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Old 06-06-2008, 02:20 AM   #1
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Default Chaps any advice wanted Please Novarossi ?

Hey all,

Just wanted to clear up a few points if possible,

Im currently looking at buying a new motor quite possibly a novarossi 21-5k or the 21-7

Now im not sure which one to go for but im leaning towards the 21-5k, and im going for the novarossi efra 3005 pipe

Now ive heard rumours your only meant to run these on a max of 25% nitro? is this correct as i run 30% currently but if i can only use 25% thats no biggy

how likely would it be to get the elusive 10min run times at the moment i use a os speed in the x1cr and get around 9max with a jp4 and odonnels 30%

I know its dependant on all sorts of criteria but has anyone managed it

Cheers all
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Old 06-06-2008, 12:27 PM   #2
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Those are all hard questions cause it varies alot on your track. I can tell you that if you wanna run 30% fuel all you have to do is add a extra head shim which probably will come with your new engine.

As far as which engine... generally less ports=more low end, more ports=more top end. So if you have a big open track I would do the 21-7, if you have a smaller track where you are in and out of the throttle alot i would do the 21-5.

Hope that helps.
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Old 06-06-2008, 06:35 PM   #3
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The 21-5k should be able to attain 10 minute runtimes. It will depend on how much throttle you use and tuning. In general, add 0.10mm shim for 30% fuel. You can generally rip it out after break-in or 2 gallons. I would suggest replacing the rear bearing also at 1.5 to 2 gallons.

You current setup in your car has been ran with 15min+ runtimes, so if your getting 9min, your tuning, driving style or track maybe determining your current runtimes.
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Old 06-06-2008, 07:18 PM   #4
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They should run fine on 30% without adding a shim. I have run as much as 33% on Nova's with stock head clearance. Yes they are set-up for 25 but they are also set-up on the safe side so 30 is no problem.
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Old 06-06-2008, 08:15 PM   #5
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My 21-5kt can get about 12 minutes in practice (truggy), and depending on how I am racing, I can get 9:30-10:30 on a tank. If you are going to get this mill, I would advise you to get the turbo head. The turbo head really smooths out the engine, gives it a bit more oomph, and tunes easier imo. I run OD97T plugs in mine, 1 additional thin shim, 30% fuel, and 53 pipe...oh yeah, don't expect it to run with that Speed of yours...it does not have a top end like the Speed does, but the powerband is smooth and it pulls good all the way to the top, but the Speed is definately faster imo
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Old 06-07-2008, 01:00 PM   #6
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Thanks Chaps,

Greatly aprecieated
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