Full Version: Thrott Body Bypass
Seriously, it was a pain in the rear-end. I think someone out here said, "oh yea just rip the old tube out and there you go." Naw its all good though, it was fun putting it in. Just a quick question for anyone who's done it. Did you gouys notice your heater putting out warmer air? Cuz before I did it no matter how "warm" my engine was, the heater was always blowin out cool air but now that I did the bypass its actually a lil warmer. Like the way it should be. Haha
QUOTE(amptuttle @ Jan 5 2009, 04:53 PM) 
Seriously, it was a pain in the rear-end. I think someone out here said, "oh yea just rip the old tube out and there you go." Naw its all good though, it was fun putting it in. Just a quick question for anyone who's done it. Did you gouys notice your heater putting out warmer air? Cuz before I did it no matter how "warm" my engine was, the heater was always blowin out cool air but now that I did the bypass its actually a lil warmer. Like the way it should be. Haha
ive heard ot a TB bypass but whats the point actually? i dont know what it does...can anyone explain??? i may consider doin it.
The whole point of doing the bypass is so the TB stays a little cooler than it would have if coolant was circulating thru it once the motor is fully warm. It adds 0 hp but it does keep you from losing around 6 hp when the engine is at operating temperature since the incoming air stays cooler. Coolant is routed thru the TB to keep it from iceing up in real cold weather and in most places is not necessary. Basically,you take the hose off of the drivers side and route it to the exit hose on the other side of the TB. A section of pipe and some hose clamps joins the two hoses together.
I believe(on the lt1 anyway, not sure about your engine) that the coolant is run up past the throttle body and uses the cold air being sucked in to help cool the coolant. It does nothing really but heat up your throttle body. So basically you hank off the hose going into the throttle body, and the one coming out of it and stick them together, thus bypassing the throttle body, and keeping the TB cooler...
I haven't done it. doesnt seem to be worth the time. I doubt it would be noticeable at any perspective unless you have a magnifying glass and a dyno sheet comparing before and after.
Some people like to do every little thing though.
here's a walkthrough i found
http://timney.cz28.com/tbbypass.htm
Hope this helps!
I haven't done it. doesnt seem to be worth the time. I doubt it would be noticeable at any perspective unless you have a magnifying glass and a dyno sheet comparing before and after.
Some people like to do every little thing though.
here's a walkthrough i found
http://timney.cz28.com/tbbypass.htm
Hope this helps!
Guys and wha about the EGR valve? I don't think we'll gain anything from the bypass if we don't get rid of the EGR since it's passing hot gases from the exhaust thru the TB...
Ive personally deleted the EGR, AIR and will shortly be removing the throttle body crap... I just do not understand what they were thinking adding just that much more tubing to an already cluttered up system...
The EGR is not a tricky thing to eliminate, but in the OBDI and II cars, the PCM must be modded, or it will send the signal to open the valve and then it will modify the timing and fuel mixture to account for the exhaust gas dilution.
What the EGR does is dilute the incoming mixture with exhaust gasses, but it only does this under certain circumstances--such as under wide open throttle at low rpms and a hot engine--when exhaust gas temp is the highest and pinging is likely to happen (probably 99% of the time, the EGR does not function). If you look at it that way, it actually makes hp by reducing pinging--it also stops formation of NOX. If pinging happens, the PCM immediately hauls back timing and richens the mixture to prevent harm to the engine. The only problem with this is that it takes the PCM quite a bit of time to put everything back the way it was. Make the engine ping at the start of a street race, and you can forget about winning. Funny thing about it is that the knock sensor is so quick to send the signal to the PCM that you might never hear what caused the engine to run like a dog.
However, add 1.6 roller rockers and the increased duration of the cam lift at the valve, effectively allows a "natural" exhaust gas dilution and that means the EGR is redundant--so says GM. The LT4 Corvettes were not supposed to have an EGR system, but I have not physically seen an LT4 so that could be checked, but....THAT's what GM stated. However, add those 1.6 roller rockers and eliminate the EGR, and you still have to modify the PCM tuning to stop the engine from changing the timing and fuel mixture to account for the EGR that it expects to happen.
Also, on the AIR system, it does not affect hp at all. It is an electrically powered air pump that injects cold air into the exhaust manifold to help burn unburned exhaust gasses within the manifold that would otherwise puddle in the CAT during a cold engine start. It runs for something like 120 seconds from Key On/engine start and then turns itself off. Its purpose is to keep unburned, but still flamable exhaust gasses from igniting and blowing the crapola out of the CAT or causing cold start backfires.
Complicated when you start to work with the engine management stuff, isn't it?
What the EGR does is dilute the incoming mixture with exhaust gasses, but it only does this under certain circumstances--such as under wide open throttle at low rpms and a hot engine--when exhaust gas temp is the highest and pinging is likely to happen (probably 99% of the time, the EGR does not function). If you look at it that way, it actually makes hp by reducing pinging--it also stops formation of NOX. If pinging happens, the PCM immediately hauls back timing and richens the mixture to prevent harm to the engine. The only problem with this is that it takes the PCM quite a bit of time to put everything back the way it was. Make the engine ping at the start of a street race, and you can forget about winning. Funny thing about it is that the knock sensor is so quick to send the signal to the PCM that you might never hear what caused the engine to run like a dog.
However, add 1.6 roller rockers and the increased duration of the cam lift at the valve, effectively allows a "natural" exhaust gas dilution and that means the EGR is redundant--so says GM. The LT4 Corvettes were not supposed to have an EGR system, but I have not physically seen an LT4 so that could be checked, but....THAT's what GM stated. However, add those 1.6 roller rockers and eliminate the EGR, and you still have to modify the PCM tuning to stop the engine from changing the timing and fuel mixture to account for the EGR that it expects to happen.
Also, on the AIR system, it does not affect hp at all. It is an electrically powered air pump that injects cold air into the exhaust manifold to help burn unburned exhaust gasses within the manifold that would otherwise puddle in the CAT during a cold engine start. It runs for something like 120 seconds from Key On/engine start and then turns itself off. Its purpose is to keep unburned, but still flamable exhaust gasses from igniting and blowing the crapola out of the CAT or causing cold start backfires.
Complicated when you start to work with the engine management stuff, isn't it?
Off road y pipe=no point in cat burnoff ;D
They use that "crap" to clean the air! Caution, lungs at work.
your treasures for clean are my problem to not see the ground from my cars engine bay ;P
Lt1,
Here's the deal...year's ago, we would have killed to have the engine management system that today's engines have, and what you have done is defeat it. In my opinion...that' a really bad move. Those well-remembered engines of the early 70's and 60's, truth be told, ran like crap from day one to the last and from any one day to the next. If they weren't fouling spark plugs, the carbs were flooding or the idle air adjustment was always incorrect. On any one day, the engine could be down 10% on power, just due to the temp or humidity change, the next day, it might even be worse. Then a month later, after fixing everything, it ran even worse. By 3-6 months, new points, condenser, new spark plug wires, spark plugs, adjust the carburetor and install new muffler (I had one car, and nobody could figure it out-=-went thru a muffler and tailpipe everytime it went on a trip).
By tossing out the CAT, you have defeated whatever good the O2 sensors can do, which means that the engine now has no feedback and as such, it will never go into closed loop operation. That means, it will never fine tune itself and it will never run to max efficiency. Know why? Becuz, the PCM goes into open loop mode at approximately 80% throttle, and it will only run the last known good fuel curve that was set during closed loop operation. And since the PCM won't reach closed loop operation, it will continue to run on the basic--tuning. That is not the way to good HP.
Removing the stuff you did will cost HP (10-15%!). Considering that, was it worth to be able to see the garage floor from the engine bay? And also, I think everyone will appreciate the fact that no one wants to be following behind your car smelling your gas vapors, and that is sure to happen.
Smith County, Texas is one of those Texas counties that require an annual SMOG test, and if they conduct a sniffer test, which is required by regulation of all CAT/OBDII cars, yours will fail. Also, usually all of the equipment is looked at to see if it is there. If the car fails, it will all have to be re-installed at your expense.
Good luck.
Here's the deal...year's ago, we would have killed to have the engine management system that today's engines have, and what you have done is defeat it. In my opinion...that' a really bad move. Those well-remembered engines of the early 70's and 60's, truth be told, ran like crap from day one to the last and from any one day to the next. If they weren't fouling spark plugs, the carbs were flooding or the idle air adjustment was always incorrect. On any one day, the engine could be down 10% on power, just due to the temp or humidity change, the next day, it might even be worse. Then a month later, after fixing everything, it ran even worse. By 3-6 months, new points, condenser, new spark plug wires, spark plugs, adjust the carburetor and install new muffler (I had one car, and nobody could figure it out-=-went thru a muffler and tailpipe everytime it went on a trip).
By tossing out the CAT, you have defeated whatever good the O2 sensors can do, which means that the engine now has no feedback and as such, it will never go into closed loop operation. That means, it will never fine tune itself and it will never run to max efficiency. Know why? Becuz, the PCM goes into open loop mode at approximately 80% throttle, and it will only run the last known good fuel curve that was set during closed loop operation. And since the PCM won't reach closed loop operation, it will continue to run on the basic--tuning. That is not the way to good HP.
Removing the stuff you did will cost HP (10-15%!). Considering that, was it worth to be able to see the garage floor from the engine bay? And also, I think everyone will appreciate the fact that no one wants to be following behind your car smelling your gas vapors, and that is sure to happen.
Smith County, Texas is one of those Texas counties that require an annual SMOG test, and if they conduct a sniffer test, which is required by regulation of all CAT/OBDII cars, yours will fail. Also, usually all of the equipment is looked at to see if it is there. If the car fails, it will all have to be re-installed at your expense.
Good luck.
Im glad you think you know how my county works on smog testing.. ive had a catless car for years.. ive taken the cats off the gt.. removed all the EGR and other equipment on every car i own. It kills horse power.. I dont have a clue where you get that it cost me hp to OPEN UP THE ###### EXHAUST.. last I checked the less backpressure, the better the car runs. Why else would you put cut outs on your exhaust.. It removes back pressure, and allows the car to breathe easier. I have it dyno PROVEN to help, so I would LOVE to see where you get this information about it killing horse power. It has been tuned out of the PCM (if done correctly) doesnt make the computer do anything. The front o2's do nothing more then a wideband o2 sensor does. It rates your car at a .001 to .999 gas/air level and compensates for its burning there. The rear o2's do nothing more then make sure the cats are doing their job. (i dont even have rear 02's installed. Please list your resources to backup your theories or else i call the ultimate BS card.
Let me just make this a little easier for you...
What is a catalytic converter and what does it do?
Modern catalytic converters have a honey comb shaped core (called a monolith) that the hot gasses pass through. As the gasses pass through the honeycomb core, the hydrocarbon, carbon monoxide, and nitrogen oxide are combined with the noble metals platinum, palladium, and rhodium. This process changes the chemical structure of the polluting gasses into a non-polluting form and therefore reduces these pollutants.
Does removing the catalytic converter increase horsepower substantially?
I found that a catalytic converter reduces horsepower on a stock LT1 350 by only 4 to 5 horsepower. This is according to extensive dyno testing done by John Lingenfelter. Well, what about high performance engines, isn’t this what they complain about? Doesn’t it just kill the horsepower on a high performance engine? Again, according to the same source, a 500 horsepower engine will lose about 12 to 14 horsepower from a catalytic converter. In addition, dyno testing performed by David Vizard, the author of “How To Build Horsepower”, also backs up this research.
Does the catalytic converter decrease pollution?
Again, you may be surprised by what I have uncovered when researching this topic. The answer is yes and no. You are probably wondering how that can be. The answer is that it reduces one kind of pollution while at the same time it is contributing to another type of pollution.
According to the research(1), the catalytic converter does a very good job at eliminating the pollutants it was designed to eliminate. But, there is an untold side effect of the catalytic converter. According to the research (2,3,4,5), those same Noble metals (platinum, palladium, and rhodium) that are used to convert the HC, Co, and NOx are now showing up in our environment and the effects on health are not yet known. Once again we see that there are two sides to every coin.
Now.. if you wish to continue with this mindless dribble.. please let me know..
What is a catalytic converter and what does it do?
Modern catalytic converters have a honey comb shaped core (called a monolith) that the hot gasses pass through. As the gasses pass through the honeycomb core, the hydrocarbon, carbon monoxide, and nitrogen oxide are combined with the noble metals platinum, palladium, and rhodium. This process changes the chemical structure of the polluting gasses into a non-polluting form and therefore reduces these pollutants.
Does removing the catalytic converter increase horsepower substantially?
I found that a catalytic converter reduces horsepower on a stock LT1 350 by only 4 to 5 horsepower. This is according to extensive dyno testing done by John Lingenfelter. Well, what about high performance engines, isn’t this what they complain about? Doesn’t it just kill the horsepower on a high performance engine? Again, according to the same source, a 500 horsepower engine will lose about 12 to 14 horsepower from a catalytic converter. In addition, dyno testing performed by David Vizard, the author of “How To Build Horsepower”, also backs up this research.
Does the catalytic converter decrease pollution?
Again, you may be surprised by what I have uncovered when researching this topic. The answer is yes and no. You are probably wondering how that can be. The answer is that it reduces one kind of pollution while at the same time it is contributing to another type of pollution.
According to the research(1), the catalytic converter does a very good job at eliminating the pollutants it was designed to eliminate. But, there is an untold side effect of the catalytic converter. According to the research (2,3,4,5), those same Noble metals (platinum, palladium, and rhodium) that are used to convert the HC, Co, and NOx are now showing up in our environment and the effects on health are not yet known. Once again we see that there are two sides to every coin.
Now.. if you wish to continue with this mindless dribble.. please let me know..
It's really easy, I looked up the Smith County, Texas, regs on the Internet. Your regs say they must do a sniffer check, and if they aren't...they are illegal and unfortunately...so is your car. Remember, all they have to do is start enforcing the regs and your car is a dead duck! I'm also interested in discouraging others from making the same mistake as you did.
You might be interested to know that the entire SMOG system on the car costs 3 hp, that is all from the CATs--the other parts that you removed actually make HP, by increasing the efficiency of the engine! I quote from a well-researched and written article by Bob Fourney that you seem to have plagiarized without giving credit to Bob (owner of the other Firebird website) some years ago (I checked all the facts and they are mostly correct according to Lingenfelter, except it is 3 hp and not 4 hp, and I can furnish the quoted material that he used to write this article), and it is the same article you seemed to have used, and some of the info for this article came from me!:
"... catalytic converter reduces horsepower on a stock LT1 by only 4 (actually 3) to 5 horsepower. This is according to extensive dyno testing done by John Lingenfelter. Well, what about high performance engines, isn’t this what they complain about?? Again, according to the same source, a 500 horsepower engine will lose about 12 to 14 horsepower with a catalytic converter. So is it worth taking off a Cat for a few horsepower? I think not." You seemed to have forgotten about the "I think not" part.
This is very true. Why the big jump at 500 hp? Becuz, the CATs are only good for 150% flow increase, and the max hp they can work with is around 450--that's MAX. After that, the CATS become a restriction and the hp or pumping losses go up dramatically. I don't think your engine is getting anywhere near 500 HP, much less 450, but if it did, that is a reason to pull the CATs, esp for competition use. The big restriction in the exhaust system isn't even the cast iron headers--it's the CAT back muffler system. About 15 HP can be gained by simply replacing it and that is more than can be made by dumping the entire system and insalling "long tubes". Extrude honing the cast iron exhaust manifolds is worth another 10 HP, and that is from GM. So, by installing new and trashing your entire OEM exhaust sytem, not to mention rendering the PCM mostly inoperative, your mods have cost the engine somewhere around 30 HP!
You are new here. You don't know this, when it comes to the engine management system...I AM THE EXPERT and i wrote or contributed to a lot of those so-called articles published on that website. Don't believe me?, check the archives of this forum and you will see that the info on this forum was written by me before that website even came into being, and I know this since I was one of the two original owners of that site. I'm concerned for your car, becuz you don't have the correct facts, and I'm trying to save you some money. But, you are right...you don't have to listen to any of it, so I apologise if you feel I'm enfringing on your ability to change your car the way you want it...illegal or not.
Again, good luck.
You might be interested to know that the entire SMOG system on the car costs 3 hp, that is all from the CATs--the other parts that you removed actually make HP, by increasing the efficiency of the engine! I quote from a well-researched and written article by Bob Fourney that you seem to have plagiarized without giving credit to Bob (owner of the other Firebird website) some years ago (I checked all the facts and they are mostly correct according to Lingenfelter, except it is 3 hp and not 4 hp, and I can furnish the quoted material that he used to write this article), and it is the same article you seemed to have used, and some of the info for this article came from me!:
"... catalytic converter reduces horsepower on a stock LT1 by only 4 (actually 3) to 5 horsepower. This is according to extensive dyno testing done by John Lingenfelter. Well, what about high performance engines, isn’t this what they complain about?? Again, according to the same source, a 500 horsepower engine will lose about 12 to 14 horsepower with a catalytic converter. So is it worth taking off a Cat for a few horsepower? I think not." You seemed to have forgotten about the "I think not" part.
This is very true. Why the big jump at 500 hp? Becuz, the CATs are only good for 150% flow increase, and the max hp they can work with is around 450--that's MAX. After that, the CATS become a restriction and the hp or pumping losses go up dramatically. I don't think your engine is getting anywhere near 500 HP, much less 450, but if it did, that is a reason to pull the CATs, esp for competition use. The big restriction in the exhaust system isn't even the cast iron headers--it's the CAT back muffler system. About 15 HP can be gained by simply replacing it and that is more than can be made by dumping the entire system and insalling "long tubes". Extrude honing the cast iron exhaust manifolds is worth another 10 HP, and that is from GM. So, by installing new and trashing your entire OEM exhaust sytem, not to mention rendering the PCM mostly inoperative, your mods have cost the engine somewhere around 30 HP!
You are new here. You don't know this, when it comes to the engine management system...I AM THE EXPERT and i wrote or contributed to a lot of those so-called articles published on that website. Don't believe me?, check the archives of this forum and you will see that the info on this forum was written by me before that website even came into being, and I know this since I was one of the two original owners of that site. I'm concerned for your car, becuz you don't have the correct facts, and I'm trying to save you some money. But, you are right...you don't have to listen to any of it, so I apologise if you feel I'm enfringing on your ability to change your car the way you want it...illegal or not.
Again, good luck.
I was new here. I will be deleting my account.. I have over 3000 post on 2 other ltx lsx forums and have contributed many times over in other locations... I even posted up my thoughts about this topic on it and everyone else wants to know where it was from just to hound your ###### about it. Just because I only have 30 here does not make me a noob in any means about this.
btw.. I just went and got the car inspected.. oh my.. i passed.
btw.. I just went and got the car inspected.. oh my.. i passed.
Once again....good luck to you and your endeavers, and my apologies if you feel insulted by my information.
Anyone that signs up here just to start trouble with any of our members WILL BE DELETED. I'm closing this topic since it is no longer on the original subject.
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