Mods you're wasting money on...

[EricsVdub]

Probably never gets cold enough in AZ, from outside the car SAI makes some interesting sounds below freezing

Hmm, Jake are you referring to the two days a year it might get colder in Charlotte than Phoenix? Now if you were talking about humidity...

 

[Nineeightyone]

I stand by the list, the intended use here isn’t “don’t ever buy this stuff” but rather what you shouldn’t bother with until the most important mods are done:

-Tune/Jb4

-Motor mounts (or dog bone insert at minimum)

-Tires

-RSB

-Intercooler

-Downpipe

I think the mods listed definitely are the most impactful, and I think the additional clarity of 'Not saying don't buy anything on this list, just understand they're not as impactful as marketing might like you to believe' is a good point.

The recommended mods are definitely going to be a significant improvement in bang-for-your buck. I also remember a time when springing for a $40 K&N filter for my mk4 was a big purchase -- I think as long as folks are honest with themselves about the results they're after when making modifications, that's what's important. GTI Jake's post history demonstrates a clear level of knowledge, and I don't think this thread is intended to be malicious, just informative.

 

[JerseyDrew77]

I have seen a few posts from members not just new to the GTI, but to car modding in general, that have asked this type of question. It should go without saying that most us on the forum aren't rational about cars, so this probably doesn't apply to us. We're going to change things on our cars just because we have the desire to, not because it necessarily makes any sense, LOL. A couple of things to remember though, some peoples' initial mods are going to be guided by budget, tool availability, and mechanical knowledge. It's been a few decades, but I recall not so fondly diving headfirst into suspension mods as a teenager with only standard household tools and no garage to perform the work. In my humble experience, an adjustable wrench should NEVER be used on a car, and NEVER get under a car without jack stands!

I've been around the VW scene for decades now and have been modifying them since day 1. I've always had an end goal in mind and purchased parts that would properly get me there. I did not buy parts just to buy because I wanted to. No, I only bought the parts that were needed to get me to my end goal and if I didn't have the money to buy those parts, I would save up. GTI Jake's list is a reference guide and that's it. He's not telling anyone this is what you should or shouldn't buy.

 

[IanCH]

I stand by the list, the intended use here isn’t “don’t ever buy this stuff” but rather what you shouldn’t bother with until the most important mods are done:

-Tune/Jb4

-Motor mounts (or dog bone insert at minimum)

-Tires

-RSB

-Intercooler

-Downpipe

But your reasoning is not correct here at all (from a fluid dynamics perspective)

The bolded parts are just flat out wrong.

2. Turbo inlet pipe- That little 90* bend at the inlet of the turbo connecting it to your intake, is it a restriction? Well, no. It's not.

1. A bend in pipe is naturally very restrictive compared to straight piping, and for it to not be restrictive you would need to have a larger diameter in the bend compared to a straight pipe of a smaller diameter. Smoothness of the bend also greatly affects flow characteristics, much more than one might think actually.

The inside diameter of the turbo compressor housing isn't getting any bigger just because you slightly increased the piping just before it.

2. The airflow coming into the turbo is being forced by the turbo, if it was natural unpressurized airflow then sure your point would be valid but it isn't. The thing we are concerned with here is pressure drop across the section.

You could do dyno pulls with an open turbo, no inlet pipe or intake at all and the results would be nearly identical.

3. You would see a very significant difference doing dyno pulls with an "open turbo" (quotes because you need to make sure its getting fresh outside air)

The turbo is not restricted by the stock inlet pipe.

4. Yeah, it is. That stock pipe is TINY because the plastic construction means really thick walls and a huge reduction in cross sectional area that is actually much smaller than the turbo inlet.

 

[EricsVdub]

Pictures are nice, but dyno results would be better. I'd love to see cost/HP or ft/lbs for a TIP versus stage 1 tune.

 

[IanCH]

To further prove my point, The inlet - at the turbo housing - is increased by 26% in area. this doesnt even consider the effect of the greater sized pipe and smoother bend beyond the turbo housing.

 

[IanCH]

Pictures are nice, but dyno results would be better. I'd love to see cost/HP or ft/lbs for a TIP versus stage 1 tune.

You can clearly see in the picture that the stock plastic elbow is by far the smallest part of the intake piping, meaning that it is the absolute most restrictive.

What I'm saying is that if you only did the MOST effective mods for this cars intake, the filter and this elbow are the absolute biggest ones, and very cost effective at sub $200

 

[krs]

Pictures are nice, but dyno results would be better. I'd love to see cost/HP or ft/lbs for a TIP versus stage 1 tune.

I'm not an engineer, so I can't geek out on numbers. I do understand hydraulics, and air is similar to fluid flow, so some of the concepts I can understand on a limited basis. But really the way I look at it, is something like an inlet pipe, or intake tube, as a single component may not give you mad gains on a dyno, or really do nothing at all. But collectively with other more efficient components will provide the benefit as they will not be the restrictive piece, or they will be working together.

So yeah buying the inlet pipe as your first mod, not necessarily be a waste of money, maybe just spent money at the less efficient time in the bigger scheme of things.

At least that's what I'm happy telling myself.

 

[FrankieThissen]

But your reasoning is not correct here at all (from a fluid dynamics perspective)

The bolded parts are just flat out wrong.

1. A bend in pipe is naturally very restrictive compared to straight piping, and for it to not be restrictive you would need to have a larger diameter in the bend compared to a straight pipe of a smaller diameter. Smoothness of the bend also greatly affects flow characteristics, much more than one might think actually.

2. The airflow coming into the turbo is being forced by the turbo, if it was natural unpressurized airflow then sure your point would be valid but it isn't. The thing we are concerned with here is pressure drop across the section.

3. You would see a very significant difference doing dyno pulls with an "open turbo" (quotes because you need to make sure its getting fresh outside air)

4. Yeah, it is. That stock pipe is TINY because the plastic construction means really thick walls and a huge reduction in cross sectional area that is actually much smaller than the turbo inlet.
View attachment 200767

View attachment 200768

Some more fluids dynamics observations;

The OEM intake has a gradual reduction in size up to the turbo inlet thus creating a laminar flow which could theoretically make it more efficient than a very large pipe that just butts up to the turbine housing. That aftermarket intake also having an abrupt change in diameter would create a stagnation point right at the turbo inlet, effectively making it the same diameter as the OEM intake anyway.

In the end all of the things are theoretical and even any real differences are hardly seen in the performance metrics. What Jake has given us here is the fast track to a effectively modding the car; Some people want to spend their money on noise makers and "developmental research" while others just want a grocery list to get to X amount of power.

No harm no foul either way, but Jake is shedding light on things that are advertised as "performance parts" but have minute effect on actual performance.

 

[IanCH]

Some more fluids dynamics observations;

The OEM intake has a gradual reduction in size up to the turbo inlet thus creating a laminar flow which could theoretically make it more efficient than a very large pipe that just butts up to the turbine housing. That aftermarket intake also having an abrupt change in diameter would create a stagnation point right at the turbo inlet, effectively making it the same diameter as the OEM intake anyway.

Huh? The oem pipe reduces to a much smaller size and then leaves that huge square lip of plastic on the inside of the turbo housing spaced away from the turbine wheel. The upgraded pipe basically lines up with the inside of the turbo housing. There's no redeeming qualities to the OEM pipe and it was created to be as cheap as possible with no performance in mind.

 

[Bigworm420]

All I can say is the difference from when I installed my neuspeed power module before I added all my "bolt-ons" to after I installed everything is very noticeable. I still have stock air box but removed snow guard & added k&n airfilter, turbo inlet pipe, tmd, turbo discharge pipe, twintercooler, throttle pipe(all CTS except tmd is 034). I do have an atmospheric diverter spacer(for that cool psssst sound) & I definitely feel more power then I did stock. I would like to dyno my car but im happy enough just to be able to feel the difference.

 

[Bigworm420]

Truth. removing the "snowguard" and that weather stipping in the back of the hood was a great first thing for me. Ebay DP's FTFW

What weather stripping? On the hood or the cowl? What improvement does that make?

 

[GTIfan99]

What is this witch craft? Explain please.

 

[Diggs24]

I bought a filter off ebay, cut it in half (because it wouldn't fit with the coolant hose there...too tall), and siliconed the cap back on the remaining filter. The SAI port on the block is covered with Precision Raceworks SAI delete plate. Moar wooshy noises.

 

[Lord_Flexington]

What weather stripping? On the hood or the cowl? What improvement does that make?

Its on the cowling. Thin piece of rubber that sits on the plastic. Take it off u will here a great deal more turbo/intake noise.

Same with removing the liner on the hood. Its all sound dampnening things.