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RSR enducate me please.
I was watching youtube videos of the old 74 RSR, such a nasty lil motor. THese made like 330-350HP if I am correct?
They did this with 10.3 comp? 2 valve heads, and pretty stout cams... What am I missing, because most 3.0 in street versions like the SC, struggle to get over 200hp I'm sure there is some exotic costy bits I just don't know about hiding inside the RSR |
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08-08-2019, 06:16 PM
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Join Date: Jun 2008
Posts: 100
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Edit: realized you mean the 3.0 74 not the 2.8.
It revs to 8000rpm. 280hp. More rpm, more hp. https://www.roadandtrack.com/car-culture/a8581/1973-porsche-911-carrera-rsr-data-panel/ Last edited by evilfij; 08-08-2019 at 06:27 PM.. |
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08-08-2019, 06:21 PM
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Registered
Join Date: May 2004
Location: Boulder, Colorado
Posts: 7,275
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I don't know about 350, but Anderson lists one at 330. These motors had larger ports, intakes and exhausts to go with them, slide valve MFI, and most likely titanium rods to help them live reving over 8,000. 8,000 is listed as peak HP, but you upshift above peak HP, so maybe 8,500 - it is really based on the shape of the torque curve. And, of course, cams.
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08-08-2019, 07:07 PM
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Functionista
Join Date: Jul 2011
Location: CO
Posts: 7,717
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You are missing the fact that they had to be torn down every 40-50 hours vs 100-200K miles for road cars.
__________________
Jeff 74 911, #3 I do not disbelieve in anything. I start from the premise that everything is true until proved false. Everything is possible. |
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08-08-2019, 07:33 PM
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Registered
Join Date: Sep 2015
Location: Costa Rica and Pennsylvania U.S.
Posts: 3,301
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Rsr
Lots of nuances with these motors.I have repaired a number of them.10.3 was for customer motors.Factory team motors were 12.5 to 1.Different piston called ROITMEIR on the Mahle box.I bought a few sets from Charly Spira in the early 90,s.You make the good power with the heads and these were very special.Intake & exhaust ports were 43mm to match the 43mm slidevalve intake.Intake valves were flat top & sodium filled.Rocker arms were 80 grams with lash caps where standard cast rockers are about 120 grams.Crank was 25 lbs where an SC 3.0 is about 31 lbs.Motors with steel rods used the 917 rod bolt which was titanium and reusable.Factory team motor rods were titanium.Andial used Del West Ti valves in their motors but the keeper grooves would wear out.They used stock springs but carefully matched.I have done comparison flow checks and the RSR head is like wow.Those guys were good.Best starting comparison now would be a 3.2 head.Bill at Extreme makes them sing.I use a set of the 12.5 Mahles in my 2.8 short stroke but with longer Ti rod makes even more compression.Dick Elvirude built a 3.0 for Monte Shelton that spun very high and made a little over 400 hp.Ciao Fred
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08-09-2019, 02:15 AM
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Thats the info I was looking for... I knew they were special I just wasn't sure what the sauce was.
That light crank must make that things spin like crazy, my lil 3.0SC is a rev happy lil thing. |
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08-09-2019, 07:57 AM
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