What is max safe boost on old Gturbo (1 Viewer)

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Hi Guys,

I have searched and haven't been able to find solid information on what boost pressures older GTurbo Grunters are designed to run at. Here's my turbo: Do any of you have any information or documentation on what boost pressures this turbo is designed to run?




Thanks for the help,
 

IanB

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Your best bet really is to contact Gturbo directly for an accurate answer on this.
 
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Thanks @IanB That's good advice.

I left a message on the GTurbo facebook page on Friday, messaged Graeme Bentink and used the Gturbo website email option this morning. Hopefully, I will get an official reply from one of those methods. I was hoping that someone on here has experience with a turbo like mine to confirm or deny that my boost levels seem reasonable, in the mean time. (Maybe most guys are running the Badboy or the extreme Grunter.) If I do get a response from somewhere else first, I'll be sure to post it up for future reference!
 

Tapage

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Back in the day Graeme said no more than 24 PSI .. so that's why I run in my G Turbo ..
 
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Here's what Gturbo emailed me last night:

HI Justin,
24psi is fine, we usually have them set to 22psi, but 24 is fine also, they can operate between 14-28psi
The old ones still run as efficiently as the new ones.

Regards,
Sam Hewitt
 

IanB

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Just be aware of the boost dropping off at higher rpms that will bring the compensator pin up and increase your fueling and EGTs.
Can you elaborate on this? I would expect if boost dropped off the pin would follow suit, providing appropriate fueling for the boost level, as the pin is boost referenced rather than RPM. What am I missing?
 
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Can you elaborate on this? I would expect if boost dropped off the pin would follow suit, providing appropriate fueling for the boost level, as the pin is boost referenced rather than RPM. What am I missing?
The compensator pin should ideally be set to give a slightly rich spool (18-19:1 AFR) to increase the drive energy delivered to the turbo. This extra drive energy helps the turbo to spin faster, which in turn builds boost. As the boost level approaches your desired level, the pin either stops moving down due to spacers installed to restrict its depth or the ramp rate on the compensator pin where the pin follower is referencing either decreases or flattens. This is when your fueling level/stroke holds steady while the last few psi of boost is used to increase your AFRs and hence lower your EGTs.
If your selected turbo cannot efficiently deliver your desired boost level higher in the rev range, the delivered air into the engine will either be at a lower boost level than you tuned for, at an increased in temperature or both. It does not matter which path this goes it will result in delivering less dense air to the engine/stroke which will decrease your AFR and increase your EGT.

If you never use this part of the rev range it will never be a problem. If you do happen to use more of the rpm range you should be aware of it.

The fix is to either use a turbo that can efficiently deliver the air you plan to use or to tune to a boost level that your turbo can maintain and allow the waste gate to bleed the excess drive energy into the exhaust.
 
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Wow man. This pin sounds like a PIA. Anyone ever thought about the possibility of removing this thingy......? I much prefer to control fuel the old fation way, with my foot.
 
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Wow man. This pin sounds like a PIA. Anyone ever thought about the possibility of removing this thingy......? I much prefer to control fuel the old fation way, with my foot.
A clever man like you should be able to nut it out gerg

Yeah, wrapping your head around it takes a bit, as does initial set up.
Once it's dialled in, it allows you to fine tune fuel delivery to far greater levels of accuracy than just mashing your foot to the pedal.
Better performance, and response with a far higher safety margin than just having a single fuel screw and your right foot.

I will most definitely fit a BC to my 1Hzzz IP, largely to keep a decent safety margin on EGTs while still being able to optimise performance
 
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I guess yeah. I personally feel it's an emissions control device. I'll have to buy one of these trucks just to see how it works. Anyone every removed it successfully? Been meaning to build a turbo for this engine but it's pretty far down the list.
 
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I think you're probably right that the original intent was to control emissions, it certainly allows a lean idle, even with a rich max fuel setting.
I think to remove it would be throwing away capacity to fine tune and optimise fuel delivery based on boost level.

There has been a handful of mudders fit BC to 1HZ pumps (Karter is one who has done it), so I guess it would be possible to remove one.
 
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Hmm, I wonder if the fuel pump would be twitchy and hard to control? When I put the Mercedes spring into my 3b pump many guys recomended it and said it was a large improvement, but it made my truck extremely hard to drive. 1/4 inch of pedal movment and the pump would go to WOT for a few hundred rpm then mostly cut out. I couldn't wait to put the 35 yr old spring back in. Might just be my experience, but a drivable pump is a lot nicer than a pump that just puts out the most fuel. No doubt the other spring increased fuel, but at a huge expense.
 
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Hmm, I wonder if the fuel pump would be twitchy and hard to control? When I put the Mercedes spring into my 3b pump many guys recomended it and said it was a large improvement, but it made my truck extremely hard to drive. 1/4 inch of pedal movment and the pump would go to WOT for a few hundred rpm then mostly cut out. I couldn't wait to put the 35 yr old spring back in. Might just be my experience, but a drivable pump is a lot nicer than a pump that just puts out the most fuel. No doubt the other spring increased fuel, but at a huge expense.
My two cents is it sounds like the mercedes spring might have been too soft, giving you max fuel at mid boost level and hitting fuel cutoff when you were trying to get to higher boost/RPMs. (Again, I've only been playing with these things for a few weeks so I might be way off)
 
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Could be, although just by feel it felt firmer and it's about 1/4 longer than the stock spring. I might cut one down and see if it gets a performance improvement while retaining drivability. Again, it's down my list of todos though.
 

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