Supercharger Porting Q&A and Resource Thread

[djn876]

I think I follow; but, I'm pretty sure my PCV needs attention, as I've had a small drop in coolant. I had the HX install with a coolant flush done at 65k miles, now at 71.5K I'm mid-way between the Max and Min lines when the engine is warm. It's under the halfway mark when cold.

Assuming my PCV does need replacement, I don't think you're vetoing doing the other parts too, are you? (ported supercharger not included - I'm going to hold off)

If it needs to be done definitely go for it. I'm just not in favor of replacing a bunch of stuff that's not broken, unless it's high miles already. If you did a bunch of coolant work, the level will drop some over time for a little while as it self bleeds. Usually PCV is oil burning, slow coolant loss on its own is usually IC, but again could be just from the previous work.

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[Shane Horning]

It all comes down to if you don't mind removing the charger a few times and also how long you plan on keeping the car. On my car the pcv started putting coolant into eng at 79k miles. Luckily I caught it early with only a teaspoon of coolant in the oil. However it could have screwed my eng if I would have been on a long trip or wouldn't have caught it. A 170$ pcv is cheap peace of mind

[mahhdd]

Probably also the fact, that once the walls are scored the block is pretty much junk, unless you sleeve it and downsize pistons.
There isn't enough meat to bore the cylinders.

Any sort of failure = new short block. Or sleeves with new pistons etc. Then you're also looking at a custom tune, because the engine is now 2.7l.
It all adds up really really fast. Just cheaper alternatives to make more power with.

I think that's why most of the guys chasing numbers etc. Have jumped ship

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I actually didn't know this, and this sucks to hear.

[mahhdd]

If it needs to be done definitely go for it. I'm just not in favor of replacing a bunch of stuff that's not broken, unless it's high miles already. If you did a bunch of coolant work, the level will drop some over time for a little while as it self bleeds. Usually PCV is oil burning, slow coolant loss on its own is usually IC, but again could be just from the previous work.

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Actually. I didn't think of this!!! Makes total sense, and this may be my issue!! I'll check my coolant taking markings periodically to see if there's any major changes.

[Albertaholdings]

This is a great thread, but I will say unless you need to, all the maintenance crap (PCV, water pump, etc) isn't worth it at all. Swapping a charger takes an hour or two, everything in the list above is 1600+ in parts and many hours of labor, even DIY, consider injector seals, tools, etc. I already have a ported charger but needed to do PCV now and figured I'd do it all as well, it's a huge pain in the ass and not as worth it at all when just doing a swap.

Honestly don't know why everyone is concerned about that crossover pipe either. It's pretty beefy and there was nothing wrong with mine when I took it out.

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Anyone charging over a hour to switch the supercharger is ripping you off. I can do it in under 30mins, under 15mins if I'm in a hurry.

https://youtu.be/xHBhiLngWXY

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[mahhdd]

Anyone charging over a hour to switch the supercharger is ripping you off. I can do it in under 30mins, under 15mins if I'm in a hurry.

https://youtu.be/xHBhiLngWXY

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Question #27 added

[nosport]

Are you going to do any head work (porting/ polishing) or bigger valves? I’ve never seen any head specs on these engines and nobody talks about them so are they good enough from factory?


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Well. After do some inspection. Going to make a porting of intake valves and make oversized exhaust side +1mm :)

[djn876]

Anyone charging over a hour to switch the supercharger is ripping you off. I can do it in under 30mins, under 15mins if I'm in a hurry.

https://youtu.be/xHBhiLngWXY

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No one charges me anything because I do my own work. I could do it faster but I just prefer taking my time since it isn't like I'm doing it every day, and would include system bleeding the too. Plus if the charger is off, I'll use the FCP warranty to swap ICs for free which adds some time as well.

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[djn876]

It all comes down to if you don't mind removing the charger a few times and also how long you plan on keeping the car. On my car the pcv started putting coolant into eng at 79k miles. Luckily I caught it early with only a teaspoon of coolant in the oil. However it could have screwed my eng if I would have been on a long trip or wouldn't have caught it. A 170$ pcv is cheap peace of mind

I get that for sure that's why I said if higher miles might be worth it. But I will say I have zero desire to do that coolant crossover pipe again, and even at 5 years and 70k, it wasn't brittle at all or had any damage to it. Not worth it IMO. The rest of the work wasn't bad and I don't have any issue pulling the charger to do work every now and then if required. I just feel a lot of times it gets made out to be easy peasy and take an extra 20 minutes to swap all those other parts and that's not the case. Again though, i'm for preventive maintenance at the right time, but not every time it's off.

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[mahhdd]

What I've learned so far is in negative da 3.1pr, 0 da 3.2pr, 1000da, 3.3pr, 2000da 3.4pr, 3000+ da 3.4 to 3.5 pr.

I'm coming back to this, and it's my first time paying attention to Density Altitude. I'm in Georgia, and I was pretty shocked to learn it could fluctuate so much! I'm currently -650 DA and it was +1700 DA the other day. What's the philosophy for planning around these fluctuations???

[Shane Horning]

I'm coming back to this, and it's my first time paying attention to Density Altitude. I'm in Georgia, and I was pretty shocked to learn it could fluctuate so much! I'm currently -650 DA and it was +1700 DA the other day. What's the philosophy for planning around these fluctuations???

Well actually I kinda worded it wrong, I would say it should more be based of altitude. However just a baseline, kinda take an average da and match the pr to that.

[mahhdd]

Well actually I kinda worded it wrong, I would say it should more be based of altitude. However just a baseline, kinda take an average da and match the pr to that.

Throw out a min and max number for reliability in GA
I don't want to blow motors or be lifting heads

[Fresh.S4]

Anyone charging over a hour to switch the supercharger is ripping you off. I can do it in under 30mins, under 15mins if I'm in a hurry.

https://youtu.be/xHBhiLngWXY

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was gonna call you out on the BS time because im at about 30min.

daaaaaaaaaaaaamn you fast homie!!!

[Albertaholdings]

was gonna call you out on the BS time because im at about 30min.

daaaaaaaaaaaaamn you fast homie!!!

Only thing you don't see in the video is me cutting the belt because I wasn't going to use it again. I highly recommend getting a belt tool if you don't have one. I also don't have the side pieces on ever as they don't fit with my big blower. But that's just 4 t25's. Really can do a swap in under 15mins. Longest part is usually the getting the belt back on as I run them as tight as I can get them.

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[Shane Horning]

Throw out a min and max number for reliability in GA
I don't want to blow motors or be lifting heads

If you see negative da I'd run 3.3pr

[sepheroth86]

If you see negative da I'd run 3.3pr

All this sort of talk had me worried for a bit. Here in Michigan I'd imagine similar winter time DA as upstate NY. But after running the numbers again, my plan on 189 crank and 57.75 blower will work out to a nice 3.27 ratio. 👌

[Shane Horning]

All this sort of talk had me worried for a bit. Here in Michigan I'd imagine similar winter time DA as upstate NY. But after running the numbers again, my plan on 189 crank and 57.75 blower will work out to a nice 3.27 ratio.

Yes that's a nice pr for us close to sea level!

[hunter_killer]

I’m slightly confused, didn’t you say earlier in this thread that in negative DA to run a 3.1 PR or have I missed something along the way?


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[Shane Horning]

I’m slightly confused, didn’t you say earlier in this thread that in negative DA to run a 3.1 PR or have I missed something along the way?


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There isn't a specific pr for a specific da but if you only run your car in negative da I'd recommend somewhere around 3.1 to 3.2ish. However da is always changing so obviously can't always be changing pr but just something to keep in mind when buying pulleys

[hunter_killer]

There isn't a specific pr for a specific da but if you only run your car in negative da I'd recommend somewhere around 3.1 to 3.2ish. However da is always changing so obviously can't always be changing pr but just something to keep in mind when buying pulleys

That’s what I thought, just wanted make sure I was on the same page.


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[wootwoot]

Does a ported supercharger provide gains under partial throttle conditions or would you only notice a performance difference at WOT?

[Shane Horning]

Does a ported supercharger provide gains under partial throttle conditions or would you only notice a performance difference at WOT?

I'll let someone else answer that as I've ran a ported charger basically right after going dp, but I would think its probably not a big increase at part throttle

[RoofRails]

Does a ported supercharger provide gains under partial throttle conditions or would you only notice a performance difference at WOT?

Not really, not in the way say a dual pulley upgrade would make your throttle feel more responsive. A ported blower makes power by creating more boost by reducing air flow restrictions. Under part throttle conditions your BPV is partially open and your ECU is controlling the boost to make the torque your right foot has requested. Under WOT the bypass is closed and allows the ported blower to make more PSI then your non ported blower. My Ported blower feels the same at part throttle as my stock blower.

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[mahhdd]

I'll update my original post a bit later. It's needing to be updated.

How does porting a supercharger effect the supercharger whine? Does it make it a lower/higher pitched whine? I know it increases the volume?

Another question I had was about drivability/streetability. Someone said that a port job would increase drivability; but, I don't fully understand why or how.

[hunter_killer]

^ To add to your last question; there was somebody who didn’t like the aggressive porting job and ended up getting a less aggressive port job. Why would a aggressive port not be ideal for a daily driver?


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[BrokeBichB8]

Flame suit on.

How come nobody trims/modifies the rotors? The rotors are thick on the inlet end where they could be much thinner no?

[sepheroth86]

Flame suit on.

How come nobody trims/modifies the rotors? The rotors are thick on the inlet end where they could be much thinner no?

I believe that the rotors seal against the case and one another to push the air.

[BrokeBichB8]

I believe that the rotors seal against the case and one another to push the air.

That is a true statement. But why do the rotors have to seal against each other along the whole supercharger? The spot where the supercharger rotors seal moves as the rotors turn.

I only ask because the rotors packs are supposedly mass produced to fit other charger designs, and its one of the last places of the charger that remains untouched.

[sepheroth86]

I believe that if there were efficiency to have been gained in that area of the rotor pack that Eaton would have taken it. They have been losing market share due to inefficiency and cost to turbochargers for years. The TVS lineup was them putting all their engineering might into closing that gap.

Essentially, the only difference in the old style roots blowers and the TVS is the rotor itself.

[BrokeBichB8]

You've got to remember they're trying to make money too though, and sacrificing efficiency for extra machining intricacy and time is something they would do. Why get another 10-15 hp and 5% blower efficiency when it will cost an extra 5 hours of machine time??? That's why we port our superchargers in the first place. The charger casting is meant to be a consumers balance of power and cost effectiveness.

The charger is designed for the consumer in mind. Eaton would have definitely done some things different if they designed the charger to be spun at a 3.26+ pulley ratio with high performance fuel. Not saying its a bad design with huge flaws, but engineers do cut corners for $$.

Which leads me to return. If the rotors seal against themselves and the twisting rotor moves that seal, why not thin out the rotor tips by the inlet and get more inlet airflow. Im thinking it would only improve efficiency?

[sepheroth86]

You've got to remember they're trying to make money too though, and sacrificing efficiency for extra machining intricacy and time is something they would do. Why get another 10-15 hp and 5% blower efficiency when it will cost an extra 5 hours of machine time??? That's why we port our superchargers in the first place. The charger casting is meant to be a consumers balance of power and cost effectiveness.

The charger is designed for the consumer in mind. Eaton would have definitely done some things different if they designed the charger to be spun at a 3.26+ pulley ratio with high performance fuel. Not saying its a bad design with huge flaws, but engineers do cut corners for $$.

Which leads me to return. If the rotors seal against themselves and the twisting rotor moves that seal, why not thin out the rotor tips by the inlet and get more inlet airflow. Im thinking it would only improve efficiency?

While twin screw are a bit of a different animal. Whipple makes performance, custom superchargers with an emphasis on efficiency and performance. They do not perform what you are talking about doing. They have spent millions on custom tooling and equipment, so I would think if there were gains in your idea Whipple would have done it.

As far as the case goes, that is all Audi's inefficiency. The sizing of the blower fit Audi's needs for performance on these engines.

Eaton offers multiple rotor pack sizes if more performance is desired. Audi didn't want more performance.

I read somewhere that it takes around 15 minutes to machine a set of rotors.

If you want, try your theory on your rotors. I would measure inlet and output cfm before and after, if possible (I'd think a flow bench is needed here). Remember that more heat will increase boost PSI so boost pressure is not always an accurate measure of increased flow.

[mahhdd]

^ To add to your last question; there was somebody who didn’t like the aggressive porting job and ended up getting a less aggressive port job.

Really? On here?

What were his gripes?

[hunter_killer]

Really? On here?

What were his gripes?

slowwa6 on YT said he traded his ported blower for a more aggressive blower stating the other guy didn’t like how aggressive it was for driving. That’s all the info given out. Hence why I was curious if there was an answer to be given or not.


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[RoofRails]

Flame suit on.

How come nobody trims/modifies the rotors? The rotors are thick on the inlet end where they could be much thinner no?

Have you seen this done on other supercharged platforms or are you just spit balling ?

[sepheroth86]

Have you seen this done on other supercharged platforms or are you just spit balling ?

Whipple spent millions of dollars on new equipment and an entire proprietary process to make the rotors as tight as possible to themselves and the case.

While our blowers are different than a twin screw, I would imagine the same principles apply.

[RoofRails]

Whipple spent millions of dollars on new equipment and an entire proprietary process to make the rotors as tight as possible to themselves and the case.

While our blowers are different than a twin screw, I would imagine the same principles apply.

I agree with you 100%. Their dimensions to the case and each other are critical and the length and diameter determine the volume of air they will flow so I was just curious where the idea of removing material from them to flow more came from.

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[Shane Horning]

slowwa6 on YT said he traded his ported blower for a more aggressive blower stating the other guy didn’t like how aggressive it was for driving. I believe Shane may of ported that aggressive blower. That’s all the info given out. Hence why I was curious if there was an answer to be given or not.


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Please don't start rumors. I sold that charger to a fellow and his shop, Ostar motorsports, refused to install it because I had the center support removed. They claimed that it wouldn't last more than a few weeks . They funny thing is I have dozens of those ports running without a single issue. Never was there a problem that a fellow ran a good aggressive port and didn't like it.

[sepheroth86]

I agree with you 100%. Their dimensions to the case and each other are critical and the length and diameter determine the volume of air they will flow so I was just curious where the idea of removing material from them to flow more came from.

I suspect that in order to get proper scavenging that the inlet end of the rotor needs to seal against the case and create a sharp cutoff point. So making them narrower on the inlet end would then hurt performance.

However, that is only a suspicion since I have not done any testing on that matter and my understanding of fluid dynamics is limited at best.

[hunter_killer]

Please don't start rumors. I sold that charger to a fellow and his shop, Ostar motorsports, refused to install it because I had the center support removed. They claimed that it wouldn't last more than a few weeks . They funny thing is I have dozens of those ports running without a single issue. Never was there a problem that a fellow ran a good aggressive port and didn't like it.

Edited my post then* Definitely not starting rumors (or wanting to) about anyone, just posting up back up to the reason of my question. Obviously it was stated wrong from Thornton then about why the blowers got switched.


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[BrokeBichB8]

Have you seen this done on other supercharged platforms or are you just spit balling ?

I haven't see a single person modify a rotor pack. Online you'll find a lot of supercharger port work of the casing. But I mean there's not a lot of people who modify superchargers in the world as a whole. lol. I work in a place that uses a lot of screw based material moving equipment and the leading edge of every screw usually has some kind of edge taper or smoothing/thin leading edge. My question/idea comes about because I had my supercharger apart when I was porting it, and I was just staring at each inlet, surface, and edge thinking, "How can flow be smoothed or improved?" Sharp edges create, heat/friction/turbulence and that is bad for flow. So I tried smoothing every single edge and rounding every single corner in the charger. except for the rotor packs...

I suspect that in order to get proper scavenging that the inlet end of the rotor needs to seal against the case and create a sharp cutoff point. So making them narrower on the inlet end would then hurt performance.

However, that is only a suspicion since I have not done any testing on that matter and my understanding of fluid dynamics is limited at best.

If I didnt change any of the contact points of the rotors, and they sealed against the case the case the same, just thinner blades at the inlet, do you think that would effect scavenging?

Ive got an extra rotor pack which has some peeling coating, so a good candidate, but I just wanna discuss if anything would be a total wreck of the charger design. lol I mean I hate to be devils advocate on this forum, but I cant just go to the local car meet and ask, even guys with gt500's got no clue what's in their supercharger. lol

Thanks