alright, i know there are basically two types of intakes for the foxes, first the one that the intake filter sits inside the firewell, second the other were the filter sits right by the engine..... well me question, which one is better, the filter inside the firewell doesn't get as much hot air, as oppose to the filter sitting by the engine, but the filter inside the tirewell is kinda small compared to the other one.....so which one produces more hp. the larger filter, or the smaller one inside the tire well that gets fresher air???
You asked an excellent question, and the answer is a quandry as to the answer. Here is your answer as best I can put it....
If you can't get it in you can' tmake power out of it.
Now, here is two trains of thought on that very subject. If the filter that is in the engine bay close to the intake you woudl need more surface area open to intake air. If the filter is in the tirewell then you are pulling cooler denser air, and the biggest filter you can get in that area will make more power than a smaller one. Which one will make more power? Well there are several ways to find this out, and they both require a dyno, and the same car.
I have noted in other sections of this forum that I am a chevy guy. I am also a carb guy. So thsi question can be answered by me where it will quantify a good answer that will work in both worlds.
I run cowl induction style hoods on every hotrod car I ever built. I also went so far as to but on the tallest, free-est flowing filter I could find (K&N is simply the finest filter on the market for power). I also built aluminum boxes that sat on the filter base of the carb, and were sealed wil high density foam weatherstrip to the cowl area of the hood with as much clearance around the outside of the filter as I could manage (the width of the scoop section of the hood). The reason behind pulling form the cowl area is that the air flowing over the hood is obviously cooler than the air coming into the engine compartment.
Simply put, the place where you can pull the coolest air, and thelargest amount of it will make the most power.
Doing what I did with cowl hoods was worth 10 to 15hp over going the engine compartment intake route. That sounds huge, but when you are making over 500hp and you have an engine that will take every advantage of what you make avaiable to it, 10 to 15 is easy to get.....and a good filter helps that.
You asked an excellent question, and the answer is a quandry as to the answer. Here is your answer as best I can put it....
If you can't get it in you can' tmake power out of it.
Now, here is two trains of thought on that very subject. If the filter that is in the engine bay close to the intake you woudl need more surface area open to intake air. If the filter is in the tirewell then you are pulling cooler denser air, and the biggest filter you can get in that area will make more power than a smaller one. Which one will make more power? Well there are several ways to find this out, and they both require a dyno, and the same car.
I have noted in other sections of this forum that I am a chevy guy. I am also a carb guy. So thsi question can be answered by me where it will quantify a good answer that will work in both worlds.
I run cowl induction style hoods on every hotrod car I ever built. I also went so far as to but on the tallest, free-est flowing filter I could find (K&N is simply the finest filter on the market for power). I also built aluminum boxes that sat on the filter base of the carb, and were sealed wil high density foam weatherstrip to the cowl area of the hood with as much clearance around the outside of the filter as I could manage (the width of the scoop section of the hood). The reason behind pulling form the cowl area is that the air flowing over the hood is obviously cooler than the air coming into the engine compartment.
Simply put, the place where you can pull the coolest air, and thelargest amount of it will make the most power.
Doing what I did with cowl hoods was worth 10 to 15hp over going the engine compartment intake route. That sounds huge, but when you are making over 500hp and you have an engine that will take every advantage of what you make avaiable to it, 10 to 15 is easy to get.....and a good filter helps that.
Doc
Wow, well put, for a chevy guy
JK, lots of very useful info there, GJ
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1988 Mustang GT - 331, hand ported Twisted Wedge heads, TFS Stage 2 cam, R-Series intake, 1 3/4 long tubes, dual 3" exhaust, tko 600, Zex 100 shot, ect.
357 rwhp/ 361 rwtq on motor
428 rwhp/ 484 rwtq on 100 shot
12.48 @ 111 mph on motor (2200ft + elevation)
11.7 @ 120 mph on 100 shot (2200ft + elevation)
Regardless of what kind of engine you are dealing with, if you want to make big power numbers you have to be able to do three things.....get it in, squish hard and fire it off, and get it out. If you can do those three things you can make big power.
Cold air, regardless of source (wheelwell or cowl area), and large amounts of it will have your engine singing a tune that will make you grin really big......gauranteed.
I agree with just about everything Doc has said, well put actually. There's one misconception that has existed since time began for performance engine building. "Colder, denser aire makes more power". Well colder air does make more power, and it is denser. But the difference in the density does not make the difference. It's the fact that with colder air, you can run more timing advance. The magnitude of temperature change it would take to make a hill of beans difference as far as the O2 content of each Liter of air is somewhere in the 100F range. So unless you change your intake from sucking in 250F air to 150F (or lower) you're not making any more power because of the density difference, it's the timing advance that's doing it for you.
Also I have yet to see a CAI or cowl induction setup that is a restrictive intake. Most are incredibly free flowing. Just as Doc stated, if you can't get it in, you can't make power with it.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Like Blue said, the difference is in the 250 degree air (under the hood) as opposed to the outide air (wheelwell or cowl area).
Most of the aftermarket ignition systems have an add-on box that will allow you to play with the timing a bit. Be careful as you can just as easily blow up your stuff if you are making huge changes!!!!!
We have gone so far in the carbed world as to running an ice can and a coil of fule line inside the can and cooling the fule off with dry ice or cold ice water to make up the difference.
Look at what you have intake wise, and fine the least restrictive way to get cooler air (outside the engine compartment) into that intake. Can you do it with a cowl setup, or will you have to run a big tube out to the fenderwell area?
Here's a question: I know little about how turbos work (because I don't like them)
So, if cold air makes for the best power, How does running hot exhaust back through the engine make power? This is probably a stupid question that will likley
have a simple answer, but I appreciate the info.
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Currently sans Mustang
Gone but not forgotten: '83 Charcoal GT 5 spd,
'89 Black/Titanium GT 5 spd, '90 Black LX Hatch 5 spd, ...
Turbo's do not actually pump the exhaust back through the motor, if that is what you are saying, if not sorry for my confused mind. But anyways, the exhaust in a turbo system is used to spin a turbine which turns an air pump, that pumps air coming from a filter to the motor. They do pick up lots of heat because of the exhaust being in the same area as the incoming air, but that is why they use an intercooler to cool down the air as much as possible before it goes into the motor.
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1988 Mustang GT - 331, hand ported Twisted Wedge heads, TFS Stage 2 cam, R-Series intake, 1 3/4 long tubes, dual 3" exhaust, tko 600, Zex 100 shot, ect.
357 rwhp/ 361 rwtq on motor
428 rwhp/ 484 rwtq on 100 shot
12.48 @ 111 mph on motor (2200ft + elevation)
11.7 @ 120 mph on 100 shot (2200ft + elevation)
Matt was a bit more generic than I on the subject of turbos.
Correctly a turbo is simply a turbine that forces more air through the induction system....like a blower.
The intercooler is simply an air to air heat exchanger. It works liek a radiator without the fluid. The fluid in this case woudl be intake air that is being passed along the system.
Turbos are very cool, and work very well. They can be expensive, and can be trouble if the engine is not built around the turbo. If you want to run one I suggest you pick up a few books on the subject of turbos, and plan to do alot of reading and spend a chunk of ching on the unit you intend to use. Turbos are not cheap, but if the engine is built to work well with one you will love the power difference a forced induction system (turbo) can offer.
Matt was a bit more generic than I on the subject of turbos.
Correctly a turbo is simply a turbine that forces more air through the induction system....like a blower.
The intercooler is simply an air to air heat exchanger. It works liek a radiator without the fluid. The fluid in this case woudl be intake air that is being passed along the system.
Turbos are very cool, and work very well. They can be expensive, and can be trouble if the engine is not built around the turbo. If you want to run one I suggest you pick up a few books on the subject of turbos, and plan to do alot of reading and spend a chunk of ching on the unit you intend to use. Turbos are not cheap, but if the engine is built to work well with one you will love the power difference a forced induction system (turbo) can offer.
Doc
This man knows his hip-hop
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1988 Mustang GT - 331, hand ported Twisted Wedge heads, TFS Stage 2 cam, R-Series intake, 1 3/4 long tubes, dual 3" exhaust, tko 600, Zex 100 shot, ect.
357 rwhp/ 361 rwtq on motor
428 rwhp/ 484 rwtq on 100 shot
12.48 @ 111 mph on motor (2200ft + elevation)
11.7 @ 120 mph on 100 shot (2200ft + elevation)
I am worse than tim Allen about making more power, and doing it on the cheap is that much better for me!
Turbos and superchagers are fun, and can make big power gains, but you better know what you are doing designing the engine. There is nothing worse than dumping a wad of cash in an engine to watch it go to pieces the first time you really stomp on it.
I build most of my stuff fairly conservative, and am very careful about how I put things together. Good piece of advice.....learn some machine work,a nd how to use the fine pieces of measuring equipment available to a machinist. Then learn the machines. You can do great things with little equipment if you know how to use it and what you need to do.
Grab every book you can on the subject of engine building and design and then add to that all of the carb and EFI books (I have been reading up on EFI stuff for some time). then add to the library some more and read up on Turbos and supercharging. Then learn to do the math involved in the paper planning stage.
I build my engines on paper before I buy the first part. Considering I have been building my own engines since the 80's (I am not telling you how old I am....or am I), I have learned alot the hard way. It is devastating to watch something you have put your heart into go to mush the first time you romp on it.....trust me...will make a grown man cry......
I love eninges, and old cars. I love racing, and riding around in something that will rip the front wheels off the ground when I jump the throttle and clutch.....I hate eating my hard earned money when I did somethign stupid when I was assembling the pieces.....it really sux.....
Build for power, but overengineer the support system of your engine and you will have a long lived fun machine.
a intake question that actually got me thinking 
. But anyways, the exhaust in a turbo system is used to spin a turbine which turns an air pump, that pumps air coming from a filter to the motor. They do pick up lots of heat because of the exhaust being in the same area as the incoming air, but that is why they use an intercooler to cool down the air as much as possible before it goes into the motor.
