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Post by deefer66 on Sept 27, 2019 21:46:55 GMT
... nearly an answer!.. I think its confirming they're same as stock.. I've tried recording the question  |
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Post by Zed on Sept 28, 2019 5:22:12 GMT
Pretty hopeless answer! Probably as Westy says the birral cylinders are all the same and stock length. I might try a dummy question asking the length of the 104's just to see what they say.
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Post by 77westy on Sept 30, 2019 12:05:00 GMT
Does it really matter? If they’re too long you’ll need a bit machining off them, if they’re too short you’ll need to fit spacers. Either way you’ll need to measure what you have and do some sums.
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Post by deefer66 on Sept 30, 2019 12:14:13 GMT
Lost out in the auction for the birals anyway.. Got a set of overbored 94.5 with new KS pistons to consider a follow up on 😁
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Post by Zed on Sept 30, 2019 15:43:25 GMT
Does it really matter? If they’re too long you’ll need a bit machining off them, if they’re too short you’ll need to fit spacers. Either way you’ll need to measure what you have and do some sums. The only engine I built from scratch was done on the dining table. I didn't have to have anything machined. It would have royally pissed me off to find the barrels 3mm longer than expected having selected rods to make the crank, deck and CR work with a standard width engine. So it the greater scheme of things it doesn't "matter" but pre-warned I would have probably selected longer rods and suffered a wider engine rather than have to trust an unknown shop to shorten the barrels. Knowledge is power. Next time I think of something that might be helpful I'll keep it to myself. |
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Post by 77westy on Sept 30, 2019 17:35:54 GMT
Does it really matter? If they’re too long you’ll need a bit machining off them, if they’re too short you’ll need to fit spacers. Either way you’ll need to measure what you have and do some sums. Next time I think of something that might be helpful I'll keep it to myself. Sorry mate, I didn’t mean to piss you off. |
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Post by deefer66 on Nov 5, 2019 14:34:36 GMT
While waiting for head and cranks to come back from shop... assuming did it's usuall thing and made as ass... piston dishes on the 2ltr pots are 15cc not 10 like the last time so compression ratio likely to take a hit....
Are options call shop and ask for more skim off head face to reduce chamber... skim top of piston to reduce dish and ditch barrel spacers and run as tight a deck as poss, Or just live with mid 7's ish CR.
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Post by 77westy on Nov 9, 2019 19:56:55 GMT
I think you’ll be disappointed with engine performance if you have a SCR mid 7:1. Get the deck down to 1mm, but not less. No problem running without cylinder shims if you need to.
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Post by deefer66 on Nov 9, 2019 20:16:41 GMT
Getting 1.5mm skimmed off the heads to reduce the chambers by about 5cc I reckon.. with a deck height down at 1mm should push it back up.. will check when all the bits come back then re-evaluate cam / compression rafio with 1800 heads and 2ltr pistons situation. Might be new pistons only way to go ...
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Post by deefer66 on Nov 16, 2019 7:06:43 GMT
Managed 1mm off the heads before barrel touching was a worry, got chambers down to 48mm! Will need to aim for deck height about 1.28 with shims for a 9 DCR..8.32 CR.. subject to final checks / shim size jumps and then on to find how it performs
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Post by Zed on Nov 16, 2019 8:38:28 GMT
Wouldn't the DCR be less than static?
How are you calculating DCR?
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Post by deefer66 on Nov 16, 2019 9:17:35 GMT
Wouldn't the DCR be less than static? How are you calculating DCR? Yes.. shouldn't type that early.. other way round if I get deck to 1.28, CR 9, DCR 8.32. Each 0.11mm step in deck height changes CR by 0.1 DCR from an excel spreadsheet checked by a few different values with a CAD drawing for quality control 👍 |
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Post by Zed on Mar 4, 2020 12:46:20 GMT
I should be adding to this again this year. I have plans to hack 2mm off my barrels, dish the pistons and change the cam. But the reason for the cam change is purely to deal with the increased CR which I won't be able to get low enough for a stock cam.
Cheapy C25 or the split duration Webcam. There's a huge difference in price.
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Post by chad on Mar 7, 2020 15:29:08 GMT
So the boats finished so it's back to engine dabbling then?
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Post by Zed on Mar 8, 2020 8:06:23 GMT
So the boats finished so it's back to engine dabbling then? Boats are like campers, never finished.  |
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