26ZX Donzi

Real world -limited resources (poor by OSO standards)-stock not exotic! I purchased a Vortech based system from Livorsi Marine (ask for Ron Harris). It came with a modified ECU, Vortech charger, intercooler. I now have over 200 hours on the motor since adding the system. Real world: blew the outdrive once - blew the head gasket once. Would I do it again? YOU BET! Went from 64gps in a 26 Donzi to 77-79gps. Wanna play you got to pay. This still seems to be one of the most reliable, cost effective systems out there. HOWEVER - To each his own!

tomcat

I love this question... and I hate this question too. So many variables and potential contradictions. But here we go.

The best blower system needs to:

1) Give the greatest HP/speed gains
2) Not blow up your engine
3) Give your drive a chance to live
4) Be good value for the money
5) Be easy to install on nearly stock engines
6) Look good!

Sticking to nearly stock engines makes things more affordable and easier to install, but it eliminates purpose built, big $$$ blower engines with PSI or Quad rotor screw compressors. The contest is between Roots, Whipple and Centrifugal, using the criteria listed above.

IMHO, only the centrifugal blowers can make the big HP numbers on nearly stock engines. They have high compressor efficiency and the way the blower is mounted on the engine leaves room for a huge intercooler. This is very important because detonation is the real limit to how much HP you can make, and the coolest possible intake temperatures are needed.

Dean Nickerson gets 950 HP @ 6000 RPM from a Vortech V-4 blower and a single carb on a 498 CID engine with ported GM cast iron heads and a small solid roller cam. Before installing an Rtech supercooler he was making 850 HP. The extra 100 HP with the supercooler is partly due to cooling but also to much lower restriction to air flow. The same Rtech system on a stock HP500 will make 800 HP @ 5600 RPM. This is affordable $/hp. Dean is still using his stock Bravo drive, although I don't see how it can last much longer.

You could make 950 HP with an intercooled 14-71 on the same engine but you would need much better aftermarket heads. The better heads compensate for the lower efficiency of the roots blower and the small roots intercooler. But the heads would cost more money and the Roots system would be more likely to wreck your drive. The single Whipple has great bottom end torque but you can't make this much HP with a single Whipple, and the Quad rotor would cost more money.

As far as looks go I'm biased. I think the supercooler looks much better than the usual plumbing found on centrifugals, but I know many prefer the look of the roots blower.

That's my $.02. You can easily change my conclusion by changing the emphasis you place on each of the above variables; that's what makes the question so difficult to answer. Any time the magazines try to approach this issue, there is a lot of such debate and usually "everybody is a winner".

There's only one thing for sure...you need a blower!

Tom

tomcat

What... nobody wants to start an argument, I mean discussion.

mikes280

would you like to see my dino sheets on a 540 with a single 3.3 whipple try 1067 hp at 5700 and 1128 ft. lbs. one 1180 cfm carb

MIAMIBOYZ

Better overall performance on your motor.

MIAMIBOYZ

Thet dont trust them for sh^&.

tomcat

Hi Mike:

It's always hard to compare blowers because it seems they are always installed on different engines (heads, cam, displacement, headers etc.), which changes the restriction to air flow that the blower is working against. I'm not saying that your 540 (with aftermarket heads?) didn't make 1067 HP, but if you put your 3.3 Whipple on Nickerson's 498 with cast iron heads you would not be able to make that much power. It would take too much boost to do it and the heat/detonation would be the limiting factor, as it always is.

Any positive displacement blower must be sized to the engine HP you're after. That's why there are 14-71 and quad rotor Whipples. Whipple rates the 3.3 at 775 HP on the HP525EFI. At 1067 HP you're getting into quad rotor territory. This doesn't stop you from changing pulleys and spinning your 3.3 faster, but it is a case of diminishing returns. When we dyno tested Nickerson's engine we tried a smaller pulley and made 1013 HP but he didn't leave that pulley on the engine.

One little-known advantage of centrifugal compressors is that they are much more flexible on the HP range. The same V-4 blower that we used to make 1000 HP on Nickerson's engine is used in Vortech's basic 502MPI kit to make 570 HP. This means a guy can get started with the basic kit, and when he is ready to move up he doesn't need to buy a bigger blower.

I guess the only way this question can be decided is to test different systems back to back on the same test engine, same dyno and ultimately in the same boat. That's way too much work/money, except maybe for a magazine. I doubt that it will ever happen, so we will be able to argue (I mean discuss) this question forwever.

bpine

I have the Mercruiser SC600 in my 26' Scarab #5 drive. The Blower is the B&M 420 Mega Blower!

Bryan

Reed Jensen

Merc may "build" the drives... but they have the cases cast by someone else... I've seen the brochure of the company that casts the components.. No one... no company makes everything on a car or a boat... It just isn't economically feasible. Some companies that specialize in unusual components can make the parts much easier than a large company. When people say "Lockheed" built the F-117 Stealth fighter... well... they assembled it... and made the airframes... but lots of first and second tier vendors manufactured the components... Same with Mercruiser.

vtec

Sorry for the offtopic, but...

Reed:

What company cast mercury's outdrives?

vtec