When did carbs Ever get rated Wet Flow CFM?

xctasy

xctasy

5K+
VIP
I've just got done on a live feed where a renown Physicist tutor with years of development work at Holley stated all Holley carbs are rated Wet Flow. And he told me that the always were rated Wet Flow, all ways Have Been, because they had wet testing 5500 CFM flow boxes. I'm a bit preplexed.. Based on what I've seen, this is categorically and historically wrong about airflow being measured wet. SAE J228 air flow was ratified in 1971. Before then, everything automotive in the US was for sure measured dry and still is today when flow benched on SF 600s,700s, 1020s etc.

I cited the 585 wet flow CFM for the 4180C Holley 4bbl is know to be 630 CFM dry. Quoted Ford Motor Company' 1983-1987 5.0 and 5.8 liter 4bbls from two sources.

The one size of large 4MA QuadraJet 4bbl is rated 725 CFM wet, and 800 CFM. Quoted from GM-Holdens HDT engineering assistant Larry Perkins in 1987.

Everything before 1971, everything was dry flow at a nominated 3.0, 2.0, 1.85 or 1.5 inches of Mercury Head pressure drop at an agreed average mean sea level, humidity and temperature.

Anyone Agree/Disagree.

Thoughts?
 
Last edited:
I had heard about wet flow testing many years ago, understanding at the time it was done by automakers and a few major manufactures; but dismissed it as something way above my head. I haven't heard since about it until you bring it to point. Is this why some carburetors are sold as 525cfm or other odd cfm rating?
 
Yes, Wet Flow Testing was always a thing done at the carburettor or Throttle Body injection design phase, but not wet flow rating until sometime in the Barry Grant era, and then with Demon carbs.

Or so the Australians had me believe.

The Carter CFM ratings, dry, but not supplied by ACF Carter, they we tested by another company
Autolite ratings, dry.
After the anti trust break-up of Autolite, Motorcraft became a thing in 1971, and all those Buy in 5760 Carter Weber, 52xx/62xx Holley Weber and 1945/1946/2380/ 4180/4185/4195 Holley carbs, either wet flow, or at a reduced Hg head.

So I'm sure the Dry and Wet change started happening in or from 1971, like having a Net and Gross Hp rating the same time.

I just haven't ever seen Holley 1, 2 or 3 or 4bbls rated at Wet flow. When EconoMaster and Annular Boosters came in from 1973 to 1988, the air flow rating changed some, but I thought the basic carbs were all dry rated, except for the revised European Carter Webers and Holley Webers.
 
Last edited:
Is wet flow testing done with a controlled amount of moisture? Certainly, changing the density
It must improve the accuracy of how much flow you're actually going to be use; like you stated, net compared to gross.
Reflecting on back when, Mack trucks would rate their engine (their own btw) at say 235, it was to the ground; while the other truck manufactures would call it a 350 (cummins). Bigger numbers always seem to command a higher price tag
 
xctasy said:
I cited the 585 wet flow CFM for the 4180C Holley 4bbl is know to be 630 CFM dry. Quoted Ford Motor Company' 1983-1987 5.0 and 5.8 liter 4bbls from two sources.

Thoughts?
Click to expand...
That is correct. I was the dynamometer development engineer on the 5.0 HO program. I believe the carb blueprint shows both the dry and wet flow numbers. (I'm not where I can check that.) For the ad campaign and magazine reviews the numbers generally tossed out were the dry numbers, presumably just to be consistent with the rest of the industry.
sixtseventwo4d said:
Is wet flow testing done with a controlled amount of moisture? Certainly, changing the density
It must improve the accuracy of how much flow you're actually going to be use; like you stated, net compared to gross.
Click to expand...
Wet testing is done under controlled laboratory conditions to insure consistency - constant barometric pressure in a hyperbaric chamber, constant humidity and temperature - using a non volatile non-flammable fluid with similar flow characteristics as gasoline. It was called "Stoddard". I don't know if that was a trade name or a generic formulation. Kinda like the word Kleenex.
It gets complicated. You have to have a way to recover the Stoddard from the airstream so you are not continually releasing that blended mixture into the laboratory or atmosphere. I never saw the recovery process or that equipment so it was all magic to me.

When EFI became the norm those test chambers were converted to fuel injector test stands.
 
I have used a Wet Flow Bench during my Aircraft Engine Lic. training (in 1967 - 1968) I think that at least in that time frame that was the only way they flow rated those Carb's in the Aircraft Industry. But I had also heard that the Carter AFB's were one of the only Carbs that used the Wet Flow ratings for their Carb's in their advertising.
 
Thankyou people. Prior to 1971, when wet flow testing was done, the fluid was benzene. The recovery vat was flame arrested, and because aromatic hydrocarbons of that molecular weight are both carcenigenic and a depressant according to my Material Safety Data Sheets, a new safe , non flamable fluid with the same 0.72-0.76 specific gravity as gasoline and thus the same flow rate was used from 1971 onwards.

Here is the discussion, Mark Campbell, interviewed by Drag Boss.
Join the channel, and you Won't Ever be disappointed. Let everyone judge the valuable live feed for themselves. I had some issues with what he said, but I guess that's just me. It was one the many Best Choices Drag Boss makes on his Ford Cleveland V8 channel. Thankyou Mark Campbell. 🎷

 
Last edited:
Well, got a reply from Mark C. He basically affirmed that all carb airflow in the USA is done wet. News to me

Here is my response

@ Mark Campbell Thankyou Mark. I respect what you've said. I've worked 11 years in three Materials Testing laboratories between 1992 and 2020, doing a broad mixture of petro-chemical, propane, and nuclear and destructive and nondestructive materials testing within the ASTM and CBIP standards. I'm now okay with what you've said, I certainly wasn't on the channel feed when you said that same thing. That was quite a shocker for me. All my historical US supplied carb data has therefore been from a mix of sources. I was told something different with respect to Carb Specifications, and modeld my gas flow figures without the gasoline, alcohol and propane fuel displacement flow figures. Oh, and I've worked with Benzene too. Thanks again.
 
bubba22349 said:
I have used a Wet Flow Bench during my Aircraft Engine Lic. training (in 1967 - 196:cool: I think that at least in that time frame that was the only way they flow rated those Carb's in the Aircraft Industry. But I had also heard that the Carter AFB's were one of the only Carbs that used the Wet Flow ratings for their Carb's in their advertising.
Click to expand...
Doug Roe & Bill Fisher's priceless publication indicates that Rochester also wet-flowed all carbs. (If you want to super-tune a Rochester, this is the book to have.) 100_0629.JPG100_0630 (2).JPG
 
You must log in or register to reply here.
Back
Top