s4 vs. s5 turbo
Thread Starter
exhaust leak
Joined: Jun 2009
Posts: 207
Likes: 4
From: peterborough, ontario
s4 vs. s5 turbo
hey guys, i've tried searching for a while. just wondering what the difference is between the s4 stock turbo and the s5 stock turbo.
i've heard the s4's are better? i'm putting it on a first gen.
thanks
i've heard the s4's are better? i'm putting it on a first gen.
thanks
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
rear turbine housing is individually fed genuine twin scroll on s5
s4 is open collector, but has a "scroll" control flap that will shut 1 half of the turbine off to aid in low down spool
this is part of the oem turbo manifold ,, which, where i come from cant be used in 1st gen due to steering box location
( in RHD 1st gens with s4 you often have to use an aftermarket turbo manifold which will negate the scroll control )
i had to choose i would err s5,, less of a handbrake up top , with minimal cost down low compared to a s4 without scroll control
asides the turbine housing and wastegate can, s4 and s5 turbos have identical front and rear wheels
( very early 1986 s4 turbos have a double heat shield and a different height step on the CHRA to mount the turbine cover to,, later s4 the CHRA is identical to s5 )
s4 is open collector, but has a "scroll" control flap that will shut 1 half of the turbine off to aid in low down spool
this is part of the oem turbo manifold ,, which, where i come from cant be used in 1st gen due to steering box location
( in RHD 1st gens with s4 you often have to use an aftermarket turbo manifold which will negate the scroll control )
i had to choose i would err s5,, less of a handbrake up top , with minimal cost down low compared to a s4 without scroll control
asides the turbine housing and wastegate can, s4 and s5 turbos have identical front and rear wheels
( very early 1986 s4 turbos have a double heat shield and a different height step on the CHRA to mount the turbine cover to,, later s4 the CHRA is identical to s5 )
Thread Starter
exhaust leak
Joined: Jun 2009
Posts: 207
Likes: 4
From: peterborough, ontario
i have a 12a so i won't be using the 13b exhaust mani. and its a north american car so steering box is on the left side.
Does anyone have any specs on either of the turbos? AR, Trim, exhaust diameter, inlet dia etc
Does anyone have any specs on either of the turbos? AR, Trim, exhaust diameter, inlet dia etc
http://www.ausrotary.com/viewtopic.php?f=53&t=157720
Scroll closer to the bottom and he covers s4 & s5 turbos. pretty helpful thread.
Scroll closer to the bottom and he covers s4 & s5 turbos. pretty helpful thread.
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
/\
Originally Posted by bumpstart
the turbos--
where do i start? i am completely unfamiliar to the FC turbo !
LOL
all are Hitachi HT-18-2S, but often referred to as HT-18S
s4 types -
early s4 86/87 HT18S-2SC N31813700C ( small banjos, deep recess cartridge lip and volute )
later s4 87/88 and vert HT18S-2SE N34413700
Luce HT18S-2SD N33713700A
s5 types -
s5 HT18S-2SF N37013700
later s5 and vert HT18S-2SG N37813700
to be honest, you cant pick them from another by eye, just s4 early/ late and s5
- i have only ever seen one change in rear wheel/ shaft and compressor profile turbo to turbo
( i suspect it was a jap rework as the nut was reverse thread !! = signature from 1 jap turbo manufacturer )
these HT-18s-2s have a water cooled core
which is mazda division 5/ hitachi patent evolution developed from the non water cooled Garrett T03/ T04B parts bin
( journal size/ parts , thrust bearing, backing plate, spider washer and carbon seal )
the compressor and exhaust wheels and volute profiles are Hitachi unique, specially for Mazda
hence, people find that Garrett T3/T4 series parts and kits interchange to some extent
s5 and s4 differ in rear volute only, s5 being split pulse entry from the OEM manifold , with twin waste-gate flap the result
s4 feature the scroll can and flap
speaking directly on the s4 twin scroll theory -
which down low closes one half of the asymmetric entry paired openings
generally, the s4 and s5 rear turbine volutes and waste-gate can can interchange
though very early s4 have small water banjo fittings, and a deeper cartridge step for the turbine volute
this can be engineered around !
s4 block has a "twin scroll" pneumatic gate as well as the similar looking waste-gate actuator
( and a birds nest to suit )
that's the ugly big can attached to the s4 turbo manifold on the bench
the s5 turbo ( left ) is a conventional enough square base on the turbine volute
s5 block has a boost control solenoid on the filler pipe ( of all places ! )
the s4 turbo foot ( right ) is asymmetric in pattern
the s5 has an obviously larger rear plate than the s4 units on the right
and that's why, twin waste-gate flap in the s5
i have overlaid the s4 turbo over the top of the s5 volute
where do i start? i am completely unfamiliar to the FC turbo !
LOL
all are Hitachi HT-18-2S, but often referred to as HT-18S
s4 types -
early s4 86/87 HT18S-2SC N31813700C ( small banjos, deep recess cartridge lip and volute )
later s4 87/88 and vert HT18S-2SE N34413700
Luce HT18S-2SD N33713700A
s5 types -
s5 HT18S-2SF N37013700
later s5 and vert HT18S-2SG N37813700
to be honest, you cant pick them from another by eye, just s4 early/ late and s5
- i have only ever seen one change in rear wheel/ shaft and compressor profile turbo to turbo
( i suspect it was a jap rework as the nut was reverse thread !! = signature from 1 jap turbo manufacturer )
these HT-18s-2s have a water cooled core
which is mazda division 5/ hitachi patent evolution developed from the non water cooled Garrett T03/ T04B parts bin
( journal size/ parts , thrust bearing, backing plate, spider washer and carbon seal )
the compressor and exhaust wheels and volute profiles are Hitachi unique, specially for Mazda
hence, people find that Garrett T3/T4 series parts and kits interchange to some extent
s5 and s4 differ in rear volute only, s5 being split pulse entry from the OEM manifold , with twin waste-gate flap the result
s4 feature the scroll can and flap
speaking directly on the s4 twin scroll theory -
Originally Posted by Jack K. Yamaguchi
The 11 blade turbine, of impact design, is 64 mm (2.52 inch) in diameter.
It’s scroll area, the path for exhaust gas, is divided into two passages separated by an integrally cast wall;
one, called the secondary scroll, has a trap-door-like gate operated by intake vacuum.
The turbine thus has two cross sectional area (a) factors
A being the scroll’s smallest area as used in calculating turbocharger performance characteristics:
6.00 sq. cm (.93 sq. in) for the primary path and 9,48 sq. cm (1.47 sq. in) for the secondary.
The other factor is R, the distance between the turbine-shaft center and the center of area
R: 59.4 mm (2.34in) for the primary path, 60.4 mm (2.38in) for the secondary.
Thus the twin-scroll turbocharger has two A/R ratios:
0.4 for the primary and 1.0 for the primary and secondary combined.”
As for the compressor side, “its 12-blade compressor is 63 mm (2.48 in) in diameter.
It’s scroll area, the path for exhaust gas, is divided into two passages separated by an integrally cast wall;
one, called the secondary scroll, has a trap-door-like gate operated by intake vacuum.
The turbine thus has two cross sectional area (a) factors
A being the scroll’s smallest area as used in calculating turbocharger performance characteristics:
6.00 sq. cm (.93 sq. in) for the primary path and 9,48 sq. cm (1.47 sq. in) for the secondary.
The other factor is R, the distance between the turbine-shaft center and the center of area
R: 59.4 mm (2.34in) for the primary path, 60.4 mm (2.38in) for the secondary.
Thus the twin-scroll turbocharger has two A/R ratios:
0.4 for the primary and 1.0 for the primary and secondary combined.”
As for the compressor side, “its 12-blade compressor is 63 mm (2.48 in) in diameter.
generally, the s4 and s5 rear turbine volutes and waste-gate can can interchange
though very early s4 have small water banjo fittings, and a deeper cartridge step for the turbine volute
this can be engineered around !
s4 block has a "twin scroll" pneumatic gate as well as the similar looking waste-gate actuator
( and a birds nest to suit )
that's the ugly big can attached to the s4 turbo manifold on the bench
the s5 turbo ( left ) is a conventional enough square base on the turbine volute
s5 block has a boost control solenoid on the filler pipe ( of all places ! )
the s4 turbo foot ( right ) is asymmetric in pattern
the s5 has an obviously larger rear plate than the s4 units on the right
and that's why, twin waste-gate flap in the s5
i have overlaid the s4 turbo over the top of the s5 volute
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Thread Starter
exhaust leak
Joined: Jun 2009
Posts: 207
Likes: 4
From: peterborough, ontario
This is really helpful. also the Fc3spro.com has an awesome data sheet of turbo specs. its a must look at for anyone looking at swapping turbos. too bad there wasn't any compressor eff. maps.
Thanks guys for posting
Thanks guys for posting
I just ran into this with my hybrid. The early S4 CHRA can't be dropped into an S5 turbine housing without first ditching the extra heatshield. The recess in the early S4 turbine housing is 1mm deeper (the thickness of the heatshield).
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