TD6 Bolt on Performance

Submitted: Wednesday, May 11, 2005 at 11:01
ThreadID: 22890 Views:2150 Replies:3 FollowUps:7
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Spent ages looking at what I wanted to spend my money on to make the 4.2Tdi go better. Being of Scots decent that is no easy feat. Finally shelled out $660 on a new exhaust (justified to SWMBO somehow) and fitted it myself. Fitting the pipes was no problem with the back end on stands and the axle dropped down. The larger dump was fiddly as there is less space for a socket to get onto the nuts and the aircond and other pipes stop a ratchet from swinging too far. This made it harder to get some torque into the nuts. Had to replace several studs as the metal-lock nuts damaged their threads. Also had to bend the fuel tak bash plate on one corner to clear the pipe when at idle. Did this with a large shifter.

Drove out of the shed for the first run and what an immediate difference it made Where the gearing with the 285 tyres felt a bit low before it now pulls smoothly from way low down. ). Does not create any great difference to the noise levels in the car but I am told a bit meatier from outside. The obvious change is that the turbo sounds like it spools up really quick now, like a truck going through the gears. And it pulls like a train in comparison to before.

If you are in the market then no matter what the brand you choose you gotta give this machine better breathing it will really show what it can go like. I was looking at turbo mods/replacement also but after this I don't know if I will be going down that path. I would recommend that you try the exhaust alone first. This one is a 3" mandrel bent system including 3" cast dump pipe from MTQ (no I have absolutely no association with them)

The engine has had nothing else done to it and runs 10psi. Did try a boost controller on its own first but it made little difference even when pushing 15psi (short term trial). That has been removed but will give it another go once I have gotten used to this new exhausts differences.

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Reply By: GOB & denny vic member - Wednesday, May 11, 2005 at 17:00

Wednesday, May 11, 2005 at 17:00
goodday jamie
obviously you have not had time to do a fuel check but its interesting about the turbo lag as i seem to wait ages before the turbo starts working then you get pushed back into the seat like a jet i will watch with interest to see whether you come up with some fuel figures

AnswerID: 110852

Follow Up By: JamieMac - Thursday, May 12, 2005 at 08:31

Thursday, May 12, 2005 at 08:31

Will post fuel comparo once I get some decent figures. Have been keeping fuel records from day one and have been a bit disappointed in comparison to my '89 GQ Td42. On that I was up for about 10.5-11.5l/100km (26mpg) but it did have 280 000km on it so it was well run in. Have not seen figures better than about 12.5 yet on the GU but I have had it from new and it does feel like it runs better each week. I have made allowance for the bigger tyres and when we went to Perth last year I checked the odometer over many staright stretches and the GPS to be a full 10% out even though the speedo is only about 5% out.

The effect of the new exhaust feels like much less go pedal is needed to get over the hump and get the engine pulling. It makes it much quicker through the gears and I am having to stop myself getting to 5th around town now. Corners that involved droppiig to second to pull away cleanly are now a third gear affair. CAnt wait to hook up the camper trailer and see how it all goes!

Needless to say I am impressed. When you check out the difference in the cross sectional area of the two dump pipes it is amazing how the engine reved at all before. The dump pipe would also fit straight up to the original exhaust if you wanted to save a few more dollars but the whole setup was a good price as far as I am concerned. Dump pipe alone would have been around $200-250, 3" straight thru muffler about the same damage plus all the mandrel bends and fittings.

I did look at several manufacturers and local blokes (who were well above this price) and in the end this was the best deal I could get. Dont imagine it matters where it comes from and the exact design its all better than the standard setup.

FollowupID: 367363

Reply By: ADM - Thursday, May 12, 2005 at 12:41

Thursday, May 12, 2005 at 12:41
I have just made and fitted a 3 inch system to my TD6, also noticed the difference in the power. You can hear the turbo spool up were as before there was nothing.

I am also having it tuned to improve the low down responce.
AnswerID: 110992

Follow Up By: JamieMac - Thursday, May 12, 2005 at 13:26

Thursday, May 12, 2005 at 13:26
I am impressed you made your own, was it out of pre-bent tube welded together? Did you prefabricate te dump pipe also from 3"tube? The cast MTQ one comes out at 2.5" and then goes back to the 3" exhaust pipe but seems to work well regardless.

Certainly does make a difference to the way the turbo comes on song. Mine now makes 10psi boost from about 14-500rpm in lower gears where it used to be up around 18-1900 before it reached that level.

Let us know what you do with the tuning to make it even better. I am not sure mine needs tuning but will investigate once SWBO is happy with this mod.

FollowupID: 367408

Follow Up By: ADM - Thursday, May 12, 2005 at 13:48

Thursday, May 12, 2005 at 13:48
I bought the mandrel bends, tubing and fabricated it. It took some time but i enjoy doing those type of projects. I bought the cast MTQ dump pipe, used a double flex ss joint and a balance chamber resonator. The resanator does not restrict the flow of gases but reduces the noise considerably.

The vehicle is being tuned today and will post the results tomorrow.

FollowupID: 367410

Follow Up By: JamieMac - Tuesday, May 17, 2005 at 17:06

Tuesday, May 17, 2005 at 17:06
Any resluts yet Asley? Have been away for a couple of days and may have missed it if in another post

FollowupID: 368011

Follow Up By: ADM - Wednesday, May 18, 2005 at 06:14

Wednesday, May 18, 2005 at 06:14
Yes i have the results but they are home. Will post them tomorrow.

FollowupID: 368099

Reply By: Member - JohnR (Vic) - Wednesday, May 18, 2005 at 06:57

Wednesday, May 18, 2005 at 06:57
Jamie, I was interested to see your post as my 4.2TI ute has seemed like a dead weight with the box on. I saw it as an absolute requirement to do the same conversion. At about 48,000 kms it all of a sudden the engine freed up and it will spin out in first gear with the ute diff ratios too quickly. Perhaps I need the 285x tyres too.

I guess I am waiting on a few things outside my control before I spend money on the performance but would be very interested to see what fuel consumption figures you get. I was told mine would improve with the engine freeing up. I was amazed at the improvement.

Have you had it tuned for the 10 psi boost to compensate for the extra air?
AnswerID: 111737

Follow Up By: JamieMac - Wednesday, May 18, 2005 at 22:07

Wednesday, May 18, 2005 at 22:07

10psi is what it was at standard. I have not adjusted anything other than the exhaust at this stage.

I tried to increased boost only but it made little or no difference in isolation. I suspect if I had the injector pump output increased it would help with the added boost but at an increased fuel use as well.

At std 10psi the exhaust has been enough for the moment. When I get the CT behind and try again in some hilly terrain I will see if she needs a bit more of a fidle.

FollowupID: 368214

Follow Up By: Member - JohnR (Vic) - Wednesday, May 18, 2005 at 22:33

Wednesday, May 18, 2005 at 22:33
Jamie, I guess the fuel:air ratio would suggest some more fuel if you increased above standard to get the benefit. The 4.2 is suggested to have 7-8 psi standard so you are doing well to register 10 psi boost.

I find it interesting getting the lift in output so easily, just by changing the exhaust .., next boost and fuel is so easy.
FollowupID: 368216

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