Question about turbo's and low RPM's.
01-22-2005, 04:06 PM
#1
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Question about turbo's and low RPM's.
ok something just jogged my thought (i think it was aliates post on the NA then turbo motor). if a car is running at low RPM and is running off vacuum how can the huge injectors meant for gobs of air run on such a low duty cycle?
ive heard of turbo stangs making 500 RWHP and needing the 50lb injectors, what happens when this car is idling? how can those huge injectors accurately meter tiny amounts of fuel? (for the injectors relatively speaking)
because i know you cant run a 300 HP NA motor on 50 lb injectors unless you are running nitrous up the ***.
after all, a turbo motor at 2500 RPM is not making much more power than a 300 HP motor at 2500 RPM. so how can the injectors cope with this?
ive heard of turbo stangs making 500 RWHP and needing the 50lb injectors, what happens when this car is idling? how can those huge injectors accurately meter tiny amounts of fuel? (for the injectors relatively speaking)
because i know you cant run a 300 HP NA motor on 50 lb injectors unless you are running nitrous up the ***.
after all, a turbo motor at 2500 RPM is not making much more power than a 300 HP motor at 2500 RPM. so how can the injectors cope with this?
01-22-2005, 05:22 PM
#2
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RE: Question about turbo's and low RPM's.
My guess is that's it all handled in the programming of the ECU and probably includes a boost controller of some sort on the fuel pressure regulator which can lower the fuel pressure at low or zero boost levels but still be able to increase the fuel pressure as the boost comes on at higher rpms. I also vaguely remember reading something about variable speed fuel pumps being used in boosted applications too. you might try asking these questions in the pipes and boost section also, you would probably get better response there.
01-22-2005, 05:23 PM
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RE: Question about turbo's and low RPM's.
ORIGINAL: roundman
My guess is that's it all handled in the programming of the ECU and probably includes a boost controller of some sort on the fuel pressure regulator which can lower the fuel pressure at low or zero boost levels but still be able to increase the fuel pressure as the boost comes on at higher rpms. I also vaguely remember reading something about variable speed fuel pumps being used in boosted applications too. you might try asking these questions in the pipes and boost section also, you would probably get better response there.
My guess is that's it all handled in the programming of the ECU and probably includes a boost controller of some sort on the fuel pressure regulator which can lower the fuel pressure at low or zero boost levels but still be able to increase the fuel pressure as the boost comes on at higher rpms. I also vaguely remember reading something about variable speed fuel pumps being used in boosted applications too. you might try asking these questions in the pipes and boost section also, you would probably get better response there.
do people even respond to posts in those sections? rofl
01-22-2005, 07:24 PM
#4
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RE: Question about turbo's and low RPM's.
lots of people run a piggy back system for the ECM and lean the motor out at lower rpms and at idle.and they run a sensor for the boost and the piggy back knows when the motor comes up on boost.or they run a FMU and a smaller injector and when it comes up on boost it closes off the return line on the fuel and spikes the press. way up and makes the little inj. think it is big but you have to have a big pump cuz when you raise press. the pumps supply ability goes down due to the press. they can also be hard to tune as they tend to be very fat down low and lean on top. but a inj. can reach a limit on how much power it can make as you know no matter how much press. you put to it.
01-22-2005, 07:26 PM
#5
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RE: Question about turbo's and low RPM's.
ORIGINAL: Dbeck002
ok something just jogged my thought (i think it was aliates post on the NA then turbo motor). if a car is running at low RPM and is running off vacuum how can the huge injectors meant for gobs of air run on such a low duty cycle?
ive heard of turbo stangs making 500 RWHP and needing the 50lb injectors, what happens when this car is idling? how can those huge injectors accurately meter tiny amounts of fuel? (for the injectors relatively speaking)
because i know you cant run a 300 HP NA motor on 50 lb injectors unless you are running nitrous up the ***.
after all, a turbo motor at 2500 RPM is not making much more power than a 300 HP motor at 2500 RPM. so how can the injectors cope with this?
ok something just jogged my thought (i think it was aliates post on the NA then turbo motor). if a car is running at low RPM and is running off vacuum how can the huge injectors meant for gobs of air run on such a low duty cycle?
ive heard of turbo stangs making 500 RWHP and needing the 50lb injectors, what happens when this car is idling? how can those huge injectors accurately meter tiny amounts of fuel? (for the injectors relatively speaking)
because i know you cant run a 300 HP NA motor on 50 lb injectors unless you are running nitrous up the ***.
after all, a turbo motor at 2500 RPM is not making much more power than a 300 HP motor at 2500 RPM. so how can the injectors cope with this?
01-22-2005, 08:13 PM
#6
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RE: Question about turbo's and low RPM's.
yea thats kinda like what i meant, when cruising at low RPM how can the injectors handle such a low output of fuel accurately. i think its like trying to hit bb with a baseball bat, kinda hard to do that accurately.
01-22-2005, 11:11 PM
#8
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RE: Question about turbo's and low RPM's.
well first you want the right turbo for your app. then use a pms to adjust timing and injector pulses.etc so larger injectors can be use...injectors 42# or larger a chip or the like is needed for a good idle and to wart off low end stumble.. when using a turbo it's good to have 2 pumps..which I use on my s/c so if 1 pump fails it doesn't lean out and let the engine go south..so a 190-225 pump and a 75# inline work great.....also pump pressure can be used by vacuum to be trailored to the engine needs
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