Exhaust manifold upgrade

The stock exhaust manifold is bad. After all this years it has cracks, and the pipes inside are not large enough.







There are no aftermarket exhaust manifold on the market, but there are some original exhaust that can be made to fit the ACE engine.

I took the manifold of an 2.0 20v 5 cylinder engine, and modified it to fit the ACE head.





The basic idea is to cut one pipe off, and make it fit the 4 cylinder head. The exhaust is made of inoxxx, so it is worth a try.



one pipe off.





now 2 flanges are turned in the wrong way around, because the engineers at audi when making the 5 cylinder engine have put one cylinder at the gearbox side of the engine, not in front of the engine as they should have. so now it is time to cut 2 flanges and turn them as they should be.



this is the ACE head with the 2 cut flanges on



the first pipe is now spot on, ready to be spot welded

but! the third is not on target because of the different distanced between the intake ducts.

so the third pipe must be cut off



and from the pipe for the fifth cylinder i have cut off first, craft the missing part



now everything is perfect



this is how it looks on the head

but new problems arise:

the throttle body now touches the exhaust manifold.



there is the 2.0 16v 6A throttle, but i think it will not work with the ace engine.

so i took the 2.3 10v (NG) throttle, and it fits ok



I took the manifold to a professional welder, and he did a good job. I also cleaned it.

because the manifold is close to the throttle body, i decided to wrap it with graphite heat wrap. Maybe i will gain a horsepower too



this is a time consuming job, but with some practice it gets perfect (not like this )





2 pipes



with every pipe you wrap it gets harder...







but it looks nice

the test in the engine bay brought new issues.

there is no room for the U shaped intake pipe, so it needs to be removed



i modified the intake to collect the air directly into the airbox

the other issue is that the downpipe does not connect to the manifold



i will have to customize the down pipe. I will report when i finish.

Hello,
Great job!
Can you update dead picture links. Please

hey.

links repaired. i still didnt fit the exhaust, but the downpipe is customized and everything is ready for installation.

this is the modified downpipe



this is the problem i have now...

i have to get rid of this gap...

the flanges corrected



the downpipe is perfect now



so next thing was to remove the stock catalytic converter with a sport one and finish the 2,5" pipe.

i choosen a 200 cell metallic cat (150€ one ebay.de) just to be sure to pass the exhaust gasses tests



next i removed the stock flange off the stock cat, and rebored it to fit the 2,5" pipe





next thing was to fit the cat and to make a pipe...





and this is the finished exhaust



stock 20v exhaust manifold shield to finish the job



this tubular manifold mod is awesome, it is a lot of work, but the result is fantastic, much power and even more torque gained with it.