Not a roller, but I've run a 238/238 .558 on 108 solid and a 246/246 .510. on 110 Both solids. the 238 ran out of breath at 5400 with 3.91 or 4.30. The 246 comes on way better with 3.91, 2.47 1st gear (4 speed) but you may run out of breath with the 3.79 stroke. Schneider Cams is worth a phone call. the 246 is paired with 11.7:1 365ci and comes off the light exceptionally well in city driving.
Good Cam Choice?
- Thread starter siuauto
- Start date
-
Jersey Devil
Well-Known Member
I've tired the DV formula on different engines and his adjusting duration, instead of changing lsa. It only works for carb engines in a narrow dispacement/rpm window. Not EFI friendly at all.
They say the formula is for 10.5:1 cr.. Reducing the duration alot to get the vaccum/idle puts the dynamic compression WAY Too High. Not to mention the duration would be so short that it wouldn't even make the power @ the desired rpm.
There are ALOT of factors that the 128 formula doesn't take into account. The overlap chart is useless.
When that 128 formula video came out out and the posts started flying, all I said was this formula can’t be right for all aspects of racing and like you also said, F.I. engines, pressurized engines, road course, drag, endurance all need something different.
Everyone was flipping out on this. David was clear IMO that this formula works for what he said it works for. 10.5-1 NA Chevy engines.
In dyno tests that I seen, limited amounts, it seems to work fine enough for the MoPar engines. I’m sure there is an adjustment to be made for accuracy. Engine Masters have a few cam episodes and I’m pretty sure they tested this LSA and *I Think* one episode was on a RB MoPar.
It’s worth looking at IMO.
I think his overall philosophy that most don’t run a tight enough lsa is probably valid, but to make a simple formula for it, is probably asking too much.
Like you said there’s a ton of variables.
Last edited:
I take the 128 formula with the same grain of salt as the carb CFM formula. Fun to look at, may not give you the correct or best performing data from the output.
Jersey Devil
Well-Known Member
I've read most of the books he wrote over the years and plenty of other competion engine build and theory books. Have plenty of formulas and excel spreadsheets for calulating ho, cfm requirements, gearing, , dynamic compression, runner cross section & length to harness intake harmonics, desktop dyno programs.
Camshafts are the subject I want more info on but every source just repeats the Basic information. ALL the cam companies, don't respond to email or cam recommendation forms. The people on the phones have know clue when I ask them specific questions. They just want to "Push" a Shelf grind people.
90% of the combos guys are running on here won't work for what I want/ consider Daily Driveable.
I got through about 100 pages on this forum do far... I will just keep looking.
I came to the same problem, all you can do is read/watch as many builds that have dyno results and or track times, and look for the trends for the different cam specs.
I wish people did more drivability testing, when it came to builds instead of just dyno and or track results.
Problem is driveability is different for each person, even performance is, why a lot of these threads turn into debates.
Jersey Devil
Well-Known Member
Yeah, EVERYONE on here have Vastly different definitions of streetable/ daily driver.
I'm an "nformation junkie ", Ever since I was little, I needed to the whys and how things worked. Became a self taught engineer of sorts, which lead me to becoming a Factory certified BMW/ FORD Tech.
Working on a formula to find a safe overlap amount to beable to run All accessories for a given displacement, comp. Ratio, with A/C, P/Brakes etc.
More than likely I'll just have get multiple custom cams and test.
Got a good amount of info. from this SBM builder's videos.
Terry Brighton (Brightonracing)
This x1000
My tolerance of streetable is miles away from someone that thinks an XE268H or Voodoo 268 are crazy aggressive.
Racer Brown and Schneider will pick up the phone. No "off the shelf" grinds...
There comes a time where you need to find information directly from grinders willing to talk. This I have done but still refuse to make any specific recommendations on the net since text and not a personal talk can be very different conversations with the exact same words used. Opinions on streetable, idle quality, etc., vary to much.
I’ve had guys here suggest I read a few books and all of which I have read. They think one way I think another way and the OP looking for advice hates both of our suggestions.
It’s a no win.
If the basic info or an upgraded conversation doesn’t cover it, I get it. 100%! I’d say in this case since you know a few things and since you get frustrated by the forum help, then I suggest to you that your more than likely capable of making a good choice for yourself.
Absolutely! David himself said, but yet was ignored, when he gave the parameters of the formula.
Jersey Devil
Well-Known Member
I just got a recommendation from Howards for my 390, TFS heads, RPm air-gap, high10s/low 11scr build.
he original said their 241/247@0.050", 110LSA part# 770665-10, then switch to a 112lsa when I asked if it will still work with P/B.
Hydraulic Roller Camshaft; 1992 - 2002 Chrysler 5.2L - 5.9L Magnum 2800 to 6500 Howards Cams 770665-10 | Howards Cams
-
Similar threads
