ONLY 15#'s OF BOOST

[BIGAIR]

Hey all,

OK, so I got a 70Qtrim turbo from a friend to replace mine. No matter what I do, I can only build 15-16#'s of boost. The RJC controller is as tight as I can get it(shorter overall), I even removed the set nut so I could set it tighter. I tried a very heavy duty spring in the controller as well. Then I have the wastegate rod so short I can barely put it on the puck rod. My friend ran 26# of boost with this turbo and wastegate. I thought of trying my wastegate, but it will not bolt up to this bigger turbo. Can I remove the RJC controller and run the line straight from turbo port to wastegate and try using only the wastegate rod to adjust boost? Any other suggestions would be appreciated.

TIA,
Lee

 

[BIGAIR]

ANYONE,
any suggestions?

 

[Junior Samples]

CFTB club member Dave Wick's wife ran a mid 10 on 13#s with that turbo putting the stomp to a nissian skyline

Anyway check your wastegate puck for fitment, recheck for leaks around headers. if you run tuner style with vac line from comp to wastegate i think it will only pull 14#s..not sure though, never tried , never needed to

 

[SGRIM]

What are you using for a w/g? Also check for leaks as mentioned above... If you are using stock setup it will only go that far. You need a HD actuator!

 

[jasjamz]

The turbo has a hole in the exhaust side that may be off center to the puck in your down pipe. It will slow down spool up and bleed off exhaust, thus not allowing you to get the boost up past where you are now.

 

[gczarny]

Hey all,

OK, so I got a 70Qtrim turbo from a friend to replace mine. No matter what I do, I can only build 15-16#'s of boost. The RJC controller is as tight as I can get it(shorter overall), I even removed the set nut so I could set it tighter. I tried a very heavy duty spring in the controller as well. Then I have the wastegate rod so short I can barely put it on the puck rod. My friend ran 26# of boost with this turbo and wastegate. I thought of trying my wastegate, but it will not bolt up to this bigger turbo. Can I remove the RJC controller and run the line straight from turbo port to wastegate and try using only the wastegate rod to adjust boost? Any other suggestions would be appreciated.

TIA,
Lee

what is your exhaust system ? still have cat on it maybe ? low flowing exhaust will limit boost levels with big turbo like that , I put spiral muffler at one time to quiet down my exhaust ,oh it quiet it down nice but I had problem building boost over 15 psi .

 

[BIGAIR]

Thanks for replies,

Have a HD wastegate, checked to see if the new wg held vaccum w/ a mighty vac., it held vac. at 22 w/o any leakdown. tested my old wg w/ the same results.

I will check my puck fitment today. I thought of that, but when driving, the spool-up is not too bad for this turbo. It just won't go above 15#'s

My exhaust is a 3" single w/o cat, turn down at rear diff. Although it does have 3 flow through spiral type mufflers in line. MMMMM......My friends exhaust is a traditional GN style w/ Magnaflows.
Possibility.

BTW, I did remove the RJC and only got about 14#'s. So, my problem IS elsewhere.

Thanks guys,
I'll keep you posted on findings.
Lee

 

[gczarny]

Thanks for replies,

Have a HD wastegate, checked to see if the new wg held vaccum w/ a mighty vac., it held vac. at 22 w/o any leakdown. tested my old wg w/ the same results.

I will check my puck fitment today. I thought of that, but when driving, the spool-up is not too bad for this turbo. It just won't go above 15#'s

My exhaust is a 3" single w/o cat, turn down at rear diff. Although it does have 3 flow through spiral type mufflers in line. MMMMM......My friends exhaust is a traditional GN style w/ Magnaflows.
Possibility.

BTW, I did remove the RJC and only got about 14#'s. So, my problem IS elsewhere.

Thanks guys,
I'll keep you posted on findings.
Lee

you say 3 flow through spiral mufflers so one of them is in place of cat ,is it not ? remove that one only and retest .

 

[salvageV6]

Check for a leaky intercooler hose I had a leak once that gave me a rock solid 17psi. boost when I was shooting for 25.

Sometimes they leak on the bottom side of the hose even though the top looks like it's on good and tight, check for splits too in the neoprene liner.

 

[BIGAIR]

Checked and DBL checked all connections and hoses. Zip tied and hose clamped everything that could use one.

I did take out the last section of my exhaust, the turn-down. It is about 36" long and narrows slightly smaller than the muffs. (where it clamps to muff), probably 2.5", then widens again to the exit if 3". So all 3 flow throughs in-line, no cat. Went for a run........YEAH BABY!!!!! 23#'s. Car felt good, but I let off early as my A:F were 12.5:1, EGT 1565.
Now I need a quieter exhaust....any suggestions? My son said it sounds SICK, (he's 13) I think a BUICK should be more quiet than this. It sounds like Donnie W.'s video on You-tube, but that car is BADA##. Maybe If I could get it to run like that, I'll keep it loud

Thanks for all the help everyone!
This forum kicks A##