G35 1050 vs G42 1200 on a 13B - Best Choice for 600hp?
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Joined: Jan 2025
Posts: 190
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From: Alabama
"It might be worth having a chat with your tuner about what they'd recommend for a true 600 rwhp setup. You'll probably get a range of opinions, as injector sizing"
fueling and rotary power are pretty easy IF you have the actual data.
actual data being exact flow of your injector at a particular pressure
actual digital fuel pressure
injectors (primary and secondary) duty cycle
fuel mix (adjust for BTUs per gallon)
AI pressure
AI injectant composition
accurate air fuel ratio
do the math and you end up w weight of the fuel per minute adjusted to gasoline at 6.3 pounds per gallon.
for instance, a well race ported rotary needs 80 pounds per minute of air to make 600 rw rotary hp.
if we decide to tune at 10.8 AFR it is pretty simple to calculate that we need 7.4 pounds of fuel.
7.4 X 10. 8 = 80
a gallon of fuel of gasoline weighs 6.3 pounds (weight varies slightly w temp) so 7.4/6.3 = 1.17 gallons per minute which is 4429 CC per minute.
4429 cc for 600.... if you want any other number just do the math.
2215 for 300.
i run around 1000 CC of meth as AI. i simply BTU adjust meth to gas and add it in. water is negative BTUs but if you are running 300/500 it isn't much of a factor..
once you solve for the weight of your fuel used it is easy to come up w hp and torque. i have been doing this for 20 years, have checked it on dynos and it is generally within 20 hp. this is dynojet hp SAE. obviously different dynos show different numbers and you can take your pick... what i like is that as long as you do it using this process you can make a change and it will tell you if the change is a pos or a neg. you can do the calculation every 500 rpm and get a curve...
for many, it is a simple way to decide just how much injector you need.
the best way is to look at a compressor map for your turbo and find the max pounds of air, then figure your AFR, do the math. don't forget to add in enough overhead so you are at 85% max duty cycle. also adjust volume from the gas numbers (above) to compensate for ethanol if it is a part of your base fuel.
this all bases off the relationship between raceports and airflow. peripheral ports and bridgeports have a different efficiencies. someone else will need to chime in as i don't do either.
fueling and rotary power are pretty easy IF you have the actual data.
actual data being exact flow of your injector at a particular pressure
actual digital fuel pressure
injectors (primary and secondary) duty cycle
fuel mix (adjust for BTUs per gallon)
AI pressure
AI injectant composition
accurate air fuel ratio
do the math and you end up w weight of the fuel per minute adjusted to gasoline at 6.3 pounds per gallon.
for instance, a well race ported rotary needs 80 pounds per minute of air to make 600 rw rotary hp.
if we decide to tune at 10.8 AFR it is pretty simple to calculate that we need 7.4 pounds of fuel.
7.4 X 10. 8 = 80
a gallon of fuel of gasoline weighs 6.3 pounds (weight varies slightly w temp) so 7.4/6.3 = 1.17 gallons per minute which is 4429 CC per minute.
4429 cc for 600.... if you want any other number just do the math.
2215 for 300.
i run around 1000 CC of meth as AI. i simply BTU adjust meth to gas and add it in. water is negative BTUs but if you are running 300/500 it isn't much of a factor..
once you solve for the weight of your fuel used it is easy to come up w hp and torque. i have been doing this for 20 years, have checked it on dynos and it is generally within 20 hp. this is dynojet hp SAE. obviously different dynos show different numbers and you can take your pick... what i like is that as long as you do it using this process you can make a change and it will tell you if the change is a pos or a neg. you can do the calculation every 500 rpm and get a curve...
for many, it is a simple way to decide just how much injector you need.
the best way is to look at a compressor map for your turbo and find the max pounds of air, then figure your AFR, do the math. don't forget to add in enough overhead so you are at 85% max duty cycle. also adjust volume from the gas numbers (above) to compensate for ethanol if it is a part of your base fuel.
this all bases off the relationship between raceports and airflow. peripheral ports and bridgeports have a different efficiencies. someone else will need to chime in as i don't do either.
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Senior Member
Joined: Jun 2010
Posts: 492
Likes: 246
From: Instagram - Copyninja_FD
"It might be worth having a chat with your tuner about what they'd recommend for a true 600 rwhp setup. You'll probably get a range of opinions, as injector sizing"
fueling and rotary power are pretty easy IF you have the actual data.
actual data being exact flow of your injector at a particular pressure
actual digital fuel pressure
injectors (primary and secondary) duty cycle
fuel mix (adjust for BTUs per gallon)
AI pressure
AI injectant composition
accurate air fuel ratio
do the math and you end up w weight of the fuel per minute adjusted to gasoline at 6.3 pounds per gallon.
for instance, a well race ported rotary needs 80 pounds per minute of air to make 600 rw rotary hp.
if we decide to tune at 10.8 AFR it is pretty simple to calculate that we need 7.4 pounds of fuel.
7.4 X 10. 8 = 80
a gallon of fuel of gasoline weighs 6.3 pounds (weight varies slightly w temp) so 7.4/6.3 = 1.17 gallons per minute which is 4429 CC per minute.
4429 cc for 600.... if you want any other number just do the math.
2215 for 300.
i run around 1000 CC of meth as AI. i simply BTU adjust meth to gas and add it in. water is negative BTUs but if you are running 300/500 it isn't much of a factor..
once you solve for the weight of your fuel used it is easy to come up w hp and torque. i have been doing this for 20 years, have checked it on dynos and it is generally within 20 hp. this is dynojet hp SAE. obviously different dynos show different numbers and you can take your pick... what i like is that as long as you do it using this process you can make a change and it will tell you if the change is a pos or a neg. you can do the calculation every 500 rpm and get a curve...
for many, it is a simple way to decide just how much injector you need.
the best way is to look at a compressor map for your turbo and find the max pounds of air, then figure your AFR, do the math. don't forget to add in enough overhead so you are at 85% max duty cycle. also adjust volume from the gas numbers (above) to compensate for ethanol if it is a part of your base fuel.
this all bases off the relationship between raceports and airflow. peripheral ports and bridgeports have a different efficiencies. someone else will need to chime in as i don't do either.
fueling and rotary power are pretty easy IF you have the actual data.
actual data being exact flow of your injector at a particular pressure
actual digital fuel pressure
injectors (primary and secondary) duty cycle
fuel mix (adjust for BTUs per gallon)
AI pressure
AI injectant composition
accurate air fuel ratio
do the math and you end up w weight of the fuel per minute adjusted to gasoline at 6.3 pounds per gallon.
for instance, a well race ported rotary needs 80 pounds per minute of air to make 600 rw rotary hp.
if we decide to tune at 10.8 AFR it is pretty simple to calculate that we need 7.4 pounds of fuel.
7.4 X 10. 8 = 80
a gallon of fuel of gasoline weighs 6.3 pounds (weight varies slightly w temp) so 7.4/6.3 = 1.17 gallons per minute which is 4429 CC per minute.
4429 cc for 600.... if you want any other number just do the math.
2215 for 300.
i run around 1000 CC of meth as AI. i simply BTU adjust meth to gas and add it in. water is negative BTUs but if you are running 300/500 it isn't much of a factor..
once you solve for the weight of your fuel used it is easy to come up w hp and torque. i have been doing this for 20 years, have checked it on dynos and it is generally within 20 hp. this is dynojet hp SAE. obviously different dynos show different numbers and you can take your pick... what i like is that as long as you do it using this process you can make a change and it will tell you if the change is a pos or a neg. you can do the calculation every 500 rpm and get a curve...
for many, it is a simple way to decide just how much injector you need.
the best way is to look at a compressor map for your turbo and find the max pounds of air, then figure your AFR, do the math. don't forget to add in enough overhead so you are at 85% max duty cycle. also adjust volume from the gas numbers (above) to compensate for ethanol if it is a part of your base fuel.
this all bases off the relationship between raceports and airflow. peripheral ports and bridgeports have a different efficiencies. someone else will need to chime in as i don't do either.
Which wmi kit do you use and how is yours setup?
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sstcabinboy
1st Generation Specific (1979-1985)
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Feb 22, 2008 09:00 PM
