GQ power increase without turbo

Submitted: Friday, Jan 13, 2006 at 23:10
ThreadID: 29677 Views:2892 Replies:10 FollowUps:6
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Hi all,

Another question from my best mate who does not have internet access.

He is a very fussy mechanic and I have tried to talk him into sticking a turbo on his 4.2D GQ Patrol but he is also stubborn and we won't change his mind so let's see if we can help.

He has a pretty heavy offroad camper trailer loaded with all of the goodies and is noticing the drag especially on the highway.
He has been advised to remove his injector pump to have it tuned for bit more power by having an enlarged manifold fitted on the injector pump giving more power. They have also advised for him to fit a full 2.5 inch exhaust system to the standard exhaust manifold saying that extractors on the GQ don't make the difference they do on some other vehicles as they already have a semi-tuned exhaust manifold.

He has asked me to post this on here to see if anyone else has heard of or tried these modifications to the injector pump and exhaust. If so any feedback, positive or negative would be appreciated.

He is planning to have the job done in the next week or so before heading off to Darwin and back fully loaded. The total outlay for this job is about $1200. He has said he does not want to outlay the $4500 to fit a turbo and all of the other things that go with it and just wants a little more snot for overtaking etc.

Thanks for your help,

80 Series T/D
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Reply By: crfan - Saturday, Jan 14, 2006 at 02:24

Saturday, Jan 14, 2006 at 02:24
Hi Big Woody the old turbos on the td42 ws a big no no but they have the set (the good shops) now and are good but xxxe(and worth ity if you can spend the bucks the exhuast is the cheapest. fitting extractors on the d42 dont do a lot .(you will have people tell you do) but they have all ready spent there money .
Toyota owner so take this as you like.
AnswerID: 148470

Follow Up By: Big Woody - Saturday, Jan 14, 2006 at 07:19

Saturday, Jan 14, 2006 at 07:19
Thanks crfan nd that is exactly what we have heard too, that the extractors don't do much on a TD42.

Also Toyota owner
80 Series T/D
FollowupID: 401719

Reply By: Member - David 0- Saturday, Jan 14, 2006 at 07:24

Saturday, Jan 14, 2006 at 07:24
The turbo does make a big difference. I had the pleasure of towing a van with one recently. It had a turbo fitted because the owner towed vans alll the time. The difference was amazing. Best $/KW as well.
AnswerID: 148473

Follow Up By: Big Woody - Saturday, Jan 14, 2006 at 07:27

Saturday, Jan 14, 2006 at 07:27
Hi DavidO,

I know how much difference a turbo makes on a diesel, I have one.
My mate has made up his mind that he does not want a turbo and some of the overheating issues that can go with them so is just after information about injector pump and exhaust modifications for minor increase in power.

FollowupID: 401720

Follow Up By: Member - David 0- Saturday, Jan 14, 2006 at 07:31

Saturday, Jan 14, 2006 at 07:31
Most I have talked to say you won't notice a big difference with better exhaust and extractors- it makes a difference, just not really noticeable.
FollowupID: 401721

Reply By: Member - Brian (Gold Coast) - Saturday, Jan 14, 2006 at 08:39

Saturday, Jan 14, 2006 at 08:39
I had the same dilemna, truck dies when towing the camper trailer, but after talking to a lot of people "in-the-know" about extractors/pumps etc.... decided to go with the turbo. Mine is a 95 GQ, turbo and exhaust came in one kit, did an injector service as well and the difference is amazing! It is well worth the $$$$ in my opinion. Exxy.... yes.... but worth it!
Was fitted last week, injector service during week just gone, pyrometer fitted yesterday, just waiting on a boost guage ......
AnswerID: 148481

Reply By: Willem - Saturday, Jan 14, 2006 at 12:25

Saturday, Jan 14, 2006 at 12:25
My 94 GQ dies on the hills without the trailer.

I have opted to put up with it as long as everyone behind me is patient as well LOL

The more you stuff around with these older trucks the more trouble lies in store for you...Damn Murphy!!!!

Ways to improve speed is to take the roof rack off and go back to smaller skinny tyres. Alos look for mainly down-hills...hahhahaha
AnswerID: 148516

Reply By: cokeaddict - Saturday, Jan 14, 2006 at 12:25

Saturday, Jan 14, 2006 at 12:25
Hi Brett,
A mechanic would be the first to know that IF it was possible to do what he wants, no one would bother with turbo's. What he wants to do will make no difference at all. Not for the $1200 bucks he will waiste doing it.

think about it mate, if Nissan knew of a quick fix to power up GQ's, dont you think it would have been done from new?

I had a GQ 1988 4.2 Diesel (non turbo) 600,000 kms on cock and still hammering strong. But put a trailer on the back or load it up and forget it. Get stuck behind a semi trailer and thats where you will sit.

He wont come anywhere close to having the "overtaking power" he spoke of by spending his 1200 bucks.

I cant imagine going back to a std 4.2 diesel GQ with a trailer on back ever again. They are snails, but in saying that, they will get you back home every time.

Just cant be done unfortunately.

AnswerID: 148517

Follow Up By: Gajm (VIC) - Saturday, Jan 14, 2006 at 21:34

Saturday, Jan 14, 2006 at 21:34
600,000 kms on what??
FollowupID: 401817

Follow Up By: Member - Roachie (SA) - Saturday, Jan 14, 2006 at 21:58

Saturday, Jan 14, 2006 at 21:58
That's bloody long way to go on a cock....OUCH!!!!!!

Seriously, Ange is right (again as usual). Your friend is either gunna have to bite the bullet and put the hair-dryer onto the GQ, or put-up with the lack-lustre performance he is currently experiencing.

The over-rider is that he should have his injectors done (exchanged or re-calibrated etc), timing etc. BUT.....none of these things is gunna come even close to the turbo option. Tell him to keep his $1200- and buy some valium tablets to keep his blood pressure down if the sluggish truck is making him a bit hot under the collar.

If he CAN afford the turbo, but doesn't think it's worth spending the dough cos the GQ has got a few klicks up, tell him that a GQ is good up to 500,000klm before having a turbo fitted (rule of thumb of course) and he will recoup a good portion of his outlay when he finally sells the old GQ......But, I reckon once he's got a turbo on it, he won't ever want to part with it!!!!


FollowupID: 401819

Follow Up By: cokeaddict - Sunday, Jan 15, 2006 at 12:57

Sunday, Jan 15, 2006 at 12:57
did i say cock..!!!!...i dont remember 600,000 kms of that happening.

sorry guys ..typo.
FollowupID: 401898

Reply By: Truckster (Vic) - Saturday, Jan 14, 2006 at 18:13

Saturday, Jan 14, 2006 at 18:13
$4500 on a turbo? Gee they must have gone up in price in recent years.

Don't waste your money on extractors and 2.5in exhaust. Not worth it.

The pump rebuild will usually do something, but not enough to make it worth while, and he will be disappointed with the described mods of pump and zaust..
AnswerID: 148554

Reply By: Member - JohnR (Vic)&Moses - Saturday, Jan 14, 2006 at 21:23

Saturday, Jan 14, 2006 at 21:23
Was talking to a Sandgroper in the Biloela cvp from that had a GQ and had the pump advanced a bit. Reckoned it had given him quite a boost in the capability pulling the caravan.

Have a look at Outerlimits page here for some discussion by a guy who has done it
AnswerID: 148592

Reply By: Flash - Sunday, Jan 15, 2006 at 01:18

Sunday, Jan 15, 2006 at 01:18
Yeh, I discovered I made a big mistake when I fitted a turbo on my GQ a few years ago.....


Absolutely transformed the Patrol- better everything including fuel economy. And yes it did cost about $4500 including big exhaust and power-up mod, but worth every cent. Goes like a big V8, no problems and no overheating etc (Fixed the viscous fan and cleaned the radiator plus a high flow thermostat when I did the turbo) (It's a modded DTS turbo running 12psi boost)
I love driving it a lot more now, bye bye slug.
I would suggest he hangs on to his $1200 til he can do a proper job.
AnswerID: 148658

Reply By: Ascot - Sunday, Jan 15, 2006 at 08:06

Sunday, Jan 15, 2006 at 08:06
Goodday fellas,
A few simple things can make a difference, first throw away the paper air filter or if its a finer filter do the same, put in a K&N, you will notice a big difference with the motor being able to breath better and rev more freely.
I think I know where your mate is coming from, he doesn't mind how long it takes to get there but likes to see a clear road ahead.
Happy motoring.
AnswerID: 148677

Reply By: DesC - Monday, Jan 16, 2006 at 18:59

Monday, Jan 16, 2006 at 18:59
I put extractors only (no exhaust system) on my 92 GQ at 250 000km only because it popped a few exhaust manifold studs, and extractors back then were only $240 for the Genie variety. (it was going to cost me $100 to machine the old manifold). I can tell you that i was never totally happy with the fuel economy before at 13.2 - 14 lp100km (at 100 kmh not towing and no roof rack or big wheels). But after i fitted them on a normal run i achieved 10.9 lp100km.i also noticed a reasonable increase in midrange torque. I now have a GU TD42 that achieves about 13.5 lp100km and I think i may take the plunge on a set of extractors again. Because at $420 if i increase my economy by 2 litres per 100km at $1.25 a litre of diesel they will pay for themselves in around 17000 km of driving and then after that it will be a bonus. As for getting your money back on a vehicle fitting a $5000 turbo intercooler kit i think i would prefer to put that $5000 towards the lease payment on a new GU4.2 that is turbocharged and intercooled from the factory with 5 years warranty.
PS i think just getting rid of that flexible joint in the old engine pipe would have helped a fair bit.
AnswerID: 148980

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