Nytro max boost on 100LL

[BOOST]

So at 5000ft to 10,000ft and running the Nytro on a GT25 what would be on the safe side as far as max boost with 100LL without the shim??? Would a guy be better off with the GT28?? Or is the head shim a must???

Just trying to get quick throttle responce and 12-14lbs of boost max not looking to run with the big dogs just a fun boondocker with lots of hp. Not into the supers they are great but I like the turbo they never stop pulling on the top end.

Thanks as I'm sure this has been asked before.

 

[HAMMER]

Not into the supers they are great but I like the turbo they never stop pulling on the top end

I know for a fact that properly clutched and setup super will pull hard from idle all the out the top....because mine does.... ;-)

If you're running a 25 at 10,000ft :exc: you'll regret not having bought the 28 (CFM)

Boost/Octane calculator says 14lbs for the Nytro at 5000+ft.
http://www.ty4stroke.com/viewtopic.php?t=23214

 

[BOOST]

Thanks hammer. Just seems like the Turbo pulls so good from what I have seen the super does work great though love the stump pulling bottom end they have would just like a turbo.

 

[snowy1]

yep you really should go gt28 for 10,000 ft.

 

[BOOST]

Thanks ok 28 now should I run the head shim to keep the snap and higher boost or lower boost without shim??? Just curious to know what boost I can run with and without and what the diference would be.

 

[snowy1]

the calculator says 12lbs 99 octane at 5000 ft. 97 octane at 10 lbs. with stock compression, I would not go over 10lbs to be safe, from what I have been hearing the throttle response with the head shim is very good, so I will be putting in the head shim for a safety margin and then I can turn it up to 18 lbs. if needed on 100 octane. your decision on what you want to do.


existing 11.10 82.00 66.20 122.00 58.00 3.00 1048.85 0.02 2.68 31.93 11.10 9.23
new 11.10 82.00 66.20 122.00 58.00 3.00 1048.85 0.02 2.68 31.93 11.10 9.23



base hp base dynamic comp ratio base octane altitude boost new comp ratio octane hp after comp drop hp after comp &alt hp after comp, alt& boost
130.0 9.2 88.0 5000.0 10.0 9.2 96.9 130.0 110.5 198.9
130.0 9.2 88.0 5000.0 12.0 9.2 99.1 130.0 110.5 216.6

 

[HAMMER]

Boost/Octane calculator reads in R+M/2 or AKI and it's conservative ... that's how I came up with 14lbs above 5000ft ... 100LL (Avgas) 100.5 MON and 103.2 RON (101.5 AKI) ... but like they say "It's better to be safe than sorry" ... so maybe I should have posted it as less than 14lbs would be max boost on 100LL.

 

[Blue shadow]

What about 22 psi at sea level with stock pistons .Would 110 oct do the trick.C ant get the cal to work on my computer.

 

[snowy1]

I would not run 22lbs on stock motor at sea level with out pulling some timing.the calculator says 108.8 for rx1 so I would say no to the 110 as most 110 ratings are only 105 octane.

 

[Blue shadow]

It says 110 oct on the 45 gal drum .That is pure polaris fuel.Thanks

 

[BOOST]

Anyone else

 

[powder muncher]

If you go with stock engine 12 pounds will surprise you, about the same power as 14 with the shim and probably as much as you should pull to be bullet proof on long pulls ( with 100LL) My RX1 experience.
22 pounds on stock engine internals is insane like looking for mod 2 stroke
reliability in a 4 stroke :ORC

 

[BOOST]

All I am looking for is a powerfull Boondocker on 100% LL. Not interested in 16lbs of boost 14 is max

So would it be harder on the motor with shim and 14lbs of boost or without and 12lbs what is going to have more power

 

[TWIN TURBO]

It says 110 oct on the 45 gal drum .That is pure polaris fuel.Thanks

You have to be careful with octane ratings! You need to know what rating the fuel company is using. VP uses what they call MOTOR Octane which is the most appropriate rating for racing engine especially for turbo and supercharged engines. Sunoco uses what's called a ANTIKNOCK Index or Pump octane as some would say, same as you see on the pumps at the local gas station R+M/2. Thats the average of Research octane, a rating which was used years ago in lower RPM and load engines a higher number, and MOTOR Octane, thus the R+M.
A stock engine at 22 lbs of boost better be using at least VP C16, 117 Motor octane. Better to remove some timing also as someone said earlier. Your flurtting with disaster in either case, 22 lbs on a stock engine is a little high in my opinion. Good luck.