G Atsma

Only in the past year or so have I heard about shimming to .050 before CB. Does that stabilize spring harmonics or is it something simpler than that?

tech@WS6store

iTrader: (2)

It does yes. it also allows you to build more pressure for better valve control as well as tear up your 2 piece seat/seals when you forget to put the shim on first.

G Atsma

Makes total sense! And I thought I was the only one who forgot stuff....... lol

omc8

iTrader: (7)

This ^ could be a good fit ,or ws6 store High lift hot cam same duration just more lift . or Howards Cams 222/225 .561/.578 lsa 112 or Tick Stage 3 turbo cam 5.3 223/227 .621/600 114+3

tech@WS6store

iTrader: (2)

Our high lift hot cam is catching on and quite a few are mixing and matching with springs they want which doesnt bother us!
We are actually going to run a sale on them soon again so if money is the issue...then next week is the answer.

pantera_efi

iTrader: (1)

Hi ALL, I should add 115 Seat is not a good choice for a Turbo Charged EX (EMAP Value ???) Valve Spring.
The Joe Nova "tech" is a report I too agree with, the EAP error %.
I find the RPM points are often OFF by 500.

The other items such as PV/Valve Float/C.R./Piston Speed are correct with NO ERROR.

Thus, thanks Joe for your report as a user of EAP OR EAP Pro ?

Lance

customblackbird

iTrader: (2)

Please explain why 115lb seat is a bad choice for the exhaust? I'm currently running that on my turbo 5.3 and have no issues to 11psi at 6500rpms.

JoeNova

115 lbs is considered low seat pressure for a turbo application and makes some worry about valve float.
Its still more seat pressure than LS6 springs (90 lbs), and has a much higher pressure rate when compared to PAC1218s (412 lbs/in vs 313 lbs/in) resulting in better overall valve control.

Lance's point is that none of those 3 springs is typically recommended for turbocharged engines due to either low seat pressure or low spring rate.
But when they work, they work.

customblackbird

iTrader: (2)

Gotcha! thanks for explaining it. What is a typical recommended turbo spring then? Something thats compatable with OE style lifters and isn't a dual spring setup thats hard on just about everything. I've also run the LS6 springs on stock 5.3 cam/engine that was centri supercharged to 5500-6k with no valve float. (Soft lobes, low lift helps) I liked it so much I got another set of LS6 springs for my spare 5.3 which has an LQ9 Johnson stock replacement hylift lifters and moly pushrods and bushed rockers on stock 5.3 706 heads. That engine will be turbo'd as well.

JoeNova

The recommended PSI 1511ML springs have 130 lbs seat pressure. They have less spring rate than the Howard's springs though, so take it as you want.

Seat pressure is more important with heavy valves and turbo backpressure.

pantera_efi

iTrader: (1)

Hi CBB, sure a fair request, thanks.
Let us state a MAP of 15.lbs with common EMAP of 30.lbs (single turbo NOT twins)
Let us state a Exhaust Valve diameter of 1.6 = .8 radius x .8 = .6 x 3.14 = 1.884 x 30psi = 56 .lbs of seat pressure reduction.

NOW ADD the Oil Pressure of the HYD (??) lifter using the same math with further reduction observed divider by rocker ratio.

The same math is on the intake 2" valve seat pressure, 1 x 3.14 x 15 = 46 .lbs reduction + Hyd Lifter's Oil Pressure.

BOTTOM LINE is to measure your EMAP ?

NOW ALL should UNDERSTAND Spring Weight, the MOVING SIDE IS VALVE WEIGHT. (retainer/keepers AND 1/2 spring weight measured)

THUS ANOTHER reason to use the PSI 1511ML. (conical)

Lance

tech@WS6store

iTrader: (2)

Maybe im missing where this math is coming from. if the boost is pushing DOWN on the valve, then it would only be lost theoretically as the valve is coming UP....and you also forgot to subtract the stem circumference/area.
But your math deals with a flat surface, and the back of a valve is not...so calculate that correctly first then maybe the math will pan out...but still a reach.

8.Lug

That's complete and utter nonsense. You don't start looking at big cams for more flow only to restrict the flow in your heads.

pantera_efi

iTrader: (1)

Hi WS6, I am extremely concerned WHY you report my Maths are incorrect AND the fact that your report purpose is ONLY TO SPLIT A HAIR !

ALLOW me to EXPLAIN to ALL about the instant pressures inside a cylinder during a cycle.
When the piston is at TDC OVERLAP it moves away from the cylinder head "PULLING" the Valves Open due to LOW pressure in the cylinder, lower than the pressure in BOTH ports. (IN + EX Ports)
This pressure timing (piston/valve) is at worst possible time as the EX Valve is just seating AND the possible delay could, often does, allow Exhaust Gasses (hot gasses) to enter the cylinder when EX Valve seat pressure is to low. (seat bounce)

MY first Empirical observation was in 1994 for the AURA Camless Ranger Ford 2300 Twin Plug on my bench dyno.
A Kistler sensor was placed in one of the sparkplug holes, the valves were electromagnetic in operation controlled with MY ECU.

THUS as easy data log of instant cylinder pressure vs piston position.

ONE AURA requested test, from Borg Warner, was to create a cycle with Internal EGR, opening the EX Valve during the Intake Phase.

This worked fine when my ECU was used, commanding the EX Valve to open at the requested time in the cycle.

The BW engineers were VERY pleased to witness their theory proven (Internal EGR) in engine operation, a FIRST on this planet.

MY GUESS is that LS-1 Tech members DO NOT like mixing Exhaust Gases with Intake Gases in their engines.

Lance.

tech@WS6store

iTrader: (2)

First off your math operates on a flat plane which a valve is not, plus you forgot to subtract the valve stem area from your total area calculations. There are at least 2 issues with your math.

JoeNova

If the heads aren't a restriction in the first place, then its irrelevant.
Put 317s on a 5.3 and watch both power and torque completely tank vs the stock 862/706 heads.
Why do you think people mill the 243/799 heads .030 when swapping them onto their 5.3? Because the compression loss outweighs the flow gains.

Its not like it hasn't been tested. 5 minutes with google can save you embarassment.

http://www.superchevy.com/how-to/eng...der-head-test/

pantera_efi

iTrader: (1)

Hi ALL, let us believe in the WS6 report of area reduction caused by the Valve Stem = OK
THUS that area reduction would cause a CHANGE of LESS THAN ONE Pound (.74) of seat pressure with a measured EMAP of thirty (30) PSI.

The fair is fair about reports posted on LS-1 tech is observed.

The BEST item is the general agreement with respect to Valve Seat Pressure Requirement for a Turbo Engine.

Lance

8.Lug

G Atsma

5.3L = 323 cu. in. Pretty close.....

JoeNova

My L33 has 4 digit power. I think I know more about them than you do. Besides, nothing was EVER said about whether or not they had flat tops. The point is irrelevant anyway. An L33 with 862 heads will have 10.5:1 compression and make more power/torque than it did with the 799/243 heads. Just over half a point increase.
If you look at the dyno graph I just showed you, it was on a 470 HP 5.3. I'm sure if the 706 heads on that combo were a restriction at even 470 HP, it would have gained power with the 799s. It didn't.

243s too big for a stock 5.7? No, the 243s have smaller chambers than stock LS1 heads, so you get a compression bump from them. Flow aside, they gain power.

With heads, you have to balance compression and flow. You're not going to pick up horsepower with a 500 CFM head if it drops your compression to 6:1. Unfortunately, even the 706/862 heads flow enough for a 5.3, and a 243/799 on the same combo generally results in power loss.

If you want to come try it out for yourself, I have an engine dyno and some 5.3s ready. You're more than welcome to try and prove me wrong.