turbo boosting question

[BuickTV6]

hey guys this is probably a really stupid question but here goes.Since i got my tranny rebuilt, I notice my turbo boosts almost all the time in low gears, even just when touching the gas. Which is no big deal cause of the extra power it makes.. But when on the highway especially when really windy, it usually boost 1 - 3 psi going 60 mph, Rpm's are at about 2200. I usually drive slower then this so it never boosts. But this weekend I took it on a little car trip, and was cruising anywhere from 60-80 mph. When going that fast the turbo was hissing its lovely song at about 4psi, and wouldn't boost less than 2 psi with cruise control on or off.. Ive never driven this car so fast for such a long time is this normal? Am I risking burning the turbo out driving that fast for an excessive amount of time? Any input would help.

Later, Todd

 

[b4black]

Did you change the stall of the torque convertor? Was the rebuilder familiar with Turbo Regals, or just a typical trans guy?

I think you want to avoid being under boost for long periods of time.

 

[WFO]

is this on an aftermarket boost gauge?

 

[6SENSE]

I dont know, might be nothin wrong here. One thing to understand is that the turbo is always going, as long as the car is running and air is going into it and exhaust out, it is spinning. Its not like the turbo turns on when you get on it, its not that complex. Its mechanical, not electric. I remember when I was younger I used to think that turbo boost was something that you press a button and all of sudden your going "turbo speed".
Any time you are putting a load on the engine you will see boost building on the gauge. Its real interesting (and good learning) to see how it goes on a gauge that shows vac and boost. If your on level road or going down hill, and not getting on it (just cruising), you will naturally have more vaccum. If your on level ground and on it a bit, or traveling upward on a inclined strip of roadway you are putting more load on it and the vaccum will go down and you will see boost climbing on the gauge.
2200 rpm sounds about right to me cruising on the highway in OD. What I would be interested in to get sort of a basis of where your starting with your vac/boost is what type of vaccum is the car producing when sitting still (in P, and in D). Not saying there definately isnt a problem, but just that there are other variables here to look at. WFO asked a good question, this isnt the stock gauge your going by here is it? Also, with regards to what I mentioned about putting a load on the engine, how heavy is your foot?

 

[BuickTV6]

This was on an aftermarket boost guage. Suprisingly enough my factory guage is quite accurate compared to the aftermarket one. The factory one seems accurate for me up to 10 psi, then it starts going off. And yes, on inclines, i notice the boost come on, and i can hear it whistling. I understand that the turbo wheel always spins, but what worry's me is having it spinning under boost for an extended periods of time. It does the exact same thing with cruise control on and off. The transmission has a 2800 stall lockup convertor in it, and the guy who rebuilt it knew his turbo regals. He was actually a guy who knew the hotairs better then the intercooled ones. Could the higher stall do this? With the stock tranny, I dont ever remember it boosting so much at all. I remember it being more sluggish on the hwy too. I dont mind the boosting at all, but I am a little of a leadfoot, and i usually drive the car around 70-80 mpg on the highway. I just don't wanna burn the turbo out frome xcessive boosting. Thats all.

Later, Todd

 

[b4black]

I have a high stall converter and I'm sure it runs on vacuum, not boost, down the highway. I don't know the exact amount - it's hibernating. Maybe someone's driving everyday can tell you what they see.


I'm 95% you don't want to be under boost all/most of the time. That's why you don't tow anything with a turbo car. (The extra weight/load causes you to run under boost too often.)

 

[6SENSE]

I also have a 2800 lockup. I havent driven my car for a while, but as I said before, that 2200 rpm does sound about right in OD.
Do you have any idea how much vaccum your car is getting sitting still? Not exactly sure, but Im thinking if you have low vaccum for some reason (i.e. a vac leak, or bad cam) to begin with, your that much closer to being on the boost side right off the bat. For example, if your at 8" vac in Drive your only going down 8" to zero, then your on the pressure side (psi/boost). If your up in the 15"+ vac range your that much further from pressurizing to begin with. Someone let me/us know if this sounds right.
May want to post your question in the General Tech section too.

 

[Matto]

boost

Mine down the highway at 75 or 80 is still in vaccum 8-10psi unless I hit the gas a little harder to pass, then it goes into boost. Matt Wenning

 

[TType84]

i think your gauge is jacked up..


somethin is weird.. shouldnt have any boost unless you get on it, if im going highway speeds and let off the gas, as the car slows itself down the vac hits 20".. i suually have about 16-17 in park and 15 in gear stopped.

 

[BuickTV6]

I'll have to check the guage out. Maybe swap it with another one to see if I get the same results. I can tell its boosting though cause i can hear the turbo whistling. I tried it again last night, took her up to 0ver 80 mph. Rpm's were around 2500 and the boost was staying off for the most part. Ubless i was going up on an incline. The wind was in my favor so maybe that had something to do with it?

 

[Nocooler]

I have noticed this with the Turbomotion V-2 also. For some reason with a small turbo - it was never below 5" of Vac @ 70+mph. With a head wind extra load would make the boost rise. @ 80mph I was always blowing boost.

 

[BLACK Ttype]

Our cars are not very aerodynamic. Therefore alot of head wind will cause an extra load on the motor. I get it all the time on the highway.

 

[BuickTV6]

Thanks for the help guys. i'm pretty sure it is that too, Was just wondering if anyone else saw this in their cars. Thanks for the input

 

[cool 84]

On flat ground at less than 130mph you shouldn't see any boost or hear the turbo. I've literally had mine cruising at 120+mph with no boost. Even on steep hills it will do 65-70mph in OD with needle occasionally moving to ~1psi on the steepest parts. You're not going to hurt the turbo, diesel trucks pull 6+ psi on level ground for hours at a time. What kind of gas mileage are you getting? The only thing I can think of is tranny binding in which case it would already be burned up or timing very retarded. I'm curious about your gas mileage. What's the WOT power like?

 

[BuickTV6]

cool84

Well, im not sure what kinda miledge im getting, it seems pretty good to me. Its pretty well been the same since I bought the car. However, the tranny is freashly rebuilt, ive only put like 8,000 miles on it. It was since the tranny was rebuilt im noticing this. like first to 2nd shift if driving pretty easy on the foot it'll boost 2-3 lbs. unless im just touching the pedal which is usually too slow. From 3rd gear to o/d, the shift is usually delayed a little, when it shifts into O/D it'll boost 3 psi or so until u let off, then its fine. It seems like the motor is relying on the turbo a lot for that extra boost. With the stock tranny, i wouldnt get boost unless i laid into it 1/4 or more throttle. if im cruising at 50 or 60 mph, i dont see any boost. But any higher then that it'll usually boost. I tried it yet again tonight and i was getitng no boost at 80 mph, granted there was no wind whatsoever. Rpm's were at like 2800 at 80 mph not sure if thats right. Wot power is pretty decent, i gotta work some bugs outta it tho. Cause it runs absoulity great when its cold, but on hot days it runs the craps. It also hesitates like a b***h off the line, and has a rough idle. i've changed sensors, adjusted tps, new maf, TB gaskets, checked for vacuum leaks. Still does the same thing. When i first start er up, she fly's, absoulity no hesitation at all. runs like a top, chirps through gears. Once she warms up, she dont run near that great, in fact, if i floor it off the line, it either stalls, or falls on its face. I have no idea why this happens, nor do I know if this problem is related to this boosting issue.

 

[6SENSE]

Im trying to picture what your car is doing with this boosting issue. When you mentioned how it shifts, the one thing that came to my mind is the TV cable. Make sure it is adjusted properly. Might be the cause of your delayed shift. Plus if the car is shifting late, holding in gear longer than it should, naturally the boost will creep on you with the rpms.

 

[WFO]

Re: cool84

Originally posted by BuickTV6
It also hesitates like a b***h off the line, and has a rough idle. i've changed sensors, adjusted tps, new maf, TB gaskets, checked for vacuum leaks.

that intercooler kit must be a piece of sh!t.you should relocate your throttle body. .ok,i'm done being a smartass now.

Originally posted by BuickTV6
Still does the same thing. When i first start er up, she fly's, absoulity no hesitation at all. runs like a top, chirps through gears. Once she warms up, she dont run near that great, in fact, if i floor it off the line, it either stalls, or falls on its face.

it sounds like a tuning issue.looking at your combo the best $360 you could spend right now is on a 16 position maxeffort chip.your car runs good in open loop,but like crap in closed loop.with a maxeffort it's in open loop all the time,and you control all parameters.open loop idle at 900 rpm feels like a friggin sewing machine.you won't believe your car could idle and run that good.

later,sean

 

[Nocooler]

You should have little to no driveability probelms with the Turbomotion V2. My car drove flawless till the engine ate a compressor wheel (it was downhill from there).

My car with the V2 responded vary similar to an 86/87 TR - at high speeds the vacuum readings are gonna be very different than a hotair car. With the mods he has - a Ta33 is going to want to build boost at light load at about 2500rpm. Unless you have cruise the "all or nothing" TR gas pedal is gonna make it difficult to get the vacuum where you want to see it. Try your cruise?

Does you convertor lock-up? How much does the rpm drop?

If the convertor isn't locking your spinning a few hundred extra revs.......

 

[BuickTV6]

Thats actually a good point nocooler. I have absoulity no idea if my convertor is locking up. I've tried the gas the brake thing, and noticed absoulity no change whatsoever in the rpm's, or the sound of the engine. What is a good way to check to see if the convertor is locking up? what what kinda rpm difference should I notice if it is or isn't?

Later, Todd