Like Tree2Likes

Turbo vs blower

Reply
Old 11-28-2007, 04:41 PM
  #61
Platinum Member
Platinum Member
 
BigSilverCat's Avatar
 
Join Date: Jan 2003
Location: Joplin, Mo
My Boats: 2016 50' Skater Catamaran , 2003 41' Apache Cat, 2003 36' Cigarette Gladiator
Posts: 2,466
Default

I dont get a quote?
BigSilverCat is offline  
Reply With Quote
Old 11-28-2007, 06:56 PM
  #62
PF Marine
Platinum Member
 
Coolerman's Avatar
 
Join Date: Mar 2003
Location: Dallas, TX
Posts: 1,767
Default

Quote:
Originally Posted by Bigyellowcat View Post
I dont get a quote?
Lmao... how are the Eickert headers working for you now?
Coolerman is offline  
Reply With Quote
Old 11-28-2007, 07:23 PM
  #63
Registered
 
WeaponX's Avatar
 
Join Date: Feb 2005
Location: LOTO
My Boats: 2400 HP nightmare.
Posts: 1,437
Default

Quote:
Originally Posted by Bigyellowcat View Post
I dont get a quote?
$1.6 Million How is that for a Quote??
WeaponX is offline  
Reply With Quote
Old 11-28-2007, 08:38 PM
  #64
Registered
 
Whipple Charged's Avatar
 
Join Date: Oct 2000
Location: Fresno, CA, 93722, USA
My Boats: Engine, speed, powerboats, Outerlimits SV43 with Whipple 1375SCI's
Posts: 1,436
Default

Quote:
Originally Posted by Joe92GT View Post
Don't forget the HP it takes to spin the blower! Try and rotate a roots and screw blower by hand, feel the resistance? On a 1000hp engine, the supercharger will probably take around 250-300hp. Atleast in the mustang world that was the rule of thumb. So, your 1000hp engine is making 1250 or 1300 or more.

With a turbo, it takes away very little hp, so a 1000hp engine makes only a little over 1000hp. These numbers aren't right on, but the difference is significant and why turbos are gentler on an engine.
You must be refering to a B&M 420 or a roots from 1960. At 1000hp, a good roots should take approx. 150hp and a good screw would take 75hp.

Seperately, turbo motors typically require mid to high compression in the engines, to help increase low/mid range torque. This is also true for camshaft selection, unless you have varible cam timing, most require smaller cams that help increase cylinder pressure at lower speeds. A positive displacement, with high efficiency (screw) can run far lower static compression ratio's and much larger camshafts. Lower static compression allows the engine to have cooler temps/lower cylinder pressures while in 90% of operation. This means longer engine life.

To note, VW is set to release a new vehicle that has "compound boost" which has both a positive displacement and turbo. The turbo feeds the SC. By force feeding the PD, efficiency levels far exceed 100%, but when the turbo can't keep up, the increased vacuum and airflow from the SC helps fulfill that void.

Thanks,
Dustin
Whipple Charged is offline  
Reply With Quote
Old 11-28-2007, 10:28 PM
  #65
Platinum Member
Platinum Member
 
BigSilverCat's Avatar
 
Join Date: Jan 2003
Location: Joplin, Mo
My Boats: 2016 50' Skater Catamaran , 2003 41' Apache Cat, 2003 36' Cigarette Gladiator
Posts: 2,466
Default

Quote:
Originally Posted by saxman View Post
Lmao... how are the Eickert headers working for you now?
they work great for weight to hold down the cover for my jetski, when layed on there side they also work good for holding my mold a few inches off the ground. and I got one of the bums that walks by my shop picking up aluminum cans to sweep my entire shop for one of them.

so they are working out pretty good. although, I think for the $1800 I probaly could have hired some one to sweep my shop floor.
BigSilverCat is offline  
Reply With Quote
Old 11-29-2007, 09:05 AM
  #66
Registered
 
Join Date: Jul 2001
Location: Michigan
My Boats: 43 Checkmate Punisher
Posts: 316
Default

Quote:
Originally Posted by Whipple Charged View Post
You must be refering to a B&M 420 or a roots from 1960. At 1000hp, a good roots should take approx. 150hp and a good screw would take 75hp.

Seperately, turbo motors typically require mid to high compression in the engines, to help increase low/mid range torque. This is also true for camshaft selection, unless you have varible cam timing, most require smaller cams that help increase cylinder pressure at lower speeds. A positive displacement, with high efficiency (screw) can run far lower static compression ratio's and much larger camshafts. Lower static compression allows the engine to have cooler temps/lower cylinder pressures while in 90% of operation. This means longer engine life.

To note, VW is set to release a new vehicle that has "compound boost" which has both a positive displacement and turbo. The turbo feeds the SC. By force feeding the PD, efficiency levels far exceed 100%, but when the turbo can't keep up, the increased vacuum and airflow from the SC helps fulfill that void.

Thanks,
Dustin
While this might be true in some applications, it isn't always the case. My engine is 6.5:1 static compression. The engine makes 2lbs of boost at only 1500 rpms. At 2750 it is already at 1390ft lbs of torque. The cam is not real small. It has 282 on the intake at .50. We limit boost with the ecu to 23lbs. I do run 100 octane unleaded fuel.
check300 is offline  
Reply With Quote
Old 11-29-2007, 09:34 AM
  #67
Registered
 
cougarman's Avatar
 
Join Date: Jan 2002
Location: Michigan
My Boats: 1986 Cougar US-1 46'
Posts: 2,765
Default

Quote:
Originally Posted by Bigyellowcat View Post
I dont get a quote?
Tyson,

I think you have to answer the question to get quoted.

So with your education in the turbo world and everything you have learned good and bad.............why do you feel a Turbo engine is safer or will last longer than a blower engine of equal power in excess of 1000 H.P. ?

Thanks
Jon
cougarman is offline  
Reply With Quote
Old 11-29-2007, 10:44 AM
  #68
Registered
Trade Score: (1)
 
Join Date: Aug 2007
My Boats: 33' Apache (EL BOSS)
Posts: 354
Default

Typicaly we built turbo engines with 10 lbs of boost and around 6 to 7.5 compression. One I remember was a 460 69 tbird single turbo. Pulled 800 lbs of torq if I remember correctly perty much from 2400 rpm to 5200. Turned 11.1 in the quarter mile weighed 5300 lbs.

Big thing with making them last was keeping the RPM low
hard core rotating mass parts as boost increases.
Have one friend that runs a 2000 cc lotus at 40 lbs of boost has busrted everthing in the car but the engine. He went as far as water cooled brakes and machining a billet transmission case for the car.
With the variable geometry stuff I did with the electronic controler boost was available at idle. First over the road truck we put one on when it took off all the drive wheels jumped off the ground at once. We then strapped it to the chassis dyno to dial in the power curve.
turbo2256b is offline  
Reply With Quote
Old 11-29-2007, 12:33 PM
  #69
Registered
 
Join Date: Oct 2007
Posts: 57
Default

Been meaning to jump into this thread for a while, I've spent quite a bit of time with turbos!

The VW system quoted by Dustin above is the VW Twin Charger but you appear to have the operation the wrong way round: The SC feeds the turbo, not the other way around.

The supercharger is very highly gearing and is clutched. It is only there to fill in the gap BEFORE the turbo spools up to ensure good drivability. Since the turbo size no longer has to be compromised to give good response, the match can be a lot larger and so the performance ratio (remember this is a 170bhp 1.4l engine) can be a lot higher.

The SC is only there for response at the low end and has a very large drive ratio as it is clutched. It HAS to declutch before 3000rpm or it's exceed it's allowable max speed. This engine has already been released in the European market.

The SC does not take over when the turbo runs out of breath as you seem to suggest. This would not make sense as quite apart from the parasitic losses associated with an SC (as has already been discussed) as even a screw charger efficiency (isentropic effy) is nearly ten points lower than a typical centrifugal compressor eg the front stage of a turbo. So at max power where the losses are highest, the turbo takes over as it can provide the boost for the lowest cost.

Hope that helps!

Link to schematic: http://bioage.typepad.com/.shared/im...si_airflow.png

Last edited by Ruaraidh; 11-29-2007 at 12:34 PM. Reason: Added link
Ruaraidh is offline  
Reply With Quote
Old 11-29-2007, 01:14 PM
  #70
Registered
 
Join Date: Jun 2004
Location: Freehold, NJ
My Boats: 32 SeaCraft
Posts: 1,381
Default Turbo information

Don't yell at me because I don't post but this thread is up my alley. I was AMT Diesel, we developed all kinds of things for racing diesels and our designs made it into Cummins & Navistar truck engines - turbo and supercharged(roots)

We also ran the racing engines for Super Hero/Buzzi and my own little diesel boats here in the US years ago. We developed the small hi-po diesels that were to be marketed as small Seateks/Super Hero based on Cummins B series engines (also did C's and L-10's to compete with the Seatek)
I pride myself on the shear number of engines we have blown up on the dyno - in the name of developement & testing you have to break them.

Please ask Craig or Bud from Cig/Hawk who I am, no bull.

There are so many things being said here, if you have a question ask me and I'll answer it as best I can based on our cubic dollars of experience.

Joe Gere
HabanaJoe is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
berns29scarab
General Boating Discussion
20
03-27-2008 11:59 AM
CA_Southpaw
General Q & A
3
08-02-2005 03:53 PM
mr_velocity
General Boating Discussion
11
03-03-2004 01:54 PM
wwwTOPDJcom
General Boating Discussion
18
12-11-2002 07:36 PM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 03:12 AM.


Copyright 2011 OffShoreOnly. All rights reserved.