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Standard Valve Springs And Rev Limit

JustinP

By JustinP,
in Engines & Forced Induction

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JustinP Mentor

JustinP

Posted
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I am just wondering - what would be the highest rev limit before valve float might become an issue for me with standard valve springs?

The engine is an RB25DET Neo (solid lifters) with Tomei Type B cams (260deg and 9.15mm lift on IN/EX).

The bottom end has lighter forged pistons / rods and is fully balanced, I am wondering what it will rev to when it is all put together :)

Cheers

Justin

GTSBoy Grand Master

GTSBoy

Posted
Posted

Yuh, this is the catch 22 when you put bigger cams in. The cams make you able/want to use more revs from the point of view of breathing, but bigger lifts and longer durations = more aggressive ramp rates and makes it possible to float the valves at lower revs. It would be sensible to derate what you think you can get away with on stock cams in a Neo by at least 500rpm if you can't get solid advice from anyone.

JustinP Mentor

JustinP

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Thanks for the feedback everyone. If it is only going to cost me $300 for the Supertech springs I think I might as well get them too. I have come this far... why not!!!

One question regarding the Supertech springs - I notice they do not have any springs listed in their catalog specifically for RB25DET Neo. The have 2 versions of RB25DET springs, one for hydralic lifters (R33) and one for heads with a solid lifter CONVERSION.

I presume the second option will be OK with a Neo head, considering it comes with solid lifters as standard?

Thanks :)

For $300 I would through a set of supertech springs in, peace of mind, rather than getting it all together and find the standard springs have gone soft

JustinP Mentor

JustinP

Posted
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In any case, I can't seem to find any sets of supertechs for around $300!

I found these cheap ones though- miscellaneous brand!

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=160489842337#ht_500wt_725

cheap though, i wonder if they are any good.

they also sell with retainers:

http://www.ebay.com.au/itm/Nissan-RB25-Neo-Valve-Springs-Retainer-kit-/160477165278?pt=Motors_Car_Truck_Parts_Accessories&hash=item255d2f36de#ht_500wt_725

very well priced, but i wonder if they are any good.

:)

hmmm not sure, I would call supertech and ask, if not there are a few other brands of springs around that money as well.

JustinP Mentor

JustinP

Posted
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Posted

Makes sense!!!

Maybe I will give them a go - cheers :)

Performance Springs is the brand believe it or not,

They are an Aussie mob, and supposedly pretty good, but I have never used them myself

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