For The Engineers (hydraulic Lifter Design)

[Cubes]

I have pulled a set of lifters from an R32 RB25DE and R32 RB20DET motor.

Both lifters are differently designed.

The R32 RB25DE is prone to valve float and pump up as soon as it gets a little boost in to it (assumed due to the same valve spring controlling a larger heavier valve + boost holding the valves open)

2 out of 24 in the R32 RB25DE head have movement and causing a little valve train noise so I'm pulling them apart and cleaning them out.

I'm considering the rb20det lifters as the design seems to look a little better. Not sure why though lol

For those who are engineering minded which do you believe is the better designed?

They are both interchangeable as they measure up the same.

Pics attached.

[raZ1911]

What did you end up going with?

[rob82]

I have pulled a set of lifters from an R32 RB25DE and R32 RB20DET motor.

Both lifters are differently designed.

The R32 RB25DE is prone to valve float and pump up as soon as it gets a little boost in to it (assumed due to the same valve spring controlling a larger heavier valve + boost holding the valves open)

2 out of 24 in the R32 RB25DE head have movement and causing a little valve train noise so I'm pulling them apart and cleaning them out.

I'm considering the rb20det lifters as the design seems to look a little better. Not sure why though lol

For those who are engineering minded which do you believe is the better designed?

They are both interchangeable as they measure up the same.

Pics attached.

Do you drop a cylinder when the lifters float?

[Cubes]

It sure did. I suspect it was on the exhaust side as there was zero difference to vacuum. Possibly the tight std turbo scroll shooting exh. back pressure through the roof.

Noticeably one cylinder so possibly slightly off installed heights from factory or one extremely weak spring.

[RAZOR32]

I have a R32 RB25 de that has been fully rebuilt with forged pistons treated rods all ARP bolts Tomei cams (256) performance valve springs ect and it really doesn't wont to rev it drops a cylinder (sometimes) when you try to rev it at all past about 5500rpm the turbo is only a R34 Gtt high flow running about 19psi, sounds like I’m having the same trouble as you? I’ve checked everything else a number of times e.g. coil packs. My new set up I have is a Gt3076r with 0.82 rear, Turbosmart 50mm gate and 6boost manifold, I’m worried that when I put on this set up the problem will only get a lot worse, what can be done to get rid of the problem?? I’ve spent heaps on this motor and this is just really pissing me off.

Cheers

[Cubes]

Interesting.. Since I've dropped the valve springs in to mine and at the same time dropped the gt30 turbo on it flicks to its 7.3k rev limit without problems.

I've been warned not to push the .82 GT30 turbo much more than 310rwkw as I was told the back pressure on the exhaust side is too high that will result in slight float eventually causing it to drop a valve.

[rob82]

Interesting.. Since I've dropped the valve springs in to mine and at the same time dropped the gt30 turbo on it flicks to its 7.3k rev limit without problems.

I've been warned not to push the .82 GT30 turbo much more than 310rwkw as I was told the back pressure on the exhaust side is too high that will result in slight float eventually causing it to drop a valve.

Have never seen that hapen before. Why are you reving your RB30 bottom end to 7300rpm??? What cams and are they dialled in?

[T04GTR]

interesting! nice job getting them apart! i havent tried that yet...

but you should go with the most "modern" lifter. nissan would be superseding parts for better ones.

as there is the same part number for all nissan bucket hydrolic lifters. ie: ca,vg,rb. all the same and all interchangable.

just the newer ones have been improved. (lets hope its not a cheaper one the go for!!!)