Only problem was the low end getting on plane with all the weight in the back. But once on top would run down most boats.

There is another 41 Apache with like 1100hp I passed on a poker run and he was on the phone I believe with the engine builder in the parking lot when we got back from the run. My buddy herd him tell the guy it was loud don't think it made since to him that a supercharged boat lost to a NA boat. LOL

Which motor will live longer the blown motor or the NA motor?

engines with equil hp the supercharged engine should last longer,espically the valve train.

can you tell i am a supercharger guy,lol.

Thought this was interesting to post.





900 SC, [email protected], 252, lift is .672
Exhaust@ .050. 257, lift is .672


My 598 NA Injected engines needed cams like this to make good power.
.050 I275
.050 E283
.750 lift to make 900hp at 6000. 960hp at 6700. Around 840ftlb tq
The weight of the 2.4 intake valve was tearing up the cam lobe. after about 5 years.

I run the same cams in my 540s 690 hp an 680 tq very ez on valve train na motors

Valve train is working against way more cyl pressure especially on the ex side.

It was a little joke.
You didn't have to explain that.

Did you???

only because i did not know you were joking.

yes but with the right parts it is not a big issue imo.

What does it cost for supercharger rebuild and how often? And how often replace intercooler? Think you will still win with supercharger. But what is the cost difference to do a 900hp motor charged and not? Cost for maintaining valve train over time vs supercharger and maintaining other parts plus investment for supercharging. As far as HP and speed HP is HP unless you cant get it to go from the start. Diesel makes a ton of torque but that wont seal the deal for speed!
HP wins!
Anyone that says different on the HP to speed back it up or don't post it!

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.

Did both sets of motors run on the same dyno? 615 vs 750?

The other apache i ran had the same drives very close x-demension and it was a sisiter hull to mine my hull is 21 it is 20.

Setup can equal speed, would also be curious what his motors made as installed vs on dyno, seen and heard of alot of guys making good numbers on dyno then builder turns timing down, jets up etc to be "safe" in boat (avoid warranty problems)

Back when my 272 only had 675-700 procharged hp I raced a 272 open bow with a big NA motor that supposedly 750 hp, I had 4-5 mph on him. Hard to compare different boats, could be as simple as guy bolted on box stock prop and faster guy tried 5 different props labbed several times. I raced a 33 avs last fall that had 575 hp NA 540s (from what I been told) and crept away from him with my 33avs with stock 500 efis that have rev limiter turned up, I also bought a set of labbed 30's that were spot on, he said he was only turnoing 5200 or so, I would bet he had props that were slightly off, I was also running on fumes, fwiw, Smitty

Going procharged again? I bet you'll have that avs flying.

No---2 different dynos, but my friend actually told me his engines made about 810hp on the dyno at a higher RPM, but said that the RPM the boat propped out at (5600rpm) would probably be more like 750hp or so in the boat. I honestly do not have all the figures. However, I still find it pretty difficult to believe that a NA engine will out perform a Supercharged engine---CID for CID and same RPM band in the same hull. And if it did/does, then it would be something that only happens on a rare occasion. Interesting conversation for sure.

I have heard that Dave Wesseldyk's dyno has a reputation for being on the conservative, unforgiving side, but he always says, "It's not conservative---it's correct, and I always keep a crying towel hanging next to it!" and he's willing to calibrate his dyno for a customer if they want.

For longevity it's always an issue. Roots/centrifugal blower engines are making more power at the piston to have equal power at the crank compared to an equal powered NA engine.. The parts are seeing more abuse...they won't last as long. Simple physics. Most of these engines get rebuilt long before they really need to so it's pretty much a moot point.

thats a good story,,I guess we can stand to reason,his engines didn't make anywhere near 750hp.its even funnier about the drive thing.

scott,the supercharger,no matter the type or brand forces the air-fuel charge in the cylinder .as you said simple physics,the more air-fuel you put in the cylinder the more power it will make.for a n/a engine to achieve a ve similar to the boosted engine it needs much more cam.it also needs a higher compression ratio but thats for another day.what i am saying is the supercharged engine requires way less lift&duration than the n/a engine so even though their is more pressure against the exhaust valve it is still easier on the rest of the valve train than the n/a engine.example,try running a hyd roller on an engine like apache 14 has and see how long that will last,my bet is not long.the 262-270 at .050 with .647 lift hyd roller in my boosted 1200+hp engines won,t make power in his engines,simple physics!i agree with your statement that the boosted engine[ if it has a belt driven supercharger] makes more power at the piston,that is why i made my comment about using the right parts.does that hold true if the boost comes from a turbo charger?

Two comments that I saw that got my attention in this discussion; n/a motor with "equal power" as a blower motor, and "use the right parts". All I was pointing out was there needs to be a alittle more thinking about these comparisons than face value, ie: the blower motor has to make more power (at the piston, where all the work is done) to have the same measured power as an NA engine, so that's not really a fair comparison. It's apples and oranges. Second, qualifying the comparison by saying "if the right parts are used" as if they wouldn't be for one engine, and would for the other in the comparison. I would expect that the "right" parts would be used in either engine, according to the needs of the build.
Turbo engines have a unique circumstance where they run under back pressure during overlap and the piston isn't trying to come off the end of the rod when it changes direction like on other engines. Turbo engines are a lot easier on bottom ends but have their own need as far as reliability and longevity. Cyl pressure is cyl pressure.

Whats a typical roots blower lets say 10-71 eat for horsepower at 1:1 ?
50hp?

good discussion scott.i guess be it 1200 hp n/a or supercharged it will be hard on parts,if not everybody would have them.

i can,t answer that but i read that the supercharger on a top fuel engine uses 1100 hp at 8000 rpm.

dan,i can tell you that my spare engine made 1015 hp with the 16.71 and 1200+with the 8.3 whipple due to the difference in parasitic loss in the superchargers.the 16.71 eats power and generates heat,the whipple does neither.

Probably closer to 150

takes power to make power,lol.

All this motor stuff has ruined car commercials for me.... just saw one on tv enthusiastically claiming 320 hp,, voice in my head went 320hp? your bragging about 320 hp.. lol

In physics, the law of conservation of energy states that the total energy of an isolated system remains constant—it is said to be conserved over time. Energy can neither be created nor destroyed; rather, it transforms from one form to another.

but that 320 hp engine will no doubt see 300 thousand miles.

that,s some deep chit right their.

Huge advantage there. True horsepower from Big Dave and 2, not dragging half of your propulsion , huge drag no matter how much power you have

A 557ci, with an 871, should make 750HP, running on 7 cylinders, unless it was a total chitbomb of a build.

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.

That is a huge difference. I remember when everyone was jumping on the Whipple train years ago.why the power gains?

What is the down fall of them and why not the following so much these days for the obvious power gains that are there?

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.

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

And an Alpha SS (2.5" shorter than reg Alpha) that is usally fine behind mid 400hp small blocks, would have gained 5-7mph (on average) over the reg alpha. Small light boats sometimes gain more ! When these go up for sale, they are typically $2500 or so.

Bummer for him !

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!