Opinions on pulley gains

[SecondZ28]

So obviously we have a well known vendor that has a 75whp kit that is a 10% lower, CAI, and handheld tune.

Since they are not nearby, I went to my local (but well known) LS shop. They quoted me a 70-80whp gain with a 26% upper (2.4"), CAI, Id1050 injectors, BAP and dyno tune.

What am I missing here? Shouldn't a 26% overdrive with fuel enhancements give more than that? How are they quoting the same gains?

Also, is it worth it to do the upper just to replace the spring with the solid isolator? Will this avoid future failure?

[ZMEnow]

I think you answered your own question. It’s all in the tune and apparently they don’t have it. Call Ted....

[Can'tHave2MuchHP]

I think two things are at play there...There's a lot in the tune and a 75 RWHP gain is pushing it on a 10%/Intake setup. I would EXPECT 50 RWHP from a 75 Kit but regularly see 60+ on most cars. A 2.4"/Fueling/Intake would likely benefit big time (30-40 HP+) from Headers at that point which would be your missing part IMO.

[ZMEnow]

Originally Posted by Can'tHave2MuchHP

I think two things are at play there...There's a lot in the tune and a 75 RWHP gain is pushing it on a 10%/Intake setup. I would EXPECT 50 RWHP from a 75 Kit but regularly see 60+ on most cars. A 2.4"/Fueling/Intake would likely benefit big time (30-40 HP+) from Headers at that point which would be your missing part IMO.

My remote tune from JRE with the 75kit dyno’d right at 581 with a base of 505 when I started years ago...

[SecondZ28]

Originally Posted by ZMEnow

My remote tune from JRE with the 75kit dyno’d right at 581 with a base of 505 when I started years ago...

Are you able to log with the handheld to see what your duty cycle is at?

[ZMEnow]

Originally Posted by SecondZ28

Are you able to log with the handheld to see what your duty cycle is at?

It was quite a few years ago as I upgraded, but they never exceeded 80%.

[SecondZ28]

It's hard to believe they are leaving that much on the table, because they are also well known for LS work.

What about doing the upper instead of lower, in order to install the solid isolator?

[crazydave]

Originally Posted by SecondZ28

It's hard to believe they are leaving that much on the table, because they are also well known for LS work.

What about doing the upper instead of lower, in order to install the solid isolator?

Pulleys have diminishing returns without supporting mods. Upping the boost just creates heat, heat creates detonation and requires that timing be pulled or fuel to be added to compensate. There is really no reason to go any higher than an 18% overdrive unless you are doing headers, or adding octane. At that point you need to start thinking about diminishing fuel pressure. As stated on this site many times dynos are just tuning tools and cannot really be aaccurately compated to one another. 1/4 Mile trap speed in like DAs is where you should look for gains. The shops estimate is pretty reasonable for rwhp. If they have exerience with LSAs and have a long history of quailty work you could go with then. There are plenty of good LS tuners in the country...but also some bad ones, so do your research.

[Can'tHave2MuchHP]

OP, by chance are you speaking of Speed Inc?

[hammdo]

Originally Posted by crazydave

Pulleys have diminishing returns without supporting mods. Upping the boost just creates heat, heat creates detonation and requires that timing be pulled or fuel to be added to compensate. There is really no reason to go any higher than an 18% overdrive unless you are doing headers, or adding octane. At that point you need to start thinking about diminishing fuel pressure. As stated on this site many times dynos are just tuning tools and cannot really be aaccurately compated to one another. 1/4 Mile trap speed in like DAs is where you should look for gains. The shops estimate is pretty reasonable for rwhp. If they have exerience with LSAs and have a long history of quailty work you could go with then. There are plenty of good LS tuners in the country...but also some bad ones, so do your research.

This is so true. I used the dyno to measure what my changes are doing — and how it will perform in the real world — no `glory’ runs. Since I road course my car, I need to know how it handles the heat, thus we heat soak the blower and run the dyno — at the same place (in my case Ryan @ GPI).

Great advice right there crazydave!

-Don

[Can'tHave2MuchHP]

Speed Inc knows what they’re doing. Take it to them and don’t worry about a thing. They built my buddies ZR1 and they always give conservative numbers but their cars rip. I would definitely do Headers though.

[ZL1 TIBS]

I picked up 70 RWHP with a 10% lower, CAI, LT headers, injectors and a tune from a well respected local tuner. We actually picked up 75 on one run, but he backed things off a tad since it is my daily driver.

[SecondZ28]

The pump voltage booster at minimum is required for any ZL1 getting a pulley upgrade.

Shop said this, but I haven't read much the need for it on here for mild pullies?

Not sure about headers at this time, I would like a stock appearing car. Which is why I would prefer to do a lower pulley, but I keep reading about the spring loaded upper as a timebomb. Do I wait for the marbles sound and get the warranty to replace it? Or take care of it now with the solid isolator mount?

[Can'tHave2MuchHP]

Originally Posted by SecondZ28

Shop said this, but I haven't read much the need for it on here for mild pullies?

Not sure about headers at this time, I would like a stock appearing car. Which is why I would prefer to do a lower pulley, but I keep reading about the spring loaded upper as a timebomb. Do I wait for the marbles sound and get the warranty to replace it? Or take care of it now with the solid isolator mount?

It’s not necessary below 18%. After that in order to get enough fuel/PSI got proper atomization you’ll want a Pump Voltage Booster (BAP is usually what it’s referred to here).

Headers are going to be very beneficial for HP, pressure relief, temps etc. I’d go as far as saying they are necessary at anything over 18% OD. Stock appearance shouldn’t be too bad of a problem, I mean anyone who is going to recognize headers will recognize the intake and pulley/belt that’s not OEM either.

You can do the lower but it’s more expensive in parts and you won’t get to do the isolator. There’s a long warranty on the supercharger to cover specifically the isolator but I would think most dealers would tell you to walk if you’re full bolt on and asking for a free fix.