Right, few questions about this..

1. Has anyone on here done it to a 1.4 tdi?
2. Is it likely to make much difference?
3. Is it worth the hassle, and will it make it sound worse than it already does (diesely!)?

MOT is coming up in a few days, and been thinking about this once it's done.

Also, any other little mods? Obviously could really do with a full exhaust to get best gains. But I don't have a clue about diesels, do people use panel filters on them and things like that?!
Obviously there is FMIC, exhaust, remap etc. none of which i would consider apart from remap, but i would really like to see what other people have got, gains achieved, and what they recommend?

Thanks very much!

your not gonna get any better exhaust wise than a bigger diameter straight through pipe on a TD, the less restrictions the better so a de-cat is a good start although coupled with the standard size pipe and any back boxes i doubt it would make much of a difference.

a decent filter is never a bad thing on any engine, again probably no real gains to be had there.

FMIC is pretty pointless unless your going all out on it, most of the time it just seems people use them to show every one that they have a turbo on their car

my mates just fitted some kind of tuning box on his TDI passat and that's made a big difference, might be worth looking into? cheaper than a remap.

Don't think a de-cat exhaust would ain you any power, it would remove some restriction in the exhaust system so may give faster turbo spool and therefore less lag.

The more air you get into a deisel engine the more powere you will have, so high flow filter/pipework is a good idea, but you need more fuel to make use of said air increase, so a remap is essential for any significant gain. I'm running a pipercross panel filter with a larger airbox snorkel.

FM Intercooler probably not nessecary without a turbo upgrade, it may give more efficient air cooling but putting it on the front means more pipework and usually larger cooler. All this is just more volume for your turbo to pressurise, increasing lag and putting more strain on your stock turbo. I have a side mount intercooler from a 1.8T passat, seems to pull for longer into the revs than before, especially on longer periods of acceleration (ie motorways).

The tuning boxes that are mentioned above tell your ECU to shove more fuel in i think, will give power gains, but dunno how good they are for the life of your injectors, which are well pricey to replace.

If you want easy gains I'd get a panel filter, de-cat, get rid of your EGR and then get it mapped.

Thanks very much, that's exactly the response i was looking for. I am looking for easy, quick, cheap gains without any less reliabilty, mpg etc.
I think to be honest, just a remap would do! But was wondering (partly because my air filter needs changing) if a panel filter and decat would do anything, and if it would make it sound like a moped!

Cheers mate.

Also, McLOVIN, heard about those cheap tuning boxes. There a A LOT of very mixed opinions about them! Some say it will ruin the fuel pump etc etc.! I think i will just wait and get a remap. To be honest i don't want to go over 100bhp anyway, and a map will do more than that on its own so anything else is pointless!

Thanks again

MPG shouldn't be affected dramatically, thats mainly down to how you drive, so expect a reduction after a remap

There's no hiding the diesel sound though, your car will sound like a tractor, and will only get louder. There is however some pleasure to be had in smoking some scally punto or clio in a car that sounds like a bag of spanners falling down some steps, then flashing the 'TDI' badge as you pull away from them...

Haha, i've been having quite a lot of fun with it already, they are quite nippy standard! I guess a remap makes a BIG difference in power? Sure it must have been asked before but where do people recommend for them? Where was yours done, and how much? They do seem quite expensive

Cheeers

Mine should have been £300ish I think but I got it cheap, which is about the same as a full exhaust sytem, but you'll see a better increase in power from a map so relatively speaking it aint too pricey. cant really help you with where as your down south by a long way from where I am, might be worth finding someone in your area (must be people on this forum) who have had a decent map done, and take it there.

Its not just a gain, its how the power is delivered; standard the power spikes at 2200-2500 revs and dies away pretty fast meaning you have to change gear to keep it in the narrow power band, a decent map should see it pulling well to 3500 (or more) revs. Dont get me wrong though, its still a 1.4 polo, so dont go expecting miracles, but it does make it a hell of a lot more fun to drive.

Haha yeh, i see what you're saying! I will look into it more, and ask around, cheers

my 9n 1.9tdi is about 150bhp and has no literally a pipe for the exhaust, no cat or backbox and i still return 57.6mpg on a 25 mile trip

and the cat removal made no difference in my opinion, maybe just hear the turbo spooling a tiny bit more. try the back box of it lol, dont know what it would sound like on a 1.4tdi though

You took the back box off? Is this a normal thing to do?! lol Must just be really loud surely? Lol but made a difference to performance?

i just took it off for a bit of sound.

if prolonged useage it can shorten turbo life due to loss of back pressure therefore the turbo "stalls" making a cooing sound.

mine does not coo and yes it is quite loud but only when flooring it about.

in my opinion i think the throttle is more responsive and turbo spools up a bit quicker.

and second reason i took it off is because i couldnt at that time afford the larger downpipe and hi flow cat system. thats the next thing on the cards

cheers mate, car sounds cool. Don't think i'm gunna go for big power. Can't be bothered with the problems it causes! clutch etc. And to be honest its not worth wasting time/money/compromising on mpg/reliability etc. when a simple remap where i can drop the car off and 2 hours later i'll have 100bhp and decent driveability with no compromises, and no risk to my insurance!

..then save up for schmidts haha

Thanks very much for the advice anyway top man.

good man, no point in trying for power with a 1.4 tdi, no offense intended but you see where I'm coming from.

person from NI i know has a 236bhp bora and he still returns 49mpg

get a straight through system for it matey. I made one for my tdi and it made the world of difference, dont get me wrong, as said above its a 1400 so dont expect miracles.

But it is deffinately smoother exceleration, with it on and you can certainly feel theres less restriction on the turbo. As for MPG didnt make a difference, next on the cards is 2.5" turbo back to the existing system and then a remap, should be seeing 100 -115.

Believe there was a guy on here a while back when i joined that done said mods but also took the injectors off of a golf gt tdi 150 and was seeing something like 125 - 130 bhp from the car with out much change to reliability and mpg didnt cange. So you can certainly get a decent figure out of these matey, but the most important thing to consider is the torque, you can have all the power in the world put if your car cant implement it then theres no point having it, and after a remap the torque levels rocket so your tdi will be bale to implement the small power it has well.

turbo stall doesn't affect diesels at this level of power, they dont have throttle plates that close like petrol engines so there isn't really ang 'back pressure' when changing gear or lifting off. Problems onloccur when running massive turbo's capable of pushing too much air for the valves to manage (big trucks etc.), so there's no real harm in removing your back box. I've even seen people say it makes very little difference to noise levels, so if it removes restriction and your happy to do it then go for it.

Unless you mean the difference in speed between turbine and compressor side, in which case sorry, ignore the above, but I doubt that would be an issue on a 1.4 or even a 1.9 until you hit big bhp and boost levels.

just taking the back box off won't make much of difference (apart from noise), it's not just the decat and silencers that restrict the flow of the exhaust, the standard diameter of the pipe is just as restrictive. i fitted a straight through side exit on to my scirocco td that was just made out of the standard system and it did very little performance wise, i've made another side exit for my jetta thats 3" from the turbo all the way out the side (running the same kind of 1.6 td) and it's made a massive difference. with the old system i couldn't get more than about 18 psi, with the new one i can max out a 30psi gauge

this is the standard exhaust diamiter for my car


and this is the new one



and to the comment made about more air meaning more power isn't true, if you just wound the boost up to 30psi you wouldn't get any difference other than less smoke and lower EGT's. it's more fuel that improves the performance, more boost allows you to burn more fuel but more boost on it's own will do nothing.

*off to get some scaffold poles* lol I still think i will just remap it to 100bhp, give it a good service and leave everything else standard! Would like a full, turbo back exhaust, but for the money and hassle, i think i will just stick with what i've got.

Thanks anyway though, really good advice

which is actually what i said

but agreed about just back box removal, the cat is a far more restrictive point in the system than the box/silencer, probably followed by pipe diameter, then box.

would a larger diameter give any improvment on stock boost levels though?

oh right my bad, must of got the wrong end of the stick


you wouldn't see an increase in standard boost levels with a bigger pipe because your actuator would still be keeping the boost to standard levels, but if you wanted to wind the boost right up a larger exhaust is essential, trying to get more boost through a standard system is like trying to blow as hard as you can through a strew

perhaps it aint too clear, sorry dude, but what you said ispretty much what i meant anyways...

I meant power gains, not boost level. If boost stays constant at stock level, would an increase in pipe diameter up the power or is a stock pipe wide enough for stock boost? when you upped your diameter you say it made a difference, did you increase boost too or were you still runing stock levels?

my car had already had a lot of tweaking to the fuel pump and was running with the actuator disconnected so i can't answer your question because on mine changing the exhaust changed every thing else as well like the boost levels and being able to burn the extra fuel it was already getting. it did make a massive difference performance wise but this was probably more to do with it working together with every thing else i had done to it before fitting the exhaust.


i guess that if your only looking for small gains then the stock diameter is ok, but if your looking for any thing more than that then you really need to open up the exhaust and let it breath. also while tuning on the stock system you need to keep an eye on you the exhaust gas temps, if these get too high it can damage your engine aparently

all true but didnt realise was 1.4tdi until after i wrote it all lol.

mine should be running big power in summer

is yours a GT or the 100 sport? If the latter, where have you found the 50 extra ponies from? you changed the injectors/turbo too or is it all from an agressive map?

shes the 100 sport lad.

when getting it mapped we noticed it had larger injectors than standard, me nor the previous owner changed them. we think its a factory mistake?

it ran 118bhp before mapped and 151.2bhp after map. although the temp sensor gauge on the dyno was running slightly hot so 140-145bhp is more realistic. 260lbft

the GT-1749v was running 1 bar pressure but now is 1.3 bar pressure. so it will be getting upgraded to hybrid in summer

whats your tdi like?

good old 3 cylinder 1.4 .

Pipercross panel filter, passat side mount intercooler (slightly longer) and a remap. not sure of bhp but she's runnin 256Nm on the torque scale, not bad seen as they're 195 standard.

Lookin at getting hold of some PD130 injectors but they are expensive little things and rarely come up second hand from what i've seen. Also got a boost controller but want to get a gauge in first before I start manually pushing the stock turbo higher. May hold out till I've got more money and trade her in for a GT, but I have a lot of love for the 3 cylinder, think its the underdog factor more than anything...

nice, is there any point in 130 injectors? would they even fit the 1.4? imo i would save and buy a 1.9tdi, so much better and easier to get power out of

mine is 352.82nm or 260lbft

surprises alot of people i will tell you.

far as I know the 1.4 deisel engine is almost identical to the 1.9, its just 1 cylinder less. the 1.9's have a different exhaust manifold (obviously, theres more cylinders) and turbo, but I think the fuel system is the same, including injectors (just one less). I could be wrong though and need to do a bit more reading on the matter.

As for the point, I'll only do it if i can do it cheap, if its gunner cost, I'll save for a GT, more fuel = more power at the end of the day, plus its just something else to tinker with. I've suprised a couple of standard 1.9's as she's running more torque and potentially more bhp than a standard one, also bullied a friends focus titanium, but in his defence he did have more stuff in his car than I did.

My car has just failed the MOT on the back box! ..its pretty crusty. If only it would pass the MOT without one! so.. anyone who's taken theres off fancy selling it to me?!

Remap is the best bet mate.
Wont get more "bang for your buck" for less.

for information on TDI's check out this site. Dedicated to all things TDI

my daily car is a 1.9tdi seat leon. It was the 110bhp model, but now its over 150bhp, due to various tweeks

cheeky snapsB)