Na bottom end?

[GavinJohnson]

Has anyone ever used a rb20de long block for a turbo application? I can get one cheap and throw the oil squirters out of my block in it just curious if anyones done it or had any Input

[NismoS-tune]

I think the non turbo engines have higher compression which isn't as friendly with turbo. Kick in more cash and get a better engine. I could be wrong about the high comp on non turbo rb20.

[rak123]

i think i read that the N/A motor is 9:1 and the force induced is 8.5:1, but could this be sloved with a thicker headgasket on the N/A motor to drop compression to throw more boost in?

I think the non turbo engines have higher compression which isn't as friendly with turbo. Kick in more cash and get a better engine. I could be wrong about the high comp on non turbo rb20.

[GavinJohnson]

That's what I was thinking of doing. Can get it for 250 and it has 30 k on it.

[Velders]

I do remember seeing a GTRC member converting a GTS to turbo. The higher compression could be nice, I'm worried that I'll regret staying with the stock 8.5:1 on my GT-R. I do see two problems thought, the RB20DE might not have rods or pistons that are as strong as the DET pieces. If the compression ratio of the DE was only 9:1 it wouldn't be to bad but its not, the compression ratio is actually 10.2:1. The Gibson Group A GT-R ran 9.5:1 but that was with better internals and race gas. I would be doubtful that a DE would be capable of reliably making any meaningful power.

[Skym]

There are heaps of RB20DE+T, RB25DE+T conversions downunder. The only problems is you need a good ECU tune (very important), low boost level (pistons are higher compression pistons), I think slightly thicker headgasket (stock RB20DET is 1.2mm and not 100 sure, but I think they use 1.0mm headgasket for RB20DE). The RB20DE, RB20DET shortblocks are identical, except higher compression pistons, no oil squirters for underside of pistons on RB20DE shortblock. Even the oil return, etc is there on the RB20DE shortblocks, but blocked off. Higher compression helps with offboost performance but limits the boost level you can run. Lower compression is the opposite where you can run more boost but lose offboost performance.

RB25DET is similar with higher compression pistons, as it can't take higher boost levels like RB20, RB26 can. Headgasket plays a role in the higher compression.

I would go with a RB20DET bottomend and refresh it and strengthen the known weak points with crank collar, ACL rings (I think these work with stock size, 0.5mm oversize pistons), ARP rod bolts, coated (reduces cavitation or burning of surface of bearings under hard use) ACL bearings. RB20DET bottomend is strong, so can take the abuse as long as you keep the stock rev limits and peak hp at lower rpm, say 6000rpm (reduces inertial load on bottomend that snaps conrods and puts hole in side of block, breaks conrod bolts, etc). Use a higher boost level to make up for lack of rpm.

Stock RB20DET pistons, conrods can handle 560hp, roughly 35psi of boost from a TO4Z turbo -

http://www.gtroc.com.au/forums/index.php?showtopic=298289

Also that's using a Nistune modified stock ECU.

In theory stock bottomend can handle 600hp at engine (100hp per piston is the safe hp limit of cast pistons, but can be pushed further for short burst's). But like GTR bottomend, stock RB20DET bottomend should be more reliable below 500hp at engine.

[MikeRWK]

are we in the stone age? rasing comp to 9-9.5 aint gonna hurt anything as long as you have a good tuner im going with either when i start building an engine for my car

[Bluerb240]

Meth injection kit will keep it cool if you go for big boost with a upgraded turbo.

[Skym]

On RB racecar engines they lower compression. RB20DET ran lower compression than factory compression and was running a higher boost level all of the time. But engine didn't last long, only 3000km between rebuilds (was quite reliable for a racecar engine, as V8's of that time lasted same km between rebuilds). Even a V8 guy I know who owned a RB20DET lowered the compression when using stock RB20DET bottomend and 400hp at engine with higher boost level. The cylinder size is small on RB20DET shortblock.

[t-bag]

Well definetly using a N/A head is a great idea.
Since its N/A, the intake ports and exhaust porks are slightly bigger. The valves should be the same size. Junk the cams for they have too much overlap and after 8psi, upping the boost will do nothing.
I think the head has potential, the block is junk.

[Bluerb240]

.....................

Anyone measure the DE ports vs the DET?

[t-bag]

instead of doing that, just check the casting numbers, much quicker than cc'ing a port.