Ok guys. I just got the new Hot Rod magazine, and now I'm pissed/depressed/confused. Hopefully someone can tell me what's up. They build a 408 SBC that ends up making 651 HP, 555 lb-ft. I built an engine that is DAMN NEAR IDENTICAL, and with a th400 (coan 4000 converter) and 4.11 geared 9", it only made 400 HP at the wheels ( I was told about 525 at the flywheel), BUT the kid that dyno tuned it basically jetted the carb, timed it, and sent me on my way. SHORT BLOCK SPECS: <font color="red"> THEIRS: 400 +.040, zero decked, 6" rods, flat tops, speed pro Hellfire rings, 9.9:1 CR </font> <font color="blue"> MINE: 400 +.030, zero decked, 6" rods, flat tops, Total seal gapless 2nd rings, 11.6:1 CR </font> CAM CPECS: <font color="red"> THEIRS: Solid roller, 262/266@.050, .638/.639, 106 LSA </font> <font color="blue"> MINE: Solid Roller, 268/270@.050, .636/.636, 106 LSA </font> HEADS: <font color="red"> THEIRS: AFR 227 CNC 76cc, 309/230@.700, Crane wide body roller rockers (1.5) </font> <font color="blue"> MINE: BRODIX Track 1 CNC 64cc, 308/232@.700, TI retainers, Comp Cams Pro Magnum roller rockers (1.52)</font> INTAKE: <font color="green"> BOTH: Edelbrock super victor </font> CARB: <font color="red"> THEIRS: Holley 1150 Dominator, BUT they claim it made the same power with a 4150 </font> <font color="blue"> MINE: Race Demon 825 Drag Race Series </font> IGNITION: <font color="red"> THEIRS: MSD PRO BILLET with Digital 7 Plus with Pro Power Coil, 36 deg total </font> <font color="blue"> MINE: MSD PRO BILLET with 6AL with Blaster HVC coil, 36 deg total </font> OIL PAN: <font color="green"> BOTH: MOROSO 20191 </font> OIL: <font color="red"> THEIRS: Royal Purple 5w30 </font> <font color="blue"> MINE: Mobil 1 10w30 </font> WATER PUMP: <font color="red"> THEIRS: Meziere electric </font> <font color="blue"> MINE: CSI electric </font> Now if my motor did in fact make 525 HP at the flywheel, theirs made 125 HP more Sure they have 2 more cubic inches, but I've got almost 2 full points of compression on theirs. Is it possible the tune up could make a 125 HP difference??? WHY???
It is possible that they stretched the numbers in the mag alittle...sounds like you got a stout lil' motor there, whats it in?
was your motor "***embled" or lovingly built? the attention to details makes a difference. what about your oil system? lots of power there. cam degreed? you got a lot of compression, got enough octane? how about ignition? when you get to these power levels you would be suprised at the things that can **** up a lot of power in a hurry.
i wouldn't lose to much sleep over it, you cant compare ch***is dyno numbers against engine dyno numbers, if you want to compare your mill against theirs, yank it and send it to westech and have the same dyno operater tune and run the test that did theirs, then compare figures. ch***is dynos are great tuning tools, if used properly. which means run the vehicle, get a BASELINE, then start tuning on the combination and see if your numbers go up or down. but trying to figure all the losses running thru the drivetrain, converter ,weight of axle grease,etc,etc.is next to impossible. if you want hard horsepower numbers,you are going to have to strap the engine on a dyno,tune it for optimum efficency, and pull some runs on it,and get an some average horsepower and torque figures. for what its worth i have seen 2 different dyno operators pull the same engine and get different figures, thats why you want the same guy doing both engines for a comparison.
I had the short block built by Speed-O-Motive, but after some of the trouble I ran into I tore it apart and checked their work. All of the specs were perfect, believe it or not (other than them putting in the wrong rear main seal). I degreed the cam myself, it's installed "straight up". As far as the oiling system, I used the same exact pump and pickup as they did, the ones MOROSO reccomends with my oil pan. Like I said though, the kid that tuned it on the ch***is dyno jetted the carb (installed power valve plugs and fattened the jets WAY up?), timed it, pulled the plugs, said "they look pretty good", and sent me on my way. He didn't even put a probe in the exhaust!?! I was hoping we could've torn into it a little more and screwed with cam timing (I have a 2 piece timig cover and cloyes hexadjust timing set, and it is VERY easy to get to... woouldn't have taken much extra effort), valve lash, etc... I want to get every last bit of power possible out of it. I really feel like it has more potential. Anybody know of a good dyno shop in the Detroit area??? Preferably one that knows how to tune a Demon carb??? (the whole time that kid was tuning he kept telling me those carbs ****, throw it away and get a regular Holley!?!) BTW: it's in a 62 chevy II
i agree with racefab , you can't really compare engine dyno and ch***is dyno numbers. and there are a lot of factors like he mentioned,plus temperture and barometric pressue.....and the operator. what about your rear gear ratio? that will effect it too! i personally don't beleive everything printed in the magazines,i think they fudge things a lot
400 horsepower at the wheels is very respectable, they have a larger volume combustion chamber, more cfm barburator, and more ignition. but i think it maybe an issue with cam timming. but i'll bet your closer than the numbers say. you need the same person and the same dyno. and it's hard telling what rpm they pulled for that maximum number. jasper engines takes it to 7000 and if it blows it's your baby. so i wouldn't sweat it too much. i would say on the same dyno. you'd be with in 20 to 30 horsepower.
being on the same dyno would definatley change things but theres a pretty big number missing here flow numbers on both sets of heads, or are we ***uming both sets are run out of the box?
Too many variables. Everyone has hit on a bunch of important aspects. From ignition, to fudged numbers. They are selling a magazine right? Leme throw another at you. Hows the lower end set up. You know yours but what about theirs? Did they set it up loose, and will it still be running when yours is broken in? Probably won't account for over 100 ponies, but does add to the list of variables. Best bet is get 'em on the strip, hook 'em up and see who wins Or as someone else mentioned, strap onto the same dyno with the same tunner. Looks like you're doin' alright to me bro. Cruise it and tweek it 'til it does what ya want it to do.
Racefab nailed it. Flywheel horsepower and rear wheel horsepower are two different things. Given losses to friction and rotating m*** in your transmission, driveshaft, rear axle and rolling stock...I'd say that your motor is probably making close to the same flywheel horsepower that the magazine motor is claiming. In other words...don't worry about it...ya done good!
Ok, well it seems like you guys all think I did alright, so I'd like to ask again, does anyone know of a decent dyno shop (with a good tech) in the detroit area??? I really would like to wring every last bit of power out of this thing, but I'd rather not take it to the place I did last time. Anybody???
Ok, so I made some ***umptions on valve size, headers, and cam specs, but this is what I came up with FWIW.
Also you need to account for atmospheric conditions (feet above sea level, etc...). Where I work we deal with small engines but in testing we add so much (I'm not at work and don't have the formula) for elevation and compensate for it. We have even sent product to labs at sea level to get rated. This is not going to make up 125 HP but could make 20 -30 HP difference, then all the factors listed above, plus any thing the magazine people could fudge on could explain the difference. Sounds like you have a nice engine, definetly nothing to be ashamed of.
Do you have any contact info on them 12pack??? I'm gonna re-ring it (gapless top instead of gapless 2nd), and do some exhaust work (including quick time cutouts), and then I'll wanna get it tuned.
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