Boost surge after moving to 5300 ft

[TurboTnZ06]

Well, I just drove the Turbo T from Dallas, Tx to Denver, Co. In Dallas, the thing ran awesome, surge was not noticable. Spool time became minimal after a 9/11 PTS 3000 stall converter was installed. Now in Denver, I'm getting A LOT of surge at part throttle. At full throttle, I get the desired 17 psi boost in street trim. I tried backing off the wastegate rod, which did the trick for part throttle, but then I could only get 12 psi boost at full throttle after I got the part throttle to behave like it used to in Dallas. I'm running a TE44 (.63 Garrett) feeding a V4, ported stock heads and 210/210 biller roller cam and 50# injs.

One thing I haven't checked is if there is a herd of hobbits living in the cavernous dual SS ATR 3 inch exhaust...hmm that could be causing air flow problems...

Anyways, I ordered a RamChargers elec boost controller. Should I have a new chip burned for this high altitude dilemma or does the compressor map on the turbo need to be different? I'm thinking I'll just buy a TE63 and put my TE44 on ebay.

What setups are you 11 sec guys in Colorado (or >5000 ft) running and is this a known problem?

Thanks!!!

 

[Donald McMullin]

Your pressure ratio has increased with the change in altitude.

Example: (without the impact of temperature) assuming a boost pressure of 20 psig.

[1000ft elevation], Barometric Pressure = 14.16 (@70*F)

PR = (14.16+20)/14.16 = 2.41

[5000ft elevation], Barometric Pressure = 12.22 (@70*F)

PR = (12.22 + 20)/12.22 = 2.64

If you look at compressor map you will notice that as the pressure ratio increases for a set amount of mass air flow (#/min) you approach the surge limit (line).

You have two options, increase the low rpm VE of the engine or slow down your boost buildup. The latter of the two will be easier.

You can have your chip changed to provide a slower boost buildup. Ramchargers boost controller is a good product, but I do not think this will solve your problem of compressor surge, in fact this might make it worse.

As you noted, moving to a slower spooling turbo might be the answer. I am not sure about a TE63 because I have never seen a compressor map for this turbo.


Deep Enough
Donald McMullin

 

[TurboTnZ06]

The compressor map, that's what I suspected. And the TE44 was great at sealevel too I guess I can't ebay it, cuz I'll need it when I leave the front range one day. Guess I need tp order a PTE63 with a custom map for 5800 ft elev:-0 Thanks.

 

[Donald McMullin]

Before spending the money on a new turbo, I would look at having a chip made with a revised boost curve. To take advantage of a revised boost curve (in the chip) you would not be able to use the Ramchargers boost controller, its use will increase the boost at lower rpm's.

I would talk to Ramchargers or TurboBob (or any of the other major chip makers) to confirm this.

You can see what your chips boost curve is by using DS and reviewing the results.

Deep Enough
Donald McMullin

 

[TurboTnZ06]

New chip it is then Thanks. But I was looking for an excuse to go with a TE63 though...

 

[Eric Stage I]

The boost controller from Ramchargers has a useful feature that allows you to delay the activation of the boost solenoid. On the back is a small dial that adjusts at what throttle position the solenoid is activated. This may help your situation.

Regards,
Eric