Ultimate MK4 TDI build for MPG

[PremierSprinter]

I would like to share the build for my MK4 Jetta. It started life as a 24v VR6 6spd car which somebody tore apart to use as a donor (fortunately for me). I purchased it to bring back my previous Jetta TDI 5spd of the same body-style and color which was clipped in the rear by an SUV driver.

Donor Jetta and the new one:


The plan for this Jetta is to pack it with OEM+ features while also making it a highway MPG champion. This is the plan:

Engine/efficiency mods
VNt2256 turbo w/ custom tube manifold for lower EGTs
EGR/cooler delete
3" downpipe, coiled with coolant lines for fast warm-up
Custom intake manifold with an air-water intercooler plate inside for short charge pipes
Repurposed throttle body or exhaust cut-out as an emergency run-away valve
Mild head porting
ARP head studs
Decking the head and using the thinnest possible head gasket for a minimal quench height
Sprinter 502 nozzles
Tune - (undecided and may do it myself)
Delete engine-driven PS pump and install MK5 electric rack (never seen it done but confident that I can make it work)
(maybe) Smaller electric A/C compressor
Chrome roof wrap to deflect the sun's heat
Long 5th gear

Aero mods
Mirror deletes
Grill blocks
Front lip
Vortex generators
Wheels spats
(maybe)Rear diffuser
(maybe)Bonneville-style spoiler
LRR tires

Just-because mods
Nissan GTR seats
MK5 GTI speakers and amp
In-dash TV and back-up camera
Climatronic swap
Class III trailer hitch
Satin pearl white vehicle wrap

So far I have pulled the motor from the old car and put it aside to pull the motor from the new car:






MK5 electric rack... I'm not sure how well this is going to work yet but I have one extra MK4 rack and subframe which I can hack up to make it work if I need to. I also have to complete car harness. I am already wiring in the BCM in order to have an interior CAN capable of turning the amp on. I need to get some MK5 wiring diagram to see what makes this tick. It has a power and ground wire as well as two orange wires, one with a black stripe. I know that there is a steering angle sensor in the column so i will probably use the MK5 column. I'm confident that I can get it working and it should be good for reducing parasitic losses on the highway with no power steering pump.


This one is self-explanatory, the VNT2256 next to the VNT15. This one was electronically actuated so i will have to make a bracket for the new vacuum actuator.


Lastly, GTR seats. These seats have the electric motors and heaters in them but the lower motors have been gutted. I'm going to find a set of electric MK4 seats and use the forward-backward/up-down motors from that and control them with the GTR switches, then wire the heaters to the OEM VW switches. There will be some upholstery work in the car. I would like to stay a light color as to not retain heat so I may just try to match some pieces in the car to this color.



I'll post updates as I get more work done.

[jedi_sol]

I'm always jealous of people with fancy garages and fancy tools

I'd skip the vortex generators and bonneville style spoiler.

If you a REALLY going for the Highway MPG beast....you should consider

1) building a kaamback (or boattail)
2) smooth underbody tray

[Vman455]

Subscribed.

[PremierSprinter]

Originally Posted by jedi_sol

I'm always jealous of people with fancy garages and fancy tools

I'd skip the vortex generators and bonneville style spoiler.

If you a REALLY going for the Highway MPG beast....you should consider

1) building a kaamback (or boattail)
2) smooth underbody tray

Thanks, it's my commercial property. It's great to have a lot of space and a lift for projects like this. After years of working at dealers for germans brands, you wind up collecting a lot of tools. My current business has a lot of fabrication involved so I have the capabilities to build just about anything that I want in-house.

I definitely don't think that I would be willing to drive a car with a boat tail. I plan on putting my company logos and everything on it so I want it to look good. The bonneville-style spoiler was predominantly chosen to keep the function of the trunk. Do you think that there is an advantage to running this type of spoiler over stock? I definitely do plan on making smooth under-body panels. There are quite a few things which I couldn't think of off of the top of my head.

[RunningStrong]

Which TDi engine will this have? I've the 1.9 PD but unsure if you guys ever got this.

Also, have you considered an oil heater? There's some pretty nifty ones you can stick on the oil sump.

[Eddie25]

imagine if you could have the 6 speed box on that tdi motor! awesome cars those!

[PremierSprinter]

Originally Posted by RunningStrong

Which TDi engine will this have? I've the 1.9 PD but unsure if you guys ever got this.

Also, have you considered an oil heater? There's some pretty nifty ones you can stick on the oil sump.

It's an ALH motor. I didn't plan on putting an oil heater on it. It's something I'll have to look in to. I was thinking that I might do a traditional block heater but my cars do stay inside at night throughout the winter so I am not sure that it would be worth it.

Originally Posted by Eddie25

imagine if you could have the 6 speed box on that tdi motor! awesome cars those!

It's an option that I am debating. I have two 6spd transmissions at the shop right now but the gears are a little too short for me. I have e-mailed some distributors in the UK to attempt to get a transmission with better ratios but there is no guarantee. The longer gears for the 5spd are actually also longer than 6th+FD in the 6spd TDI transmissions. The disadvantage is that there is a hefty jump to fifth from fourth which isn't great for driving around town, especially while towing. If I can get a trans for a good price, I will probably wind up doing it.

[deejaaa]

"Delete engine-driven PS pump and install MK5 electric rack (never seen it done but confident that I can make it work)"
I will subscribe because of this. I can't see the pics on this comp so will look at home.

you can add a 6th to the 5 speed. go to tdiclub.com in the MK4 section and there are a lot of threads on it.

[cRiPpLe_rOoStEr]

That's an interesting project. Regarding engine pre-heating, even if your cars stay inside at night during winter, some electric coolant heater and a heating pad at the oil sump can actually be very helpful regarding efficiency since it would lead the engine to its optimum temperature sooner. You might even take a look at wrapping the sump externally with some insulation. BTW do you remember some big rig engines such as the Detroit Diesel Series 60 had composite sumps and some Caterpillar engines even have composite valve covers?

[PremierSprinter]

Originally Posted by deejaaa

"Delete engine-driven PS pump and install MK5 electric rack (never seen it done but confident that I can make it work)"
I will subscribe because of this. I can't see the pics on this comp so will look at home.

you can add a 6th to the 5 speed. go to tdiclub.com in the MK4 section and there are a lot of threads on it.

Glad to have you on board. I know that I can get the rack to fitwork at least by swapping the aluminum MK5 subframe to the MK4 and using Mk4 balljoints on the MK5 control arms. I would likely have to change the mounts out which I could do by cutting them out of the MK5 in the front and plating/drilling the rear, just like I would for putting a MK3 VR6 subframe into a MK1. If possible, I'd like it to be more comprehensive though, so that others can follow. I'm more concerned with the electrical aspect than I am the mechanical, as a don't have a clear path of what the system needs to function. I assume that it needs the steering angle sensor, which means I will probably wind up mixing the two columns together as I want to keep the MK4 splines and clock-spring. Beyond that, it could wind up being a pain. I have the MK5 ESP module, BCM, etc... if need be. I think that I will be wiring in the BCM anyway to wake up the MK5 amplifier as I don't know that the MK4 CAN can do it.

The 5spd to 6spd conversion have been around a long time but they were pretty expensive if I recall correctly. I know that this is sort of one of those "pay to play" kind of hobbies, but the tallest 5th gear is actually taller than the 6spd swap gears. Using a real 6spd also has the advantage of moving to the 240mm clutch which is more well-suited for a modified TDI. I still have to weigh out my options but at this point, I am leaning towards to tall 5th if I can get my hands on a 6spd cheap enough.



Today was a great day at my local "pick and pull". I scored a complete climatronic set-up (even the dash-top and front bumper sensors), plus an auto-dimming mirror w/ rain sensor and then a pair of full electric memory seats, all for $191. I will have to replace the front windshield to use this mirror, which I intended to do anyway. The seats also had lousy leather. It was perfect for me because I only needed the frames, motors and control unit as I am chopping them and welding together full-electric, memory, heated Nissan GTR seats (for the eco-baller in us all).

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