[Torgus]

Originally Posted by CobraMarty

So the stock harmonic balancer is about 5.375".
ESS SC pulley is 4.52"(115mm).
Pulley ratio is 5.375/4.52= 1.19:1 pulley ratio. At 7500 engine rpm that is 8919 SC rpm.
That is on a SC with max rpm 14,450.
No wonder the boost curve is so lazy and low boost on top of 6psi.

A 4" SC pulley will have a pulley ratio of 5.375/4= 1.34 pulley ratio. At 6500rpm that is 8710SC rpm and would make about 6psi but will have a more ramped up boost curve.

A 3.75" SC pulley will have a PR of 5.375/3.75= 1.433. So at 6200rpm that is 8885 SC rpm and again about 6psi at 6200rpm. And an even more aggressive boost curve.

So the problem is that over 6psi, the charge intake air temps start getting too high and cause detonation and issues. Need some type of intercooling. Water/meth injection or ethanol fuel. FMIC and water-air IC unfortunately are a packaging problem.

So if the max boost non-intercooler is 6psi, and on an engine that can rev to 7200rpm, ESS has to pulley accordingly which is why there is such a 'lazy' boost curve and little to no gain at low-mid rpm, even up to about 4500rpm.

My idea is if you change your driving style and engine to rev limit to 6200rpm, you can now still pulley to target about 8900 SC rpm and about 6psi. This will have a much more aggressive boost curve and more power down low and in the mid rpm range and more torque down low.

If you solve the high charge IAT issue, you will then be able to run more boost, even up to 12-15psi like the BPC turbo FMIC N52 'Alice'.

Water/meth injection is cheap and pretty easy to install. That would get my vote over trying to run 100% E85 any day of the week. + you get the octane boost with the added cooling for a win win.

No one has done this before? Run meth and a smaller pulley?

[Noir]

Originally Posted by CobraMarty

So the stock harmonic balancer is about 5.375".
ESS SC pulley is 4.52"(115mm).
Pulley ratio is 5.375/4.52= 1.19:1 pulley ratio. At 7500 engine rpm that is 8919 SC rpm.
That is on a SC with max rpm 14,450.
No wonder the boost curve is so lazy and low boost on top of 6psi.

A 4" SC pulley will have a pulley ratio of 5.375/4= 1.34 pulley ratio. At 6500rpm that is 8710SC rpm and would make about 6psi but will have a more ramped up boost curve.

A 3.75" SC pulley will have a PR of 5.375/3.75= 1.433. So at 6200rpm that is 8885 SC rpm and again about 6psi at 6200rpm. And an even more aggressive boost curve.

So the problem is that over 6psi, the charge intake air temps start getting too high and cause detonation and issues. Need some type of intercooling. Water/meth injection or ethanol fuel. FMIC and water-air IC unfortunately are a packaging problem.

So if the max boost non-intercooler is 6psi, and on an engine that can rev to 7200rpm, ESS has to pulley accordingly which is why there is such a 'lazy' boost curve and little to no gain at low-mid rpm, even up to about 4500rpm.

My idea is if you change your driving style and engine to rev limit to 6200rpm, you can now still pulley to target about 8900 SC rpm and about 6psi. This will have a much more aggressive boost curve and more power down low and in the mid rpm range and more torque down low.

If you solve the high charge IAT issue, you will then be able to run more boost, even up to 12-15psi like the BPC turbo FMIC N52 'Alice'.

thanks for the information!

[Kubricks]

Originally Posted by CobraMarty

Unfortunately the problem is partly the 'large' SC and the engine rpm to 7000.

With my car and auto and my driving style, I rarely if ever rev above 6000.
If you set the rev limiter to 6000, you could then pulley it to have max SC rpm at the 6000rpm instead of 7000rpm. This will make more boost down low and more mid range power.

I understand the boost curve improvement (ie., more mid range with agressive pulley) but arn't you just giving up 1200rpm of mechnical gearing advantage? That's a lot.

Think F20C, it has a mild torque output but still manage to be pretty quick in real world because of the 9000rpm rev limit.

[CobraMarty]

Yeah but auto not manual.

I drive and auto shifts below 5000rpm 99% of my driving. 1% 5k to 6k.
I could probably count on my fingers and toes how many times I have ever seen over 6.5k.

More TQ from 2k to 5.5k is still a pretty wide range.

But this idea/concept is not for everyone. I just like using/feeling boost all the time and not just when i wind it out, 9k that's impressive. But then again I'm an old fart.

[Taskmaster]

The F20C has tight gearing (mechanical torque multiplication) and light weight/high HP. Love that engine.

[Kubricks]

Originally Posted by CobraMarty

Yeah but auto not manual.

I drive and auto shifts below 5000rpm 99% of my driving. 1% 5k to 6k.
I could probably count on my fingers and toes how many times I have ever seen over 6.5k.

More TQ from 2k to 5.5k is still a pretty wide range.

But this idea/concept is not for everyone. I just like using/feeling boost all the time and not just when i wind it out, 9k that's impressive. But then again I'm an old fart.

Well fair enough.

However I do have doubt whether the Supercharger will work well with mid-range usability in mind as by design, boost level on the Vortech SC raise somewhat in linear or almost slight parabolic fashion and pulley size will not change that; you will always make max boost at red line and much less in mid-range compared to turbo or root-type supercharger, doesn't sound well when mated with automatic gearbox?

Also... I can't be the only one who thinks N54/55's character is right up your alley?

[CobraMarty]

Originally Posted by Kubricks

Also... I can't be the only one who thinks N54/55's character is right up your alley?

Where's the fun in that. We like the 'Built not bought' philosophy.

We have 2- '07 328xi, my son a coupe 5 speed, me a sedan auto.
We like the stealth sleeper approach.

Yeah it will be the same centrifugal SC boost curve. Same max boost psi just at 6k instead of 7k. This will shift the whole boost curve to the left and increase boost 1-2psi in the lower rpm area.

Do we have a documented boost curve anywhere? 2k to 7k? Easy enough to do, just video boost gauge and tach.

[InControl]

I've had turbo cars before, I think SC work similar where the full boost engages at full throttle. You can rev all the way to redline w/out hitting Max boost at half throttle. If you want to avoid running at full boost above 6k why not just train your right foot. The benefit of running to redline once awhile is to help avoid carbon build up in the motor.

[Torgus]

Shifting early I think you will be slower vs winding out the gears. Gearing and all that stuff.

It is rare for a car to be faster shifting below red line. Unless there is a massive drop off of power in the higher rpms.

[rjahl]

Originally Posted by Torgus

Shifting early I think you will be slower vs winding out the gears. Gearing and all that stuff.

It is rare for a car to be faster shifting below red line. Unless there is a massive drop off of power in the higher rpms.

Not true, I think all the newer FI engines don't like to rev out to the "red line". Certainly not the N54, in stock trim the factory "snails" run out of air/boost right after peak power, around 5,900. The racers will all say to shift early, way before the 7,000 painted on the dash.

I'm in a loaner this week end, brand new 330i and that motor also falls off right after 6,000 but the red line is 7,000. Both of these cars feel dead after 6,000.

It's a tough balance getting boost quickly at low RPM without sacrificing top end power.

The loaner is a story in itself. I had a misfire and took to it the dealer to resolve while getting the oil changed, Still CPO. It's taken them days to figure it out. No codes but it sometimes coughed and bucked under heavy load. This seems like a common theme with the FI motors, coils don't seem to last in them.

[Kubricks]

Originally Posted by InControl

I've had turbo cars before, I think SC work similar where the full boost engages at full throttle. You can rev all the way to redline w/out hitting Max boost at half throttle. If you want to avoid running at full boost above 6k why not just train your right foot. The benefit of running to redline once awhile is to help avoid carbon build up in the motor.

That's not how supercharger works.
In short, the boost level is directly in proportion to the engine rpm NOT throttle position. Max boost is always achieved at red line.

Turbo is completely different.

[Kubricks]

Originally Posted by rjahl

Not true, I think all the newer FI engines don't like to rev out to the "red line". Certainly not the N54, in stock trim the factory "snails" run out of air/boost right after peak power, around 5,900. The racers will all say to shift early, way before the 7,000 painted on the dash.

I'm in a loaner this week end, brand new 330i and that motor also falls off right after 6,000 but the red line is 7,000. Both of these cars feel dead after 6,000.

It's a tough balance getting boost quickly at low RPM without sacrificing top end power.

The loaner is a story in itself. I had a misfire and took to it the dealer to resolve while getting the oil changed, Still CPO. It's taken them days to figure it out. No codes but it sometimes coughed and bucked under heavy load. This seems like a common theme with the FI motors, coils don't seem to last in them.

Vortech Supercharger doesn't work that way.
Boost level increase in proportion to engine rpm because the impeller is connected with the crank, hence max boost is at the highest rpm you can do on that engine, unless you have a blow off valve artificially limit boost level after a certain rpm.

As for the 330i you have which runs out of breath after 6000rpm, you have another 1000rpm to stretch because you can take advantage of gearing (sometimes it more optimal than shifting up depending on the torque curve and gear ratio difference), or you take that extra rpm for a particular corner.

[Torgus]

Originally Posted by rjahl

Not true, I think all the newer FI engines don't like to rev out to the "red line". Certainly not the N54, in stock trim the factory "snails" run out of air/boost right after peak power, around 5,900. The racers will all say to shift early, way before the 7,000 painted on the dash.

I'm in a loaner this week end, brand new 330i and that motor also falls off right after 6,000 but the red line is 7,000. Both of these cars feel dead after 6,000.

It's a tough balance getting boost quickly at low RPM without sacrificing top end power.

The loaner is a story in itself. I had a misfire and took to it the dealer to resolve while getting the oil changed, Still CPO. It's taken them days to figure it out. No codes but it sometimes coughed and bucked under heavy load. This seems like a common theme with the FI motors, coils don't seem to last in them.

What feels fast and what is faster can be two different things. Again, it is rare for a car to be faster by short shifting. But in some cases it does make sense.

5:50 if you want to skip but you'll miss the math and the interesting stuff:

https://www.youtube.com/watch?time_c...&v=zZBqb0ZJSwU

https://www.onpointdyno.com/making-p...dyno-timeline/

Once you maximize the engine’s torque, the only way to make more horsepower is to make that torque at a higher speed. Infact, you’ll often see race engines lower peak torque in exchange for rpm, which makes more horsepower. The loss of torque is then made up with through gearing.



Go get a dyno with your different pulley and lower RPM redline and we can do the math and see what makes the most sense.



N52 SC dyno:


N54 dyno:



As you can see with the N54 the TQ drops off a cliff. Not so on the N52 SC. Hence why I really don't believe it would make sense to short shift even with the different pulley and E85 or meth which would change the dyno plot.

Again if someone wants to guestimate the power of the dyno plot at various RPMs we can do the math and see. I could certainly be wrong and it might be a fun exercise.

[CobraMarty]

That's exactly my point.
Maximum boost is at 5.5psi at 7000rpm, at 6000rpm boost is only about 3.5psi.

If you use a smaller pulley and shift the boost curve you can get the same maximum boost of 5.5psi at 6000rpm. The additional boost at 6000rpm will add 2psi which will add about 12.5% more power.
Because the boost curve is fairly linear and rises with rpm, we would see an additional +2psi at every rpm. This will increase both power curves tq and hp by 12.5%.

So torque of 225-250 will become +12.5% to 253-281TQ.
and hp at 6000rpm of 270 will become +12.5% to 304HP.
Both more than the boost curve with maximum 5.5psi at 7000rpm.

Now you must limit it to 6000rpm because it you rev it higher, you will get 7-8psi which might bee too much without some sort of cooling.

[Torgus]

Originally Posted by CobraMarty

That's exactly my point.
Maximum boost is at 5.5psi at 7000rpm, at 6000rpm boost is only about 3.5psi.

If you use a smaller pulley and shift the boost curve you can get the same maximum boost of 5.5psi at 6000rpm. The additional boost at 6000rpm will add 2psi which will add about 12.5% more power.
Because the boost curve is fairly linear and rises with rpm, we would see an additional +2psi at every rpm. This will increase both power curves tq and hp by 12.5%.

So torque of 225-250 will become +12.5% to 253-281TQ.
and hp at 6000rpm of 270 will become +12.5% to 304HP.
Both more than the boost curve with maximum 5.5psi at 7000rpm.

Now you must limit it to 6000rpm because it you rev it higher, you will get 7-8psi which might bee too much without some sort of cooling.

I think you should get the pulley made asap and inject some meth. Rev it all the way out! Do you have a place to make the pulley?

The larger area under the curve the better! Would also be nice to have your boost come on earlier I am sure, especially as a DD. Even if you don't want to run meth, I highly suggest it, you could always just never let it wind out vs say asking bpc to lower the rev limiter(assuming they can)

Happy memorial day weekend to you all btw.


Edit: Does anyone know if the higher psi from 6-7k will really cause an issue and need e85 or meth for knock resistance? I ask as I wouldn't surprise me if ess was just massively conservative...

[CobraMarty]

A Vortech 6 rib SC pulley will work with a little modifications. Easier to tweak the wheel instead of building one.

[CobraMarty]

So if you used a smaller SC pulley and redline limit it to 6000rpm and size it so you still only make a maximum boost of 5.5psi but now at 6000rpm instead of 7000rpm.

This will add +2psi to boost curve or 12.5% more power across the whole hp and tq curves.

You will make 10-12.5% more hp and tq from 2k to 6k and more peak hp and tq than before but will be limited to 6k rpm.
Basically +20ft-lb more TQ across the whole curve. That' significant!

This is probable better suited to auto than to manual cars.

[atmosphericM]

6k RPM Redline.. I'd cry.

Then again, Auto.. I'd cry. =P

I just love how having a motor that isn't super adored or adopted by the aftermarket community forces us to think outside the box here so much lol.

[Taskmaster]

Noir, any updates dude?

[Noir]

Originally Posted by Taskmaster

Noir, any updates dude?

I need to get with Randall.
Really don't want to be speaking on the behalf of anyone, but from what I understand, the flex fuel deal isnt happening... Soooooooooooooooooooooo.....
Just gonna have to schedule for install and dyno.
Gonna order that catch can in the meantime.
Seriously considering that LSD in the classifieds.

[atmosphericM]

Originally Posted by Noir

Seriously considering that LSD in the classifieds.

Me too, kinda, but right when I joined here I saw a bunch of horror stories related to MFactory and "Syncrotech" or whatever, so I feel like I'm permanently afraid of their products/work. For that kind of cash, I want to feel 99% if not 100% confident in my purchase.

I'll probably run open forever, and then if I still have/love the car a few years down the line, and it seems like I'll keep her for a long time, I'll go with Diffsonline.

[Torgus]

Originally Posted by Noir

from what I understand, the flex fuel deal isnt happening... Soooooooooooooooooooooo.....

It took Motiv a year + to create it for the N54 which included modifying a ton of tables, the hardware is pretty simple from my understanding.

I was honestly a bit skeptical of it coming out for the N52 as I see little to no market for it and the leg work to make it work flawlessly on Motiv's behalf would be large. NA is also not their wheel house unless BPC was modifying the tables and just using the hardware boostbox. There is some cost associated with running full E85 and on an NA engine with very little to gain by running high concentrations of E85.

I'm sorry for you guys. Guess you just have to stick with meth(which is better for a number of reasons IMO)