Outer Limits 4x4 Board

What do people here feel about fuel pump aneroids, a.k.a. boost compensators, on turbo'ed 1HZ motors?

Could the High Altitude Compensator on later 1HZ pumps be modified to function as a boost compensator?

Cheers,
Dave

beanz2 wrote:What do people here feel about fuel pump aneroids, a.k.a. boost compensators, on turbo'ed 1HZ motors?

Could the High Altitude Compensator on later 1HZ pumps be modified to function as a boost compensator?

Cheers,
Dave

expensive! Phill (slowhilux) has had it done to his 1HZ turbo 80. it does save the oil from a bit of soot and gets rid of the nasty takeoff smoke.

I think the HAC could probably be modified successfully into a boost compensator - the mechanism is the same but you'd have to fiddle with the baseline fuelling and probably dick around with the springs to make it add fuel under pressures above 100kPa instead of cutting fuels at pressures below 100kPa. also need to add a spigot to the top cover of the diaphragm housing but that's not real hard.

I wouldn't do it unless it was required for emissions purposes - similar effect can be achieved with careful driving by watching the boost gauge.

Did Phil feel any added power with the compensator?

I wish I have a HAC unit to play with. I've seen the fuel metering rod inside a 1HDT pump but does a 1HZ HAC unit have such metering rod?

Brian, is the 1HZ HAC exposed to manifold pressure at all? Thanks for the reply.

Dave

beanz2 wrote:(a)Did Phil feel any added power with the compensator?

(b)does a 1HZ HAC unit have such metering rod?

(c) is the 1HZ HAC exposed to manifold pressure at all?

Dave

(a)boost compensator will never increase maximum power, it is an emissions device - all it does, like a HAC, is set the max fuel for any given manifold pressure such that the engine is not overfuelled. Without it, you set up the fuelling for a good EGT at full boost, and then in the rare situation where (i) there is zero/less than full boost and (ii) you mash the go pedal, you get smoke.

(b)don't know - have only pulled apart boost compensators. they look the same, the manual for disassembly of the 2L-T pump and the 3L pump with HAC is more or less the same, their operating principle is more or less the same.

(c) no, I don't think so - I am pretty sure there is a vent to atmosphere on the top side of the diaphragm - so unlike a boost compensator it must measure against an internal control pressure or vacuum - instead of atmosphere v boost pressure. I'll go see if I can find a 105 series to "borrow" for an afternoon eh?

dumbdunce wrote: I'll go see if I can find a 105 series to "borrow" for an afternoon eh?

Be sure to send me the fuel pump so I can take it apart

Dave

beanz2 wrote:

dumbdunce wrote: I'll go see if I can find a 105 series to "borrow" for an afternoon eh?

Be sure to send me the fuel pump so I can take it apart

Dave

can you wait a few weeks? have a friend with a 78 series, I can have a look at it to get an idea, but he is away for the next week or so

A boost compesater and hac are different in design. The b/c uses a diaphragm and spring. The hac uses a sealed belows which expands and contracts according to atmospheric pressure. They both are contected to the governor lever in the same way. Trying to adapt one may be almost as costly as buying one outright.

Have fitted 2 b/c to 100 series. It makes the tuning more refined. You may gain a little more power as you dont have to compensate for excessive smoke emmissions with a standard pump.

Hope this helps.

Brian, any pictures would be appreciated. Do only the 100 series and the 78/79 series have HAC on the 1HZ? Later 75 and 80 series don't?

Dzltec, Thanks, that is great information. Looking at a parts diagram, there is what appears to be a metering rod of sorts, shaped differently than the 1HDT metering rod. I was exactly thinking of replacing those parts, LOL. Could you tell me if the boost compensator cap on the 1HDT would fit into the 1HZ fuel pump top?

Dave

beanz2 wrote:Brian, any pictures would be appreciated. Do only the 100 series and the 78/79 series have HAC on the 1HZ? Later 75 and 80 series don't?


Dave

my '97 80 does not have a HAC but I have seen '98 105s with, so in Au at least, I think it's a reasonably safe bet that 75/80 series no, 78/9, 105 series yes. Of course this is toyota and all bets are off.

dumbdunce wrote: my '97 80 does not have a HAC but I have seen '98 105s with, so in Au at least, I think it's a reasonably safe bet that 75/80 series no, 78/9, 105 series yes. Of course this is toyota and all bets are off.

Yup, in other markets the 1HZ has had HAC since the start of the series in 1990.

Dave

beanz2 wrote:

dumbdunce wrote: my '97 80 does not have a HAC but I have seen '98 105s with, so in Au at least, I think it's a reasonably safe bet that 75/80 series no, 78/9, 105 series yes. Of course this is toyota and all bets are off.

Yup, in other markets the 1HZ has had HAC since the start of the series in 1990.

Dave

this is probably because there is no "altitude" anywhere in Australia

What's the highest elevation in the entire continent?

Dave

beanz2 wrote:

What's the highest elevation in the entire continent?

Dave

Charlotte's Pass is a smidge over 1800 meters I think thats the highest road (in NSW anyways), if you could drive to Mt Kozi then 2228 meters.

[/useless fact]

All the top covers on denso pumps will fit each other. There are many variations.

Generally the pumps have to be remove to fit them, as its too hard to get to all the bolts with the manifold fitted..

Cheers

Dzltec wrote:All the top covers on denso pumps will fit each other. There are many variations.

Generally the pumps have to be remove to fit them, as its too hard to get to all the bolts with the manifold fitted..

Cheers

That is good news. I have a pump from a 3L with HAC. I'd like to try to fit the cover with BC to my 1HZ pump if that is the case. Thanks for the info.

Gribble, 2228m is a decently high altitude. How do your vehicles do at that height?

Cheers,
Dave

beanz2 wrote:
Gribble, 2228m is a decently high altitude. How do your vehicles do at that height?

Cheers,
Dave

there's no roads at that altitude - the highest road is, as Sam mentioned, Charlotte Pass at about 1800m, and even that is closed in winter. I've driven it a couple of times in summer and didn't really notice a loss of power or smoke, but that was in the bundera with a boost compensator. There's a dissected plateau we like to call "the Blue Mountains" close to sydney which covers a massive area at 1000 - 1200m that I have driven any number of times in my 80's, with our without boost compensator, there's not a lot of noticable difference. My theory is that the cooler air up there to some extent offsets the negative impact of the lower pressure.