Thread: Wastegate Dump Tube Routing (Dyno Comparison)

I know this is obvious to most people and most of the Nissan community is internal gated and wouldn't have to worry about this.. but I am sharing just for reference.

This has always been a big problem with cars that come in to get tuned, either the dump tube is non-existent or it is pointed right at the ground or vented near the turbo inlet and/or filter.

Here is a comparison of a turbo H22A that I tuned today and after the first pull I immediately knew something was not quite right and as I suspected the dump tube was directed near the turbo inlet causing exhaust contamination of the incoming intake charge.

I swapped the wastegate around and directed the dump tube into the air, away from the turbo and picked up nearly 50 whp at the same pressure without any other changes.

I have had to fix this numerous other times in the past so it wasn't a big deal, but I figured I could at least post up this comparison to those who wouldn't think twice about either not running a dump tube or routing it near the turbo inlet.

Just something to think about next time you are constructing a dump tube.

i would like to see what the difference would be with no dump tube compared to having one and changing the lengths. maybe i will give it a shot

Free money!

My dump tube is actually very long. It dumps behind the tranny. This is actually very interesting info.

Excellent.

In my experience, the dump tube should be pointed away from the engine bay area. So dumping it back behind the trans is a good idea.

Some other things that aren't so good are dumping it directly toward the ground. When you are on the dyno it will reflect right off the ground and fill the bay with exhaust gas, causing a similar situation.

Remember, this is a drastic case, most are not quite this bad.

And when on the road moving, dump to the ground is not so bad. Just sucks for dyno tuning. =/

Correct BUT it makes life very frustrating on the dyno when this happens.

I honestly can't tell you how many times I have had to extend and/or move a dump tube to alleviate this problem while a car is on the dyno.

It is just something that customers often over look.

Some of that parts store bendable exhaust hose/tube might be cheap, and make your life at the shop easier for when folks bring in cars with less than ideal setups. I guess it won't work for everything though. Might not hold up to the heat? Worth a try.

I actually do use this quite often!!

I have some flexible tubing and a bungee chord that I put on when I can, but on some applications it is near impossible to install without having it fall off during a pull.

I also actually keep a spare 38mm wastegate flange with an assortment of pipe on hand so I can route it to a better location if needed.

The idea here is for the owners to know why they should have a properly routed dump tube BEFORE heading to the dyno. Having to rig stuff like this up takes away from tuning time.