stumped with boost

L

Ls10

New member
I have a brand new holset hx35 with .76 ar housing. I also have a tial 38mm wastegate. I had a 14.5 psi spring in for a while and it was right about there on the gauge. I had zero knock. never saw it come off 0 once. I decided to put a 16 psi spring in and noticed its only boosting to just shy of 15. so just to test I put a 17 psi spring in. and its 15 psi on the button. but now im seeing 5 or so degrees of kr. how could only .5 psi cause that and why wont it go above 15 psi. I checked for boost leaks and it all seems good.

I do have the wastegate ref about 10 inches before the tb. afr is 10.6-10.8
 
Last edited:
dgoodhue

dgoodhue

BuSTeD 4.3
Re: stumped with boost

Maybe it isn't reaching 17psi because the ECM is pulling timing. or the reason why its pulling timing is affecting your boost level. As the engine pulls timing your exhaust pressure might be lower so that it doesn't have enough exhaust flow to spin the compressor fast enough. [I would assume your 38mm waste gate is starting to open a little by 15psi)

17psi on the stock motor and pump gas could be beyond the boost level that it will not detonate. My stock motor never liked 17psi on pump gas. Some trucks will tolerate 17psi though. If you engine is pulling 5 degree at 15psi, it would be pulling even more timing at 17psi so that could be a blessing in disguise.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: stumped with boost

I would try to troubleshoot your knock retard and see if the boost increases after that. I am guess you don't have a boost controller or the factory boost solenoid hooked up to the external wastegate.

Do you have any datalogs?
 
L

Ls10

New member
Re: stumped with boost

dgoodhue said:
I would try to troubleshoot your knock retard and see if the boost increases after that. I am guess you don't have a boost controller or the factory boost solenoid hooked up to the external wastegate.

Do you have any datalogs?
Click to expand...

no just running on springs. I ordered a boost controller because after dicking with it I put a small hole in the wastegate hose by accident and it went to 19 psi then I let right out. so I know its capable of going over 15 haha. I don't even know where to start with figuring out the kr. only thing I changed was the muffler. went from a flowmaster that came with the truck to a magnaflow. im putting the original 14.5 spring in and if I get kr I know something is up because I never got it to budge off 0 with that boost. arf at wot is on the rich side 10.2-10.5 so I know its getting fuel. is there a way to mess with the timing aside from the dist?

im also still having temp issues. running a new rad,new 160 tstat,new water pump,new intrepid fans,yet if I do a pull through a few gears it will get to about 200 degrees,and it takes forever to cool down. the fans constantly run. then when I get on the highway with the fans on or off it creeps up. I built an air dam behind the grille to help channel the air in,it helped but still creeps. other than that it runs amazing. if I drive it easy and keep it under 40 stays nice and cool and runs great
 
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