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Motor and Drivetrain / Valve Lash and RPM
« Last post by fabr on June 19, 2019, 07:24:14 PM »
I found this short info article damn interesting. Note the bold red number. WOW!!! DAMN!!!! I had no idea anything ran that much lift. Inferring from the article that motor must run close to zero lash. This old nascar engine had almost no lash either.  I'm having a custom cam ground for it to make it a bit more suitable to fast duning/desert running. I'll know tomorrow what the lash spec will be for it. Got me really curious. Anyway,here's the article.


Competition valve spring design and its relationship to lash.

 

A chief misunderstanding of valve lash is how it correlates to rocker ratio. When you compare a 1.5:1 rocker functioning with lash of 0.015in to a 2.0:1 rocker ratio also with 0.015in lash, they are not the same. Given a common lash of 0.015in., the 2.0:1 rocker begins to move the lifter at 0.0075in compared to the 1.5:1 rocker where valve movement begins at 0.010in. Also, the speed of the ramp is changing. A camshaft designed for 0.015in lash but mistakenly adjusted it to 0.025in, would probably increase the speed of the moving parts by 20 times.

As engine speed increases, the valve train components continue to hit harder and harder, which causes them to distort more and more. They all bend: the rocker arms bend, the pushrods bend, the fork on the lifter bends, the camshaft winds up. As a result, valve train components are designed to operate at the engine’s highest rpm—this is the point where they cannot sustain further abuse.

Another misnomer is the relationship between the crankshaft and the camshaft. Though connected by a chain, the camshaft responds only to the clock on the wall. As engine speeds increase, mechanical activity happens faster in relation to the clock. So, this is why an engine spinning at 8,000rpm can operate with valve lift of 1.200in, whereas an engine turning 10,000rpm is likely limited to around 1 inch of lift. This is because there is only a certain amount of time available to move the valve, and that’s a lot faster in relation to the crank.

Joe Hornick has designed successful racing camshafts and valve train for both 903ci Pro Mod engines and NHRA Pro Stock engines. One of his most successful Pro Mod engines operated with 1.440in lift compared to a front-running Pro Stock engine with 1.190in lift. Because the Pro Stock engine revs so much higher, it operates with less lift—although valve speed remains the same.

Competition valve spring designers are obliged to move the valve train at its maximum velocity, and the best way to accomplish this is to integrate the spring’s natural frequency with the correct spring rate. Extreme spring pressure provokes excessive deflection in the valve train and when combined with a disregard of the spring’s natural frequency, the valve train doesn’t react well.

Source

Joe Hornick Enterprises
Mooresville, NC
(704) 664-7322
jheinc.com
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by dsrace on June 19, 2019, 09:50:12 AM »
carl....that did suck ! i believe the rec reg did it but i dont know for sure. i know you've got a damn busy 4 weeks ahead of ya but remember to yank that out and mail it to have it checked by bazzaz atleat. worst case they throw it away, best case they figure it out.

i just pulled mine out of the th'er last thurs evening.  i will be pulling the motor next week i believe. if enemy get that head ready then i will be swapping to a better head. i WILL BE setting cam timing with a degree ring as the head and block were decked .007 or .010 combined. i cannot find the paper work that i did save with that info. apperantly using the e bar method doesnt really work once the head and block have been decked. enemy figure out he was almost 1 tooth off checking with a degree ring.
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by Carlriddle on June 18, 2019, 04:56:06 PM »
I run a ga scirocco single pass. I upgraded fan (still didn’t shell out spall $$) but cooling is no problem even with the turbo now. I run separate oil cooler in front of rad. And on e85 too.

Really wish elec problem didn’t cut my trip short by a day or so. It was just getting into the fun boost area! 
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by dsrace on June 18, 2019, 11:25:16 AM »
The one pass or two pass debate to this day still rages on.

 ;D you bet your  beathorse.gif~c200  beathorse.gif~c200  it is  :nw  rofl rofl
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by fabr on June 17, 2019, 12:36:27 PM »
The one pass or two pass debate to this day still rages on.
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by dsrace on June 17, 2019, 12:00:15 PM »
higher cyl pressure does increase heat, on top of hotter exh temps and oil temps etc etc. this is where a great innercooler and e85 come into play for best results.  i run a 2 core 2 pass radiator on my turbo 4cyl. i believe it's  a 2 core, 31" x 16 or 17" tall and 2 pass.
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by big dave on June 17, 2019, 10:33:22 AM »
Thanks Big Dave. I had my finger on the "buy now" button on that radiator, but it was a little too big for my space. I bought a 16" X 29" X 2" with dual fans. I am guessing that yours is turbo. If so, do they make more heat than n/a? I plan on calling Outfront about safe rpm, but what is your opinion?
Yes mine is turbo. I would thank the add heat from the oil retuning for the turbo would add heat. as for rpm limit. mine is set at 6800 from outfront.
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by BrianN on June 17, 2019, 08:29:21 AM »
Thanks Big Dave. I had my finger on the "buy now" button on that radiator, but it was a little too big for my space. I bought a 16" X 29" X 2" with dual fans. I am guessing that yours is turbo. If so, do they make more heat than n/a? I plan on calling Outfront about safe rpm, but what is your opinion?
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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by big dave on June 17, 2019, 06:02:15 AM »
best bang for the buck. works great on my 2.5 suby. Aluminum 3 fans. I only run two fans and it cools it great. my scope gets in the way of the center fan. I run the 219.99 one the fans mounting system is better on it.  This is on Ebay.

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Chassis and Suspension / Re: 5 link rear sandcar suspension
« Last post by BrianN on June 16, 2019, 04:59:22 PM »
I just ordered a radiator twice as big. Dual fans. It would reach 210-220. I would just stop and the fan would take it back to 190 pretty fast. I never turned it faster than 4000 rpm. I have the Stinger ecu from John.
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