Running 2 Tial 44mm gates, Each with a large red spring (10psi).

On a Dyno Dynamics we were able to make 31psi loading the car up during a 4th gear pull.

We logged all our duty cycle vs. boost pressure readings while on the dyno.

On the street and at the track, our duty cycle vs. boost is way off from what we logged.

Setting our duty cycle to make 31psi of boost, on the street/track car would only make about 22psi.

Im not 100% familiar with how a loaded dyno works, Are you able to create alot more boost on the dyno? We made about 3 times as much boost as our wastegate spring.

Just wondering if a boost leak popped up after we left the dyno, or if its just a matter of re logging boost vs. duty cycle??

Whats the rule of thumb? You can normally double the gate spring? Does this change on a loaded dyno?

Thanks. Don't currently have the car, so cant really do any testing. Just trying to work this out in the off season.

 

I see this alot on our dynapack. Although its not as drastic of a boost loss as what you are describing, but its usually 5-8psi range depending on boost controller/wastegate spring/wastegate size. Our CRX could build tons of boost on the dyno (45psi by accident for example), and at the track with the same boost controller settings couldnt get any more than high 30psi range. We had to make alot of changes in that regard to "track" tune the car.

 

Thats weird, Ive always seen a boost INCREASE on the street over the dyno tuning. I know i was makign 20 psi on the dyno at 99% duty on my boost controller and once i hit the street/track was able to drop the duty cylce down to about 80% for 22 psi

 

Me to but that is on a loadless dynojet. Turbo-LS what dyno are you talking about using?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sp00led &raquo;</TD></TR><TR><TD CLASS="quote">Me to but that is on a loadless dynojet. Turbo-LS what dyno are you talking about using?</TD></TR></TABLE>


Superflow SF-840

On a dynojet i didnt see any differnce in boost from dyno to street in my street car though. on 16 psi

 

I agree, normally you would see an increase on the street, i figured since it was a 4th gear loaded pull, that's why we are seeing less.

I guess what im trying to figure out is, does that "double the spring" theory go out the window on a loaded dyno ?

Its very difficult for me to boost leak test the car, its a top mount manifold, turbo sitting right behind the headlight and everything is vband..lol

Normally i would plug off at the TB and do compressed air into the compressor inlet. Tough to do that in this situation.

Im thinking it is not a boost leak, just wish there was an easy way for me to be sure.

 

John i think even on 22 psi with a boost leak you wwould know. I know on my teg it will still hit 16 psi with a boost leak but definatly not have the guts it normally would without the boost leak on 16 psi because yuor loosing volume. Essentially your loosing the size of the turbo but still makign the boost pressure. Unless you have a stupid boost leak then you wont even make the boost pressure. I been there too. LOL nothign liek blowing off charge pipes mid track

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sp00led &raquo;</TD></TR><TR><TD CLASS="quote">Me to but that is on a loadless dynojet. Turbo-LS what dyno are you talking about using?</TD></TR></TABLE>

If a dynojet didn't put any load on the motor then you might as well dyno the car on a lift with the wheels in the air.

As far as making double your spring pressure, it all comes down to your turbo setup. Eventually, with manifold pressure to the top and bottom of the gate, you're left with exhaust backpressure vs. spring pressure. With a big turbo and low exhaust backpressure you can make a lot of boost on a small spring. I have 10lb springs and can make 47psi on the track, with no co2. If you have a small turbo you're lucky to get much more than double your spring pressure because the exhaust backpressure pushes the gate open.

For the changes in duty on the dyno vs. the track, you will usually see some change, but generally not 10psi difference. Another factor is which boost solenoid you're using and what base spring. The more sensitive the controller is to small changes in duty, the more of a change you're likely to see big changes off the dyno.

 

S300 Control, AEM solenoid, 10lb spring, 4088R.

I have 2 small red springs, i can throw in to make it 15psi if need be.

If i remember correctly i dont think we ever actually put in the duty cycle % for 31psi. I think we tried a few 25-27psi passes and the boost just never got up there.

So i wouldnt go as far as saying its 10+ psi off. But i know it was off by some. If its just a matter of re-logging boost vs. duty, im not sweating that at all.

 

Which turbine housing? I could see not being able to make much over 30psi on those springs with that turbo. When you were settting it up, what duty did it take to make 31psi?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">Which turbine housing? I could see not being able to make much over 30psi on those springs with that turbo. When you were settting it up, what duty did it take to make 31psi?</TD></TR></TABLE>

.95 turbine housing

Id have to check the log at home. But i want to say it was like 92% might have been lower, this was 6 month ago. lol.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo-LS &raquo;</TD></TR><TR><TD CLASS="quote">John i think even on 22 psi with a boost leak you wwould know. I know on my teg it will still hit 16 psi with a boost leak but definatly not have the guts it normally would without the boost leak on 16 psi because yuor loosing volume. Essentially your loosing the size of the turbo but still makign the boost pressure. Unless you have a stupid boost leak then you wont even make the boost pressure. I been there too. LOL nothign liek blowing off charge pipes mid track
</TD></TR></TABLE>

Car went 10.4 on that 22psi pass so it deff had some nut