Turbo Exhaust and power wastegates and dumps
 

Wondering how short can you go before the exhaust is hindering power?

When one pulse shoots out it pulls the next pulse with a vaccume right?

I was looking at my vented 12" wastegate the other day and thinking it may be holding some power back. I only use a tick more fuel after 7500 rpm with my dump open 3-4 ft away so I know anything shorter has to be bad?


I am thinking about extending my vented wastegate to 3-4 feet as well. What do you think?

only a good 6" i would think, 12" is probably the ideal length imo

the length isn't nearly as important on a turbo motor as it is on an NA motor. After the Exhaust gasses hit the turbo the the exhaust pulses will have minimal effect.

It's not going to make a noticeable difference. As it is, venting a wastegate to atmosphere is going to give you more power than recirculating it, which is what plenty of high horsepower cars do (although a well designed recirculated wastegate dump causes only a little bit of restriction and power loss) .

Your fuel curve, in actual pulsewidth or duty cycle, follows the power and torque curve. A stock FD's fuel consumption drops off after 6000 for example. My 386rwhp car needed less fuel after about 7000rpm and that was with a big street port and a T04S 60-1 turbo on an HKS log manifold.

The diameter and length of the runners to the turbo itself is much more important. What manifold are you using? What wastegate are you using and is your boost under control in all weather conditions?

Wastegates do not flow through the turbo. It would be like having a 12'' exhaust on your NA.
It has been proven that too short of exhaust makes less power than the right tuned length.

When I open my 3" dump it only helps above 7500rpm, It may very well be slowing me down under 6000 rpm.

Looking for the correct lenght for 5500-7500 rpm?

I'm guessing 6-7 feet ???

How fast does the exhaust pulse travel?

3" versus what?

I'd like to see proof that your 3" WG dump tube is "slowing you down"?

You're using a merged, single WG, right?
If so, the pulses are already fucked up prior to the wastegate.
Are you talking about changing the pipes prior to the WG???
Changing the WG dump is not going to really affect anything unless we're talking about merging back into the exhaust or dumping to atmosphere...or, your WG dump tube is too small to begin with.


-Ted

Ok, lets clear this up a bit.

I have a hks log mainifold with a 50mm wastegate and a 12" tube off off it open to atmosphere. The exhaust is 3" off the turbo with a electronic dump 3-4 feet down.

Now I have done hundreds(no lie, I data log like a mofo) of runs with main exhaust dump open and closed. It only runs a tick leaner after 7500 rpm and is the same if not richer down low. I really only use it to scare small children and Harleys... lOl


I'm just going to add a few feet on to the wastegate "dump" tube and see if there is a positive effect. Leaner =more power.

Just wanted to bouce my ideas around if someone else had done this.