What's your boost threshold?

[barrygti]

Ok guys can we get a list of:

Engine
Turbo
Boost Threshold
Boost Level
Power if known

Might help some, including me, work out what turbo to use. Have a nagging feeling my Land Rover turbo will be too big.......  :lol:

[AudiVWguy]

How do you define boost threshold?  
Boost level--at a certain rpm and gear, highway, max boost? Just trying to understand what you want.
Thanks

[barrygti]

Yes, at what RPM do you reach maximum boost loaded in maybe 3rd or 4th gear?

[zukgod1]

Well my personal Boost Threshold is about 35 psi, beyond that I start to get nervous.  :lol:


But on a bit more serious level.

Personally I wouldn't take a stock 1.6 with a 24 over 30 psi and expect it to hold together long. The stress on the turbo will be less the higher you get using a larger turbo but the lag will be nasty, meaning @ 30 psi a 26 may be at it's limits before it blows up and a Garret T4 with say an 60mm compressor and a .48 exhaust can run @ 30 psi all day but your going to spool the 26 way sooner in the RPM range than the T4

Problem is we really need to be talking about CFM instead when we are talking about turbos. A k26 can run @ 25 psi as can a k14 but the 14 will be pushing HOT air and have to work much harder to get it.

Here's the problem as I see it.

Everyone here want's BIG boost, my self included. Then when we get it we realize it sucks! I just bought an 02 Passat with a gasser 1.8t (I know I know) and it has a k03 on it. Damn near the smallest turbo I have ever seen on a car this size but holly crap does it perform!

Now when I first built my car (jetta diesel)I had a stock k24 on it and it was fun, well that wasn't good enough for me I wanted more! I built a 26/24 hybrid and bolted that baby on, holly crap talk about power! But it was a DOG at anything under 3000 rpm.
Cruising down the freeway @ say 75 mph I was turning about 2700 rpm, if my cruise control tried to compinsate for a hill the smoke out the back would black out the freeway, that wasn't to good for economy not to mention I actually got pulled over and cited for it once.

Now had I been running a k14 the turbo would have lit and the smoke wouldn't have happened.

You need to decide (as we all do) what youwant/ need your car to do. Build from there.
In my opinion going with a turbo that is smaller than what you think you want is going to be perfect.


I'm rambleling now so i'm going to shut up.....

[zukgod1]

For giggles.

Smallest is an k03, middle is k24 larger is k26.
I should have put something there for size reference sorry.



The one in my hand is an exhaust wheel from a k24 the one in the housing is the k03

[barrygti]

What you have discussed is my great fear. I don't want to ring the neck of a smaller turbo as I believe it places more stress on EVERYTHING.

However I am worried my BV50 even with VNT will not start boosting till 3k rpm, maybe full at 3500rpm and be all done and over by 5k.

However I also don't want a 30psi hit at 1900rpm and have component killing torque.

Wish I could find a damn compressor map.

[andy2]

Excellent advice zukgod1  :wink:

[blackdogvan]

What you have discussed is my great fear. I don't want to ring the neck of a smaller turbo as I believe it places more stress on EVERYTHING.

However I am worried my BV50 even with VNT will not start boosting till 3k rpm, maybe full at 3500rpm and be all done and over by 5k.

However I also don't want a 30psi hit at 1900rpm and have component killing torque.

Wish I could find a damn compressor map.

Whats the disp, hp & tq @ RPM numbers from the engine that turbo is off??

[barrygti]

Whats the disp, hp & tq @ RPM numbers from the engine that turbo is off??

2.7 V6, 190bhp at 4000rpm, 325lb/ft at 1900rpm

I used to work on these vehicles and they do come in nice and strong so I am hoping the turbo is on the small side in order to increase torque due to being a 4x4.

[Smokey Eddy]

i find my t3 is too big for "fun" daily driving. But when i dont mind spending the extra money on diesel it will perform if i feed it enough.

Foot to the floor pushing 25psi PLUS it's quite the torque monster. but... driving around town you never get over 10 without really wasting fuel... driving conservatively but comfortably it [with my build] will make maybe 4-6 pounds?

just my experience...
your mileage may vary:)

[barrygti]

Is that the standard T3 you are running?

What sort of power/torque do you make as your engine is along the lines of what I am doing.

Do you use the standard 1.6 pump and injectors?

[g-spec]

Im currently running a T3 on my 1.9 AAZ peaks at about 30-35lbs. But my friend is willing to give me a t3 super 60 he has and Im gonna try and build that for my 1.9. I want to use the cold side from the super 60 and the turbine from the diesel t3.

What do you guys think about something like that??

[Rabbit on Roids]

Im currently running a T3 on my 1.9 AAZ peaks at about 30-35lbs. But my friend is willing to give me a t3 super 60 he has and Im gonna try and build that for my 1.9. I want to use the cold side from the super 60 and the turbine from the diesel t3.

What do you guys think about something like that??

i think its gonna take DAYS to spool something that big.. considering they run those on pretty big engines. arent they spec'd for something big? like 4 litres and above?

[barrygti]

A Super 60 is a 400bhp turbo on a VR6 etc I think so may be a bit big. And if you go too big and the engine can't consume the air you will probably get surge.

[g-spec]

The t3 super 60 isnt that big....guy run it on turbo 1.8-2.0. It would be way too small to run on a vr6. I think it would be a little big for a diesel but with a proper pump I think it could yield some nice power.