Kraftwerks Supercharger Owners Thread

[zoth]

Originally Posted by Derka

I took my belt off. And the noise went away

Pulley noise, then. Typical for the system. Well at least on mine. With my N1 does not bother me that much. Just remember there will be additional noise vs. stock, no way around that.

[Derka]

Yea I get that. But this is a really loud rattle. Not just added noise. It's hard to describe. But it's a rattle more than just pulley noise.

[86SPEED]

Originally Posted by Derka

Yea I get that. But this is a really loud rattle. Not just added noise. It's hard to describe. But it's a rattle more than just pulley noise.

My first time installing, i didnt have my belt set tight enough, and got belt slap, some times a sound that i could actually feel with my feet on the floor board. For my situation, when i saw the KW guys at 86 Fest, he knew exactly what mine was and it was belt slap, it cleaned off the anodizing off the lower plate mount from slapping it, once i tightened it that noise went away, but the 1500rpm noise was still there, and when that belt finally snapped from all the belt slap, my noise was still there at 1500rpm when cold..

-Thomas

[Derka]

What is your tension set up at now? Would you mind getting a measurement?

[Sellout]

Originally Posted by SPCorBUST

Better powerband? How so?

Just the physics of how the impeller builds boost, the speeds involved, etc. The larger impeller running a lower speed to keep the power down in the 300whp range will result in the boost curve being less linear and more exponential (very slightly) think of the powerband difference between the vortech and the C30 at roughly the same peak power... This is a large part of why there are so many different sizes for superchargers. If you run a 900hp supercharger at 300hp, your powerband is smaller than the next guy who is running a 400hp supercharger at 300hp. The actual friction losses from the larger blower are not big enough to explain the powerband differences, and would likely be offset by the MUCH cooler charge air. You're also only moving 300hp worth of air, so the larger blower doesn't take more of your power aside from the very small friction difference, but the longer boost ramp up time would be painful in comparison

[SPCorBUST]

Originally Posted by Sellout

Just the physics of how the impeller builds boost, the speeds involved, etc. The larger impeller running a lower speed to keep the power down in the 300whp range will result in the boost curve being less linear and more exponential (very slightly) think of the powerband difference between the vortech and the C30 at roughly the same peak power... This is a large part of why there are so many different sizes for superchargers. If you run a 900hp supercharger at 300hp, your powerband is smaller than the next guy who is running a 400hp supercharger at 300hp. The actual friction losses from the larger blower are not big enough to explain the powerband differences, and would likely be offset by the MUCH cooler charge air. You're also only moving 300hp worth of air, so the larger blower doesn't take more of your power aside from the very small friction difference, but the longer boost ramp up time would be painful in comparison

That doesn't sound right at all, but I'm no expert. If we simply overlay a stock car with C30 against C38 my guess is you start at basically the same point but afterwards hit higher numbers (rpm to rpm) in the C38 across the board, widening the distance between the two the higher you go in rpms, like a steeper incline. How is that less power in the power band? It would be making 300hp much faster. If he wanted to cap 300hp and never run more than that, then he'd essentially have to cut 1k rpm off of his rev limit since you're reaching the hp goal so much sooner. But maybe KW or CSG Mike can lay some actual facts/experience down versus what seems like conjecture from the two of us.

[Calum]

Originally Posted by vgi

I noticed that in cold weather the belt for some reason seems to have more slap (which is kind of counter intuitive, usually materials stretch when hot). I checked it several times when leaving from parking and it seemed lose, checked it again home after about 20 mins of driving and it seemed ok. So not sure if it's just mine or a common behavior, if the latter then it could explain the noise somewhat.

It could be the pulleys shrinking and expanding with the temperature.

[Sellout]

Originally Posted by SPCorBUST

That doesn't sound right at all, but I'm no expert. If we simply overlay a stock car with C30 against C38 my guess is you start at basically the same point but afterwards hit higher numbers (rpm to rpm) in the C38 across the board, widening the distance between the two the higher you go in rpms, like a steeper incline. How is that less power in the power band? It would be making 300hp much faster. If he wanted to cap 300hp and never run more than that, then he'd essentially have to cut 1k rpm off of his rev limit since you're reaching the hp goal so much sooner. But maybe KW or CSG Mike can lay some actual facts/experience down versus what seems like conjecture from the two of us.

This may be conjecture, but it's conjecture that comes from every supercharger kit manufacturer I've ever been able to discuss this exact issue with. This is what you'll hear if you ask a Vortech rep why they make so many different head units. Or why they can't just take the S-Trim and make it the go-to head unit for every street supercharger kit. It's big enough for all of them, so why not use it? This is the reasoning we got from KW back in the days when Oscar Jackson was involved with them and we were trying to get them to use the larger C38 in their S2000 supercharger kit.

That turned out to be a bad example, and I do remember making a smartass comment about how the dyno chart from the larger head unit was not lower in power than the C30 anywhere on the dyno chart. But we were comparing a C38 running the power number you should be looking for from a C38, not a C38 that's hampered by a large pulley to keep the boost down so you can run ONLY 300 hp.

And nobody is going to cut their rev limit down to less than stock just because they've got a low power goal. I would do it to avoid swapping pulleys between a pump and e-85 tune, but if you're only trying to hit 300whp on E85, you're going to be running a low boost pulley on the C38 to do so, which is exactly why the C30 will be a better choice.

[enivid]

Originally Posted by SPCorBUST

That doesn't sound right at all, but I'm no expert. If we simply overlay a stock car with C30 against C38 my guess is you start at basically the same point but afterwards hit higher numbers (rpm to rpm) in the C38 across the board, widening the distance between the two the higher you go in rpms, like a steeper incline. How is that less power in the power band? It would be making 300hp much faster. If he wanted to cap 300hp and never run more than that, then he'd essentially have to cut 1k rpm off of his rev limit since you're reaching the hp goal so much sooner. But maybe KW or CSG Mike can lay some actual facts/experience down versus what seems like conjecture from the two of us.

I saw a C38 Dyno making 300whp. Pure lag compared to the C30 making 280whp. Not worth it. Get a turbo if you want all that lag.

[DAN_BRZ]

add me to the owners list, just purchased my kit from @rickspecd
awesome guy to deal with. if anyone is looking for a good deal on this kit i suggest contacting him... now come on nicer weather!!!!!!!

[CSG Mike]

Originally Posted by Sellout

This may be conjecture, but it's conjecture that comes from every supercharger kit manufacturer I've ever been able to discuss this exact issue with. This is what you'll hear if you ask a Vortech rep why they make so many different head units. Or why they can't just take the S-Trim and make it the go-to head unit for every street supercharger kit. It's big enough for all of them, so why not use it? This is the reasoning we got from KW back in the days when Oscar Jackson was involved with them and we were trying to get them to use the larger C38 in their S2000 supercharger kit.

That turned out to be a bad example, and I do remember making a smartass comment about how the dyno chart from the larger head unit was not lower in power than the C30 anywhere on the dyno chart. But we were comparing a C38 running the power number you should be looking for from a C38, not a C38 that's hampered by a large pulley to keep the boost down so you can run ONLY 300 hp.

And nobody is going to cut their rev limit down to less than stock just because they've got a low power goal. I would do it to avoid swapping pulleys between a pump and e-85 tune, but if you're only trying to hit 300whp on E85, you're going to be running a low boost pulley on the C38 to do so, which is exactly why the C30 will be a better choice.

If only you knew how much shit I gave Oscar Jr back in the day...

[KraftWerks]

Originally Posted by enivid

I saw a C38 Dyno making 300whp. Pure lag compared to the C30 making 280whp. Not worth it. Get a turbo if you want all that lag.

Simply on the question of lag, here is this:



This was our BRZ with header and exhaust.
The only thing changed was the Head Unit itself between the C30-94 and C38-81. The same pulley combination was used for both chargers.

The top shows the power/torque curve with the C38 above throughout the entire graph. The bottom shows what the boost was doing with reference to again, the C38 was producing more and each given RPM point which was to be expected.

If you're ONLY looking for 275whp, then you should stick with the C30. Even then, you still have the option to upgrade the pulley size as well as add E85, etc. for more performance. If you're looking for 300 and beyond, easily, then the C38 is the better option of the two. Even with the base set of pulleys you will not be disappointed. Once you've become comfortable with that power, you always have the option to upgrade the pulley, fueling, etc. for even more. There are a few already above 400hp as of right now which is not pushing the C38s to their limit by any means.

[SPCorBUST]

If I'm reading that correctly, I think it confirms what I was saying about power across the board being higher with the C38. If not, they would cross somewhere. I'm pretty sure that with the high boost pulley and e85 the differences would be even higher.

[86SPEED]

Originally Posted by Derka

What is your tension set up at now? Would you mind getting a measurement?

I could measure mine, but im not running a regular set of high boost pulleys. Im running a slightly smaller blower pulley. my setup i couldn't even put the lock nut on the tension bolt. i set tension, tightened the pulley, then snugged the bolt against the bracket. I just haven't ran down and picked up a longer bolt yet since this has worked just fine.

-Thomas