boost compensators

[juzzy gq racing]

hi guys i think i have a 12 mm pump on my td42 and it doesnt have a boost compensator so i was wondering were can i purchase one and what are the goodies about it and is there any draw backs any info would be a great help

[tye1986]

what makes you think it has a 12mm punger? boost compensators are around $550 should be able to get them from your local deisal inject shop. some people retro fit them off other modelled cars.

[THE-Burger-Ring]

Andrew at diesel tech in Lillydale will tell you everything you need to know.

[juzzy gq racing]

cuz i got it of my mate steve from patrol docta n he saw the receipts yeh i went down to deisel tech in lillydale just got get a compensator n then book it in and get tuned ill buy one of him cherz

[tappo]

i got a old n/a td42 with a denco turbo kit on it, and it seems to be blowing heaps of fuel, wondering if i need a boost compensator, or if i can just back the fuel down a bit???

im new to this diesel stuff... egts.... boost compensators....

egts are a lil high atm, and am told that a big reason could just be to much fuel.... yea? nah?

can i get away with no compensator.... at least till after xmas???

[KiwiBacon]

i got a old n/a td42 with a denco turbo kit on it, and it seems to be blowing heaps of fuel, wondering if i need a boost compensator, or if i can just back the fuel down a bit???

im new to this diesel stuff... egts.... boost compensators....

egts are a lil high atm, and am told that a big reason could just be to much fuel.... yea? nah?

can i get away with no compensator.... at least till after xmas???

A boost compensator is to stop it blowing smoke off boost. It does nothing for fuel consumption.
It sounds like you need a general tune, injection timing and fuel volumes set.

[tweak'e]

i got a old n/a td42 with a denco turbo kit on it, and it seems to be blowing heaps of fuel, wondering if i need a boost compensator, or if i can just back the fuel down a bit???

im new to this diesel stuff... egts.... boost compensators....

egts are a lil high atm, and am told that a big reason could just be to much fuel.... yea? nah?

can i get away with no compensator.... at least till after xmas???

A boost compensator is to stop it blowing smoke off boost. It does nothing for fuel consumption.
It sounds like you need a general tune, injection timing and fuel volumes set.

boost comps make a fairly decent difference to fuel economy. simply because your spending a long time with to much fuel and not enough air to burn it efficiently.

[KiwiBacon]

boost comps make a fairly decent difference to fuel economy. simply because your spending a long time with to much fuel and not enough air to burn it efficiently.

They make no difference to fuel economy. All they do is limit fuel off boost, they're only active for a few seconds of the average journey, whenever your engine is developing enough boost, they're doing nothing.
The boost compensator on my 4wd starts to move at 4psi boost and is fully off by 7psi.

[tweak'e]

i disagree a lot a lot on that. theres been heaps of people with all different engines who have found fitting a boost comp has reduced fuel consumption.
the simply problem is they run to much right foot for the little boost they have a cruise. eg 2-3lb boost but 3/4 throttle. then theres every time your on/off throttle for corners hills etc it chews a bit more fuel as your poking in fuel before the boost is up. it may not be much each time but you change gears a 1000 times, slow down/speed up for corners a 1000 times and it all adds up.

however it would depend on type of turbo setup. with a really small turbo that gets up on boost very quick it would not be such a big problem.

[KiwiBacon]

i disagree a lot a lot on that. theres been heaps of people with all different engines who have found fitting a boost comp has reduced fuel consumption.
the simply problem is they run to much right foot for the little boost they have a cruise. eg 2-3lb boost but 3/4 throttle. then theres every time your on/off throttle for corners hills etc it chews a bit more fuel as your poking in fuel before the boost is up. it may not be much each time but you change gears a 1000 times, slow down/speed up for corners a 1000 times and it all adds up.

however it would depend on type of turbo setup. with a really small turbo that gets up on boost very quick it would not be such a big problem.

The only way you can lose fuel is by having it exit as black smoke. For someone to save fuel with a boost compensator they've got to be blowing an incredible amount of smoke out the back beforehand.
Which implies it's not just the boost compensator that's needed, but a re-tune which they probably got when the boost compensator was fitted to the pump.

[tweak'e]

and they blow smoke like crazy, really easy to see who hasn't got one fitted.
i don't think retuneing (without a boost comp and with the same max fuel) would change anything.
the main thing is using boost comp to limit the fuel in the low boost range.

[KiwiBacon]

and they blow smoke like crazy, really easy to see who hasn't got one fitted.
i don't think retuneing (without a boost comp and with the same max fuel) would change anything.
the main thing is using boost comp to limit the fuel in the low boost range.

Tappo has high EGT's, a re-tune can fix that, a boost compensator won't make any difference. Retuning it to reduce EGT's (fuel volumes and timing) will also reduce off-boost problems. A lot of black smoke doesn't just show too much fuel, it's probably too far advanced as well.

The original poster doesn't know what the problem is, he's just asking if a boost compensator will save fuel. It won't make any difference, especially in Australia where they haven't got hills.

[tweak'e]

he never mentioned exactly what egt's hes getting (high egt is rather subjective) and more importantly under what situation hes getting high EGT's.
no hills
i still maintain that unless hes got a very quick spooling turbo that gets good boost low in the rpm range, a boost comp most certainly will save fuel.

[tappo]

hey guys

you have been quite helpful actually
high egts are "flat to the boards" and got "spike" at 714.... backed off as soon as i saw it go over 700....
crusin round if i dont change down gears just more right foot it can get into the 600s pretty easily...

yea it needs a tune but can quite do that yet.

am just going to back of the fuel screw a wee lil bit and that should get me over the line for xmas and in the new yr will book her in for a solid dyno tune.... and maybe a boost comp.... depends on the cash flow

yea we may not have real mountains but we have a few grassy knolls here n there....

ps cheers for the info greatly appreciated

[tweak'e]

is the egt pre turbo or after? 700 sounds like piston melting !

i certainly would back the fuel screw down. that will fix both problems for the time being but you loose power.
your foot to the boards high temp you could fix by increasing boost and/or intercooler but the 600 at cruise when you give it a bit more right foot is due to no boost comp. your probably blowing a shit load of smoke which is just a waste of fuel.

[brad-chevlux]

hey guys

you have been quite helpful actually
high egts are "flat to the boards" and got "spike" at 714.... backed off as soon as i saw it go over 700....
crusin round if i dont change down gears just more right foot it can get into the 600s pretty easily...

Fahrenheit or Celsius? and pre or post turbo?

[Rhysta]

About to get a 12mm pump built for my patrol, and am tossing up with getting a comp built onto it or not, the car should come onto boost fast, saying that I cant see the comp doing a whole lot.

Is it still worthwhile having it fitted up? I guess the power will come on faster with out a comp as I have the fuel there from the start of the rev range, and wont get a hit of power once the comp turns off.

Can anyone else give any more info regarding them?

Cheers Rhys

[5inchgq]

I just had a pump built by swafftec engineering (swaffie on here) he upgraded a stock GQ pump from a 10mm plunger to an 11mm plunger with a rising rate fuel flow all without a boost compensater.

He spent quite a while playing with governer springs etc.



He bascially guarantees the pump will make 150 to 170hp with the right turbo.

[tappo]

yea those are pre turbo temps.... only ever seen it over 700 once.... most times its below the 600s.... not to keen on pushing the limits....

so more boost? and back fuel off? these combind will make me be able to drive up hills without worrying about egts.....

yes lots of smoke.... equals burning back pocket.... not happy jan!

will give it a crack 2 moz.....

ps how easy is it to increase the boost? and hows it done?? links would be whoot....

ps 5inchgq how much was the upgrade if u dont mind me askin....?

[KiwiBacon]

Your EGT's sound okay, backing down the fuel to reduce smoke will reduce power and can sometimes make a vehicle an arse to drive. It'd be better to find out why it's smoking.
Are your injectors popping at the right pressure? Is the timing too far advanced?
Do you have any restrictions in the intake?
What's the turbo you've got and what's the condition of the blades like? Pull the intake hose and take a look.

Extra boost is done by making the wastegate open later. Either through a device in the line to the actuator or by adjusting the length of the rod. I'm a fan of adjusting rod length (cut and thread).

But at cruise you're normally below peak boost and the wastegate is closed anyway. So getting more boost means finding and fixing turbo problems or fitting a smaller turbine housing.

[5inchgq]

PM sent tappo.

[tappo]

yea its only smokin under full throttle not all the time, so when the fuel is really pumpin in there....
yea might loose a lil power but its better to loose a lil power n be able to drive it rather than nurse it up "knolls" im havin to change dwn to like 3rd sometimes just to get up a mini incline..... pain in the ass....
anyways will have a fiddle n let u know how it pans out...

cheers 5inchgq

[tweak'e]

yea its only smokin under full throttle not all the time, so when the fuel is really pumpin in there....
yea might loose a lil power but its better to loose a lil power n be able to drive it rather than nurse it up "knolls" im havin to change dwn to like 3rd sometimes just to get up a mini incline..... pain in the ass....
anyways will have a fiddle n let u know how it pans out...

cheers 5inchgq

if its smoking under full throttle but not all the time is would suspect when its smoking the boost is low, which is typical of not having a boost comp. either keep your foot off it when boost is low or get a boost comp fitted.
boost comps are commonly fitted over here and i understand its not all that expensive.
not sure why people in AU go to great lengths to avoid fitting one. penny pinching or just knuckle dragging ??

[KiwiBacon]

if its smoking under full throttle but not all the time is would suspect when its smoking the boost is low, which is typical of not having a boost comp. either keep your foot off it when boost is low or get a boost comp fitted.
boost comps are commonly fitted over here and i understand its not all that expensive.
not sure why people in AU go to great lengths to avoid fitting one. penny pinching or just knuckle dragging ??

Many systems don't have a boost compensator for a couple of reasons.
1. The fuel vs rpm curve is set that it doesn't need one.
2. The difference between on boost fuel and off boost isn't enough to create smoke.

So there's a rather narrow spectrum of vehicles that have them. EFI vehicles read air flow and set fuel on that so they don't need them either.

[tweak'e]

if its smoking under full throttle but not all the time is would suspect when its smoking the boost is low, which is typical of not having a boost comp. either keep your foot off it when boost is low or get a boost comp fitted.
boost comps are commonly fitted over here and i understand its not all that expensive.
not sure why people in AU go to great lengths to avoid fitting one. penny pinching or just knuckle dragging ??

Many systems don't have a boost compensator for a couple of reasons.
1. The fuel vs rpm curve is set that it doesn't need one.
2. The difference between on boost fuel and off boost isn't enough to create smoke.

So there's a rather narrow spectrum of vehicles that have them. EFI vehicles read air flow and set fuel on that so they don't need them either.

so they under fuel them robbing you of performance. dunno about you but if i'm going to spend all that $$$ fitting a turbo and getting it tuned i want every bit of performance i can get out of it.

narrow spectrum of vehicles that have them ?? about every light diesel with turbo and mechanical injection that doesn't use a butterfly for fuel control. manufactures fit them for a reason, to stop smoke/emissions when at full throttle and low boost.

well doh! efi uses map/maf and ecu to do the exact same thing a boost comp does. also uses altitude sensor just like mechanical injection systems use a altitude comp.

[KiwiBacon]

so they under fuel them robbing you of performance. dunno about you but if i'm going to spend all that $$$ fitting a turbo and getting it tuned i want every bit of performance i can get out of it.

Most aftermarket turbos on NA engines only run about 10psi boost. That's only 30% more air than non turbo.
With that little change healthy engines won't blow smoke if tuned to sensible egt's.

If you're going for 15+ psi boost then you'll probably need one to stop smoke off-boost. But only a tiny range of aftermarket turbo's fit in this category. Not many NA engines have enough headroom in the fuel pump to do that.

narrow spectrum of vehicles that have them ?? about every light diesel with turbo and mechanical injection that doesn't use a butterfly for fuel control. manufactures fit them for a reason, to stop smoke/emissions when at full throttle and low boost.

Nope, there are many factory turbo diesels which use fuel vs rpm instead of a boost compensator. Butterflys were only used on indirect injection engines from a few manufacturers (like toyota).

[Rhysta]

So to KB and tweake, what do you guys think in terms of loosing much off the line pull with a comp fitted?

Running a gt2876 so I imagine it will spool pretty fast, shutting the comp off early and not doing a whole lot, this is my issue with getting one fitted.

Rhys

[tweak'e]

so they under fuel them robbing you of performance. dunno about you but if i'm going to spend all that $$$ fitting a turbo and getting it tuned i want every bit of performance i can get out of it.

Most aftermarket turbos on NA engines only run about 10psi boost. That's only 30% more air than non turbo.
With that little change healthy engines won't blow smoke if tuned to sensible egt's.

If you're going for 15+ psi boost then you'll probably need one to stop smoke off-boost. But only a tiny range of aftermarket turbo's fit in this category. Not many NA engines have enough headroom in the fuel pump to do that.

narrow spectrum of vehicles that have them ?? about every light diesel with turbo and mechanical injection that doesn't use a butterfly for fuel control. manufactures fit them for a reason, to stop smoke/emissions when at full throttle and low boost.

Nope, there are many factory turbo diesels which use fuel vs rpm instead of a boost compensator. Butterflys were only used on indirect injection engines from a few manufacturers (like toyota).

30% more air.....i would be trying to run 30% more fuel as well. 30% more fuel at no boost is never good. (ok figures stretched a bit but you get the idea).
most of the atmo with turbo upgrades i know blow smoke off boost with mild increase of fuel, let alone someone with modded pump.

would love to know what vehicles don't run boost comps. all the light diesel toyotas, nissans, ford/mazda, mitsi, izusu i know of all do. mind you they all are from '80's to efi era. all run VE style IP's. don't know about industrial or earlier ones.

[tweak'e]

So to KB and tweake, what do you guys think in terms of loosing much off the line pull with a comp fitted?

Running a gt2876 so I imagine it will spool pretty fast, shutting the comp off early and not doing a whole lot, this is my issue with getting one fitted.

Rhys

i doubt it will drop any off the line pull. all depends on how much its over fuelling at the moment. if its been tuned back then it might even improve things as you should be able to shove in more fuel as the boost comes on.

[KiwiBacon]

So to KB and tweake, what do you guys think in terms of loosing much off the line pull with a comp fitted?

Running a gt2876 so I imagine it will spool pretty fast, shutting the comp off early and not doing a whole lot, this is my issue with getting one fitted.

Rhys

Yes you will lose some low end punch. They delay boost arrival as a consequence of smoke control. They are adjustable, so it's finding the balance point to minimise smoke while maximising performance.

Tweake, look for inline pumps with the RSV governor. Isuzu was a big user of these without boost compensators, other manufacturers too.

Regarding 30% more fuel, yes.
The difference between stock AFR ratios of 22:1 (cool, clean and safe) on boost and about 17:1 (above the smoke limit but slightly too hot for sustained operation) without boost.
Which is why below 10psi there's no point in a boost compensator.