rb20/25

[diehard_skyline]

I have a deal on a rb25de really cheap but now im looking if its possible to put a rb20det head on the rb25de bloc with the rb25 crank and rod whit the rb20 pistons on , or is it possible to drop the copression ratio from 10 to 1 to 9 to 1 whitout changing the pistons and put my turbo on the engine and make it a rb25det whit a litle bit less power ????

thank you in advance for your informations

[Skym]

The RB25DE has 86mm pistons and RB20DET has 78mm pistons. The heads match, so no RB20DET head won't bolt onto a short block fitted with 86mm pistons without modification. They fitted a RB20 head on a RB30E bottomend (NA engine, not turbo) in Japan, but required welding up the oil, water gallery's in RB20 head. I think it was a Tommy Kaira RB30DE (M30).

RB25DE NA head is used with NA RB30E bottomend to make a RB30 engine. RB25DE, RB20DET heads use the same sensors, so it saves rewiring car for new engine.

RB25DE head is also used on top of a RB25DET bottomend. But RB25DE head is designed for N/A application, so valve springs need to be upgraded to turbospec valve springs. Also NA RB25DE shortblock doesn't have oilsquirters, only turbo shortblocks like RB25DET have oilsquirters.

[diehard_skyline]

so I cant only put my manifold with my turbo and make it run whit a rb25det ecu .

[FITZY_07]

If you dont plan on building a Rb30, just buy a rb25 or rb20.. save some time and headache...

[PL_GTR]

so I cant only put my manifold with my turbo and make it run whit a rb25det ecu .

Not going to work dude, rb25de does not have any "turbo" ready parts, a lot of work to make an turbo version of this. Easily over 1000 dollars if your just looking at the $ issue.

[Skym]

You should be able to turbocharge a RB25DE engine, just like you can turbocharge a RB20DE engine, as the holes for oil return, oilfeed for turbo should be there, but blanked off on the RB25DE, RB20DE shortblocks. Alot of people have turbocharged a RB20DE (some use it for I guess a cheaper replacement), but you are limited to a lower boost level, due to higher compression.

That's why most fit a R33 RB25DET bottomend to modified NA RB25DE head, as RB25DET bottomend has everthing you need for a turbo. Some fit RB26 bottomend, due to lower compression pistons, stronger conrods, etc.

Stock RB20DET ECU can run the turbocharged RB25DE combo.

When you think about it, it's cheaper to start with a stock RB26 engine, as your trying to reproduce something that's already around. But RB30 has more torque, hp than RB26 and is a popular conversion into the R32 GTS, Laurel (old school Maxima), GTR chassis.

This R32 showcar has RB25DE head, RB30 bottomend with carbon RB26 camcovers -

http://www.youtube.com/watch?v=KKPGcZN5FoM

This is the Tommy Kaira RB30DE (M30) -

http://www.youtube.com/watch?v=uoQTBC71YrQ&feature=related

Sound of M30 engine -

http://www.youtube.com/watch?v=Bq3LKwUqN3Q

[diehard_skyline]

thank you for the informations guys