BRM Stock FMIC - Too Much Pressure Drop for Big Turbo?

Alright, I have been waiting to post my build thread wanting to work out some kinks first. I always enjoy seeing the "this is what I did" threads so much more than the "this is what I want to do" threads.

I am now up against an issue I didn't see coming and need to find a robust solution. From the start of the build I have been working with Mike at TD Tuning (very skilled AND patient BTW) and struggling to get the boost response and clean power my hardware should be capable of. The car has steadily improved but still just not quite right. Mike is seeing strange boost effects in the logs but we have not been able yet to figure out the hardware cause.

Just got a revised tune with some N75 changes and started blowing the IC tube off the turbo. I chalked it up to the not quite right fit on the silicone connector forced by using the stock plastic IC pipe. So I researched and found a much better fitting coupler. I installed it today, excellent fit this time, and blew it off again before I could get a log!

Some details on the build that might pertain to this issue:

• Freshened up engine, rings and head rebuild
• Colt stage II BEW cam, mildly ported head
• GTB2056VK turbo with BRM actuator on Driver's Fire manifold
• Tune is targeting only 25 PSI for now
• Full 3" exhaust with Moroso spiral core race muffler only, high flow cat will go in place of muffler once car is dialed in better
• R783 nozzles on ARL bodies
• Stock FMIC and piping
• MAP sensor is mounted in stock location, outlet of IC
• Boost gauge sensor in intake manifold

Here is what I am thinking might be going on: too much pressure drop across the IC. Since the MAP sensor is post IC it could be really confusing the ECU if there is a significant flow restriction between the sensor and turbo trying to satisfy tune requests. And I am not seeing the restriction because of where the boost gauge sensor is.

This might explain my laggy looking group 11 log and the major overshoot and struggle to correct actual boost? When smoke does clear, it comes back at high RPM in spite of higher boost.

I am hoping some of the euro based builders can chime in about the flow characteristics of the thin OEM FMIC on these cars. Problem for them? what to do about it? Whitbread recommended I look over at Vortex to see what the 400-500HP 2.0T guys are doing for an IC. There is really next to no room for a bigger IC on the MkV. Maybe someone makes a bolt on solution?

For now I am going back to a previous tune revision, will baby the car and leave Mike alone about the tune until I figure out what is going on here. I want to put a pressure gauge pre-IC but it will be difficult with the plastic IC pipe and IC caps. I'll have to think on that one.

Expert thoughts on either the idea of too high pressure drop, or where to find a better flowing FMIC kit?

Thanks in advance!

Quick googling turned this up http://www.urotuning.com/shop/oem-euro-s3-intercooler-kit-mk5-20t-p-729.html

http://www.amazon.com/Godspeed-Jetta-A3-FSI-Intercooler/dp/B0056ILA6E

Did a little research and there are a few IC alternatives from the 2.0T cars.

Budget route would be to use this unit from an OEM S3: http://www.ecstuning.com/Volkswagen-Jetta_V--2.0T/Engine/Intercooler/ES9949/

EuroJet offers their upgrade version of the same design: http://www.ecstuning.com/Volkswagen-Jetta_V--2.0T/Engine/Intercooler/ES2083315/

This unit from Forge is the most intriguing to me as it would retain my stock IC and add one as big as many of the MkIV guys are using: http://www.forgemotorsport.com/content.asp?inc=product&cat=0013&product=FMINTMK5

One thing I have noticed is that the 2.0T IC has outlets at the bottom on both sides, while the TDI is low on the drivers side but high on the passenger side. Needless to say, any of these are going to require some custom pipe work. The Forge unit inlet pipe looks like it might work as-is with an adapter for the funky OEM connection. Outlet will have to be all new.

On the bright side, with an uprated IC, the car will basically be ready for a 2260 if I decide to build an engine that could live with it.

Hey Matt, was checking out the links you posted and looked closer at Godspeed. Turns out they have a kit very similar to the Forge one, only le$$: http://www.godspeedproject.com/store/index.php?main_page=product_info&cPath=7&products_id=490

So, if I decide to co with one of these "twin cooler" setups, do I move the MAP sensor from the OEM IC outlet? Will it matter?

Will also have to find a really good aluminum welder in Louisville for the IC piping. Matt and the welder David at Driver's Fire uses both set the bar very high. Now it is "stack o' dimes" quality or nothing!

I only have had a brief interaction with a MK5 TDI, but isn't the outlet of the intercooler near the top instead of the bottom like those show?

ETA - it also appears that the turbo outlet is different too?

How would keeping the stock FMIC plus adding another one reduce pressure drop? It will help cool but your psi drop is going to be about twice as much.

Can you tap a temporary psi gauge on the inlet side of the I/C?

JFettig said:

I only have had a brief interaction with a MK5 TDI, but isn't the outlet of the intercooler near the top instead of the bottom like those show?

ETA - it also appears that the turbo outlet is different too?

Click to expand...

Yessir:

A5INKY said:

...One thing I have noticed is that the 2.0T IC has outlets at the bottom on both sides, while the TDI is low on the drivers side but high on the passenger side. Needless to say, any of these are going to require some custom pipe work...

Click to expand...

A5INKY said:

Yessir:

Click to expand...

sorry, I tend to glaze over the reading and look at the pics while I'm at work

O.C.TDI said:

How would keeping the stock FMIC plus adding another one reduce pressure drop? It will help cool but your psi drop is going to be about twice as much.

Can you tap a temporary psi gauge on the inlet side of the I/C?

Click to expand...

I'm no TDIMeister, but it seems to me that if the IC core is an actual restriction resulting in a pressure drop, providing a path around it that also results in additional cooling should help correct any pressure differential. If 'Meister catches this thread, hopefully he will add his technical 2 cents.

I thought about drilling and tapping and NPT port into the stock IC pipe on that side, just worried that if I need to continue to use that pipe, it might be hard to keep a plug in it under pressure later. I am open to ideas though. Another way to tap in?

Ha Ha! Just found this kit: http://cgi.ebay.com/ebaymotors/VW-G...r_Truck_Parts_Accessories&hash=item4cf814020e

Sure looks alot like the seemingly identical Forge and Godspeed kits, but straight from China! Hmmm - knockoff, or the actual original that got stenciled with a brand name and price more than doubled??

I hate to buy Chineseium parts, but is it possible to avoid anymore?

For a Mk5 / A5 you need to use an S3 intercooler, direct bolt on. Go to ECS for decent pricing. Dont buy the pipes shown on Matt's link as they will end up in the spares bin as your stock ones will work if you chop the clip connectors off!!

We do a hard pipe kit for the BKD but that wont help your custom setup!

What is the boost just before the connections are blown out?

I would suggest that there is big boost spike that the stock connections are unable to handle.

Also check the boost with mechanical gauge. If you have strange boost issues the reason may be bad MAP...

A5INKY said:

Ha Ha! Just found this kit: http://cgi.ebay.com/ebaymotors/VW-G...r_Truck_Parts_Accessories&hash=item4cf814020e

Sure looks alot like the seemingly identical Forge and Godspeed kits, but straight from China! Hmmm - knockoff, or the actual original that got stenciled with a brand name and price more than doubled??

I hate to buy Chineseium parts, but is it possible to avoid anymore?

Click to expand...

I emailed Forge about this, turns out they designed this system about 5 years ago and the others are the knock-offs. I appreciate the fact that R&D costs money and that Forge is more likely than a Chinese factory to be paying their people a living wage. If I choose to go with a "twin-cooler" system, I will buy the Forge one on principle.

ryanp said:

For a Mk5 / A5 you need to use an S3 intercooler, direct bolt on. Go to ECS for decent pricing. Dont buy the pipes shown on Matt's link as they will end up in the spares bin as your stock ones will work if you chop the clip connectors off!!

We do a hard pipe kit for the BKD but that wont help your custom setup!

Click to expand...

Thanks for sharing that Ryan. I am actually leaning toward this type of solution, if not just a conventional style like the BHS or Neuspeed. I was looking at it last night and there is very little room for the cold side pipe to reach the bottom outlet on the S3 style intercoolers. Easiest might be the run the pipe low like some of the MkIVs with FMIC do. Or if I go with something like the Eurojet or APR version of the S# design, I could just cut the cold side end-tank off, turn it upside down and reverse the outlet to match the TDI version. That might actually be easiest (and cleanest) in the long run.

The BKD intercooler outlet is high or low? What motivated you to upgrade them to the S3 IC, IAT reduction or pressure drop reduction? If pressure drop, have you measured the stock BKD IC? Has the upgrade yielded good results?

brum said:

What is the boost just before the connections are blown out?

I would suggest that there is big boost spike that the stock connections are unable to handle.

Also check the boost with mechanical gauge. If you have strange boost issues the reason may be bad MAP...

Click to expand...

I have finally gotten the VNT actuator adjusted just right, been a bit of a learning curve on that one. With that I am getting better logs for the tuner to work with. Matter of fact, Mike just emailed me another file to improve boost control, have not loaded it yet though.

To answer your question, I have an electronic boost gauge that does not rely on the MAP sensor but has it's own sensor in the intake manifold. The tune I was using was spiking to 30 PSI before settling down. However, if there is a significant restriction through that IC, the hot side pipes could have been seeing even higher pressures. I know many of the 2260 guys are running boost in the mid to high 35 PSI range and are able to keep their pipes on.

Since posting this up, I reconnected the coupler that blew off. <fingers crossed> It has stayed put so far today with about 50 miles of driving including running a log for Mike. Looking forward to the tune update and (hopefully) better boost control.

That said, with the turbo adjusted and the tune as close as it is to right, the car is an animal, no more lag than the stock turbo, very very little smoke, and she really rips down the road.

I am feeling good about us being close on this one. The last log had quite a bit of overboost since the actuator was shortened, but it looks controllable and that last revision will likely help quite a bit. I wouldn't be surprised if the stock intercooler may be somewhat restrictive though. Even with a bar and plate FMIC on my car it had a coupler that was always trying to push out from under the (t-bolt) clamp. It was on the hot side as well. So, seemingly the higher pressure in front of the intercooler was a contributing factor.

Sometimes it just takes a lot of troubleshooting to get these one-off setups right.