What's the smallest pulley you can run on the m62 before the blower loses its efficiency? Meaning it hurts you to go to that size? While on that topice what's the smallest pulley you can run on 60# injectors? Thanks guys

 

Thats a tough question.

It has alot to do with your supporting modifaction to the car.

To start out with on the stock pulley and stock redline the blower is at a 58~59% eff.

What you have to look at is the modifcation done to the car to either cool outlet temps, or lower pressure while keeping the same or smaller pulley size.

This is achieved through cooling mods (ie dual pass endplate, option b, meth, additonal heat exchanger, killer chillers), Mid length headers 1 3/4 prim and 3" collectors.

In other cases you can increase displacement to take advantage of a blower by spinning it the same rpm or higher but seeing less boost.

60's can support any pulley size you wish on pump gas.

 

Lol I understood the injector part. My supporting mods are 1.75 in primaries 3in collector, 3in catless dp, 3in catback. I have meth w/ 5gph nozzle in a tb spacer, additional h/e w/ stock and I'm working on a big tank for the sc coolant. Don't kno what iats and that other stuff mean lol. I currently have a 2.79in pulley on now but I wanna see some more power so what do u suggest lsj?

The header,dp and cat back are not installed yet but everything else is so I'm workin on it. Right now I'm tuned at 24 deg timming

 

iat = intake air temperatures.

 

So what's the diffrence between ait and ait2?

 

iat is the air BEFORE it passes the supercharger..

iat2 is the temp of the air AFTER it passes through the supercharger..

IAT2 is the important one.

 

Anything below the stock pulley and the efficiency starts to drop off more and more. The efficiency begins to drop off pretty sharply at 14000 rpm (at the supercharger) and the efficiency really drops at 16000 rpm which is the supercharger redline.

You can help offset the loss of efficiency by helping to keep your IAT2 low so you can run more timing, however after 14000 rpm the curve in which HP increases begins to drop pretty sharply. Here is how things look from an efficiency stand point:

Stage 2 SC 14000 rpm = 6900 engine RPM
Stage 3 SC 14000 rpm = 6700 engine RPM
2.9" SC 14000 rpm = 6500 engine RPM
2.8" SC 14000 rpm = 6250 engine RPM
2.75" SC 14000 rpm = 6150 engine RPM

The 2.75" pulley will hit 16000 rpm (redline) at 7000 engine rpm.

Best "efficiency" is achieved with a 2.9" pulley.

Smallest pulley you can use before getting the biggest efficiency loss is a 2.75" pulley.

I hope that is what you were looking for.

 

Awesome ****.

 

where did you come up with these numbers? What formula are you using?

and how did you come up with the "best efficiency" is achieved with a 2.9 pulley, and the smallest pulley you can use before getting the "biggest efficiency loss" is a 2.75 pulley?

 

I don't kno where u got your stats from but it sounds pretty good to me. So I shud stay with the 2.79 pulley and not go below that. Did I get that rite? As far as cooling. Mods shud I do more? I have 2nd fm h/e w/ stock as well as meth inject. Was thinkin of dual pass and larger sc coolant bottle? Worth it or not?

 

Every cooling mod is worth it.

 

Yea I figured, some one on here told me cooling mods r like sex you can never have too much lololol

 

lol... a little too far but **** all good.

 

I thought I read somewhere the max RPM for the supercharger was 17000?

 

I would say stay on that pulley unless you want more tq. You would need to be shifting at around 6200 rpms to stay in the blower efficiency range according to his chart.

 

I usally shift at red line. But ill give his a try

 

Displacement: 1.035 Liters
Max. Outlet Pressure: 2.0 Bar
Max Speed Cont (inst.): 14,000 (16,000)
Flow at Max. Speed @ 1.8 Bar: 810 cubic meters / hour

 

Sub'd for some good info

 

I'm seeing a bit of missinformation in this thread.

 

I don't understand what they are trying to say, I'm still thinking about sex and cooling mods hmmm Intresting! Bump for more info from other people

 

well, what they are trying to say, and what the point is, is that max efficiency is going to be on the stock pulley. But you'll make more power with a smaller pulley. To get some efficiency back from the added heat of a smaller pulley, you need cooling mods. Pretty simple.

Now this "best efficiency 2.9 pulley" and "smallest pulley before getting the bigges efficiency loss is a 2.75" and these rpms of the blower at a certain engine rpms with a certain pulley, I dunno where he pulled all that from.

I know what each pulley puts the supercharger's rpms at "roughly" and I must say his numbers are a tad off. At the same time, to achieve max flow of the m62, you really have to churn some rpms out of it, and you'll need some really effective cooling mods to combat the heat and gain back some efficiency.

 

He asked about the blower efficiency, so I gave him the blower efficiency numbers. I used the efficiency numbers straight from Eaton's performance map of the M62 along with the formula I came up with myself for calculating blower speeds at certain engine speeds.

Any time you drop the pulley you are going to gain more power, don't get efficiency and power confused. The difference is that the less efficient the blower is, the less of a gain in power you will get as well.

That is why people switch to a turbo setup if they want to gain bigger HP and TQ numbers since turbos are much more efficient, or they switch to the TVS since it has better efficiency than the M62 especially at the air flow rates that the LSJ uses.

 

Looks like hes using (blower rpm * pulley size) / Crankshaft pulley size = engine rpm

(14,000 * 2.9) / 6.299 = 6445 rpm

Not sure about the efficiency claims, but I assume he means max rpm while staying under 14,000.

Here is a list of most pulley sizes and what rpm the engine would be at if spun to 16,000rpm

2.5 @ 6350 = 16,000 rpm
2.6 @ 6604 = 16,000 rpm
2.7 @ 6858 = 16,000 rpm
2.76 @ 7,000 = 16000 rpm
2.8 @ 7112 = 16,000 rpm
2.85 @ 7239 = 16,000 rpm
2.9 @ 7366 = 16,000 rpm
2.99 @ 7594 = 16,000 rpm
3.06 @ 7772 = 16,000 rpm
3.14 @ 8000 = 16,000 rpm
3.34 @ 8483 = 16,000 rpm

and the TVS, just for kicks:

2.3 @ 8,033 = 22,000 rpm
2.4 @ 8,382 = 22,000 rpm
2.5 @ 8,731 = 22,000 rpm
2.6 @ 9,080 = 22,000 rpm
2.7 @ 9,430 = 22,000 rpm
2.75 @ 9,604 = 22,000 rpm
2.8 @ 9,779 = 22,000 rpm
2.9 @ 10,128 = 22,000 rpm
3.0 @ 10,477 = 22,000 rpm
3.1 @ 10,827 = 22,000 rpm
3.2 @ 11,176 = 22,000 rpm
3.3 @ 11,525 = 22,000 rpm
3.4 @ 11,874 = 22,000 rpm

 

A smaller pulley will make more power, yes.
Best pulley for maximum power? This depends on cooling mods and your tune.
Smallest pulley available is a 2.5", but you need alot of cooling and a good tune to go that small.
stage 2 pulley is 3.066"
stage 3 pulley is 2.99"

A 2.7" is really about the smallest I would every recommand anyone to go. To run a 2.7" you need to at the minimum have methanol injection, and you should also have the dual pass and a larger heat excahnger as well.


That is the one I am using.

The efficiency claims are based off of Eaton's M62 performance map. The best efficiency for the M62 is between 4000 rpm and 10000 rpm (around 66 - 62% efficiency). Between 10000 rpm and 14000 rpm the efficiency drops off much more, but it isn'too steep of a drop(from 62 - 52% efficiency) . After 14000 and up to 16000 the blower efficiency drops pretty steeply (52 - under 40% efficiency). Since the blower redline is at 16000 rpm the performance map does not go any higher, but I would guess that the blower efficiency after 16000 rpm probably drops off pretty sharply.

 

Only thing i disagree with is the statement of "NEEDING" meth injection for a 2.7 pulley..

You dont NEED meth to run that pulley.. will it help? yes... but your car isnt just going to blow up if you dont have meth injection on the 2.7...