Ram Air Instead of Turbo or Super Charger

My bike is a CBR 600 F4 X reg with ram air. A quick google of my bike and ram air came up with this link.

http://www.sportrider.com/ram-air-test-part-deux

Drew K

I would have done more testing than they did and taken the bikes to the track for testing with the ram air covered and uncovered to see how they do.

You are right, there is no doubt that ram air will help. On a car I think placement would be critical. You want to catch high velocity air so the scoop on the middle of the hood you see on most cars probably wouldn't be as effective as scoops placed at the corners of the hood outside the headlights...I wonder if I could rig something up on my truck and test fuel economy on my next long drive?

Drew k

http://www.americanmuscle.com/mustang-scoops.html?utm_source=bing&utm_medium=cpc&utm_campaign=Sitelink-scoops&sitelink=Hood%20Scoops

Here is a good place to start.

Those are traditionally placed in the center of the hood. From old half remembered pictures of smoke trails across wind tunnel tests I don't recall seeing anything that makes me think the center of the hood is a high pressure or high speed air flow region. Unless your scoop sticks up into the smoke trails and is huge and unsightly.

I would also think that it would decrease the aerodynamic properties of the vehicle. On my bike the air scoops are directly in front of where my knees are and look like they stick out into the edge of the envelope around the bike when at speed. I would hope that Honda did extensive wind tunnel tests to determine the best placement with aesthetics in mind.

If I ever get the time and materials to do this to my truck, I will put the scoops either at the lip of the hood or the corners by the headlights.

Drew K

I agree that the best location would be on the front leading surface of the vehicle.

I think the Mercedes AMG models have scoops installed at both corners of the front bumper next to the fog lights which I assume would provide excellent intake air pressure.

However, I would be concerned that water off the road surface could easily get introduced into the engine.

Both of my vehicles have the air intake cut into the radiator cowling to take advantage of the air pressure generated against the cowling but at the same time protects the intake from water and other contaminates entering.

I don't see why a scoop assembly with a screen couldn't be mounted into the radiator cowling and ducted to the grille so that it would collect maximum air at all times.

I would also think a double intake system such as that on the Ford Taurus HP engine could be adapted.

On my bike, the distance from the scoops to the air box is quite small. I know there are water drains in the system but have not looked at the air path. I know from working at a power plant that dry steam goes around corners but saturated doesn't so well. With all the space under the hood, it would be easy to set up a zig-zag screen to get droplets to hit the sides and drain out.

Drew K

Some of the forced air intakes have a plastic check ball to prevent water from entering the air filter box.

I would bet money that a trip to a local auto recycler would yield a cost effective workable solution.

I was thinking something built into the sides, behind the grill.

It seems that is where the most air is being"pushed" by the car,and would be less intrusive on the looks or aerodynamics of the body.

The hood scoops of my youth did not have enough frontal area,and more or less provided cooler air for the engine,and looked"cool".

I am thinking something along the lines of 1 square foot openings, one on each side of the grill to allow airflow to the radiator unobstructed.

How much theoretical boost could I get from this setup?

Google how to calculate the wind resistance of a shape, calculate the pressure at a specific speed that will give you an idea, but once the engine starts sucking that air the calculation gets much more complicated with partial pressures and probably a differential equation.

Drew K

In the 60's Ford used the 2nd set of headlight buckets for the scoop on the Thunderbolts. The Fairlane had 4 headlights but only 2 were needed.

The "boost" comes from the cold air being gathered outside of the engine compartment, colder air is denser air = more power....theoretically anyways.... certainly does not compare in any way to a boosted setup where a constant back pressure is being maintained...

http://www.redline360.com/garage/cold-air-intake-vs-short-ram-intake-which-is-better

The old NASCAR setup used to draw directly from the cowl....

I agree - you'll get more increased power from the reduced air temp than you will get from "ram" effect. A long time ago I knew the ratio of temp to power increase...something like for every 10 degree drop you could get as much as 1% HP increase...probably wrong but there is a "rule of thumb" someplace I'm sure. We used to love it when the temp at the race track was dropping into the low 40's or even 30's in New England! Of course if it got too cold the track went to hell! I measured the under hood temp, at the air inlet, on one car I drag raced and was amazed to find it at 180 degrees when it was 50 degrees outside...hence I build a cold air system!

Rho V^2 / 2 (at the inlet) must equal Rho V^2 / 2 inside the middle of the airbox. (Rho is static pressure and V is velocity).

Air cfm demand calculator

http://www.csgnetwork.com/cfmcalc.html

http://www.engineeringtoolbox.com/ductwork-equations-d_883.html

Theory is one thing,real world is something else.

The 1967,68 Camaro Z28 5.0 liter, (302 cid) Camaro came with a 780CFM Holley carb.

It was a very good performer,but the performance was improved by adding a larger 1050 CFM carb to it.

This was a power improvement,not efficiency.

There are a lot of dynamic variables,such as intake manifold design, valve overlap and,exhaust system design, and many others that muddy the straight formula.

It is,however, a good starting point.

Be careful with too large of a carb. Case in point - years ago, I had a 1980 Camaro with a 5.0L V-8. My friends helped me with a tall/long duration cam, bigger heads, headers, no cat with 2 1/2" pipes and turbo mufflers, taller dual plane intake, roller timing chain and 3.31:1 posi. We put a Holley 650 double pumper on it - given to me by my cousin - he took it out of his Camaro with a 350 - he said he didn't like the feel of it and put he Quadrajet back on.

1050 CFM is definitely too big for a 302 V-8.

A lot depends on the setup,of the carb and the engine.

Bigger is not always better,but sometimes it is.

I had a '68 Z28,302,highly modified,"full house",as they used to say.

Sodium filled exhaust(McGurk,I believe?) valves, dry sump, R322 cam,etc.

Been along time,the cobwebs are forming after all these years.

The 1050 CFM dual line Holley gave much better 1/4 mile times than the standard 780 Holley.

Shift points at 7800rpm,I believe,but knowing Skeeter,he probably shifted when he wanted to.Man!That guy was rough on shifters and trannies!

Ran 11.55 seconds/118Mph.

The Holley is a better race carb;the Quadrajet is better for economy and general drive ability because the tapered needles feed the fuel proportionally.

It will "feel better" on the street,and to the uninitiated driver.

The Holley has a power valve that dumps lots of fuel when the engine manifold absolute pressure goes above a certain amount,determined by the power valve spring.

(Standard spring I believe is around 6.2 Inches H2O.)This is much too rich at idle for a highly cammed engine unless you drive it hard.

You will need an auxiliary vacuum pump if you try to drive it on the street with a radical cam and power brakes.(Not enough vacuum at idle to operate the power brakes.)

There is a lot of art to the science of high performance engines, and both fields are necessary to compete successfully.

7800 rpm on a 302! My 305 Camaro had a red line around 5,500 if I remember correctly. I'd push it to 5800 or so at times, but it always scared me. One of the kids in high school had a Shelby GT 350 Mustang (69 or 70). He was in the school parking lot revving his engine and then boom! Threw the rod! He had to have the car towed home and had to face his daddy!

I agree that the Holley is a better race carb - my 650 was a double pumper and it can pour a lot of gas into the engine. I know the Quadrajet was a better carb for daily driving, but I never liked it.

My Camaro had a cammy idle - rumple rumple rumple! It didn't do very good on gas mileage in the city - maybe 11-12 mpg or so. I used 1.94/1.60 heads per the advice of my smart friend - I think it was a good combination, though many of my other friends thought I should've gone with the 2.02's (they're the ones who said I should've gone for 350 block - bore it to 4.060, throw a 400 crank, put an 850 cfm carb and a 4.11 axle). I'd be dead if I listened to them. The exhaust had that unburned gas smell too! But when I stomped on it, that car sure did move. It had a really nice sound - my friends said it sounded like a NASCAR engine! I never took it to the track, but my guess is that it ran around 14s. I did get it to 135 mph a few times - the chassis/suspension was not made for that much speed and it didn't feel very safe. I have driven my 911 (996) to 154 mph - had a lot more to go and my Boxster (986) to 155 mph - topped out. Both felt pretty good at that speed, though the 911 did feel a little light in the front end. The Boxster felt like it could go all day at that speed!

Thanks for sharing your Z28 with us. You really had a 1/4 mile race car!

This engine was balanced after mods,including the pressure plate and clutch attached.

On a day,when I was slightly inebriated,I revved it past the end of the tachometer on a power shift,(which was a Stewart Warner 10,000 with remote sender unit)and then hit 2nd gear.

It pulled the front wheels and I had to back off just to steer.

I was challenged by a new 390 Javelin on a make-shift 1/4 mile.

He hung with me through first,which is why I delayed the shift...not a wise move,but it held together.

After 2nd gear it was bye bye AMC.

I crossed the line at about 6900 rpm in 4th gear.

No measurement of et or mph,this was a "Red Nek DARE YA"

I was just trying to stop before the end of the track.

There was a sand trap and a pond at the end of the track.

If the sand didn't stop you,the water would.

Adrenaline will sober you right up.

A 3inch stroke can really turn up the revs with a fuel flame front of 6800 fpm if your engine will take it.(Theoretical with pump gas is 13,600,but no one comes close.)

The Ford 289's with a 2 7/8 inch stroke could turn even higher.

A friend of mine with a built up 289 consistently shifted at 9000 rpm.

IMHO, the Z28's lost their nads when they put 350's and automatics in them.

Over 10K rpm is insane! That engine must've been screaming! I would've loved to hear the sound of it!

Those short stroke engines were really good revving engines, but I've always wonderered how the bottom end held up and I can only assume that valve float had to be a problem.

These new engines are incredible and we're seeing. The last BMW M3 revved to 8,400 rpm for a V-8, 444 hp at 8,300. Quarter mile 12.3 sec.

I think the yamaha r6 had a red line at 17500 rpm, but on the dyno nobody ever quite saw that high.

In my Nissan pickup I have hit the limiter a few times when trying to squeeze into traffic but for some reason I am never looking at the tach when riding the bike hard; I just shift when I feel the power start to drop off.

Drew K

When we were in high school (early 80's), my friend had a Ninja 250R with a 14K red line - something crazy like that. That bike would scream down the street! We loved running it at red line!

One day, we got some "hi test" gas - I think it was 108 octane or something like that. I believe it was at a Clark Gas Station and it was at a separate pump. They called it racing fuel! The bike was insane with that gas! Revved so fast and sounded so good!

17.5K is super high, but with the technology improvements, another 3.5K RPM improvement over 30+ years is reasonable.

A big V-8 from the 60's running at 10K RPM is a different story! That's a lot of mass to be turning at a high RPM!

Formula one car engines are capable of 20000 rpm,but are limited by rules to 18000

They are V8 engines.

NASCAR engines run all the time at 9000 rpm,the full race.

Hot Rod magazine,1968 said that the stock 302 Z28 could be run from coast to coast

in first gear without damage.

It had 4bolt mains,oversized main bearings,2.02 swirl polished valves.

I upped the ante with triple spring rockers,sodium filled(very light) exhaust valves,a

.030 overbore,11.5 to 1 compression,copper o-ring sealed head gaskets,a hotter

cam,and precision re-balancing of all moving parts,including the flywheel,pressure

plate and drive shaft.

You could buy real gas back then,and I ran Sunoco 260.

Don't remember the octane but it allowed me to advance my timing higher than any other brand.

A lot of money spent in my foolish youth,but I could get it all back now if I still had the original engine and car before mods.

The 302 was the best Chevy engine for running higher rpms, due to the short stroke - less piston velocity, thus less force on the bottom end. Running your engine to 10,000+ rpm is impressive - something that I wouldn't recommend, but very impressive. The build on your engine sounds nice - I would've loved to have an engine like that in my 1980 Camaro!

As you know, F1 engines are crazy expensive, have technology not seen in production vehicle engines, have a super short stroke, have very low moving mass and have a small displacement. Yes, a V8, but nothing like anything you or I will ever have in our car.

And NASCAR engines are also expensive, though not in the same league as F1. NASCAR engines are larger displacement, short stroke (like your 302) V8 engines. 9,000 rpm - high, but when you're dumping $100K+ (price for a 2015 NASCAR engine) into an engine, you can build it strong - I'm pretty sure that a quick push to 10K rpm wouldn't be detrimental. Titanium valves to lower valvetrain weight. I guess you could put one in your car and use it as a daily driver, but that's a lot of money for performance that would rarely be used.

I had a one-cylinder Ducati 250 that was very octane sensitive, really liked Sunoco 260 and Amoco hi-test, which was called 'white gas'. It ran poorly on regular gas. Long stroke and high compression made for a very picky engine.

Depends entirely on the shape of the vehicle.

As SE indicated, NASCAR still takes air from the cowl area. They don't do anything by chance.

Besides ram air, consider scavenging the exhaust to reduce load on the engine pushing the exhaust down the pipes, through the cat and muffler, that's a long trip.

I always thought a simple tee on the exhaust that was fed to the side of the vehicle facing forward would do the job simply. A cute little flare on the intake would ram air past the exhaust, and good ole' Bernoulli would take over and pull the gasses out. One on each side, all the cooler. Just don't have them sticking out too much so they hurt people.

A properly designed exhaust system will actually assist the exhaust,by timing the pulses of the preceding pulse to assist the following pulse.

After each high pressure pulse,there is a negative pulse that "echoes" from the end of the pipe back to the beginning.

If this is designed properly,each preceding pulse will "suck" the next one partially down the pipe.

This is one reason that some headers have the elaborate curves in them.

Length of tubing is critical and affects performance.

There is no "perfect length," due to variable RPM,temperature,etc.,so a compromise is reached,based on desired performance level.

A wide open (cut out) exhaust is not always the best.

If you want to feel this effect for yourself,take an empty garden hose,and blow down it with a full breath.

Hold your mouth on it,and wait a couple seconds,and you will feel the negative return pulse.

It is similar to an echo effect,and the oscillation will continue and decrease in amplitude as long as you block the end.

Your Pitot tube is a good idea,however,as long as you can ensure that the air entering is a higher velocity than the exhaust.

Thanks, HiTek, for the good post. I look at most cars (except for the Jag XKE) as having poor aerodynamics. Basically they are pushing a billboard down the highway with that large flat front. Putting an intake in that front, like some who put intakes beside the headlights, would make me think that would reduce the theoretical frontal area, by creating a low pressure area there, or at least reduce the high pressure there somewhat.

My exhaust idea appealed to me because it's easy to do, and any little bit has to help, especially at turnpike speeds. Stick your hand out at 70, that's a lot of air pressure.

Same as the late 1980 to 1981 Z28. http://www.wc-autoparts.com/1980-81-camaro-cowl-air-induction-hood-scoop-assembly/

And the 70's Trans Am with the shaker hood.

You can't figure on more than about 4% increase in air density over delta 10 degrees Kelvin / Centigrade.

With a strictly ram scoop I bet you wouldn't like the trade-off in air drag to get any where near the density increase of a Kompressor.

Drawing exhaust out is intuitively enhancing for the engine except it won't work properly without back pressure.

It depends on numerous factors, is it carburetor or injection. If injection you may be all set to supply some ram air with success all parameters considered. If the vehicle has a carburetor then remember these items run on pressure differences so if you ram air into the carb then you may not get sufficient fuel. If you enclose the carb in a airtight box and fill the box with air it will work better but for every degree of added pressure in the box you will have to make sure the fuel delivery system can overcome this added pressure. Remember Paxton Superchargers they even supplied pressure to the atmospheric side of the fuel pump to over come this issue.

Your biggest advantage to ram air would in my experience be the cool moist air from outside the vehicle v/s under hood sources. The cowl of the vehicle may be the highest pressure point for ram air similar to most older muscle cars and the Ford Heavy Trucks with the 534 CI gas engines from the late 50's.

You should look that the late 60's and early 70's pony cars that featured Ram-Air. Let the expertise of the auto engineers back then work for you in regard to scoop placement and size.

I once owned a 1969 Pontiac Trans-Am w/ 400CID block, 4:11 rear end, M22 manual trannie w/ Hurst 4-speed, and fully functional Ram-Air IV. I am positive that the Ram-Air on that car was highly effective, and not just a cosmetic slap-on. Both scoops were located right up on the hood and were slightly off-centered to car and engine centerline.

Oh my God, how I miss owning that beauty! I can't afford to buy one now days!

http://www.conceptcarz.com/vehicle/z8901/pontiac-firebird.aspx

https://www.youtube.com/watch?v=ptwQC-ed5Rg

You think the 69's are expensive! Look at what the 73 Super Duty's are pulling!

$175K - http://classiccars.com/listings/view/743805/1973-pontiac-firebird-trans-am-for-sale-in-halton-hills-ontario-canada-l7g-4s6

YIKES!!!!!!!!!

A couple years ago, I noticed that the 60's era muscle cars had weakened (except for the ultra rare cars), while the 70's so called muscle cars have skyrocketed. The older Porsches have jumped too. Look at the prices of the old 356's, short wheel base 911's, 911 Targas, 912's, air cooled 80's 911's, BMW 2002's, e30 BMW's.

We sold our 1967 912 and our 1970 911 for nothing years ago!

Back when I was Crew Chief for a NASCAR team we would use a magnehelic to check for an overpressure inside the air filter while at full throttle on the track, the filter being connected to the cowl and sealed air tight. I don't recall what measurement was being used but if I recall correctly the best you could achieve was a positive pressure of 7 while the engine was consuming its maximum cfm of air. It was very easy to obtain a negative pressure and that was no good. You would see some teams connect a hose to the float bowl vent tubes and run this out to the outside top of the cowl area (if this was in a lower pressure area wouldn't it pull fuel out of the bowls)? they said it was for squirting fuel into the fuel bowls if they ran out so they could start the engine easier.

We had a very well enforced set of dimensions to work within and this made it really tough to obtain a good number. Without any restrictions on what you could do you could easily obtain a good positive pressure. If you were going to be competitive you better get this right. Just think of what a 1% increase on 800 horsepower would be and how that would help at 200 MPH? You would see teams bring boxes of cowls with them to testing so they could make changes looking for the most advantage. In another post I read it was mentioned around 1 HP per 10 degree drop in temperature, what I recall is 1 HP gain for each 7 degrees drop in air intake temperature.

The modern pro stock drag racers can tell you about ram effect but the story they will tell is only a partial story, they have researched how to squeeze every ounce of air they can get into those 500 CI (or much bigger in the IHRA) grenades they drive.

In theory (of course) it can generate some positive pressure above the throttle blades above a certain MPH but to most those speeds are unobtainable.

In my hey day using calliope tube injectors with auxiliary jets in the tubes (on methanol) I could put a tremendous amount of ice on the tubes and manifold from the cooling effect of the methanol on the incoming air stream and get a hell of a lot of seat of the pants power (on clocks about .02 sec) in my quarter mile crusades, never bothered with air box and snorkel stuff cause I liked the psychological effect of those pipes sticking out of the hood had on my opponent.