willyfastz

Deffenently, you always have to factor in boost when setting up the valvetrain on any boosted application.

redrckt97

I'd sure want dual springs with the 1.8 rockers - if only for the protection from a valve dropping in the cylinder if a spring breaks.
With the blower, you surely have plenty of hp.

Eric D

Interesting, what are these factors you speak of?

099blancoss

PAC's 1521 is a premium nitrided dual spring. Bout the best on the market IMO. Expensive ? Heck yes but to be honest I dont like trusting my engine to the cheapest springs I can find. PAC are one of the very best and I look at reputation and industry. We also have a mega spring package ( for .700 lift cams)from HKE that is made by PAC. The 1518 is a drop in replacement though and would be a good choice.

SaberD

even if he was running 20 psi think about it. there is little more than a square inch of area on the intake valve, thats only 20 lbs of force on the valve. that wouldnt even come close to pushing the valve off the seat even with stock springs. and on the downstroke, the pressure created from combustion is astronomically larger than the amount of pressure created by the blower. if its actually possible to to unseat the valve due to intake pressure, i must be missing something pretty serious.

willyfastz

I'm not going to get into a long drawn out deal about boost and valvetrain. Boost does effect your valvetrain in an adverse way. The added cylinder presses created can make life terrible for the valves and springs. I've seen bent valves and sagging springs (dual springs) from some boosted deals.

I would not use LS6 springs as they do a marginal job at best on a stock setup. If added to a setup like the OP's they would be taken well out of the relm of their designed usage. A set of PAC 1218 beehives would be a good spring for this setup. The 1518's would deff. the most spring I would use in this setup. Make sure to run a good set of pushrods as well.

lucky131969

Please do. I'm sure many would appreciate your insight...because, I have never seen it discussed on this forum before.

Eric D

So what unique features in your suggested PAC 1218 make it superior to the stock spring for supercharging? So using PAC 1218 would keep the valves from bending? I would really like to understand how this works.

TheRadioFlyer

I had a set of LS6 yellow springs available when i installed my rockers but my mechanic advised against them stating that he'd seen LS6 springs break, but never the LS1 springs. While the LS1 springs may not be as strong they're rather durable.

I plan to get a set of Pac 1218 springs for the swap-out.

I would think of the valve bending he's talking about is the result of a failed or weak spring hitting a forged piston.

WKMCD

I run the PAC 1521's and they show minimal difference from new with a .660 cam most of 12k miles.

willyfastz

Yeah, we've run those on quite a few high lift cams and the last ones I tested were within 2-3lbs of new. You wont see that from most of the other brands on the market.

willyfastz

Right, valve float will cause bent valves. There's a lot of people that have valve float or are near float that have no idea.

099blancoss

Thats why we like them PAC also makes a mega spring package for HKE for our .700 lift cams. The 1521 is overkill here, and a lot more money than the rest of the doubles but a superior spring that you can trust.

willyfastz

Pac has spings that will go more than .700 lift. We're doing a set on a .800 + lift deal now.

099blancoss

Nice !