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Question Is a 1 bar boost spring asking for trouble?

I noticed in my receipts that there is a 1 bar spring in my tial wastegate. My CIS is totally stock and the car seems to run great overall. I usually only jump into the turbo power for short bursts, either 1st or 2nd gear ....maybe for 5 seconds at a time total in 2nd. I am really not wanting to melt any pistons.

The factory boost gauge reads a solid 1 bar at max boost. I haven't ever noticed any detonation. What do you guys think?
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.

Last edited by Maxx1; 09-16-2007 at 11:58 AM..
Old 09-16-2007, 11:49 AM
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what I think is that you saved about $500.00 by not having to buy a tial waste gate with a 1 bar spring.
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Old 09-16-2007, 01:00 PM
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Yes. I believe it is. You can always raise boost from stock 0.7 bar setting by introducing leak orifice between wastegate and plenum (there are many ways of doing this, from 5$ plastic T-nipple to programmable EBC). You can also lower it back to 0.7 bar when needed (hot weather, only low octane gas available). When using 1 bar spring, you are locked to 1 bar whatever happends.

I would at least do a LM1 run to check AFR's and check and recheck timing.
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Old 09-16-2007, 01:04 PM
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You are fine. As long as it's street driven only and short bursts. Do you have a larger intercooler? If not, I would recommend that. Otherwise, I wouldn't worry about it. If you are that worried about it you could go back to the stock .8 spring.

Right now, I run a 1bar spring, B&B intercooler and a GHL muffler on the street only. Not one issue thus far.

The LM1 or a Gunson is never a bad idea to set the AFRs. I use a Gunson and set my CO and rechecked it as the weather cooled down.
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Old 09-16-2007, 02:12 PM
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Quote:
Originally Posted by wcc View Post
You are fine. As long as it's street driven only and short bursts. Do you have a larger intercooler? If not, I would recommend that. Otherwise, I wouldn't worry about it. If you are that worried about it you could go back to the stock .8 spring.

Right now, I run a 1bar spring, B&B intercooler and a GHL muffler on the street only. Not one issue thus far.

The LM1 or a Gunson is never a bad idea to set the AFRs. I use a Gunson and set my CO and rechecked it as the weather cooled down.


No, my intercooler is stock. I too have a GHL muffer and B&B headers. I would think a .8 replacement spring would be a cheap fix? ...wouldn't it
?
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 09-16-2007, 04:32 PM
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With your setup I would definitely change to the .8 spring. If for no other reason but boost creep. Others on this board have (or had) your setup and get more boost then their springs are set for. So yes change to the .8 spring and keep an eye on the amount of boost you're actually getting.

.8 for sure. But you should consider a larger intercooler too. No affil, but I'm really happy with the B&B from IA that I just got.
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Old 09-16-2007, 05:21 PM
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Changing the spring is very easy. When I bought my turbo I had two springs, .8 and .3. I removed the .3 just to be safe. The car WAS insanely fast both with those springs in it. I used to have a chart that said the boost level based on the color of the paint on the spring...

Bill
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Old 09-16-2007, 06:21 PM
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Originally Posted by BSiple View Post
Changing the spring is very easy. When I bought my turbo I had two springs, .8 and .3. I removed the .3 just to be safe. The car WAS insanely fast both with those springs in it. I used to have a chart that said the boost level based on the color of the paint on the spring...

Bill
Thanks, I'll contact Tial and see what they have.
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 09-17-2007, 09:11 AM
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No problem Maxx. Do a search on here and there are a couple of threads on safely changing the springs. If you have a large enough vise or some clamps, you will want to use either one, and the spring is under tension, and when you take the last bolt out, you don't want the top of the WG turning into a projectile...

Bill
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Old 09-17-2007, 09:18 AM
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I have a Tial 46mm on mine with a .80 bar spring in it. I have found that with some after market headers (B&B and OBX are the two that have been on my car), that their flow characteristics will often cause more boost. I know there is a term for this, but it escapes me. So by running a .80 bar spring, I actually see pressures of .90 bar at my aftermarket guage. Just food for thought...
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Old 09-17-2007, 12:37 PM
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Quote:
Originally Posted by sand_man View Post
I have a Tial 46mm on mine with a .80 bar spring in it. I have found that with some after market headers (B&B and OBX are the two that have been on my car), that their flow characteristics will often cause more boost.
It's called boost creep.
However, the .1 bar difference your seeing could easily be within the accuracy and resolution of your boost gage.
Real boost creep would be like if you were getting 1.2 bar with an .8 bar spring.
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Old 09-17-2007, 02:26 PM
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Quote:
Originally Posted by BSiple View Post
No problem Maxx. Do a search on here and there are a couple of threads on safely changing the springs. If you have a large enough vise or some clamps, you will want to use either one, and the spring is under tension, and when you take the last bolt out, you don't want the top of the WG turning into a projectile...

Bill
Thanks for the tip. Spring loaded surprises are always fun.
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82 Porsche 930 Euro, black, 31K miles.
Factory stock other than k27 turbo, B&B headers, GHL exhaust, Tial F40, 1 bar wastegate, MSD 6A ignition, 8" and 9" Fuch upgrade, H4 Xenon headlamps and a 930S steering wheel.
Old 09-19-2007, 04:36 AM
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What causes the boost creep?
Please explain the actual physics behind it, because it does not sound like a symptom of which wastegate you own but rather the exhaust header design.
Old 09-19-2007, 11:56 AM
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I run 1.2 on the street and .8 on the track. you should be fine.
Old 09-19-2007, 01:20 PM
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Quote:
Originally Posted by fredmeister View Post
What causes the boost creep?
Please explain the actual physics behind it, because it does not sound like a symptom of which wastegate you own but rather the exhaust header design.
There are many names for different things that can happend.

Wastegate creep: when wastegate spring is too soft and is cracked open by exhaust backpressure before wanted boost is obtained. Usually leads to more time before full bost is online. Cured by fitting harder spring or using EBC with pressure delivered on both sides of membrane.

Boost creep: condition when boost "creeps" upwards from desired value. Often provoked by too small wastegate and big turbo. Example: engine that spins at 3000 RPM, boosting 1 bar will need certain amount of gases evacuated trough wastegate to keep that boost steady. Wastegate will have sufficient diameter to obtain flow and everything is OK. When revs rise, amount of exhaust gases needed to flow trough wastegate also rises, increasing the backpressure trough wastegate. Instead of being dumped aboard, gases are forced to pass trough turbocharger instead and boost starts "creeping" upwards at higher revs. Cured by fitting bigger wategate.

And then there is typical syndrom of "my 0.7 bar wastegate now delivers 0.9 bar of boost after I fitted free flowing exhaust/bigger turbo. The reason for this is abvious: if you decrease exhaust backpressure for turbo/exhaust combo, gases will more likely flow trough turbo than trough wastegate. Result is same as fitting harder spring: higher boost troughout the range, but without "creep". Cured by fitting softer spring.
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Old 09-19-2007, 01:39 PM
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