Adjusting a boost compensator

[Rhysta]

Righto, trying to get the turbo to spool lower in the rev range, off boost fuel does not seem to be enough to spool it where I want it.

Its a Gt2876 with a 12mm head once on boost fuel kicks in it takes off and is making good boost, but yeah just want the process to begin earlier.

Have removed the top cover and spun the comp' plunger around so its at its furthest away, have also wound it down as far as it will go and its still not spooling early enough, can basically cruise though 1st and second with out really spooling the turbo.

Is it possible to have a lighter rate spring under the diaphragm? The car blows little smoke until its loaded up over about 8psi give or take, which I assume is when it is kicking on to On boost fuel setting There is also a plastic spacer that I have read of being removed bot didnt want to try it.

Anyways any advice would be tops, will most likely get it dyno'd in the future but Im keen to know how to set it up my self.

rhys

[300WinMag]

Sounds like you may have adjusted your spring the wrong way. Its not as easy to adjust as you might think, you need to put it on a dyno to get the best results as you don't want the fuel coming on to early or to late obviously. Its a matter of tuneing it to suit your turbo. This is why diesel techs charge so much as they have to spend alot of time finding the right components to suit your setup.

But with a bit of trial and error you should be able to work it out.

[Rhysta]

Yeah have spoken with the guy who built the pump, was adjusted the right way.

He doesnt charge an arm and leg like a lot of 4wd workshops as he mainly does earth moving gear etc

But he has a few other tapers for me to try, so its trial and error as you said.

[tye1986]

when does it boost what rpm how many psi, did he do any thing else to the pump?

[Rhysta]

when does it boost what rpm how many psi, did he do any thing else to the pump?

Needs decent load to boost, but probly 1500rpm I would say and will make 25psi if I let it but its not doing it till higher in the rev range, once at speed will make 25psi by 2800rpm. Just trying to get it to spool a bit faster, atm have off boost fuel setting wound up as much as I can, and the spring tension is wound right off, think I may need to look at different taper plunger.

Has had 12mm head, comp, governor linkage modded and i think the cam plate fiddled with but im not sure to what extent.

[UGOTNUFN]

when does it boost what rpm how many psi, did he do any thing else to the pump?

Needs decent load to boost, but probly 1500rpm I would say and will make 25psi if I let it but its not doing it till higher in the rev range, once at speed will make 25psi by 2800rpm. Just trying to get it to spool a bit faster, atm have off boost fuel setting wound up as much as I can, and the spring tension is wound right off, think I may need to look at different taper plunger.

Has had 12mm head, comp, governor linkage modded and i think the cam plate fiddled with but im not sure to what extent.

So have you tried adjusting the max fuel screw at all to increase no boost fuel a little more, and when you say its adjusted as far as you can do you mean that the screw has run out of thread???

IS it smoking at all while trying to make boost below 1500.

[Rhysta]

when does it boost what rpm how many psi, did he do any thing else to the pump?

Needs decent load to boost, but probly 1500rpm I would say and will make 25psi if I let it but its not doing it till higher in the rev range, once at speed will make 25psi by 2800rpm. Just trying to get it to spool a bit faster, atm have off boost fuel setting wound up as much as I can, and the spring tension is wound right off, think I may need to look at different taper plunger.

Has had 12mm head, comp, governor linkage modded and i think the cam plate fiddled with but im not sure to what extent.

So have you tried adjusting the max fuel screw at all to increase no boost fuel a little more, and when you say its adjusted as far as you can do you mean that the screw has run out of thread???

IS it smoking at all while trying to make boost below 1500.

Yeh max fuel has be wound up to create the amount of boost I am chasing, and that did make a difference, but nothing major. The "off boost" screw on top of the comp is wound all the way down, with the tapered profile at its furthest to the rear of the car allowing the slide to come out as far as possible when off boost and the spring tension adjuster inside the comp has been wound all the way down so it takes as little boost as possible to push the plunger down.

This weekend I will have different tapered plungers available to me so thinking that is going to be my next resort.

Unless its loaded right up hard under 1500 then it will smoke until it spools and clears up, under light-medium throttle its not smoking at all.

Thanks heaps for the advice guys much appreciated

Rhys

[tye1986]

i had a 2871 it made 28psi by bout 2200 and surged like crap . if old mate who built it has a deisel bench might be good to chuck it on to see off and on boost fuel rates.

[Rhysta]

Yeah he does, do you guys roughly know what cc's on and off boost your pumps are flowing? Looking for around 140-160 rwkw.

[tye1986]

i have a toyota compensator and can take 70 cc's out can put out 180cc's it was set at 150 cc's max and 80 off boost but i have turned it back a tad as for rest of the pump i dont know they do a lot of fiddling with them. i was making 172kw on 35's at 25psi

[UGOTNUFN]

Sounds to me like you have turbine drive issues,now remember the fuel screw may be able to be turned up some more and has no bearing on how much boost you want to run.

You are trying to drive a 76mm comp wheel which is pretty big to want good boost response down low while driving at low engine load.

The aneroid pin will NOT change how it boosts if you already have the top screw wound down it will already be a fair way down the taper. 80cc no boost fuel should be plenty to spool a properly matched turbo.

If its not smoking down low much off boost i would get on the fuel screw and advise us further.

[Rhysta]

Yeah righto thanks for that, I don't think I can get to much more fuel out of the max fuel screw.

Might look at dropping a compressor housing size, what do you guys think of the 2876? Do you think it's to large to expect what I'm after? Saying I don't think my pump has had as much work done to it as some of your setups have. Possible a drop in compressor size might be an option.

You guys are tops for this info, good to see that not all threads just turn to shite or you get told to search lol

Rhys

[Rhysta]

Out of interest what manifold are you guys running? I have a shite tube style manifold which when it was built got made for a petrol turbo not a diesel and has pretty large tube on it.

A log style manifold would provide faster exhaust gas speeds and therefor spool the turbo faster would it not?

[tye1986]

i have a hight mount denco or dts manifold get em mixed up ,i have just put a turbo on that UGOTNUFN built and suppplied me 30 psi by 2000rpm in 4th gear drops back to by bout 22psi by 4500rpm it is frying my clutch. i never had much luck with the garrett turbo i ran gt2871.

[UGOTNUFN]

i have a hight mount denco or dts manifold get em mixed up ,i have just put a turbo on that UGOTNUFN built and suppplied me 30 psi by 2000rpm in 4th gear drops back to by bout 22psi by 4500rpm it is frying my clutch. i never had much luck with the garrett turbo i ran gt2871.

Great news Tye.

Looks like there is another couple on the way to the East coast this week,not same spec as yours but close.