Maximizing an OS 18TZ
03-29-2008, 10:44 PM
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Maximizing an OS 18TZ
OK ... first we need to get by the "it's a car engine"! I know some have used this engine in sport hydros and riggers and some of the riggers are even air-cooled! I know I have seen some of you that are trying the car engine also (JD?).
I know it is designed for 20-30% nitro (according to the instructions) and I can testify that it develops A LOT of power! BUT... you know how it is - never enough!
I carefully monitor rpm, head temperature, and GPS speed on my Sport 20 (I know ... why don't I just put an actual 20 in it?).
I am running 30% nitro and decide to try 50%. First off, it doesn't allow me to richen it up more than about 1/4 turn (doesn't higher nitro take a richer needle? ... hmmm...). Then I run it a few times - only difference is a little hotter head; speed and rpm are the same! I couldn't believe it!
Do I need to change the intake timing for the higher nitro?
If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
I know it is designed for 20-30% nitro (according to the instructions) and I can testify that it develops A LOT of power! BUT... you know how it is - never enough!
I carefully monitor rpm, head temperature, and GPS speed on my Sport 20 (I know ... why don't I just put an actual 20 in it?).
I am running 30% nitro and decide to try 50%. First off, it doesn't allow me to richen it up more than about 1/4 turn (doesn't higher nitro take a richer needle? ... hmmm...). Then I run it a few times - only difference is a little hotter head; speed and rpm are the same! I couldn't believe it!
Do I need to change the intake timing for the higher nitro?
If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
03-29-2008, 11:57 PM
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RE: Maximizing an OS 18TZ
i cannot tell you how mine will work in my rigger yet because we have hard water right now , but i took the option of water cooling my tz, changed to a rotory carb off a cvrm .18 and removed the pullstart , so i am also using a regular glow plug now and changed the head volume and set the clearence at .006 stock it was at .018 so that helps out too. good luck and keep us posted on what you find out.
terry
terry
03-30-2008, 04:40 AM
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RE: Maximizing an OS 18TZ
I am looking forward to your results - I am VERY HAPPY with my 18TZ!!!! I rigger would be an ideal candidate for keeping the air cooling, if that is still an option for you. I know that some people are having good luck with the air-cooled 12TZ.
03-30-2008, 07:40 AM
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RE: Maximizing an OS 18TZ
ORIGINAL: 007clint
........If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
........If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
03-31-2008, 01:29 PM
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RE: Maximizing an OS 18TZ
ORIGINAL: 007clint
OK ... first we need to get by the "it's a car engine"! I know some have used this engine in sport hydros and riggers and some of the riggers are even air-cooled! I know I have seen some of you that are trying the car engine also (JD?).
I know it is designed for 20-30% nitro (according to the instructions) and I can testify that it develops A LOT of power! BUT... you know how it is - never enough!
I carefully monitor rpm, head temperature, and GPS speed on my Sport 20 (I know ... why don't I just put an actual 20 in it?).
I am running 30% nitro and decide to try 50%. First off, it doesn't allow me to richen it up more than about 1/4 turn (doesn't higher nitro take a richer needle? ... hmmm...). Then I run it a few times - only difference is a little hotter head; speed and rpm are the same! I couldn't believe it!
Do I need to change the intake timing for the higher nitro?
If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
OK ... first we need to get by the "it's a car engine"! I know some have used this engine in sport hydros and riggers and some of the riggers are even air-cooled! I know I have seen some of you that are trying the car engine also (JD?).
I know it is designed for 20-30% nitro (according to the instructions) and I can testify that it develops A LOT of power! BUT... you know how it is - never enough!
I carefully monitor rpm, head temperature, and GPS speed on my Sport 20 (I know ... why don't I just put an actual 20 in it?).
I am running 30% nitro and decide to try 50%. First off, it doesn't allow me to richen it up more than about 1/4 turn (doesn't higher nitro take a richer needle? ... hmmm...). Then I run it a few times - only difference is a little hotter head; speed and rpm are the same! I couldn't believe it!
Do I need to change the intake timing for the higher nitro?
If I have this right, pipe length is based on rpm (to get the shockwave back at the right time) - so no higher rpm, no shorter pipe needed - right?
Sorry for all the questions but I am still trying to get all the dynamics down. Oh, so many combinations!
Thanks,
Clint
Hi there Clint,
the ideal pipe tuned length is a function of many things, RPM you want it to work at, engine timing, exhaust gas temperature, and NITRO content, being among the things that can make a difference to tuned length.
Generally, an engine running higher nitro will have less compression, so maybe a couple of shims might help you out.
With a higher nitro fuel, the tuned pipe is effectively much shorter, so maybe you actually need to increase the length of your pipe to get the effect you require.
Also, you need to ensure your motor is running hot enough to ensure that the nitro is in fact burning.
If helpful I can point you in the direction of some good web pages that explain tuned pipe theory further so might help you fathom better the interactions between various systems.
Glenn
