EXHAUST QUESTIONS ANSWERED BY AN EXHAUST TECH

[Moonman]

Hi Exhaustfix,

I've got a Turboed 1HZ 80 Series. Looks like the guy before me has used 3" steel pipe from the headers to under
the drivers seat where it has been joined using a flexible piece to the original exhaust pipe. The original pipe is
considerably narrower (2" maybe?) but is straight through (no muffler that i can see) is this normally done?
I now have the problem of where the flexible piece is joined to the 3" has cracked. Would i be best to say reweld it,
or to replace the original exhaust with more 3"? Would this lower exhaust temps?

Thanks in advance,
Moonman

[bluemu]

Hi Dr exhuast,

Thank you in advance for answering my questions. I have a few questions, hope you dont mind but I am asking these on behalf of Clubisuzu http://www.clubisuzu.com so I am saving you from about 300 members coming here to ask you the same questions. I will post your reply and Work contact details in our club forum.

We mainly have members who drive Isuzu MU, Wizards, Bighorn. So 2.8 (4JB1T) turbo Diesels and 3.1 (4JG2T) Turbo Desiels. Most run there boost or want to run there boost at about 12psi and some do up to 14 psi.

1) What system do you recommend for each of these vehicles i:e 2.8 and 3.1 turbo diesel.

2) Back Pressure, whats the story, is it a factor or not ?

3) With Mandrel systems, to have a welded sytem or bent system, is there any difference in Performance ? Does it really matter?

4) Please any other interesting things you might like to add for us, perhaps any things you may have discovered while working on these 4x4's


Thank you

francesco

[Dee]

Exhaustfix,

I also have 3.0TD patrol, is going the full 3" requiring mandrel bends instead of say 2 3/4" press bent going to be much difference.
I understand that there is quite a few bends in the patrol's exhaust, and it will benefit from the best flow possible, but I guess what im asking is the difference out of both sizes going to be worth the jump in price or am i going to see similar performance and sound out of both exhausts. (this will be with no resonators, cats or mufflers by the way)

Sorry if that sounds like a stupid question

Well ive spoken to local exhaust shop, and a bolt in 3" mandrel isn't much more expensive than them making up 2 1/2", so i will be going 3".

It doesnt go all the way to turbo, and retains standard nissan cat. The exhaust mech i spoke to said that should remain as it will worsen fuel consumption removing it. Also he said i should retain muffler as 3.0 needs a little back pressure and i would be loosing horsepower removing it.

Any thoughts on this? Should i be replacing dump/removing cat? Put muffler on flanges and make replaceable with straight through pipe?

[EXHAUSTFIX]

hey there.. i got a toyota petrol wit 22r motor... and wondering wats best exhaust? 2 or 3 inch? and make any difference cuttin muffler off

hi there this is a rather low powered engine

i would run a 2" system with a semi baffled muffler

if you remove the muffler alltogether you will have no low down power
you can only do this on a diesel engine

[EXHAUSTFIX]

hi there i have a 300tdi disco with the fuel pump tweaked and more boost would it be advisable to remove front muffler to allow better flow till i get a new zorst?

this would help with power but i dont know how you will go for noise
you might have to replace it with a straight through one

[EXHAUSTFIX]

Hi Exhaustfix,

I've got a Turboed 1HZ 80 Series. Looks like the guy before me has used 3" steel pipe from the headers to under
the drivers seat where it has been joined using a flexible piece to the original exhaust pipe. The original pipe is
considerably narrower (2" maybe?) but is straight through (no muffler that i can see) is this normally done?
I now have the problem of where the flexible piece is joined to the 3" has cracked. Would i be best to say reweld it,
or to replace the original exhaust with more 3"? Would this lower exhaust temps?

Thanks in advance,
Moonman

yes i would replace the flex with a proper braided flex coupling
then run a 3" system with a straight through muffler

this may reduce exhaust temp

ross

[bogged]

I asked once before about the inch system for a GU Turbo Diesel 4.2, and you werent sure on the 3inch dump pipe section.
They are available,

How much for a complete 3in system with 3inch dump for a GU Patrol Turbo 4.2.. I can fit myself if it comes as a kit..

[Clown Boy]

Hi Exhaust fix,

I am putting in a 1uz - 4L V8 and was very exited about my exhaust which has 2 x 2.5" pipes, running through 2 quick flow cats, to 2 mufflers, into a single 3.5" pipe to a third muffler to the back

I got this from a guy doing the conversion who had to stop and sell the bits - long story and irrelevant.

However, I just got told that the twin 2.5" pipes will be too big and ruin my low down torque - is this correct?

The guy I bought from had planned on going twin turbo in the future and was no doubt preparing for that eventuality.

[bluemu]

[rollsy]

hi there,
I have an single cab 85 hilux which i have put a twin turbo 6 cylinder supra engine in. (1ggte)
at the moment i am getting low on funds. So for the exhaust i was thinking i could just run a pipe straight from the turbo and along a bit then into a catylic (spelling??) converter and then just have it dump out somewhere along the side of the vehicle.. this would only be a temporary thing until i can afford a full mandrel system or something..
would this be ok? would i be best going 2 or 3 inch?
any help would be great
thanks heaps
rollsy.

[BadLux]

Hi there,

Another question for you if you don't mind that is. took my 80 series (1997 1hz 4.2D 313,000ks) to get the valve clearances checked and the guy told me that the exhaust is blocked. which goes to show why it has felt gutless.. Question is do I have to replace the WHOLE system headers and all or could I get away with just going from the end of the headers back?

I can actually cup the exhaust with my hand and hold it over it?? This is definitly not right.. I cannot hear any loud leaks but I mean the system is 9 years old and the original mufflers etc.. Is this a common problem with high k's?

Many thanks!!

[EXHAUSTFIX]

Hi Dr exhuast,

Thank you in advance for answering my questions. I have a few questions, hope you dont mind but I am asking these on behalf of Clubisuzu http://www.clubisuzu.com so I am saving you from about 300 members coming here to ask you the same questions. I will post your reply and Work contact details in our club forum.

We mainly have members who drive Isuzu MU, Wizards, Bighorn. So 2.8 (4JB1T) turbo Diesels and 3.1 (4JG2T) Turbo Desiels. Most run there boost or want to run there boost at about 12psi and some do up to 14 psi.

1) What system do you recommend for each of these vehicles i:e 2.8 and 3.1 turbo diesel.

2) Back Pressure, whats the story, is it a factor or not ?

3) With Mandrel systems, to have a welded sytem or bent system, is there any difference in Performance ? Does it really matter?

4) Please any other interesting things you might like to add for us, perhaps any things you may have discovered while working on these 4x4's


Thank you

francesco

hi you have lots of questions ill try my best to give you some help

ok rule of thumb
a 4 cyl normaly asperated engine should need no more then a 2" system or in a few cases where the motor has improvments it may warrant 2.25"
all the systems i build have straight through mufflers depending on how loud u want relates to the size and amount of mufflers most n/asperated cars ned about 2lb back pressure

with turbo cars any thing under 7-10 lb boost 2,5" is fine but any more then that 3" is preferable mandrell pipe work is a litter better on a turbo car than press bending again straight through mufflers

deisel is almost the same as a turbo almost zero back pressure and larger pipe sizes

i hope this helps
ross

[EXHAUSTFIX]

I asked once before about the inch system for a GU Turbo Diesel 4.2, and you werent sure on the 3inch dump pipe section.
They are available,

How much for a complete 3in system with 3inch dump for a GU Patrol Turbo 4.2.. I can fit myself if it comes as a kit..

i will do some investergation and see if there is any thing made yet ill get back to you

[EXHAUSTFIX]

Hi there,

Another question for you if you don't mind that is. took my 80 series (1997 1hz 4.2D 313,000ks) to get the valve clearances checked and the guy told me that the exhaust is blocked. which goes to show why it has felt gutless.. Question is do I have to replace the WHOLE system headers and all or could I get away with just going from the end of the headers back?

I can actually cup the exhaust with my hand and hold it over it?? This is definitly not right.. I cannot hear any loud leaks but I mean the system is 9 years old and the original mufflers etc.. Is this a common problem with high k's?

Many thanks!!

you can do it without headers but diesel manifolds are usually very restrictive run a 2,5" system with a straight through muffler this will work well

[EXHAUSTFIX]

hi there,
I have an single cab 85 hilux which i have put a twin turbo 6 cylinder supra engine in. (1ggte)
at the moment i am getting low on funds. So for the exhaust i was thinking i could just run a pipe straight from the turbo and along a bit then into a catylic (spelling??) converter and then just have it dump out somewhere along the side of the vehicle.. this would only be a temporary thing until i can afford a full mandrel system or something..
would this be ok? would i be best going 2 or 3 inch?
any help would be great
thanks heaps
rollsy.

run a 3" on this but u will need a muffler they are very loud

[EXHAUSTFIX]

Hi Exhaust fix,

I am putting in a 1uz - 4L V8 and was very exited about my exhaust which has 2 x 2.5" pipes, running through 2 quick flow cats, to 2 mufflers, into a single 3.5" pipe to a third muffler to the back

I got this from a guy doing the conversion who had to stop and sell the bits - long story and irrelevant.

However, I just got told that the twin 2.5" pipes will be too big and ruin my low down torque - is this correct?

The guy I bought from had planned on going twin turbo in the future and was no doubt preparing for that eventuality.

it is a little big but if you are going to turbo it later dont waist your money on it now as you will have to change the system when you put on your turbo,s

[bogged]

I asked once before about the inch system for a GU Turbo Diesel 4.2, and you werent sure on the 3inch dump pipe section.
They are available,

How much for a complete 3in system with 3inch dump for a GU Patrol Turbo 4.2.. I can fit myself if it comes as a kit..

i will do some investergation and see if there is any thing made yet ill get back to you

Thanks dude, appreciate your assistance..

[troll85]

hi ross
i have a turbo diesel 60 series. im currently running a 3 inch exhaust straight through without muffilers is this the best for power and sound or should i reconsider

thnx Rik

[EXHAUSTFIX]

hi ross
i have a turbo diesel 60 series. im currently running a 3 inch exhaust straight through without muffilers is this the best for power and sound or should i reconsider

thnx Rik

hi there
this is perfect for power
with the sound its your choise but if its a little loud just add a small straight through muffler this will not rob any power

ross

[GQ96]

Hi Ross,
Would extractors off a Patrol GQ 4.2 Diesel go onto a patrol gq 4.2 petrol? And if it does, how much would i be looking at for someone to fit them and 2.5inch exhaust that comes with it?
Thanks
Glenn

[bogged]

Hi Ross,
Would extractors off a Patrol GQ 4.2 Diesel go onto a patrol gq 4.2 petrol?

Yes they do.

[EXHAUSTFIX]

Hi Ross,
Would extractors off a Patrol GQ 4.2 Diesel go onto a patrol gq 4.2 petrol? And if it does, how much would i be looking at for someone to fit them and 2.5inch exhaust that comes with it?
Thanks
Glenn

yes they do fit they have the same head pattern
you should oay no more then about $80 -$100 to get them fitted and about
$240 for a system


ross

[deanchristensen0001]

EXHAUST FIX
Again thanks for all your help

I am installing a DieselGas LPG system on my Turbo Diesel 3.0 lt Patrol. I need to remove the central Muffler to allow for the installation of a 30 lt gas tank.

I have been told that removing it presents no problems and the sound only increases slightly, is this correct? What be your recomendations

Secondly I have read through all of the posts and understand that a smaller system pipe retains good low down torque, but should I put a 2.5" or 3" dump pipe on to improve turbo spool up time and get me of the line a little quicker.(turbo lag is terrible when I'm trying to pull out into moving traffic from a side street)

Thanks for your genorosity

[nicbeer]

Hey Exhaust Fix,

I have a sierra with a 1.3, extractors and 2" system inc no resi and 1 turbo muffler,

I am going to do a 1.6 16v efi conversion very soon and was wondering if that size was ok for the engine inc extractors. should i put a resi in there or not.

Guessing the noise factor will be the same between the 1.3 carb and 1.6 efi?

Thanks

Nic

[Goatse.AJ]

Hey Ross,

great service you're providing here

I'm currently running a standard exhaust mainfold and cat with 2" system from Cat back. Got a heap of extra torque down lower (running an Applause engine in the Feroza) when I went to the 2" system. Starts pulling around 2600 rpm vs. 3100rpm previously.

I still have my new extractors (4 -2-1) under my bed .... the ex has severely sapped my mods budget

My Cat is knackered, so was hoping to run a Commodore V6 Cat (2nd hand from a wrecker) and the extractors.

Two questions:

Should I go the Commo Cat? Or is it too big?

and

What sort of dollars am I looking at for you to fit the Cat? (I can fit the extractors.... gotta keep the cost down as much as possible )

[oscar]

Exhaustfix,

i have GU Patrol Wagon 2.8lt Turbo diesel. Factory turbo and intercooler.

Primarily looking for more bottom end torque. Increase in general kW would also be good.

I've spoken to a few exhaust shops gut they all have a different answer. 3" dump to 3" system. 2 3/4" dump to 2 3/4" system. 2 3/4" dump to 2 1/2" system. A variety of different muffler suggestions too.

Would like to know what you suggest. What sort of $$$ should i expect to pay?

Will be putting Unifilter in soon. May upgrade turbo at later stage.

Would like a good note but not rediculously loud.

Are there any good kits available...could fit myself. Do you do kits?

Thanks.

[bogged]

I asked once before about the inch system for a GU Turbo Diesel 4.2, and you werent sure on the 3inch dump pipe section.
They are available,

How much for a complete 3in system with 3inch dump for a GU Patrol Turbo 4.2.. I can fit myself if it comes as a kit..

i will do some investergation and see if there is any thing made yet ill get back to you

any word?

[EXHAUSTFIX]

EXHAUST FIX
Again thanks for all your help

I am installing a DieselGas LPG system on my Turbo Diesel 3.0 lt Patrol. I need to remove the central Muffler to allow for the installation of a 30 lt gas tank.

I have been told that removing it presents no problems and the sound only increases slightly, is this correct? What be your recomendations

Secondly I have read through all of the posts and understand that a smaller system pipe retains good low down torque, but should I put a 2.5" or 3" dump pipe on to improve turbo spool up time and get me of the line a little quicker.(turbo lag is terrible when I'm trying to pull out into moving traffic from a side street)

Thanks for your genorosity

WITH A TURBO DIESEL IT IS different than a norm asperated
you can put a 3" dump pipe on it and get better spooling
and yes you can remove the front muffler if it is a bit loud just put a good resenator in the rear
ross

[EXHAUSTFIX]

Hey Exhaust Fix,

I have a sierra with a 1.3, extractors and 2" system inc no resi and 1 turbo muffler,

I am going to do a 1.6 16v efi conversion very soon and was wondering if that size was ok for the engine inc extractors. should i put a resi in there or not.

Guessing the noise factor will be the same between the 1.3 carb and 1.6 efi?

Thanks

Nic

not a lot of differance between the two
a reso is only for noise factor
you should be able to use same system

[EXHAUSTFIX]

Hey Ross,

great service you're providing here

I'm currently running a standard exhaust mainfold and cat with 2" system from Cat back. Got a heap of extra torque down lower (running an Applause engine in the Feroza) when I went to the 2" system. Starts pulling around 2600 rpm vs. 3100rpm previously.

I still have my new extractors (4 -2-1) under my bed .... the ex has severely sapped my mods budget

My Cat is knackered, so was hoping to run a Commodore V6 Cat (2nd hand from a wrecker) and the extractors.

Two questions:

Should I go the Commo Cat? Or is it too big?

and

What sort of dollars am I looking at for you to fit the Cat? (I can fit the extractors.... gotta keep the cost down as much as possible )

the only thing with a comodore cat it is a lot bigger and may not fit in the car you need to look at aviable space
about $50 to fit