y8s

iTrader: (8)

oh herro: $30 lash caps. Are these the ones you got from the weight lifter company? haha

http://cgi.ebay.com/ebaymotors/NEW-B...2em118Q2el1247

samnavy

iTrader: (7)

So, longer duration/lift allows more air through the head? I thought the limitation of the head was the actual layout of the air passages (small) and not the size/volume of the valves.

In the end, how much more RPM are we talking about here? The number for the stock valvetrain seems to be 7200 as an upper limit. To be worth anything, I'd think you'd want to see a 500-800rpm improvement. So, would converting to shim/bucket let you get up to the 8000rpm range... 8500?

I hesitate to think what the next limitation is. Turbo flow? Pump gears? Bottom end?

This mod isn't for me, but I'm still trying to figure out what the end-result in performance will be. Will it make more power? Will it rev quicker? If so, then how much... and where will you see the gains... and will the wear-and-tear on other components be worth it?

y8s

iTrader: (8)

That's my redline stock... I think people safely run 7500-7800 on the stock guts. Maybe that's later cars. minus the MSM.

the stress on the bottom end goes up exponentially with RPM so yes, that may very well be the limitation. I think with a full top to bottom motor build, running 8k isn't out of the question. Hell, I'll try it.

Lets see... all flow related items that need more flow with higher RPM become limiting factors: injectors, turbo, pumps can cavitate, harmonic damper, etc.

but the benefits are (if you keep your torque up) linear increase in hp as revs increase. Think S2000. Look at the power go up above 7000 rpm... yet torque is constant.

cjernigan

iTrader: (13)

Over 300 HP at 7.5 psi wowza. Wish we were so fortunate.

y8s

iTrader: (8)

couldn't be the .2 or .4 more litres...

m2cupcar

iTrader: (5)

I don't know the specs on the springs we used with our cams but they were noticeably less stiff just by squeezing. Ideally you want less spring rate for a lighter valve train since you're moving less mass. I'm paraphrasing the engine builder, but the spring rate needs to be stiff enough for a good return on the valve (quick action) with minimal force against the lobe at compression. That said, we weren't revving past 7500. Our cams were geared more for torque and not high rpm power. So rev limit would also play into spring rate to avoid float. My guess is that's the point behind upgrading the springs on the stock valve train - to keep those giant shims from shooting out.

Stealth97

iTrader: (5)

FYI I have a built engine with basically stock '99 valvetrain, and I occasionally spin it to 8k, I have great power at 7k but power really starts to drop off around 7200 or so, and by 8k my hp and tq are just about non-existent... I think its due to valve float.

Ben

iTrader: (33)

i think it's your cams

Stealth97

iTrader: (5)

could be either or both. Have not seen too many N/A 8krpm dyno pulls, but yeah, Jerry seems to think the stock cams are really holding me back... I agree.

patsmx5

iTrader: (16)

+1. the faster you spin the motor, the less time the valve is open and it needs to draw in the same amount of air. Cams are what's killing it most likely, I doubt it's floating valves.

Ben

iTrader: (33)

valve float will feel more like a misfire

Stealth97

iTrader: (5)

Got to be the cams then. I need to pimp my valvetrain.. someone buy my NX kit

y8s

iTrader: (8)

cam grind group buy!! heh.

y8s

iTrader: (8)

SO I found a couple things:

1. Manley makes 6mm lash caps that run for 30-45 for a whole set depending on where you get them (flatlander, summit, jegs).

2. the FM valve springs are the exact same rates listed on the supertech website. belfab has the set for roughly the same price.

3. Actually with a little looking around, Import Performance Parts/Flatlander has the valves and springs significantly cheaper than other places.

hmm.

neogenesis2004

iTrader: (12)

Those are indeed the ones

y8s

iTrader: (8)

kinda creepy, i'll probably go with flatlander and just get the whole valvetrain setup.

soflarick

iTrader: (8)

I'd like to find a place that can sell just the Ti retainers and locks.

neogenesis2004

iTrader: (12)

The retainers are made specifically for the springs. The super tech springs require their springs seats and retainers for out cars. My super tech springs were actually shorter than the stock springs. The winding wasn't as tight though, so they could still support more lift.

I would definitely get the entire valve train in a kit Matt. Those are the shims I am using though. I probably have 40hrs invested in grinding them myself with the knife sharpener though. I couldn't find a place locally that would grind them for me. Most places thought I was crazy to even ask.

y8s

iTrader: (8)

or i can just order the supertech pre-sized ones...$4ea is much less than I'd charge myself in labor.

neogenesis2004

iTrader: (12)

You'll have to order them very last so that you can measure needed clearances.