Engine/Transmission (1998.5 - 2002) Do it yourself adjustable boost elbow

[jlccc]

In my quest to reduce the EGT's on my ETH, I've decided to try a homemade, in-cab-adjustable boost elbow. I'm going to buy about 15' of 1/4" hose, a 'T' fitting and a needle valve. Then I'll hook up the travel trailer and then go climb my favorite long steep hill. Hopefully, playing with the needle valve (which, in turn, should help me control when the wastegate opens) will pay some dividends.

 

[dmurdock]

i see you have the e-z and elbow... what will reducing the boost do but increase egt's???

 

[jlccc]

Originally posted by dmurdock

i see you have the e-z and elbow... what will reducing the boost do but increase egt's???

I didn't say anything about reducing boost. My aim is to see if I can bleed off some of the "excess" exhaust and keep the same amount of boost. Meaning, I think my 12cm housing is "choked" and I may be able to send some of that off through the wastegate without reducing boost.

 

[LSMITH]

There is such a thing as "too much boost" for any fueling rate, and there is NOTHING wrong with having 1300 EGT for a max.



Edit: I have done this and it works well. Take your boost down until EGT gets to about 1250-1300 on a long HARD pull. When you get more fuel you will find that max power and lowest EGT are at about 34-36 PSI with the stock HX-35 12cm even if you have the fuel to make over 40 PSI. If you have just the EZ you will find NO gain in performance over about 26 PSI, and EGT will be low enough to pull as hard as you care to.

 

[jlccc]

Originally posted by LSMITH

There is such a thing as "too much boost" for any fueling rate

[snip]

If you have just the EZ you will find NO gain in performance over about 26 PSI, and EGT will be low enough to pull as hard as you care to.

Yes, this is what my research has led me to understand. This is exactly the same thing that the "turbo-master" wastegate actuator is supposed to do. I want to vent through the wastegate any extra exhaust beyond whatever is required for coolest EGT's. When the turbo housing gets too restrictive it doesn't matter how much boost you make, you can't get it through the exhaust system (which includes the turbine housing itself if you are holding the wastegate closed for too long).



So, yes, Lsmith, I agree with you and hope to prove it to myself shortly.