Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > 1- Porsche Technical Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Quote:
Originally Posted by Craig 930 RS View Post
This Evo forum is pretty cool.

I honestly can't tell if this was serious or sarcastic

I do agree it is funny how some threads can go way off topic pretty quick. New type of DV, to unorthodox tuning, to Evo anti surge tuning and dyno pulls. Heh, funny.

Ehhhh, all in the name of performance right?
__________________
Adam Hennessy
Old 01-31-2008, 06:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #61 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Quote:
Originally Posted by beepbeep View Post
Hmm...interesting. But I still don't get how the bleed helps transient bucking at low load conditions? I mean, if BOV only pops open above 24 psi, it should be shut when bucking occurs as I assume you don't reach 24+ lbs when bucking happens? Thus car would react the same when it comes to bucking with or without the pop-off as bleed is only active at WOT, no?

Regards,
Goran
Goran, assuming this compressor configuration has air noise it's pressure output in this region is not steady. It's more like a sine wave. On test, a sensitive pressure readout will show this fluctuation. Aside from the fact this pulsing can cause all of the EFI problems you describe above, the phenomena is irregular, meaning todays ambient conditions are manageable but maybe not tomorrows. One day it's a steady sine wave the next a full surge or something in between.

Last edited by copbait73; 01-31-2008 at 07:08 AM..
Old 01-31-2008, 06:59 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #62 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,560
Quote:
Originally Posted by copbait73 View Post
Goran, assuming this compressor configuration has air noise it's pressure output in this reagion is not steady. It's more like a sine wave. On test, a sensitive pressure readout will show this fluctuation. Aside from the fact this pulsing can cause all of the EFI problems you describe above, the phenomena is irregular, meaning todays ambient conditions are manageable but maybe not tomorrows.
Hmm if this is true then I guess we could blame Mitsu engineers for choosing engine/turbo combo suspectable to mild bucking under certain conditions? Thus this isolated problem could be mended in quite unorthodoxal way (by fitting controllable boost leak, to the tune of -15HP) but I hope we still agree that pop-off is bad thing and that BOV is a BOV is a BOV, and that there is nothing magical or power-producing in them

P.S.
What BOV did Audi use for their mega-power IMSA cars?

Check it out:



__________________
Thank you for your time,
Old 01-31-2008, 07:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #63 (permalink)
Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,291
Garage
Too funny, Goran.

Here's my far fetched theory. I think the turbocharger being used is being used is going in and out of surge threshold. The BOV is just responding to what it sees in the pressure system. BTW, where in the intake system is the control pressure for the BOV being monitored? Above or below the throttle plate? If above the throttle plate....how far from it?
__________________
Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 01-31-2008, 07:22 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #64 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Quote:
Originally Posted by beepbeep View Post
Hmm if this is true then I guess we could blame Mitsu engineeers for choosing enginee/turbo combo suspectable to mild bucking under certain conditions? Thus this isolated problem could be mended in quite unorthodoxal way (by fitting controllable boost leak, to the tune of -15HP) but I hope we still agree that pop-off is bad thing and that BOV is a BOV is a BOV, and that there is nothing magical or power-producing in them

[/IMG]
Goran, I hope my reply doesn't sound like a lecture but once Adam moved from a 100% stock engine this operating condition was no longer a deficiency on the part of the Mitsubishi engineers. For the same reason you can not bring in their credentials to support assumptions of how far modifications have moved from some implied "safety zone".
I can make a blanket state regarding OE turbocharged cars. Their operating system components are closely matched for life vs cost to the specified power output. This means all attempts of power upgrade will compromise this balance and almost without exception in a negative direction. This is the technical and very real justification for voiding warranties when powertrain alterations are made by the owner.

Last edited by copbait73; 01-31-2008 at 10:25 AM..
Old 01-31-2008, 08:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #65 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Goran, sorry, forgot the BOV. Yes, I agree a BOV is just that. Simple part, simple function.
Actually I liked the days when we pressurized carbs, before CIS, EFI and BOVs. With no BOV, the turbo chuffed on shifts (a nice pneumatic sound ) and tweedled down during downshifts just like the MFI Porsche road racers and the Indy cars of the times. I never experienced, nor heard of, the dreaded turbo thrust bearing failure. I'm not sure how modern EFI will handle elimination of the BOV but I intend to try it.
I was fortunate to grow up in Indianapolis and I lived for May and the Indy 500. I followed it's progression from roadster to rear engine, then to TURBO motors. That was my hook, and 36 years in the business I still love turbos.
Old 01-31-2008, 10:48 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #66 (permalink)
 
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Goran/copbait73......knowing what you know about turbochargers and compressor maps what do you think is required(mathematically) to build an anti-surge compressor housing?

I know the theory behind the technology and how/why it works, but is there a true science to it all or rather just a simple series of ports just behind the leading edge of the compressor inducer that vents"recirculates surge back into the intake tract before the inducer? any formulas math involved to determine size/placement of the post inducer ports or is it a shoot from the hip kinda deal?

I've got a few comp housings on the way here to toss in the CNC and cad some stuff up for machining, but if I have a good idea/starting point it'll help me get this moving much quicker. I've got about 5 weeks to tinker with this idea before I have to give this particular car back to the customer ready for racing

-Adam
__________________
Adam Hennessy
Old 01-31-2008, 11:40 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #67 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Adam, I'll collect a few spare parts and send your way. The business has excellent aero engineers and codes now, however IMO porting is still in the realm of art. Also port location is often unique to the wheel design, so you if you are willing to cut and try you are capable.
Besides, it sounds like there is a ready market for these if you succeed.
Old 01-31-2008, 12:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #68 (permalink)
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Quote:
Originally Posted by copbait73 View Post
Adam, I'll collect a few spare parts and send your way. The business has excellent aero engineers and codes now, however IMO porting is still in the realm of art. Also port location is often unique to the wheel design, so you if you are willing to cut and try you are capable.
Besides, it sounds like there is a ready market for these if you succeed.
Spare parts as in dummy housings? You are a fantastic person I love prototyping stuff and figuring these things out and if I need to sacrifice a handful of 16G compressor housings to the gods of compressor surge in order to figure this out, I'm all in. no better way to tackle this stuff than trial and error I guess.

Is there a way I can get a hold of you directly? Phone number or email perhaps? You can send it in a private message or to my email below if you don't want to post it here.

r247motorsports@gmail.com is the email.

Best Regards,
__________________
Adam Hennessy
Old 01-31-2008, 01:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #69 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,560
Quote:
Originally Posted by BoxxerSix View Post
Goran/copbait73......knowing what you know about turbochargers and compressor maps what do you think is required(mathematically) to build an anti-surge compressor housing?

I know the theory behind the technology and how/why it works, but is there a true science to it all or rather just a simple series of ports just behind the leading edge of the compressor inducer that vents"recirculates surge back
into the intake tract before the inducer? any formulas math involved to determine size/placement of the post inducer ports or is it a shoot from the hip kinda deal?

I've got a few comp housings on the way here to toss in the CNC and cad some stuff up for machining, but if I have a good idea/starting point it'll help me get this moving much quicker. I've got about 5 weeks to tinker with this idea before I have to give this particular car back to the customer ready for racing

-Adam
Hmm...I own a Garret GT40 (soon to go in my Audi S4) with anti-surge mumbo jumbo inlet but frankly, I don't quite understand how it works. The anti-surge pockets don't look like something you could machine into compressor housing as intake mouth is much bigger on one with anti-surge.

Antisurge:


Without:


The anti-surge part pushes the surge line to the left felt where mass flow is low but pressure ratio is high.

__________________
Thank you for your time,
Old 01-31-2008, 01:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #70 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Wow, that map has killer efficiency!
Old 01-31-2008, 01:58 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #71 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,560
Quote:
Originally Posted by copbait73 View Post
Goran, sorry, forgot the BOV. Yes, I agree a BOV is just that. Simple part, simple function.
Actually I liked the days when we pressurized carbs, before CIS, EFI and BOVs. With no BOV, the turbo chuffed on shifts (a nice pneumatic sound ) and tweedled down during downshifts just like the MFI Porsche road racers and the Indy cars of the times. I never experienced, nor heard of, the dreaded turbo thrust bearing failure. I'm not sure how modern EFI will handle elimination of the BOV but I intend to try it.
I was fortunate to grow up in Indianapolis and I lived for May and the Indy 500. I followed it's progression from roadster to rear engine, then to TURBO motors. That was my hook, and 36 years in the business I still love turbos.

Hehe...a guy I know happend to have a old 935 in his shed (with correct flat fan and water intercoolers). I checked out the motor and it actually had a sort of BOV. It had pop-offs actuated by throttle. When you lift off throttle, those pop-offs open

Had pictures of it somewhere...
__________________
Thank you for your time,
Old 01-31-2008, 02:00 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #72 (permalink)
 
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,560
Quote:
Originally Posted by copbait73 View Post
Wow, that map has killer efficiency!

Yup. I tried to explain that to "the Garret flange doesn't mach so it's bad" KKK-crew for few years but they won't listen
__________________
Thank you for your time,
Old 01-31-2008, 02:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #73 (permalink)
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Goran,

There's a few different typer/styles of the ported shroud or anti-surge housings out there:

here's a Tial-modified housing



here's another option, probably the route I'm looking into:



And here's a good shot of turbonetics new design on their GTK lineup... BTW these turbochargers are very nice.



here's a picture behind Garretts anti-surge and roughly what it does:




The function of the anti-surge basically reroutes some airflow back in front of the inducer to stave off surge a bit longer, in this essence like you said pushing the surge line farther left away from the choke. From the picture the technology looks quite simple, but i'm sure it's a mess to figure out. I've got to give it a shot though in nothing else.
__________________
Adam Hennessy

Last edited by BoxxerSix; 01-31-2008 at 03:17 PM..
Old 01-31-2008, 02:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #74 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,560
Quote:
Originally Posted by BoxxerSix View Post


here's a picture behind Garretts anti-surge and roughly what it does:


The function of the anti-surge basically reroutes some airflow back in front of the inducer to stave off surge a bit longer, in this essence like you said pushing the surge line farther left away from the choke. From the picture the technology looks quite simple, but i'm sure it's a mess to figure out. I've got to give it a shot though in nothing else.
Hmm...Garrett's antisuge channels actually portrude to compressor blades. Turbonetics mumbojumbed intake looks like nothing else but few holes not actually connecting anything?

Frankly, I'm quite skeptic when it comes to aftermarket modifications of turbochargers. There are heaps of shops claiming to "improve" turbochargers but they cannot prove anything. No maps, no nothing. Turbocharger test rigs cost millions of dollars and these guys only machine a couple of grooves and claim it's "a black art". Clipping wings is probably the worst "improvement". It buggers up the efficiency but pushes the surge line somewhat...
__________________
Thank you for your time,
Old 01-31-2008, 02:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #75 (permalink)
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Quote:
Originally Posted by beepbeep View Post
Hmm...Garrett's antisuge channels actually portrude to compressor blades. Turbonetics mumbojumbed intake looks like nothing else but few holes not actually connecting anything?

Frankly, I'm quite skeptic when it comes to aftermarket modifications of turbochargers. There are heaps of shops claiming to "improve" turbochargers but they cannot prove anything. No maps, no nothing. Turbocharger test rigs cost millions of dollars and these guys only machine a couple of grooves and claim it's "a black art". Clipping wings is probably the worst "improvement". It buggers up the efficiency but pushes the surge line somewhat...

So true when it come to this aftermarket stuff. I don't trust much outside KKK, Turbonetics, and Garrett. Maybe Holsets on diesels. I know the Garrett and turbonetics stuff works very well in properly matched applications.

At the base of each one of Garretts four surge slots in the intake are ports that lead to an undetermined area located in the area of the inducer intake, just behind the actual leading edge of the buckets. I have no idea how big these ports are, but that's where the back flow comes from.

On turbonetics design, each one of those machined "flutes" in the tapered inlet has its own little port at it's base that leads to a similar location on the backside of the inducer. I've worked with the GTK series alot here and if you take off the compressor housing and look down the inlet you will see a matching number of small holes around the inside perimeter of the intake bore. You can't see them with the compressor in the way. Probably just a different design to get around a specific patent or two.

I always wondered what the mapping machines looked like. I have a VSR balancing machine and flow bench here that I've used in the past when I used to rebuild turbos day in and out but they're probably a far cry from what the big companies use to get their results and map plots
__________________
Adam Hennessy
Old 01-31-2008, 02:55 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #76 (permalink)
Registered User
 
BoxxerSix's Avatar
 
Join Date: Jun 2006
Location: Ballston Spa, NY
Posts: 528
Goran, i edited the picture in my previous post that shows how the anti-surge works. I added a few parts that shows how the turbonetics version works. Bright green part is one of those machined ports and the blue line is the airflow path from behind the compressor inducer(light blue). Orange part is the compressor back plate....

Just for reference incase you wondered
__________________
Adam Hennessy
Old 01-31-2008, 03:19 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #77 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Quote:
Originally Posted by beepbeep View Post
Hehe...a guy I know happend to have a old 935 in his shed (with correct flat fan and water intercoolers). I checked out the motor and it actually had a sort of BOV. It had pop-offs actuated by throttle. When you lift off throttle, those pop-offs open

Had pictures of it somewhere...
Yes, that's the valving I had in mind when I suggested the option of a mechanical linkage to the throttle in my #39 posting. This gives a more positive, predictable, progressive control of transitioning the manifold back to non boosted naturally aspirated condition. I try to avoid comparing it's function to that of a modern pressure activated intake recirculation valve (BOV). The turbo could still surge with these because they were often placed between the CAC and throttle, vs common today turbo and CAC.
Old 01-31-2008, 05:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #78 (permalink)
Registered User
 
copbait73's Avatar
 
Join Date: Nov 2003
Location: Chesterfield IN
Posts: 1,314
Garage
Quote:
Originally Posted by BoxxerSix View Post
I always wondered what the mapping machines looked like. I have a VSR balancing machine and flow bench here that I've used in the past when I used to rebuild turbos day in and out but they're probably a far cry from what the big companies use to get their results and map plots
What you see in it's various forms are just pressure bleed off. As you know surge is a condition where the pressure downstream of the entire compressor stage cannot be held and reverses flow. Well this can happen within the flow path of the wheel also. Most often in the inducer area. What you see on Garrett turbos is productionized. It's a very common feature on modern turbos using W/G or VNT.

Turbonetics interpretation is obviously not for high volume. Since Garrett's specialized, cost is no barrier, motorsports turbos do not incorporate this exotic configuration I assume there is no improvement unique to it...but maybe there is(?).

The test stands are gas fired burners with instrumentation. You could find a burner liner from a surplus gas turbine engine and make your own. Your real challenge is the very high volume of compressed air needed. A surplus jet-start unit could be adapted. Once you get running you could feed the turbo compressor back into the burner inlet and shut off the external compressor.....a jet engine.
Old 01-31-2008, 05:52 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #79 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 04:50 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.