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Restrictive Exhaust Manifold?

 
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  #11 (permalink)  
Old 15 Aug 2012, 03:03 am
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Default Re: Restrictive Exhaust Manifold?

Quote:
Originally Posted by NicksCruiser View Post
Thanks for the link, looks cool. Might consider it although I can prob just cut the stock elbow off the manifold and weld on a bigger one would that work or no? It's a cheaper way to go but if it saves money I'm all for it.
you should know the type of metal you're planning on welding. iirc, the exhuast manifold has a high nickel content in the cast so you can't just slap on a piece of SS and hope it works. I think i'd go with someone who has experience in this process.
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  #12 (permalink)  
Old 15 Aug 2012, 11:08 am
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Default Re: Restrictive Exhaust Manifold?

Things seldom mentioned when someone asks about improving the power output.

How often do you run high RPM and WOT ?
(High RPM would be above 5600rpm
WOT=Wide Open Throttle)


Or another way to put it, How often do you do full throttle acceleration trails.

If the answer is seldom and you need to be honest with yourself then going to 3" exhaust and manifold porting will yield very little gains per dollar and labor spent. In fact you will actually lose some badly needed low end torque. Your MPG may also be effected in the negative? The exhaust needs to flow well but it also needs to maintain a high temperature to keep exhaust velocity high. Otherwise it is wasted energy.So if you are going to 1/4 mile your PT, use it on the track or expect some serious Street Challenges think about what you are planning to mod and make an intelligent derision.

A good CAT back 2 1/2 system that does not split your eardrums and muddles the "cool" tunes as you drive is far better way to cruise!

A well maintained 41TE should well handle a 40whp increase if Stage 1 upgrade is added.
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Last edited by NitroPT; 15 Aug 2012 at 11:11 am.
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  #13 (permalink)  
Old 15 Aug 2012, 11:35 am
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Default Re: Restrictive Exhaust Manifold?

Quote:
Originally Posted by NitroPT View Post
Things seldom mentioned when someone asks about improving the power output.

How often do you run high RPM and WOT ?
(High RPM would be above 5600rpm
WOT=Wide Open Throttle)


Or another way to put it, How often do you do full throttle acceleration trails.

If the answer is seldom and you need to be honest with yourself then going to 3" exhaust and manifold porting will yield very little gains per dollar and labor spent. In fact you will actually lose some badly needed low end torque. Your MPG may also be effected in the negative? The exhaust needs to flow well but it also needs to maintain a high temperature to keep exhaust velocity high. Otherwise it is wasted energy.So if you are going to 1/4 mile your PT, use it on the track or expect some serious Street Challenges think about what you are planning to mod and make an intelligent derision.

A good CAT back 2 1/2 system that does not split your eardrums and muddles the "cool" tunes as you drive is far better way to cruise!

A well maintained 41TE should well handle a 40whp increase if Stage 1 upgrade is added.


He didnt even ask about gas mileage, are you trying to sell him something? He owns a PT, not a mini.
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  #14 (permalink)  
Old 15 Aug 2012, 12:40 pm
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Default Re: Restrictive Exhaust Manifold?

I have no idea bout turbo thingys, but I'm positive this is the turbo mani you need:



Fit's your head!!!
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  #15 (permalink)  
Old 15 Aug 2012, 12:41 pm
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Default Re: Restrictive Exhaust Manifold?

This is a PT forum, let's keep it that way!
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Old 15 Aug 2012, 02:27 pm
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Default Re: Restrictive Exhaust Manifold?

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Originally Posted by Busa_Powered View Post
He didnt even ask about gas mileage, are you trying to sell him something? He owns a PT, not a mini.
It doesn't hurt to mention the consequences even if they weren't directly asked for. Welding in a bigger "elbow" in the manifold might look like a way to uncork some free power but it probably would only benefit in the high RPM range and may slow exhaust flow at low RPM because of the bigger cross section hurting response, drivability and maybe even mileage. What's wrong with discussing and thinking about any of that?
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Old 15 Aug 2012, 03:38 pm
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Default Re: Restrictive Exhaust Manifold?

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Originally Posted by Busa_Powered View Post
He didnt even ask about gas mileage, are you trying to sell him something? He owns a PT, not a mini.
Auh...not sure where that came from? What does a MINI have to do with anything in this thread or my post? You may want to re-read my post agian!

Besides please tell me what you think I could possibly be selling? he has a PT not a MINI!

my response quote:
"Your MPG may also be effected in the negative?"

This statement is something almost no one thinks abut when going to larger diameter exhaust system on a STREET driven vehicle. So I thought not only valuable information but appropriate in this thread and my response which is and not MINI specific? Where ever did you get MINI in any of this? That whole quote was 9 words in my whole response and that's what you read into my 200 word response?

Besides the MIN is not even close to the only car,boat,motorcycle or even airplane I have modded, but I can't add them all on this forum. I just thought the MINI was the in the same unique class as the PT. Not like some of you that own a PT and a Corvette? lol Ya now they are close! NOT! Maybe I should do a thread on my AC Cobra? lol






One of my 2 AC Cobra's I owned and built was the famous Arntz cobra #001 AC Cobra. This would be Steve Artntz personal very first unfinished "kit" Cobra. So more then just a MINI for me.
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Last edited by NitroPT; 15 Aug 2012 at 05:11 pm.
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  #18 (permalink)  
Old 15 Aug 2012, 04:15 pm
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Default Re: Restrictive Exhaust Manifold?

Quote:
Originally Posted by Kawizx9r View Post
This is a PT forum, let's keep it that way!
That WILL fit the PT.
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  #19 (permalink)  
Old 15 Aug 2012, 05:00 pm
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Default Re: Restrictive Exhaust Manifold?

Gosh here I go having to write another long tech post.


The stock PT’s exhaust systems is not capable of flowing sufficient exhaust gas at high engine speeds. Because of the CAT, the exhaust manifold, small diameter secondary exhaust pipe and restrictive pipe bends, muffler and resonators. Any added engine performance parts that will increase the power level increase proportionate amounts of exhaust which will affect the already deficient stock exhaust system. But the size of exhaust piping directly relates to exhaust flow. If you choose a diameter that is too small it will constrict flow and create excessive back-pressure. This is called a weak exhaust flow which reduces engine power and fuel efficiency (poor MPG) by forcing the engines pistons into firing harder to move the exhaust gases. On the other hand an exhaust pipe diameter to large increases flow but can reduce the EGT’s which slows velocity and you actually lose power and fuel inefficiency (poor MPG) rather then gain. In both cases you cause contamination of the incoming fresh air/fuel because the engine cannot properly rid the cylinders of exhaust gas. Also there is a residual of exhaust material remaining in the cylinders that prevents maximum filling during intake cycles even with direct port fuel injection. You can see this in a ECU OBDII DATA log as a short term lean AFR. Normally this situation only worsens as you increase the RPMs. So ultimately those big 3’ inch exhaust on a STREET car looks good sounds mean and reduces your engines power instead of increasing it! Lol.
A Street driven engine that sees less high and extended RPM use can get very little benefits by a 3’ inch exhaust. The facts are simply at low rpm, the flow rate tends to be slow regardless of exhaust pipe size. So why go to such an increase of 3'? Other things not mention also effect the exhaust flow like ignition timing and compression ration. Without considering these and a few other things you can actually create problems like pre ignition or lean conditions at certain RPM levels.
It is not as easy as going on a forum and reading what everybody else has done and think it will work or work well with your specific engine and driving requirements. It is a careful consideration of how changing any part of the exhaust system is ultimately going to affect the overall engine reliability and efficiency.




Anyone debating my response will need to be prepared to discuss with me Thermal Dynamic principles and how they apply to an internal combustion engine specifically having to do with the PT's 2.4 turbo engine, the math of Volumetric efficiency tables and calculation for a 2.4 Turbo PT.
I am am working on them now!
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Last edited by NitroPT; 15 Aug 2012 at 05:04 pm.
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  #20 (permalink)  
Old 15 Aug 2012, 05:23 pm
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Default Re: Restrictive Exhaust Manifold?

I didn't notice any decrease on MPG after I installed my 3" system..
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