944 S head prepared for 2.5liter turbo engine
07-11-2014, 04:03 PM
#91
Formula One Spin Doctor
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My main goal was to use (cheap) stock bottom end and that means 2.5 liter. Any modifications like sleeving the block etc would make the engine immediately hi-budget. 
Sweeet, no heat shielding ..... ?
Nothing special: stock 2.5liter crank and block, RARST factory forged rods, machined 951 pistons, stainless steel valves, S2 cams, ceramic coated exhaust ports (inside the head) and exhaust manifold (outside), Holset HE341 turbocharger (9 cm2 turbine, compressor is good to ~500-550 hp), custom intake manifold, custom intercooler made from two 951 cores, Siemens 870cc injectors, VEMS ECU, Spec Stage 4 clutch, S2 tranny with Torsen diff.
Will be resting in this '83 924 (has 951 brakes, alloy arms, Koni Yellows etc):
Will be resting in this '83 924 (has 951 brakes, alloy arms, Koni Yellows etc):
07-12-2014, 08:26 PM
#92
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Really interested to know what you used on the fuel rail. I'm in the middle of a 16v 2.5 liter build. It looks like the FPR is different on the 16v rail, so how does one go about sourcing a proper 3 bar unit. Can you adapt a standard 951 3 bar unit, or do you just reuse the S 3.8 bar unit? does it do ok with boost being added? What about the pressure dampner? I run without one on my 8v 951, can the lines be looped and the FPD be deleted with the 16v rail? Possible to reuse 8v fuel lines? Also I'm wondering how you made the fixture to flycut the 951 pistons, as this is the route I will be taking as well. How deep did your reliefs end up being? I'll be using stock S valves.
Last edited by Dougs951S; 07-12-2014 at 09:41 PM.
07-13-2014, 12:02 PM
#93
Three Wheelin'
Thread Starter
I use stock S2 rail, it has standard FPR fitment (with O-ring to the rail) and I use some BMW 3.0 bar unit. 944S 3.8bar unit could be easily used with boost, works like a regular 1:1 FPS should work. No problems with fuel supply until some very serious fuel demands as stock FPR's have smallish connections and when fuel demand is low the pressure will rise on the rail but not a concern with my goals..
I ditched the dampener and the return pipe just left disconnected.
Regarding valve reliefs, I left them just as stock 944S pistons.
Heat shielding is not present because I have not fabricated the pipes yet. All will be there before I install the engine.
Just for information, in case anyone plans to use early block with 16v head and wants to go wider timing belt, some mods are necessary: 1. Take S or S2 tensioner and remove the toothed gear from the bearing and install it onto early tensioner bearing (remove old one first). This is because there is no wider tensioner that would fit to early block.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
I ditched the dampener and the return pipe just left disconnected.
Regarding valve reliefs, I left them just as stock 944S pistons.
Heat shielding is not present because I have not fabricated the pipes yet. All will be there before I install the engine.
Just for information, in case anyone plans to use early block with 16v head and wants to go wider timing belt, some mods are necessary: 1. Take S or S2 tensioner and remove the toothed gear from the bearing and install it onto early tensioner bearing (remove old one first). This is because there is no wider tensioner that would fit to early block.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
07-13-2014, 04:36 PM
#94
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I use stock S2 rail, it has standard FPR fitment (with O-ring to the rail) and I use some BMW 3.0 bar unit. 944S 3.8bar unit could be easily used with boost, works like a regular 1:1 FPS should work. No problems with fuel supply until some very serious fuel demands as stock FPR's have smallish connections and when fuel demand is low the pressure will rise on the rail but not a concern with my goals..
I ditched the dampener and the return pipe just left disconnected.
Regarding valve reliefs, I left them just as stock 944S pistons.
Heat shielding is not present because I have not fabricated the pipes yet. All will be there before I install the engine.
Just for information, in case anyone plans to use early block with 16v head and wants to go wider timing belt, some mods are necessary: 1. Take S or S2 tensioner and remove the toothed gear from the bearing and install it onto early tensioner bearing (remove old one first). This is because there is no wider tensioner that would fit to early block.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
I ditched the dampener and the return pipe just left disconnected.
Regarding valve reliefs, I left them just as stock 944S pistons.
Heat shielding is not present because I have not fabricated the pipes yet. All will be there before I install the engine.
Just for information, in case anyone plans to use early block with 16v head and wants to go wider timing belt, some mods are necessary: 1. Take S or S2 tensioner and remove the toothed gear from the bearing and install it onto early tensioner bearing (remove old one first). This is because there is no wider tensioner that would fit to early block.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
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Jay Wellwood (10-14-2023)
07-16-2014, 07:19 AM
#98
Just for information, in case anyone plans to use early block with 16v head and wants to go wider timing belt, some mods are necessary: 1. Take S or S2 tensioner and remove the toothed gear from the bearing and install it onto early tensioner bearing (remove old one first). This is because there is no wider tensioner that would fit to early block.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
2. You need 1 tooth longer timing belt than stock S2/S/968 119teeth belt as the tensioner position is slightly different. 120x25.4mm belt is correct, from VW 2.4 diesel engine, same as found on Volvo 940/960's.
07-16-2014, 07:28 AM
#99
Three Wheelin'
Thread Starter
I used eccentric of the early tensioner and pressed later wide roller onto the early eccentric.
BTW, the Gates part number for the longer belt is 5398XS.
BTW, the Gates part number for the longer belt is 5398XS.
07-16-2014, 08:02 AM
#100
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Is that only required for pre 85.5 blocks? I'm assuming with an 86 turbo block I can just swap in the two 16v timing belt rollers and swap to the 16v auto spring tensioner?
07-16-2014, 03:10 PM
#105
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You said this was if you "wanted" to go with the wider belt, can you reuse the 8v rollers and belt if you have an early block with the eccentric tensioner?