Are the Ralliart 9.4:1 pistons any stronger than the std 9.0 pistons for NA or boosted use? I have read on forums that Pajero pistons are recommended as stronger than std 6G74 3.5 litre Magna ones. Does anyone know the compression ratio of the 3.5 lite Pajero pistons and the model they are from?

comp ratio is 10.0:1, and I believe they're from the 1993-99 DOHC 3.5L Pajero.

I dont know if they are any stonger, They good for raising compression and rather cheap.. I wouldnt use them for boosted use but NA would be fine..:)

comp ratio is 10.0:1, and I believe they're from the 1993-99 DOHC 3.5L Pajero.

Correct there wook, the 10:1 comp pajero pistons are from the NJ/NK 3.5 DOHC models 1993-1997

ACL piston assembly kit number for them is: 6MKRY8069

And as EGO has said for a NA application they are a good cheap set up but for boosted, forged are the way to go.

Regardless of compression ratio (within reason), as a general rule of thumb don't go past 7-8psi of boost on cast NA pistons. Though certain NA motors have been proven to be safe running more boost than this.

It's not just about the material used, but the actual design/shape of the piston.

9:1 regular magna pistons, 9.4:1 ralliart and 10:1 pajero pistons are most likely all ok for 7-8psi boost, provided the tune is detonation-free and runs sensible mixtures/timing for that particular application.

For over 7-8 psi boost you need aftermarket pistons designed for boost - i.e forged pistons with a chunky crown etc.

what sort of power increase would there be in using 10.0:1 compression pistons a normal 6G74 Magna engine

what sort of power increase would there be in using 10.0:1 compression pistons a normal 6G74 Magna engine
3/4 of sweet FA.
Just remember your ripping apart your motor (mmm expensive) to throw in pistons that with a tune might gain an extra 6kw. hardly worth the effort

Was waiting for something along these lines to come along after those ralliart pistons were posted in the ebay thread.

No point putting these in if you are chasing big power, if your going NA go either the Pajero pistons (10.0 compression) or the 11.1 out of a secret car

FI dont bother with either just get a set made by a piston mob down in melbourne they have the 9.0, 9.4 and 10.1 compression prints on the computer and can turn them out (some mob that did tzaboys and Stackies)

mmm 9.4 + 12psi mmmm tasty

mmm 9.4 + 12psi mmmm tasty
9.4 forged you mean, 9.4comp normal pistons wouldnt last a chance with 12psi!

']9.4 forged you mean, 9.4comp normal pistons wouldnt last a chance with 12psi!


naturally, :badgrin: :badgrin:

']9.4 forged you mean, 9.4comp normal pistons wouldnt last a chance with 12psi!

LOL my MPS3 only has "cast" 9.5:1 pistons from factory combined with 14.7psi stock boost (now running 19psi) but then again it does have knock sensors (and direct injection which is supposed to have a cooling effect on combustion) which helps a heap

See page 150 for 6MKRY8069 PISTON HEAD TYPE 4 (1995-on) 6MKRY8068 PISTON HEAD TYPE 8 (9/1995-on)

http://www.afabot.com/montero/fsm/acl_pistonproducts_pp99.pdf

ACL piston catalogue states:

ACL Duratech pistons are designed to provide enhanced performance characteristics compared to the OEM pistons they replace. These pistons are all solid skirt design which provides up to 30% greater strength than pistons which have a sawn or cast oil return slot in or below the oil ring groove. Oil drain back is via cast slots below the oil ring.
High silicon material: ACL Duratech¤ pistons are made from a high silicon aluminium alloy which is the same as used in most high performance original equipment pistons around the world. This alloy combines excellent scuff and wear properties with maximum strength and minimum expansion.
Benefits
• Stronger than the original equipment pistons they replace.
• Lighter than the original equipment pistons they replace hence less mechanical losses and maximum power and less vibration.
• Highly wear and scuff resistant in extreme situations due to high silicon alloy.
• Able to operate quietly and reliably at low clearance due to low expansion coefficient of the high silicon material and also due to sophisticated computer generated 3 dimensional diamond turned skirt profiles.

Automotive Components Limited
Level 8, 390 St Kilda Road
Melbourne Victoria
AUSTRALIA 3004
Telephone: 03 9285 4000
Facsimile: 03 9866 4300
Website: www.acl.com.au

State Offices: Brisbane 07 3365 0736
Sydney 02 9757 6139
Melbourne 03 9285 4000
Adelaide 08 8262 9100
Perth 08 9455 5444
Orders Phone: 1300 363 356
Orders Facsimile: 1300 363 357

ACL Piston Products
87 Mitchell Street
Maidstone Victoria 3012
Telephone: 03 9317 1888
Facsimile: 03 9317 3198
Website: www.acl.com.au
Technical Enquiries: 1800 033 113
(Division of Automotive Components Limited)
(A.C.N. 006 542 785)

TABLE OF CONTENTS

Important Notes & Product Information
- How To Use This Catalogue i.
- Product Abbreviations, Prefixes & Suffixes ii.- Piston Information & Skirt Grades iii.
- Piston Pin Fitting - Press Fit Applications iv.
- Piston Ring Information v.
- Cylinder Boring and Honing viii.
- Re-Ringing Information ix.
- Sleeve & Sleeve Assemblies xiv.
Index
- Vehicle Model/Engine Index xv.
ADDITIONAL INFORMATION AT REAR OF CATALOGUE
Numerical Listings
- Pistons 223
- Ring Sets 225
- Cylinder Sleeves 230
- Pistons By Bore Size 232
- Ring Sets By Bore Size 224
- Ring Sets By Bore & Ring Depth 237

i read an article somewhere that it is not neccesary to lower compression when turbo charging, and it listed some great points. ill try find it online,

i read an article somewhere that it is not neccesary to lower compression when turbo charging, and it listed some great points. ill try find it online,

maybe it depends on the original compression ratio though.

would the pajero pistons and a thicker head gasket survive a few more psi or still gonna blow em out the block?

Allot of it has to do with the precision of tuning, combustion chamber design etc....most new cars are fairly efficient and can handle a fair amount of boost on higher compression ratios, head designs are allot better these days, so allot less potential for hot spots. I've seen stock LS2s running 10psi with no problems on their factory 10.2:1 CR. From memory the BF XR6-T's ran a higher CR too.

Allot of it has to do with the precision of tuning, combustion chamber design etc....most new cars are fairly efficient and can handle a fair amount of boost on higher compression ratios, head designs are allot better these days, so allot less potential for hot spots. I've seen stock LS2s running 10psi with no problems on their factory 102:1 CR. From memory the BF XR6-T's ran a higher CR too.

Na all BA/BF XR6T's ran 8.7:1 comp, the new FG XR6T runs 8.8:1. Your thinking of the none turbo models which had there compression rasied from 9.3:1 (BA models) to 10.3:1 with the BF model.

i read an article somewhere that it is not neccesary to lower compression when turbo charging, and it listed some great points. ill try find it online,
Well it's not, but from what I understand if you put say 6psi of boost in a 10:1 engine compared to an 8:1, you'll make more power off the 10:1 but you can only go so much before you get knock.
I'm only going off stuff I have read about the 3L DOHC 3000GT motors. many people do TT conversions to NA motors and run about 6-12psi in them, but some run water/alki injection on top of that to keep heat down.

Na all BA/BF XR6T's ran 8.7:1 comp, the new FG XR6T runs 8.8:1. Your thinking of the none turbo models which had there compression rasied from 9.3:1 (BA models) to 10.3:1 with the BF model.

You're right, I thought both the turbo and NA models used the same CR.

If you are going to pull your engin apart to run hi comp pistons in an NA build, i would be doing a:

full rebuild
lightened cran
forged rods
some de shrouding around the valves in the heads
cams
inlet mods(twin t/b's)
other stuff

See page 150 for 6MKRY8069 PISTON HEAD TYPE 4 (1995-on) 6MKRY8068 PISTON HEAD TYPE 8 (9/1995-on)

http://www.afabot.com/montero/fsm/acl_pistonproducts_pp99.pdf

ACL piston catalogue states:

ACL Duratech pistons are designed to provide enhanced performance characteristics compared to the OEM pistons they replace. These pistons are all solid skirt design which provides up to 30% greater strength than pistons which have a sawn or cast oil return slot in or below the oil ring groove. Oil drain back is via cast slots below the oil ring.
High silicon material: ACL Duratech¤ pistons are made from a high silicon aluminium alloy which is the same as used in most high performance original equipment pistons around the world. This alloy combines excellent scuff and wear properties with maximum strength and minimum expansion.
Benefits
• Stronger than the original equipment pistons they replace.
• Lighter than the original equipment pistons they replace hence less mechanical losses and maximum power and less vibration.
• Highly wear and scuff resistant in extreme situations due to high silicon alloy.
• Able to operate quietly and reliably at low clearance due to low expansion coefficient of the high silicon material and also due to sophisticated computer generated 3 dimensional diamond turned skirt profiles.

ACL Performance Pistons & Rings ("9000" series part numbers)
ACL Performance and RACE brand piston assemblies are available for a number of popular engines. These are made from high silicon aluminium alloy and are heat treated to T5+T6 solution treatment specification. They are of solid skirt design and therefore much stronger than the standard pistons they replace. They are also considerably lighter and in addition have tapered alloy steel pins for further weight reduction.Other special features include a pressure balancing groove in-between the top and second compression ring grooves, higher compression ratio (in most cases), solid pin boss design, and diamond turned skirt shape featuring compound ovality and vertical profiles. These enable the pistons to operate at much lower clearance than most forgings.
ACL Performance pistons are NOT intended to replace forged pistons in applications where output is greater than 100 BHP/litre or in turbocharged and supercharged engines. However they are ideal for engine builders wishing to obtain moderate increases in power and speed from otherwise standard engines for street or off road use.
Special rings are specified for most of these pistons and have molybdenum inlaid high strength SG iron top rings and low friction oil rings. In most cases the rings are unique to these pistons and are supplied as part of the piston assembly. File back top rings are available for most applications for specialist engine builders.
Pistons and rings with 9000 series part numbers in this catalogue (except 9079, 9080, 9094 and 9104) are for performance applications. (See illustrations in application listing of catalogue).
Benefits
• Less weight: reduces loads and friction and enables higher RPM, more power.
• Less vibration (V8 crankshafts will need to be balanced to suit).
• Extremely robust design: Allows higher compression and higher speeds.
• Quiet operation due to ability to run low clearance. Also less bore loading.
• Optimum ring sealing at high RPM due to pressure balancing groove feature.
• Reduced blowby especially with optional file back rings.



Automotive Components Limited
Level 8, 390 St Kilda Road
Melbourne Victoria
AUSTRALIA 3004
Telephone: 03 9285 4000
Facsimile: 03 9866 4300
Website: www.acl.com.au

State Offices: Brisbane 07 3365 0736
Sydney 02 9757 6139
Melbourne 03 9285 4000
Adelaide 08 8262 9100
Perth 08 9455 5444
Orders Phone: 1300 363 356
Orders Facsimile: 1300 363 357

ACL Piston Products
87 Mitchell Street
Maidstone Victoria 3012
Telephone: 03 9317 1888
Facsimile: 03 9317 3198
Website: www.acl.com.au
Technical Enquiries: 1800 033 113
(Division of Automotive Components Limited)
(A.C.N. 006 542 785)

TABLE OF CONTENTS

Important Notes & Product Information
- How To Use This Catalogue i.
- Product Abbreviations, Prefixes & Suffixes ii.- Piston Information & Skirt Grades iii.
- Piston Pin Fitting - Press Fit Applications iv.
- Piston Ring Information v.
- Cylinder Boring and Honing viii.
- Re-Ringing Information ix.
- Sleeve & Sleeve Assemblies xiv.
Index
- Vehicle Model/Engine Index xv.
ADDITIONAL INFORMATION AT REAR OF CATALOGUE
Numerical Listings
- Pistons 223
- Ring Sets 225
- Cylinder Sleeves 230
- Pistons By Bore Size 232
- Ring Sets By Bore Size 224
- Ring Sets By Bore & Ring Depth 237

Might as well throw most of that info out as ACL wont/dont do the 9000 series in anything that suits a magna