LB7: s475 over stock high egts

[danzick]

Hey everyone. I'm sure a lot of you read my questions in my build thread but I figured I'd start a thread for my problems. Truck spikes 40 on the max effort tune, but seems to fade to 36 38 by 85-90. Egts are around 1500 and up. Pulls hard and fun to drive, but the egts are not fun. I talked to Scott at sdp and he said only running 40 psi should still not be causing that high of temps. Although he was definitely not overly helpful, but I understand as it wasn't his kit.

 

[Dirtymaxx03]

Id check for boost/drive pressure leaks. You should be seeing more boost then that on a max effort tune

 

[mike diesel]

1500 isnt bad.

 

[danzick]

I pressurized from the inlet of the 75 to the y bridge. I cannot do much over 22 or it just blows the caps off. I can hear my oil gurgling a little. I also have a tiny leak at the stock turbo horn. You can barely hear it with soapy water sprayed on it. It takes Atleast 30 seconds to bleed from 22 to about 4 or 5. If not a minute. Would a leak that small cause a big issue? There is no black marks anywhere on the hot side.

 

[mike diesel]

Those leaks are too small to worry about.

 

[danzick]

I thought so, but I don't like to assume anything.

 

[delong_1]

How much boost is the 75 putting out?

 

[wrcknkrw]

You should be considerably higher on boost and lower egts. I have two leaks currently but can easily reach 46-48 psi on a 2600 pulse tune. Before my leaks the same tune would pull 54-55 psi. With my leaks that I have currently I still see 1350 and below, that's not max effort but the same 2600 pulse tune.

 

[danzick]

Is that with a regulator for the stock waste gate? I have not had any luck with the regulator I'm running. Going to order a different one. Just wouldnt think my egts would be this high even at 40.

 

[danzick]

How much boost is the 75 putting out?

I can find out tonight. Still waiting for my boost gauge to show up, but I can just move the sensor.

 

[wrcknkrw]

Mine is a lly. No waste gate due to it being a vvt.

 

[plowboy_lbz]

My truck runs in the high 40's for boost but will occasionally spike above 50. My egts just touch 1500 then fall back to 1400.

 

[danzick]

How much boost is the 75 putting out?

Well, I took it for a quick rip this afternoon. Using my horrible to read edge digital gauge, I know it spikes to 22.5 looking back into the records, and it seems to nail 22 right after it spools, and drops to 19-20 after the rpm's get up high. This was only in 4th gear tho. I locked out OD because its still early in the day yet and I didn't want to be doing 90 MPH. and just to be clear, this is from the where you see the little brass plug in the tube between the 2 chargers. Thanks for the help everyone. Let me know what that tells you.

 

[mike diesel]

Your getting 22 psi from the s475?

 

[danzick]

im getting 22 PSI measuring after the 75 and before the stocker so I assume thats how it works?

 

[mike diesel]

Thats a good bit from that s475.

when I had an s475/modified hx35 twin setup on my cummins, I was only getting 12 psi from the s475 and could peg 60 psi boost gauge for total boost.

 

[03_DMAX]

I see 45 psi total and see 1300 degree max

 

[danzick]

Thats a good bit from that s475.

when I had an s475/modified hx35 twin setup on my cummins, I was only getting 12 psi from the s475 and could peg 60 psi boost gauge for total boost.

so im wondering if I get a good regulator for the stock gate and get it set right it will pass less drive pressure onto the 75 and keep more on the stock one?

 

[plowboy_lbz]

I think your ratio should be 1/3 (s475) atmospheric and 2/3 ( stock) high pressure. Did you talk to kory?

 

[Chevy1925]

so im wondering if I get a good regulator for the stock gate and get it set right it will pass less drive pressure onto the 75 and keep more on the stock one?

Yes