[Keith Seymore]

Just as an aside: this was my first design/release assignment for GM -

I did the engine air induction system for the 1999 and beyond "GMT800" trucks. One airbox (with a LD or optional HD filter element) and ductwork to accommodate 7 different powertrain combinations. Air temperature rise and flow restriction from ambient air inlet to the throttle body were tightly controlled.

Many of the parts are still in use today, over 20 years later.

K

[Jay S]

That was a pretty impressive first design release.

I think people may miss that when you drop the air temp the mass flow rate is increased for the same air pressure. They were indeed ramming more air into the engine, but not by pressure, it was by air mass.

Just to compare, I added the ram air photo to compare to that GM design Keith did. The modern air cleaner ducting doesn’t have multiple places that the air is drawn in from. The cold air intakes that are most effective either eliminate the places where hot air is coming in and mixed with the cooler air, or have a scoop that has a big enough pressure differential that at speed there is less hot air in the mix, but oem still had to keep the benefits of the heat risers and cold weather attributes needed with a carb.

[BB70]

Made my cowl hood functional last spring when I had free time #¥×π^.Definetly was worth it.

[Jay S]

Nice looking cowl set up.

Probably should have mentioned that photo of the RA 4 induction a couple posts up was a prototype with big air ducts coming from the front end was never put in production. Probably because they tested it on stuff like this:

Lol

[Tom Vaught]

YEP, WATER INGESTION is one of the key requirements you MUST pass prior to actual production.
I am sure that Mr Seymore's induction design passed with flying colors.

Tom V.

[Keith Seymore]

Originally Posted by Tom Vaught

YEP, WATER INGESTION is one of the key requirements you MUST pass prior to actual production.
I am sure that Mr Seymore's induction design passed with flying colors.

Tom V.

Yes! - but I had a few sleepless nights in the meantime...

Originally Posted by Keith Seymore

We needed to do water ingestion testing but there were no running vehicles at that time. So - what I did was take an existing "old fashioned" GMT400 truck and assembled a GMT800 style front end. I used a hood, RH fender and half a radiator support that I dug out of the trash...

Since hydrolocking the engine can be fairly catastrophic I routed a remote (slave) air induction system at the back of the truck for the actual engine. My new induction system was routed to a shop vac, sucking at the same rate as the diesel engine (to provide the airflow) and which also allowed me to collect and measure any water that got into the system.

I'll never forget the first time we hit the water trough with that setup - it was 16" deep and at 25 mph there was water EVERYWHERE (over the top of the truck, into the pickup cab). I climbed up onto the seat to keep from getting my feet wet. I thought "man, this must be what it was like to be on the Titanic..."

It was a nasty looking thing but it got the job done

K

We argued for months and months about running that test, because we didn't want to (potentially) damage a new prototype engine. Finally we ran a Dodge and a Ford through the trough and they passed, so we knew we needed to do it.

That was my other lesson learned from this endeavor: "Never argue for months over a test that takes 5 minutes to run".

K

[gtospieg]

Just to add my 2 cents...what Tom said...the 67 front end is basically a brick and at any speed above say 20 or 30 mph the air just goes right over the scoop...however it is still pulling cooler air than under hood temps. (my 67 has the scoops opened up with the RA pan).

[Tom Vaught]

Originally Posted by Keith Seymore

That was my other lesson learned from this endeavor: "Never argue for months over a test that takes 5 minutes to run".
K

Before you have data, everyone has a VALID Opinion.
So you have a lot of arguments over what it the best way to do it.

After you have data, lots and lots of those Opinions magically disappear off the screen and now you have a clear direction on what is really happening (OR NOT HAPPENING). Even a Failed Test is good data.

Do stuff for reasons, not because of being pressured by different Opinions.

Tom V.

[Jay S]

I always thought it was curious that NHRA changed the HP on the RA cars and they were different between the 67 and 68-70 cars for Super Stock, but they were identical for Stock. Super stock the 68-70 cars with RA took a 5 hp hit against the 67s. Without the RA the ratings stayed the same. Makes me wonder if that change in the Super Stock rating came from guys opening the 67 scoops up more like what was describe by Seymour and Spieg. Not sure if mods like that are aloud anymore in S and SS, but once NHRA makes changes to index’s because someone was quick, the index’s and specs don’t get change back very frequently. We are working on a 68 Super Stock engine right now, that has make me look at the rules every which way. Lol


Wow, 16” of water would nearly be coming over the bumper.

I live in the Midwest where we frequently have flash flooding in the summer and HEAVY thunderstorms pop up with little warning. We drove up to a street race once and as soon as we got there a huge storm brewed up. We tried to wait it out, but it was getting late so we attempted to drive thru it for an hour, the storm was hardly moving and poured. Had street tires on or we would have had to stop. We where running an air scoop, but plugged it off before we left so we wouldn’t have trouble.

I have ran my shaker hood on my T/A with the shaker cut open in some torrential rain, I could definitely tell the engine wasn’t overly happy about it. Lol…I bet it cleaned the carbon out of the engine. Arid climate probably issues with water never makes someone’s radar. Always was curious how the Hands got along with their set ups in rain, or if they modified the cowl drains. Back when we often raced at the same track, I never saw Jim Hands wagon being towed, he always drove the car in, or out, rain or shine. Weather is something to keep in mind, I suppose it is largely dependent on your location though.

[Tom Vaught]

Air Cleaner Inlet Location is a big deal on a Production vehicle.

We had a few Vortech Supercharged "Mules" that we used for testing.
The SVO Guys were partial to the Eaton Supercharger stuff. (Air Inlet nice and high).

One of OUR "Mules" had a "cone type filter" that was located about even with the bottom of the Bumper.
I tell this story because of Mr Seymore's testing and Jay S post.

The young Engineer/ Supervisor working with us liked to drive this low mount air cleaner Supercharged car to meetings.
So we had a very bad rain storm, one day. The streets were all flooded and Dearborn Michigan has
a bunch of "high" and "low" streets.

You have seen news reports of people trying to drive thru "low spots" after the rain.

Well, that is what he tried to do. Filter dropped below the water level and the running engine immediately "hydro-locked". So he called the Engineering Building, we sent out a tow truck, they returned the vehicle to our garage and we fixed the hydro-locked engine.
We never saw that Engineer/Supervisor again.
Our Chief Engineer had a low tolerance level for people who do not think before they do stuff.........

Ram Air inlet parts located low are not normally a good idea.

Tom V.

[gtospieg]

I did get caught in "torrential rain" once in my 67 GTO with the open scoops while driving on the highway at 65-70 for 2 hours and as far as I could tell there were no detrimental effects. I thought like Jay...it's probably cleaning any carbon deposits off the pistons.

[Formulajones]

Originally Posted by gtospieg

I did get caught in "torrential rain" once in my 67 GTO with the open scoops while driving on the highway at 65-70 for 2 hours and as far as I could tell there were no detrimental effects. I thought like Jay...it's probably cleaning any carbon deposits off the pistons.

Yep, we've been in torrential downpours with that L88 setup I designed on dad's GTO, which is fully open all the time. Didn't affect it at all.

My Formula is open all the time as well, with it's scoops front and center, said to be one of the more effective OEM cold air setups. I've been driving that car for more than 25 years and been in some pretty heavy down pours at highway speeds and never once an issue.


Having them down low below the bumper however where it can scoop up copious amounts of water when running through a flooded roadway, not so good, lol.

[lust4speed]

Seems that most race teams ending up with big holes cut in the back of the pan because the added holes smoothed out air pulses that were disrupting carburetor fuel metering. I took that to mean that a simple ram air setup actually providing ram air effectively could screw up performance because of normal wind buffeting present at speed.

[Formulajones]

Originally Posted by lust4speed

Seems that most race teams ending up with big holes cut in the back of the pan because the added holes smoothed out air pulses that were disrupting carburetor fuel metering. I took that to mean that a simple ram air setup actually providing ram air effectively could screw up performance because of normal wind buffeting present at speed.

I found something similar testing my Formula at the track. The factory ram air setup on this car seems to work pretty good and the car is very sensitive to it.

Every pass I found the crank case vent filter would blow out of it's housing and be laying in the back of the air cleaner. I later found that anything over about 80 mph on the highway would do it, leading me to believe there was quite a bit of air being pushed into the air cleaner. I ended up tying it to the housing (The original was stapled)

So back at the track I tried removing the air filter. That absolutely killed the ET and MPH. It dropped nearly a 1/2 second. I put the air filter back in and all was back to normal. I figured the air coming in was turbulent and the filter helped to slow down and straighten the air flow. To date that particular car has run it's best with that system in tact and functioning with it's stock filter, base, and lid.

[Keith Seymore]

Originally Posted by Formulajones

Yep, we've been in torrential downpours with that L88 setup I designed on dad's GTO, which is fully open all the time. Didn't affect it at all.

My Formula is open all the time as well, with it's scoops front and center, said to be one of the more effective OEM cold air setups. I've been driving that car for more than 25 years and been in some pretty heavy down pours at highway speeds and never once an issue.


Having them down low below the bumper however where it can scoop up copious amounts of water when running through a flooded roadway, not so good, lol.

I thought this photo poster earlier was very telling...

The tires are splashing the water off to the sides and those scoops are way out in front of all that activity.

If the water was up to the bumper - that would be a different scenario. I suspect at that point the water would start to come up over the front of the car, which would be problematic.

Such a great setup. Probably my favorite hood, ever, both from a functional and from a stylistic standpoint.

Very well made, too. Kudos to whomever made those hoods for PMD.

K

[Tom Vaught]

Agree, my story was about the guy driving into a "pond" of water with a low mount air cleaner, IS NOT THE SAME AS PASSING THE TEST IN THE PHOTO FOLKS. A TOTALLY DIFFERENT SET OF CONDITIONS.

Tom V.

[jimib]

I’ve enjoyed reading all of these posts, very educational. I did originally inquire about a cold air intake but when the subject of a RAM AIR setup came up; I liked this idea better. It was suggested above to use the Ames Performance kit; I didn’t know it existed. I would prefer to modify my existing scoop then buy the Ram Air Pan with the seal. Whatever option I chose, the hood will still have to be modified. That is, the area where the scoop drops into, some metal will have to be removed for better airflow. The pic’s I have uploaded are areas that need modification.

Has anyone modified the scoop and hood?

[Tom Vaught]

I have on a 1965 & a 1966 GTO, TAKE YOUR TIME AND WORK SLOWLY, with the proper face shield and gloves and and with patience everything will be just fine. And it will not look like a butcher job.

Tom V.

[taalltheway]

I have read somewhere, that for every 10 degrees centigrade cooler intake air you gain about 1% in horsepower...

[Steve C.]

This from Chevy High Performance Magazine in a related article....

"Typically, colder air improves power approximately 1 percent for every 10-degree F drop in inlet-air temperature."

That said, another opinion.....

“There’s not one standard scale that we use that will show that if you have a decrease in temperature by X amount, you’ll gain Y amount in horsepower,” said Jonathan Fiello, vice president of product development and engineering for K&N Engineering in Riverside, Calif. “You’re going to see significant gains down low and then you’re going to see significant losses up high in terms of temperature, but the displacement of the engine has a big impact on it, and also the fuel being burned, the type of induction, whether it’s forced induction or naturally aspirated.”

https://nasaspeed.news/tech/engine/c...why-they-work/


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