Outer Limits 4x4 Board

There's some good advive above, I'd be going for a 3" dump pipe, and i'd also be trying to make sure that the adapters that go from the turbo to the dump pipe are as smooth as possible, bellmouthed if you can (no sharp egdes, shitty welds or steps as these will cause eddys and provide restriction) - all of this applys to the intake side also.

If you were short on funds just go for the 3" dump pipe, 3" muffler then go back to 2.5" to the back of the car, as the gas cools down it will require less space, which is why the dump pipe is important - hot gas takes up a lot more room than cold.

Remember what makes the turbine spin, pressure drop between the engine side and the exhaust side of the exhaust housing, so if you increased the restriction at its exit the turbine won't spin as fast, decrease the restriction and it spins faster - quicker spool up and less heat.

I think you hit it square on the head there patroler.

fisho64 wrote:I think you hit it square on the head there patroler.

How many different ways can it be explained. You showed a reluctance to believe a word I was saying and then with exactly the same thing explained in a slightly different way you finally agree.

dont get snappy, I was talking about the pressure differential and he's not talking about 3" all the way is he??
You show a reluctance to believe a word I say also, thats why forums are great, for different viewpoints.
I still say that 3'' mandrel bent exhaust on a 2.8 hilux is an un necessary expense. How much will that set you back, especially if you dont have the flange and dump pipe to start with? I'll guess and say $1000. Maybe someone can correct me.
I also understand something about these things, Im a marine engineer, not just a dummy off the street

uninformed wrote:i have a 3 inch mandrel bent system on my 2.5ltr tdi landrover. it made a big difference over the 2 1/2 factory system. flat out with my trailer on was 108km/h now about 130km/h and the turbo spools quicker meaning i'm not changing down all the time. it runs 17psi of boost
cheers,serg

An over kill???

As with anything though you pay for what you get and you get what you can afford.

fisho64 wrote:Turbos dont produce horsepower, they contribute to an engines ability to produce it. (or increase its efficiency in the case of a diesel) It cannot be quantified without knowing what is attached to etc. A statement like that is overly simplistic.
Beware of what you are told by someone who is selling you something.

flowing a turbo is just like flowing a cylinder head. a given amount of flow is capable of a given amount of HP.

But if the thest of the setup is up to the task it will not make that power.
that does not mean the turbo can not flow that much air.

when making that statment i was stating the maximum hores power posible with that turbo. If the engine was capable of flowing more air the turbo would be restriction. wich we actualy proved with my bosses car, that used that turbo. the turbo was rated at 400hp the engine made 390hp. then after fitting a turbo rated at 500hp the engine then produced 450hp.

ask toughnut. i'm pretty sure he has seen the dyno numbers.


and as for john telling us some thing just to sell a turbo. i don't think so.
again ask toughnut. he has delt with john a few times..

when you sell and fit the things come and talk to me about it

fisho64 wrote:dont get snappy, I was talking about the pressure differential and he's not talking about 3" all the way is he??
You show a reluctance to believe a word I say also, thats why forums are great, for different viewpoints.
I still say that 3'' mandrel bent exhaust on a 2.8 hilux is an un necessary expense. How much will that set you back, especially if you dont have the flange and dump pipe to start with? I'll guess and say $1000. Maybe someone can correct me.
I also understand something about these things, Im a marine engineer, not just a dummy off the street

the difference in the cost would hardly be more then maybe $50. the pipe is the same cost. the muflers maybe slightly more but that depends on where you go

Well just made a quick call out of curiousity to a perth exhaust place carline in malaga and he said straight away cost of 2 1/2" as opposed to 3", double and not worth it on an engine that size? Of course there will be some improvement, however minor. But if you have to put it on a dyno to tell then maybe it aint worthwhile.
However if you can get it for $50 extra then good luck and do it!!
Also UNINFORMED is running 17 psi boost. Dont know anything about the 2.5 landy but you'd be brave to do that on a 2.8 hilux, especially without intercooling

uninformed wrote: it runs 17psi of boost

Just noticed this serg - do you have an egt and what temp does it get to if so. How long have you had it at 17psi?

no egt yet, on my to do list. i do drive it fairly conservatively. i was told by my mechanic that the 300tdi runs 16-17psi boost the 200tdi's were about 15 psi. when i had the exhaust done by tipan xp, they are 5 doors down from my LR dedicated mech, they worked in with each other and re set the fueling and check the egts. mech said that it wasn't getting that hot and was cooling real quick. this guy use to work with Mal story and i believe is very good. it uses a bit more fuel but with my 8 x5 dual axle trailer on all week i get 500km's out of 60 lts
cheers, serg

dunno who's doing your exhaust quotes but 3" mandrel bent exhaust for my turbo cruiser including muffler was less than $600.

$350 for the 2 1/2" $700 for 3"
My 2 1/2" last year actually cost $280

fisho64 wrote:$350 for the 2 1/2" $700 for 3"
My 2 1/2" last year actually cost $280

Was that 21/2" mandrel bent? If not you also need to take into account the loss through having press bends in the tube. I know it seems we're splitting hairs but it makes more of a difference than a lot of people think.

OK here is a pic of my dump pipe.
Should I go A and cone out the pipe directly at the outlet or B down the pipe after the bend?

It's is better to cone it straigh off the flange but to save about $45 you could do it straigh after the bend. Just had another look at the pic. You have a reducer welded straigh on the flange at the moment. Just cut the pipe off the flange and go 3" from the flange.

Hi all...Ive got a 79series 1HZ with a MTQ turbo fitted,I wondering if i would get much of a power gain and a lower EGT if i just replaced the standard muffler and replaced with a straight thru muffler.Im not after every last dropp of power,and it would be a shame to ditch a perfectly good exhaust system.

You would get a power gain but the real benefit is how the power is delivered. Having less back pressure straigh after the turbo means that the turbo will spool up easier, earlier and for longer. Your "power band" would be increased so it would produce power from lower in the rev range which makes it more drivable. EGT would only have a marginal reduction, most of the gains in EGT are made by cooling the intake air temps through intercooling etc. When your MTQ turbo was fitted did they fit their dump pipe (small pipe imediately after the turbo) as well? If so Just changing the muffler or ditching it all together would probably be enough for you.

Hi all...Thanks toughnut...I bit the bullet and booked in for a 3inch system with straight thru muffler...$550.00 fitted...goes in Thursday...ill lett yous know how much difference.

Hi all...I got the 3inch exhaust fitted,It does go better,i expected a bigger power increase,but it does go noticably better though.

mickbeny wrote:Hi all...I got the 3inch exhaust fitted,It does go better,i expected a bigger power increase,but it does go noticably better though.

You may find that you can increase the fuelling a bit more, now that you are getting more air through the engine.

when changing to a 3inch exhaust and straight through muffler on a 4.2 td do you get any increase in noise or droning over standard?

Depends on what length it is. I do with mine finishing just behind the cab but Other guys with it finishing at the rear of the vehicle don't have the same problem.

Hi all...Chips,I said to the exhaust guys to keep my exhaust quiet as possible,and they did.definately no droning,but is louder than standard and gets quieter with higher the revs.If the engine labours it gets louder.but all in all its far from noisy.

thats why under qld trans laws, anyway that turbos are classed as a muffler, so as long its below the Db test, u don't need one

Hi all...BTW,the engine runs heaps smoother.

chips59 wrote:when changing to a 3inch exhaust and straight through muffler on a 4.2 td do you get any increase in noise or droning over standard?

I've been in one and it was quite load outside and droned inside.
A mate did his and put a resonator on it and it is quiet. Just a little over standard, goes great.

how does enlarging the dump pipe effect fuel efficency.
I read that by reliving the presure more fuel can enter the enginie.
Does that mean it chews up more fuel.
I have got a 2.7 turbo desieil terrano and am just waying up all the options for a new exhaust

I am thinking of upgrading my exhaust system in the GU TD42T and is swayed towards a 3" dump pipe all the way through.... any idea how much that will cost and if 3" is the ideal for a TD42T.

I am in W.A.

Get your ddump from MTQ about $185 im told
Get the exhaust done local with a few flanges incase you need to replace part of it from damage.
Definately the way to go, i will be soon...

Hi all. Just going to throw my 2c in. My mate's got a GU Comp truck, with a 4.2 TDi, and for his exhaust (3inch mandrel bent) it cost a bit over $700. Thats from the dump to about 400mm past the cab. I got a quote for my MK, and it was well over $700 for a 3inch mandrel bent setup.

I've just bought an MK ute, and i'm going to make my own 3 inch exhaust out of mandrel bent sections, from 20mm past the dump flange, to about 350mm past the cab, (Legal limit is minimum of 300mm past cab). Also will be running a small intercooler (R32 Skyline), and a pyrometer too.

Less back pressure = cooler exhaust = less work for exhaust turbine. (and also leaves a choice of winding fuel pump up)

Coxy