Stopping the *Surge*

[Bruce]

Working on the general belief that surging with a F/M, and given turbo, was due to the engine's airflow demands not being *in line* with the rate of which the turbo was willing to acclerate, or deccel, I thought I'd try something......
Enter the *Tornado*.
Yes, that little sheet metal, *fan* that fits into the incoming air tract. While I'm leery of some of the claims made for MPG, it did seem like it would help to twist the air into compressor side of the turbo.
I've done allot of tuning to min the surge my car had, but it did still exist. I'm running a stock short block, with a 206/206 cam, 60 PPH injectors, TA-62, Cotton F/M with 3" piping.

I used the model number 75, which seems to indicate an O.D. of 75mm. It took beveling the tubing's ID, and using a hose clamp to compress it enough to fit into a 3" section of tubing immediately prior to the turbo. It needs to be as close as possible to the compressor wheel as possible. Mine slightly hangs out past the tubing, so as to get as close as possible to the compressor....

With so many variables, it's hard to say what you're results may be, but in my case, there's no signs of any surging now....

[Fuelie600]

Sure hope the "Tornado" holds together. Good luck!

[Bruce]

Sure hope the "Tornado" holds together. Good luck!

Time will tell, it looks to be rather robust, ie Stainless, and spotwelded. Being located upstream of an engine, with the potential of breaking apart, and wedging a throttle open, I'd hope they've thought this out... <G>

[Bruce]

Oops I forgot to mention.
No change in AFRs.
No change in EGTs.

Now that I've added a tad more fuel on top, boost is up a couple PSI.

[LiV4gnz]

a blow off valve would noto help tehh surge?

[Bruce]

a blow off valve would noto help tehh surge?

Nope.
Surge is an area just below the sweet spot of the turbo's operating range. Once above or below it, things are fine. A blow off valve is only useful at the high end of the turbos output, or when the boost is still high, with the throttle closed.

[Bruce]

Did a *BUNCH* of datalogs, looking to see what changes there were in the way the turbo spooled up...

The one change from the last logs is the new ignition system, and I still haven't gotten the AE perfect.

As things stand now, the *worst* case, was a 125 RPM *lag* to get into boost, ie 100 K/Pa, and then a 200 RPM increase, to get to 7 PSI.
Looking at several old datalogs, I can find some that show the difference to be min., if at all.

IMO, the differences are within testing variances.
BUT, there is no surging....
Your results may/will vary......

[Bruce]

Well, if one worked well, then 2 should be better, turned out to be a no-go.
No diffference at all.
For it to do any good it must be right up by the compressor wheel.

[TurboBob]

have you tried it any other place than the compressor wheel?

My guess on the reduction in surge is just from the increased restriction.

B

[Bruce]

have you tried it any other place than the compressor wheel?
My guess on the reduction in surge is just from the increased restriction.


Yep, but only in the pre-turbo area.

But, there's no measurable delay in spooling, and the transition into boost, is quicker (in cruise mode).

If it was a restriction, then that should show at WOT, and there's no measurable changes at that level.

[TurboBob]

Yep, but only in the pre-turbo area.
This is where it would reduce surge, did it reduce surge when placed a foot or 2 from the compressor inlet?


But, there's no measurable delay in spooling, and the transition into boost, is quicker (in cruise mode).
I thought you posted a 200 RPM delay.


If it was a restriction, then that should show at WOT, and there's no measurable changes at that level.
At a given boost pressure (regulated by the wastegate), slight pre-turbo restrictions would have negligible effect on power. (in my opinion)