Originally Posted by boosted hybrid

No, egr is the story. If you are discharging hot exhaust gas into the compressor that is one thing, if the discharge is pointed in the complete opposite direction and power loss is severe that is another.

Exhaust gas recirculation kills power. EGR is for emissions purposes on OEM applications. N0x is greatly reduced using EGR, and thus lowers formation for emissions purposes. This also reduces power potential from an engine.

In a forced induction application, the compressor inlet generally sits within the area near the dumptube discharge. With no dumptube, the wastegate exhaust gas discharge is expelled into the area in the engine bay. Even if the discharge is not pointed in the direction of the compressor inlet (i.e wastage discharge pointed downwards on EL manifolds, wastegate discharge pointed towards radiator on log manifolds, etc), the available oxygen content in the engine bay is severly reduced. When you compromise the available oxygen being injested into the engine through the compressor inlet (the only available air source), you lose power. Less oxygen available in the combustion process, less cylinder pressure developed and less torque and power produced.

There has been many customers that come for tuning that have a dumptube, but does not go underneath the oil pan. While on the dyno, the discharge reflects off of the floor of the shop and gets injested into the engine. By simply adding a flexible extension on the dumptube to bring the exhaust gas underneath the car, i have seen gains of anywhere from 10-50whp. I have had multiple customers cars that dont have a dumptube at all, and by adding a dumptube underneath the oil pan have picked up between 20-90whp worth of power.

Here are some examples that i have collected from past tuning sessions:



*This was on an LS engine that had no dumptube. It was using a log manifold, with a tial 38mm gate. The discharge was spraying downwards in the engine bay, with the compressor inlet facing the passenger side. By simply fabricating a dumptube that went underneath the oil pan the gains seen in the dynochart were realized. Solid lines being same psi and tune with just the dumptube added.



*This was on a FR equipped built b16a engine. The FR kits do not come with dumptubes (nor do any other kits out there). The compressor outlet on the 44mm gate was pointed towards the radiator, compressor inlet on drivers side. By rotating the dumptube up towards the ceiling, and adding a 5" extension 90whp worth of power at the same psi level and tune were realized. NO OTHER CHANGES WERE MADE! EGR is very significant.



*This car had a dumptube with a traditional log manifold. It pointed downward and stopped half way down the radiator. By simply adding a 90 extension to the dumptube and pointing the discharge under the oil pan, the gains showed were realized.

I have many more graphs that prove this theory correct. By adding a dumptube that goes under the oil pan, or adding an extension to an existing one power output is dramatically increased. It not only makes more power, but the engines ability to knock is greatly reduced. Its a simple, overlooked item that will make a dramatical power difference.

Originally Posted by evoforlife

What about routing it back into the exhaust as well would this help too?

Originally Posted by Evoryder

Good info. I have been meaning to extend my tube.

Originally Posted by 4doorstreetbike

Good test but I really don't believe that your gonna gain up to 50 whp.I agree your sucking back in hot air when it's on the dyno cause the car is sitting in one spot but when you drive on the street the car is moving at high speed's so the hot air doesn't get trapped anywhere..As far as having it recirculated yes you lose power ,then you'll see 10 to 50 whp gains from dumping it..

Originally Posted by igo4bmx

but also tuning at certain boost levels on the dyno you motor will see more o2 during a street drive possibly leaning out the dyno tune

Originally Posted by 4doorstreetbike

Around 6 years ago I has a fully built buick grand national with a rec.dump I had my local tuner convince me that it would free up 50 whp cause there were seeing these gains on turbo hondas when you did this mod I only picked up 12 whp but my turbo spooled alot faster and held more boost up top better..Hondas are not a good example thus there not turbo charged from the factory so there really restricted so when you do that to them that's why they see gains when doing something like this..If the pipe is half way down your fine but all the way to the pan is safer due to any flames or excess hot gases being released!!I rememberd mine is all the way down but that's how many kit came.

Originally Posted by [I.R.A.]_FBi

you do realise exhaust has been stripped of most of the combustible oxygen right?

Originally Posted by 4doorstreetbike

Around 6 years ago I has a fully built buick grand national with a rec.dump I had my local tuner convince me that it would free up 50 whp cause there were seeing these gains on turbo hondas when you did this mod I only picked up 12 whp but my turbo spooled alot faster and held more boost up top better..Hondas are not a good example thus there not turbo charged from the factory so there really restricted so when you do that to them that's why they see gains when doing something like this..If the pipe is half way down your fine but all the way to the pan is safer due to any flames or excess hot gases being released!!I rememberd mine is all the way down but that's how many kit came.

Originally Posted by 4doorstreetbike

How far is your dump??

Originally Posted by Evoryder

Hondas make good power thanks to high compression. They don't last too long if not built.