intake horns, efficiency, cfm......blah blah

[foolkiller]

this is in redirect of a couple threads discussing intake horns and the questions i'm getting.



i've used a bunch of math that i haven't used since about 1980 when i was trying to master the small block chevy. i'll avoid listing a bunch of math unless someone wants to read it.



keeping it short.



being generous i gave our trucks 180% volumetric efficiency (they're well below that by my math), RPM at 3000, and used 30lbs of boost as a high average to err on the side of caution. (basically skew the numbers to force the need for improved intake flow... ... . i think i failed)



unless i'm more rusty than i thought, i came up with 561cfm as the high end of what our trucks will flow on the intake side under realistically high demand and regardless of the CFM of the various intake horns.



our stock horn will flow that, not much more, but it will.



if this is the case, am i correct in concluding that after market intake horns are really only helping with a little heat displacement?



i've been getting a lot of questions about my horn and don't want to misguide anyone. so far all i've commited to is that they're all better than stock and to pick the one that fits for desired future upgrades. but i'd like to tell em how they help.



jeff

 

[Bob4x4]

To start with you need to understand a naturally aspirated engine is different than forced air induction. The stock manifold can flow more air than the 5,9 will ever need,but at what restriction?



AFE uses an industry accepted standard of 1. 5" of water for their flow test,CFM uses something different(they would never answer my question as to what that # might be).



As the restriction rises the boost needed to supply that quantity also rises.



With my AFE flow products I can cruise at 65 pulling the trailer at 7-8 lbs of boost at about 700 degrees.

Stock products my boost #s and egts were higher.



Bob

 

[drury]

I forget the math, but I would think that higher boost lessens the flow demand. At lower boost the restriction matters more. If that's the case, then a lower restriction horn will help a lot during the early phases of acceleration before the turbo is spooled up. It would also help during Bob's scenario of a steady 7-8 pounds of boost.



My goal for my truck is to try to get as much air as possible into the engine under low boost conditions so that I can drive with the power turned up all the time without putting out a black cloud of smoke every time I step on the throttle. That's why I've upgraded almost every single part that touches the airflow stream. So far it's been pretty successful. Hopefully I'll get to test out the head port next week.

 

[foolkiller]

i understand the difference between the naturally aspirated and charge air. i accounted for atmospheric pressure. i understand restriction too but restriction was something i didn't know how to add in... ... . assume no restricion, the cfm is still low.



actually i erred on the side of best case scenario for everything i could to try to justify the need for more cfm and still came in with right around 600cfm. (no restriction, 200% VE)



as for the EGTs and how hard the turbo has to work to get XXlbs of boost through a hole (restriction) and how it effects heated air, i can handle explaining that. but the truck still only needs XXXcfm.



i guess my question is, basically if i got the 560cfm correct (or at least realistic) and are we just buying a little cooler air? not that cooler air doesn't justify the cash.



when i posted my intake install (and blabbed at work) i got some questions and i don't want my answers to be compete BS, partial is ok, but not all of it.



i was avoiding brand names if possible. and i think i've tired my self of the topic anyway. trying to remember the formulas and how to work em was a challenge after so long not thinking of them.



jeff

 

[foolkiller]

smoke is something i did not consider at all..... good point

 

[p-Bar]

Foolkiller I read about 550 cfm somewhere can't remember where.

 

[DCreed]

believe it or not ,the factory DOES have engineers that figure this stuff out for stock. It's usually the power hungry consumer who will push the limits and is willing to trade some aspects of drivablity for performance gains. So with 3 times the fuel and 60+ lbs of boost the stock parts start to get a wee inadequate. If the intake horn smooths flow and increases it to 1000cfm thats great, but if your still stock its just bling, and may even hurt response(extreme example) like dual quads on a commuter car.

 

[Bob4x4]

Foolkiller I read about 550 cfm somewhere can't remember where.

There comparison in the adds iswhat I would guess... ... ... ... when I asked the owner of CFM at what restriction he would not reply

AFE did test it along with the other competitors... ... ..... all at the same test parameters.

With enough boost you can push 3000cfm through any of them including stock.



Bob

 

[p-Bar]

There comparison in the adds iswhat I would guess... ... ... ... when I asked the owner of CFM at what restriction he would not reply
AFE did test it along with the other competitors... ... ..... all at the same test parameters.
With enough boost you can push 3000cfm through any of them including stock.

Bob

I think 28 inches water is the correct number for flowing heads and intakes excluding airfilters

Wonder why AFE doesn't post the the test results?

This things just another heat sink something I thought we are trying to not do ,reducing air density

I think CFM+ did the right thing by thinking outside the box and using the high temp engineered composite materials.

Further more CFM+ didn't farm it out to CHINA ,made in the USA by Americans for Detroit IRON

 

[WoodChuck]

Just put the CFM + on mine and I think it drop my EGT's about 100 degrees.
Before with my Hot Juice on max my EGT's went over 1350 pretty quick on WOT. Now It takes a lot longer to get up there and when it does it only backs down a little bit, EGT's drop quickly and it's back to 100% power.
I'm very pleased with the results. Anybody looking for max power and efficiency should upgrade their air horn.

 

[Stefan Kondolay]

Hey Bob,



How do you think the intake horns on the market would compare to the one that I built 5 years back. I built a new base plate, the long one under the lines, out of billet made a round hole, instead of the squared off ends. Used a o-ring to seal it. then built a heater grid replacement that was also round, then the intake horn was round thru-out so that everything had a constant flow. What I did to make everything look clean was had the base under the lines drilled and tapped for the boost gauge and nitrous, so everything looked clean.

 

[DCreed]

Hey Bob,



How do you think the intake horns on the market would compare to the one that I built 5 years back. I built a new base plate, the long one under the lines, out of billet made a round hole, instead of the squared off ends. Used a o-ring to seal it. then built a heater grid replacement that was also round, then the intake horn was round thru-out so that everything had a constant flow. What I did to make everything look clean was had the base under the lines drilled and tapped for the boost gauge and nitrous, so everything looked clean.

PICS, PICS, PICS !!!

 

[Gary - K7GLD]

Along the lines of this thread topic. this generated a lot of interest - and heat - when it was posted:



https://www.turbodieselregister.com.../136388-value-special-aircleaner-ducting.html

 

[Bob4x4]

Hey Bob,



How do you think the intake horns on the market would compare to the one that I built 5 years back. I built a new base plate, the long one under the lines, out of billet made a round hole, instead of the squared off ends. Used a o-ring to seal it. then built a heater grid replacement that was also round, then the intake horn was round thru-out so that everything had a constant flow. What I did to make everything look clean was had the base under the lines drilled and tapped for the boost gauge and nitrous, so everything looked clean.

Sounds like a good idea,What we are seeing now I think the restriction is the size of the flange. It would be interesting to flow yours to see where it comes in at. AFE had considered starting with a new base plate as well but you have to keep the price point in mind when designing for the retail market.



Hvac made a round tube intake for his Red Rocket but stayed with the stock flange. He had admitted to me he wasn't sure if he got any real world gain,but @ 600hp it's tough to feel small gains.



Bob

 

[DCreed]

would like to know if any gains for a modded base plate as it seems a narrow passage and hard bend. I'm going to smooth all passages while truck is down for VP.

 

[Stefan Kondolay]

Bob, I haven't really look at what other kits cost but I don't see why you couldn't get a base plate, heater grid eliminator and the horn for under $400. I don't know what guys are will to pay though. I thought it would look sweet if the horn was polished stainless, I bet that wouldn't add to much to the cost.



The smooth flow just makes more sense to me, than keeping the square base then turning it to round on the other side.

 

[ThrottleJockey]

Uhhh, Stefan...



You live in Canada.



Why on Earth would you want a grid heater eliminator?



These look pretty neat: https://www.turbodieselregister.com...um-1989-1993/191199-coolertubz-installed.html

 

[Bob4x4]

Bob, I haven't really look at what other kits cost but I don't see why you couldn't get a base plate, heater grid eliminator and the horn for under $400. I don't know what guys are will to pay though. I thought it would look sweet if the horn was polished stainless, I bet that wouldn't add to much to the cost.



The smooth flow just makes more sense to me, than keeping the square base then turning it to round on the other side.

Stepfan,

Maybe this winter you will have a new project to play with ?

On the old 94 I did the Chrome and make it look as good as it runs thing,but on the 05 I am having way too much fun with making it handle off road and just run like it should. Just got back from the Baja 1k where the Dodge strutted it's stuff with out any thing shiny under the hood :-laf



Bob