[Snowkan]

Hey all;

Interested in maybe supercharging my 15 RT 5.7. I have a 6.4 intake wired up..Should I be looking for a 5.7 or 6.4 supercharger kit? I have unlocked PCM and tuned

 

[ChallyTatum]

So you have a 6.4 intake on a 5.7? Do you have any other mods to your engine? Headers, cam, heads...? What is your end goal...daily drive with more power or do you plan on drag racing?

There are 2 types of supercharger systems out there (1) positive displacement (does not use stock intake) or (2) centrifugal that pipes up to the stock intake (i.e. procharger).

Then there are varying levels of boost with 8 psi being considered safe for a 5.7 if use run +91 octane. Higher than that it is recommended to get drop-in forged pistons. You can get by with 10 psi on a stock engine but you will need to run water/meth. Some say the positive displacement superchargers should not run water/meth as it can corrode the rotors.

If you already have an unlocked PCM and tuner that is great and saves you ~$1k but you still need a tune which depends on the state of your car. If it is stock then companies like edelbrock and magnuson have tunes ready but they still require tweaking which is usually done by logging runs on the tuner and emailing. If it has other mods your best bet is to talk with one of the forum vendors (usually they chime in) as they usually have more experience tuning superchargers with other power adders.

I personally went with a Magnuson 2300 8lb set-up on my 2015 5.7 (kit also works for a 6.4) and I went through API. It came with a larger fuel pump to minimize the chance of running lean at WOT. It took several back and forth logs via email to get the tune dialed in. I also had issues with the kit which API corrected (wrong nozzle was sent, fuse tap was for a pre-2015, wrong pulley was sent).

The magnuson is a roots type blower just like the edelbrock and is very quite. Edelbrock now sells a 2650 blower which performs better than the 2300. There are other systems like whipple and K&B which are compressor type superchargers that tend to have a more pronounced whine.

This is just some introductory info on the subject. I suggest you search the forum, figure out what you want in terms of power/driveablility and talk to some of the vendors.

 

[Snowkan]

I have SRT headers, exhaust and hellcat air intake. I don't have a drag strip around here so mostly daily driven with more power.. I haven't seen alot of 15+ 5.7 supercharged!! Did you install yourself?

 

[ChallyTatum]

I have SRT headers, exhaust and hellcat air intake. I don't have a drag strip around here so mostly daily driven with more power.. I haven't seen alot of 15+ 5.7 supercharged!! Did you install yourself?

Yup, installed the magnuson, pinned the crank (bought a cheap 90 degree air drill from harbor freight) and fuel pump (bought the hat ring removal tool which makes it sooo much easire) myself, although I did have a friend help me position the supercharger on top of the engine (can be done with a cherry picker). The install can be done over a weekend (mine took a week because I was not sent the shorter IAT sensor) and on the 5.7 there is no need to remove the front clip to install the intercooler radiator (I did have to drill into one of the air deflectors to run one of the coolant holes). Compared to a cam and header install, it is a piece of cake and it gives you ~20HP per psi with 8psi being safe limit on a stock 5.7. Kit cost $7800 with tuner, PCM and API fuel pump (~$49/HP) but you can get it cheaper now with all the end of year deals. Although I would wait for the bigger 2650 maggie instead of getting the 2300. Or you can go with the Edelbrock but not sure how they are handling the increased fuel requirement? I am now in the process of installing long tube headers (2 inch primaries) from stainless works because the cast manifolds are restrictive. Fuel mileage does drop by ~2-3MPG but it's because I am always droppin the hammer, oh and I run 93. But for me it is all about the SPG (smiles per gallon).

 

[spoolboy]

I hope/suspect you meant ~20hp per psi and not ~2hp!

16hp for $7800 is not a great deal.
160hp isn’t bad.

 

[ChallyTatum]

I hope/suspect you meant ~20hp per psi and not ~2hp!

16hp for $7800 is not a great deal.
160hp isn’t bad.

Thanks for the catch, typo corrected. I would like to see any other mod get you 160hp without breaking the bank. Don't get me wrong $7800 is a lot of coin to most (myself included) but the prices I have seen for strokers getting near those HP figures is significantly more. A while back I posted some $/hp assuming all labor was performed by the DIY'er. But if I had a chance to do it all over today, I probably would have bought a used manual Hellcat. But since I am already in the rabbit hole and I love to wrench...what the hell.

 

[stevewhite]

unfortunately we sold out this morning but we have 10 more kits coming, basic Magnuson kit is on sale for $6595.00 + free ship, for 8 psi, add 99.00 for the pulley, 569.00 for fuel system and 425 additional for tuning.....be glad to assist

Luke V>

 

[ChallyTatum]

unfortunately we sold out this morning but we have 10 more kits coming, basic Magnuson kit is on sale for $6595.00 + free ship, for 8 psi, add 99.00 for the pulley, 569.00 for fuel system and 425 additional for tuning.....be glad to assist

Luke V>

You probably get this a lot but are the new magnuson TVS2650 available?

 

[stevewhite]

You probably get this a lot but are the new magnuson TVS2650 available?

only about 12 times a day, no, and now mid to late January for the Hellcat version and probably a month later for the 6.4 version
Luke:frown:

 

[Mcovey1977]

I have a question. Do you think I can get away going 9psi at altitude in my challenger? Its a stock motor and I know I should be at 8psi, but I lose so much horse power in Denver because of the altitude. I have a 2015 challenger R/T whipple supercharger. I’m using 3.50 pulley and I want to go to a 3.375.

 

[ChallyTatum]

I have a question. Do you think I can get away going 9psi at altitude in my challenger? Its a stock motor and I know I should be at 8psi, but I lose so much horse power in Denver because of the altitude. I have a 2015 challenger R/T whipple supercharger. I’m using 3.50 pulley and I want to go to a 3.375.

I have heard of people going to 10-11PSI on stock but with water/meth and they tuned for it (also was told by Wyatt at Arrington this was done on some customer builds with no issues but that they must religiously monitor their water/meth tank). But honestly, this is a discussion you should have with the place you are getting the kit & tune from.

 

[us1champ]

You already live in what I call lean air. Don’t do it. If you do get the tune adjusted
You are playing s fine line with a stock motor and Denver air


Sent from my iPhone using Tapatalk

 

[stevewhite]

for reliability i would stay at 8 psi max, especially where you are
Luke

 

[ChallyTatum]

Actually at high altitude there is a lack of air so if anything he would be running rich...it is when he drives at sea level where there is a risk of running lean and detonation. There are guys running 10psi on stock 5.7 with water/meth at sea level which I would consider more of a risk.

Luke on a side note I thought 8psi was max on the 5.7 and 6psi 6.4 on stock internals (without water/meth)...but I am seeing more posts where guys with 6.4 are running 7-8psi. Are you seeing this trend or is it all in my head?

 

[spoolboy]

A supercharger is just a compressor.

It takes inlet pressure and increases it by a ratio. Lets say atmospheric pressure is 14psi and you want to run “7psi of boost”. You need to run your blower at 1.5:1 pressure ratio. Or an absolute oulet pressure of 21psi.

Your pressure ratio is adjusted by blower speed (controlled by pulley size or turbine size/shape and/or wastegate) and the shape and/or size of the rotors or compressor wheel (depending on what kind of supercharger we’re talking about).

If you increase the pressure going into the compressor to 16psi, the output will be “8psi of boost” or an absolute pressure of 24psi if everything remains the same.

If you run the blower harder (higher pressure ratio) by starting with a lower inlet pressure and turning it faster, it will create more heat and loss from turning force.

This is a simplified explaination because volume also comes into play. Put a small blower on a large engine and you may not make any “boost” because “boost” is only a measure of “backpressure” or air that is stacking up in the inlet waiting to get into the engine when the valves open.

In short, if you are seeing 7, or 8, or whatever PSI of boost, it does not matter what altitude you’re in. The performance will be about the same, minus losses from heat and having to drive the compressor.

 

[spoolboy]

Denver station pressure:

https://forecast.weather.gov/product.php?issuedby=BOU&product=OSO&site=bou

So right now you're breathing about 12.5psi.

 

[ChallyTatum]

Nevermind, I was wrong.

 

[spoolboy]

Copied from a forum that copied it from a forum. PR = Pressure Ratio. Inlet to outlet ratio.

Here is some info from another forum and thread (an STI guy in Colo near Pike's Peak...) maybe it will help, but at the very least I thought since it was from your back yard you'd find it interesting none the less:

Just for fun I will put some numbers to the Pikes Peak example:

Lets take a stock STi with the stock VF39 turbo.

1ST - calculate the absolute pressure/air that you are pushing through the engine:
-At sea level:
run 14.5 stock psi + 14.7psi (atmospheric pressure) = 29.2psi total.
-At 6000ft ~ the beginning of Pikes Peak hill climb:
run 14.5 stock psi + 11.4psi (atmospheric pressure) = 25.9psi total.
-At 14,380ft ~ the end of Pikes Peak hill climb:
going off the above example I have noticed about 1.1psi atmospheric drop for every 2000ft you go up (6000ft ~ 3.3psi pressure drop). So 14.5psi + 8psi (atmospheric pressure) = 22.5psi total

2ND - calculate the % of air loss you experience compared to sea level (aka roughly the amount of hp loss you will experience with a stock STi):
-at 6000ft 25.9 / 29.2 = 88% so you have 12% less pressure going into the engine
-at 14,380ft 22.5 / 29.2 = 77% so you have 23% less pressure going into the engine

NOW same comparison for a NA car in terms of how much % less air:
-at 6000ft 11.4 / 14.7 = 77% so you have 23% less pressure going into the engine.
-at 14,380ft 8 / 14.7 = 54% so you have 46% less pressure going into the engine.

3RD - NOW for the good part - calculate the PR you would have to run on the STi to get the same 14.5psi of RELATIVE boost at each elevation:
-at sea level - (14.5 + 14.7) / 14.7 = 1.98 PR
-at 6000ft - (14.5 + 11.4) / 11.4 = 2.27 PR
-at 14,380ft - (14.5 + 8) / 8 = 2.8 PR

Some interesting notes on the above example:
-Just to run the same relative boost pressures WHILE still experiencing a 23% loss in air/power you have to spin the turbo at a PR of 2.8 instead of 2.0 at sea level.
-The above example doesn't take into account less efficient affects of intercooling with less dense air.
-The above example doesn't take into account lower VEs from higher turbine speeds from higher PRs.
-The fact that you have vacuum in the intake tube between your air filter and the compressor wheel/inlet. The short of this is you have to add an extra 0.2-0.3 to your PR since your turbo doesn't even get to work with the above atmospheric pressures I just told you. (This is starting to get into the real world side of things [heh]).

Now you might say well just turn up the boost to compensate right? Well lets just see what that would do to the PR at 6000ft.

So we want to run the same pressure through the engine at 6000ft as we did at sea level right?
-Sea level total pressure = 29.2psi
-So at 6000ft 11.4psi (atmospheric) + x = 29.2 where x is the amount of boost your turbo has to run which would be 17.8 psi.

SO the PR for running 17.8 psi would be (17.8 + 11.4) / 11.4 = 2.56 PR compared to 1.98 PR at sea level.