Stock Air Flow Numbers and Mod

[Mr. Creosote]

The same can be said about every performance mod ever developed since cars first appeared 100 years ago. There are mods that work, and others that don't, and the airbox mod discussed above is among the former.

Toyota does not design their airbox this way because it would make too much noise. They must compromise performance to provide an intake system that meets their noise constraints.

Rent yourself a factory stock Dodge half ton with Hemi and spend a Friday night at a local dragstrip running against guys with the same truck but with lots of simple, cheap bolt on mods. Feel free to lecture them on how "Dodge engineers would have used these mods if they actually did anything". Let us know what happens at the end of the day.

[Highwaylizard]

Hey guys,

Sorry for the delay in getting back on this one. I have been homeless for the past two months until my Godfather and his wife took me in. I just landed a job about a week ago and have another week of unpaid training before I can get out into the field and start earning some money, and as you know the bills do not stop coming. I lost a marriage and a business this year along with my mother who lost her battle to ovarian cancer. Absolutely the most difficult year of my life but I will battle back and get on my feet.

So here is the latest. Winter time fuel is here and the mileage has taken a significant hit. Running the defrosters and mostly in-town driving has the numbers down around 15 MPG. The real numbers are going to come this summer when I can compare them to last year's numbers. One thing I have decided is that I do not like the scoop this low to the ground when the roads are salted as the airborne salt is getting drawn up into the air box. I have completed design of and am fabricating a smaller scoop to sit up in the grill much like the RAPS set-up.

In changing out the scoops I noticed that the aluminum flexible tubing had rotted out where it connected to the stainless steel collar. Going to have to address that as the lesser metal is always sacrificed to the greater metal on the hierarchy chart.

At any rate, here are a few pics for you.

[vincas2005]

thats all Ok, but keep +30HP +20MPG for local ricers meeting. Prove it - dyno it. 30HP from extra hole in airbox is unheard of in automotive world. And little noise can be dealt with. As someone said - if you can put Supercharger on stock engine and use same airbox, then its more than capable of supplying air for stock engine. So the whole hole thing and running ET on the drag strip is BS. When you'll have +2000 runs down the strip and will feel the ET time on your trained BUTT CLOCK then come here and make claims that were said above by OP.
1st what all reputable engine builders do is DYNO the darn thing to determine HP/TQ gains if any, and only then to drag strip. Second cannot compare two different vehicles even the same model and judge HP by how fast one finishes ET. Thats like guessing your future by looking at the palm or similar.] I do agree that to some extent these claims are valid, but i will put my family jewels on butchers board to cut of if one makes +30HP extra as claimed.

The same can be said about every performance mod ever developed since cars first appeared 100 years ago. There are mods that work, and others that don't, and the airbox mod discussed above is among the former.

Toyota does not design their airbox this way because it would make too much noise. They must compromise performance to provide an intake system that meets their noise constraints.

Rent yourself a factory stock Dodge half ton with Hemi and spend a Friday night at a local dragstrip running against guys with the same truck but with lots of simple, cheap bolt on mods. Feel free to lecture them on how "Dodge engineers would have used these mods if they actually did anything". Let us know what happens at the end of the day.

[Mr. Creosote]

thats all Ok, but keep +30HP +20MPG for local ricers meeting. Prove it - dyno it.

I don't care about mileage. It improved my quarter mile time by three tenths consistently. If you wish, you could reproduce these mods and conduct your own tests on a chassis dyno.

As someone said - if you can put Supercharger on stock engine and use same airbox, then its more than capable of supplying air for stock engine.

How do you explain the restriction (vacuum) measurements observed by the OP? Moreover, do you have any test data from a supercharged application to back your statement?

So the whole hole thing and running ET on the drag strip is BS.

On what scientific basis are you making this conclusion?

When you'll have +2000 runs down the strip and will feel the ET time on your trained BUTT CLOCK then come here and make claims that were said above by OP.

Please explain the statistics behind the need for 2000 passes? How do you arrive at this number?

1st what all reputable engine builders do is DYNO the darn thing to determine HP/TQ gains if any, and only then to drag strip.

If dragstrip testing is BS, why would reputable engine builders go there at all?

Second cannot compare two different vehicles even the same model and judge HP by how fast one finishes ET. Thats like guessing your future by looking at the palm or similar.
.

Yes you can. There have been software packages and mathematical formulae for decades. Try googling "quarter mile simulator".

[Hi Volt]

Hey Mr. C

Kinda nice to see this post has kept somewhat alive. Seems you are doing alot of charity work trying to educate someone that doesn't understand the effect of residual WOT vacuum let alone the potential of dragstrip information, particularily the value of a repeatable timeslip that has nothing to do with butt dynos, or butt clocks

As far as the earlier comments as to why the factory wouldn't have done this mod ? Well it wouldn't have been a mod in the design and testing stages of the engine. All initial engine proving and certifications are done on an engine dyno with the transmission and ancillary components attached ( air box included). I wouldn't doubt they didn't see any residual vacuum, there shouldn't have been any fender to draw restricted air from ( at least restricted air measured in my case and confirmed by some that have done the actual mod.) Even CARB engine certs are done the same way ( this method allows the same engine to be used in any lighter chassis under the same cert which is cheaper than chassis certing every model using the same engine.) With this being said, similar issues could be present on other brands of vehicles using similar air intake systems, then again perhaps the gen 1s are an anomolie. All I can say is the vacuum readings were repeated a number of times and they can be taken for what they are. Some will fully understand the importance, others will not.

[tundrunk]

I wasn't picking a fight bud, just saying it would take a few days. I don't believe in the butt dyno either, it's nonsense for the most part. At least when talking about minor 5hp gains, bigger gains can be felt, but not small ones. I go back to your statement about tire pressure and such variables, that can have enough bad effect to cancel any 5hp gain "feeling".
I also dislike mpg counting, it's a truck, not a prius. Most of us aren't scientific enough to do it properly. But if they want to count, that's cool. Highwaylizard is doing some cool experiments and I appreciate innovation. His newer design is better, there's a pic of it somewhere, the scoop is improved for directional flow.
Sorry for the bad feelings I may have given you, I'm not mad at you.

[E-DUB]

Read thru this whole thing, sounds like a great Idea! Hi-volt actually has data to back up his work, on a modded Tundra. Which for the average joe is hard to come by other than going to the track. To the guy who said take it to the dyno, why? This mod seems to work best with airflow from a moving vehicle, which you cannot duplicate on the dyno. Oh and btw not everyone has friends that can dyno thier vehicles all day for the price of a pizza. But IMHO this mod does seem like it just further compliments headers and exhaust mods.

[Hi Volt]

Hivolt,

Can the air flow into the original inlet opening into the space behind the wheel well be improved, instead of increasing the cross sectional area of the inlet into the stock box? For example, a functional side vent could be placed in the sheet metal of the wheel well, or a ram-air scoop could be placed there, or some of the plastic trim could be removed.

Tell me what you think, and thanks for the good ideas!

You may be able to do some limited forced air improvement, however there are two issues I see. The first is the narrow area you have to play with in the fender, the air would need to take a sharp 90 if you were to try redirection. Trimming the plastic to allow more air into the fender area would increase the risk of water being shot up by the tire. Before getting too complicated with fabrication, my suggestion would be to pick a dry day and install a vacuum gauge in the engine intake and first see the residual vacuum you have at WOT. Next I would remove the inner plactic skirt and then try it again. If the vacuum does not drop to zero under WOT then I would suggest the airbox inlet tube is too restrictive. If you do in fact reach zero vacuum under WOT, then a mod to the inner fender area may be your answer.

[redbaronace]

bump for future mod

[Highwaylizard]

Hivolt,

Can the air flow into the original inlet opening into the space behind the wheel well be improved, instead of increasing the cross sectional area of the inlet into the stock box? For example, a functional side vent could be placed in the sheet metal of the wheel well, or a ram-air scoop could be placed there, or some of the plastic trim could be removed.

Tell me what you think, and thanks for the good ideas!

I tested various locations for best air pressure using a homemade manometer and found some interesting results. Tundra Fuel Economy: Manometer One of the locations I tested that you referenced was on the sheet metal of the fender well and I was surprised to find that this was a poor location. I had received numerous messages from people telling me that with my scoop located under the front bumper it was in an area of negative pressure but my testing found this not to be the case. I am currently in the process of fabricating a new scoop out of black ABS and will locate it in the bumper which will improve both the pressure as well as the route to the air box.

You may be able to do some limited forced air improvement, however there are two issues I see. The first is the narrow area you have to play with in the fender, the air would need to take a sharp 90 if you were to try redirection. Trimming the plastic to allow more air into the fender area would increase the risk of water being shot up by the tire. Before getting too complicated with fabrication, my suggestion would be to pick a dry day and install a vacuum gauge in the engine intake and first see the residual vacuum you have at WOT. Next I would remove the inner plactic skirt and then try it again. If the vacuum does not drop to zero under WOT then I would suggest the airbox inlet tube is too restrictive. If you do in fact reach zero vacuum under WOT, then a mod to the inner fender area may be your answer.

Hey Jeff,

The room in the fender well is tight but I got a 3" flexible aluminum gas vent tube up through the fender well from the Ram Air Intake Scoop to the air box. It is sealed thereby drawing no warm air from the engine bay and it builds pressure at speed which overcomes the residual vacuum you refer to. When I got the truck I was getting around 15 MPG on the highway at the speed limit. I no longer drive the speed limit and I get low 20's.

[arseum]

This is where I located my scoop. It was $40 or $50 made for a 5.0L Mustang I believe, and the $20 Spectre duct is a universal item from Autozone, I believe. So this is the second best location per your testing...

[Highwaylizard]

Attachment 79751Attachment 79752

This is where I located my scoop. It was $40 or $50 made for a 5.0L Mustang I believe, and the $20 Spectre duct is a universal item from Autozone, I believe. So this is the second best location per your testing...

I have seen some of these types of scoops before. I think Banks makes some too. One thing about me that concerns me is the off-set of the tube in relation to the face area of the scoop. Maybe in a few weeks I can have the new scoop fabricated and installed. Kind of busy recovering from being off work (due to illness) and have some catching up to do. Have you measured your intake temperatures with this set-up? Any improvements? What kind of filter are you running in the air box? Really cool to see someone else doing this too.

It looks like your truck is lifted. Thanks for the lead on the duct - what material is it made out of? I would like to get away from the aluminum. Can you post up some closer pictures of how the duct is routed from the scoop up into the fender?

[arseum]

The Spectre duct is literally a Heavy Duty dryer hose. It just is a thicker plastic material, and thicker gauge rigid spiral wire along the ribs. You can compress it, or pull it out, and it conforms to how you direct it. I cannot recall how long it is, but somewhere in the range of 24 to 32" inches. If the scoop were moved any further away, it would not be long enough. It has two identical rubber ends that screw on. These rubber ends fit perfectly into the stock air box, after the stock thru-fender-wall plastic piece held in place with its one alum rivet is removed, and the other end fits nicely into the rubber adapter fitting I found at lowe's, which then fit perfectly around the scoop, which has a 4 or 5" diameter outlet. I wonder if you can somehow call spectre and get this in custom lengths?

I believe I only had to remove 2 stock items for this to fit: the thru-fender-wall plastic piece, and the fender's plastic sheet trim (~12"x18"). I removed the entire plastic "sheet" because of my first set-up, but I believe with the my final set-up, I could have just trimmed a few items where the spectre tubing would make it bulge out. I did have to use zip ties to pull the spectre tight away from the over sized tires where the spectre duct turns forward and heads to the scoop. It is also tied up where it turns, unfortunately about 90 degrees again, thru the metal fender wall and into the stock air box.

I have not measured the air temperature, but I can check my scangauge. I just didnot measure any baselines before hand. It does have more pep at highway speeds; mine is the V6. I use the Amsoil's filter in the stock box, and it does not get dirty at all. I have not had any water issues, but I need to make it a point to check it after driving thru some puddles. And I lifted just the front to level the stance with Icon's 2.5" coil-overs.

[Hi Volt]

Good work Guys,

Nice to see the idea is alive and well.


Jeff

279,000 miles and running strong.

[toyotalover79]

Well it has been a while since the mod, 1200 miles and one drag race. Obseravtions on my truck; first, this does pick up bottom end performance, no question. Top end performance is a given with more air flow, highway travel rocks ! Extended highway mileage seems up, city seems the same.
I regularily drag race this truck at the track and have logged over 200 passes. I have a good feel for what the truck will do and can usually make consistant passes within 1 or 2 hundreths of a second. I just came back from a race this last weekend and have calculated the improvements. I was able to find records of passes made in very similar weather conditions ( temp, humidity, barometric, all used to calculate corrected altitude ) and came up with the following repeatable numbers. My 60' times dropped by a close average of .147 seconds ( quite substancial) and the ET picked up by an average of 0.41 seconds with a trap speed improvement of 1.48 MPH. All these numbers were averaged over 4 passes and did not vary on any pass more than 5 %. The average corrected altitude was 1800', so more would be present at sea level air conditions. For those who do not race, these numbers represent bottom end improvements as seen by the 60' et's while the higher trap speed represents top end gains. The overall ET gains are a combination of bottom end and some top end gains. Using a HP factoring program, it is calculated that a gain of 17 HP was required for what was recorded. I admit the numbers sound large, but on a cool evening slamming the throttle at 40 MPH will set my head firmly into the headrest ( never felt it that much before). Now keep in mind that these improvements happened on my truck as I definately needed more air from my measurements. On another note, I am not really heavily modified either, K&N drop in, headers and a 2 1/2" single output cat back exhaust. I am confident that the exhaust modifcations caused more scavenging of the cylinders and the resultant undesired WOT engine vacuum. Those trucks with bigger exhaust may require even more air than I do ( there will finally be an upper limit ), as well as any SC vehicle will definately benefit from less air restriction. The CAI systems provide more air, but as some have seen effect the MAF in a negative way, this mod definately does not mess up the MAF. I used a 2" hose for more air, perhaps a larger one would have a bit more improvement ? however the vacuum gauge said it shouldn't. I may put in a second one for a test. It is really easy to go back to the factory restriction as well, just plug the hose! This will allow back and forth tests to really see the difference and discount any other possible effects. This turned out to be one of those rewarding mods that cost next to nothing ( less than a buck and a half per HP, wish I could spend a couple of hundred this way ! but in all reality this is most likely the practical limit for this mod.)

Amazing. You sir are quality. Every little detail noted, excellent. Keep up the amazing work.