Pumpkinodin8844

Looking for any input in order to make sure I'm educated before accepting my dyno results. Mods added include Magnuson supercharger with secondary Z06 drive, upgrade to 70mm pulley, LT4 fuel pump and injectors, haltech stinger air intake and finally kooks 2 inch long tube headers with green catted xpipe. After tune only getting 515rwhp and the boost hits 9psi and the drops to 5.5 psi. Shop vacuum test for boost leaks, double checked bypass valve checked for belt slip. The shop is going to consult with the place I bought the items from to see what the suggest . Current speculation is the free flowing exhaust may be the issue or need even a smaller pulley to get the boost up. The issue is I should have gotten 515rwhp with just adding the basic magnuson and so all the other upgrades appear to be for nothing.

Live just above sea level in central Canada

BlueDevilZ51

Do you live at a high altitude? Those numbers seem really low, even if the only mod was your blower. I've seen stage 2 Edelbrock e forces like I have on my car make high 500s with no other mods, but that was at sea level.

Pumpkinodin8844

No I live in central canada so elevation is just above 200 meters. I've also heard similar results with many people reporting closer to 580 rwhp and I'm really hoping that my local shop can get to the bottom of it but I figure I would be proactive and see if I can come to them with some suggestions as well.

FYREANT

Who is the tuner? Sounds like they have no clue how to tune this car. The E92 ECM is a major change from the LS motors. Sounds like you should get your money back and go to someone who knows what they are doing..

Ant

Pumpkinodin8844

I don't want to say yet as they are working on it so if it's fixed all is good. I can tell you there well known so you might be surprised if they can't fix it.

FYREANT

Fair enough. Keep us posted!

Fore58

Good question

C7&7

Boost is dropping cause the throttle is closing. It's the tune. Ant is right.

Pumpkinodin8844

Nope live just bove sea level in central Canada

robert miller

with this & Ant with no boost leak in the tune. These cars are totally diff than the LS set up. Robert

davepl

Always cracks me up that Eastern Canada calls itself "Central". Saskatchewan is central!

Anyway, I'm almost morally certain it's one of two things:

a) Belt slip, or
b) Torque demand tables now being exceeded by actual torque production so the TB is closing to bring power down to the table's value

I've seen this in person on an NA motor, watched the blades do it on the dyno.

[Edit: I see a couple of people already said this, so just consider mine a vote for theirs!]

Pumpkinodin8844

Actually in Manitoba so it's pretty central lol

davepl

Central enough for me! I was thinking of when people call Toronto "central Canada" :-)

Bad Jake28

just out of curiosity at what RPM did the car stop making power?

2highpsi

Whoa! Did you say LT1 with Z06 drive and Maggie 2300?

Who suggested that pulley? Is this on pump gas?

Stock pulley for the kit with dedicated drive is 98mm which delivers 6.5-7 psi. Other options are as follows:

95mm - about 7.5 psi - Max for pump gas.
90mm - about 8.5 psi - Max for stock fuel system and good gas.
80mm - about 12 psi
75mm - about 14 psi
70mm - about 16 psi

I don't know what octane fuel you're using or what fuel system you're using but it had better be serious.
I'm running a 75mm on a 6th gen Camaro which makes 730RWHP and just ran a 9.93@140MPH.

Hopefully the throttle didn't open, other wise you might have a more serious issue with your engine.

Pumpkinodin8844

Two updates:

1. Got a new tuner so hopefully that helps

2. Turns out the shop I used for install is using dyno dynamic vs dynojet. My understanding is the dynojet leans toward a higher value so much that on average dyno dynamics aka the heart breaker is 13% lower. So 515 rwhp is 590rwhp on the dynojet.

Soto2424

So was the problem the tuner? I’m having the same problem where I’m only making around 4psi on a 8psi pulley.

Pumpkinodin8844

I got it all worked out. Main issue was the tune. New tuner did there thing and I went from 5 psi to 14 psi which was way to much for the Lt1 so I then moved to a 85mm pulley bringing it to 9psi. On top of that i was experiencing misfiring which was a result of bad plugs and wires and coil pack. Once I got this fixed my cats starting acting up so I went cattless. Now on the dyno I'm 640rwhp 9psi and it runs great. My advice is pay the $$$ and find a good reputable company. In Canada I ended up using Davenport but if I was in the USA my choice would be a place like lingenfelter and I'm pretty sure they offer remote tuning. Costs a bit more but I wasted 1500 on a bad tune.

Avanti

Boost is going "somewhere," not mixing with fuel in the engine. I've used turbos and assorted superchargers, and If the boost is falling off at higher rpms, something is wrong... little boost = little powers.

Higgs Boson

the ecm closes the throttle based on torque output