Andy's 2.8 Supercharger Build Thread

[b7_Andy]

Hey man so the max is 16,000 rpm

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Sweet so I’m just barely under max speed haha... I’ve spent forever trying to find a definite answer to that, thanks haha!

[Calderfer2665]

Sweet so I’m just barely under max speed haha... I’ve spent forever trying to find a definite answer to that, thanks haha!

What size pulley you running?


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[b7_Andy]

What size pulley you running?


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2.8” pulley on the supercharger

[GrapeBandit]

How did out figure your SC is at max rpm while only pushing 7.5psi? Like what formula did you use? Seems off because the m62 is good to around 15psi

[b7_Andy]

How did out figure your SC is at max rpm while only pushing 7.5psi? Like what formula did you use? Seems off because the m62 is good to around 15psi

I divided the crankshaft pulley diameter by the supercharger pulley diameter to get the number of rotations the supercharger makes per rotation of the crankshaft then multiplied by my redline (6800 rpm). It’s not all about boost, it’s really mass airflow that’s important. The MP62 will make twice as much boost on Miatas that have a 1.6 and much smaller intake ports because air spends more time between the supercharger and the cylinders getting pressurized. The 2.8 can flow way more air because more cylinders, bigger intake ports, and the PES manifold has pretty big ports too so the air flows faster into the cylinders before it can reach really high pressures.

[Calderfer2665]

That’s why I asked as well? I’am running the smaller pulley and it’s about 10-11psi with no problems?


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[b7_Andy]

That’s why I asked as well? I’am running the smaller pulley and it’s about 10-11psi with no problems?


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What elevation do you drive at? I know at sea level this pulley should make 10psi. Unlike turbo setups or even the supercharger in the B8s, boost isn’t regulated with this kit so your peak boost is pretty much whatever your blower can put out at redline. So boost is directly related to pre-supercharger air pressure. I live 6,000 ft above sea level and peak at 7.5 psi... when I drive through the Eisenhower tunnel at 12,000 ft above sea level I can only reach about 6 psi at redline. So I figure at sea level I’d probably peak at 9 psi which means I’m losing about 1 psi for all the hacking I did to my supercharger.

[GrapeBandit]

I divided the crankshaft pulley diameter by the supercharger pulley diameter to get the number of rotations the supercharger makes per rotation of the crankshaft then multiplied by my redline (6800 rpm). It’s not all about boost, it’s really mass airflow that’s important. The MP62 will make twice as much boost on Miatas that have a 1.6 and much smaller intake ports because air spends more time between the supercharger and the cylinders getting pressurized. The 2.8 can flow way more air because more cylinders, bigger intake ports, and the PES manifold has pretty big ports too so the air flows faster into the cylinders before it can reach really high pressures.

So are you saying the m62 cant produce 1 bar on a 2.8 v6?

Its going to produce 1 bar on my mercedes 2.3L 4cyl(only 6,000 redline)when I get it back from the machine shop. Not much smaller than your engine and lower redline.

[b7_Andy]

So are you saying the m62 cant produce 1 bar on a 2.8 v6?

Its going to produce 1 bar on my mercedes 2.3L 4cyl(only 6,000 redline)when I get it back from the machine shop. Not much smaller than your engine and lower redline.

It’d probably make 1 bar if it was a 4 cylinder or if I had 2.7 heads and a manifold similar to a 2.7 manifold because the airflow would be more restricted so it’d build up pressure faster. But that wouldn’t make much sense because it wouldn’t be putting air into the engine any faster. Horsepower isn’t all about boost, air pressure is only consistent with the volume of your intake system, port sizing in the heads and engine displacement. Smaller intake volume=more pressure but less flow. Making a ton of boost is good for power, but there’s guys with corvettes that are making almost 1,000 hp on 12 psi because 12psi in their giant intake system is actually moving waaaaaay more air than like 30 psi in a 4 cylinder.

[Joe Jr.]

sounds like a fun car. I'd like to see it sometime. Do you do any of the meets with the guys and the rocky mountain Quattros? I haven't just because it seems like its mostly about new cars and RS cars etc.

[b7_Andy]

sounds like a fun car. I'd like to see it sometime. Do you do any of the meets with the guys and the rocky mountain Quattros? I haven't just because it seems like its mostly about new cars and RS cars etc.

I used to go to a lot of Denver Audi meets in the past. I haven’t been to any in a while mainly because I’ve been so busy with school and work, but I’d be down to go to a Rocky Mountain quattros meet sometime. They’ve got their next one like the 20th right? It does seem like all fancy Audi’s that go though, I’d have to hide mine in the back corner or something haha

[Joe Jr.]

yeah now that you say that. i saw that they are doing something on the 20th. I was at the Lafayette cars n coffee last Saturday. it was a good day for it. Lots of cars out.

[BonusParts]

What elevation do you drive at? I know at sea level this pulley should make 10psi. Unlike turbo setups or even the supercharger in the B8s, boost isn’t regulated with this kit so your peak boost is pretty much whatever your blower can put out at redline. So boost is directly related to pre-supercharger air pressure. I live 6,000 ft above sea level and peak at 7.5 psi... when I drive through the Eisenhower tunnel at 12,000 ft above sea level I can only reach about 6 psi at redline. So I figure at sea level I’d probably peak at 9 psi which means I’m losing about 1 psi for all the hacking I did to my supercharger.

He's at sea level.

Good numbers, thats about what the standard 6psi 3.xx pulley does at sea level.

I kinda miss mine a bit

BY the way, did you want to maybe switch to Coil on Plug? I have a harness I made for mine, then never used and sold the car...

[b7_Andy]

He's at sea level.

Good numbers, thats about what the standard 6psi 3.xx pulley does at sea level.

I kinda miss mine a bit

BY the way, did you want to maybe switch to Coil on Plug? I have a harness I made for mine, then never used and sold the car...

Like a B7 style coil conversion?

[Kefe8302]

Hey Andy, what size belt do you have match with your 2.8 pulley on the G2? I'm using a 6pk 1970, Feels a little lose.

[b7_Andy]

Hey Andy, what size belt do you have match with your 2.8 pulley on the G2? I'm using a 6pk 1970, Feels a little lose.

Looks like I ordered a 1968.5 mm belt. The continental part number is 4060775.

[Kefe8302]

Much appreciated. Thanks for this build write up by the way. It gave me the confidence to install my AEM fuel pump.

[b7_Andy]

Much appreciated. Thanks for this build write up by the way. It gave me the confidence to install my AEM fuel pump.

No problem, much more to come with the write up when I finally get around to doing it lol

[b7_Andy]

So last week I took a road trip through Scottsdale, AZ and then to Park City, UT to ski and then back to Denver. Total trip was 2,300 miles and the car somehow didn’t breakdown Scottsdale is about 1,500 ft above sea level so I was making about 8.5 psi while I was there and man did the car haul ass! I did find another rebuilt rotor pack for sale on eBay that I’m thinking I’ll get for this supercharger so I can have fresh rotors. I’m pretty sure the boost I’m losing is from how beat up the rotors are and all the material I took off of them from resurfacing. I think with new rotors I could probably get 2 psi back which would maybe translate to like 30 hp lol. I will update if/when I swap the rotor pack.

[Joe Jr.]

cool picture! I was just there in November and going back again in March. I was debating taking my b5, and i think i decided against it. lol. but yeah its amazing when you leave Colorado and go somewhere with air how you notice the extra power the car has.

[b7_Andy]

cool picture! I was just there in November and going back again in March. I was debating taking my b5, and i think i decided against it. lol. but yeah its amazing when you leave Colorado and go somewhere with air how you notice the extra power the car has.

It makes such a difference, I wish I could see how much power my 3.2 B7 has at sea level.

[b7_Andy]

Well I sliced my finger open and can't work for a couple days so I finally got the free time I needed to update this thread lol. All the DIY stuff I did is now covered in the first two posts if anyone wants to see. It's been around 5,000 miles that I've been driving this setup and so far I'm still really happy with it and haven't run into any big issues. Here's some of my future planning for the car...

-Rebuild the supercharger with a new rotor pack in hopes to get to 9 psi at altitude.
-Get an E85 tune made for the car, hopefully before summer when it starts getting real hot again.
-Redo a lot of the exhaust... I plan on getting an XS-Power twin 2 B5 S4 catback and modifying my downpipes again. I don't like having the flex pipes at the lowest point of the car, so I want to relocate them to the downward section of the downpipes like how they are in the B7s. I also want to add interchangeable cats/test pipes with V-bands to the last flat section of the downpipes so I can switch out cats or test pipes in a matter of minutes for having to pass emissions or whatnot. Currently I'm running the stock catback which is literally just rotting. My exhaust also reduces from dual 2.5" to dual 2" to single 2.36" so from beginning to end I'm getting a 60% reduction in flow area which combined with the rotting catback makes these car sound awful. It's raspy as hell haha
-Convert my front suspension to B7 suspension. I have a spare set of stock B7 front coilovers with 55,000 miles on them and B7 spindles. This way I'll have 1,000 more brake options so I can actually put decent brakes on this car and the suspension should ride a little nicer.

[Joe Jr.]

wow, you've been driving the thing alot. I barely put 4k on my car last year. I really like running the e85 in the summer also, and its definitely a power boost. I like the plans for updating the suspension. I spent most of last year getting the suspension on mine sorted...new 034 control arms, shocks/springs, engine mounts...ect.

[b7_Andy]

Ya half the miles were from the road trip haha... and and yes motor mounts! My stock 3.2 mounts that I put in there have gotten destroyed since it’s been supercharged so I definitely need some good motor mounts in there.