L28 Bigger Valves?

[TheCrazySwede]

Dear Forums,

 

I'm currently rebuilding a stock L28. I was looking at the DSI Big Valves ($408) but was questioning myself whether or not it's worth it. http://datsunspirit.com/?wpsc-product=dsi-big-valves

 

The Intake is 1mm larger, and the exhaust is 1.5mm larger. Looking at my own head, I noticed that the stock valves are already pretty large, and was wondering if bigger valves are worth the extra dough and if they are safe. Also, on that website, it states that the valves are longer. What would I have to change to accommodate for the extra bit of length? I'm planning on running a higher lift cam, but it's still a mild cam and not some crazy .560 racing cam.

 

What are your thoughts on this?

 

Cheers!

[roger280zx]

Well there is a benefit to larger valves given at some point.  What I don't get is what makes these valves worth $34 each ($408/12) while other stainless steel valves on the market are $16 each.  Am I missing something?  Even the Kameari long distance race stuff is $385.  The smaller L24 valves in my friends stroker where good enough to make 217rwhp. 

[TheCrazySwede]

I don't understand the justification of the price, either. Things that I'm planning on my rebuild are mostly Cam (Including rockers, retainers, springs), new pistons and proper balancing (within 0.5 grams) The stock valves look big enough for any performance need. So basically, I should be good with the stock sized valves, right? Unless anyone knows an affordable upgrade to the stock valves. I already know of SI Valves, but not entirely sure why they are considered an improvement over the stock valves. Are they just lighter? How much so?

[rturbo 930]

More info on those valves: http://datsunspirit.com/?p=1494

 

I'm not sure what your goals are, but it sounds like you're not doing anything crazy, so you probably have no use for those valves. You'd probably benefit more from a good port/polish.

Edited April 18, 2014 by rturbo 930

[Xnke]

Si valve makes the Nissan Competition valves...they are stainless, swirl polished, and oversize.

 

Altogether unneeded unless you are getting the head ported, and there isn't room to idealize the intake valve anyway.

[JMortensen]

I second the port and polish suggestion. Or cc the chambers and unshroud the valves. There's lots you can do before you get to the point where installing bigger valves is the best ROI.

[TheCrazySwede]

Gotcha, thanks guys for the advice. Much appreciated!

 

Looking into my build, I don't see it necessary to have bigger valves. The L28, thankfully, already has large valves, so I should be set. 

 

I wanted to make a post asking questions regarding an NA L28 build, but I know there a lot of them out there, although many of them have different circumstances and don't all have the answers I seek. I just don't want to be the guy who gets flamed with "Did you use the search engine??!!" haha.

 

I'm hoping to hit 200HP+ at the crank (Not to the wheels. Although that would be nice, too!) 

Do you guys know any good posts out there? I've found a couple, but most of them are discussions and not posts that actually follow a blueprint. 

 

Thanks guys, cheers!

[JMortensen]

zredbaron's post on his build to 275 whp might be useful. Would help if you described your plan a bit more. Induction, exhaust, etc. 200 bhp is not a hard target to hit.