Effects on Boost from better flowing heads

[Diabolic]

Hypothetical scenario

351 with TW170 heads, small cam, GT40 intake
Vortech S Trim

Makes 9#'s at 5000 rpm and 450hp

Swap TW170 heads with AFR 225's
Same combo, same S-Trim, same pulleys

Now it makes only 6#'s at 5000 rpm due to the heads

Would you still hit 450hp at 5000 rpm, just with less boost and less detonation or would the engine far exceed the 450 hp mark made with the smaller heads and higher boost number?

[Cooter]

depending on where you were in the efficiency map it may make more power

[Doug Hatton]

Boost is really just backpressure on the inlet side. Same pulley, less boost means it's eating that boost up with less backpressure. Hard to say if it'd make more or less power, but I'd guess the same or more since it's technically taking in more air.

[Diabolic]

I came across a really good deal on a used BD11 Powerdyne for my 93 Lightning. Thise kits are near impossible to find so I couldn't pass it up. My neighbor also has a 93 Lightning that is bone stock. He does a lot of side jobs on my rental properties so I figured it could go to him in trade in a few months. I already have a Vortch setup on the truck awaiting a head unit. I figure until then I could bolt on this PD head unit since it's self contained. I had one on the truck previously and saw 7-8#'s of boost when it was bone stock. Now I have AFR heads, longtubes, O/R exhaust, 70mm race tb, etc...... Figure I may only see 4-5#'s of boost but I was hoping to see a 75+hp improvement. I already spray a 100-150 shot on the truck and have those tunes dialed in nicely. I'm going to add the PD, and spray it out of the hole through 2nd gear. Hoping it will be pretty fun until I can get my hands on a T-Trim head unit.

[RuStYpNuS]

I came across a really good deal on a used BD11 Powerdyne for my 93 Lightning. Thise kits are near impossible to find so I couldn't pass it up. My neighbor also has a 93 Lightning that is bone stock. He does a lot of side jobs on my rental properties so I figured it could go to him in trade in a few months. I already have a Vortch setup on the truck awaiting a head unit. I figure until then I could bolt on this PD head unit since it's self contained. I had one on the truck previously and saw 7-8#'s of boost when it was bone stock. Now I have AFR heads, longtubes, O/R exhaust, 70mm race tb, etc...... Figure I may only see 4-5#'s of boost but I was hoping to see a 75+hp improvement. I already spray a 100-150 shot on the truck and have those tunes dialed in nicely. I'm going to add the PD, and spray it out of the hole through 2nd gear. Hoping it will be pretty fun until I can get my hands on a T-Trim head unit.

wait i thought i was in line......or am i the neighbor

[turbos66coupe]

wait i thought i was in line......or am i the neighbor

Hahahahaha...damn


You will likely still see 6lbs to 7lbs of boost with the bd11a on that 351. Last 302 I built with one of those on it had vic jr heads (210cc) and intake combo still saw 6-7 lbs. Buy a few extra belts for that headunit .

[DON SVO]

boost is a measure of resistance, it is not airflow. Since it is a supercharger, airflow is going to be fixed and dependent on impellar speed (pulley size). With better heads, your car will still see the same amount of airflow but at lower boost levels. This will typically translate into more power also, since pressurized air is also heated air... if you can move 42 lb/min @ 7psi instead of 9psi, it stands to reason you might make more peak hp.