May be changing the setup again...

Extended Power

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After fighting with the truck for over two and a half years, I finally stepped back to a combination that was a dyno/track proven, 800rwhp.
With only getting to drive the truck twice before the transmission let go, I have decided to step it back a bit further.
I have been running one of the new Borg 69/73/.90 SXE turbos as my secondary since I switched to hybrid injectors. (About 2 1/2 years.)
For a street fighter type application, this would have been ok, but I'm slowing down, and just want to enjoy driving my truck to the races, and car show. No longer will it be run down the quarter.
I have a pile of parts that I want to use, just to clear out my shop, but if I'm going to pull the engine one more time, I thought I'd ask for some advice:

-Swap/sell/trade the 69/73/.91 for a 63/68/.70?
-Sell the 0.020" pistons that have valve reliefs, and ceramic coating, for a set of 0.020" de-lipped coated piston set, or just buy a set of rings, and be done?

-Who has the complete seal/o-ring sets for a fair price?

-Any other considerations? 6.4L rockers?
 

Extended Power

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I went back to 285/100 conventional injectors with dual hpop's.
I have a Chris Straub cam and lifter set to go in.
 

sootie

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I went back to 285/100 conventional injectors with dual hpop's.
I have a Chris Straub cam and lifter set to go in.
Don't just throw that cam in.....check the clearances

Unless you have reliefs already I can't remember.
 

Extended Power

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I sent Chris an email yesterday asking about the cam timing, and where he wanted it to be.

I have a friend who installed a Straub cam in his duramax, and it ran like poo because the valve timing was off.

I have been running a Colt stage two since they first came out.
 
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Zeb

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I sent Chris an email yesterday asking about the cam timing, and where he wanted it to be.

I have a friend who installed a Straub cam in his duramax, and it ran like poo because the valve timing was off.

I have been running a Colt stage two since they first came out.

I was really excited about Chris’ cams when they came out, but after running a number of them I’m very disappointed.
Power was always down, spoolup suffered, and most of them had exhaust valve clearance issues.
I had one in my wife’s Excursion and hated it. Swapped in an RCD Stage 1 with no other changes and pick up 35hp and 125ft lbs at the peak. What was really telling was between 2,200 and 2,400 rpm it picked up 102hp and 235 ft lbs. Guess which one was more fun to drive.
Since the RCD Stage 1 I have put a Colt Stage 2 in and it is my favorite. I would keep it if I were you.
Go to a stock 6.0 piston without valve reliefs, and at the most, just roll the lip back but don’t totally eliminate it. A straight bowl wall, and valve reliefs, tend to cold smoke a lot worse.
285/100 conventionals and dual hpop’s are quite a bit of fuel for a 369. I would not go smaller on the turbo with those injectors.
 

Extended Power

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I read an old thread about you having installed the Straub cam back in 2016 iirc.
Thought you were happy with the cam swap...better mpg too.

Can't seem to find any information on these cams anymore....and they aren't listed on his website, that I can see anyways.

The 69mm is fed by a 91mm...lotsa air...just need it in the right place at the right time.
 

Zeb

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Read my thoughts on your other thread.
I knew you had a 91mm Garret on there, but somehow got the idea you were going back to a single turbo, my mistake.
Are you wanting quicker response down low, and lower drive pressure up top? I don’t think a cam is really going to “fix” those issues.
In my experience, turbine wheel and turbine housing choice has the biggest influence on spoolup within a given frame size. I’ve run a bunch of the SXE 62, 63, and 64.5’s on trucks ranging from 400-600 hp, all with the 68mm turbine, and either the .83, or the .91 T-4 housings. I’ve not used the 73mm turbine, or a T-3 housing.
Smaller than the 64.5 I don’t see much point in running the 73mm turbine IN MOST APPLICATIONS, and the 64.5 you can go either way with the turbine depending on the application. I don’t think the 68 mm turbine is a good choice for any diesel application on the 66 and 69.
 

Extended Power

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I agree, the 68mm turbine is too small for anything over a 64mm compressor wheel.
The most responsive turbo I have ever used, was a 63/68 with a gated .70 exhaust housing.
From a dead stop, the truck could lay rubber until I backed out of it.
I also have a stainless steel, gated .80 housing for the 73mm turbine wheel on this 69mm.
Even it worked better than the T4 .91 housing. (Of course...cuz it's smaller.)

The only turbo that had a perfect 1:1 ratio, drive to boost pressure, was the one hit wonder from......gawd I can't remember his name right now...
Anyways, it was a 64/71 with a non-divided .70 housing on it. It held that 1:1 ratio right to 40psi, then it started to wonder off.
I'd try that one agin too in a heartbeat.
 

Zeb

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It wouldn’t have been Bell Turbo, would it?
I think the 1:1 boost to drive ratio gets stressed out about way too much. I tell guys it takes 2 things to make a turbo spin, heat and pressure. Gotta have them both, within reason.
Are you running an external gate, along with a gated turbine housing?
 
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Extended Power

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Right now I'm running the .91 housing on the 69/73, and an external gate.
The gate dumps it so fast, I get a "wop, wop, wop, wop....." as long as my foot is planted.
If I tied it back into the hot pipe, it would be going up against say 50 psi. Where as right now, it just dumps to zero pressure. (Atmospheric)
The gate has the best flow priority, divided equally by both up pipes, tee'd into one port.

If I keep this 69mm I'm going to either put the stainless steel housing back on, or get a single scroll .70 housing for it.
 

Zeb

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Is there anyway that you can control the gate to open more progressively, instead of all or nothing?
It’s fairly common on the higher powered Cummins stuff to gate from the manifold into the intermediate pipe.
If you wastegate exhaust from the manifold to atmosphere, it’s going to be terribly hard to get enough exhaust flow thru the high pressure turbos turbine wheel and housing to properly drive the primary turbo.
 

Extended Power

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I know...I just never had the time to add the piping....was always fighting with the tuning.
I knew it had to be done, but it was the easiest way to at least get the truck back on the road.
Cory, with Straub Tech, sent me a cam card, and install instructions.
At least I have what he wants to see as valve timing on the intake and exhaust now.
 

Zeb

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If you decide to try the Straub cam, please keep us posted on how it goes when you degree it. I’m really curious about this.
I told my wife I was gonna make a leg for a coffee table out of it and several destroyed stock cams I have. She said I wasn’t allowed to!
The best thing I ever did with mine was send it to Geoff at Colt and have it reground to his Stage 2 specs. It works a lot better now.
Thankfully several of the guys that had bought them from me hadn’t installed them yet, and I’m having them reground also.
These cams have cost me a lot, but I couldn’t stand the thought of guys hurting their motor with parts I promoted, and Chris won’t admit to anything being wrong, so.......
 

Extended Power

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Yeah, I found a thread on YB about him....not good.
Well chit....now what do I do with this damn thing?
I already have a stage 2 from Geoff.
 

Zeb

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Personally, I’d keep the Colt Stage 2, plumb the wastegate into the intermediate pipe, and play with wastegate “tuning”.
You’re drive pressure to boost ratio really isn’t out of line, and with some refinement I think what you have will work even better.
I know this doesn’t address your concern of soot in the intake manifold, but I wonder if the wastegate opening and closing over and over doesn’t cause drive pressure spikes that cause that to happen.
 

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