boost creep/spike
06-13-2009, 11:57 PM
#1
boost creep/spike
I've noticed that now that I've put sevral miles on this new setup that when I roll into the throttle the boost just wants to keep going up... my AFR doesnt fall correctly in those cells in the VE either so this can potentially be a bad thing LOL... I know the WG is opening because I can hear it. Its vented to atmosphere under the cab of the truck LOL... it went WAY farther than it should have, lets just put it that way.
Its a 38mm TiAL wastegate with a .5bar spring on a front mounted Precision 78mm turbo on a KBracing kit with all 3" cold side piping, 3" DP, and 4" from there back. This same exact setup only ever made at very most 6.5psi on my 5.3L with MP T-70 and did the same with the first 347 setup (minus the 4" exhaust)... now that this turbo is on, it is creeping and spiking... I know many people running MUCH bigger turbos with a single 38mm WG... what gives...
-could the reference line be too small???
Its a 38mm TiAL wastegate with a .5bar spring on a front mounted Precision 78mm turbo on a KBracing kit with all 3" cold side piping, 3" DP, and 4" from there back. This same exact setup only ever made at very most 6.5psi on my 5.3L with MP T-70 and did the same with the first 347 setup (minus the 4" exhaust)... now that this turbo is on, it is creeping and spiking... I know many people running MUCH bigger turbos with a single 38mm WG... what gives...
-could the reference line be too small???
06-14-2009, 02:38 AM
#6
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i dunno but the tial rep told me the lower amount of boost you run the bigger wastegate you need, i asked if 44mm would be big enough and he said no u need a 60mm i guess it gives it better control over the system, but i dunno just going off what he said..
06-14-2009, 05:52 AM
#7
That 38mm is fine on the engines, and your venting to atomshpere so that even helps it flow better. You mentioned this problem has just started happening so
Take a look at your reference line, any small hole / leak can and does cause issues. Also if the diaphram got damaged again with a small hole. Or if using a rubber line and if it has gotten spongey may cause this.
I think the best way to set up a reference line is by using hard tubing. Yes its a pain in the back side but, you do not have to worry about holes, hose expansion, heat etc.
Take a look at your reference line, any small hole / leak can and does cause issues. Also if the diaphram got damaged again with a small hole. Or if using a rubber line and if it has gotten spongey may cause this.
I think the best way to set up a reference line is by using hard tubing. Yes its a pain in the back side but, you do not have to worry about holes, hose expansion, heat etc.
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06-14-2009, 08:21 AM
#8
Yeah, right now its 1/4" rubber hose. Its always worked fine, might have just developed a leak like you said. The WG diaphragm looked brand new when I took the top off to inspect it and verify the spring in it. Ill replace it with nylon tubing, should I step it up in size while I'm at it?