# intake and exhaust manifold info by NLS



## nothing-leaves-stock (Mar 1, 2005)

got sick of people guessing at stuff...so i cut apart a intake and exhaust manifold for a 2007 2.5L. measured them and now posting it up so there are pictures and facts out for everyone. 

cut and measured as best as i could in house, spec are not too .0000000000001 specs. i mic'd and measured stuff. 

hope this info is helpful to understand more of the crazy 2.5L 

--josh 

1st... cut open exhaust manifold HAS runners. but they are NOT sealed. the 02 bung is wide open and the "collector" is not welded and you can see a LOT of air space between the runners. so the exhaust fills the full outer cover area, its not just a heat sheild. it has exhaust flowing in it as was...very wierd imo. 










inside the lower flange looking up torwards engine flange 










02 sensor is open to the outer case AND the collector of all 5 cylinders. 










exhaust manifold specs. 
-outlet to downpipe is 2.25'' ID 
-runners are 1.39'' ID 
-exhaust port- 1.43'' 
-2.5'' from head flange to center of valve stem 
wierd part...no real equals :sly: 
runner from head flange to center of outlet to downpipe. 
#1 cyl- 14.25'' 
#2 cyl- 12.25'' 
#3 cyl- 11.5'' 
#4 cyl- 12.25" 
#5 cyl- 13.25'' 

intake bits. 


























-pletum size ave is 11''x6.25''(inside measurments). BUT not a full open box because of runners built in and well as differnt shapes inside(not a smooth box). so volume is smaller. 

-throttle body ID opening 2.75'' 
-runner opening ID at head flange- 1.10''x1.95'' 
-runner ID in center of runner 1''x1.87'' 
-runner opening instead intake 1.80''x1.95 
-runner length from flange to opening in intake- 16.25'' 
-head flange to intake center of valve stem- 2.75'' 
-head intake port-.94''x1.33'' 

i'll add more if i get more..... 
-josh


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## dhenry (Feb 10, 2009)

cool stuff:thumbup:


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## DerekH (Sep 4, 2010)

Thanks Josh! 

Great info. That stock exhaust mani is pretty dumb lol.


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## thygreyt (Jun 7, 2009)

awesome! i had never seen the exhaust mani like that. 

thanks for sharing.


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## driftme (Apr 12, 2008)

pretty cool! thanks =]


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## eatrach (May 13, 2004)

so josh, an aftermarket exhaust manifold will be beneficial for this car?


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## vwluger22 (Jan 25, 2005)

:thumbup:

Sent from my phone.


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## H3LVTCA (Oct 27, 2004)

Very cool! :thumbup:


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## sagerabbit (Aug 14, 2007)

Well done, Josh.


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## nothing-leaves-stock (Mar 1, 2005)

eatrach said:


> so josh, an aftermarket exhaust manifold will be beneficial for this car?


 yes, but not a long tube crazy one. short tube, equal lenght...yes. i find it funny the that oem one is 2'' differnce between runner. no idea why! and i'd LOVE to know why the case holds exhaust as well.


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## GTACanuck (Feb 20, 2009)

The fact that the collector and runners are not welded blows my mind...


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## DerekH (Sep 4, 2010)

I would imagine it is another way vw engineered this engine to be worse just like the intake mani. Or possibly additional back pressure?


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## eatrach (May 13, 2004)

nothing-leaves-stock said:


> yes, but not a long tube crazy one. short tube, equal length...


 josh, who makes a good exhaust manifold? 
I am *assuming* that VW engineers wanted to combat unwanted heat in the bay area; thus, an additional steel sleeve for the manifold will keep heat at a minimal. That is a wrong way to fight it.


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## nothing-leaves-stock (Mar 1, 2005)

it wouldn't make more back pressure. 

i love the EVO header. hands down the best design, construction and best for performace


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## tdogg74 (Mar 1, 2002)

nothing-leaves-stock said:


> yes, but not a long tube crazy one. short tube, equal lenght...yes. i find it funny the that oem one is 2'' differnce between runner. no idea why! and i'd LOVE to know why the case holds exhaust as well.


 Possibly to equalize pulse pressure evenly due to the uneven length runners? Sort of like what an X/H pipe does for a dual exhaust set-up?


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## eatrach (May 13, 2004)

911_fan said:


> Possibly to equalize pulse pressure evenly due to the uneven length runners? Sort of like what an X/H pipe does for a dual exhaust set-up?


 hmm interesting point


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## nothing-leaves-stock (Mar 1, 2005)

why? ports are qual length. only motor the would make sence on is a vr6 because differnt lenght head port


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## tdogg74 (Mar 1, 2002)

Theoretically, if the runners are of unequal length to the collector, the pulse frequency back to the exhaust valve will be at different time intervals. These uneven pulses would create a some-what 'unclean' power band....a very untuned exhaust. Having the runners open to each other, yet sealed/encased in the outer manifold shell, solves this problem and equalizes the pressure. Much like the plenum of an intake manifold. 

Is there a space issue behind the block to the firewall on these cars? This compact design would make sense if that was the case. Would also have been a cost effective solution for VW engineers. 

*edit* Also think about Subaru boxer exhaust manifolds. They get their distinct sound from the use of unequal length runners. Equalize them, and the car sounds like every other 4-banga on the market.


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## nothing-leaves-stock (Mar 1, 2005)

now thats a possible idea! interesting 

no space issue. infact theres a ton of room behind the motor. one of the easiest manifold to take off.


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## eatrach (May 13, 2004)

Josh, who sells Evo Headers? tried to do a search, but the only I came up with is headers for Mitsubishi lancer 

Edit: never mind, I found the company's website.


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## thygreyt (Jun 7, 2009)

mjmautohaus.com


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## dhenry (Feb 10, 2009)

eatrach said:


> Josh, who sells Evo Headers? tried to do a search, but the only I came up with is headers for Mitsubishi lancer
> 
> Edit: never mind, I found the company's website.


 maybe some other people might be interested in buying them, like mentioned above mjmautohuas has them, and also NGP sells them too. but it takes like a month to get it made.


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## nothing-leaves-stock (Mar 1, 2005)

go with NGP. they are a SUPER great company to deal with.


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## eatrach (May 13, 2004)

i wish there is group buy


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## cracKness (Feb 20, 2007)

Something about that $1200 price tag makes it less appealing...


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## dhenry (Feb 10, 2009)

cracKness said:


> Something about that $1200 price tag makes it less appealing...


 yeah same here, also if your gonna turbo later down the road that would be a waste. use that $$ towards turbo unless staying N/A


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## MK5CNY (Sep 4, 2007)

I'll have to research some old EC mags, but I'm wondering if this has a role in harmonic reduction within a 5cyl. The EC article was an interview with the VW pres an EC on the new 5cyl versus the Audi's past engine.


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## MLue1 (Apr 27, 2008)

*Thanks*

Sorry to revive an old thread, except to say thanks to NLS, his cut away is helping me greatly with a project I'm working on.

The inline 5 cylinder has always been a bit of a riddle in comparison to tuning 6 or 8 cylinder engines, even Volvo has trouble getting the most from it.


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