5858 low boost issue

[dvernst]

OK let's make this more basic than my last post. 5858 turbo with a HD actuator. Rjc flange with oversize puck on the 3" downpipe. Have fix header, and crossover leaks already, and have checked numerous times to make sure the puck is perfectly lined up over the wastegate hole. If I hook up the actuator to the wastegate assembly with minimal tension, and take the vacuum hose off of it I only am getting 11psi boost. Shouldn't it go higher? The more I tighten it the higher the boost goes, but I don't have the vacuum line hooked up. I have to have to tighten the actuator rod about 11 full turns to get up to 26-27 psi,and that's still with no line hooked up.

Any ideas?

 

[Chuck Leeper]

Not a hd actuator? @11#, sounds like the range for the stock type....

 

[dvernst]

Not a hd actuator? @11#, sounds like the range for the stock type....

I'll check it again tonight. I have checked it. It would be great if that's it.

 

[dvernst]

It's definitely a HD actuator. Part # 1011-144

 

[TTA976]

Hi, get rid of the HD actuator. Preload is way too much. Get a the standard actuator. Light preload and light spring in the MBC is the way to go at our boost range.


Joe

 

[dvernst]

Hi, get rid of the HD actuator. Preload is way too much. Get a the standard actuator. Light preload and light spring in the MBC is the way to go at our boost range.


Joe

I'm running 27psi boost, and have to have the HD actuator cranked super tight to get it there. Why would I go to a standard actuator?

 

[TTA976]

The standard actuator and a Hallman MBC will cover 27# no problems...
Preload is way too much for 27# with HD actuator ... My boost is set 27# too. Use a Hallman MBC and stock actuator... Pull the rod about a 1/8"...run one line from the compressor nipple to MBC, and from MBC to actuator. No T fitting...Adjust the boost upward from there.

That pulling of the HD wg rod 1/2 inch to achieve desired boost is 80's technology.

Gimme a call if you want.... You can pm me your number.

Joe

 

[dvernst]

Right now if I put the HD actuator on with about an 1/8" of pre-load, and I take the vacuum line completely off, it boosts at 11psi. So explain to me how going to a lighter spring, and hooking the hose back up with a mbc will get me 27psi. I get 11 with the actuator holding the wastegate closed.

 

[TTA976]

Regulating boost with cracking pressure is old news.

A mbc regulates the pressure that makes it the wastegate.

Imagine you are running the "cracking pressure" of the wastegate, that means the Wg will be just opening, and not really flowing any exhaust gas. So imagine low back pressure at normal boost levels so the WG poppet valve doesn't get any extra help to open the spring, but to regulate the boost the WG will need to open beyond "cracking" and it will possibly run more boost.

Joe

 

[dvernst]

OK, but going to a lighter spring will not make the boost go up. If it's opening at 11 psi with a HD actuator a standard actuator isn't going to hold it closed

 

[dvernst]

The actuator is not hooked up

 

[TTA976]

I don't know how it doesn't make more than that with no vac line on the wastegate it should spool to the moon....

Guess I don't understand the question. What is the problem?

Joe

 

[TTA976]

The wastegate should never open if there is no line connected to it

 

[TTA976]

Just remember... Preloading the actuator is a bad idea because it con
siderably reduces the travel of the wastegate flap, and causes high EGTs on top of reduced efficiency.

Joe

 

[TT/Ameasap]

Call Joe. He knows his turbo's. he's like a mini Bison..lol

 

[dvernst]

I don't know how it doesn't make more than that with no vac line on the wastegate it should spool to the moon....

Guess I don't understand the question. What is the problem?

Joe

That's exactly the problem.

 

[dvernst]

I have the wastegate hole ported to 1.1 inches. I measured it with a dial caliper tonight. It has an oversized puck. I'm thinking of getting a new turbine housing, and a standard size puck. I've pretty much eliminated everything else that could be the problem

 

[dvernst]

This was last nights test

 

[Chuck Leeper]

This was last nights test

What are we supposed to see, in that pic?

 

[dvernst]

I pressurized the whole Intake side to 20 psi to make sure there's no leaks.