Dawes & Needle question...

[Hodge]

Got a quick question for those who have fine-tuned their dawes and needle valves...
Can altering only the dawes valve, stuff up the whole setup? What I mean is, I turned my dawes valve half a turn back, without touching the needle valve, and it threw the whole thing out of whack. Now it's sluggish, in 4th and 5th like it once used to be. Mudski set this up for me last time but hes away at the moment.

I cannot get it back to where it was, no matter how much I turned it up or down. I wasnt changing the boost much, it was a case of going max 16 to max 14, and then tried going back to 17-18.
I would have though the dawes purely just sets the max boost allowance, and shouldnt affect the spool up rate etc.... But to me it seems like it did.
So in a way, what I'm asking is, do I have to re-set the needle valve, or re-adjust it, everytime I change the dawes valve ?

[Rumcajs]

I would have though the dawes purely just sets the max boost allowance, and shouldnt affect the spool up rate etc.... But to me it seems like it did.
So in a way, what I'm asking is, do I have to re-set the needle valve, or re-adjust it, everytime I change the dawes valve ?

Technically, that is correct, Dawes valve only affect max boost. However if you have set up needle valve fairly conservatively to retard the spool up rate at the expense of max boost that is; it takes longer to reach, by dropping the max boost you have now affected the performance a little.

Better approach would be to set more aggresive spool up and lower the max boost. That will keep the turbo response times better but limit max pressure which more important for the longevity.

So close the needle valve a little to recompensate. These days I only play with Dawes setting as my needle valve is almost shut.

Cheers

[Hodge]

Cheers mate. I'll have a play around tomorrow again.

[Sir Roofy]

What happened to make you fiddle with it ?
I know ,you thought you could get a bit more out
of it fine tune it a bit more lol mate once its set
leave it alone every time you touch it you faark
it up then have to start again and end up where it
was the first time,how do i know this ,i tried every
thing to improve mine a fiddle here a fiddle there
you just cant help it it hooks you your gone and
you keep at it

once set again leave it alone

[Hodge]

I wanted to back it off just a tad. Thinking that it won't throw off the spool up rate, but it did It was maybe half a turn back.
And the car is now doing it's ugly thing when I'm on 4th.
When I drop it into 4th the revs drop below the power band revs which is a 2200 memory and then the car slowly labors it's way it. Before this, it didn't do that. It would easily spool its way back up without hesitation. Weird.

Sent from my SM-G900I using Forum Runner

[BillsGU]

I wanted to back it off just a tad. Thinking that it won't throw off the spool up rate, but it did It was maybe half a turn back.
And the car is now doing it's ugly thing when I'm on 4th.
When I drop it into 4th the revs drop below the power band revs which is a 2200 memory and then the car slowly labors it's way it. Before this, it didn't do that. It would easily spool its way back up without hesitation. Weird.

Sent from my SM-G900I using Forum Runner

When you say "back it off" - which way did you adjust the Dawes valve? Longer or shorter (for want of better terminology)?

[Hodge]

When you say "back it off" - which way did you adjust the Dawes valve? Longer or shorter (for want of better terminology)?

Longer, I unscrewed it to drop off a psi or two.

Sent from my SM-G900I using Forum Runner

[Rumcajs]

Did you mark the position or created reference point before you started fiddling? I always do so I can return back to position it was if I'm unhappy with the results.

Cheers

[Hodge]

Did you mark the position or created reference point before you started fiddling? I always do so I can return back to position it was if I'm unhappy with the results.

Cheers

I did mate. But its not the same. I just went out trying to fine tune it, and getting close but no cigar. Perfect in 1st 2nd and 3rd, all the power in the world. But 4th.... Takes a while to get going...

Sent from my SM-G900I using Forum Runner

[Rumcajs]

Well, something doesn't compute. You have upset something else by fiddling in the engine bay. Now seeing that yours is auto could be this be related to lock up clutch on torque converter? Cause possibly in 4th it is locked and as there is no slip it bogs the engine a little. I'm speculating here as I'm not entirely familiar how CrD operates. Earlier versions would lock up converter above 80 km/h.
In any case I'd close needle valve fully and go fo run. That should give max spool up so only thing affecting boost would be Dawes valve.

Cheers