crazy high egts HELP

I already mentioned this in your dyno thread, but it needs to be repeated.

When you enlarged the stock HX35 wastegate to 30mm+, the little actuator no longer has a strong enough spring to hold it closed. Drive pressure combined with boost working internally on the actuator lets the gate crack open at 10-15 psi. When that large wastegate cracks open, it diverts too much drive pressure from the HX35 and airflow suffers.

Obviously, low airflow hurt your dyno numbers, and it apparently hurt your towing performance as EGT's soared on your last heavy towing adventure.

If you're a machinist, build an adjustable spring controller for the HX35 wastegate using a heavy spring and a threaded rod for easy adjustment.

Your best temporary fix would be to pinch the wastegate line shut with a pair of vice grips so that boost does not help open the wastegate. It will still open early because the wastegate is too large and drive pressure will easily overcome the spring tension in the wastegate actuator, but, it will be better than it is right now.

Cutting back top-end fueling with a fuel plate will also help with EGT's. This will also severely limit horsepower. If you fix the wastegate problem, you'll gain horsepower and have better EGT control.
 
I was running a HX35 and S471 T4 at first towing the egts were 850 to 900 empty trailer. I then put the biggest HX40 turbine 67mm outlet and 60mm compressor oh the waste gate is spring operated now. Drive pressure and boost are 1 to1 or better 650 to 700 egts towing empty. Now can pull the mountains at almost wot and stay under 1200 deg loaded. timing is 26* too would like to try 20* some time.
 
Big Blue24 said:
When you enlarged the stock HX35 wastegate to 30mm+, the little actuator no longer has a strong enough spring to hold it closed. Drive pressure combined with boost working internally on the actuator lets the gate crack open at 10-15 psi. When that large wastegate cracks open, it diverts too much drive pressure from the HX35 and airflow suffers.
Click to expand...


^That and lower rpms towing.

On a side note BigBlue have you found what the limit is to enlarging the wastegate without have it open so much earlier? Like a happy medium?

Such as halfway between stock size and 30mm+?
 
On the HX35, the stock wastegate flapper puck is only like 1.125" or 29mm wide. I like to open up the wastegate no more than 22.2mm or 7/8" for sealing purposes. The puck is not perfectly fixed in place so it needs a good amount of overlap to ensure a good seal. A partially sealed wastegate port leads to slow spoolup, and could burn a hole through the edge of the puck/wastegate port.

On the He351, the stock wastegate flapper puck is closer to 1.25" or 32mm. I opened it up to 26mm and cracking pressure dropped from 26 psi boost to 19 psi. With the wastegate line completely detached, drive pressure would blow the gate open around 36-38 psi boost. Stock He351, unmodified gate size with the boost reference line pinched-off, boost will climb to 50+ psi before drive pressure opens the gate.
 
stangman95 said:
yeah it was below 2000rpm. 5th gear at 55mph was 1750rpm or so. although when i went to 4th it would cool down slightly but still pretty high. maybe 1150* or so.
Click to expand...

Pulling that heavy in 5th will work the nut loose in the trans. Try fourth and Egts will go way down.
 
I had the same set up at one point in my 98 with a hx35 wg14cm over a HT60 with Full Cuts, 370s, #100 plate, 19deg timing, stock lift pump and heavy 215 pump AFC Spring. Its made 540hp and EGT towing around 8k would be around 1150-1200 up a grade, but as others have said the key is keeping RPM up. I would have been going 70-75mph at 2000 or above rpm. Just a good comparison for you.
 
Go ahead and make a spring style wastegate with a nice stiff spring, put in a stiffer afc spring, back off the pre boost screw a bit, and carve a 100 plate, might have to slide the afc back toward the rear of the pump if you can't back off the pre boost screw enough. You get this done then you have more reasonable parameters to keep your fuel delivery in. Twins can really mess with your afc and make it hard to tune.
 
i would put the plate back in it and scoot it back to about stockish.. and tighten up on the afc spring so you can get your turbo to spool before you start feeding it more fuel.
 
I can hit 1,100-1,200 empty in either one of my trucks if I lug the engine enough. RPM's, man.
 
JQmile said:
I can hit 1,100-1,200 empty in either one of my trucks if I lug the engine enough. RPM's, man.
Click to expand...

that really is nothing though. enough heat/fuel to make a flame out the stack means high EGTs usually. hahaha. i have a video on my old phone.

Garrett
 
SSpeeDEMONSS said:
that really is nothing though. enough heat/fuel to make a flame out the stack means high EGTs usually. hahaha. i have a video on my old phone.
Garrett
Click to expand...

I don't look at EGT on the dyno, I just try to hit all my buttons at the right time. Now that I am running down the strip I will have to start worrying though.
 
9 seconds at 1800* has to be less harmful than 15 seconds at 1600*.....


Jason, just run a 9, then you don't need to worry about EGT.
 
You must log in or register to reply here.
Back
Top