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#81
03-22-2016, 10:46 AM
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Since I'll be over 11 to 1 compression with the 455 when we freshen it up this time I'm looking at the 60245 cam for it with Rhoads V-Max lifters.
With the current cam at exactly 10.99 to 1 compression it idles nearly smooth, with 13.5" vacuum at 750rpm's. With a little more compression I'm leaning toward the big flat tappet cam instead, more of a test than anything else, to see how much power it makes, and how well it manages pump fuel over 11 to 1 compression......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#82
03-22-2016, 11:06 AM
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But, I don't think I used the word "comparable" either....obviously a hydraulic roller is going to be different than a solid flattie. I think Cliff said that he didn't know how much extra duration to allow for when using a solid flat tappet. I posted up a build that showed that I can get the same (or a little higher) horsepower peak rpm along with more horsepower (comparatively speaking) with around 13 degrees extra duration at .050". I for one have had great results with solid flat tappets and don't mind a bit to use them. Of course you can't compare apples to apples against a hydraulic cam because of the duration that's eaten up by the lash, but to say that a SFT won't hang with a hydraulic cam is a false statement. |
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#83
03-22-2016, 12:36 PM
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Correct, didn't want anyone to think that I don't like or use flat solid camshafts. It's just that you are going to need to choose them bigger than you would a flat hydraulic cam to do the same thing.
IF I do any more testing in that area, we'd be replacing a 230/240 flat hyd cam with a flat solid around 245-255 to hopefully accomplish the same thing. For our build in question here, the SD 455 with some head porting and 4 speed application, we went with a 230/236/112 HR cam. It will have great street manners, nice idle quality, and broad/flat torque curve. I'm hoping to see peak HP around 5400-5500rpm's, and over 500ft lbs torque across most of the load/speed range.......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#84
03-22-2016, 05:07 PM
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#85
03-22-2016, 10:01 PM
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Very interesting post on LSA by Len Caverly
http://speedtalk.com/forum/viewtopic.php?f=1&t=46038 "I do Pontiacs and yes a 108 cam will out perform a 110 or 112 cam every time on a typical 455 street build. It may not idle better but will certainly perform better!!!! And if I am serious about a street strip build it will be tighter than that. Len C" |
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#86
03-23-2016, 09:31 AM
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Idle quality is important to most on a street driven car on a day in and day out basis. We also need to make enough vacuum to manage power brakes, and a good percentage of these vehicles have air conditioning.
I'll not argue with Ken or anyone else on cam selection, but there is no need for crappy idle quality in one of these engines, you can have good vacuum, and good street manners and still make plenty of power on the days you decide to go to the track. We have at this point half a dozen cars that we race out of this shop, from high 9's over 135mph to high 11's at 115mph. The only one that has a tight LSA cam is the 9.90 car and it has 14 to 1 compression to manage it, and the timing locked out for decent idle quality. All of the others, even the "little" 406 pump gas street engine that runs high 11's has a wide LSA cam, excellent idle quality and great street manners. We've played around with tighter LSA on a number of our engines, and have found that you quickly get a lumpy idle, noticeable "reversion" just off idle, increased fuel consumption, and they just don't drive as well in the "normal" rpm range. Acceptable, yes, as good as the wider LSA stuff, no. I'd also mention here that I've clearly showed with dyno charts that you can quickly get into BIG trouble with tight LSA cams in terms of being able to manage pump fuel and leave considerable power on the table with poor cam selection. I'm wanting to go back to a flat cam in my own engine. First I want to get away from the solid roller lifter on the HR cam "hybrid" set-up, and want to see if we can make the power and run as well with a flat cam compared to the HR stuff. Since a cam swap is about 3 hours worth of my time, not a big deal to do some testing with a big flat hydraulic cam, then go back to the HR if/as needed. I'm looking closely at the Ultradyne 239/247 cam, or the Crower 60245. Once I get my block checked out to see if it needs overbored, and select the pistons, compute the compression ratio, etc, I'll make a cam selection.......Cliff
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#87
03-23-2016, 09:50 AM
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I have never understood the fascination with running a solid lifter on a hydraulic cam. You lose effective duration by doing so and don't gain anything to make up for it.
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#88
03-23-2016, 09:57 AM
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Think I might like jabbering with this Len guy.
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12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct Last edited by Half-Inch Stud; 03-23-2016 at 10:08 AM. |
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#89
03-23-2016, 10:24 AM
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I don't think there's anything necessarily wrong with what Cliff has been saying, you just gotta watch about making blanket statements.
You can finagle the lobes around and come up with a tighter LSA and still have idle quality, etc. It may not be a 106-108, but saying nothing else works besides a 112-114 has proven to be a false statement. You also have to watch about saying that a wide LSA will make more power....because the stock and super stock eliminator guys will be quick to refute that one.... |
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#90
03-23-2016, 11:12 AM
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My brother has a very similar engine (both around 455 cu. in.) with a similar cam other than the LSA (my 114 LSA to his 110 or was it 108? LSA) and that mine has more lift (his is a 4-speed, and mine's an automatic, but we have similar gears and vehicle weight. If you were to ride in his car and then in mine, you would swear his could run away and hide from mine. His powerband is like a light switch and feels like it could rip the hinges off of he!! when it "comes on". Would his run down the 1/4 mile any faster? Maybe, maybe not, but that really doesn't matter to us- and also to what I would suspect is a great number of people, given the choice of an exciting ride or better 1/4 mile times. Truth be told, his car is a LOT more exciting to ride in because it feels so much faster. For me, it is a bit too loud and cantankerous (I am 5 years older, btw
 ) and you really need to pay more attention when driving it due to the "on/off" powerband. Don't get me wrong, there is still the thrill there, but to me it's kinda like "a nice place to visit, but I wouldn't want to live there" situatiuon. Mine is SOOO much easier to drive. I'm ok with that and he's ok with that. To each, his own- that's the beauty. He owns about 15 very nice muscle cars in addition to his more docile daily drivers. If he wants to drive a rumpity-rump rocket, he has that ability. For many of his muscle cars (most of them Pontiacs) he likes (ok, requires) a choppy idle and tire-melting torque. I like a choppy idle but I wanted more of a sleeper. So we both can pick and choose what we want with cam selection. Cool, huh? As long as he can run pump fuel and not deto, he's good. He doesn't care if his engine's power drops off faster and that mine will rev higher. Truth is, he doesn't want it to run past 5200 rpm due to the the stock rods, so why put power there? Just some somewhat-related random thoughts...
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#91
03-23-2016, 11:47 AM
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 is another's drudgery .Thank you for your post, I think it raises some very valid points.
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#92
03-23-2016, 12:22 PM
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Adding fuel to the fire for interest and conversation around the coffee table
Comments from Dave Bischopp... "For many years most of the street/strip stuff we built was 108-110 lobe seps and we made good power, but when we started going to wider lobe seps over 15 years ago we found we could get much better driveability, way less "stink" out the tail pipes and extend the rpm range, this was with flat tappet solid lifter cams. For most of the solid roller race stuff we still used 106-108 as we only had cast cranks to work with but once the forgings became available we started going to wider lobe seps and in a lot of cases less duration and ended up with more power and quicker ET's at the track with more rpm capability. I feel a lot of the gains we've seen with the wider lobe seps also has to do with the increased efficiency with the cylinder heads. No doubt you can make some great power with the tighter lobe sep cams (we ran a 104 LSA in our 65 GTO), but I found at some point you will hit a wall. I disagree with your statement that today's cutting edge performance is made with tighter lobe seps, the guys making big NA power are using wide lobe sep cams and turning big rpm to make the power they do and this isn't specific to Pontiacs." "I'm not suggesting everyone run out and slide 114 lobe sep cams in their engine. The reality is lobe sep isn't really what we should be looking at as overlap, valve opening and closing events is really what should be looked at and the lobe sep ends up being what it is, but of course when spec'ing a cam and choosing the lobes to run part of placing the cam order is to specify what LSA the cam should be ground on, trying to remember all those events off the top of your head for bench racing discussion would get a little confusing. About 95% of my customer base is street/strip guys, about 6-7 years ago when the economy was booming we had a lot more customers building higher end larger engines, but most still wanted pump gas as they wanted to drive their cars on the street." Source: http://forums.maxperformanceinc.com/...d.php?t=775018 The obvious, as eluded to within this very entertaining thread here, much depends on the combo and use. Personally we have run combos that have been very successful using solid roller cams with a 108 lobe separation. For us the 108 LS often being recommended by some of the best including Chris Mays at Comp and the fine folks at Bullet Racing Cams with UltraDyne lobes. .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
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#93
03-23-2016, 12:41 PM
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#94
03-23-2016, 12:47 PM
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Its all realize to the parts being used and the goal in mind. I have used as tight as 106 and as wide as 116. It really depends on the parts and goal. There is no set answer!
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#95
03-23-2016, 01:50 PM
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"When asking for recommendations here, one must always consider that not everyone is the same and one person's joy is another's drudgery."
I wish I would have said that in the first place; it would have saved me a LOT of typing...and I suck at typing. Last edited by tpssonic; 03-23-2016 at 01:51 PM. Reason: I suck at typing |
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#96
03-23-2016, 02:01 PM
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#97
03-23-2016, 02:06 PM
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+2
I'm not recommending anyone do anything here, just posting information on what we do here and why we do it. I will add this to the previous post about evaluating any of this stuff by the "seat of your pants"......it is highly flawed. To date absolutely, positively bar none the high compression 455 we built with the 247/254/108 LSA cam "felt" the strongest on the street of any engine we've done and any driving where you were blasting thru the gears to evaluate that engines power output. It was nothing less than EXPLOSIVE in the mid-range, idled extremely "rough" and TONS of "attitude" everyplace. Hitting it with full throttle and you thought it was going to tear your head off/throw it out the window, and throw all your insides into the back seat! However, that engine was the SLOWEST at the track of any of the 455's we've built and put into cars with plenty of gear and converter in them. When we replaced that cam with Dave's Road Paver cam, and his CNC porte #62's, not only did it act like we cut the balls off it, it was very mild and the power curve was so smooth and linear that is was actually somewhat "boring". Gone was all that quick power like you hit it with a 150 shot of nitrous, it just pulled hard everyplace, no rush of power anyplace. At the track it runs nearly a full second quicker in ET and a solid 7mph faster......so much for the "bling" that comes with 108LSA and evaluating how well that deal works by the "seat of your pants"......FWIW......Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#98
03-23-2016, 02:14 PM
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slowbird, like you said- it all depends on what you are trying to accomplish and people need to realize we are all not alike in our wants and desires (especially when what you need is not what you want- that is a whole 'nuther discussion.
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#99
03-23-2016, 02:19 PM
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#100
03-23-2016, 02:20 PM
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