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deanbradford
Samba Member
Joined: October 30, 2013
Posts: 34
Location: United Kingdom
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 Posted: Sat Jan 13, 2018 2:16 am Post subject: 2276 CR |
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I'm building a 2276 engine which will be using an Engle FK10 camshaft.
Apparently they need a compression ratio of between a 9.5 and 10:1
Using the CB Performance engine calculator my current set up has a compression ratio of 9.3 based on the following info.
My question is the extra cost of sending the heads away to be machined will be around £150 - £200 but with such a small difference in CR is it going to make much different in engine performance?
Engine Bore 94mm
Engine Stroke 82mm
Deck Height 1mm
Combustion Chamber CC's 62
Your Compression Ratio is 9.3
Your Displacement: 2276
Cheers
Dean |
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66brm
Samba Member
Joined: January 25, 2010
Posts: 3676
Location: Perth Western Australia
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| Posted: Sat Jan 13, 2018 2:52 am Post subject: Re: 2276 CR |
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What's it going to be fitted to? Exhaust? Intake?
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| modok wrote: |
| I am an expert at fitting things in holes, been doing it a long time |
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Vanillagurilla
Samba Member
Joined: November 21, 2017
Posts: 1061
Location: California
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| Posted: Sat Jan 13, 2018 3:03 am Post subject: Re: 2276 CR |
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| Remember that you can always add shims or copper head spacers to lower compression so I would have them cut. 56cc will give you 10:1, maybe go to 55cc and add a 0.010 shim. |
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deanbradford
Samba Member
Joined: October 30, 2013
Posts: 34
Location: United Kingdom
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| Posted: Sat Jan 13, 2018 3:41 am Post subject: Re: 2276 CR |
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Heads are CB Performance Ultra Mag Plus 044 cnc ported 37.5 x 42mm with Match ported manfnifolds with Weber IDF carbs.
Exhaust is merged 1 3/4 inch.
Heads are already 62 cc
Cheers
Dean |
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66brm
Samba Member
Joined: January 25, 2010
Posts: 3676
Location: Perth Western Australia
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| Posted: Sat Jan 13, 2018 4:05 am Post subject: Re: 2276 CR |
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How much street VS strip are you looking at doing? I would certainly be looking at bumping it up for a hot street and strip car
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Aust. RHD 66 Type 1
Aust. RHD 57 Type 1 Oval
| modok wrote: |
| I am an expert at fitting things in holes, been doing it a long time |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Sat Jan 13, 2018 5:57 am Post subject: Re: 2276 CR |
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Hey Dean, I run the FK10 in my 2276cc and only have 8.5 cr ,,But,,
It's turboed 
but off boost it's fine so,,my point is I would run 9.3 in a Heartbeat  for the 200 quid  they want ain't worth messin with mate 
unless your racing and need the last bit of Horsepower to win 
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Alstrup
Samba Member
Joined: July 12, 2007
Posts: 7219
Location: Videbaek Denmark
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| Posted: Sat Jan 13, 2018 6:07 am Post subject: Re: 2276 CR |
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Ahh, welcome to the variety of opinions. I am of the exact opposite opinion. An FK10 NEEDS about 10-1 to make the engine work properly. With say 9-1 it will run ok, but it will be rather "revy". The lower to midrtange torque will suffer. Give it 10-1 and the engine really wakes up. also, with 10-1 it´ll even run on 95 octane fuel.
Don´t shim the cylinders. 1 mm deck is in the perfect zone.
T |
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deanbradford
Samba Member
Joined: October 30, 2013
Posts: 34
Location: United Kingdom
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| Posted: Sat Jan 13, 2018 8:51 am Post subject: Re: 2276 CR |
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Interesting points of view. Bug is a weekender.
I’ve got a Autolinea alloy case. Wouldn’t it run a bit hotter with a 10:1 cr? |
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norris
Samba Member
Joined: November 25, 2009
Posts: 501
Location: Texas
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| Posted: Sat Jan 13, 2018 9:01 am Post subject: Re: 2276 CR |
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| My cam is a K8 and run a 9.3cr......works very well with 91 octane and 30* advance on a .010 in my 2276 |
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jpaull
Samba Member
Joined: February 22, 2005
Posts: 3466
Location: Paradise, Ca
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| Posted: Sat Jan 13, 2018 9:35 am Post subject: Re: 2276 CR |
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Alstrups advice is saving you, its a really good point.
With that cam the valves are open long enuff that you need more compression to equal what other guys (with less duration)are doing with less compression.
54 degrees of overlap. Thats a long time hangin both valves open loosin compression.
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Transmission by MCMScott:
Rhino case, Klinkenberg 4.12, Superdiff, 002 mainshaft with 091 first idler. Weddle 1.48 Third & 1.14 Fourth. |
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jfats808
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Joined: December 10, 2007
Posts: 5022
Location: oahu hawaii
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| Posted: Sat Jan 13, 2018 9:53 am Post subject: Re: 2276 CR |
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62 cc is their stock ported cc on 044s. Sounds like you ordered the heads without setting up the dh to see what you needed prior. 10 to 10.5 CR imo. Send the heads and get them cut to the target cc's you need. Chalk it up as a learning lesson.
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74 Thing
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Joined: September 02, 2004
Posts: 7394
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| Posted: Sat Jan 13, 2018 9:58 am Post subject: Re: 2276 CR |
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| Do it right the first time and send them out to have them cut or you will always wonder what if!!! |
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FreeBug
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Joined: March 12, 2012
Posts: 4278
Location: deepest, darkest Switzerland
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| Posted: Sat Jan 13, 2018 10:31 am Post subject: Re: 2276 CR |
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| jpaull wrote: |
Alstrups advice is saving you, its a really good point.
54 degrees of overlap. Thats a long time hangin both valves open loosin compression. |
I just don't see how you're loosing compression as the piston is essentially at TDC...
Loosing charge out the exhaust, or getting the charge diluted by exhaust, sure; but I just don't see how you "lose compression" when there isn't any to lose?
This in no way negates any of Alstrup's or your advice, just a side-comment. |
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ps2375
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Joined: April 24, 2014
Posts: 2471
Location: Meridian,ID
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| Posted: Sat Jan 13, 2018 10:41 am Post subject: Re: 2276 CR |
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| FreeBug wrote: |
| jpaull wrote: |
Alstrups advice is saving you, its a really good point.
54 degrees of overlap. Thats a long time hangin both valves open loosin compression. |
I just don't see how you're loosing compression as the piston is essentially at TDC...
Loosing charge out the exhaust, or getting the charge diluted by exhaust, sure; but I just don't see how you "lose compression" when there isn't any to lose?
This in no way negates any of Alstrup's or your advice, just a side-comment. |
Static CR vs. Dynamic CR, read up on it, many an interesting read. |
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richierich
Samba Member
Joined: December 23, 2004
Posts: 889
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| Posted: Sat Jan 13, 2018 11:53 am Post subject: Re: 2276 CR |
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| deanbradford wrote: |
Interesting points of view. Bug is a weekender.
I’ve got a Autolinea alloy case. Wouldn’t it run a bit hotter with a 10:1 cr? |
I run a 2276 (Web 86C, 48's) street car (weekender like you) with an aluminium case and 10.2:1 CR - in the UK. It runs perfectly fine temp wise - used to get pretty warm for the first 500 miles or so until everything settled down but now runs around 225F with not too much fluctuation - even when you're on it. No external cooler either.
I run on Shell Optimax - or whatever its called - 100 octane stuff and its fine on it. |
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UK Luke 72
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Joined: September 07, 2011
Posts: 2867
Location: Little Britain
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richierich
Samba Member
Joined: December 23, 2004
Posts: 889
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| Posted: Sat Jan 13, 2018 12:21 pm Post subject: Re: 2276 CR |
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| UK Luke 72 wrote: |
Ill be doing very similar Rich but with an 86b and EFI 
10.2:1 |
hey Luke, you decided to go with the 86B in the end then? What heads you running? |
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57BLITZ
Samba Member
Joined: June 12, 2012
Posts: 2385
Location: DEEK - U.S.A.
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| Posted: Sat Jan 13, 2018 12:49 pm Post subject: Re: 2276 CR |
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| jfats808 wrote: |
| Sounds like you ordered the heads without setting up the dh to see what you needed prior. Send the heads and get them cut to the target cc's you need. Chalk it up as a learning lesson. |
Sorry Dean . . . Yer gonna have to pay up to have it RIGHT! 
For everyone else . . . learn from this (or simply a reminder) . . . save money and time . . . check D/H BEFORE ordering heads!
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Jesucristo es mi Señor y Salvador! |
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UK Luke 72
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Location: Little Britain
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ac509
Samba Member
Joined: September 20, 2012
Posts: 160
Location: moved
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| Posted: Sat Jan 13, 2018 7:40 pm Post subject: Re: 2276 CR |
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lose does not equal loose
a screw can be loose and you can lose it. these are critical to knowing what we are talking about.
loose, it's not tight.
to lose something means it is lost.
i lost it. lose is lost. both are 4 letters. loose is opposite of tight. neither are 4 letters.
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