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Title: Head upgrade from O44 to Superflow Post by: AlexB on September 02, 2019, 22:19:17 pm Currently in the process of upgrading the engine from my drag car ( The Jagerbug)
I’m changing the 2276 (82x94) engine from Cb 044 heads to some secondhand superflo heads I picked up a while back The Superflos have been flycut somewhat so have a chamber volume of 30cc which is pretty small, I want a final cr of about 12:1 Current deck height is 0.90 mm My calculations so far take me to using a 1.5mm copper head gasket (gives another 11cc according to my maths) which gives a top end volume of 41cc Using a 0.5mm cylinder spacer drops the deck to 1.4mm According to the Jmr calculator this gives a CR of 12.2 Does this sound correct ? Engine runs FK89 , 48 Ida’s and is not street driven - just want to up the breathing with the bigger valve better flowing heads Cheers Alex Title: Re: Head upgrade from O44 to Superflow Post by: richie on September 03, 2019, 02:17:55 am I make that 12.4/1
Forget all the calcs for 1.5mm copper to cc, its just deck height in real world so deck height is 0.9+1.5+0.5mm= 2.9mm[ which to me is way to much for a N/A race engine] head cc 30 with 94x 82 on jmr calc shows 12.4/1 cheers Richie Title: Re: Head upgrade from O44 to Superflow Post by: AlexB on September 03, 2019, 07:21:25 am I make that 12.4/1 Forget all the calcs for 1.5mm copper to cc, its just deck height in real world so deck height is 0.9+1.5+0.5mm= 2.9mm[ which to me is way to much for a N/A race engine] head cc 30 with 94x 82 on jmr calc shows 12.4/1 cheers Richie So with a deck of 1.4 and 30cc chamber I get a comp ratio of 15.3 /1 To drop that further would I be better off machining pockets /dishing the pistons ? Cheers Alex Title: Re: Head upgrade from O44 to Superflow Post by: Erlend / bug66 on September 03, 2019, 08:08:02 am If the superflos has been running a lot with 30cc chambers, they could be pretty tired.. Depending on the year of production, the aluminium is pretty "light"..
Hold a SF in one hand and a new competition eliminator in the other. The difference in mass is pretty obvious.. Title: Re: Head upgrade from O44 to Superflow Post by: leec on September 03, 2019, 09:48:13 am Would you need valve notches as well? Do you include the cc for them as well in CR calculation?
Title: Re: Head upgrade from O44 to Superflow Post by: AlexB on September 03, 2019, 10:08:12 am Hadn’t considered valve notch capacity - although thought they might be necessary, I suppose a decent pocket machined
In the piston crown would solve the need for valve notches and decrease CR Title: Re: Head upgrade from O44 to Superflow Post by: AlexB on September 12, 2019, 09:33:54 am Ok - so rather than increasing the deck, if I machine a 70mm dish 1.5mm deep in the piston crowns then it will gain 5.6cc into the combustion chamber, then keeping the deck at 1.4mm that gives 13.4 compression - sounds more reasonable ?
Title: Re: Head upgrade from O44 to Superflow Post by: DaveN on September 12, 2019, 18:03:28 pm If it was my engine, I would increase the deck height, notch the pistons accordingly and the compression ratio is what it is. It’s a race motor so you’re going to be running race fuel so high compression ratios won’t be a problem.
Title: Re: Head upgrade from O44 to Superflow Post by: Martin S. on September 14, 2019, 14:14:33 pm For mine it was unshrouding the valve. Then, dishing the pistons to match.
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