Turbos and centrifugals
 

Curious. I see lots of guys loving turbos and centrifugals these days. I have never driven either of them in rough water.

How do they perform when say you are running hard in big water and on/off the throttles ?

I would think Mild in comparison to big roots Thunder!!! :angry-smiley-044:

Gentry Loved turbos!!! He seemed to do ok! :drink:

In and out of the water, I'd say Positive Displacement Superchargers.

I just bought a set of Gentry Twin Turbos for my next project. Never ran them before, but always wanted to ever since I saw my first Gale Banks setup at the lake years ago. (this endorsement may change later! haha!)

I like Superchargers, but they eat horsepower to make horsepower. More boost, more horsepower, kind of a "Catch 22". Blowers also stick up, particularly with innercoolers, which make hatch mods a given. They're sexy, but kind of big and bulky.

Turbos (apart from a minor exhaust restriction) is free boost. I like the turbos in the marine environment (turbo application to turbo application---not as a comparison to other types) because the throttle use is less (no stop, start, stop, etc.) and a marine engines are always in load, which keeps a positive "spin" on the turbo. Even Merc is moving that way on some of their engines, granted probable because of packaging, but still, the right turbo set up and you can make lots of horses, and still have your lady a place to sun!!!

Centrifugals, I actually bought a set of ProChargers, but changed direction when I found the Gentry's. They are a mixture of both, good packaging, but burn some horses to make horses. What changed my mind about the centrifugals was the noise. I know you can get the helicut gears to help the noise, but most of the folks I talked with said they rattled and whined at idle. I YouTubed some centrifugals and the whine was high-pitched and annoying (to me anyway)

I still have the ProChargers if your interested, will make you a good deal! :)

I have both, well sorta, run procharger on the checkmate, works very well, and even in rough water working the throttle is fine, we drag race a turbo LS car, which also works great but in the rough water in and out of the throttle the blower will work better I think as you get your boost right back and the turbo will lag a bit on most setups..

Nothing is free, or even close to it. If you have ever put on an exhaust back pressure gauge on you would realize this. Back pressure will ALWAYS exceed boost pressure, otherwise the turbine won't drive the compressor. The back pressure reduces efficiency and robs you of power the same way the blower looses through parasitic loss, although at larger power/boost levels the turbo does have an efficiency advantage.

Word. ^^^^^ No free lunch in energy.

A/R ratios make this not necessarily true, wrto back pressure vs manifold pressure. Makes tuning on EGR systems for diesels sometimes interesting.
Turbos are the most efficient because they are largely driven by the heat energy from the expanding exhaust gases that are normally just wasted. Though they do increase pumping losses. No free lunch, but turbos are closest!

The turbo vs procharger is the best head to head , the roots takes you into weight ,height how much zest the snout of the crankshaft has and so on . Good wastgates in a boat twin turbo set up wont have your passengers getting off after a ride saying "yea its fast ,but the lazy throttle response was kind of dissapointing"
But you have spent a ton of money on alloy water cooled exhaust components and intercoolers ,plumbing ect
Even the jet skii crowd tends to lean towards mini procharger and eatons to get some pretty stout hp out of little 1500cc motors and such ,with no driveline comprimise issues . Cept honda of course , with their auqatrax turbo
But when you have a minivan motor in a outboard selling for 20k+ you can go outside the box here and thers

"Free" may have been alittle broad, but even Ford admits the blower on the KR500 motor in the Mustang uses 150hp at full boost, that's more than an exhaust restriction.
Each have their pros and cons. To me, it seems turbos are more "tweaky" , but I like the sound! :thankyouthankyou: we will see

On my old setup in my 30' Checkmate, we had 25 lbs of boost and 25 lbs of exhaust back pressure. So back pressure doesn't always exceed boost pressure.

A good race twin turbo set up with headers and you will never look back!! Had one in a raysoncraft 21 v-drive was pretty bad ass.

The simplicity of the roots is hard to ignore but say you get the the point where you are transfering 150 hp from the face of the crank to the top of the engine into something has some very measurable inertia , you will probably have to start losing some forward passenger space too . And your long haired blond friends in the boat may be reduced to only sitting in the front seat(s) unless they tuck thier hair into tight fitting hats...or you have a big boat where the engine sits deep

good examples of how BSFC numbers can change, based on the type of forced induction, and should not be considered a fuel mixture tuning number.

Exactly. We ran at a 10.9 AFR under boost as that was what the engine wanted.

I like the "WOW" effect of turbo. My setup is old as $h!t, but when people hear that I have twin turbos, they are impressed. My original set up is a 1980 Mercruiser 475 HP twin turbo/ SSM II. Is has RayJay turbo, a PFM intercooler and wastegates. The exhaust risers say Gale Banks on them. I run about 10 lbs of boost. I know that I can easily overpower the TRS drives with the set up. TurboJack gave me some good tips on my set up. I cruise at 3800 at 2 " of vacuum at 40 mph. I can increase the throttles one click and Im making 4 psi of boost and running at 60. Its fun to her the turbo whine. I haven't had mine out in rough stuff (haven't had it running long enough, plagued by engine problems and drive problems) but the turbos are so small that I boost is instant after 3900 rpm.

[ATTACH=CONFIG]542715[/ATTACH][ATTACH=CONFIG]542716[/ATTACH]

A bit OT, but if you like turbo whine go to 3.30 in the vid.

3 x 57 liter W18 diesels, 5000 hp

https://www.youtube.com/watch?v=LXqCzD38zX0

I run an M3SC Procharged with a COG drive on my 540. Made my own main bracket which sets it off to the side of my exh manifold, down low. It's got a shift wine to it at RPM, enough to kno it's there but not annoying. Most get a smile out of it. I'm pullied for about 8 psi at 6300rpm. If I'm anything over 3000 rpm it'll make boost instantly if I open the throttle because the blower is spinning. If I'm light on it just cruising I'll even show engine vacuum. In bigger water I can close the blades, the BOV will dump the excess boost, hammer open and instant boost again. I love it. Very well mannered at the dock, for a cam with 250@50... Being no boost. Easier on drives while getting in plane. Plenty of torque with a 9.2-1 540 and easy on the motor because I only have the boost when I'm in the throttle. It runs way cool and has been very reliable.

Compound turbos in my 6.4L Power Stroke diesel. 700 HP 1300 FT LBs. Live turbos to. If you want no lag, then go smaller chargers. Then you lack the air flow in the top.

Roots take more power to turn, make more heat, boost off idle, look and sound neat.

Different strokes for different folks.

^^^ good info.

One thing i have noticed during some testing. I had always been told roots blowers make tons of heat. I think that can be misleading somewhat.

On icdedppls non intercooled 10-71s on his 540s, making 7ish lbs of boost, intake temps are around 130-140, as long as you hold it wot. Intercooled setup like that around 115*. Now, thats on a blower that isnt spinning to the moon. Ive heard of procharged aetups running similar temps intercooled. Not sure on turbos?

Yeah there's a lot of variables for sure. I can look and see what my diesel head for intake temps but that's so far from the boating world it's not worth comparing. I to have herd the roots take more power and run hotter. Probably because they make boost a lot sooner and are big mother humpers! My PC has a 4.10-1 built in step up radio so the guys running a serp belt have good luck not slipping belts due to the larger pulley's. Mine runs pretty cool with the remote mounted IC running child lake water through it. Size does play in to heat. A smaller red lined blower will run hotter than a bigger one working efficiently. My M3 is only spinning about 42,000 rpm @ 6300 and red line is 50,000 ish conservatively per ATI. I also think that since I'm only under boost while in the throttle I think that helps keep heat down compared other positive displacement units. Some of the mustang street guys I know like to over drive the centrifugals to get the boost in sooner then use a waste gate to bleed off the top end but that's more heat and power to do.

My turbos run hot. 1200 + EGTs . air to air IC.. Drive pressure with my compounds at 40+ psi is 75+. That's a big exhaust restriction. A big single would run cooler with less back pressure, but I would sacrifice either low end spool up or top end flow that way.

From what I understand, a roots style blower makes more power on the bottom end (low RPMS) and the centrifugals make more at higher RPMs.
Most old school guys like the roots style, probaly since they were made popular by drag cars, muscle cars and the type.

To me, a centrifugal makes more sense in boat application. You don't need power below 3000 rpms.

Of course the roots style looks cooler...;)
They do require tall hatches or cutouts (there goes using the sunpad).

I have centrifugals. I don't pull any boost at all until 60 mph so its very fuel efficient at low RPMs (3500 and below). There is a whine with the hatch open, but not anoying at all.

Good comparison here (lot of negatives for roots and screw ;) ):

http://www.superchargersonline.com/i...page=page&id=7

Here's another comparison (but may be biased):

http://www.vortechsuperchargers.com/page.php?id=749

I love this:
"So, when choosing a supercharger system: Do you want power, or do you want a decoration?"

I ran a large intercooler and had air intake temps under 90 degrees at 25 lbs of boost. At full throttle my egts were 1575. I did not run water cooled turbos but did have water cooled heat shields over the exhaust housings.

That is pretty awesome, for intake temps. I do like how much more flexibility with intercoolers you have, with turbo's and prochargers.

On your setup, what size intercooler core was it, and how big of water lines did you have feeding it? I've seen some procharger setups using the stock intercooler with little -8 line feeding the core, didnt seem like enough to me?

I think that article has some false statements. Like a whipple/screw wont keep building power in the upper rpm range?? Thats absurd.

Challenging to achieve high boost levels? Guess they havent tried a PSI blower, 8.3L whipple, quad rotors, etc.

As for roots, one of their negatives was "sometimes violent throttle response". Well, I can see that. Not sure thats a negative though, at least the top fuel guys don't think so. Roots are pretty old technology, but they still have their place today in offshore engines. Plenty of big name builders out there making 1200,1300HP with roots blowers and pump gas. With whipples/psi, even more. Engines that have very broad power curves. I've been on mike tkach's 38 fountain with twin 1200hp 8.3L whipple engines coupled to dry sump 6's. That thing will about put your nutsack in your back pocket when he whacks it at 3500RPM. Boat is a rocket from 60 to 120mph. It's no light boat either, weighing in around 11k lbs or so.

Problem my buddy had with his prochargers, was this. He had a 42 Fountain. Boat would run 115mph+ without even dialing boat in yet. That part was great. However, he had a setup that at top speed, the boat was geared/propped for twin 1200HP engines. Problem was, that at low rpm, like say planing, he was trying to turn 115+mph props/gears, with engines that were gutless "on motor". Like, nearly throttles pinned to the dash, trying to get boat to lay over. Being a centrifugal, he couldnt make any boost getting on plane.

I've seen some big power whipple torque monsters, lay 40ft boats over with 1/4 throttle like nothing. The power is there, if you choose to utilize it, by pushing the throttles forward, I don't see alot of prochargers in MTI's, Skaters, Nortech's, mystic's, etc. There must be a reason other than looks, and it surely isnt cost?

My original question was the whole on/off the throttle thing with turbos and centrifugals, and how they do in that aspect. I know they can make big dyno numbers and top speed numbers. I've been out in lots of rough water, where by the time i get to the harbor my arm is completely numb and about to fall off from throttling thru 20-30 miles of big water on lake michigan. Love the roots in that scenerio.

How would the prochargers work in say racing, in this video?

https://www.youtube.com/watch?v=4ccn53WzOCE

^^^^^^^^^

There seem to be a few offshore race boats running merc turbo's.

My core was 8"thick and 22" long, so pretty big. I used dash 20 lines for all water.

Bad idea, never mind.

What kind of power did this make? How many cid?

It was 572ci and it made 1830hp. That's how I ran it in the boat.