Hydraulic To Solid Using Neo Parts

[Ganador]

Hi not sure on this one. I'm looking at doing a RB30 25 head. I have a NEO head and a S1/2 25 head. I want to put the S1/2 head on but was looking at making it solid lifters

Question is, am i able to use the parts out of the NEO head to convert the S1/2 head to solid?

Cheers, Dave.

[DVS JEZ]

Use the neo head?

[Akshunhiro]

Use the neo head!

[Ganador]

My question wasn't answered

If I use the NEO head on the stock 30 bottom the CR will be to high, correct? Reasons why I want to use the S1/2 head.

[Akshunhiro]

I don't believe so. When I was researching a 25/30, I read that the average was 8.2:1 which was considered too low.

Obviously depends what pistons you use but 8.5-9.1 was recommended.

Edited October 13, 2012 by Akshunhiro

[brad 110]

The buckets will not interchange from the neo (solid) head to the series 1/2 r33 hyd head , nor will the valves or springs or cam shafts . The neo head would raise the compression approx 1.25/1.5 compression points over the r33 head

Why convert it to solid on a three litre engine as you won't be able to spin the engine hard enough to worry the hydraulic lifter, fit some super tech or Tomei type a springs and ensure the inlet spring seat pressures don't exceed 78 pound or the VCt won't activate. Easierly possible to exceed 450 rwkw with hydraulics and pon 256 camshafts with supporting components using e85

The boys above have a point re the neo head is a far better animal if you are prepared to get rid of the std shim over bucket and make it shim under or shim less cheers brad

[Ganador]

Thanks Brad. Good point there about not being able to turn the engine hard enough. As I'm keeping the bottom stock, hydraulic head with mild cams and springs is the go then.

Thanks, got some good info there.

[Ganador]

Just to add. Would something like these http://www.camshaftshop.com/products.php?productid=1049#specs with 84lbs Supertech springs (couldnt see smaller ones) work well

[KiwiRS4T]

Use the Neo head. Better in every way - it will not have too high compression. I have stock pistons with Rb25 head and only 132psi per cylinder. Even with higher compression pistons the Neo head will not be too much.

[Ganador]

Use the Neo head. Better in every way - it will not have too high compression. I have stock pistons with Rb25 head and only 132psi per cylinder. Even with higher compression pistons the Neo head will not be too much.

any ref/info to back this?

[brad 110]

The seat pressure changes depending on how far the valve seat is cut into the insert, what valves are used, the collet and retainer and any spring seat under spring. Many spring testers will vary in readings by plus or minus 10 percent. I can only comment that if your running 80 psi of oil pressure ( as oil pressure is what drives the cam gear to advance camshaft so 110 psi oil pressure will overcome a higher spring rate than 80 psi) 80 psi seat and from memory 270 on the nose is about the limit, even then cam chader can be evident on advance activation. Bear in mind the restrictors used in block will change all these findings as they will vary the actual oil gallery pressure in the head. All these tests were done on a circuit based car using a 0.9 mm rear feed, blocked centre and std front feed, with a main oil gallery pressure of 80 psi.

[KiwiRS4T]

any ref/info to back this?

Which bit don't you believe? As per the RB30 pdf stock pistons with rb25 non neo head will result in about 8.2:1 and I have measured my compressions at around 132psi per cylinder which is in line with what others have got. The slightly smaller capacity of the Neo head will not raise the compression ratio very much - don't have the fugure to hand - maybe one of the people who have a neo head can report.

Here's one:

Rank: RB25DET

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• urtwhistle
  
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• 627 posts
  

#13

Posted 08 June 2012 - 02:28 PMHey theres nothing wrong with using a neo head I know I have.

I used ACL 8.5:1 pistons on my 1st motor and Mahle 8.5:1's on my second. On the second I decked the head and also decked the block to a 0 deck height. standard nissan rb25 head gasket & I also run BP98 with no problems. I don't think you will have any problems unless your trying to put 65 psi of boost into it. but hey thats just my experience so far.

[brad 110]

10.5 cc,s smaller than r33 head from memory .

51.5 compared to 62cc give or take a cc

[Ganador]

Which bit don't you believe? As per the RB30 pdf stock pistons with rb25 non neo head will result in about 8.2:1 and I have measured my compressions at around 132psi per cylinder which is in line with what others have got. The slightly smaller capacity of the Neo head will not raise the compression ratio very much - don't have the fugure to hand - maybe one of the people who have a neo head can report.

i believe you are measuring cylinder compression not compression ratio. 2 very different things.

[KiwiRS4T]

i believe you are measuring cylinder compression not compression ratio. 2 very different things.

??Yes of course they are two different measurements but directly related - a higher compression ratio will result in higher cylinder compressions ergo a low cylinder compression reading in a good motor (leak down test shows my motor is sound) is indicative of a low CR .

Have you actually read the RB30 pdf in the RB 30 section?

[KiwiRS4T]

??Yes of course they are two different measurements but directly related - a higher compression ratio will result in higher cylinder compressions ergo a low cylinder compression reading in a good motor (leak down test shows my motor is sound) is indicative of a low CR . My combination of stock pistons with an RB25DE head is very common and the figures of 8.2:1 and compressions in the low 130's have been repeated many times.

Have you actually read the RB30 pdf in the RB 30 section?