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RB30 stroker?

RB32DETT VL

By RB32DETT VL,
in Engines & Forced Induction

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RB32DETT VL Explorer

RB32DETT VL

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I ask because I currently have a 9.0:1 3L VL, with max power at 5200rpm and am looking forward to 7000rpm when I install the rb25 head, etc. I'm just concerned about how much boost I will eventually want to run, and the lag I'll experience with the low CR. The extra revs will mean I could stroke the engine and still increase the redline. I was originally looking at building a high CR N/A engine but the expense has led me to aim at forced induction from the start :)

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RB32DETT VL Explorer

RB32DETT VL

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Sorry, I realise this, but I have always planned on throwing the twin cam head on my engine, therefore installing new cams into my current engine would be a waste of money. When I build the engine I will rebuild the block as well as the head, which means when the head goes on, the higher possible revs will be acheved at the same time. I am talking more about piston speed when I ask about stroking the engine. I'm not so much worried about the cams or engine rpm at this stage.

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RB32DETT VL Explorer

RB32DETT VL

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Sorry Roy, I didn't put that very clearly. The redline of my engine after it's built will be much higher than it currently is, by roughly 2000rpm. This means that when I build the engine, if it was stroked at the same time, it is possible that I could still increase the rev limit over the current 5000 odd. If the engine was stroked, it is possible that it won't rev to 7000ish very happily, but it will still rev higher than it does now. Does that clear it up?

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Sydneykid Grand Master

Sydneykid

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A bit of RB30 data to start with...

Bore = 86 mm

Stroke = 85 mm

Rod length = 152.5 mm

Rod stroke ratio = 1.793

In order to get to 3,208 cc's you would need 92 mm stroke with 86 mm bore. That's 3mm shorter rods so the rod stroke ratio would be 1.625. Because of the increased angles, the shorter conrods have to be stronger to handle the side loadings. This means extra weight and more stress on the piston skirts and bores.

You have to buy a custom crank (~$4K) and a set of custom conrods (~$3K), plus a set of forged pistons ($2K).

My suggestion (and what we do) is to go for a larger bore, 87.5 mm with the standard stroke. This gives you 3,068 cc's for around half the cost. We rev them to 8,500 rpm with 900 bhp capability. That's good horsepower per dollar. :D

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RB32DETT VL Explorer

RB32DETT VL

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Thanks for the info SK. The piston speeds must be huge in RB30s doing 8.5 grand?? I couldn't be bothered working it out.

Basically, what I want to achieve is a really strong, flexible street setup, with the option of drag racing and maybe some track work.

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