I have a 99 auto with banks turbo outlet, straight exhaust, edge jucie attitude with cs monitor, ddrp, brute intake. My old mans truck is a 01 6 speed with the same stuff on it but with the cts monitor but full exhaust. My question is my peak boost is 28 his box is set a 30 max boost and im already seeing 31 psi why is his truck making more boost than mine? I have heard that the manuals had a bigger turbo? Another question is what can i do to get more out of my turbo or should i go bigger turbo or waste gate?

Thanks

 

Some autos got the hy35 which has a slightly smaller housing than the hx35 that all the manual transmission trucks got. Smaller hy spools slightly quicker, but is limited on max boost due to "choke point" to around 30 psi before becoming inefficient and causing egt's to climb.

I wouldn't bother trying to get more out of the turbo if it's giving you 28 psi. I'm guessing you are reading intake pressure, and upstream the turbo is probably creating a few psi higher than that anyhow, which means it's at it's limit.

As to wastegate, if you are making 28 at the manifold, your waste gate is already modified (banks "power elbow"?).

Next step if you want more than you have would be a hx35 if you can find one cheap, but it won't give you that much more. Or time to think about a bigger turbo. If you have a stock converter, I'm surprised you haven't smoked it already. Guess the 4.56's are buying you some leeway.

 

Both trucks have the HX35 on them.

 

X2, it's only the 01 02 auto's that have the hy. Could be the waste gates are just a little loose to tight one compared to the other. And every truck is a little different. Is one h.o. vp?

 

Not all wastegategate diaphrams are identical, neither are boost elbows & gauges for that matter.
You can tune it it with and adjustable boost elbow.

All here are good ones,
http://motors.shop.ebay.com/i.html?_...=&_trksid=m270

 

yes the 2001 is a high output 6 speed truck

 

There it is, I'd say that's the number one reason all is the same but boost lbs.

 

Boost leak issues with one of the trucks, one of the gauges might be out. The HO truck uses a different VP than the auto. The HO runs a 028 VP pump and the auto runs the 027 VP pump.

 

Factory boost setting for standard output Cummins '98.5 - 02 was 19psi and for the '01-02 HO it was 26psi.

 

That big of a difference between an SO truck and a HO truck?? 19 psi and 26 psi? That seems like a huge spread