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Cheap bottom end upgrades?
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1885
Location: Somerset, UK

PostPosted: Fri Sep 27, 2019 7:22 am    Post subject: Reply with quote

Juho wrote:
https://racingfuel.es/head-stud-kit-porsche-924-20-all-models-arp-complete-head-studs-n1?lang=en

Has anyone ordered from this site?


Canít find the part number, but I used ARP studs listed for Escort/Sierra Cosworth engines from a Ford specialist which were nearly half that price.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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safe  



Joined: 18 Mar 2017
Posts: 122
Location: Sweden

PostPosted: Fri Sep 27, 2019 7:26 am    Post subject: Reply with quote

I really don't see a need for arp head studs in an NA application.
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Juho  



Joined: 03 Oct 2018
Posts: 72
Location: Finland

PostPosted: Fri Sep 27, 2019 7:42 am    Post subject: Reply with quote

Carrera RSR wrote:
Juho wrote:
https://racingfuel.es/head-stud-kit-porsche-924-20-all-models-arp-complete-head-studs-n1?lang=en

Has anyone ordered from this site?


Canít find the part number, but I used ARP studs listed for Escort/Sierra Cosworth engines from a Ford specialist which were nearly half that price.


ARP 251-4701? found this part number on ideola's garage website
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Juho  



Joined: 03 Oct 2018
Posts: 72
Location: Finland

PostPosted: Fri Sep 27, 2019 8:21 am    Post subject: Reply with quote

safe wrote:
I really don't see a need for arp head studs in an NA application.


Arps would be obviously better but i think im going with elrings since they cost so much less
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 848
Location: Maysville, Colorado

PostPosted: Wed Oct 02, 2019 11:34 pm    Post subject: Reply with quote

The ARP head studs are for a Ford Sierra Cosworth #251-4701 and are $135 from Summit racing or maybe 110E. The crankscraper guy is an absolute ripoff, I ordered and paid for two, got one. When I last checked he was not very healthy. Maybe a change by now.

When porting manifolds make your own gasket patterns, the gaskets are too big. enlarging to the gasket will make the air slow down then re accelerate. If using the stock CI exhaust manifold, grind it out to smooth it and match the head and header. It is a very poor and rough casting and very hard cast iron. Between 77 and 78 they added another cooling fin to the casting as my '77 did crack.

My 10+ CR race motor with mild cam, MSDS header and webers is at an entire different performance level, even with just guessing the proper carb jetting and timing.
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Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
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Juho  



Joined: 03 Oct 2018
Posts: 72
Location: Finland

PostPosted: Thu Oct 03, 2019 12:25 am    Post subject: Reply with quote

MikeJinCO wrote:
The ARP head studs are for a Ford Sierra Cosworth #251-4701 and are $135 from Summit racing or maybe 110E. The crankscraper guy is an absolute ripoff, I ordered and paid for two, got one. When I last checked he was not very healthy. Maybe a change by now.

When porting manifolds make your own gasket patterns, the gaskets are too big. enlarging to the gasket will make the air slow down then re accelerate. If using the stock CI exhaust manifold, grind it out to smooth it and match the head and header. It is a very poor and rough casting and very hard cast iron. Between 77 and 78 they added another cooling fin to the casting as my '77 did crack.

My 10+ CR race motor with mild cam, MSDS header and webers is at an entire different performance level, even with just guessing the proper carb jetting and timing.


how much power you think your engine is making with those mods?
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 848
Location: Maysville, Colorado

PostPosted: Thu Oct 03, 2019 4:03 am    Post subject: Reply with quote

I have no idea as to power, the car is probably 150-200kg lighter also. It is so different it is unbelievable, when accelerating in 3rd you get shoved back in the seat a bit,not the sedate acceleration as in a stock one. Since I think my street car has a blown head gasket it will get a Cometic head gasket and ARP studs when it goes back together, it is just better made parts. The old bolts are 40 years old and the new ones may be Chinese junk, having worked in the piston ring industry, aftermarket even brand name parts(particularly obsolete ones) basically have no quality control. It may cost more, but you only have to do it once. Also getting a thinner Cometic head gasket(.040 vs .065) increases the CR. I think it will be necessary to pull the hood using the ARP studs.
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Poco a Poco, #033 '78 Vintage racer, SCCA Dp-81
'77 924
cricketdesigns.com
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daniel  



Joined: 18 Jun 2009
Posts: 620
Location: Sydney, Australia

PostPosted: Tue Oct 15, 2019 12:01 pm    Post subject: Reply with quote

My motor has 125rwhp (probably 150-160 at flywheel) with the following mods:
- Mild Cam (30/70 from paeco)
- Standard turbo head, valves and springs
- Cometic head gasket to give 11:1 compression
- custom forged flat top pistons
- polished rods (to remove weight)
- lightened flywheel
- bottom end balanced and blue printed
- basic port and polish job of head and inlet
- home made mandrel bend exhaust (not equal length due to RHD car and steering column interference)


10 years racing with only oil changes.
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1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet
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