Unlimited jd

iTrader: (5)

Hey Brad, I was speaking of the drag race 3500+ hp stuff. 140mm compressors
And yes none of that would work in a boat. I’m not a fan of centrifugal blowers in boats. No offense on your setup.

speicher lane

I came across a listing in Bobcaygeon, Ontario ( yes, the town from The Tragically Hip song), but the price with the drives is enough to make buying new a realistic consideration @ 185 hours on them.

https://www.birchpointmarina.com/inv...-1a0-11196820i

Jpzaluski

Thank you. I’ll give them a ring. I’m just looking for a single motor.

hustlerguy

15 hrs since rebuild at that price is not a terrible price

hustlerguy

Comparing a drag race car with a turbo or a supercharger is not nearly the same thing as a boat. When does a boat only run wide open for 7-9 seconds? A turbo motor in a long pull like 3-6 minutes makes reliable HP compared to a supercharger.
Why do cars and trucks from modern manufacturers use Turbos? Because they work to make great power and reliable power.
I dont know a single person who owns or has owned a QC4v motor who says man I wish I had some old school blower motors instead of these nice and reliable, good idling and docking motors with wicked power and torque when you push the throttles forward.

IGetWet

The way it reads to me the drives have only been rebuilt with 15hrs on them. The motors are still at 185.

Brad Christy

Unlimited,

No offence taken. I'm not a fan, either. When we were in prospect to buy our PQ with the ProCharged 496HO, I was all excited to potentially be buying a supercharged boat, as that is what I grew up skiing behind. After owning it for a couple years, while I still LOVE the boat, and it runs pretty well (after getting the injectors sorted out), I have come to the conclusion that there just is no substitute for a positive displacement supercharger for marine application, for which neither turbos nor centrifugal qualify. If we get to a point need to rebuild our 496, I will be selling the ProCharger, replacing the cast pistons and going with a Whipple.

Thanks. Brad.
(937)545-8991

IGetWet

You obviously have not ridden in a boat powered by, or even talked to a real owner of QC4V‘s.

Just getting away from the archaic pushrod valve train is a huge step up.

Brad Christy

Hustler,

Car and truck MFRs.... They don't "use turbos", as a matter of default. It's split down the middle with a relatively even number of both turbos and superchargers, with literally ALL of the mainstream MFRs "performance" offerings being supercharged. The only time turbos are really of any value is when sustained high RPM is the soup du jour. The top end Corvettes and Mustangs all hum along at 80MPH at 1500 RPM because they are supercharged and produce usable torque at that RPM, allowing for gearing that will sustainably yield that speed. It's pretty much the same story with marine engines. As I've observed, supercharged boats run faster, by in large, because they have the low end torque to pull bigger props getting on plane. For the most part, we don't have transmissions that we can shift into a higher gear once we get on plane. This makes planing torque the limiting factor for prop size selection. This is why Merc has abandoned the superchargers, in lieu of turbos: they are not concerned about planing time. It's also why we have prescribed planing procedures on these boats, with vent tubes, tabs and drive trim being necessary functions of getting these larger boats on plane.

Thanks. Brad.
(937)545-8991

Brad Christy

IGetWet,

I'm not knocking the QC4V at all, and I wholly agree with the valve train aspect. It's really all about where we want the torque curve to be, and where we want the top end to be. I guess I've answered my own question as to why Merc went with turbos. It's easier to build a production engine at that HP level. But we don't see anybody building custom engines with turbos. Not even for the 50 footers. And those engines are in faster boats.

Thanks. Brad.
(937)545-8991