60 lb injector swap on Radix 2004
05-10-2005, 09:17 PM
#63
TECH Veteran
they may be good for that much power naturally asperated, but remember that when you are pushing into a boosted area a 42 isn't really a 42 either. this is the main reason a diesel runs so high of a fuel pressure aside from trying to get better atomization. they have to overcome the cylinder pressure of the cylinder on compression stroke with extreme amounts of fuel pressure. i'm not sure what the formula is, but forcing a presssurized anything into a pressurized area will slow down the flow. forcing the same thing (fuel in this case) into an area that is at atmospheric pressure or a low pressure area (what we know as vacuuum) will increase it's flow ability. this is kinda like filling a tire. filling a tire with zero pressure to ten psi with say 60psi in your tank is considerably easier than filling that same tire from 20psi to 30psi using 60psi in the tank. this is why you can run say a 30lbhr injector with a 5.7 running a t-rex cam making 450rwhp and the same engine on boost only making 450rwhp takes much more injector. pretty much the higher the boost level the more injector size you'll need also.
btw, i still would like to than you again richard. your information at the point we were at was considerable help. much appreciated and i owe you one.
btw, i still would like to than you again richard. your information at the point we were at was considerable help. much appreciated and i owe you one.
05-10-2005, 10:41 PM
#65
Originally Posted by zippy
they may be good for that much power naturally asperated, but remember that when you are pushing into a boosted area a 42 isn't really a 42 either. this is the main reason a diesel runs so high of a fuel pressure aside from trying to get better atomization. they have to overcome the cylinder pressure of the cylinder on compression stroke with extreme amounts of fuel pressure. i'm not sure what the formula is, but forcing a presssurized anything into a pressurized area will slow down the flow. forcing the same thing (fuel in this case) into an area that is at atmospheric pressure or a low pressure area (what we know as vacuuum) will increase it's flow ability. this is kinda like filling a tire. filling a tire with zero pressure to ten psi with say 60psi in your tank is considerably easier than filling that same tire from 20psi to 30psi using 60psi in the tank. this is why you can run say a 30lbhr injector with a 5.7 running a t-rex cam making 450rwhp and the same engine on boost only making 450rwhp takes much more injector. pretty much the higher the boost level the more injector size you'll need also.
btw, i still would like to than you again richard. your information at the point we were at was considerable help. much appreciated and i owe you one.
btw, i still would like to than you again richard. your information at the point we were at was considerable help. much appreciated and i owe you one.
i think you are missing something.
the injector will flow the exact same amount of fuel if the fuel presure is boost regulated like on my 03, that is the reason they put the regulator on there. it will flow less on an 04 since they have a constant fuel presure and the boost will be fighting the fuel coming out.
typicaly the reason you need more injector on a boosted car is because most people run boosted cars at a richer a/f ratio. it has nothing to do with boost fighting the fuel presure since most people run a boost refrenced fuel presure regulator.
05-10-2005, 10:48 PM
#66
TECH Veteran
i was referring to something running the same pressure such as the 04'. it was directed at the comment about the hp levels and injector size for an 04' above. i agree with you about running the boost referrenced fuel pressure regulator. my comment was only about the difference in an 04' N/A and 04' Boosted.
05-11-2005, 12:08 AM
#67
You are very welcome Zippy. This stuff is pretty fun. I'm glad I could get you headed in the right direction.
Here is a post I made on the SS site to explain the difference in fueling between vehicles. Sounds like it would be beneficial here too:
A little more in depth answer:
Our reference for measuring pressure is the earths atmosphere. 58psi is our default fuel pressure, but thats in reference to external atmospheric pressure. At idle, our vehicles build up vacuum pressure in the manifold. Our PCM calculates its fueling based off the amount of fuel an injector can flow over a given time. At idle, the injector is under vacuum pressure from the manifold on one side and has fuel pressure pushing from the other side. That vacuum basically increases flow by sucking fuel out when the injector is open. This is common to both truck setups.
On the 99-03 models, the fuel rail has a pressure regulator that bleeds off excess fuel to keep pressure at 58psi at one atmospheric pressure. It has an internal mechanism that connects to the intake manifold which allows a lower fuel pressure when under vacuum at idle. That lower pressure is in direct relation to the added fuel flow gained from being under vacuum. Basically that means that even though the injector is getting increased flow from vacuum pressure, its also getting lower fuel pressure (and less flow) from the regulator. This should equal out for a constant fuel injector flow rate. When the throttle is opened up, the manifold isn't under vacuum and the regulator increases fuel pressure back to 58psi.
On the 04+ models, the regulator isn't hooked up to the intake manifold, so it doesn't see any vacuum (or boost). That means its always flowing a consistent 58psi. To compensate for the added injector fuel flow when under vacuum, the PCM is told it has larger injectors for different levels of manifold pressure. Relying on the MAP sensor, the pcm knows how much vacuum the truck has at idle. It uses that value to adjust the injector flow rate in fuel calculations. This allows the proper amount of injector fuel under vacuum or WOT. The end result is consistent fueling.
The 99-03 way is a manual workaound for vacuum increased fuel flow rate and the 04+ way is an electronic calculated workaround. Both ways work fine. But when adding forced induction to the mix, the 99-03 fuel pressure regulator acutally raises pressure above 58psi allowing more fuel flow. The 04+ system cannot compensate in this way, and if it did, it would just calculate it in as a small injector. So it would be more likely for a 04+ truck to run out of injectors than an 03 under boost.
Here is a post I made on the SS site to explain the difference in fueling between vehicles. Sounds like it would be beneficial here too:
A little more in depth answer:
Our reference for measuring pressure is the earths atmosphere. 58psi is our default fuel pressure, but thats in reference to external atmospheric pressure. At idle, our vehicles build up vacuum pressure in the manifold. Our PCM calculates its fueling based off the amount of fuel an injector can flow over a given time. At idle, the injector is under vacuum pressure from the manifold on one side and has fuel pressure pushing from the other side. That vacuum basically increases flow by sucking fuel out when the injector is open. This is common to both truck setups.
On the 99-03 models, the fuel rail has a pressure regulator that bleeds off excess fuel to keep pressure at 58psi at one atmospheric pressure. It has an internal mechanism that connects to the intake manifold which allows a lower fuel pressure when under vacuum at idle. That lower pressure is in direct relation to the added fuel flow gained from being under vacuum. Basically that means that even though the injector is getting increased flow from vacuum pressure, its also getting lower fuel pressure (and less flow) from the regulator. This should equal out for a constant fuel injector flow rate. When the throttle is opened up, the manifold isn't under vacuum and the regulator increases fuel pressure back to 58psi.
On the 04+ models, the regulator isn't hooked up to the intake manifold, so it doesn't see any vacuum (or boost). That means its always flowing a consistent 58psi. To compensate for the added injector fuel flow when under vacuum, the PCM is told it has larger injectors for different levels of manifold pressure. Relying on the MAP sensor, the pcm knows how much vacuum the truck has at idle. It uses that value to adjust the injector flow rate in fuel calculations. This allows the proper amount of injector fuel under vacuum or WOT. The end result is consistent fueling.
The 99-03 way is a manual workaound for vacuum increased fuel flow rate and the 04+ way is an electronic calculated workaround. Both ways work fine. But when adding forced induction to the mix, the 99-03 fuel pressure regulator acutally raises pressure above 58psi allowing more fuel flow. The 04+ system cannot compensate in this way, and if it did, it would just calculate it in as a small injector. So it would be more likely for a 04+ truck to run out of injectors than an 03 under boost.
05-11-2005, 12:17 AM
#68
All you HPTuner guys, do you know if the 2 or 3 bar operating system support will extend fuel injector flow rate table to include both vacuum and boost? As it is now, the 2004+ trucks have different calues for injector flow rate depending on vacuum, with the last cell being 0 vacuum. It seems they would also need to have values beyond vacuum into boost to continue properly fueling the vehicle.
05-11-2005, 10:45 AM
#69
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Originally Posted by BigTex
All you HPTuner guys, do you know if the 2 or 3 bar operating system support will extend fuel injector flow rate table to include both vacuum and boost? As it is now, the 2004+ trucks have different calues for injector flow rate depending on vacuum, with the last cell being 0 vacuum. It seems they would also need to have values beyond vacuum into boost to continue properly fueling the vehicle.
No clue on the 2 bar system. I thought about perhaps converting briefly, but since we've got the truck running fine on the stock system and I'll never make more than 8-9 psi I'll stay on the stock. I think as long a people stay at lower boost levels, meaning 10 or less (just a guess with the 10), that they can use the method that Magnuson used of a constant injector flow rate in the IFR tables combined with MAFless VE tuning and some MAF scaling.
I'll bet that if the 2 bar system does extend the IFR table it would be easier to work a supercharged tune up from a stock tune. When we experimented with a Magnuson tune base using a stock type IFR scaling for the addition of the motron 60's things got a little wacked and very inconsistent. It was much easier to use the constant IFR.
