benefits of a front mounted IC on a TDi

[jbh]

right as some folk will know im in the middle of an engine change on a seat Alhambra thing for the misses. now im breaking our old Sharan ( vw version of the Alhambra ) so these have a front mounted inter cooler.. so this got me thinking.. could I get it to fit the A4.. I reckon I could with a few brackets and some pipe work. so would I see any benefits from doing this?

heres a picture of a sharan inter cooler ( stole the pic from eBay )

 

[aragorn]

if your going to do it, then do it properly and fit a big one.

The one in the photo doesnt look any bigger in terms of area than the stock a4 part, so your unlikely to see any gains.

Mate of mine fitted a big ebay core to his Bora TDI and reconned it make quite a noticeable difference, though his stock cooler was a bit ruined.

 

[jbh]

if your going to do it, then do it properly and fit a big one.

The one in the photo doesnt look any bigger in terms of area than the stock a4 part, so your unlikely to see any gains.

Mate of mine fitted a big ebay core to his Bora TDI and reconned it make quite a noticeable difference, though his stock cooler was a bit ruined.

I have thought about getting a bigger one to fit. my thoughts with this was it's there already and with it being a front mounted rather than the side mount would it make a difference.

 

[aragorn]

not really, the advantage comes from the bigger core, rather than the position.

a well ducted side mount will work better than a badly ducted front mount of the same size.

 

[adamss24]

A big inter-cooler will add more lag as the turbo has to work harder in order to fill up the larger space displaced by the core. Only upgrade in conjunction with a hybrid or larger turbocharger. The factory inter-cooler is pretty big and efficient, it's just the position it's at is little restrictive. Add a s4 inner wheel arch (has cut slants) to aid venting trough and also make sure the factory cooling duct is in place. I had 1.9 tdi with bv43 and more mods and they were fine in 40 C heat...

 

[aragorn]

What were your IAT's though?

"fine" doesn't actually mean "good"

The stock cooler is pretty ****e, and heatsoaks pretty quickly even with a stock motor when driving hard.


The "lag" thing is a myth imo, you simply wont notice the difference. The static volume of air in the cooler is essentially negligible compared with what the engine is injesting at full boost.

 

[adamss24]

Kev, no disrespect but i tune cars for a few years, last passat i've been in had 3" pipes and front mounted inter-cooler and that was laggy as hell ! The car had a pd130 engine running a 6 speed v6 tdi gearbox, a GTB2056vl turbocharger and a very aggressive cstom map ! It was laggy but was going ok with 250Bhp on boost !
Petrol engines have a wastegated turbochargers and double the rev counter, diesel engines have their torque low down the rev range and tails off sharpish !

 

[s3dave]

Carnt you just do away with an IC altogether and run a **** load of methanol ..zero lag? or would it blow up a soot chucker?

 

[aragorn]

Kev, no disrespect but i tune cars for a few years, last passat i've been in had 3" pipes and front mounted inter-cooler and that was laggy as hell ! The car had a pd130 engine running a 6 speed v6 tdi gearbox, a GTB2056vl turbocharger and a very aggressive cstom map ! It was laggy but was going ok with 250Bhp on boost !
Petrol engines have a wastegated turbochargers and double the rev counter, diesel engines have their torque low down the rev range and tails off sharpish !

Ok, but its got a huge turbo nailed on, so ofcourse its going to be laggy... Thats not caused by the intercooler. Its caused by the giant turbo. Thats like fitting a GT30 and a big intercooler to a 1.8T and moaning the intercooler has made the engine laggy...

The turbocharger doesnt care about engine RPM's. It cares about flow and pressure. A diesel uses MORE air and HIGHER pressures than a turbo petrol for the same power output, meaning the turbos working harder and generating more heat. The principles dont magically change because its running on derv rather than petrol.

Trying to suggest an intercooler upgrade is a waste of time is nonsense. Plenty folk have done it, and i've not once heard someone complain that they've fitted an FMIC and their car is now an awful lagmonster. Typically the result is gains all round and a delighted owner.

 

[adamss24]

Nope, the same car with the stock gt1749va turbo was still the same, it took a full 3 sec of mashing the throttle to get the turbo on boost, i thought the car has some issues at first but that's how it was ! The GTB2056vl is only marginally larger compared to the gt1749va and it has a better flowing VNT mechanism, in theory it works very well on 1.9 and 2.0 Tdi PD or CR engines !

I did not state that a FMIC is no good, i just said that it's not necessary with the OP level of tune and without supporting mods it will make zilch difference ! I would rather invest the money in better brakes, they will do the OP better !

 

[aragorn]

Well something was wrong then, because my mate has a fairly big (560x230x60 core) ebay intercooler, with 2.5" pipework and 1.8T pancake on his PD130, and it drives better than it ever has. Boost is instantaneous, even at very low rpm's it just goes.

 

[jbh]

I did not state that a FMIC is no good, i just said that it's not necessary with the OP level of tune and without supporting mods it will make zilch difference ! I would rather invest the money in better brakes, they will do the OP better !

Hi Chris bigger brakes are in the pipeline once the wifes car is on the road and im happy with it.

this thread was started just out of curiosity as I have this FMIC sitting so wondered if it would be better than the original side mount. future plans do include the PD130 manifold, gt1749va turbo and bigger injectors. as you know my cars already had a rem,ap so it goes well considering shes running on standard parts.

 

[aragorn]

Why a 1749 and not a BV43?

 

[@udi A3]

I did have a large sidemount fitted on my remapped to 170 ish bhp 1.9 tdi. Makes no difference to the stock intercooler. I took it off again! I have s3 vents in the arch liner, and foglights blocking the airflow.

Personally id like a chargecooler, something like that on the pug t16, maybe either of you could express your opinion on charge cooler over intercooler on a low tune level car ?

TY!

 

[aragorn]

chargecooler is fine, but you still need to cool the water and your just adding additional efficiency losses by having two seperate heat transfers. You also need a big radiator for the water to ensure you dont get heatsoak.

IMO chargecoolers are better suited to where packaging issues mean you cant fit a normal intercooler. They cost more and are more complicated for little to no gains over a correctly sized intercooler.

Did you compare intake temps before deeming your large sidemount to "make no difference"?

The big error i've seen with upgraded sidemounts is folk dont sort the shrouding, which is critical to side mounted intercoolers working properly. The stock shroud either doesnt fit and gets left off, or fits badly and either doesnt expose the whole core, or isnt properly sealed to the core, so air just ****** round it. I've seen logs of upgraded side mounts on an A3 actually resulting in much higher intake temperatures, due to no shroud being fitted!

 

[jbh]

Why a 1749 and not a BV43?

I have a good gt1749va sitting in my mates garage that hasn't cost me anything.
wouldn't the bv43 give me loads of turbo lag?

I will be wanting to keep the car usable as a daily

 

[aragorn]

I wouldnt think the 43 would give you loads of lag, no.

Its slightly bigger again than the PD130 turbo. Its just that the PD130 unit isnt really all that much bigger than the 110 part (your existing turbo is already a GT1749V, the VA is just a tiny bit bigger), if your spending the money, the bigger jump to the 43 seems more worthwhile. Ofcourse if the PD130 unit is free, that means its probably worthwhile, so long as the power ceiling for that turbo will satisfy your demands!

1749VA will see about 170hp maybe a touch more if you really push it, whereas the BV43 will happily flow 200.

 

[adamss24]

On contrary, the bv43 is laggy on the 1.9Tdi AFN engine, my mate has one of my old b5 AFN quattro avant with 11mm pump, 0.216 nozzles, BV43, pd intake/egr delete and chipped ECU. Even with the actuator shorter it was still laggier than the gt1749va he replaced it with ! It's a great drive car and i can assure you that bv43 is laggier than the VA turbo even on PD engines, they start boosting after 2000 rpm with full boost coming in at 3000rpm's ! One thing to watch James is for clutch slip, the va turbo is very snappy and will slip the clutch with larger nozzles, avoid lugging the engine (high gear/low speed situations) and drop a few cogs if necessary !
Only way to properly drive the bv43 on AFN engine is with a ported head and race nozzles, 0.260 or bigger as a minimum !

 

[aragorn]

MRC's 210hp BV43 shows more power and more torque right across the entire rev range compared with the stock VE110 turbo, except for sub 1600rpm. It also hits its torque plateau at 2000rpm.

So while it might be marginally laggier, i suspect that in real terms it'll be fine. From 2000rpm to 3800rpm you've got over 400nm. Its pretty much the perfect turbo for a streetable 1.9tdi IMO.

MRC's car also didnt have a ported head or any internal modifications.

The dyno plot for your viewing pleasure:

 

[adamss24]

Doug's a4 had Xflo 0.275 nozzles, a rs4 side mounted intercooler and a 10mm pump with a 11mm pump head. The cam plate from the 10mm pump is more aggressive than the 11mm pump and it only deliver's 5-10% less fuel than a true 11mm pump. Also a dyno does not represint how a car will drive on the road, i am sure what i said above is true, you need big nozzles and 11mm pump to drive the bv43 properly on a VE head without surging !
I had a similar spec a4 FWD tdi, AHH 90 Bhp engine with VNT turbo, real 11mm pump, race nozzles 0.260, ported head, twin valve spring setup, thicker head gasket, stronger pd150 head bolts,forged rods and stock Mahle pistons. With the va turbocharger it broke the flywheel in 2 pieces, with the bv43 it was a bit more controllable and the clutch did not slip as the power came in later. The car wasn't even mapped, i was still running the stock 90Bhp tune !

 

[aragorn]

If the car wasnt mapped, the VNT mapping is going to be completely hopeless, so isnt representative in any way of how the turbo should be performing. VNT mapping is CRUCIAL in getting the best lag-free performance from a non-standard turbo. I've seen hybrids performing hopelessly with huge lag because the tuner hasnt properly dialled in the VNT map.

I think the MRC car was on 0.260's, upgraded intercooler and 11mm pump head like you say. However the engine is internally stock. As i said before, its up there for being a perfect bolt-on upgrade for a daily driven TDI. You can go silly with forged internals etc, but it just snowballs into a rediculous amount of money, and once you've spent all that its a waste just to fit a BV43, when you should be installing a 2260 and going for BIG numbers.

Sticking to a smallish turbo and external only mods keeps the cost down, and WILL produce good results. Sure it might be marginally more laggy than the stock turbo, but you've got double the power and a massive spread of torque, so a bit of lag below 2k really doesnt matter.

Not sure why you think the engine will magically "surge" if you havent got the big nozzles. If its mapped properly it'll work just fine, it just wont make 210+ hp on the standard parts.


If it were my engine, i'd start by sorting out the turbo, intercooler and exhaust getting all the ground work in place. Then slot in the 11mm pump head, 0.260 nozzles and get it remapped by someone who actually knows what they're doing.

 

[adamss24]

Actually on my car with the mods above the turbo did not surge at all, the VNT wasn't adjusted at all- it was a brand new turbo after all- and was smoke free ! As you said the bv43 was just a stop gap as i have already modded a GTB2260vk to fit on a manifold with a welded flange. Crashed the car(hit a lamppost) and the car sits for nearly 2 years- been looking for a tidy quattro sport to throw the engine in ever since !

If the turbo has a factory adjusted VNT and stop screw you don't need to adjust the N75 map, it works just fine. Of course you modify SOI, advance fueling and ask for boost higher up the revs (adjust boost map and driver's wish map, smoke map,etc.) so the car does not go into limp mode. Only issue with fitting larger nozzles is re-calculating the pump's voltage map. The AHH has the pump from factory so the maps are there very similar to the ALH but very different from the AFN pump !

As you said, forging an engine is a bit pointless if you're not chasing big numbers but at the time i bought the engine with bent rods-following a turbo failure- so i had no choice but to either fit used good rods or go aftermarket ! Whilst an engine is in pieces i always port the heads and upgrade the valve springs- this was no exception !

 

[aragorn]

ofcourse you need to adjust the VNT map, the amount of N75 duty cycle depends entirely on the turbos response curve, a big laggy turbo will need the vanes held shut much longer to get it spooled up and will require completely different vane openings thru the rev range to the tiny stock turbo. The ECU will compensate for a **** map, but this is nowhere near as good as the map being correct in the first place.

The ECU needs to know that for a given RPM and a given load request, it needs x% N75 duty cycle. If for example it thinks it needs 70% but the turbo only needs 40% to meet the demand, then you end up with an overshoot as the ECU will jump to 70% realise its overshot then back off. This creates awful boost control on transitions, both over and underboost depending on the various factors.


You need to get the 2260 on the road!

 

[adamss24]

The 2260 is too big for a 1.9 Tdi, it will surge low down due to larger trim on the compressor, however i just bought a gtb2056vl which i might use at some point assuming the exhaust housing is interchangeable with the gtb2260vk ! I have already flanges/manifold and oil feed/drains + monster clutch and single mass flywheel, 6 speed 01E gearbox conversion and much, much more ! However i am getting lazy and i have just bought a very, very tidy a4 v6 tdi saloon quattro which runs and looks awesome ! I might play with that for a bit...throw a BDG cam roller engine, a 3 plunger pump with AKE head and chip the ECU for a truly awesome drive ! If it oes as nice as my old s reg a4 quattro then i will be happy ! I love the b5 chassis so much- it really handles well compared with later cars and there's no mikey mouse electric aids to hinder your driving skills !