Valvesprings/Valvetrain for extreme duty NA road course use:

Discussion in '2011+ Mustang GT 5.0L Tech' started by captdistraction, Apr 11, 2019.

  1. captdistraction

    captdistraction Corner Carver

    there's a shocking lack of information out there about the coyote valve train and its requirements to work reliably in a road course environment. So much so to the point where people either are willing to guess and try random parts (usually at their own peril with mixed results), or stick with the factory or factory "racing" parts (usually at their own peril with mixed results)

    Doing my own research, I believe the PAC-1234x spring may have been used by Roush Yates Engines to build out their IMSA/PWC 302R upgrade engines. That information is unconfirmed but I've reached out to RYE.

    What I wanted to find out is have people successfully used aftermarket springs/retainers/valvetrain components for a length of time (aka, a standard racing engine service lifetime) with excellent reliability? I can count a dozen broken motors on here that had aftermarket parts there, (though as many if not more stock ones as well).

    Going back to the PAC spring, Its 240lbs/in, with a Seat Pressure 92 @ 1.575" (100 @1.500)
    and Open Pressure 200 @ 1.000" (though I've seen 218, 230 as well for different specs)
    (though numbers vary depending on install height, cam lift and other factors)

    The boss 302 oem spring (which can vary significantly) 67lbs (300N) to 157lbs (700N)

    its a bit of a jump and presents the following concerns:

    Will it bend or break the hollow valvestems of the boss 302 valves? (PAC says no, internet says maybe, 1 case of a turbo car doing such)

    Will VCT work with it? (some say yes, some say yes with less accuracy, my tuner says absolutely not)

    Are they a true drop in? (pac says yes, but recommends Ti retainers)

    I'm looking down this rabbit hole as one of my failures may have been related to a boss 302 valvespring failure (or float near redline). Obviously I can lower the redline and try to avoid the limiter, but sometimes in racing all bets are off and I want to engineer the strongest most reliable setup I can and then work on the driver as well.
  2. weather man

    weather man Persistance Is A Bitch S197 Team Member

    I would give Vorshlag Racing, a sponsor on here, a call.
  3. captdistraction

    captdistraction Corner Carver

    Their take is the boss spring and run a base GT manifold and build the car around that shorter powerband.

    Sent from my iPhone using Tapatalk
  4. Racer47

    Racer47 Doesn't have much to say S197 Team Member

    Talk to Livernois, they seem to have the only (or one of few) combinations that work. And get rid of the phasers.

    If Livernois won't sell the cams and springs, I'd call all of the cam suppliers and see what they have and what info they will share. There are only a handful of places actually making this stuff. Places like Livernois, Roush, Brenspeed, etc just have cams and springs made to their specs by the same places that make all the normally advertised cams.
  5. Juice

    Juice forum member

    Im running a stock GT coyote 100% unmolested. I chose not to go into the engine inpart for the stock reliability. And from experience, I live by "if its not broke, don't fix it"!

    My WGI HPDE events run 40 minute sessions. I dont want to lose track time for mechanical issues. So far I got 4 track days @WGI, and 2 @NJMP (30 min sessions) without issues. Engine has about 100k miles on it. :)

    IMO, once you start messing with engine internals, reliability can be affected.
    eighty6gt likes this.
  6. Racer47

    Racer47 Doesn't have much to say S197 Team Member

    IMHO, if you want to have fun racing and stop this cycle of months of building, then breaking and then back to months of rebuilding street car stuff buy this TA2 Mustang and sell what you have now. Racing is hard enough without constantly having to make or find custom or limited supply race parts.

    This car is fast and reliable. You could drive it without worrying about breaking your engine or trans or going off track and causing thousands of dollars of damage because its expensive street car body work not relatively low cost and easily replaced race car body parts.

    Sure $45k is not cheap but how much have you spent so far on your current car? How many races have you missed due to breakage? How many hours have you spent working on it? How much more money will it take to make this car a consistent front runner in ST2? How much will the next engine failure cost?

    Some guys like building their own cars, doing all the fab work, making custom parts, building engines, etc. But if you are in it to drive, than I think its time to take step back, look at the big picture and maybe change your direction.

    HPDE is not racing and racing stock parts will not be competitive.
  7. captdistraction

    captdistraction Corner Carver

    ironically, that motor later shortly failed, iirc.

    As fun as dropping $45k sounds (and would love to know where to find said $45k), I won't be doing that any time soon. Either way I have to fix this car to sell it or keep racing it, so the thread's chase for information is valid regardless of the ultimate end user it benefits. If I sell this car, I certainly won't get back into racing any time soon, if ever. I'd likely just pay off debts from racing and wash my hands of the mess; thus theres's a vested interest in seeing this through to some other conclusion.
  8. SilBult

    SilBult Junior Member

    Well you do have a bit of a dilemma. It sounds like you may be stepping away from serious racing fairly soon in any case and would be happy to just have the car running well and being fairly reliable. It also sounds like you would prefer to have the VCT working like a stock engine. Here is what I would do. Either buy a good quality spring checker or find a REPUTABLE machine shop that has one and will check springs for a nominal fee. Next check as many Boss 302 springs as you can afford to buy and find 32 of them that check within 5% of the rated 69 lbs of seat pressure at the correct installed height. With luck and the right dealer you MAY be able to return the out of spec springs for refund. Set the rev limiter no higher than 7,600 rpm and pull the valve covers regularly to inspect things. If the Ti retainers are within the budget they would help take some of the strain off the springs. Unfortunately the old saying that there isn't any such thing as cheap speed is all too true. Good luck.
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