Larger turbos have the ability to run more efficiently for the same boost pressure compared to smaller turbos, resulting in cooler, denser air (more air mass) and thus more power. You have a ways to go before you start moving out of the highest efficiency islands for your set up. Most turbo set ups can make power at the 400 whp level all the way to redline. Regardless of turbo specs, there is a point where the intake system can only feed so much mass air per unit time and the cylinders require more as power levels rise. You will reach that point later with larger turbos (that are pushing out denser air), but that point exists for everyone and every setup.

So a more relevant title/topic for this thread would have been, show me a setup that makes power above 6700 rpms above 600 whp, for example. You can imagine that at the 400 whp level it's not an issue. At 700? Above that? I don't think even the almighty Cosworth could have saved the high rpm plummetting torque line on IP's green monster as it passed the 1000 whp level.

 

Very well said! That is exactly what i was thinking, but you summarized better than i could

 

That also depends on which turbos you are using to make 650WHP.If you are using twin 18G's with super tiny hotsides then it will be very hard. But if you are using a pair of 61mm turbos with .82 AR exhaust housings then it is alot easier to make the power keep climbing.With less backpressure, you can run more timing,have lower charge air temps with the big compressors,etc.......

 

The factory ECU is controlling both throttlebodies and both MAF sensors.

 

Wow, that is extremely impressive. I presume that for someone is running a greddy tt, they would also need the 2-in 2-out intercooler too.

 

Yes sir.Unless you want to get into a plumbing nightmare

 

valve float is when you don't have enough spring pressure to control the valves...this is usually due to rpm, but can also happen due to radical cam profiles. No one has really radical ramps on their cams for the VQ, so that's not as much an issue as rpm is.

if you try to push 7500 on stock valve springs, you will "float" the valves. the stock springs are so soft that at 7500 rpms, th cam is spinning so fast that when the ramp part of the lobe comes in contact with the lifter (bucket), it basically slams the valve open to the point where the valve isn't in contact with the cam. conversely, the same can happen on the closing ramp of the cam too. at higher rpms, the cam is mocing so quickly that as the valve is literally floating because the cam ramp moved away from the valve faster than the spring can keep the valve in contact with the cam ramp.

 

I would think by the content of my post you would observe that I know what valve float is...

 

Not true, forcefed on here is spinning stock heads/valvetrain (other than bc stg 2 cams) to 8200rpm's...