oil trough the top (removing plug), then place plug in place, then roll piston to top dead center and listen and look for air bubbles through exhaust port. If there’s none, then your engine still has compression, even if it has no pinch.
The fastest team motors we have, have zero pinch.

AFM

I am not knowledgable as anyone of you. But, my exp is that OS TZ seems to be quite durable. I had more than 8 gallons on TZ 5, and I still see a lot of compression.

My bday is coming up, and my wife finally "allows" me to buy a new engine. I like OS TZ tuned better, because I am used to tune OS engine. Plus 12-3C seems to me is a better deal, cheaper and equal in performance. But, I heard NovaRossi is harder to tune than OS engine. That is why I would to hear some comments regarding these to engines. Thx.

Not sure were you are getting that info but OS probably make one of the finest ABC P/L ever. Granted they were never huge on the car scene other than off-road compared to other known brands but their aero engines have been the class leaders for many decades.

any one know the difference between all the the 12 plus 3 models
is it turbo non turbo ceramic and non ceramic is this right

yes,
plus 12 - 3 (non-ceramic, non-turbo)
plus 12 - 3C (ceramic, non-turbo )
plus 12 - 3T (non-ceramic, turbo)
plus 12 - 3cT (ceramic, turbo)

1603 - non-ceramic rear bearing
1606 - ceramic rear bearing

No, I used a JP EFRA 2620. Ddin't have time to test the 2630.

just to clarify......

when Novarossi means NON TURBO, it refers to the crankshaft, not the glowplug, the non turbo shaft is EFRA legal and its tunel is smaller than the turbo style, which is not efra legal.......

ok guys i have a Novarossi RR12L3 hotmod engine. What is a good pipe and header combo for it?

Here is the list that you can choose from
JP EFRA 2620
Nova Rossi EFRA 2630
Skyline VR 12 Plus ROAR LEGAL
Vantage carbon pipe ROAR LEGAL