Exhaust on 300tdi

[110 Pete]

Hello all,

I am planning on getting a straight through exhaust put on my 1994 300tdi Defender but I am not quite sure what size and what configuration to go for.

I am tossing up between 2.5" or 3" Straight through pipe. Would the 3" have too little back pressure resulting in MORE turbo lag?
I am after the turbo to spool up faster (i realy want it to be spooling slightly when idleing like when I took my centre box out for a clean and ran it with the pipe straignt from the turbo :twisted:). I am also after better low end torque and less turbo lag.

I do not want the exhaust to drone when cruising on the Highway but I would still like it to sound a bit meatier than stock. Should I run a Hotdog on the tip or a straight through Muffler on the end?

Anyone who has done this your advice would be much apreciated.

Cheers

Pete

[weeds]

i went for 2.5" normal bend with no mufflers, cheap as chips........

i believe the turbo spools up quicker but hard to tell what if any increase in power and torque...........without putting your rig on a dyno before and after your exhaust mods i say most guys want to bleieve there is an increase just because they have done the mod. i have had mine dyno'd a couple of times but never before and after each mod

do you monitor EGT's? if you have tweaked the fuel pump i would suggest installing an EGT guage

I should have kept the resinator which sits behind the rear wheel, as i can hear the 'drone' if the rear passanger window is down, more so on freeways when there is concrete barriers beside you. Its not really that bad and i have gotten used to it

[110 Pete]

i went for 2.5" normal bend with no mufflers, cheap as chips........

i believe the turbo spools up quicker but hard to tell what if any increase in power and torque...........without putting your rig on a dyno before and after your exhaust mods i say most guys want to bleieve there is an increase just because they have done the mod. i have had mine dyno'd a couple of times but never before and after each mod

do you monitor EGT's? if you have tweaked the fuel pump i would suggest installing an EGT guage

I should have kept the resinator which sits behind the rear wheel, as i can hear the 'drone' if the rear passanger window is down, more so on freeways when there is concrete barriers beside you. Its not really that bad and i have gotten used to it

Hi Weeds,

Thanks for the helpful reply! A few questions does your turbo spool on idle and is your drone bad just on the highway?? Is it heard in the cab and reverberates?

I am going to get an egt gauge as soon as possible but I am also getting a straight through to lower the temp as my fuel pump has been tweeked and my turbo is already spooling up fast.

Oh and is the exhaust note deeper and meatier than with stock, if you get what I mean :P

Cheers

[weeds]

A few questions does your turbo spool on idle i don't believe so
Is your drone bad just on the highway?? yes >90km/hr
Is it heard in the cab and reverberates? only heard if the rear window is down, if front passenger window is done you can just hear it

I am going to get an egt gauge as soon as possible but I am also getting a straight through to lower the temp as my fuel pump has been tweeked and my turbo is already spooling up fast.

Oh and is the exhaust note deeper and meatier than with stock, if you get what I mean :P there is an increase in noise.....i haven't really heard it as when my girlfriend drives off she doesn't really put the boot in

Cheers
HTH

[Landie333]

I am tossing up between 2.5" or 3" Straight through pipe. Would the 3" have too little back pressure resulting in MORE turbo lag?
I am after the turbo to spool up faster (i realy want it to be spooling slightly when idleing like when I took my centre box out for a clean and ran it with the pipe straignt from the turbo :twisted:). I am also after better low end torque and less turbo lag.

In a forced induction engine, the backpressure of the exhaust is created by the turbo. The collector is before the turbo which is where your scavenging effect is created.

After the turbo, you pretty much want the gasses gone ASAP. Backpressure after the turbo isn't good, but having the largest exhaust isn't great either. You want the compromise between backpressure and gas velocity.

For a forced induction engine after the turbo, gas velocity is important. Whereas in a naturally aspirated engine, backpressure is more important. Realisitcally, a transitioned 3'' turbo back would be a good size. Plenty of people run 3'' on 2-2.5L engines with good results.

Things to consider with an exhaust is firstly, transitioning. the turbine housing, for example, may be 2.5" putting a 3'' straight into that will cause a drop in gas velocity resulting in higher temperatures (at that point) The lowering of gas velocity means you are effectively creating backpressure aswell.
Secondly, Bends. Mandrel bends are more effective as the bends are smooth. Not with low and high points through the bend. Results are the same as above. On that aswell, the radius of the bends is important. Having sharp bends results in gas velocity slowing. The straighter the bends, the more efficient it should be.

If you are looking at doing it yourself, have a look at this website:
Tube Bending & Fabrication - Columbia River Mandrel Bending (http://www.mandrel-bends.com/catalog/)
I havn't personally used them YET. But I know of people that have and have made nice exhuasts out of them.

Keep us posted:)

[dromader driver]

I put a hot dog in to replace the under floor muffler after it fatigue cracked. Definitely pulls better on my calibration hill. The kids have a spare cannon kicking around that I keep threatening to put on instead of the rear resonator.

Exhaust is off at the moment for a clutch fork change and it was very interesting to see the thickness of soot inside the pipes.

Will be interesting to see what that sounds like with the cannon. :cool:

[newhue]

Isn't standard 60mm diameter, so a 2.5" is basically the same. I know I put a 2 and 3/4" on a 3l to replace the original 2" system and the results were minimal. It held itself better on hills parhaps, but that was the only noticible effect, apart from more drone and the $1100 bill.

To put it in context, I just bought a second hand tail pipe for a Tdi for $50.

[weeds]

my straight through cost $200 band new, i wasn't really looking for performance just wanted a simple exhaust........oh the main reason for fitting it was to accomodate my PTO drive

[110 Pete]

my straight through cost $200 band new, i wasn't really looking for performance just wanted a simple exhaust........oh the main reason for fitting it was to accomodate my PTO drive

Weeds, how did you get it so Cheap!! Ive been quote $600 3" straight through with Hotdog on the end with madrel bends! Ive also been quoted $1200 which I thought was ridiculous as i only asked for a pipe, no mufflers or anything!!:eek:

Landie333, that was very helpful!! So you would put a 3" on the 300tdi?? Id love to build my own exhaust, only problem is I cant weld:(

Dromader Driver, tell me more about your system!:)


Thanks guys

Pete

[Landie333]

Landie333, that was very helpful!! So you would put a 3" on the 300tdi?? Id love to build my own exhaust, only problem is I cant weld:(

From what i've seen on other makes (predominatly petrol engines) 2-2.5L forced induction engines have had good results with 2.5'' and slightly moreso 3'' exhausts. I've never played with exhausts on 300TDIs, so I can't comment on what effect it will have on a 300.

I had a chart somewhere showing the theoretical exhaust sizings in relation to engine size and I can't find it. But from memory, 2.5'' was upto about 3ish Litre engines. If my memory serves me correctly.

Buy a cheap welder (if you can afford it) and learn. The only way you will learn is by doing it. Atleast with a supplier like Mandrel Bends, you can buy plenty of bits, destroy them and still not have spent too much.

A thing to consider, measuring up the lengths you need, purchasing the bits from them and then paying someone to weld it up. $1100 for a exhaust sounds right, but so does $200. It really depends on where you go and who you know. Shop around.

[weeds]

Weeds, how did you get it so Cheap!! Ive been quote $600 3" straight through with Hotdog on the end with madrel bends! Ive also been quoted $1200 which I thought was ridiculous as i only asked for a pipe, no mufflers or anything!!:eek:


Pete

it was probably cheap because it was only a piece of pipe with normal bends......no mandrels, hotdogs....it did include a piece of flex pipe

[schuy1]

I just got the center muffler replaced - $60 - left the stock resonater as it is straight through, did that 13yr ago and its been good. Noticed a slight improvement in takeoff and on steep hills, but that soon fades into the background :D Main reason got it done was to stop sticks hanging up on it, works! :D Why would you need to replace whole system? mines a 96 model and its still like new! Unnecessary cost me thinkith :) its not like u need to run the 1/4 12 tenths quicker!

[weeds]

I just got the center muffler replaced - $60 - left the stock resonater as it is straight through, did that 13yr ago and its been good. Noticed a slight improvement in takeoff and on steep hills, but that soon fades into the background :D Main reason got it done was to stop sticks hanging up on it, works! :D Why would you need to replace whole system? mines a 96 model and its still like new! Unnecessary cost me thinkith :) its not like u need to run the 1/4 12 tenths quicker!

agree, at first i just removed the centre muffler............but when the tpo come along they said it was easier to replace the lot

[schuy1]

Ahh, oki well you got it at a good price any way so no grief in that :) But I dont think I would bother for a "road: going machine again unless it was destroyed by some mishap or as part of other upgrades \
cheers Scott

[ugu80]

https://www.terrafirma4x4.com/products_php.php?cat=24&grp=93

[rick130]

http://www.aulro.com/afvb/technical-chatter/24016-got-my-new-exhaust-3-straight-through-no-muffler.html

http://www.aulro.com/afvb/90-110-130-defender-county/97186-exhaust-options-300-tdi-2.html

http://www.aulro.com/afvb/90-110-130-defender-county/162342-300tdi-3inch-exhaust-required.html

http://www.aulro.com/afvb/technical-chatter/135954-2-5-3-exhaust-300-tdi.html

http://www.aulro.com/afvb/technical-chatter/36719-fao-rick-exhaust-finally-done.html

[110 Pete]

http://www.aulro.com/afvb/technical-chatter/24016-got-my-new-exhaust-3-straight-through-no-muffler.html

http://www.aulro.com/afvb/90-110-130-defender-county/97186-exhaust-options-300-tdi-2.html

http://www.aulro.com/afvb/90-110-130-defender-county/162342-300tdi-3inch-exhaust-required.html

http://www.aulro.com/afvb/technical-chatter/135954-2-5-3-exhaust-300-tdi.html

http://www.aulro.com/afvb/technical-chatter/36719-fao-rick-exhaust-finally-done.html

Thanks Rick!! I am even more in two minds than I was before after reading those!:p
I do like Defender200tdi FAO Rick thread, makes me wana go to 3" :twisted:

UGU80 - i have seen the TF pipes, Id like to get the whole system done though

Landie333 - Id love to learn to weld but due to comitments dont have the time at the moment to

Im hearing mixed responses from lots of people, Some swear by 3" on the 300tdi, some think 2.5" is the go as well :P

Is there really that much in half an inch??

Thanks for the reples guys!:)

Pete

[slug_burner]

About 40% more cross sectional area, sounds like a reasonable improvement to me.

[110 Pete]

About 40% more cross sectional area, sounds like a reasonable improvement to me.

Slug_burner, what do you think 2.5" or 3" :D

Pete

[110 Pete]

Oh I forgot to ention earlier my fuel pump has been adjsted and my Boost runs a bit higher than standard at 15-16 PSI :)

[slug_burner]

Slug_burner, what do you think 2.5" or 3" :D

Pete

It comes down to what you want and what you are prepared to pay for. To the average person 3" probably would not make a difference they would be prepared to pay for. For someone who tinkers with their fuel pump and performs other mods to try to improve performance then I think the 3" is the way.

[rick130]

Without any empirical testing I'd suggest a 2.75" pipe would be 'ideal' but 3" works well without any potential problems (so far that I'm aware of) in probably a combined several million km's of use from all of us that have had one made/made one.

[110 Pete]

Well after reading lots and lots and lots of various sites and threads i think I may have come to a conclusion! Maybe if I had a 4.2L pootrol I'd go a 3" but on the defender with the outlet on the turbo/exhaust that is an extra .5" either side!! :eek:

My decision is leaning towards 2.5" or 2.75" from the turbo, with a hotdog in place of the centre muffler and a straight through Resonator on the rear maybe with a 3" tip:wasntme:.

What do you guys think :)

Pete

[slug_burner]

What is the tip going to do?

Your tolerance to noise will tell how good your hot dog resonator selection will be.

[two up]

Have you thought about a 3" dump pipe into a 2 1/2 or 2 3/4. The most important part of a performance exhaust system is the first 3 feet.

[110 Pete]

What is the tip going to do?

Your tolerance to noise will tell how good your hot dog resonator selection will be.

The tip will be there for no purpose but to look cool and make it look like a big exhaust:wasntme: but no real purpose haha!

[rick130]

[snip]

I'd go a 3" but on the defender with the outlet on the turbo/exhaust that is an extra .5" either side!! :eek:


[snip]

What do you guys think :)

Pete

Err, the dump damned near matches a 2.5" pipe (and does with a little massaging from a die grinder)
It's no where near as small as 2".

A nice 2.5" to 3" transition is relatively easy.

I just turned a swaging/flaring die up out of some bar and swaged up some 2.5" pipe to 3" for the transition.

[110 Pete]

Err, the dump damned near matches a 2.5" pipe (and does with a little massaging from a die grinder)
It's no where near as small as 2".

A nice 2.5" to 3" transition is relatively easy.

I just turned a swaging/flaring die up out of some bar and swaged up some 2.5" pipe to 3" for the transition.

Yeah the dump pipe is 2.25" same as the outlet on the turbo. So Rick you think a 3" dump pipe dropping down to 2.5" or 2.75" at the hotdog??

What would your preference on my set up be?:)


Cheers

Pete :)

[rick130]

IIRC the cast dump on the turbo is 60mm so I opened mine up to 2.5" to match a 2.5"-3" tansition I made (15* taper for reasonable flow) and ran 3" all the way.

Just make sure you use a good size muffler and a resonator at the back.
My main muffler is undersized and it's tiring on a trip.
Cruising @ 100/110km/h isn't so bad, but the noise as you open the throttle for any sort of incline or hill climb or taking off from a stop......:angel:

[110 Pete]

IIRC the cast dump on the turbo is 60mm so I opened mine up to 2.5" to match a 2.5"-3" tansition I made (15* taper for reasonable flow) and ran 3" all the way.

Just make sure you use a good size muffler and a resonator at the back.
My main muffler is undersized and it's tiring on a trip.
Cruising @ 100/110km/h isn't so bad, but the noise as you open the throttle for any sort of incline or hill climb or taking off from a stop......:angel:

Can you post some photos of you exhaust with some captions??:)

Cheers

[Defendozer]

Well after reading lots and lots and lots of various sites and threads i think I may have come to a conclusion! Maybe if I had a 4.2L pootrol I'd go a 3" but on the defender with the outlet on the turbo/exhaust that is an extra .5" either side!! :eek:

My decision is leaning towards 2.5" or 2.75" from the turbo, with a hotdog in place of the centre muffler and a straight through Resonator on the rear maybe with a 3" tip:wasntme:.

What do you guys think :)

Pete I would be going with either of those sizes, I've played around with a few different exhaust systems on 300Tdi's and can say you will most definitely want to be putting a resonator at the rear of the car, without one the drone does get very annoying on longer trips (even short ones to actually!). I would say leave the middle pipe section without any muffler and see how you like that, its not hard to get it off and put one on (or get one put on) if you think you need it. But from my experience I've found leaving the middle one out just gives a little more of a noticeable turbo whistle not an increase of droning noise!!
That's just what I reckon:p

Let me know what you decide:)

[110 Pete]

Hey Defendozer,

Im going 2.5 straight through with a single straight through resonator at the rear.
Can't wait to free top end revs up and get the temp down a bit:)

Pete