ARP Head Stud
22 September 2010, 03:57 PM
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ARP Head Stud
What can the 11mm ARP Head Stud take in terms of boost and power?
Is it really worth paying for the 14mm conversion which some builders offer?
Cheers
Is it really worth paying for the 14mm conversion which some builders offer?
Cheers
22 September 2010, 05:29 PM
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Cosworth high tensile variant would be the better option if you don’t want to splash out on the 14mm conversion but want a more than the 11mm APRs have to offer.
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22 September 2010, 06:47 PM
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2.1 CDB Stroker.
I don't mind spending the money if it's definitely needed!? As eventually I will hopefully be going over 500.
I don't mind spending the money if it's definitely needed!? As eventually I will hopefully be going over 500.
22 September 2010, 06:54 PM
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enginertuner(alan) recommended the 11mm to me for my 2.1 stroker above the expensive 14mm headstud conversion however i've no idea of the power they can handle!!
22 September 2010, 08:15 PM
#12
im not 100% but over 500 would require 14mm conversion to both block and heads, expensive - yes, but if you going 500plus, im sure you have the dollars as its not cheap to hit that target anyways lol
22 September 2010, 08:26 PM
#13
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You can go way beyond 500bhp on a 2.5 for instance on ARP 11mm headbolts and Cometic gaskets.... the question is how much boost are you running and how much abuse do you give your engine, dictates how long the gaskets will last (assuming the engine has been built correctly). Mine lasted 9k of proper abuse at over 500bhp and with boost up to 2.5bar, but mostly at over 2bar.
However.... on a 2.1 you would have more meat around the tops of the cylinders and although the same issues *may* apply, I suspect the 2ltr / 2.1ltr or 2.2 blocks are the better choice in that area.
If I did this all again I would probably go with the Cosworth High Tensile bolts and Cosworth stopper Headgaskets on a 2.1 stroker, which is the set-up I moved to on my 2.5 build with the previous Spec C.
Keeping boost at sensible levels helps.
However.... on a 2.1 you would have more meat around the tops of the cylinders and although the same issues *may* apply, I suspect the 2ltr / 2.1ltr or 2.2 blocks are the better choice in that area.
If I did this all again I would probably go with the Cosworth High Tensile bolts and Cosworth stopper Headgaskets on a 2.1 stroker, which is the set-up I moved to on my 2.5 build with the previous Spec C.
Keeping boost at sensible levels helps.
22 September 2010, 10:28 PM
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22 September 2010, 10:30 PM
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23 September 2010, 10:30 AM
#19
I am still on 11mm ARP's on my drag car, so 682bhp and 2.26 bar ! I am due to refresh this winter and I will use the Cosworth 260,000 11mm's. Just need to find some, no one seems to have them in stock.
However I will add in two years on this build most work has been drag, it did do a few track days @ circa 550bhp with no issues and Scoobysprint last season at 600bhp.
However I will add in two years on this build most work has been drag, it did do a few track days @ circa 550bhp with no issues and Scoobysprint last season at 600bhp.
23 September 2010, 10:56 AM
#20
http://cgi.ebay.co.uk/Cosworth-Head-...item483ba5d493
...Are these suitable? Or do they only fit 2.5L heads and/or blocks?
Last edited by joz8968; 23 September 2010 at 10:59 AM.
24 September 2010, 07:00 AM
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Cheers for the advice guys I probably will got for the 14mm conversion as I will probably always be pushing for more power.
I probably will got for the 14mm conversion as I will probably always be pushing for more power.
23 October 2019, 08:09 AM
#25
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I know this is an old topic, but a very interesting read. I wonder if any of the thought process has changed from hands on experience with the builds over the past 9 years.
On the 2.5L I've been told it's all about Boost / CFM / Torque as to how much of a safety margin you have before head lift and that 11mm ARP very much have their limitations. 610NM torque or 450 Ft-lbs and you can expect to be lifting your heads on 11mm at least in the experience of this particular Subaru engine builder who prefers to remain on the cautious side as ultimately it's us paying for rebuilds not them!
On the 2.5L I've been told it's all about Boost / CFM / Torque as to how much of a safety margin you have before head lift and that 11mm ARP very much have their limitations. 610NM torque or 450 Ft-lbs and you can expect to be lifting your heads on 11mm at least in the experience of this particular Subaru engine builder who prefers to remain on the cautious side as ultimately it's us paying for rebuilds not them!
23 October 2019, 03:13 PM
#27
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Fair point, what torque are you running and what turbo / boost. I followed the thread about ARP, Cosworth high tensile and importance of how they are torqued.
23 October 2019, 06:56 PM
#28
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low boost at min, around 1.3bar on an sc46x so only 380/390, once i have front mount and replaced exhaust manifold will be pushed to full potential so to 500+
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23 October 2019, 10:02 PM
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