That "heat soak" issue you mention certainly hasn't played out in the last few Corvettes and Cadillacs that are running factory roots style blowers.

For road courses or 20-30min track sessions? Is this the new LS9 motor you're talking about?

LS9 or LSA -- either one.

Ya, won't be going with one of those motors though heh

I've had three Procharged builds, none of them had any lag. Instant boost on WOT, maybe not max boost immediately, but enough to blow the tires off. Definitely not laggy like a turbo setup with the wrong or improperly sized turbo would have. And far less heat management issues than a front mounted turbo setup. Personally, I'm sold on the roots type blowers now for true instant boost and driveability. They may not make as much HP as turbos, but far easier to package and maintain, far less heat issues to deal with.

Camcojb you say less heat to maintain in a roots style, how so? Everything I read says otherwise. They sit on top the motor and heat soak, from the drag strip to dyno pulls and for sure road courses. Have things changed recently? I'm not saying you're wrong just lookin for info!

Turbo heat can be dealt with decently easy. From what I've seen a roots style charger is harder to ditch the heat.

Oh and yeah, not to worried about raw hp numbers, more FUN and drivable for both street and some track days!

**Some sexy engine bays in your sig link!!**

Not talking heat soak, talking heat management. A front mounted turbo(s) will give you more heat management issues than any blower, at least they always have with mine. Air temps can suffer with a roots blower vs a turbo, but a good intercooler/heat exchanger/pump setup with a cool air intake source can improve that a lot. Under hood temps, oil temps, and even water temps are more of an issue with turbos than blowers in my experience. You've got all that extra exhaust plumbing as well as the turbo housings adding heat. The engine oil is further heated by going through the turbos, and water also if they're liquid cooled. Plus the intercoolers for turbos are usually much larger and thicker than the heat exchangers for a blower, so they affect the radiator airflow and cooling. Yes, they can be engineered to work with all of this, but to me the blowers are easier to deal with, have fewer heat management issues to address, and easier to bolts on (less fabbing). Doesn't mean that I don't like turbos, because I do. Plus after riding in "Mayhem" I just think that combo on the street or track is more than enough for pretty much anyone, even a guy like me that's had 1000 HP setups before.

You should go through the Mayhem build thread. Mark and I believe Brian Thompson, who built the engine, really give a lot of great info on heat management with the roots style blowers.

Maybe lag was the wrong term to use when talking about the Pro-charger but it's not as quick as a roots blower. I much preferred driving a Magnacharged vette to the Pro-charged ones even though the Pro-charged ones made more peak power typically. The torque band on a roots style blower is a lot better for street driving too. That's what really sells it for me.

I agree. :thumbsup:

Any boosted combination will have heat management issues to overcome whether it be under hood air temps with a turbo or intake air with a blower.
The problem with the roots type blowers available is the intercooler under the blowers don't allow enough water flow to efficiently keep up with the temperature rise running lap after lap on a road course. We've been doing some dyno testing with all the popular roots blowers out there and the only one we've found that has promise is the 4.0 whipple but even that one needs mods to the water fittings to allow it to pass enough water through it.
The 4.0 has a different set of problems, mainly the overall length with the drive and air intake makes it difficult to package in most cars. We've also found that even a 102mm throttle body is choking this blower and still shows vacuum behind the throttle blade. We are currently working on a shorter drive and air intake that uses twin 90mm throttle bodies that should cure that. The dyno mule made 962 hp with a 2.9L whipple but heat soaked badly, so we think we should be able to do the same with the 4.0L without all the heat soak since we can spin the blower slower and it has a better intercooler.

With all that being said, I don't understand why so many people concentrate on all these big peak power numbers when a higher average power number and a car with properly matched trans/rearend gearing will be faster.
My car was almost a full second faster than DSE's 70 camaro at LS Fest on the drag strip, same car, same track, same gearing and I'm giving up nearly 100 hp at the crank but because I built the engine to maximize it's power with that combination it's significantly faster.