63mako

Both depend on static compression vs DCR. That is fine if you are running low compression and limiting your rpm. (mild street build). We are talking about an 11 to 1 600 HP small block engine that pulls past 7000 RPM. In this motor you have 2 choices if you want to run pump fuel and maintain a given DCR. Increased duration and tighter LSA. (less streetable) Decreased duration and wider LSA. (More streetable) Both will achive the desired DCR. To far one way or the other is detrimental in different ways. The key is to come up with the best combination of the 2 that will give you the power and manners for your intended use in the design stage of the engine build. Telling people a 107 LSA is the magic number is rediculous.

rham

I agree that saying 107 is the magic number is wrong, except in certain combinations. My question is, lets say in your engines situation could you have made the same power by having less static compression, less duration and a tighter lca putting your overlap where it is now? When looking at different cam companies cam specs hardly any compare different lca's with the same durations and lifts. For instance Comps line of Extreme Energy cams is ground on 110. For my circumstance where I plan to have a 9:1 350 with good flowing heads, exhaust and dont want to turn over 5700 or so, how do I know that a 268 single pattern ground on a 108 with 4 degrees advance would not make more power than the Comp Extreme 268? That would put me at 52 degrees overlap which is very streetable. Most of my experience is dirt track and a few very mild street cars so I am looking to get the most out of the cam I choose. Unless you have access to a dyno or a lot of real world experience with a dyno then we are at the mercy of the cam companies and what we are able to read. Even most cam companies tech help are reading off a chart that decides the cam you need, they are not cam experts.

2000FRCZ19

for a given comp ratio, say mine is at 10.5 to 1. if i were to take my build and go lower with my duration and lower my lsa i would not be able to drive it on the street with pump gas. it would detonate like crazy due to rasing the dynamic comp ratio. i am very close to the limit with my dcr. lsa is a tool, not the end all component for power. i picked an off the shelf cam that had been used in similar builds to suit my power goals and driving style. i then played with lsa to optimize the dcr and to get the tq to come in a little earlier. i wanted my power to peak a little eariler also. i had the cam ground on a 108 lsa. that should give me a little more power due to the raise in the dcr over the original 112 lsa that was on the similar builds and it will get my power where i want it. i will however have a little rougher idle but i do like that so it isnt a problem for me.

cardo0

The original post was a LSA comparision on a "stout sbc" and 540 Rat made a great effort to provide alot of good information. It somehow became how to make a 600hp hi-po sbc streetable. Now its become what a obscure Pro Stocker uses in his mountain motor. Anyone here running a Pro Stock mountain motor on the street? BTW i saw the Loch Ness monster chasing Big Foot out of Seal Beach inlet this moring.

Well i don't call 110* a wide LSA for a sbc.

So lets look at what the cam mfr's are selling for the sbc. All Comps pro street cams are 110*.:o Now Isky really got it wrong then as all thier solid roller cams are 104* to 108* LSA.
Hey take a look at Lunati "Street Master" cams and Lunati "Street/Strip" solid cams - all 106* to 108*. BTW all Luanti sb "Drag Race" cams are 106 LSA.

How did all those companys with all thier resources and equipment get it wrong when we can chalkboard talk it right here on the internet? Guess all those cam mfr's need to read this thread or they'ell go out of business.

cardo0

63mako

Is it relevant to talk about streetability with this motor? If the discusion is totally about what cam makes the most peak power and torque in this particular build the 107 wins. The 113 loses by 3%, the 110 is the worst performer.
There are few building a 600 HP hydraulic roller strip only motor that runs on pump fuel. Just to play it is ok but you won't be competitive. So it would be safe to say this would be a street/strip build. For the novice building a street/strip motor following this formula as a build blueprint most would be much happier with a 113 LSA and giving up 3% of his power from 2500 up to be able to still safely run pump fuel, vacuum accessories and have decent off idle throttle response compared to the 107. That guy will also put the majority of his time behind the wheel in on the street, either cruising in town or running down the highway in high gear and a lot of them won't have optimum gearing to use the 107 cam effectivly in those situations. What percent of your driving is really at WOT?
Cam companies are at the mercy of the magazine testers and the average joe. Engine builders are in the same boat. Dyno results are the total picture. Dyno charts always start above 2500 RPM. If the 107 cam makes 3% more power on the dyno chart from 2500 to redline that is what the cam company and/or engine builder builds because the guy reading the article or advertisement wants that high peak dyno number. Your average gearhead doesn't realize what that gives up in streetability in an on the edge build in the area below 2500 and in an off idle and sub 2500 RPM highway part throttle operation. Just trying to help inform that guy of his options, which is a lot of those reading this.