Fuel Vs. Air
01-01-2017, 10:53 AM
#16
Banned
01-01-2017, 11:01 AM
#17
Registered User
Thread Starter
5% gain in VE isn't just for head porting. VE rises with the more air you cram in, (or at least that's how I read it on many sites, the performance section of the Garrett site being the main one I've read). Since none of us are going to pay the money to have our poor flowing heads flowed on a bench the 5% was just a general for rise in boost. If you read some places assume close to 92%VE which would probably be a good assumption for a new style diesel engine but I doubt any of us would reach that much efficacy.
01-01-2017, 04:51 PM
#18
Registered User
Thread Starter
agreed. but since i know the stock injectors are ~40LPM air, we'll use air for this theoretical comparison.
if we use 18psi as our baseline boost number, because thats what most stock trucks will give you. heres what we come up with
[(18psi+14.7) / 14.7] x 5.9L = ~800 c.i.
so we can say that stock 40 LPM injectors will fuel the stock 800 c.i.
now for your massive air pump
[(55psi+14.7) / 14.7] x 5.9L = ~1707 ci.
thats 2.13x the cubes
so 40 LPM x 2.13 = 85.2
so i could theoretically say that as long as fuel supply is there, meaning you don't suck your A1000 lift pump and Giles IP dry, 85 LPM injectors would fuel your 1707 CI.
as previously stated, this is by no means a scientific way of determining injector size. just a fun, theoretical convo.
if we use 18psi as our baseline boost number, because thats what most stock trucks will give you. heres what we come up with
[(18psi+14.7) / 14.7] x 5.9L = ~800 c.i.
so we can say that stock 40 LPM injectors will fuel the stock 800 c.i.
now for your massive air pump
[(55psi+14.7) / 14.7] x 5.9L = ~1707 ci.
thats 2.13x the cubes
so 40 LPM x 2.13 = 85.2
so i could theoretically say that as long as fuel supply is there, meaning you don't suck your A1000 lift pump and Giles IP dry, 85 LPM injectors would fuel your 1707 CI.
as previously stated, this is by no means a scientific way of determining injector size. just a fun, theoretical convo.
Why did you add an atmosphere to the boost #? Not saying its wrong but I don't understand, shouldn't we assume the 360 already has the atmosphere in it? I could be very wrong here but how I was trying to figure it using your example is; 18/14.7=1.22. 1.22X360=440ci. Factor in our VE of .7 our 440=308 CI.
I'll also note I'm hoping my A1K can keep the pump feed. It's a big **** lift pump. AN10 lines are freaking huge too!!!
01-01-2017, 04:55 PM
#19
Banned
In my example, I didn't have to multiply by .7 for VE because it was already factored in by the fact we were using a stock 65% VE to begin with. I did correct myself and factored in the +5% VE as per your s.w.a.g.
01-01-2017, 04:57 PM
#20
Banned
And I "added" the atmosphere to the equation because that's the equation. I didn't write it, I just plugged in our numbers. Mathing
1 psi is 1 psi above atmospheric pressure(14.7)
Therefore 1 + 14.7 = 1 psi of boost.
1 psi is 1 psi above atmospheric pressure(14.7)
Therefore 1 + 14.7 = 1 psi of boost.
01-01-2017, 07:10 PM
#21
Banned
agreed. but since i know the stock injectors are ~40LPM air, we'll use air for this theoretical comparison.
if we use 18psi as our baseline boost number, because thats what most stock trucks will give you. heres what we come up with
[(18psi+14.7) / 14.7] x 5.9L = ~800 c.i.
so we can say that stock 40 LPM injectors will fuel the stock 800 c.i.
now for your massive air pump
[(55psi+14.7) / 14.7] x 5.9L = ~1707 ci.
thats 2.13x the cubes
so 40 LPM x 2.13 = 85.2
so i could theoretically say that as long as fuel supply is there, meaning you don't suck your A1000 lift pump and Giles IP dry, 85 LPM injectors would fuel your 1707 CI.
as previously stated, this is by no means a scientific way of determining injector size. just a fun, theoretical convo.
if we use 18psi as our baseline boost number, because thats what most stock trucks will give you. heres what we come up with
[(18psi+14.7) / 14.7] x 5.9L = ~800 c.i.
so we can say that stock 40 LPM injectors will fuel the stock 800 c.i.
now for your massive air pump
[(55psi+14.7) / 14.7] x 5.9L = ~1707 ci.
thats 2.13x the cubes
so 40 LPM x 2.13 = 85.2
so i could theoretically say that as long as fuel supply is there, meaning you don't suck your A1000 lift pump and Giles IP dry, 85 LPM injectors would fuel your 1707 CI.
as previously stated, this is by no means a scientific way of determining injector size. just a fun, theoretical convo.
[(18psi+14.7) / 14.7] x 5.9L = 800 c.i.
800 ci x .65 = 520 ci.
so we can say that stock 40 LPM injectors will fuel the stock 520 c.i.
now for your massive air pump
[(55psi+14.7) / 14.7] x 5.9L = 1707 ci.
1707 x .70 = 1195 ci
so thats 2.3x the cubes from stock
so 40 LPM x 2.3 = 92 LPM
01-18-2017, 08:17 AM
#22
Banned
bringing this one back from the dead as i'm feeling nerdy this morning.
so been doing some CFM calculations. we'll use your 1195 ci motor, 55 psi, 2500 rpm as our test bed.
(1195ci x 2500rpm x 0.5 x 0.70)/1728 = 605 cfm air demand.
so been doing some CFM calculations. we'll use your 1195 ci motor, 55 psi, 2500 rpm as our test bed.
(1195ci x 2500rpm x 0.5 x 0.70)/1728 = 605 cfm air demand.
01-18-2017, 01:22 PM
#23
Banned
and now to throw a total wrench into the mix is increased VE due to boost. so i found a "standard" equation to convert from NA VE to boosted VE.
so if 65% VE NA our little tractor motor would be at 165% VE @ 55 psi.
this is where head work really impacts power. increasing the VE through cylinder head porting. was talking with Mark Wilson at dieseltuff about boost and how we often look at it as power. it's really just a measure of restriction. better flow, less restriction, more efficient. think same power/flow/VE at lower boost.
so if 65% VE NA our little tractor motor would be at 165% VE @ 55 psi.
this is where head work really impacts power. increasing the VE through cylinder head porting. was talking with Mark Wilson at dieseltuff about boost and how we often look at it as power. it's really just a measure of restriction. better flow, less restriction, more efficient. think same power/flow/VE at lower boost.
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mknittle (01-21-2017)
01-21-2017, 07:26 PM
#25
Registered User
Think of it as an air pump the better the flow the easier to make power. same as a hotrod gasser.
The way I see it, projected horsepower is the way to size everything, whether you're 359cid or 1100cid.
01-25-2017, 05:34 AM
#27
Banned
I'll just be over here in my corner with my holset turbo and Ve pump, hahaha.
02-05-2017, 05:59 PM
#28
Registered User
Thread Starter
Like to see this got a bit of traction. Let's bump this up and see if anyone else has some input, I really don't know if there's a wrong answer. Gents and ladies this is how we come to conclusions, don't be scared of posting!