Stock exhaust manifold pictures and comments

[VH 1UZ-FE]

here is a question for the exhaust manifold gurus....
I have bugger all room to put extractors, but what i wanna know is, is there that much difference in gained power from extractors to a nice flowing set of manifolds? I have seen some photos of some extractors on the net and they are huge! I am gonna try and design some exhaust manifolds to do the best possible job in the smallest amout of room. Any tips? Any info anywhere on the web or a good book i should read?
Help??? please

 

[Pro]

dude i have bugger all room too, but i'm making headers that are a very tight curve straight off the exhaust pipe. they are no thicker dimension wise than one pipe, because one port goes over, one goes straight, one goes under and the rear one is headed straight back. they then merge into a 4into1 collector and then thru the inner guard, under the footwell in the wheel well and meet under the gearbox where there is a catalytic convertor immediately after the 2into1 junction.

this way makes the whole setup four pipes tall but only one pipe wide - i have more room vertically than horizontally.

 

[madmont]

VH 1UZ-FE
TRY LOOKING AT THESE SITES FOR INFO
http://www.geocities.com/MotorCity/Track/6992/vizard.html
download pipemax1.zip from yahoo groups you will have to join[free]
http://autos.groups.yahoo.com/group/mc-engine/files/
http://www.headersbyed.com/
http://www.mgparts.co.nz/extractor_systems.html

 

[JBrady]

here is a question for the exhaust manifold gurus....
I have bugger all room to put extractors, but what i wanna know is, is there that much difference in gained power from extractors to a nice flowing set of manifolds? I have seen some photos of some extractors on the net and they are huge! I am gonna try and design some exhaust manifolds to do the best possible job in the smallest amout of room. Any tips? Any info anywhere on the web or a good book i should read?
Help??? please

Here is an excellent site with some technical articles and of course the nicest parts available: http://www.burnsstainless.com/

The MOST important part of any manifold is the transition areas, the areas where one or more tubes merge together. Long tube, equal length designs with quality merge collectors using proper tube diameters will make the most power over the widest RPM range. However, a good flowing design can give you respectable power.

 

[Lexurious]

You have to remember this engine can make good power with a decent exhaust, which is not what Toyota were going for. A more restrictive exhaust allows more driveability and more power in the lower rev range, which is what they were trying to achive I think.

 

[JBrady]

You have to remember this engine can make good power with a decent exhaust, which is not what Toyota were going for. A more restrictive exhaust allows more driveability and more power in the lower rev range, which is what they were trying to achive I think.

Lexurious, actually a more restrictive exhaust system makes LESS power accross the entire rev range. If you reduced the exhaust to 1/2" pipes you would have a HIGHLY restrictive system and obviously not more power... anywhere... The often repeated "backpressure" theory is WRONG... the real cause of low end power loss is a loss of velocity with the result of actually LESS flow at low rpm. Most people simply assume (understandably but still incorrectly) that bigger pipes have better flow. The truth is bigger pipes kill velocity and that allows reversion at low rpms and hence kills low rpm torque. The stock manifolds are a combination of a durable design that is quiet and reliable without hurting power. The poor flow design actually helps prevent reversion... however... if you can design a manifold properly you will GAIN power accross the range. Just slapping big pipes on though is NOT the answer. As I pointed out, transition areas are critical. Small diameter pipe can flow a LOT as long as the transitions are smooth. Consider how much power some 2JZ-GTE engines make with a single 3" pipe!