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Maximum Horsepower From GU Injector Pump

22622 Views 45 Replies 24 Participants Last post by  GQ Nissan Mad
I recently put the TD42 on the dyno and got a healthy 110rwkws with a very smooth power curve. So this got me thinking on how i could get the 130rwkws that the GU Pump is allegedly good for.
The Turbo setup is good for this power, it is just lacking the fuel.
The problem I'm having is i cant screw the Max Fuel Screw in any more without the revs hanging, no matter what setting i have the aneroid in.
Do modifications actually need to be made to the boost compensator, injectors and pump or is it just a matter of altering settings?
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mmmm, I'll keep my eye on this thread. What EGT'S are you running??maybe PM dieseltech for an opion(andy)
not sure if they are capable of that in stock condition.
If they have the high rpm linkage inside removed you will notice a large increase in top end power and therefore get your HP figures on the dyno.
ATM the standard pump config backs the fuel off at high rpm for emissions control.
Talk to your local fuel pump center, they should know about it and should be able to do it for about $850 to $900.
If they don't know what your are talking about, they should not be working on fuel pumps, as this is one of the most common nissan fuel pump mods.
I reckon I've read of a mod where the existing 10mm plunger is replaced by a 12mm version. I'm not sure of the cost or the availabillity, but if you do a search for posts by OldMav about power, or pumps - you might find what you need.
I reckon I've read of a mod where the existing 10mm plunger is replaced by a 12mm version. I'm not sure of the cost or the availabillity, but if you do a search for posts by OldMav about power, or pumps - you might find what you need.
certainly is,
That is one of the mod's I have done to mine.
made a massive difference
availabiltiy is no probs and the head alone is about $400-$500 plus fitting.
I was just trying to get the most from the stock IP.
EGT's are low like 350C max
I would really like to hear from the guys making 130rwkws and what has been done to their IP to reach this.

I might have another play tomorrow. I think i might have set the spring preload on the diaphragm to soft so when it started to make boost it added more fuel causing the revs to hang. Although this doesn't solve like when changing between gears..
Yes it is possible, mods do get done to the boost compensator on the vehicle. Tyres play a big part in ultimate power. The pump has to have a 11mm head and rotor as standard. Upgrading to 12 can be done if you want more power.

You must know how a boost compensator works and how fuel is adjusted to get the most out of it.


Andy
To give you an idea of what Andy is talkin about on tyre size making a difference. PS. this is stock pump that is leaking now :(
ANDY.. HELP!!!! hmmmm.. 12mm plunger time :D

265's V 285's

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That graph is interesting as its essentially what I'm getting. Your GU, Truckster, I'm assuming? Was that the limit of the Injector Pump?

My injector pump is indeed the 11mm and i have verified with the serial number pressed on the side.

Andy when you say the Compensator is modified in what way? Can the compensator be used to regulate fuel at zero thottle? It appears that the boost compensator doesnt come into play until approx 3/4 throttle movement.

To increase fuel coming out of my pump, short of 12mm plunger, i need to limit the fuel at zero throttle.

I'm starting to think ive reached the limitations of the stock injector pump
That graph is interesting as its essentially what I'm getting. Your GU, Truckster, I'm assuming? Was that the limit of the Injector Pump?

My injector pump is indeed the 11mm and i have verified with the serial number pressed on the side.

Andy when you say the Compensator is modified in what way? Can the compensator be used to regulate full at zero thottle? It appears that the boost compensator doesnt come into play until approx 3/4 throttle movement.

To increase fuel coming out of my pump, short of 12mm plunger, i need to limit the fuel at zero throttle.

I'm starting to think ive reached the limitations of the stock injector pump
Think you better send your car or pump to Andy and let him set it up for you. The compensator has lots of functions and it all ties in with max fuel/boost pressure/turbo spool rate etc.

MAtt
I'd have to disagree with you matt to my understanding the compensator is a rather simple piece of gear. Just a progressive valve controlled by pressure, be that from forced induction or atmospheric. You have control on when it starts to operate and its initial position which in turn affects the amount of fuel injected thereby altering things such as Turbo spool rates.
I'd have to disagree with you matt to my understanding the compensator is a rather simple piece of gear. Just a progressive valve controlled by pressure, be that from forced induction or atmospheric. You have control on when it starts to operate and its initial position which in turn affects the amount of fuel injected thereby altering things such as Turbo spool rates.
And that isn't what i said in my post???????

Oh well carry on you must know what youre doing.

MAtt
You are 1/2 way there to understanding how it works. Once you know fully, you will then know what to modify. You also may have found the limit of your pump, its then time to make a decision. We haven't seen any GU 11mm pump go above 130rwkw with any mods we have done.


Andy
Sorry Matt i value that you did make a contribution to the thread. It just frustrates me when people say just take it to a specialist when i can give it a go myself, with a little guidance. So i guess i was just showing you that i do have a fair idea on whats going on. There's specialists out there half the time because people dont take the time to understand how things work. Not to take anything away from what these diesel guys out there do, especially when they're doing modifications like 12mm plungers they really come into their own.
114rwkw on 33' muddys with a IP that has been completely setup by myself i think that's not to bad. I was just trying to see if i could extract some more hp for jam.

Well that's my little rant i guess. I suppose ill just have to accept that without some serious pump mods the big rig isn't going to be a Formula 1 racer.
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Sorry Matt i value that you did make a contribution to the thread. It just frustrates me when people say just take it to a specialist when i can give it a go myself, with a little guidance. So i guess i was just showing you that i do have a fair idea on whats going on. There's specialists out there half the time because people dont take the time to understand how things work. Not to take anything away from what these diesel guys out there do, especially when they're doing modifications like 12mm plungers they really come into their own.
114rwkw on 33' muddys with a IP that has been completely setup by myself i think that's not to bad. I was just trying to see if i could extract some more hp for jam.

Well that's my little rant i guess. I suppose ill just have to accept that without some serious pump mods the big rig isn't going to be a Formula 1 racer.
I totally understand mate,and i appluad you for having a go.But if we gave every tom dick and harry all the information and secrets to make power ,then there is no point being in business. I made the same mistake years back and was told in no uncertain terms to go and find out yourself, so i did and now i have a very good knowledge and understanding and can put together some serious power packages.

Having said that, i would say that if you were prepared to send your vehicle or pump to Andy at Diesel-Tec he could probably get that little bit extra that you are looking for.

MAtt
This is the only hobby/tech scene that I have ever been involved with that information is so secretive. Yes, people have business interests linked to specific setups but then again what proportion of people that are actually looking to modify at home were going to take it to a diesel technician anyway? Seems like the only reason that it is this way is cause not many people play with Nissan diesels compared to their petrol brothers so the number of people willing to share information is just not there. Is it not a partol4x4 forums rule that promotion of business is not allowed in this section, why are any businesses even being plugged here? All I see is an ad for Diesel-Tech so far with vague assertions that they know what they are on about. If you have a recipe share it, if enough like minded people also try it and give input/feedback, the results will improve..oh wait..that's other forums...
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This is the only hobby/tech scene that I have ever been involved with that information is so secretive. Yes, people have business interests linked to specific setups but then again what proportion of people that are actually looking to modify at home were going to take it to a diesel technician anyway? Seems like the only reason that it is this way is cause not many people play with Nissan diesels compared to their petrol brothers so the number of people willing to share information is just not there. Is it not a partol4x4 forums rule that promotion of business is not allowed in this section, why are any businesses even being plugged here? All I see is an ad for Diesel-Tech so far with vague assertions that they know what they are on about. If you have a recipe share it, if enough like minded people also try it and give input/feedback, the results will improve..oh wait..that's other forums...

Plenty of information to be shared Australia wide,not promoting business just giving someone that is possibly geographically closer than me to the thread starter a heads up on who would be the best person in my opinion to go and see about what he wants to do.

MAtt
As for Andy, do you know what a disco potato is?? .
I think so, he has about 4 of them on the shelf in the office... :lol: :lol: :lol: :lol: :lol: :lol:
The magical "turbo". Made by Garrett.


More cloak and dagger stuff around this than a decent novel.
I am with IS400X,

And I will add Madrolla if you can’t answer the question then don't. You obviously can't so don't fluff it.

As for Andy, do you know what a disco potato is?? I spoke with you personally on the phone and I asked if you use disco potato and you questioned me what is that, disco potato???

No disrespect meant here (I think) but answer with fact and not PULP FICTION.

Cheers.

got to love forums......if people ask questions it is up to the individuals responding to share as much info as they want.....If everyone did stuff at home and there was no dsl professionals then what would happen....another industry lost....
I agree it is good to give things a go yourself but some things are better left to those in the know....I have bought a gu 4.2 recently and prior to that had a gq with a 4.2td in it which had custom intercooler pump etc.....I went to a dsl specialist to get it tuned and that made all the differance..i will be taking the new truck to the same place without hesitation....remember i think everyone on here has one goal and that is tough patrols....whether it be daily driver,tourer or race truck...

good luck with what ever you do decide to do harty.....
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