travelor
Pro
I have a turbo xs controler and blow off valve. I think they are anyway. My controler somestimes gives me over 20 lbs boost when set around 17. When I turn back down and up again, it will be ok again. Tried lenghtening waste gate arm thinking I could set it not to go over 18. Thought I had it but then It spiked up again. Should i get an electronic controler to solve problem. When I go up in altitude I turn up boost to compensate for the deeper snow ect. Another idea is to get the new mcx box that is suppose to keep power the same. As you go up in altitude it will raise your boost pressure. It is #1000. bucks. The mapping may be better as well. On the blow off valve, how many washers should I have in there? Was worried about loosing boost with not enough pressure. Thank you for any advice. I am hoping to get all my problems from the last two years solved for this year. This is on a apex mountain.
If it is a real turboxs mbc it shouldn't spike that high. It's hard to find any boost controller that won't spike a little ~ 1-2 psi. I had a Turbo xs on my car for over 2 years and it never spiked over 2psi. If it is just spiking (going to 20 psi for ~.25 sec then settles down to your desired boost pressure) I honestly would not worry about it. That spike will not hurt anything unless it takes a substantial amount of time for it to settle down to your desired boost pressure. I don't see any reason to spend any more then 100-150 for a good mbc (manual boost controller). Certainly not $1000. Hallaman makes some of the best. A electron boost controller is not going to save you from a little bit of spike. You can still get spike with a electrical boost controller. I had a Gready Profec that spiked just as much as my turbo xs mbc.
As for the BOV. I think it is smart to keep them as soft as they will go. The more you stiffen them up, the more prone you are to compressor surge. Just because it's set soft does not mean it will leak boost. You can varify this by doing a boost leak test while setting it at it's softest postion.
All that being said, I would make sure you have a genine Turbo xs mbc, and bov. Especially the bov because the knock off's are natorious for leaking.
As for the BOV. I think it is smart to keep them as soft as they will go. The more you stiffen them up, the more prone you are to compressor surge. Just because it's set soft does not mean it will leak boost. You can varify this by doing a boost leak test while setting it at it's softest postion.
All that being said, I would make sure you have a genine Turbo xs mbc, and bov. Especially the bov because the knock off's are natorious for leaking.
travelor
Pro
I guess I should test the blow off valve but have to install the intercooler to test and remove again to change it. Too hard to get at. My controler doesn/t just spike , it will stay up high until turned down. If I get around 16 or 17 lbs. It will sometimes jump to over 20 and stay there. I may buy the new 1000 dollar computer box to solve the fuel issues. But still will not be able to control boost without adjusting waste gate rod or using the manual controller again.
hlmrx1
TY 4 Stroke Guru
I thought the purpose of the blow off valve was to release the presuure when you let off the throttle and the slides close. If so then it should not have anything to do with boost spike. Mcxpress could be different than Powderlites I guess.
travelor
Pro
Yes I was asking about two different things. Thanks
rxrider
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travelor said:
You may have a leakage and/or restriction in the line going from the outlet of the MCB to the wastegate causing overboost. If the line is leaking or restricted less pressure is reaching the wastegate causing it to open less than it should.
My friend were struggeling with the exact same problem as you are (MCXpress rearmount). He checked and rechecked all lines to and from the MCB, he was absolutely positive that he had checked every line and hose clamp there was, but it still peaked at 20 lbs and holding. I told him that there had to be a leak somewhere, and it was, the hose going to the wastegate was leaking at the wastegate inlet. We changed out the hose clamp to a new slightly bigger one, and that cured his overboost problem.
We both run Hallman Pro RX MCBs with good luck, they do not spike in the MCXpress rear mount applications, we're both running 16 lbs of boost.
travelor
Pro
I didn't have an external leak that I could find. Buddy had same problem, cleaned out valve and may have fixed it. I just don't want to keep having that problem. That may be the reason my header pipes cracked from temperarily getting lean.
TurboJamie
TY 4 Stroke God
hlmrx1 said:
When you have a turbo that spools really really quickly it can overboost the system, which is why we need the wastegate to dump as quickly as possible. The BOV should remain shut until the throttle is released.
Need for Speed 2
TY 4 Stroke Junkie
all manual contollers will allow boost spike or creep you dont realize how much the gate is dumping before the desired setting until you install an electronic controller. i run the E=boost2 it spools till the desired setting and then theb gate opens.
