I finally figured out how to get the filter in front of the radiator! Made a very significant difference in performance. Great thing is I didn't even have to cut any holes to do it! Took advantage of that opening between the lower valence panel and the lower radiator support.

I scoured the wrecking yards for the correct tubing I needed. There's TONS of different air duct designs to choose from. Was able to come up with this design. Which is cool because I'm only one step away from a true ram air setup.

This setup is good on two counts...

1.) picks up cool air from in front of the radiator. At idle, air temp readout will climb to a maximum of 12°F over ambient temp (compared to over 60°F ambient with my earlier setup.). When driving at speed, I'm only about 5°F over ambient. It ain't going to get much better than that.

2.) At speed, higher air pressure builds up in front of the car which this filter location takes advantage of- a very minor supercharging effect. But I may put a MAP sensor there temporarily just to confirm what the air pressure is.

Anyway, this thing is in "proof of concept" state only. I may try to improve on it later. But I'd say concept proved at this point!!

http://a.imageshack.us/img6/9726/img5246v.jpg
By ultm8z (http://profile.imageshack.us/user/ultm8z) at 2010-08-08

http://a.imageshack.us/img197/8923/img5247s.jpg
By ultm8z (http://profile.imageshack.us/user/ultm8z) at 2010-08-08

I've never really understood how "Ram Air" works if it's got to go through such a thick filter.
Can't see it ramming much of anything. But the concept of getting colder air is obviously desirable.

Ace, it's not necessarily "ram air". What I'm theorizing is that instead of drawing air from 14.7 psi ambient pressure, I positioned the filter in a region of the car that is building air pressure to say 15.5 psi at high speed. It's akin to a supercharging effect. Like I said, I'm going to put a MAP sensor there to confirm this at some point.

I bet its doing as you are figuring with a small amount of increase in pressure in the intake system.

can you post more pictures? What did you use to connect the cool air lines to the carb? Pics of that? Under hood pics too.:)

Thanks!

Well, it's actually an EFI set up, not a carb. But I'm sure the same thing can be adapted for a carb.

I'm using a TPI duct that hooks up to the TB. From there it goes to a flexible 90 deg connector from Home Depot, then to a piece of 3" ID ABS pipe. From there, it connects as shown in the above pictures.

This picture is a little dated (before I added the Taurus fan), but the ducting is pretty accurate.

http://ultm8z.com/Engine2.jpg

Have you ever seen the air filter / intake on earlier Hurst Olds cars??

It's got 2 shovel intakes on the bottom of the front end that go into vents
to the side of the air cleaners. I've always wondered if I could create something
like that.

Nice Job !

Just dropping the temp will give you a decent boost. Supposed to be 1% for every 10-11 degrees of inlet temp drop assuming you jet for it. EFI makes it almost stupid-simple. So you should be getting an almost 5% boost in free HP. Assuming you have 400 hp to start, thats 20 free horses. Add in any ram air bonus, and you're looking really nice.

A home made setup on my V-8 Monza made a 3 tenths difference in the 1/4 mile. Yours should do more.

A home made setup on my V-8 Monza made a 3 tenths difference in the 1/4 mile. thats great cheap horsepower, man i need to do this to my camaro, hmmm....

Nice Job !

Just dropping the temp will give you a decent boost. Supposed to be 1% for every 10-11 degrees of inlet temp drop assuming you jet for it. EFI makes it almost stupid-simple. So you should be getting an almost 5% boost in free HP. Assuming you have 400 hp to start, thats 20 free horses. Add in any ram air bonus, and you're looking really nice.

A home made setup on my V-8 Monza made a 3 tenths difference in the 1/4 mile. Yours should do more.

This setup cost about $35 between the wrecking yard and Home Depot. Not bad if I do say so myself. Though I'm not sure about the 420 hp thing... I simply don't have the cam to produce that kind of power. I think what I'm getting is the benefit of not losing power when things get hot under the hood.

Nice work Mike!

The big gain is getting unheated air into the intake. While your EFI might be able to compensate for a bit of raised pressure from 'ram air' or 'supercharging', guys with carbs reading this will quickly learn that if they try to ram air into a carb and are successful they will go lean unless they raise fuel pressure accordingly.

If it was easy, we'd all have Hemi scoops on our hoods.

The only thing that's bugging me a little about this is the length of the tube and the resulting pressure drop. Going from ~140 degF intake air temp down to 80 degF (on a 70 degF day) I did pick a VERY significant amount of streetable torque, but at the top of the RPM range am I losing horsepower from too much pressure drop along the tube length (particularly where the tube makes those turns under the radiator support.)

What I think I'll do is run my Autometer vacuum/boost gauge into the cold air tube right at the throttle body and see how much below 14.7 psi the engine is seeing during a full throttle blast to 6000 rpm. I'll reposition it at various places along the tube and see if where (if any) the restrictions are. It'll be an interesting little experiment anyway...

Yeah, that's the problem with long air inlet systems. Even if the filter is in a high pressure area you end up losing it (and more) to the LONG, TORTURED intake path. That's why most modern systems keep the length short, straight and just "box off" the filter element from the rest of the engine bay, leaving the only path in for the air from the inner fender.

Remember, that even an optimal "ram air" system can only add about 1% to engine output at 100 MPH forward velocity. Those numbers climb signficantly as speed increases (I believe it increases by either the square or the cube of velocity). Regardless, at 100 MPH the difference is very slight. Easily overwhelmed by even a slight restriction in the intake system, or by temperature effects.

In order of importance they go like this:

1. Non-restrictive.
2. Draw cold outside air
3. Draw air from a pressurized source

Don't trade off 1 or 2 to get more of 3.

Yup. A friend of mine has seen this first-hand with the CAI on his Beretta. He has a couple hundred passes on it and decided to take the filter off the CAI and throw it right on the throttle body just for shits & grins at a test & tune. Gained 2-3mph IIRC. And from what I understand, the accordian flex tubing makes it even worse than the smooth mandrel bends of his CAI (and mine, that I will be doing some experimentation with at the track).

http://media.motortopia.com/files/cars/album_finishingtouches/4c47aaeba0a92/tn_full_IMG_4547JPG_Thumbnail1.jpg

Ace, it's not necessarily "ram air". What I'm theorizing is that instead of drawing air from 14.7 psi ambient pressure, I positioned the filter in a region of the car that is building air pressure to say 15.5 psi at high speed. It's akin to a supercharging effect. Like I said, I'm going to put a MAP sensor there to confirm this at some point.

You're not going to get anywhere near 1 psi difference at the front of your car at any speed you may be able to drive it. You're looking at a couple inh2o, less than 0.1 psi.

Admittedly the 15.5 psi number had no basis in fact… I pulled it out of thin air and was using it to simply make a general point.

Nonetheless, it'll be an interesting study to map the pressure drop at various points along the length of the tube. My Autometer gauge doubles as a boost and vacuum gauge, so I can measure positive and negative pressure. I'll plumb it into the tube and then a few of 6000 rpm blasts and I can get an accurate measurement of how much pressure I'm losing from ambient as I move from the filter to the throttle body.

Again, this was a proof of concept design for temperature reduction, and clearly I picked up a significant amount of torque in the midrange by dropping the air temps by ~75°F ( though it remains to be seen at what cost to the top end horsepower). There's obviously room for improvement in the design to minimize top end losses. But if I ultimately measure an acceptable pressure drop, I may just consider it a worthwhile trade off for a street driven car that spends 95% of it's time below 4000 rpm.

what about utilizing the cowl area, just get rid of the wipers and motor ??

... And from what I understand, the accordian flex tubing makes it even worse than the smooth mandrel bends of his CAI ...
I've read that related to those flexible rad hoses, so i wonder if that is the same principle.

what about utilizing the cowl area, just get rid of the wipers and motor ??
an ls motor with the intake mounted backwards!

I've read that related to those flexible rad hoses, so i wonder if that is the same principle.



I doubt it. Comparing an (essentially) incompressible fluid to compressible one in terms of flow characterstics is not particularly valid IMO.

http://www.speedcircuit.net/images/Autometer_Phantom_Boost_30PSI.jpg

2 or 3 inh20 is less than the width of the needle on your gauge. The zero box is about 40"h2o wide. Not a lot of resolution there. You'd be better off making a simple u-tube manometer.

http://www.speedcircuit.net/images/Autometer_Phantom_Boost_30PSI.jpg

2 or 3 inh20 is less than the width of the needle on your gauge. The zero box is about 40"h2o wide. Not a lot of resolution there. You'd be better off making a simple u-tube manometer.

I'm talking pressure drops internal to the tube. My gauge reads out in inHg for vacuum. 2 inHg is one PSI and my gauge has that kind of resolution. I'm not going to get >14.7 anywhere in the tube, so it's really the vacuum side of the gauge I'm interested in.

Worse comes to worse, I can hook up a voltmeter to a MAP sensor, send 5V into it and read out the voltage drop. There's a curve for voltage drop vs pressure for GM MAP sensors I can use to do the conversion.

I think onovakind's point is that the pressure drop is going to be hard to see, because the actual drop may well be in inches of water, so it's not going to resolve well on a inHg gauge.

Case in point- we run 4" hard lines at work for gas box exhaust. They pull over 300cfm, and the pressure drop is in the 400 pascal range- that's about 0.1 inHg.

How did you get a 75F drop? I don't recall it being that hot under cruise even with my open element. At a light that's different, but I can't imagine average underhood ambient temps staying >150F at cruise. You're making me curious enough to test my setup.:)

I think onovakind's point is that the pressure drop is going to be hard to see, because the actual drop may well be in inches of water, so it's not going to resolve well on a inHg gauge.

Case in point- we run 4" hard lines at work for gas box exhaust. They pull over 300cfm, and the pressure drop is in the 400 pascal range- that's about 0.1 inHg.

How did you get a 75F drop? I don't recall it being that hot under cruise even with my open element. At a light that's different, but I can't imagine average underhood ambient temps staying >150F at cruise. You're making me curious enough to test my setup.:)

If I can't resolve a pressure drop in inHg, I'm going to consider it trivial relative to the torque gain in the mid range.

My throttle body can flow a maximum of 750 cfm, and it's through a ~3" duct. Assuming I'm using the entire 750 cfm at max horsepower, it's over double the flow rate and in a smaller diameter tube. Velocity varies with the square of the diameter, so between increased flow and decreased diameter, it's a double whammy on air velocity.

Question on your gas box exhaust would be how long the lines are. Length is a signifcant contributor to pressure drops as are changes in direction.

As far as temperature, around town at low vehicle speeds and stop and go traffic, I routinely saw temps pushing over 140F- particularly on hot days. Keep in mind you have exhaust headers running at >400F dissipating heat into the engine compartment and a radiator dissipating heat from ~200F coolant, and the engine itself has some convection cooling off the external surfaces dissipating heat into the air in the engine compartment.

You're definitely in the "try it and see" realm.

Keep an eye on the temps and the MAP readings. But remember that the MAP readings are likely to show a significant restriction from just the throttle body and design of the intake plenum. Late model LT1 guys were always wondering where that last inch or two of vacuum was holding them back in the intake tract. The answer was partially the TB and intake plumbing but mostly the overall design of the intake (just too small) when the engine underneath was a real heavy breather.

Temp reduction always helps, at ALL RPMs. The rule of thumb is that every 14*F reduction in temp is worth 1%. So 70*F temp reduction is worth about 5%, if the tune can take advantage of it. That's about 20HP on a 400HP engine. But it's also 1% EVERYWHERE in the RPM range. Even if the intake is restrictive to the point of completely offsetting the temp reduction gains in the upper RPMs you STILL get the benefit all the way up to that point! In short, you can go faster without making any more (or even slightly less!) peak HP. Explains why your engine felt noticably stronger in the mid RPMs quite nicely, doesn't it?

If you think about it long enough your head will explode. So, this is a situation where trying different things is probably going to yield bigger dividends than trying to think your way through it.

Keep an eye on the temps and the MAP readings. But remember that the MAP readings are likely to show a significant restriction from just the throttle body and design of the intake plenum. Late model LT1 guys were always wondering where that last inch or two of vacuum was holding them back in the intake tract. The answer was partially the TB and intake plumbing but mostly the overall design of the intake (just too small) when the engine underneath was a real heavy breather.


Understood. But yeah, what I'm talking about is a separate measurement at various points along the intake tract and ahead of the TB.

an ls motor with the intake mounted backwards!

Think about that. An intake designed to take air right from the base of the windshield. Seems like kind of an obvious thing to do.