I am coming to this discussion a bit late as I only recently began posting on AFM. Also, I used to work on the cars I had as a teenager in the late '80s, but they were all old cars from the '70s and nothing like trying to work on a car from today. I know very little about more modern engines. That is why I read posts on these forums, to learn. My question relates a bit to the 'ram air' vs. 'CAI' discussion, and a bit to something a little different.
My '02 GT is rated at 260hp stock with a SOHC engine. A mechanic I talked to at a performance shop guessed that the minor mods we can see (listed in my sig), which were done before I bought the car, would probably give me a gain of around 40hp, which would put me up around 300hp. From what I have read, the '03 Mach 1 put out about 305hp stock. It would seem to me that if a CAI and exhaust system could put a SOHC engine up to around 300hp then why wouldn't the Mach 1 with a functional hood scoop and the a DOHC engine make more than 305hp? Is the mechanic over-estimating my hp gains or are the articles I have read underestimating the Mach 1? Or is the hood scoop on the Mach 1 not quite as functional as claimed and are all the extra horses from the DOHC? Is the real attraction of the Mach 1 just that it is a Mach 1? If so, I could understand that - the shaker hood looked great in the early 70s and still looks great. Also, I wonder how the 'at the tires' horsepower would differ between mine and the Mach 1. I apologize in advance for my lack of knowledge and if I went a bit off topic.
All good questions, JB02GT. My guesstimate on gain from your current mods more like 20hp tops. Love to see dyno test on Mach I w/the stock intake setup and then just a decent CAI intended for a N/A Cobra, guessing the current 'shaker' is more restrictive than the Cobra intake would be. Looks nice though and car has great heritage, and, yes, the 4-valve motors rock. Would guess you're still in the 240-245rwhp area. Not to worry, car can be made to run; all depends on wallet/goals.
Can touch base w/Mach I guys over here: http://www.mach1registry.org/forums/
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I'm back - 2002 GT Convertible, auto: Continental Extreme Contacts, KYB GR-2 shocks/struts, Ford Racing "G" springs, Maximum Motorsports camber plates, 3 pc grill delete, Mach I chin spoiler.
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
Thanks for the info, guys. Probably no other engine mods for me in the near future. I've been driving for about seventeen years now but have no real drag racing experience. Being my daily driver, I don't want to take it to the drag strip and do something stupid due to inexperience and then be out of a way to get to work. Maybe after some time on AFM I can learn enough to hit the strip without doing something stupid, but right now any extra cash will probably go to appearance mods. I plan to do most of the grunt work for those myself and only want to do things which can be fairly easily returned to stock. Right now, I am most interested in finding out if the computer has the factory settings or if it has been Diablo tuned, etc. As for Mach 1s, not to get too far off topic but I mentioned in another forum that a local classic car dealer has a '70 Mach 1 with a 351 on his lot right now. It is black on yellow. I stopped in the other day when they were closed to get a closer look and man is that thing gorgeous - the shaker hood really does complete the look regardless of functionality or lack thereof. Of course, he wants almost exactly as much for it as I paid for my '02, so I won't be whipping out the checkbook or anything (but I might if I had the cash). Now I've got to get back there when he is open to see the Shelbys (yes, more than one) he has in his showroom. Maybe he will even let me take some pics to post on AFM if anyone is interested.
...but right now any extra cash will probably go to appearance mods.
Did I really say that? Guess that was before I was taken over by 'the spirit of the Mustang.' Now, I have changed my mind. Still want to do the appearance stuff, but 'go-fast' stuff is now on the list, too. Nothing really extreme, but I would like to eventually have a N/A setup on my daily driver that will perform on a comparable level with, or maybe even a little better than, the 05/06 GTs - without destroying my gas mileage. Not that this is the appropriate place to ask how to do that, just letting everyone know I had gotten over my 'temporary insanity'.
quick question- does anyone have a copy of the original article that started this thread- its not there anymore...I am waiting for my 69 cougar eliminator scoop , and this thread has really got me wondering...I intend to make scoop functional , dumping into original airbox(excess blowing back into fenderwell) not for ram-iar, but for true outside air...to me the CAI units out there seem like they would still get a little underhood heating(insulating ductwork from scoop will be needed or its same thing) and a scoop forcing excessive air into the airbox might actually help cool the airbox itself...
My want is not necessarily more power, but the hope of even better MPG. One guy in here put a shaker on with no mods and said his highway mpg went from 26 to 30 with no other changes- figured worth a shot...maybe some insulation on the factory intake tube, and some vents at the plastic cowl center to pull some air from underhood while cooling the top of the engine a bit might work...
Question to throw out there- to me adding a plenum cover would result in increased heating of the intake, costing hp...any thoughts on this?
Would like to see the original article as to why ram-air cant work though if someone copied it...
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Our Blue Fords:
2007 V6 Vista Blue/Auto/Coupe/Pony (Wife's car)
2006 GT Vista Blue/Stick/Coupe (Mine)
1969 Fastback Acapulco Blue (in pieces since '84)
1965 Galaxie 500 LTD Caspian Blue/White
quick question- does anyone have a copy of the original article that started this thread- its not there anymore...I am waiting for my 69 cougar eliminator scoop , and this thread has really got me wondering...I intend to make scoop functional , dumping into original airbox(excess blowing back into fenderwell) not for ram-iar, but for true outside air...to me the CAI units out there seem like they would still get a little underhood heating(insulating ductwork from scoop will be needed or its same thing) and a scoop forcing excessive air into the airbox might actually help cool the airbox itself...
My want is not necessarily more power, but the hope of even better MPG. One guy in here put a shaker on with no mods and said his highway mpg went from 26 to 30 with no other changes- figured worth a shot...maybe some insulation on the factory intake tube, and some vents at the plastic cowl center to pull some air from underhood while cooling the top of the engine a bit might work...
Question to throw out there- to me adding a plenum cover would result in increased heating of the intake, costing hp...any thoughts on this?
Would like to see the original article as to why ram-air cant work though if someone copied it...
For what it's worth, I have seen claims that while cold air gives better hp gains, warm air actually gives better fuel economy because it supposedly helps burn fuel more thoroughly and effeciently. I remember reading on a website dedicated to improving fuel economy where one guy talked about getting better gas mileage by rigging up a system that purposefully sent warm air into the intake. Could be complete hogwash, though.
"Intake Heat (http://cars.rasoenterprises.com/Carbs-IntakeHeat.htm) - Override your car's air intake system to always use hot air. On some cars this can be as simple as jamming the hot air flapper valve open. Yes, cold air is denser and has more oxygen for racing, but hot air helps fuel vaporization and ignition for economy"
All I know is the ram air systems on my 2005 MustanGT and Focus (non PZEV 2.0L) works. Once you lick the lean fuel mixture problems, mid and high engine revolution performance improvement is noticeable. I can measure a pound or two of positive intake manifold pressure...especially on the Focus. Downside is more frequent air filter replacements and lower fuel economy. But it's worth it.
Where are you measuring this positive pressure and at what speed?
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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
Where are you measuring this positive pressure and at what speed?
Manifold air pressure is "T"d to an Autometer Vacuum Meter for constant viewing pleasure. AutoXray 5000 for verification and computer analysis. I have measured a 20% increase of positive air pressure with the TPS (throttle position sensor) open beyond 66%. 10% at cold idle (TPS open 20%). Seems the faster you go the more HP's you get...up to a point. The K&N and plumbing will only allow so much through. 90mm MAF and Throttle body did yield improvements.
Lean trouble codes from HO2S front sensor due to the Intake Air Temperature sensor (IATS) not measuring correctly. Remember, it is inside the engine compartment where it is 3-10 degrees or more warmer than outside air. The faster the ride, the colder the air, the bigger the error. 2005 MustanGT and Focus air intakes are from the least turbulent part of a moving vehicle...front wheel wells.
In fact, the Focus air inlet is facing backwards towards the rear. That's why ram air is more noticable on my four banger.
Our Mustangs are simular. I am using the OEM air tube because aluminum tubes retain more heat before launching. Could not air inlet thru the front grille because the intercooler radiator is there and would not air inlet under the front chassis. So, I modified the air box to allow a 4" ABS pipe to poke thru the front fender. My scoop is from a 2001 Camaro mounted vertically on the fender. For competition the scoop screws off and I push on a 4" 90 degree ABS joint that is cut and channeled. Ugly as sin, but I get a pound or two extra air with the joint sticking out and away from the fender.
PCM's and 124 MPH engine cutoffs are a *****...but I got getarounds for that.
That sounds like a lot of work for 1-2psi at higher speeds. How much power did you gain with that setup on the Mustang?
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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
Don't know. Mongo only pawn in game of life
Hard to measure ram-air Dyno horsepower increase with a stationary vehicle in the bay. The external cold air intake system feeds a superrrchargerrr as well. Cheep Speed. The centrifigal accelorometer in my butt tells my brain I'm goin' faster.
More noticeable acceleration with the Focus Duratec 20 2.0 Liter. We have garbage gas on the left coast, but the 10-12% drop in MPH may mean 10-12% pop in performance. Remember, a combustion engine is nothing more than a verrry warrrm vacuum pump.
Here is a piece I pulled off of Covette forums. It is a compiliation of "Ram Air" stuff and airbox resonance information. It's a good read. The theory would apply to any car I would think. As with anything else, read and compare.
Cheers.
Quote:
Ram Air - Myth or Truth?
Marketers just can't resist it. Ram air! The words themselves summon up images of rushing wild beasts, or of secret military aircraft operating on futuristic principles.
Unfortunately, on most perofrmance cars, ram-air is as functional as tail fins were on cars of the ’60s.
What is it? Ram air just means using a forward-facing air intake to gain some extra intake pressure. We have all, as children, felt the pressure of moving air on our hands when we held them out the window of the family car. When moving air is brought smoothly to rest, the energy of its motion is converted into pressure. Motorcycles went through a "ram-air" period in the early 1990s, during which street bikes were equipped with the forward-facing "rocket-launcher" engine air intakes seen on many road-racing machines.
While it's appealing to imagine the forward velocity of a car being converted into free supercharge, the actual air pressure gain is extremely small at normal speeds. For example, at 150 mph, the pressure gain when air is efficiently brought to rest is 2.75 percent. Because this is a dynamic effect, it is proportional to the square of the air velocity. At a more realizable automobile speed of 75 mph, the effect (again with 100 percent efficient conversion of velocity into pressure) will be only one-quarter as great — that is, just under seven-tenths of one percent.
In fact, velocity energy is not converted into pressure at 100 percent efficiency. A figure of 75 percent efficiency is usual, which reduces our notional ram-air gain at 75 mph to one-half of one percent.
Therefore, at normal speeds, ram air is a myth. However, something much more interesting lies behind it, ignored by the advertiser's busy pen. That something is airbox resonance.
In order to implement ram air, the carburetors or throttle-bodies of our engine must seal to an airbox whose volume is large enough that the intake cycle of one cylinder cannot pull its internal pressure down significantly. Box volume is typically 10-20 times the engine's displacement. Then the forward-facing air intake is connected to the box. When this assembly is tested on the dyno — even without an external fan to simulate the high-speed rush of air past the intake — it is discovered that the engine's torque curve is greatly altered, with new peaks and hollows.
Why? The answer is airbox resonance. If you hold the mouth of an empty bottle near your open mouth as you loudly hum scales, you find that at certain “hum frequencies” the bottle reinforces your humming, which becomes louder. What is happening is that the springy compressibility of the air in the bottle is bouncing the slug of air in the bottle's neck back and forth at a particular frequency — higher if the bottle is small, lower if it is larger. Your humming is driving a rapid plus-and-minus variation of the air pressure inside the bottle.
The same thing happens inside a resonant airbox. The volume of air in the box is the “spring” in this kind of oscillator. The mass of air in the box's intake pipe is what oscillates. The “humming” that drives the oscillation is the rapid succession of suction pulses at the carb or throttle-body intakes. If the volume of the airbox and the dimensions of the intake pipe(s) are correctly chosen, the airbox can be made to resonate very strongly, in step with the engine's suction pulses. The result, when this is done correctly, is that the engine takes air from the box only during the high-pressure part of its cycle, while the box refills from atmosphere through its intake between engine suction pulses. This produces a useful gain in torque.
Using this idea, motorcycle engines have been able to realize torque increases, in particular speed ranges, of 10-15 percent. In race engines, it is usual to tune the airbox to resonate at peak-power rpm to increase top speed. For production engines, it is often more useful to tune the box resonance to fill in what would otherwise be a flat-spot in the torque curve, resulting in smoother power and improved acceleration.
Early resonant airbox systems used long intake pipes that terminated in forward-facing intakes. More recent designs do not connect the ram-air pipe to the box at all, but terminate it near the airbox entry. The actual entry pipe is a short piece of tubing with bellmouths on both ends. This is done because (a) the potential gain from actual ram air is too small to worry about, and (b) it's easier to tune the airbox with a short tube.
Where vehicle speeds are very high, gains from ram air are significant. This was discovered by Rolls-Royce in the late 1920s as the company developed its R Schneider Trophy air racing engine. At speeds above 300 mph, it was noticed that the R’s fuel mixture leaned out enough to cause backfiring. When the mixture was corrected for ram-air pressure gain, the engineers realized they had a "free" source of power. At 350 mph the gain from ram air is almost 15 percent. Similar mixture correction is necessary when ram air is used on drag-race and Bonneville cars and bikes.
Intuition suggests that a forward-facing intake made in the form of a funnel, large end foremost, should somehow multiply the pressure of the air, resulting in a much larger pressure gain at the small end. Sadly, intuition is wrong. In order to convert velocity energy into pressure, the air has to be slowed down, and this requires a duct that widens rather than narrows. Next time you fly on a commercial airliner, note that its engine intakes widen as the airflow approaches the compressor face. Such widening passages are called diffusers, and they are universally used in the conversion of velocity into pressure.
Language often plays tricks on us — especially when language is used by product advertisers. "Ram air" sounds much more appealing than "resonant airbox." Nevertheless, it is airbox resonance that actually generates a significant power gain.
-Ram Air a myth? = NO
-Does it work on a road car = NO
-At 150mhp there is next to no gain.
-Significant gains arn't seen until 300mph+
-The air box is the key, not the ducting.
-When buying a CAI/induction kit look for the one that uses air box resonance
Edit: Additional Reading
Intake temperature is a whole different ball game.
The simple rule is:
'Cool for power (maximum charge density), hot for economy (minimum charge density to reduce losses due to throttling).'
Although in many cars the under bonnent temperatures are no where near as bad as many people beleive. This refers to a 5.3 liter Jguar XJS V12. So a big engine in a small engine bay.
The under-bonnet air temperature at idle can easily get up around 70 C but the faster the car goes the lower the air temperature falls - simply because the radiator is passing its heat to a much larger quantity of air per second - so at 80 mph. the engine is breathing air at around 45 C. That's still a bit higher than the ideal but not nearly so bad as many people think. Obviously the standard arrangement helps to maximise economy in moderate speed urban cruise without compromising top end power too much.
In setups that duct cool air from outside. The power gains from such a system are almost certainly attributed to the filter, and less restritive intake (meaning quite simply a bigger opening), and a form of air box resonance coupled with a 'cool air intake' from outside the engine bay. Sadly even at very high speeds (well over 100mph) I doubt that it has any form of 'Ram Air' effect. If you reconfigured the system to take air from the inside of a wheel arch it would produce the same results as having the intake ducts at the front of the car. The source of the air, not the location of the ducts is the important factor.
Remember the only way to get a greater volume of air into the engine is to compress it. This is what turbo and superchargers do. An air intake scoop either on the front of a car or on the bonnet will not compress the air at any speed most people are likely to travel at.
Taking the airbox resonance theory futher with the intake manifold itself by optimising the length and entry profile into each of the tracts to better exploit induced harmonic resonances in the air as it flows towards the cylinder. Any tube containing air can be made to resonate at certain critical frequencies in the manner of an organ pipe. Such is the case with the inlet tracts of an engine and if the natural resonance frequencies can be matched to the engine speed then a mild supercharging effect can be induced. Get it wrong and the reverse will apply, resulting in a loss of performance.
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'97 GT with 80mm C&L MAF, C<rue-Flow CAI, MAC 70mm TB, Superchip, 180 thermo, B&M Ripper, King Cobra Clutch, FRPP aluminum quad/adj cable, MAC O/R H pipe, MIL's, Flows, Granatelli Solid control arms, FRPP 4.10's, FRPP aluminum driveshaft, Fidanza aluminum flywheel, FRPP 9mm wires, TMD aluminum U/D pulleys, Steeda full length SFC's (welded in), and 17" polished aluminum Cobra wheels with Nitto 555 Extremes, Kenwood/Alpine sound. Waiting for install: PI intake.
