Leon 1.9tdi tuning

[jhr1]

Hey guys,

Sincerest apologies if this has been covered before, or if its getting repetitive, im new to this tuning lark, if other threads have covered my topic please just direct to them

Basically I plan on buying a leon cupra tdi at the end of this year, ive already set in motion giving my ibiza back to the dealer in october, and getting a works van to runa round in for a while whilst i save some cash.

My plans besides the obvious from alloys/arbs/suspension are to make it faster, and as far as I can see i have to options

1) a custom remap, intercooler, dv, airfilter, exhaust

or

2) go the whole hog and have a big turbo conversion with all the above plus clutch,turbo,piping,brakes, etc etc

I'm jsut after opinions of which is the best route to take? is a big turbo conversion safe for the engine, does it throw up any reliability issues? and how much does it cost/who does the best big turbo conversions?

All help and info muchos appreciated!

 

[glynnd]

Going the latter route will cost about 3 to 3.5k but well worth it.
Depends on what you can afford to do at each stage.
Certainly a custom remap clutch and hybrid is around 2k depending on spec and supplier of the turbo, it could be more than that.
Glynn

 

[jhr1]

thanks glynn, i really am edging this way, jsut need to find a tuner that will do whole kaboodle for me, and leave no nut un-turned sorta thing

 

[daboy3000]

Can you change the dump valve on the tdi for a better/louder one?

 

[jhr1]

not sure lol, hence why i asked,........my mate had a diesel cupra once and he had a very chattery DV, but it only made noise on down shifting not on up shifting so no idea if it was after market or OEM and only making noise cause of the remap.......I'm not to clued up on the DV diesel side tbh

 

[daboy3000]

Mine makes a great noise when changing up but it can always be louder! I want that tweeting noise you get from the big boys

 

[jhr1]

hmmm ill have to wait and see when i get the car, i guess an open cone induction kit could possibly increase the noise?? as said, not sure how it works on a diesel

 

[johntheboy]

Can you change the dump valve on the tdi for a better/louder one?

I didnt think the diesels had an actual dump valve?? I asked about this before and got told they didnt have one?

 

[devonmikeyboy]

Fact 1: Diesel are not produced with a dump valve.
Fact 2 : Diesel dump valves do not improve bhp/performance or anything on a diesel engine infact if your lucky and buy a very good diesel dump valve you will loose no bhp/performance most are crap sound crap and lower diesel engine performance.

 

[johntheboy]

Fact 1: Diesel are not produced with a dump valve.
Fact 2 : Diesel dump valves do not improve bhp/performance or anything on a diesel engine infact if your lucky and buy a very good diesel dump valve you will loose no bhp/performance most are crap sound crap and lower diesel engine performance.

So if theyre not produced with any where would they be mounted? Any photos avalble on the subject?

 

[flappy]

What engine are you looking at starting with? If the 150, it already had a good intercooler. A map, exhaust and clutch is a good starting point. 312mm conversion for the brakes are also a good idea

 

[Muttley]

Diesel dump valves part 1:

Petrol engines have a throttle mechanism which controls the flow of air between inlet (turbo-compressor) and the engine combustion chamber, so as to keep the air-fuel mixture in the ignitable range while throttling the engine's power output. The mass of air taken in and fuel added must both be carefully controlled.

When you close the throttle on such an engine the compressor is still pushing air into the inlet and it suddenly has nowhere to go. The back pressure will inevitably slow the turbo down, and cause turbo lag when the throttle is opened again. The solution is to provide a pressure-actuated valve, which reacts to a difference in pressure between the two sides of the throttle, opening to dump the excess pressure to the ambient (dump valve) or back into the inlet (recirculating blowoff, which does a much better job by equalising the pressure on both sides of the turbo). Without this, throttles and turbos would have to be much more heavily engineered and throttle response would suffer.

So dump valves are about throttle response at gearchange and other sudden transient events, not about performance in the leadfoot top-speed way of thinking.

The need for a dump valve is a weakness of turbocharged petrol engines, putting another contraption in the inlet side which disturbs the gas flow and is a point of failure. I find it mildly astonishing that anyone should be proud of their car farting on the overrun. But then I have a diesel so I'm probably disqualified from having an opinion.

Diesel engines have no throttle. Power output is controlled by the fuel quantity injected at each stroke. Mass flow around the compressor-combustion chamber-turbo impeller loop is always uniform. This makes diesels much better candidates for forced induction.

A dump valve can only do harm to the performance of a diesel.

Turbo wastegates are not dump valves, they limit the pressure on the impeller (exhaust) side of the turbine to prevent the turbine from overspeeding when the engine's gas flow becomes too high i.e. at high rev's. The higher-performing VAG turbos use variable-geometry inlet vanes and have no wastegate.

There are "dump valves" for TDi's that are activated by the ECU, such as the Forge one. If fitted and adjusted properly they do not affect performance, they just make a noise. So you can fit them anywhere you like, wherever you want the noise to be heard best - say, on the dashboard, or maybe on the roof.

Here endeth the first lesson

 

[devonmikeyboy]

So if theyre not produced with any where would they be mounted? Any photos avalble on the subject?

Go on the Forge website mate and have a look. They have photos and fitting instructions.

 

[jhr1]

wow thanks guy, much appreciated so i can scrap DV off the list haha, not interested overally with the whole wooshy noise, it would of been nice to leave chavs in a wake of dust with high pitched whine, but the dust will do for me then lol

 

[johntheboy]

Diesel engines have no throttle. Power output is controlled by the fuel quantity injected at each stroke. Mass flow around the compressor-combustion chamber-turbo impeller loop is always uniform. This makes diesels much better candidates for forced induction.

A dump valve can only do harm to the performance of a diesel.

Turbo wastegates are not dump valves, they limit the pressure on the impeller (exhaust) side of the turbine to prevent the turbine from overspeeding when the engine's gas flow becomes too high i.e. at high rev's. The higher-performing VAG turbos use variable-geometry inlet vanes and have no wastegate.

Here endeth the first lesson

So... I was under the assumption that diesels still had a throttle body that the pipe leaving the air box went to? Do they not take under the same principle of having to mix fuel and air to run properly as a petrol engine?

Also could a diesel dump valve jobbie do damage to a turbo such as the impellers becomging bent or distorted? Or is there something elce which could do this?

 

[daboy3000]

@Muttley Thanks, great explaination, I'll give that a miss then.

 

[Muttley]

johntheboy wrote

So... I was under the assumption that diesels still had a throttle body that the pipe leaving the air box went to? Do they not take under the same principle of having to mix fuel and air to run properly as a petrol engine?

Oh dear, no.

A moments Google found these two sites among many that describe how the diesel cycle works.

No throttle plate, butterfly valve or piston, nothing obstructing the inlet tract at all, a full charge of air is taken in at every stroke. Fuel is injected into the cylinder at a precise time around the top of the compression stroke, and is ignited by the heat generated by compressing the air in the cylinder (like a bicycle pump gets hot when you're blowing up a tyre, only much more so). That is the defining pricipal of the diesel: fuel and air are mixed at the time of ignition.

The precise amount of fuel injected and the timing of the fuel delivery is the means by which a diesel engine's power output is controlled. This is one of the reasons a diesel is more efficient than a petrol engine (gets more mpg) - most of the time it is burning lean. Nowadays the fuel delivery timing is done by the ECU, before that the diesel distribution pump did it all mechanically.

Also could a diesel dump valve jobbie do damage to a turbo such as the impellers becomging bent or distorted? Or is there something elce which could do this?

It is highly unlikely that anything short of a sledgehammer could distort the turbocharger's impeller vanes. Have a look at this stripdown.

Here is a VAG publication describing the older TDI90 engine, which will give you an idea of most of the bits in the TDI. The 110 has a variable vane turbo rather than a wastegate, and the PD engines get the fuel to the cylinder in a very different way.


You will find a butterfly valve in the inlet tract, next to the EGR valve: however this is the Anti-Shudder Valve and is only closed briefly when the engine is switched off, to cut the air supply and supress the shutdown shudder common to diesels.

 

[johntheboy]

johntheboy wrote

[
It is highly unlikely that anything short of a sledgehammer could distort the turbocharger's impeller vanes. Have a look at this stripdown.



You will find a butterfly valve in the inlet tract, next to the EGR valve: however this is the Anti-Shudder Valve and is only closed briefly when the engine is switched off, to cut the air supply and supress the shutdown shudder common to diesels.

Recently had to have the turbo fixed because the blades in my turbo were bent. This was done before my purchasing of the car and god knows how it was done but luckily it was fixed through waranty.

I was told that after fitting a panel filter I should spray some throttle body cleaner into the throttle body (to remove built up grime) but couldnt remove the pipe to where I would have assumed it would be to have a look. Take it this wouldnt have done any good?

 

[flappy]

I always thought that the blades were brittle and would snap rather than bend?

Two cracking posts Muttley

 

[Muttley]

johntheboy wrote

Recently had to have the turbo fixed because the blades in my turbo were bent. This was done before my purchasing of the car and god knows how it was done but luckily it was fixed through waranty.

Interesting. What evidence did the dealer present to convince you that the blades were bent, and what did they do to fix it?

I would have thought that replacing the turbo would be the only sensible way to fix an issue with impeller or turbine blades, any force strong enough to bend them woud compromise the bearing.

About the only thing I can think of that could be bent on a turbocharger that could be fixed with less than a whole new turbo would be the VNT or wastegate actuator arm. Do you have the job sheet, or anything that tells you what they did?

I was told that after fitting a panel filter I should spray some throttle body cleaner into the throttle body (to remove built up grime) but couldnt remove the pipe to where I would have assumed it would be to have a look. Take it this wouldnt have done any good?

Whoever told you this was applying petrol-engine recommendations to a diesel. Is this the same people who told you they'd fixed a bent turbo?

Put it this way, if they're still around, get them to point out to you where the throttle body is on your diesel engine. Take a picture then post it here - I could use a laugh.