Forged pistons - SaabCentral Forums
*
Home Saab Pictures Saab Classifieds Saab Dealer Listings Saab Forum Saab Forum


Go Back   SaabCentral Forums > Saab C900, 1979-1993 & '94 Convertible (C=classic) > C900 Performance, Mods & Tuning

C900 Performance, Mods & Tuning Covers Tuning & Performance modifications for the Classic 900 (C900)

SaabCentral.com is the premier Saab Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 14th March 2002
Janne Selinummi Janne Selinummi is offline
Saab Lunatic
 
Join Date: Jan 2002                                                
Location: Turku, Finland
Posts: 1,072
Default Forged pistons

A guy at a Finnish performance bulletin board claimed that the forged Mahle pistons
(as used in all Saab Turbo models) are not reliable when running more than 1 bar boost.
He said that at that kind of boost level, the pistons wouldn't last very long.

Is that completely bull$hit? I mean, not all you people driving around those heavily modded c900s have some custom racing pistons, or...????

Can I use my T8 APC pistons to run 1.4 bar of boost?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 15th March 2002
Fan-TC Fan-TC is offline
SaabNut!
 
Join Date: Jan 2002                                                
Location: Australia
Posts: 262
Default

Well i have never experienced any inherrant weaknesses with the Saab Spec pistons (unless you allow detonation).

One excellent Mod i once saw was a 2.0L 9000 turbo motor that had been stripped and rebuilt with stock low K's rods and crank and used very early model low compression pistons (bout 7:1 with 16v head i think). This was then put back into the 9000 (cause of its strong gearbox) and was fitted with a turbo from an early 930 Turbo porsche and 9000 IC (2bar Boost).
I never rode in the car but with the aftermarket engine management it ran beautifully, although slightly laggy.
It ran a high 12 quarter mile on slicks (owner disapointed) before it was destroyed by a big tree.

However these were Second Hand Saab Spec pistons suporting 2bar (400hp+) without breakage.
Reply With Quote Quick reply to this message
  #3  
Old 15th March 2002
Eric van Spelde Eric van Spelde is offline
Saab Crazy
 
Join Date: Feb 2002                                                
Location: The Netherlands
Posts: 520
Default

Yes, this is complete bullsh*t. Apart from unlikely and unfortunate coincidences that mostly involve a complete drainage of engine oil, the only likely way you'll break a stock Mahle piston on a Saab is allowing your engine to knock.
Reply With Quote Quick reply to this message
  #4  
Old 17th March 2002
Alanb Alanb is offline
Saab Crazy
 
Join Date: Aug 2001                                                
Location: West Bath via Sussex, Stirling and Essex
Posts: 622
Default

Didn't Raul destroy his pistons (or was it bent rods?) by running at 30psi?

In my experience these pistons can take a hell of a lot so long as knock is kept at bay.
Alanb
Reply With Quote Quick reply to this message
  #5  
Old 17th March 2002
Eric van Spelde Eric van Spelde is offline
Saab Crazy
 
Join Date: Feb 2002                                                
Location: The Netherlands
Posts: 520
Default

Well, IIRC the reason he got to 30 psi in the first place was him removing the APC system...
Reply With Quote Quick reply to this message
  #6  
Old 17th March 2002
Smackrazor Smackrazor is offline
Saab Lunatic
 
Join Date: Sep 2001                                                
Location: Santa Cruz, Cali
My Saabs: '92 Green 900 Turbo wSPG Kit
Posts: 1,313
Default

And secondly his car was completely unmodded besides that :smile:
Reply With Quote Quick reply to this message
  #7  
Old 30th June 2004
Matthew's Avatar
Matthew Matthew is offline
Saab Mad
 
Join Date: Dec 2001                                                
Location: Gloucestershire, UK
My Saabs: 900 S Aero Turbo, 9-5 Aero
Posts: 14,069
Default

What is the weight difference between a cast and forged pistons? Assume they're for the same application.
Reply With Quote Quick reply to this message
  #8  
Old 30th June 2004
Alex's Avatar
Alex Alex is offline
Saab Lunatic
 
Join Date: Aug 2001                                                
Location: Crossing the England/Wales border
My Saabs: 3dr c900 T16RA, 9-5 Aero Estate
Posts: 4,666
Default

Not sure what the weight differences are but on the Mk1 Impreza the WRX used cast and had a 7000rpm limit the WRX STi used forged and had an 8000rpm max.
Reply With Quote Quick reply to this message
  #9  
Old 30th June 2004
nutcase's Avatar
nutcase nutcase is offline
Super Moderator
 
Join Date: Mar 2003                                                
Location: The Nut Hut
My Saabs: 1978 99T in black; 1983 99GL in Beige
Posts: 11,225
Default

All I know is an equivalent forged item will be heavier than the cast version.
Reply With Quote Quick reply to this message
  #10  
Old 30th June 2004
Alex's Avatar
Alex Alex is offline
Saab Lunatic
 
Join Date: Aug 2001                                                
Location: Crossing the England/Wales border
My Saabs: 3dr c900 T16RA, 9-5 Aero Estate
Posts: 4,666
Default

But due to the superior material properties available when forging something, less material thickness needs to be used so the item can be made lighter.
Reply With Quote Quick reply to this message
  #11  
Old 30th June 2004
4saabstoomany's Avatar
4saabstoomany 4saabstoomany is offline
Saab Lunatic
 
Join Date: Oct 2002                                                
Location: Reading/Gettysburg PA
My Saabs: 86 900T
Posts: 1,249
Default

those after market forged pistons are a pain anyway. Don' you have have to let your car warm up a while to let the pistons expand so they don't jar around in teh cylinder? or something.
Reply With Quote Quick reply to this message
  #12  
Old 30th June 2004
nutcase's Avatar
nutcase nutcase is offline
Super Moderator
 
Join Date: Mar 2003                                                
Location: The Nut Hut
My Saabs: 1978 99T in black; 1983 99GL in Beige
Posts: 11,225
Default

I'm not doing very well today! Just nosed through my A series books and you're right. I got it the wrong way round again!
Reply With Quote Quick reply to this message
  #13  
Old 2nd July 2004
4saabstoomany's Avatar
4saabstoomany 4saabstoomany is offline
Saab Lunatic
 
Join Date: Oct 2002                                                
Location: Reading/Gettysburg PA
My Saabs: 86 900T
Posts: 1,249
Default

we'll let it slide today nutcase

so whats the verdict? are they worth the hassle?
Reply With Quote Quick reply to this message
  #14  
Old 2nd July 2004
ejenner's Avatar
ejenner ejenner is offline
Banned
 
Join Date: Nov 2003                                                
Location: www.saabsforum.com
My Saabs: 900 Carlsson, 99t, 99 T16, 900 t16 vert
Posts: 7,270
Default

I was looking at a site yesterday http://www.thedodgegarage.com/the_reliant.html where a guy had decided to wrench some extra performance out of some really ugly (IMO) American car. He was using the thing for drag racing and it explains how he managed to melt a piston.



He explains that this happened because he fitted a new intercooler which allowed lots of air into the system and effectively reduced the octane in the fuel. These pistons were stock cast pistons and not forged. He was running 21-30 psi with extra injectors which was getting him 12.6 @ 108mph over the 1/4 mile. He replaced with forged pistons and managed to get his time down to 10.5 @ 130 mph. This required lots of mods tho... It was an interesting read.
Reply With Quote Quick reply to this message
  #15  
Old 5th July 2004
rally900's Avatar
rally900 rally900 is offline
SaabNut!
 
Join Date: Oct 2003                                                
Location: usa
Posts: 456
Default Re: Forged pistons

Quote:
Originally Posted by Janne Selinummi
A guy at a Finnish performance bulletin board claimed that the forged Mahle pistons
(as used in all Saab Turbo models) are not reliable when running more than 1 bar boost.
He said that at that kind of boost level, the pistons wouldn't last very long.

Is that completely bull$hit? I mean, not all you people driving around those heavily modded c900s have some custom racing pistons, or...????

Can I use my T8 APC pistons to run 1.4 bar of boost?

I don't want to burst your bubbles here guys but...

...all stock saab pistons, turbo or otherwise, are CAST not forged. However i have never had any problems running up to 18-20 psi and even ran one engine at 22-25psi for 100,000 miles before the bottom end started getting soft (rings, and the bottom end had 250k at that point).

However I have heard many instances of piston melt from running high boost with improperly tuned engines. But yeah, forged pistons are worth it. and you don't have to go aftermarket- there are a number of stock cars that came with forged pistons from the factory. the escort cosworth for one. and yes, the pistons fit, with just a touch of machine work.

james
team saabworks
Reply With Quote Quick reply to this message
  #16  
Old 5th July 2004
ejenner's Avatar
ejenner ejenner is offline
Banned
 
Join Date: Nov 2003                                                
Location: www.saabsforum.com
My Saabs: 900 Carlsson, 99t, 99 T16, 900 t16 vert
Posts: 7,270
Default

Everyone on here believes the pistons from the Turbo cars are forged. How do you know they aren't?

I only think they are because so many people mention it so often..
Reply With Quote Quick reply to this message
  #17  
Old 5th July 2004
Matthew's Avatar
Matthew Matthew is offline
Saab Mad
 
Join Date: Dec 2001                                                
Location: Gloucestershire, UK
My Saabs: 900 S Aero Turbo, 9-5 Aero
Posts: 14,069
Default

The stock pistons are most definitely cast. Every authorititive source on the subject has stated clearly that to be the case.

For the 0.8bar boost that a stock T16 uses, forged pistons simply aren't required.
Reply With Quote Quick reply to this message
  #18  
Old 5th July 2004
nutcase's Avatar
nutcase nutcase is offline
Super Moderator
 
Join Date: Mar 2003                                                
Location: The Nut Hut
My Saabs: 1978 99T in black; 1983 99GL in Beige
Posts: 11,225
Default

I thought the rumour was the 99T pistons were forged? Of which I have no idea about. The manual lists teh dish depth and diaemter, but just has a - for weight (the others are listed).
Reply With Quote Quick reply to this message
  #19  
Old 6th July 2004
rally900's Avatar
rally900 rally900 is offline
SaabNut!
 
Join Date: Oct 2003                                                
Location: usa
Posts: 456
Default

Quote:
Originally Posted by ejenner
Everyone on here believes the pistons from the Turbo cars are forged. How do you know they aren't?

I only think they are because so many people mention it so often..
When ordering replacement Mahle pistons all 99/900 applications are spec'd with cast pistons. As was pointed out, the stock boost levels do not warrant using a forged piece. The factory specs also list cast pistons as the only option for pistons.

james
team saabworks
Reply With Quote Quick reply to this message
  #20  
Old 6th July 2004
aeroman aeroman is offline
SaabNut!
 
Join Date: Jul 2002                                                
Location: Corsica/Paris
My Saabs: 900 T16s / 9.5 aero
Posts: 285
Default

I broke an engine because of detonation, the car was a 900 turbo 16 with just a 3.3fpr and a mbc (so the apc was disconected) the pressure of the turbo was about 1.25bar, I broke this engine at 220 km/h, I used to drive this car as a crazy guy. When I think about it I think that the pistons of the 900 are very strong!!

now my car is running with still the MBC and a very high boost pressure (1.5bar) but with lots of others mods to prevent detonation:

air/water intercooler
aquamist water injection and 1mm injectors
27lb/h injectors
3.3fpr
2.3 head cylinder

Now no problems and I am still runing it so hard!!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the SaabCentral Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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

Forum Jump


All times are GMT -4. The time now is 12:27 PM.



Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.

top of page | sitemap | email us



copyright © 2003 - 2011 saabcentral.com, All rights reserved http://www.whiter.co.uk - valid xhtml - valid css
SaabCentral is an independently run website and is not affiliated in any way to Saab Automobile AB.


Garage Plus vBulletin Plugins by Drive Thru Online, Inc.