Smaller pulley but very short coming results???

[Velocity10gear]

So I have a vortech v7 ysi 8 rib kit on my '20 gt pp1. its running a 3.25 griptec pulley and the current engine mods are MMR Billet Oil Pump Gears and crank sprocket as well as NGK 6510 spark plugs. ID1050x injectors and a Sai Li fuel system. On the stock 3.6 vortech pulley and an e85 Lund tune it put down 778hp to the wheel. Now, after installing the 3.25 griptec pulley, it put down 808hp. I recently had codes thrown to change the upstream and downstream driver side O2 sensors, and i dyno'd the 808hp while still having that issue. It was recommended that I change those sensors before sending data logs to Lund, since they deal with fueling. I changed those and now there are no codes. I still plan on sending data logs to lund, but does anyone have any idea of what is causing the lack of power? My builder even mentioned that those were pretty low numbers considering i should be building about 16-18psi boost with the current pulley. Im just a bit confused and bummed out. Looking to see what the issue is

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[ice445]

Do you have factory cats? They're probably pretty unhappy at this point if you're making that much power. Even aftermarkets won't like it. At the very least they may be restricting exhaust flow enough to limit power.

Also, I hope your A10 is built if you're trying to go past 900

 

[Velocity10gear]

Do you have factory cats? They're probably pretty unhappy at this point if you're making that much power. Even aftermarkets won't like it. At the very least they may be restricting exhaust flow enough to limit power.

Also, I hope your A10 is built if you're trying to go past 900

No cats. Full corsa exhaust system. Headers & catback exhuast, x pipe. Any other ideas as to what could be the issue?

 

[ice445]

No cats. Full corsa exhaust system. Headers & catback exhuast, x pipe. Any other ideas as to what could be the issue?

Belt slip or mixture control issues from the tune maybe. What's your spark plug gap set to?

 

[Velocity10gear]

What would be a tell sign of belt slip? and with mixture controls im assuming that's something that'd only show through the data logs? & i have no idea what the current plugs are gapped to. Could you explain how this could also be a reason please?

 

[Cory S]

Do you have factory cats? They're probably pretty unhappy at this point if you're making that much power. Even aftermarkets won't like it. At the very least they may be restricting exhaust flow enough to limit power.

Also, I hope your A10 is built if you're trying to go past 900

10R80 needs upgraded clutches even above 750whp/600tq

 

[LOL WUT]

What would be a tell sign of belt slip? and with mixture controls im assuming that's something that'd only show through the data logs? & i have no idea what the current plugs are gapped to. Could you explain how this could also be a reason please?

With belt slip you’d see a decent amount of rubber belt dust around the supercharger pulley. You should also be able to see it via a log with boost falling off in areas where it typically shouldn’t.

Regarding your plugs, if they are gapped too large, you could be experiencing spark blow out but I believe that’s quite noticeable during a pull with it feeling as if power is being cut off at times.

 

[Velocity10gear]

10R80 needs upgraded clutches even above 750whp/600tq

I agree. They’re upgraded though. I have a SunCoast stage 2 trans rebuild kit on it

 

[Velocity10gear]

With belt slip you’d see a decent amount of rubber belt dust around the supercharger pulley. You should also be able to see it via a log with boost falling off in areas where it typically shouldn’t.

Regarding your plugs, if they are gapped too large, you could be experiencing spark blow out but I believe that’s quite noticeable during a pull with it feeling as if power is being cut off at times.

Ok. Thank you for this. I’ll check for the belt dust and i guess I’ll send the data log in the midst of all this as well. Hoping this can clarify my confusion and solve the issue.

 

[Proshop]

How many psi did the stock 3.6 pulley produce?

 

[Velocity10gear]

How many psi did the stock 3.6 pulley produce?

About 11psi

 

[Proshop]

About 11psi

Ok so let’s play the numbers game all estimation of course…
Stock 400 whp, vortech 11 psi 778 : 778-400 =338 which equates to 31 whp per psi of boost. Now you stated it should be running 16-18 with the new 3.25 pulley. Was it confirmed it was running that much on the 2nd dyno? Let’s just say it hit 16 psi and we went with the calculations above you would in theory be at 891 whp.
My questions would be: Is it the same dyno, tires, conditions (temp) and DA? There is a lot that can be lost due to these things and it could ultimately be your o2’s we’re the issue also.

 

[Velocity10gear]

Ok so let’s play the numbers game all estimation of course…
Stock 400 whp, vortech 11 psi 778 : 778-400 =338 which equates to 31 whp per psi of boost. Now you stated it should be running 16-18 with the new 3.25 pulley. Was it confirmed it was running that much on the 2nd dyno? Let’s just say it hit 16 psi and we went with the calculations above you would in theory be at 891 whp.
My questions would be: Is it the same dyno, tires, conditions (temp) and DA? There is a lot that can be lost due to these things and it could ultimately be your o2’s we’re the issue also.

That’s actually a fair estimate of what myself and my builder were expecting, number wise. But to answer those questions, different dyno, I’m unsure of the weather during the previous dyno, same tires though. I also don’t know the boost psi that was output during these pulls. I’ll attach a picture of the screen from the dyno to this post

 

[Proshop]

That’s actually a fair estimate of what myself and my builder were expecting, number wise. But to answer those questions, different dyno, I’m unsure of the weather during the previous dyno, same tires though. I also don’t know the boost psi that was output during these pulls. I’ll attach a picture of the screen from the dyno to this post

That thing was pulling/ adding hp all the way to 8k so highly doubt it was belt slip or even pulling timing and fuel unless it was doing it the whole run. We’re both dyno’s dynojet? Did you log the dyno? Once again if the conditions (temp and DA) were different it will affect the numbers.
Just another calculation:

 

[MKL_DS]

You simply cant compare results from 2 different dynos on 2 different days.
If you had logs of runs on both dynos, some determinations could be made regarding increases in airflow, etc.

Right answer is to compare whatever your 778 rwhp trap speed was to what it traps now. Thats all that matters.

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