Intake or Exhaust?
05-25-06, 06:38 AM
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Intake or Exhaust?
My father has an '04 Gx470 and asked me to find a way for a little more hp and see if we can up the mpg. Has any one tried this as I know it's not a racing car? So any suggestions would be great. 
05-25-06, 08:41 AM
#2
Super Moderator
The exhaust will give you more than an intake (unless you plan to do forced induction). Plus, intakes need to be well designed to give the type of power one can get off of an exhaust.
A few ways to do it on an exhaust (legally as far as I know in the U.S. (I am a gringo)).
-the easiest is to get a direct flow muffler as opposed to that angled in/out muffler and that will give you some hps immediately and will increase MPG
Now, depending on how much of a lead foot he has:
-widen the width of the exhaust .5 to 1 inch after the last catalytic converter or resonator, requires different muffler with wider width
-after the cat or resonator, do a y-pipe to split mufflers with stock pipe or even wider pipe, if you did it after the cat, you may need an extra resonator depending on the sound and will need different mufflers if you use wider pipe
-do a y-pipe after the resonator with twin pipes going out of a muffler with twin inlets/outlets (that is how I have it on my RX)
This actually may have the opposite effect on MPG if he has a heavy foot.
A few ways to do it on an exhaust (legally as far as I know in the U.S. (I am a gringo)).
-the easiest is to get a direct flow muffler as opposed to that angled in/out muffler and that will give you some hps immediately and will increase MPG
Now, depending on how much of a lead foot he has:
-widen the width of the exhaust .5 to 1 inch after the last catalytic converter or resonator, requires different muffler with wider width
-after the cat or resonator, do a y-pipe to split mufflers with stock pipe or even wider pipe, if you did it after the cat, you may need an extra resonator depending on the sound and will need different mufflers if you use wider pipe
-do a y-pipe after the resonator with twin pipes going out of a muffler with twin inlets/outlets (that is how I have it on my RX)
This actually may have the opposite effect on MPG if he has a heavy foot.
05-30-06, 06:54 AM
#3
Is there any real-world proof (before and after mileage tests, dyno tests?) that this will have the claimed effects, or are these just assumptions?
Originally Posted by Lexmex
-the easiest is to get a direct flow muffler as opposed to that angled in/out muffler and that will give you some hps immediately and will increase MPG
Now, depending on how much of a lead foot he has:
-widen the width of the exhaust .5 to 1 inch after the last catalytic converter or resonator, requires different muffler with wider width
-after the cat or resonator, do a y-pipe to split mufflers with stock pipe or even wider pipe, if you did it after the cat, you may need an extra resonator depending on the sound and will need different mufflers if you use wider pipe
-do a y-pipe after the resonator with twin pipes going out of a muffler with twin inlets/outlets (that is how I have it on my RX)
This actually may have the opposite effect on MPG if he has a heavy foot.
Now, depending on how much of a lead foot he has:
-widen the width of the exhaust .5 to 1 inch after the last catalytic converter or resonator, requires different muffler with wider width
-after the cat or resonator, do a y-pipe to split mufflers with stock pipe or even wider pipe, if you did it after the cat, you may need an extra resonator depending on the sound and will need different mufflers if you use wider pipe
-do a y-pipe after the resonator with twin pipes going out of a muffler with twin inlets/outlets (that is how I have it on my RX)
This actually may have the opposite effect on MPG if he has a heavy foot.
05-30-06, 01:52 PM
#4
Super Moderator
If you type muffler and "more mpg" in google you should find tons of threads on the relationship between a direct flow or straight thru muffler, mpg and even hp.
05-31-06, 09:21 AM
#6
LMAO How about the "turbonator" or any number of other BS items that improve Hp and fuel mileage by 40%? Do you recommend those just because some marketing guy is out there on the interweb making claims, or because someone has been suckered by the placebo effect? My 30+ years of experience in modifying and tuning cars has taught me that there are lots of people who will say, and even believe, any goofy BS that you can imagine. If increasing MPG were so simple as a freer-flowing muffler, then Toyota and all the others would have done that years ago because MPG ratings are so important.
Much more telling are the magazine tests where they dyno before-and-after exhaust and air filter mods, and other changes. Much of the time, there is about 2 or 3 HP difference in exhaust and air filter mods, and it's almost always the increases are at Wide Open Throttle (WOT) and at the upper extremes of the RPM range. Under these conditions you will be getting about 1 MPG anyway, so it doesn't matter as far as MPG. Re: HP increase, 5 - 10 HP isn't even detectable in a vehicle with 235+ HP, so that's all in the owner's head when he raves about how much stronger the vehicle feels.
Do you recommend those just because some marketing guy is out there on the interweb making claims, or because someone has been suckered by the placebo effect? My 30+ years of experience in modifying and tuning cars has taught me that there are lots of people who will say, and even believe, any goofy BS that you can imagine. If increasing MPG were so simple as a freer-flowing muffler, then Toyota and all the others would have done that years ago because MPG ratings are so important. Much more telling are the magazine tests where they dyno before-and-after exhaust and air filter mods, and other changes. Much of the time, there is about 2 or 3 HP difference in exhaust and air filter mods, and it's almost always the increases are at Wide Open Throttle (WOT) and at the upper extremes of the RPM range. Under these conditions you will be getting about 1 MPG anyway, so it doesn't matter as far as MPG. Re: HP increase, 5 - 10 HP isn't even detectable in a vehicle with 235+ HP, so that's all in the owner's head when he raves about how much stronger the vehicle feels.
Originally Posted by Lexmex
If you type muffler and "more mpg" in google you should find tons of threads on the relationship between a direct flow or straight thru muffler, mpg and even hp.
Last edited by I6turbo; 05-31-06 at 09:30 AM.
05-31-06, 12:22 PM
#7
Super Moderator
Originally Posted by I6turbo
LMAO How about the "turbonator" or any number of other BS items that improve Hp and fuel mileage by 40%? Do you recommend those just because some marketing guy is out there on the interweb making claims, or because someone has been suckered by the placebo effect? My 30+ years of experience in modifying and tuning cars has taught me that there are lots of people who will say, and even believe, any goofy BS that you can imagine. If increasing MPG were so simple as a freer-flowing muffler, then Toyota and all the others would have done that years ago because MPG ratings are so important.
Much more telling are the magazine tests where they dyno before-and-after exhaust and air filter mods, and other changes. Much of the time, there is about 2 or 3 HP difference in exhaust and air filter mods, and it's almost always the increases are at Wide Open Throttle (WOT) and at the upper extremes of the RPM range. Under these conditions you will be getting about 1 MPG anyway, so it doesn't matter as far as MPG. Re: HP increase, 5 - 10 HP isn't even detectable in a vehicle with 235+ HP, so that's all in the owner's head when he raves about how much stronger the vehicle feels.
Do you recommend those just because some marketing guy is out there on the interweb making claims, or because someone has been suckered by the placebo effect? My 30+ years of experience in modifying and tuning cars has taught me that there are lots of people who will say, and even believe, any goofy BS that you can imagine. If increasing MPG were so simple as a freer-flowing muffler, then Toyota and all the others would have done that years ago because MPG ratings are so important. Much more telling are the magazine tests where they dyno before-and-after exhaust and air filter mods, and other changes. Much of the time, there is about 2 or 3 HP difference in exhaust and air filter mods, and it's almost always the increases are at Wide Open Throttle (WOT) and at the upper extremes of the RPM range. Under these conditions you will be getting about 1 MPG anyway, so it doesn't matter as far as MPG. Re: HP increase, 5 - 10 HP isn't even detectable in a vehicle with 235+ HP, so that's all in the owner's head when he raves about how much stronger the vehicle feels.
OK. I like your post.
More hp and more mpg thing by removing restriction at the end of the exhaust isn't rocket science to me anymore. How you go about doing it will determine your mpg and hp and that is why I made no quantitiative analysis since it all depends under this topic. The reason I said direct flow muffler is that we could just remove the the muffler, but that might cause unwanted attention on the road.
Regarding intakes, I don't know beyond forced induction anyway that one could get close to exhaust mods in terms of mpg or hp, though I have tried with a ram air system on my vehicle, but everytime I after I take my RX300 to the track, the exhaust mods pan out better than the air intake. In addition, the intakes are susceptible to heat and altitude changes (very much in my case), whereas the exhaust is much more consistent. I don't doubt modern science could deliver a great intake system. And again, we could talk about other modifications, but the topic was exhaust or intake.
The turbonator is crap (and I have discussed this one before) and is no more than an obstruction in the pipe. I understand what exactly they are claiming, but that is why you have a hose or pipe to flow the air along, you don't need much more. One of the things I have found a little less comical is this eram electric superchager. I don't doubt you can throw air into an engine and increase power, but like any other mod on a car is it really worth it for the $300 to $500 USD, depending on the system. However, one of the ways this is shown to work on their site is to put in the intake tract and it only works on WOT, and I supposed it then becomes a turbonator when not in use. You decide on something like that though a few people actually want me to test one of these things on my RX300.
In addition, the only real way I have of testing something here and I have been doing it for almost 2 years with my RX300 is to haul it down to the track as I do every Friday and Saturday night making notes about air pressure, air temperature and humidity and watch the times.
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05-31-06, 01:51 PM
#9
Originally Posted by I6turbo
My 30+ years of experience in modifying and tuning cars has taught me that there are lots of people who will say, and even believe, any goofy BS that you can imagine. If increasing MPG were so simple as a freer-flowing muffler, then Toyota and all the others would have done that years ago because MPG ratings are so important. :
Hybrid idea has been around for a long time to increase mpg, but Honda and Toyota introduce it only in recent models to the U.S. market because there was not enough demand in the past. It is important for them to have high mpg for every car, but not at the expense of offering a state-of-the-art feature/design that sells poorly.
Last edited by TunedRX300; 05-31-06 at 03:36 PM.
06-01-06, 05:26 AM
#11
Lexus Test Driver
I don't think the question was, "How do I get a ton more HP?" It was about how to get a little more HP the easiest way. Appreciable or not, it is via exhaust.
Yes, you will not see much of a difference, but you do get an increase even if it is not noticed. IF you tweak and tweak here and there, you can eventually add a great amount of HP. Now; what you do with that or if it is even needed is up to the consumer or modder.
CV
Yes, you will not see much of a difference, but you do get an increase even if it is not noticed. IF you tweak and tweak here and there, you can eventually add a great amount of HP. Now; what you do with that or if it is even needed is up to the consumer or modder.
CV
06-01-06, 07:29 AM
#12
When it comes to gas mileage, they don't make many tradeoffs unless it is for the purpose of meeting emissions standards (though these usually compliment each other, and don't require tradeoffs). Therefore, I disagree with your claim that they aren't interested in making the most efficient car. Fuel mileage sells cars, and selling cars is what they are interested in doing.
Power? Yes, they will make some tradeoffs for power in order to acheive better MPG, less NVH, or better durability. However, adding an aftermarket muffler doesn't by any means guarantee more power just because the seller makes that claim and it's been repeated on the internet 50000 times until it's believed by everyone who doesn't know better. In some cases on modern vehicles a full aftermarket exhaust system can acutally reduce power and mileage if the engine control module isn't reprogramed (generally not possible on Toyotas) or fooled (via piggy-back units) to compensate for the new-found airflow (in the event that the new system supports better airflow than the factory system).
Power? Yes, they will make some tradeoffs for power in order to acheive better MPG, less NVH, or better durability. However, adding an aftermarket muffler doesn't by any means guarantee more power just because the seller makes that claim and it's been repeated on the internet 50000 times until it's believed by everyone who doesn't know better. In some cases on modern vehicles a full aftermarket exhaust system can acutally reduce power and mileage if the engine control module isn't reprogramed (generally not possible on Toyotas) or fooled (via piggy-back units) to compensate for the new-found airflow (in the event that the new system supports better airflow than the factory system).
Originally Posted by TunedRX300
It is incorrect to assume that Toyota or any automaker must have the best design. In fact, it is their best interests to make tradeoffs, not the most effecient or powerful car. Toyota offers features or designs so they can make maximum amount of $, not "relentless pursue of perfection" that is advertised in Lexus' commercials.
Hybrid idea has been around for a long time to increase mpg, but Honda and Toyota introduce it only in recent models to the U.S. market because there was not enough demand in the past. It is important for them to have high mpg for every car, but not at the expense of offering a state-of-the-art feature/design that sells poorly.
Hybrid idea has been around for a long time to increase mpg, but Honda and Toyota introduce it only in recent models to the U.S. market because there was not enough demand in the past. It is important for them to have high mpg for every car, but not at the expense of offering a state-of-the-art feature/design that sells poorly.
06-01-06, 10:34 AM
#14
Originally Posted by The G Man
Can you imagine Lexus trying to sell the GX as a luxury SUV with a high flow muffler that sounds like a Harley?
06-01-06, 10:53 AM
#15
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Originally Posted by The G Man
Can you imagine Lexus trying to sell the GX as a luxury SUV with a high flow muffler that sounds like a Harley?
On my 99 Grand Cherokee with a V8, I put on a Gibson exhuast. My measurable mpg went up about 8%. Supposedly, dyno testing from other owners showed about 20 HP/T improvement over stock, but I never tested mine. And it wasn't much louder, just deeper.