1 HDT turbo question

[Vanisljoe]

My wife and I, plus 2 heavy friends just got back from a great camping trip on Cortes Island. Only crappy part- under heavy load the turbo caution light kept coming on, forcing me crawl up each hill and upward grades on the highways.

Beyond me and my wife's weight we had an extra 1000 pounds in the truck and a trailer with load weighing maybe 2000. So call that pulling 3000lbs. Far less than than the 7500 the 1HDT powered '81 is rated to pull.

So what gives?

Any thought?

 

[Hulsty]

Is that the overboost light in the dash cluster? It is just a light that comes on when boost goes past a certain point, I do not know the figures for a 1HDT but, green light from boost to say 12psi then red light from 12psi on indicating higher than normal boost. Is yours stock? Boost guage? Bigger exhaust, more fuel, boost controller could contribute to the boost climbing past stock levels and triggering the light.

 

[Tim-HJ61]

Is that the overboost light in the dash cluster? It is just a light that comes on when boost goes past a certain point, I do not know the figures for a 1HDT but, green light from boost to say 12psi then red light from 12psi on indicating higher than normal boost. Is yours stock? Boost guage? Bigger exhaust, more fuel, boost controller could contribute to the boost climbing past stock levels and triggering the light.

I agree with Hulsty. The 12ht lights trigger at 2psi and 14psi. I imagine the switches are similar for a 1HDt.

Unless you have done any of the things Hulsty suggests, it could indicate a sticking waste gate/actuator. The higher boost isn't so much of an issue, it's not knowing what boost is punching to that is more a concern.

And if you have done any of the things Hulsty lists, and you've not installed a boost gauge, and maybe and EGT gauge, then that's a bit silly....

Tim

Sent from my iPad using IH8MUD

 

[sailor]

hdj81 red light is 15 psi on mine... It is on quite a lot! hehe.

 

[Tapage]

on my 1HD-T overboost light come over 14PSI .. but can be pin hole or just turbo housing to wastegate hose crack ..

 

[Vanisljoe]

I have a pryometer and a boost guage installed. I also have a variable boost adjuster installed with the turbo and the fuel turned up a bit.

Thanks for the info- Guess I can rest easy now!

 

[Tim-HJ61]

I have a pryometer and a boost guage installed. I also have a variable boost adjuster installed with the turbo and the fuel turned up a bit.

Thanks for the info- Guess I can rest easy now!

Okay, that extra info is useful.

The orange light ONLY measures boost pressure.
If you have deliberately increased boost, and have the required gauges, then the light provides no additional information.

Tim

Sent from my iPad using IH8MUD

 

[Adam B]

And when you get sick to death of the stupid lights flickering on and off all the time just remove the boost hose that goes to the boost pressure sensors. The amber one is particularly annoying when your boost is set around 15psi and it's ALWAYS flickering.

I think from the factory the hose T's off from the crossover pipe somewhere, with the other side going to the injection pump boost compensator. If you remove the section going to the pressure sensor then neither the green nor amber light will light up except when you first turn the key on. If you remove the electrical connector from the pressure sensors instead then the lights are always on.

 

[IanB]

And when you get sick to death of the stupid lights flickering on and off all the time just remove the boost hose that goes to the boost pressure sensors. The amber one is particularly annoying when your boost is set around 15psi and it's ALWAYS flickering.

I think from the factory the hose T's off from the crossover pipe somewhere, with the other side going to the injection pump boost compensator. If you remove the section going to the pressure sensor then neither the green nor amber light will light up except when you first turn the key on. If you remove the electrical connector from the pressure sensors instead then the lights are always on.

I guess this same boost hose would be a good spot to hook a boost gauge up to? Or is there a better place to get a good boost reading?

 

[9180ltd]

There is a threaded plug right on the turbo, I just removed it and taped in right there. Works great.

 

[Douglas S]

I guess this same boost hose would be a good spot to hook a boost gauge up to? Or is there a better place to get a good boost reading?

That's what I used.

 

[Adam B]

Either way. I chose to take my boost gauge signal post-intercooler, although now that I think about it if you're really interested in the pressure your turbo is delivering the compressor outlet is better. My boost controller gets its signal there because it's a nice short run to the wastegate actuator.

 

[Tim-HJ61]

Either way. I chose to take my boost gauge signal post-intercooler, although now that I think about it if you're really interested in the pressure your turbo is delivering the compressor outlet is better. My boost controller gets its signal there because it's a nice short run to the wastegate actuator.

I'm not quite sure where you are getting your boost controller signal from? Post intercooler or the compressor outlet.

I assume the 1HDT has a boost compensator on the IP, in the same way the 12HT does.

If so, Graeme and I figured that the IP needs to see the boost ASAP, hence connect the boost compensator at the IP directly to the turbo outlet.
And the waste gate needs to see realtime pressure at the inlet manifold, so take the waste gate line from post intercooler to your boost controller.

I've made up a diagram in PDF to show it for 12HT applications, but the principle still applies to other installations. GTurbo pressure lines

Tim

 

[Enigma]

So what gives?

Any thought?

.......

 

[IanB]

I'm not quite sure where you are getting your boost controller signal from? Post intercooler or the compressor outlet.

I assume the 1HDT has a boost compensator on the IP, in the same way the 12HT does.

If so, Graeme and I figured that the IP needs to see the boost ASAP, hence connect the boost compensator at the IP directly to the turbo outlet.
And the waste gate needs to see realtime pressure at the inlet manifold, so take the waste gate line from post intercooler to your boost controller.

I've made up a diagram in PDF to show it for 12HT applications, but the principle still applies to other installations. GTurbo pressure lines

Tim

That seems like sound logic to me.

 

[Adam B]

Tim, I remember last year when you mentioned that. I considered the idea at the time and didn't bother changing anything. My setup is still the same as stock. The wastegate line comes from the turbo compressor outlet through a boost controller. The boost compensator line and boost gauge line come from post-intercooler.

At some point I may try switching the boost compensator signal over to the compressor outlet side but I'm skeptical as to how evident the difference will be. I already have a little more fuel than I can deal with as the turbo spools up (which is already very fast) so I can't see how I can benefit from having the boost compensator react faster (react meaning add fuel). I guess the idea is to get the boost compensator reacting as quickly as possible and then further increase preload on the compensator spring to get back to the "right" amount of fuel at partial boost. I think the difference will be minimal vs the way it is setup now. That extra boost the compensator is supposed to "see" quickly is a result of something - my right foot - and that is already adding fuel. If I can already dump a little bit of smoke at any boost level if I want to, what's to be gained?

Where you hook up the wastegate line seems irrelevant to me from a strictly performance perspective. I tune my max boost from the gauge. If I switch it around I'm just going to have to adjust the boost controller and end up with the same reading on the gauge. I don't see the real benefit to this either.

One thing that I would expect someone to tell me I'm doing "wrong" is setting max boost from the gauge and taking the gauge reading post-intercooler. I know how much pressure the manifold gets but I don't actually know how much pressure the turbo is putting out. I know which one is higher but I don't actually care how much!

 

[Tapage]

At some point I may try switching the boost compensator signal over to the compressor outlet side but I'm skeptical as to how evident the difference will be.

well I did .. actually I used to have my aneroid conected from the line I was using for my boost controller .. and then for the wastegate .. used that way couple of weeks after G turbo was on ..

Then I swap to more conventional setup, taking signal ( boost ) from my taped IC port for aneroid and leaving wastegate as " factory " conected after my boost controller ..

Not seen any difference ..

 

[Tim-HJ61]

Fair enough guys. Graeme and I muse over things, wonder about problems that 'may' need to be resolved and for this one, we came up with this solution. It might not make any real world differences, but it makes logical sense, and I had fun making up the diagram

What was the problem???
Umm, I think it was trying to overcome any lag caused by the front mount intercooler with long piping and a 600mm intercooler. I've no idea how much air it contains, and in reality, with the fast boost up, lag is imperceptible anyway.

I think measuring boost from the IC outlet/inlet manifold is wise.

They're fun to drive aren't they

Tim