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As I dive into the motor, I want to make sure this thing is done right once and for all. As I've said in previous posts, it was professionally built. One thing that stands out is that the builder stated that the valve springs I said I wanted to use were not sufficient to hold over 10lbs of boost, which I didn't understand because I thought they were plenty. Here's the whole engine build for reference:
Engine: 355, fully forged, balanced and blueprinted by Tom Masek Custom Racing Engines
PTK Gen II LT1 system
Full stainless steel headers
Precision T76GTS turbo
A2A front-mount IC
Turbosmart 38mm BO valve
AFR 195cc LT4 heads with FI port work by Lloyd Elliot
Ported LT4 Intake by Lloyd Elliot (machined for monoblade)
AS&M monoblade throttle body
Lunati Sledgehammer crank
Lunati Pro Mod rods
JE Extreme Duty 23 Degree Inverted Dome Top Pistons (9.08:1 CR). Pistons thermally coated
Howard 4-bolt main billet caps
Pro-Gram rear main cap
Custom Ultradyne cam (CHS 290/290-14NR, 232/232 @ .050, .544lift w/1.6RR)
Morel lifters
Smith Bros custom pushrods
Comp Promag 1.6 Rockers
Comp 26120 beehive valve springs
REV Severe Duty stainless steel valves; 2.02" int/1.60" ex
MSD BTM ignition and coil
Canton fabbed-aluminum valve covers
Canton road race oil pan
Mammoth BeCool radiator
Custom tuned by Westech
Here are the specs on the valve springs according to Comp:
Now here is what the engine builder listed, then noted later:
He wrote at the top of the build sheet "10lbs boost max." From the combo I have, I think that the motor should easily be able to handle 15lbs of boost on pump gas. I thought these springs were well-above specs to handle that. How does it look to you guys?
Last edited by Snorkelface; 01-25-2018 at 02:06 PM.
If they're installed and paid for, I'd run them to see how much boost is possible before you see any limitations. The one thing that strikes me from their written description is that they utilize a lower spring rate to achieve the "lighter" feel in the valvetrain. If you find that they're unsuited for your combo and boost levels, they're easily swapped out later. Boost leaks aren't risky enough to throw $200+ at a problem that may or may not exist, IMO.
FWIW, stock LS6 springs have been proven for 13+ lbs of boost. I remember reading somewhere that those springs are 294lbs at open vs your spring's 377lbs, but I'm getting a range of seat pressure results for LS6 springs in my searches. Generally 90-100lbs which is still lower than the ones in comparison.
If they're installed and paid for, I'd run them to see how much boost is possible before you see any limitations. The one thing that strikes me from their written description is that they utilize a lower spring rate to achieve the "lighter" feel in the valvetrain. If you find that they're unsuited for your combo and boost levels, they're easily swapped out later. Boost leaks aren't risky enough to throw $200+ at a problem that may or may not exist, IMO.
FWIW, stock LS6 springs have been proven for 13+ lbs of boost.
I'm pulling the motor, so I'd rather just put whatever would work best in now rather than risk it. Yeah, they appealed to me as I wanted to spin this thing over 6k with road racing.
Contact LE about your boost intentions since he did the heads. I would take his advice on springs. Maybe the Comp bee hives will be OK...Although a dual spring would give more insurance if you break a single bee hive spring
That was something I read recently as well and very much makes sense. If the springs test well when I take them off, I'll sell'em for a few bucks and feel better about the assurance of a dual spring.
Good idea, I'll reach out to him. Thanks!
Originally Posted by ******
Contact LE about your boost intentions since he did the heads. I would take his advice on springs. Maybe the Comp bee hives will be OK...Although a dual spring would give more insurance if you break a single bee hive spring
Contact LE about your boost intentions since he did the heads. I would take his advice on springs. Maybe the Comp bee hives will be OK...Although a dual spring would give more insurance if you break a single bee hive spring
I would call AFR and get the springs that they sell with those heads.
I have the springs that came with the heads in a box. I really don't know the specs on them, but they are double springs. �� EDIT: I just looked them up, and the advertised pressures are less than my current spring's advertised specs, and right inline with the as-tested pressures. I think I need more for 15lbs+. But they're nice, I should probably sell them. Haha These aren't the ones that come with the heads standard, they got some optional springs. Looks like the person I bought the heads from had a flat tappet setup. The standard ones would have been nice.
Originally Posted by KW Baraka
I would call AFR and get the springs that they sell with those heads.
But that's just me.
KW
Last edited by Snorkelface; 11-01-2017 at 01:55 AM.
The one thing that strikes me from their written description is that they utilize a lower spring rate to achieve the "lighter" feel in the valvetrain.
From what I understand about these springs isn't that they're light in rate, they're light in weight and they can be because multi-coil heavy-rate springs are mostly that way simply to prevent their own harmonics from affecting their ability to control the valve. Progressively-wound springs don't have this issue - or at least it's not as much of an issue.
From what I understand about these springs isn't that they're light in rate, they're light in weight and they can be because multi-coil heavy-rate springs are mostly that way simply to prevent their own harmonics from affecting their ability to control the valve. Progressively-wound springs don't have this issue - or at least it's not as much of an issue.
"This is achieved with less spring pressure" was the indicator in the OP's picture. But yes, they're also lighter in weight.
Manley Nextek springs here. The original springs (patriot gold extreme) didn't like the 15+ lbs of boost with how they were set up and caused some light float up top. Make sure the rest of your valvetrain is ready for the extra spring pressure.
Hi Snorkel, NO ONE got this requirement correct, the Seat Pressure.
My method is Simple Math, with the Exhaust Manifold Absolute Pressure as MOST important, then the Manifold Absolute Pressure ( Intake Boost Pressure)
The reason is that it is COMMON to have 2X the pressure in the Exhaust Manifold with a turbo (not stated) OR just the intake pressure with a SC.
The Valve area of a 2" intake is the simple P*I X Radius Squared or 3.14 x 1 the area.
Now the Boost of 15 .lbs x 3.14 = 45 .lbs of air pressure "pushing" the valve open OR a reduction of SEAT PRESSURE of 45 .lbs.
The builder/head manufacturer new this about the Intake Side.
The Exhaust Side was forgotten !
The same math of a EX 1.6" = .64 x 3.14 x EMAP of ??? could be 60 .lbs of seat pressure reduction.
Hi Snorkel, NO ONE got this requirement correct, the Seat Pressure.
My method is Simple Math, with the Exhaust Manifold Absolute Pressure as MOST important, then the Manifold Absolute Pressure ( Intake Boost Pressure)
The reason is that it is COMMON to have 2X the pressure in the Exhaust Manifold with a turbo (not stated) OR just the intake pressure with a SC.
The Valve area of a 2" intake is the simple P*I X Radius Squared or 3.14 x 1 the area.
Now the Boost of 15 .lbs x 3.14 = 45 .lbs of air pressure "pushing" the valve open OR a reduction of SEAT PRESSURE of 45 .lbs.
The builder/head manufacturer new this about the Intake Side.
The Exhaust Side was forgotten !
The same math of a EX 1.6" = .64 x 3.14 x EMAP of ??? could be 60 .lbs of seat pressure reduction.
THIS is why EMAP is my concern.
Lance
Thanks Lance. I don't know why I didn't see there was another reply. I missed why you used .64" for the exhaust equation as I got 1.28 as the square root of 1.6, but you halved that to .64. What spring pressure would you recommend that would cover my turbo setup on the exhaust side?
Also, since I already have custom Smith Bros pushrods, I need to make sure the geometry stays the same. It's only the installed height I need to worry about there, right? The current springs are showing an installed height of 1.880". How much leeway do I have there? +/- .1", .2", etc?
As mentioned the valve is still the same so the valve spring itself does not affect the "geometry".
The difference between springs would be the "installed height" of a particular spring. You use a spring height tool to first measure how much space is between the spring locator and retainer (without spring). If you have a spring that specs for a 1.800" installed height and your measurement without the spring is 1.830" for example then you would add .030 amount of shims under the spring locator and then install the spring.
Installing a spring with advertised spring height of 1.800 shorter because stock heads are set up for 1.750 ish means the spring is installed a little "tighter" and its seat and open pressure would be higher than it would be if it was installed at 1.800". In many cases this in itself is no big deal as long as that slightly shorter installed height does not get the coil into bind if the lift of the cam exceeds the spring rating max lift, which will degrease, with a shorter installed height.
Often heads get their spring pockets machined down some to accommodate aftermarket springs with installed height specs of 1.8xx and higher. Shims of various thickness are used under the spring locator to get them dead nuts on what the installed height should be for that particular spring.
Whatever new spring you get, just be mindful of what installed height it should be and install accordingly. Your valve train geometry, thus PR length, will remain as it is now as long as the same valves and seats are on the head. Change the later and you would then need to confirm PR length
As mentioned the valve is still the same so the valve spring itself does not affect the "geometry".
The difference between springs would be the "installed height" of a particular spring. You use a spring height tool to first measure how much space is between the spring locator and retainer (without spring). If you have a spring that specs for a 1.800" installed height and your measurement without the spring is 1.830" for example then you would add .030 amount of shims under the spring locator and then install the spring.
Installing a spring with advertised spring height of 1.800 shorter because stock heads are set up for 1.750 ish means the spring is installed a little "tighter" and its seat and open pressure would be higher than it would be if it was installed at 1.800". In many cases this in itself is no big deal as long as that slightly shorter installed height does not get the coil into bind if the lift of the cam exceeds the spring rating max lift, which will degrease, with a shorter installed height.
Often heads get their spring pockets machined down some to accommodate aftermarket springs with installed height specs of 1.8xx and higher. Shims of various thickness are used under the spring locator to get them dead nuts on what the installed height should be for that particular spring.
Whatever new spring you get, just be mindful of what installed height it should be and install accordingly. Your valve train geometry, thus PR length, will remain as it is now as long as the same valves and seats are on the head. Change the later and you would then need to confirm PR length
Awesome bit of info ******. They definitely points me in the right direction. This is the only change I'm making to the motor while it's apart, so the help is greatly appreciated. Thank you!
Hi Snorkel, provide your spring DATA and I can do an EAP model to state Valve float vs I/E pressures.
I would need to know the Cam specifications, the rest is in the can.
10-31-2017, 12:55 PM
Valve Springs for High Boost 
