ssanto

Hi,

Building up a LS3 415 road race motor. Going with either stock LS3 ported heads or a set of TSP "Brawler" heads (with hollow intake valves) that are pretty much the same as a ported LS3 head.

I found a new set of 823's ported by West Coast Racing setup with BTR Platinum 660 springs, titanium retainers, and BTR shaft rockers. The price is right. They flow the same as the Brawler head.

The problem - they are built with solid intake valves (not the hollow stem LS3 valve).

I plan using, Johnson 2110R lifters and a cam with up to 650 lift. Rev limiter will usually be set at 6800 but I may need to bump that up to 7k depending on the track and my gearing.

What's the limit for solid stainless steel intake valves? I know that hollow stem valves lets you carry the revs longer... but I don't yet have a sense of where that is and if 7k with solid lifters is just fine.

Thanks!

ssanto

Or to put it another way... what's the upper limit for RPM on a solid LS3 intake valve?

... using PAC double springs with 155 seat pressure and 400 open, titanium retainers, Johnson 2110R lifters and a Stage 4 cam w/ 240 duration at 0.050 and 0.650 lift

Thanks!

low2001gmc

iTrader: (148)

Depends on intake if like a stock LS3 or high ram. If you really prefer hollow stems, you may just want to get the Brawlers, or else if you're like me, you'll wish you had hollow stems, and will sooner or later end up getting. Go with what you really want.

ssanto

running an edelbrock super victor single plane and 4150 carb

low2001gmc

iTrader: (148)

2-300 RPM difference I would say. For N/A I prefer hollow stems for RPM. For Boosted or Lots of NOS, I recommend the Stainless Steel Valves for Strength.

ssanto

Right.. that's what I keep hearing 2-300 or 4-500 RPM difference. So the solid stainless valves go unstable at XYZ RPM. And the hollow let's me pull to XYZ+300 RPM. Is there any guidance or experience with solid valves that would help me know where about the XYZ is that they go unstable? Like if we're talking solid valves are rock solid up to 7500 and the hollow ones let me pull beyond that, then I'm good with solid. But if the solid ones start breaking up at 6500, then I'd need the hollow.

ssanto

I found an interesting data point...

https://www.airflowresearch.com/260c...nder-head/p582

The AFR LS3 260cc Mongoose head uses a 125 gram solid intake valve
And the specs say this - PAC Racing Spring 1.270" OD Hydraulic Roller Dual Valve Spring, 155 lbs. on seat, .650 maximum lift, Max RPM 7000-7200

So that's a good data point for a pretty reputable head manufacturer spec'ing a MAX RPM range for a setup using solid valves.

low2001gmc

iTrader: (148)

GPI in their Track Attack use Hollow Stems and in their Ported Heads recommend Hollow Stems, and them guys like to to rev to 7500+ with High Ram Manifolds. So there's that.

ssanto

Thanks! I'm gonna stick to getting hollow stems. I'll sleep better knowing I've got plenty of RPM headroom. This motor is intended to be powerful (hence the 415 cubes) but not trying to push the limit on anything so that it stays reliable. Hope to get 30-40 hours of track time between rebuilds which is what they get out of motors in TA2 road race series.

low2001gmc

iTrader: (148)

Alot of people run duals, but I prefer PSI ML1516 Single Springs with Titanium Retainers, same springs used on COPO Camaro and Endurance Races. Love them. Figure if they can withstand High RPM for extended periods of time, they must be good. And I limit my LS3 12-1 Truck to 7300 with 238-252, 113+4 Cam and Fast High Ram.

grinder11

iTrader: (1)

PAC duals here, but on a larger valved LS7. I used Ferrea hollow stem stainless intake valves. 30,000 miles and no issues. Shifts at 7,000. Just my opinion, but PAC and PSI are both top notch valvesprings.....

01CamaroSSTx

iTrader: (3)

Just my .02 but the Ferrea LS3 hollow stems would be a good choice over GM hollow stems. They're about 19g heavier due to the the thicker walls whichs makes them stronger but I seriously doubt those valve springs will know a difference between a hollow stem and a solid at 7K.

Bob570

I bet you'll be fine at 7000. My Camaro's rev limiter was at 7000 with solid stainless valves in my PRC 225s. If I remember correctly, they were right around 109g, which I think is what the stock 821 head's valves weigh.

Edit: Oops, I meant 823 head, not 821. The 823 head is the one that came on all the rec port engines except the LS3, those had solid valves.

01CamaroSSTx

iTrader: (3)

The stock LS3 hollow stem comes in at around 89g. Here's the weight of the Ferrea LS3 intake and exhaust valves.