How Do I Increase My Fuel Economy/Performance??

[Kwakka73]

I have a 1991 GQ 4.2 Carby and I am investigating options around increased fuel economy (and potentially performance. Don't want to do a Gas Conversion as I don't do big K's in it but still want o maximise economy/performance if possible. It is stock as rock (engine) so just want to find out if I should go Full Exhaust System, Snorkel etc and anything to Carby (if possible??).

Any Advice Appreciated

Cheers

[Ben-e-boy]

its the same with every motor mate, More Air in (snorkle and quality air filter), more fuel to match, better spark, better exhaust. and a tune. A change in driving style will help too, install a vacuum gauge and it will tell you when you are driving at peak efficiency

Benny

[Kwakka73]

Cheers Mate

[dirtaddict]

pretty hard to get better than 18 per 100 k`s from those engines , i`de turbo charge it if your serious about it , got a mate with a turbo`d one , goes like stink and better economy when driven sensibly , that is shifts under 2500 rpm , he revs it 3500 though so it chews juice (and tyers )

[Robo]

As above.
If turbo and shifting at 2500rpm is the go then I'm sold.
BUT your needs first.

Pertronic ignition conversion.
Extractors. (insulated)
2-1/2 exhaust.
snorkel..
reco carby.
for a start at least.
will see fuel and torque improvements.

[Silver]

G'day Robo, the extractors on my TB42 are not insulated. What are the benefits of insulating them?

Rick

[macca86]

G'day Robo, the extractors on my TB42 are not insulated. What are the benefits of insulating them?

Rick

Keeping heat out of the engine bay. cool air = dense more oxygen hot air= thin less oxygen to burn

[Bigrig]

pretty hard to get better than 18 per 100 k`s from those engines , i`de turbo charge it if your serious about it , got a mate with a turbo`d one , goes like stink and better economy when driven sensibly , that is shifts under 2500 rpm , he revs it 3500 though so it chews juice (and tyers )

Agreed - I've turbo'd mine, getting well under 18lph (just under 16) on the open road and have the auto (via TPS) changing up at low revs for economy when driving normally (in overdrive by around 50klms per hour in fact).

[MQ MAD]

I have a 1991 GQ 4.2 Carby and I am investigating options around increased fuel economy (and potentially performance. Don't want to do a Gas Conversion as I don't do big K's in it but still want o maximise economy/performance if possible. It is stock as rock (engine) so just want to find out if I should go Full Exhaust System, Snorkel etc and anything to Carby (if possible??).

Any Advice Appreciated

Cheers

Before you go shelling out good money on performance parts or chasing that elusive cheap running TB42
Go get a full checkout of the motor
It could being the age most are now and the Ks they have, be well worn now and maybe mite need a rebuild
This age thing and high Ks will help gobble that fuel
The TB42 carbs were never ever cheap to run when new,way back when
They use as much fuel as an early GT 351 falcon,thats terrible,i reckon you could get the GT to run cheaper than the TB42 ...
Then after a full engine condition report id get the carb checked out for maybe air leaks, dud seals or leaks here and there
Extractors and all the other stuff will help on a tired ol engine but they will help better on a healthier engine

[Kwakka73]

Thanks to all - much appreciated

[dan&tamspatrol]

mate i know you said you didnt want gas coz you want to maximise economy/performance but if you go injection you wont lose any power from petrol and running gas is very much the same i have it on mine and havent noticed any drop in performance just thought id throw it out there as food for thought

[dan&tamspatrol]

the system i have runs 2 computers 1 for gas and 1 for petrol hence no loss of power

[Robo]

G'day Robo, the extractors on my TB42 are not insulated. What are the benefits of insulating them?

Rick
Improved gas velocity, and lots and lots less noise.
Stable exhaust temp gasses maintain velocity better hot, than cooling down and becoming dense.
OR, sorta creates its own back pressure as it cools, reducing performance.
Good reduction also in under bonnet temps.
Less burnt arms and hands.
I took mine off and wrappped em ebay cloth.
Not a nice job to take on with extractors installed, swear words deleted here.trust me.
Very happy with the good amount noise reduction.
Dunk cloth in a bucket of water it's easier to handle wet. and less splinters and fibre dust particals to breath.
An old pair of scissors to cut it to length works fine.
Stainless fishing leader wire is a good tidy way to wrap and clamp in place.
Lots of steam and smell when you fire back to life but soon gone, don't do this indoors.
Cheers

[97_gq_lwb]

the system i have runs 2 computers 1 for gas and 1 for petrol hence no loss of power
You most likely have power loss on petrol due to the size of the mixer ring used in a typical conversion checkout the inside diameter it will be about half the size of your throttle body wich equates to half throttle lol
If you have this type try removing it and taking it for a drive on petrol and see what happens.

[dan&tamspatrol]

i dont have mixer system i have the injection system it get puts straight into the cylinders

[97_gq_lwb]

Laughing the best system.

[dan&tamspatrol]

yep cost a pretty penny to

[Robo]

More air at the ready does not really mean more fuel.
unless you use it, ie - right peddle.
Fitting a snorkel for instance will free up a intake system.
The more a engine has to work on drawing it's next breath, the more fuel is spent.
this equates to using more right foot.
Cold air forced induction is a must have for economy and performance gain, end of debate.
Its how you use it, that's the economy factor debate.
cheers

[dom14]

Improved gas velocity, and lots and lots less noise.
Stable exhaust temp gasses maintain velocity better hot, than cooling down and becoming dense.
OR, sorta creates its own back pressure as it cools, reducing performance.
Good reduction also in under bonnet temps.
Less burnt arms and hands.
I took mine off and wrappped em ebay cloth.
Not a nice job to take on with extractors installed, swear words deleted here.trust me.
Very happy with the good amount noise reduction.
Dunk cloth in a bucket of water it's easier to handle wet. and less splinters and fibre dust particals to breath.
An old pair of scissors to cut it to length works fine.
Stainless fishing leader wire is a good tidy way to wrap and clamp in place.
Lots of steam and smell when you fire back to life but soon gone, don't do this indoors.
Cheers

Hi mate,
What is the sealant between the gasket and the extractors in the second photo?

[Cuppa]

http://www.nissanpatrol.com.au/forums/attachment.php?attachmentid=59139&stc=1

[threedogs]

Good thread dig but
Dom I think its a RTV exhaust type sealant very good for its chosen job

[dom14]

Good thread dig but
Dom I think its a RTV exhaust type sealant very good for its chosen job

Ok, cool. I didn't know we can use silicon type sealant on exhaust. I thought it would simply burn and cook itself in no time.
The orange colour of the sealant is probably not the original colour??!! May be it turned orange from heat?!

The reason is that I'm interested in a sealant that can hold the seal of exhaust pipe flange to flange or manifold to head(at least for few days), in
a situations the gasket fails due to a leak or wear/tear.
Thanx mate.

P.S. My apologies for :hijacked: :D

[pat in a troll]

"muffler cement" in it's various forms can patch exhaust leaks, but isn't really a long-term solution. it'd definitely stop exhaust gases from exiting where they shouldn't but if an exhaust is already leaking at a flange gasket, the flange gasket would cost as much as a repair product. here are some forms of it (that supercheap carry)
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Bandage-5-x-106cm.aspx?pid=5363#Description
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Putty-113g.aspx?pid=5368#Recommendations
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Sealer-80mL.aspx?pid=129932#Description
http://www.supercheapauto.com.au/online-store/products/CRC-Maniseal-Exhaust-Cement-Brown-145g.aspx?pid=1449#Recommendations

[dom14]

"muffler cement" in it's various forms can patch exhaust leaks, but isn't really a long-term solution. it'd definitely stop exhaust gases from exiting where they shouldn't but if an exhaust is already leaking at a flange gasket, the flange gasket would cost as much as a repair product. here are some forms of it (that supercheap carry)
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Bandage-5-x-106cm.aspx?pid=5363#Description
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Putty-113g.aspx?pid=5368#Recommendations
http://www.supercheapauto.com.au/online-store/products/Permatex-Muffler-Tailpipe-Sealer-80mL.aspx?pid=129932#Description
http://www.supercheapauto.com.au/online-store/products/CRC-Maniseal-Exhaust-Cement-Brown-145g.aspx?pid=1449#Recommendations

Hi mate,
I've tried all of them in the past except number 3. I still got Maniseal and Permatex putty.
What I was referring to was something you apply on the flange gasket.
Lets say the flange surface is either pitted or warped and regardless of putting a new flange gasket
it would leak and cause more damage to the gasket and the flange.
I was wondering whether there's a semi-permanent(or permanent) sealant that I can paste on the flange gasket and flange face
before I fit the gasket.

[Robo]

Hi mate,
What is the sealant between the gasket and the extractors in the second photo?

Hi temp exhaust silicon.
the extractors leaked a bit previously.
Also very carefully surface ground and straight edged the extractors flange to help flatten them, to seal old leak and it worked well.

[threedogs]

Old school was to wipe the gasket with oil , but not those silver perforated type.
There is a hi temp Sikaflex thats blue and may help.
Go down to a speed shop and have a talk with them

[dom14]

Old school was to wipe the gasket with oil , but not those silver perforated type.
There is a hi temp Sikaflex thats blue and may help.
Go down to a speed shop and have a talk with them

I went to Burson and got Permatex exhaust sealant. Stuff really works. I only applied a very thin layer.
I think it's high temperature silicon with very fine copper dust in it. That's probably what gives them the high temperature resilience as well as orange colour. Sales rep said ideally we are not suppose to use silicone sealant in exhausts(of course)
I reckon the idea of using silver perforated multilayer gaskets is to gasket to fail in case of excessive pressure build up in the exhaust?! If that's the case, makes me wonder whether the two flange gaskets that failed in mine might have something to do with excess muffler pressure build up.
I'll have to do the vacuum test to confirm that obviously.