Boy, this thread plays right into my current problem. I am trying to get a 5" inlet connected to my big turbo, but am having a time finding room between the alternator and the intercooler hard pipe. I may have to retreat back to 4", but I wonder if I will get enough CFM. The HT3B has a 5.5" OD inlet. Currently I am adapting down to 5", but have not had good luck the the 5" duct hose I was using. It collapses and gets sucked into the turbo. My air filter is an AFE with a 6" outlet, adapted down to 5". Since the HT3B can suck the hose into the turbo, I'm thinking maybe I don't have enough air, and if it will suck down this 5" hose, will it be worse with a 4" inlet.
Anyone have any ideas for figuring this out?

Thanks,
Chris

 

What type of hose are you using? Here is a link to a place I might purchase my airbox hoses from. Check out the silicone hoses and the tubing. They seem to have real good prices. Not sure if it will be of any assistance. If anyone has any better places, let me know.

http://racepartsolutions.com/index.htm

These guys have great stuff, just their prices are a little steeper.

http://www.burnsstainless.com/

 

I will check internal temps after I get it working. If it seems high, I can always throw some insulation on it. Besides, I have most of the stuff left over from other projects, so my costs will be way less than an aftermarket intake. If this one does not work, maybe I will make one out of stainless.

 

Thanks for the links. The first place doesn't seem to have anything for 5", but I will make a note of them for smaller stuff.

Thanks,
Chris

 

Boy do I feel dumb...

Major math mistake on my part.. DUHHH..

Thanks 600Mw... Geeze..


I wasn't going to try to calculate the oriface pressure drop as that changes with flow as you said. The basics I suppose is that a 4" flow pipe for the inlet should be ample for most single charger and most compound charger guys..

I guess I need more coffee..

 

There is a thread around somewhere where Scotty felt strongly about the 4.5" hole. Can't remember his reasoning...but i recall it was based on a lot of data.

There is JUST enough room to do a 4.5" hole. I suspect Scotty might have called for bigger, if there was room.

I drilled a 4.25" hole (all I had) and used a 1/2 round file (before I had a Dremel) to smooth the edges.....and open it up some. Ended with an bit of an oval with at least the recommended sq inches.

RJ

 

FYI-- all.

The 115 CFM figure is from David Vizard in an article about exhaust flow. He stated that you can calculate the flow of an exhaust system as being 115cfm per sq inch.

Thus, you can match the exhaust to the HP range of your engine. Important on an NA gasser, not so much on a turbodiesel.

I'm ASSuming that the 115 CFM is quoted at 28" WC, which seems fairly standard.

Then again, I think some carburetors are rated in CFM at only 10" WC, so WTH do I know

jlh

 

25" H20 was the standard for heads for umpteen years. Then some less than credible head manufactures conveniently started using 28" and not making that exactly clear in their advertisements. Thus their heads seemed to flow better.... Now you have 25" and 28" out there and you need to be cautious when comparing.


As for carbs, most of the time they are rated at 1.5" H.G. which is 20.4" H20.



KP

 

I went with the 4.5" for a few reasons.

1] it was the biggest I could go without chopping up the cowl too much.

2] I tried other sizes and the changes in the egt where noticable when using the truck for its purpose...towing heavy.

3] It was the best match to airflow from the reverse cowl positive air pressure I was seeking for trucks in the 300-450 HP range...anything over that would need a bigger turbo.

My original Psychotty I had just the cowl hole. I also netted or lost an additional 50F egt when I added the factory fender inlet.

INSERT SCOTTY SYSTEMS COMMERCIAL HERE...

Many years of R&D went into my air intakes. Its nice to know I have found a premium oiled foam filter with two layers and a product that not only reduces egt, it gives great oil anlaysis' and it also has been proven to extend the life of our engines by allowing us to tow easier and longer with the superior egt reductions compared to any others.

 

But, it is plastic. I ordered one from Diesel Dynamics a couple of years ago. I did not like the thin plastic construction, so I sent it back. I am sure it works great, but I just do not like the construction. I feels cheap. I know it really should not matter, as I will only see it when I pop the hood. The factory airbox even feels sturdier.

I am not knocking Scotty, as I have his fuel line kit on my wish list. He seems to be a great guy from reading his posts and reading what others have said about him. I just want something more substantial.

 

If you got one from DD it would've been stock from oh probably 1999 maybe 98. A lot has changed since then sir. I even offered to change them out from the Scotty I to the better...new style Scotty II. And they did feel cheap that is why I redesigned it. Its interesting how I never hear about these experiences off the boards.

You are comparing a product from many years ago that also had the poorly made K&N filter originally. K&N did not make an effort to improve their product, I have.

Have you seen my air intake in person lately?

Thanks for the report though.

Scotty

 

A-HA! Thanks, Kev.

As an aside, I knew that carbs were rated at a rather low pressure differential. That's why it's no big deal to have a carb that's too small. A 650cfm carb will work fine on a Big Block, and will flow 800cfm+ easy-- it will just have a restriction much higher than 1.5" HG

Thanks again, kev.

Wish I knew if Vizard is using 28" or 25" as a reference.

Justin

 

The current model of the SAII is made of material that I find just as rigid or better than the OEM box (if you want to use that as a standard).

 

Vizard is a legend in his own right. One of the few guys who actually backed up what did and didn't work with sound, solid, technical reasoning. He also was one to point out the applicability of stock parts over 'trick' aftermarket pieces that have less than 10% of the research the stock part they so proudly proclaimed they were superior to. He never sold out to the aftermarket. Probably why he was never as heavily in print as some of the other 'experts'.


David always used 25" H20 to flow heads. Exhaust system work, often falls under wildly varying test pressures though, and since the density is so much lower than air, rules of thumb regarding exhaust flow at a given pressure do not equate very well to airflow at the same pressure. I can't recall what test pressure he used on exhaust systems. I doubt it was very high, since you would need a ludicrously sized flowbench to pull 1,000's of CFM at 25". Same thing we all deal with on the carbs. Most flowbenches cant pull 750 CFM at 20.4", so we often test the carbs at much lower pressure and convert to 20.4". Its easy to do, airflow always follows the square law. As a matter of fact, my homebuilt 5 HP flowbench will only pull my quadrajets at 3" and when I convert to 20.4", guess what, dead on within a single CFM from what the 'big guys' get when they pull it with their SF-600's at 15" and convert to 20.4". As long as you have established fully developed flow, it scales dead nuts using the square law.

For my head work, I pull the full 25" up to about 200 CFM, then I have to drop the test pressure.

Anyway, sorry for the tangent... I have spent countless hours flowing heads, carbs and other stuff, and I enjoy the subject.



KP

 

Cool stuff 600MW...

Good information and it sounds like a cool test bench..