Supercharge or Turbocharge
 

After this summer and the sale of my APU Supra I want to build a BBC for my 22' Scarab. I have extensive expertise in turbocharged, fuel injected applications and as a project I would like to go in this direction. However most of you guys I noticed like the blowers. Please weigh in and tell me why.

Less heat under the hatch.... boost remains constant with engine rpm. No turbo lag.... No frying the salt water inside the turbo heat shield....No "Hyper corrosion" from the super heated salt water. I guess in certain aplications... diesel... fresh water cooled... not a problem... I had them on my boat when I first got it.... had to take a cutting torch to all the exhaust studs to get it apart....

More torque at lower RPM's with superchargers... also less lag.

I have run both and have to say I have had alot more trouble with the turbo engines than I did with the blower engines. Turbos were fast I will grant you that BUT also more downtime.

But.... those are all pluses.

Supercharger makes power from 1 RPM and up. More low end coming on plane power to blow a drive.

Plus, where are you RPM wise most of the time in the boat? 3500 or so RPM right? Right where turbos are making Boost. You dont need a TON of power from a stop...

Use turbochargers if you can. Not much info is readily available, although power is awesome and lag can be tuned out with proper sizing and efi. Thats what Ive found. Greg

Actually big inch with turbos would work better!

Why give away 10% crank HP to a blower pully?

TURBO!

Reed, it sounds like you were running lean if you had that much heat to mess up exhaust studs.

blower or turbo doesnt matter as long as they boost but Big inch is a must
:)

Oh I'm not worried about lag. I can get one to react as quick as a supercharger with no problem. I'm concerned mainly about exhaust problems that any of you may have had. reversion, supercooling, and bearing life due to thermal shock. I know for a fact that you shouldn't cool one too quickly. have any of you used a water cooled unit or is it best to stay with oil cooled units for marine use.

Roby

Roby

Super chargers have their own oil supply for the gears.. Turbos have to have engine oil plumbed to them. Then if you shut down while they are hot... you coke up the center sections. Turbochargers are perfect for airplanes. Lots of cooling air and constant engine rpm's. As the air gets thinner the turbo works better than a supercharger. A Turbo is more efficient because it captures the wasted energy going down the exhaust pipe. The big drawback that I experienced was the corrosion, the heat, and the turbo lag. If your boat is going to be cruising at a steady speed all the time on fresh water... such as crossing one of the great lakes.. and you aren't coming on and off the throttles.. they work great... But if you want to be able to blast up the face of a wave... throttle back ... and then slam the sticks down on the backside of the wave... go with the superchargers. MY .02 worth.

..... The problem wasn't so much from heat... as it was from electrolysis... The aluminum manifolds had welded themselves to the studs.

Turbos in a closed engine boat are a real hassel. The exhaust must be stainless or it will crack. I believe the coasties will require it to be water jacketed. They won't accept a system with thermal wrap. That'll put the custom exhaust alone around $7k! A blower can be used with stock manifolds for around $1500. A boat also can not rev like a car, so turbo lag when planing can be a significant issue.

I agree with what others are saying here. Supercharge it. Lot less hassle from what I've witnessed. That little Scarab should fly when your done.....I need to do the same thing to my Hammer.

That is another issue unto it's self... when you have to water jacket the exhaust... you lose the heat from the expanding gasses and the turbo becomes less efficient. I can remember a few years ago Chev racing dept was trying to adapt a big block with sleeves down to the size of a small block... and run multiple turbos with heat wrap.... I think they weren't allowed to run... and they also had such development problems they pulled the plug on the project. Any one else remember the story?

One main thing you have to remember is that a turbo puts a constant blue flame into the engine manifold.

if you lauch alot you have to throttle back to keep from killign yoru engien and drive (if you go fully airborne) and withat turbo when you thorrlte back the loose exhuast pressure and boost. Then when you land and power back up you have have to wait for eth turbos to spool up again.

The technological advances in the turbocharger/EFI industry in the last year have been more than the last five combined. My personal turbo exp. is with big bore Suzuki 1300s. I had one that made 305hp at the rear wheel, bike was scary. That was in 2001. Now, the same guy who I bought my turbo from can build you a 500lb. bike with 575hp at the rear wheel---streetable. It's all in the 'tronics---and most of these are intercooled.
IMHO putting an intercooler in a boat would be a necessary mechanical challenge, seems to me you'd have to completely shroud it with a fan(s) to get the heat out of the boat. If one could do that, using an air cooled(fans) intercooler or getting kinky with a dry ice system, on a big block with strong rods, a lot of horsepower can be made.

Aug. 2003 issue of Chevy High Performance mag has a vette with a twin turbo intercooled 400 sbc making 1300hp on pump gas, daily driver. SICK. :eek:

And if you could build an efficient intercooler system, you wouldn't have to use foot wide slow spool monster wheels that make boocoo heat. And no blue flame down the gullet... :D

How do you figure an intercooler will help with the blue flame effect... all the intercooler does is help keep the detonation under control by cooling the intake charge..... The more you stuff into the cylinder... the more that comes out the exhaust and pushes that much more into the cylinders until the waste gate opens or the turbo is limited by the size of the nozzle, and your statement. "getting kinky with a dry ice system" Part of NOT going with turbos is so that you DO NOT have to get all kinky with tricks. Who wants to stop at the dry ice plant to go boating? Some people want reliable horsepower with out having to resort to voodoo efforts.

If you ever want to sell your boat one day;
1. Big Cubes NA
2. Blower

If you want to keep it till you die of old age;
Turbo

I think you should just put nice stock power under the hatch and bolt a JATO rocket on top that way you can have the best of both worlds, turn key reliability and speed at the touch of a button.:D

Here I heard this baby rocks!

yeap! I agree!

Where is Tom Earhart???He is the King of marine turbo he rocks!!!!last I heard 1400+ hp one bad a$$ ride!!!

Ok first as far as intercooling in a marine environment I would never consider an air-to-air system. This would be dumb because you are sitting on a world of cool water just outside the boat. Water cools 25 times more efficiently than air. Why wouldn't you go with a water-to-air IC setup like the GMC Syclones & Typhoons? One concern I have about blowers is that they have a short life before they need to be refreshed. Now correct me if I'm wrong about that because my SC experience is lacking. Turbo lag can be minimized by using 2 ball bearing S-trim (or H-trim) turbo with the proper A/R ratio. BOVs can also be used to eliminate compressor surge when the throttle is dropped. In the past I have developed a way to isolate the heat from the turbine side and the compressor side without the use of the fire prone thermowrap. (I know I lost my GMC Syclone #811 to a thermowrap fire) I just think that if I can find the correct water jacketed manifolds I think I can get this to work successfully. I really want to keep my engine hatch looking stock too which pretty much means a roots type blower is out. I feel comfortable building a turbocharged engine because of my experience. I have put together a 2835cc Toyota inline 6 that makes well in excess of 850 HP and it gets driven almost daily. I had to go as far as to manufacture my own fuel rail system to fit with the newer T51 turbo. I have no doubt I can make big horsepower this way and have NO downtime if I can get the exhaust plumbing straightened out.

Thanks for all the great replies.
Roby

I have had turbo power for the last 25+ years. With waste gates you do not have to worry about lag. At least I did not have any. From off idle if you hammered the throttle it was instant max. boost. I had dial on dash where I could change from min. 4.5 lbs to max of 17. The setup I had (gale banks) the exhaust manifolds were limiting my max HP. The main problem I had was it was too easy to crank more boost into the engine. Richard Lee makes an awesome setup for turbos. I have 2 friends that have his setup.

I went the pro-charger & Cami header route 3 years ago & have not looked back. Motor is running 10lbs now & holding up better that before (harder to increase the max boost now) with more HP then I had before with turbos @ same boost.

Supercharge it for the water.

Turbo for the street.

Who said a supercharger has a short life span. I run a whipplecharger and it will alst a long time. It is based on the Eaton design which is the same one used by most car mfgs and the car will go 100k+.

Keep and eye out for a used whipple setup on ebay. It will also have an air to water intercooler that is extremely efficient.

BOOST BABY !!!!:D :D

I used to have a twin turboed engine. It ran great! It was an olderstyle turbo system with a blowoff vavle on the carb box. boost would start to build at about 2800rpms. When getting on plane, the engine only had to build a few hundred rpms when the boost would start to come on. Then I had to back out of the throttle to keep from breaking the prop loose.
It had log style manifolds and water jacketed turbos.

I've often wondered if a turbo could be adapted to a Gil style manifild. Seems like it would be a natural fit.

I agree with Troutly.... Rootes type superchargers will go many more hours than the engines themselves. Most of the time turbos will be seizing and coking their center sections a lot faster than a supercharger will be wearing out it's seals and bearings. A supercharger with worn seal strips will still pump and work to a certain degree.... the strips can only wear so much... but once a turbo is seized....or the bearings are gone... it is dead matter in the path of the exhaust... talk about stuffed up performance!

Or it will blow all of you oil into the intake.:eek: :eek:
I had that start to happen once.

Blowers are easier to install and setup.

Something everyone who has posted is overlooking is that turbo boost is FREE. You can make the same power with less boost than a screw because you lose power to the pully.

roby yeah you're right about water to air I wasn't thinking... :o

Coking? If it happens it's the operators fault.

http://zhome.com/ZCMnL/PICS/turboCha...gerBasics.html

http://www.finishrad.com/catalog/greddy-turbo-timer.htm

http://www.grc.nasa.gov/WWW/Oilfree/index.htm

For those who may not know, if you use a water cooled center section with a ball bearing turbo and you change your oil regularly then coking is a non-issue. Also you will no longer need to run that idle period before shut down.

Roby

No need to worry about the intercooler design. There are a couple very good marine designs on the market already. Extensively used in Water Ski Racing applications up to 1400hp. Richard Lee setup is the most popular now. He has water jacketed SS headers that work very well. Alternately, Gentry developed a system with a nice intercooler (the newer ones are much larger and more efficient) as well as aluminum manifolds.

The following west coast engine builders/suppliers have a ton of experience with Marine EFI Turbo setups, mainly due to their ski racing involvement. They would be able to provide advise on whether this is a good application or not and what to look out for. They could all sell you the right equipment to set it up too:
Richard Lee/Lee Performance Products
Gordon Jennings/Pfaff Racing Engines
Bob Teague/Teague Custom Marine
Gary Teague/GT Performance
Boost Power USA

Good luck

Hey Guys.... if the turbo and all it's plumbing gives you a boner... go for it... I really don't care... I'm not going to stuff a supercharger down your throat... I personally wouldn't want a turbo on a boat... I've had them on cars.. they are a neat concept..they work well in a car .. but NO MATTER WHAT YOU DO.... THEY STILL FRY THE SALT WATER IN THE HEAT SHIELD AROUND THE TURBO. So much for the power from a turbo being "free". I've been through all the cracked header/cracked heat shield/salt encrusted/ b/s that I care to...I've had a turbo set-up on a boat before... I'm not really concerned about the power loss through the pulley.... I'm concerned about having to disassemble my intake system every other week to keep it working. I'm concerned about even being able to get it apart without having to torch off studs because of the excessive heat around the turbine section. You want a turbo.... put on four or five for all I care....

I'm sorry you had so many problems Reed, but I must ask how is water getting around your turbos heat shield?

Roby

Roby... the turbos stuff is long gone.... the boat got 10-71's.... The original turbos had stainless hollow heat shields that covered the turbine section of the turbocharger... that section of the turbo glows bright orange under boost.... even when the engines had been idled down for some time... the remaining heat in the turbo would boil the water left in the heat shield... causing lots of salt buildup... inside... . On a Blown set-up... the headers never get that hot... the engine block never gets up to the boiling point.. but on a turbo set-up... the turbine side always gets hot.. this particular set up was an adaptation of automotive turbos to marine... so the heat shields were not integral with the turbos... they were merely water cooled shrouds... If you remove too much heat from the turbo.. you lose it's effectiveness.... because the power captured by the turbo is nothing more than expanding gasses from the combustion process... if you cool them.. they contract... If you look at a airplane installation of a turbo... the exhaust pipes are wrapped with insulation to keep the heat in. That insulation is not to protect the surrounding area from the heat... but to keep the gasses hot and expanding. You can't do that on a boat because of coast guard rules.

I understand all of that but you threw me with the watercooled shrouds. I never heard of such thing.

Roby

No problem Roby... I did most of my boating in salt water.. salt water heated above 150 degrees becomes very corrosive to iron. On the water cooled sections of the turbos there was lots of damage from corrosion... that is the main reason I'd never go back to turbos on a boat. If it were solely a fresh water application... there probably would not have been so many problems.

Supercharged!
Easy to install, no exhaust mods, nothing exotic. Monster torque from idle on up. I did break two transmissions and went to a Huber kryptonite and problem solved.
Learn from my mistake. Everything after the engine has to be rated stronger than the engine or it will break. And it only breaks at the best part of the summer.
Have fun!
Ed