11-30-2013, 10:24 AM | #1 |
Not Yet Wild
Join Date: Oct 2013
Posts: 64
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Vegas Carts Performance Cam Specs
Geoff,
Quick question. Posting it here, because I suspect the answer will be interesting to more than just me. Would you explain your rationale for the tighter Lobe Separation Angle (LSA) on your performance camshaft as compared to the stocker? Stocker has a 110 degree LSA. Your Performance cam has a 104 degree LSA. What is the general effect on performance? I continue to see competing explanations on the effect, so I thought I would ask you (I'm guessing you probably have tested the theory, too). Duration and lift is easy, but LSA is a different matter depending who I ask. Thanks. Ernie |
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11-30-2013, 10:50 AM | #2 |
Gone Wild
Join Date: Oct 2010
Posts: 6,730
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Re: Vegas Carts Performance Cam Specs
Decreasing the lobe separation will usually increase the maximum torque, and bring the torque band down to a lower rpm range.
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11-30-2013, 11:04 AM | #3 |
Not Yet Wild
Join Date: Oct 2013
Posts: 64
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Re: Vegas Carts Performance Cam Specs
I frequently hear, all things being equal, tighter LSA tends to increase overlap and boost peak HP and move it to right. I'll be interested to hear Geoff's explanation on his cams, especially if he has some test data. Would love to see the effect on bigblocks like ours.
Ernie |
11-30-2013, 07:47 PM | #4 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,433
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Re: Vegas Carts Performance Cam Specs
Was a long time ago but building boat motors you wanted tighter lsa than a car engine, you could not make a car cam work in a boat. Boat needs torque low and long flat curve, peak hp is not as important if you can't get on plane because of the huge cam you are running. The lsa does change depending on the lift/duration even for a similar use cam. We had to use a tighter lsa because the large lift/duration lacked so much torque down low is how it seemed to work. For a more normal cam this may not be the case, we were over 500hp in a 454 before votec heads in a motor that wold run sustained WOT at 6-6500, performer rpm intake, etc. Idle was so nasty, we had to drill the plates in a 850 just to get 1K rpm idle lol, and those were twin bbcs, true music. With a single plane intake and bigger heads it would have had more top end, but torque is the game you can't go wot all the time and have to get out of the hole good, its not like a car.
http://www.compcams.com/Technical/FAQ/LSAproperties.asp |
11-30-2013, 09:12 PM | #5 |
Searching for The Way
Join Date: Oct 2009
Location: Medina, Ohio (NEOHIO)
Posts: 11,421
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Re: Vegas Carts Performance Cam Specs
Well the torque curve is directly related to the duration of the lobe seperators when the kineval valve is fully opened to allow the whatzitmakallit overlapper release valve to energize the .......
Man I'm confused....LOL! Are we still talking about golf carts? You guys are freaking crazy ! SUBSCRIBED! |
12-01-2013, 05:19 PM | #6 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,433
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Re: Vegas Carts Performance Cam Specs
For example with a car you only need a somewhat narrow powerband, you can use a cam that makes big power from say 5-6k. You could put the same grind in a clone motor and have similar results maybe with some adjustments due to port/valve design differences/etc. But say you run the clone in a gokart you don't want a short powerband because you only have one gear. You need torque to get off the line and around corners yet wind out on the top end for straights....where with a car you would be using higher gears not just more rpm to run high speeds.
Juggling around the lift/duration and lobe centerline and advance will change how the powerband works, you come up with a combo that works best for your needs/application. That is how we found out mercruiser marine had some of the best cams for boats, it was their business, just had to find the big ones they used. Which reminds me, I drove a new Focus a while back and it had DI and variable cam timing, and something like 11:1 compression on regular fuel. You can feel it change timing, thing had awesome torque for a 2.0L. I was pulling 40mpg on two lanes. It drove like a small V6, low rpm unless you really stepped on it and had no problem moving the car around. Might be a while to get that stuff on a clone engine..... |
12-01-2013, 11:43 PM | #7 |
Gone Wild
Join Date: Jun 2012
Location: Las Vegas, NV
Posts: 961
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Re: Vegas Carts Performance Cam Specs
Thats actually a misprint that I just noticed on the website.
Ive tested many many different cams and settled on 1 grind that I feel makes the broadest power and torque which works best for our application. 246 Duration , .330" Lift , 112 LSA If the cam were a 104 LSA it would have a very narrow & peaky powerband. Typically these cams are in the 110 range, it seemed like the 112 LSA carried the topend just alittle better but both had a very strong bottom end. The same cam with a 260 Duration has more top-end at the expense of low end grunt. The stock cams are 212/220 .250/.250 110LSA so I figured I wouldnt waste time with anything under 246 duration. -Geoff |
12-02-2013, 08:32 AM | #8 |
Not Yet Wild
Join Date: Oct 2013
Posts: 64
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Re: Vegas Carts Performance Cam Specs
Thanks, Geoff. That's kinda what I was figuring. All other things being equal, tight LSA tends to increase overlap, which contributes to a relatively poor bottom end, but tends to add power to the peak at higher RPM.
I will likely be putting in an order for the 246 Cam in the near future. Ernie |
12-02-2013, 12:20 PM | #9 |
Gone Wild
Join Date: Jun 2012
Location: Las Vegas, NV
Posts: 961
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Re: Vegas Carts Performance Cam Specs
Thanks Ernie,
Hows the engine coming along? -Geoff |
12-02-2013, 09:06 PM | #10 |
Vegas modded 420
Join Date: Jun 2009
Location: West MI
Posts: 15,433
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Re: Vegas Carts Performance Cam Specs
Here is some good reading, if you don't want to read that much then read the second post by Dennis Moore.
http://www.riverracer.net/forums/arc.../t-136497.html Pretty sure the early 502 cam is the ones we used in boats, but in 454s not 502s. |
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