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engine size choices


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Guest drift_me_silly

after the collaboration on "which head" and "dammit which turbo" i searched the options of "big" RB20's...and came up with a different result than i was expecting. revs equals wear, anyway you look at it. a square engine WILL deliver the goods down low, but have probable bearing problems when revvved out. shame. I think the best compromise comes in the form of the Trust 2.7 kit for the '26. while being 'longer' than the stock engine, i'm pretty sure this combo is the best option. smooth, tractable..and able to spin a relatively larger turbo on sooner...maybe just a little sooner, but that's all you need. with a redline of 9200rpm, CR 9.2:1 and an HKS 3037S, i reckon i've got two good engines in one. It all depends on the exhaust manifold now, internal size, length...getting economy up to 3k on the highway AND having response from the turbo after that will be easier than i'm guessing, now i've upped the ante with an RB26...i'm still two minds about it though...a revvy, light flywheel-equipped 2200cc revving out...magic to the ears...everyone's heard what i'm suggesting, and it's nothing new...but i believe it is a better compromise for the money involved.

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Hi drift_me_silly, you lost me, help me catch up..........

You believe a 2,200 cc RB engine revving to 9,200 rpm will have less wear than an 3,100 cc RB engine revving to 6,500 rpm and making the same power.

At 2,200 cc's the RB engine will have the standard RB20 stroke of 69.7 mm. At 9,200 rpm that's around 10.7 metres per second. At 3,100 cc's the RB engine will have the standard RB30 stroke of 85 mm. At 6,500 rpm that's around 9.2 metres per second. So the 2,200 cc engine is going to have around 16% more bore, piston and ring wear.

At 9,200 rpm (compared to 6,500 rpm) the 2,200 cc engine will have 42% accelerated wear on the camshafts, big end bearings, main bearings, cam belt, oil pump, water pump, alternator, power steering pump etc etc

Or have I missed something..............

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