Supercharged v NA
03-06-2016, 08:50 PM
#71
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but that 320 hp engine will no doubt see 300 thousand miles.
03-06-2016, 08:52 PM
#72
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that,s some deep chit right their.
03-06-2016, 09:51 PM
#73
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Here's a real world example that I have experienced in the past....
I think it has to do a lot with how a boat is set up as well...drives, drive height, x-dem, nose cones, etc. I have said this before on here a few years back when I once owned a 32' AT....and my buddy owned a 32' AT. I had 565cid naturally aspirated engines that made about 615hp on Dave W's dyno with very mild hydraulic roller cams. My buddy had 557cid engines with some 871 roots style superchargers on them that supposedly made about 750+hp. He could not pull away from me at midrange at 3500rpm up with both of us at WOT.....and while at top RPM of 5600, he could still not pull away from me. We both had Bravo drives...I had XR's and he had another type of X...we both were running 1:5 gear ratios. I always had my fuel tanks topped off....while he was always looking for one of the gas docks to refuel his tanks.
That's 615hp vs 750+hp....we both turned the same RPM up on top @5600rpm. He would ask me to open my engine hatch and he would just stare at my engines for several minutes....probably trying to hopefully catch me red handed with finding a NOS hose and bottle somewhere. But I told him that it was probably the way my drives were set up on my boat.....extension boxes, -2" IMCO shortys with a nose cone integrated into the IMCO shorty...compared to my buddy's boat not having any of these things. It seemed to be as if it was worth another 300+hp on my boat compared to my friend's same boat....difficult to believe...I know, but we ran raced each other several times over on different days...we do our boating out of the same area.
All else remaining the same and CID for CID, etc, I would still find it very difficult to believe that an NA engine would outrun/perform a supercharged engine within the same RPM power band in the same hull, etc. And if it did, I would have to think it would be very rare...few and far between.
The other funny thing is that I eventually sold him my XR drives.....he said they slowed his boat down by about 2-mph.
I think it has to do a lot with how a boat is set up as well...drives, drive height, x-dem, nose cones, etc. I have said this before on here a few years back when I once owned a 32' AT....and my buddy owned a 32' AT. I had 565cid naturally aspirated engines that made about 615hp on Dave W's dyno with very mild hydraulic roller cams. My buddy had 557cid engines with some 871 roots style superchargers on them that supposedly made about 750+hp. He could not pull away from me at midrange at 3500rpm up with both of us at WOT.....and while at top RPM of 5600, he could still not pull away from me. We both had Bravo drives...I had XR's and he had another type of X...we both were running 1:5 gear ratios. I always had my fuel tanks topped off....while he was always looking for one of the gas docks to refuel his tanks.
That's 615hp vs 750+hp....we both turned the same RPM up on top @5600rpm. He would ask me to open my engine hatch and he would just stare at my engines for several minutes....probably trying to hopefully catch me red handed with finding a NOS hose and bottle somewhere. But I told him that it was probably the way my drives were set up on my boat.....extension boxes, -2" IMCO shortys with a nose cone integrated into the IMCO shorty...compared to my buddy's boat not having any of these things. It seemed to be as if it was worth another 300+hp on my boat compared to my friend's same boat....difficult to believe...I know, but we ran raced each other several times over on different days...we do our boating out of the same area.
All else remaining the same and CID for CID, etc, I would still find it very difficult to believe that an NA engine would outrun/perform a supercharged engine within the same RPM power band in the same hull, etc. And if it did, I would have to think it would be very rare...few and far between.
The other funny thing is that I eventually sold him my XR drives.....he said they slowed his boat down by about 2-mph.
03-06-2016, 10:03 PM
#75
Registered
So many people start with building their motors here where they should really start is with their drives and drive heights. Very easy speed and ultimately performance and handling gains that will be necessary once they do build a motor of their dreams.
Just my observation
I remember back in the 80s when I wanted to build my small block in my 18 footer and a guy with a Rep said I would kill the Alpha and I would need to make 50 hp to over come the drag of a transmission and the TRS upgrade.
Than I opened up a powerboat magazine and they had a side by side test of a small block sterndrive against the newly released Arnesons .
Good for 10 mph on the right hull.
Just my observation
I remember back in the 80s when I wanted to build my small block in my 18 footer and a guy with a Rep said I would kill the Alpha and I would need to make 50 hp to over come the drag of a transmission and the TRS upgrade.
Than I opened up a powerboat magazine and they had a side by side test of a small block sterndrive against the newly released Arnesons .
Good for 10 mph on the right hull.
03-06-2016, 10:18 PM
#76
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What is the down fall of them and why not the following so much these days for the obvious power gains that are there?
03-06-2016, 10:19 PM
#77
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i know a guy who tore up his alpha so he installed a bravo drive,he was not pleased with his 2 to 3 mph loss of speed.
03-06-2016, 10:23 PM
#78
Registered
We had a guy running around by me who had a 370 Merc in front of a TRS in a 18 Donzi back n 1980. Thing was set so deep because of the transom height limitations that when he floored it the boat heeled over 15 degrees and stayed there pretty much.
Wasn't real fast either. That was my 1st clue as a kid that horsepower ain't everything.
The guy that advised me about not putting power to my old MR had a Supercharged 460 in front of a number 2 back n 1982 ?
Dry headers in a 21 Donzi GT . Saw some flames out of them one night as I was racing him.knew I was way out of my league
Wasn't real fast either. That was my 1st clue as a kid that horsepower ain't everything.
The guy that advised me about not putting power to my old MR had a Supercharged 460 in front of a number 2 back n 1982 ?
Dry headers in a 21 Donzi GT . Saw some flames out of them one night as I was racing him.knew I was way out of my league
Last edited by tommymonza; 03-06-2016 at 10:30 PM.
03-06-2016, 10:25 PM
#79
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Bummer for him !
Last edited by SB; 03-06-2016 at 10:27 PM.
03-06-2016, 10:26 PM
#80
Registered
the xtra power is because1 the whipple is so much more efficient and2 because it takes less power to turn it,less parasitic loss.the down side is the price,they are not cheep.a lot of boaters have them,the ones that don,t have one want one!
