To much boost...

[ENafziger]

Too much boost...

Well, I just got some DiPricol gauges installed Friday (EGT/Boost/Fuel Press/Rail Press). I know gauges are normally the first mod that should be done, but I'd been relying on the TST's boost/egt gauge and backdown features. Anyway, took the truck for a drive saturday, with TST on 5/5, to try out the gauges. Up the first hill, I gave it some throttle, and the boost gauge nearly pegged at 60 psi!!!



What happened to the TST backdown? Does the SPS66 spool so fast that the TST can't back off quick enough? How can I limit the boost a little?



On a positive note, the head gasket seems to have held these 60 psi boost spurts so far!

 

[MNewton]

Adjust the gate on the turbo to were you want it then turn off the backdown. It is better to use the gate on the turbo to limit the boost this way you will get full fuel on top without the TST backing down.

 

[JLibert]

I believe the boost limit (if you have the newer style TST) has to be turned to the off position, as it doesn't read anything past 40psi. What did you have the boost limit set to? The older style TST programs didn't have this feature.

 

[JVolpe]

Like stated above the TST read boost from the ECM and is limited to around 40psi, anything over that it does not see. My II SPS66 came with wastegate set at 50psi and I had it adjusted up to 55psi. I see spikes everyonce in a while that go above 55psi, but not often and never long. Just long enough for the wastegate to get open.



You need to check what your wastegate is really set at.

 

[ENafziger]

Thanks! I had the TST backdown set at 39 psi boost. Is adjusting the waste-gate pop off pressure easy to do on the sps66? I didn't realize these turbos would boost like that... Way to go II!

 

[Prairie Dog]

I dont think the wastegate is big enough to bleed off excess pressure at higher levels. If I set my TST to 6/6, it will peg the gage (50PSI) and keep it there even though the wastegate is wide open. I've only done this 3 or 4 times because I fear for the turbo!

At lower power levels the wastegate keeps up just fine.



Scotty

 

[JVolpe]

Call II and ask, don't think it is very hard. I had Michael at HotRodDiesels adjust mine since I have become old and inept at things mechanical it seems.



My wastegate once open will keep my boost around 55psi on FULL HARD WOT at the track. The autometer gauge just kind of vibrates around the 55psi mark at the track for most of my 1/4 mile runs. If I do a WOT from a roll the boost will spike past 55psi to 60psi until the wastegate opens and then drop back down.

 

[RobertP]

with that much boost i would watch out you may be floating the valves. i would adjust the wastegate down to about 50 psi.

 

[MNewton]

Thanks! I had the TST backdown set at 39 psi boost. Is adjusting the waste-gate pop off pressure easy to do on the sps66? I didn't realize these turbos would boost like that... Way to go II!

It is alot easier to take of the turbo to adjust gate when you get it off unhook the rod from the gate then preload the can to what pressure you want with a compresser with a good regulator. Then screw in the turnbuckle till it slides over the arm with the gate fully closed. It will start to open when you reach the pressure you set with the compressed air.

 

[JVolpe]

with that much boost i would watch out you may be floating the valves. i would adjust the wastegate down to about 50 psi.

Well I finally did put studs on and have started running with lower stack settings. I am afraid that I might have floated them a time or two, so far without catastrophic results. I am toning down the track time until next year and hopefully get to finish my mods. Pull the head and make sure no issues, then cam, springs, etc.