How much hp and torque do i need to get a dragster/or altered in the middle-to-high 8 second range? b) 9 second range? c) 10? The car will probably weigh around 2500lbs. It will probably be less, but i'm saying 2500 because i want to err on the conservative side. Most likely at this point iron headed sBC 3 speed. Traction won't be a problem because i can get pretty big slickwise. Willing to use whatever gear nessesary, but don't want to turn higher than 5500 rpm. Well, really 4500-5000 rpm.
my sbc runs about 8.40 at sea level with an alum head 383, 14:1 on alcohol with a PG and 4.56 gears on a 31" tire. roughly 650/675 hp @ 1850 lbs.
My old Moroso Power/Speed calculator (yep, got it laying here on the desk) says around 550 hp (rear wheel) for 9.50's and around 400 hp for 10.50's in a 2500 lb car. Oh, 8.50's takes around 800 hp. Larry T
that would be figuring everything is perfect with the combo....convertor, trans, etc..... and track and air conditions as well.....build for 750 and you can always back it down
If you want to run in the 9 sec range under 5000 rpm, you'll need a lot of cubic inches. Probably with a supercharger.
You are correct, alot of variables out there. The formula isnt perfect but it does get one in the ball park and lets him know that the figure that one comes up with is the minimum. He is about 750 lbs heavy for most dragsters/altereds so he can use those figures with a lighter car and hit the mark.
Why the 4500 -5000 rpm limit? Not that you can't do it like that, just curious... Do you have an engine family picked out? Good luck, -Abone.
the 5 grand rpm limit is mainly for reliability. If, however, i can get a setup that will go 6500 or even higher and still have reliability, then i'm cool with that. i'm not anti-rpm, i'm just anti-motor wrecking. The "engine family" will be SBC either iron OR alum head depending what i end up with.
how are you going to get a sbc powered altered/dragster to wiegh in at 2500? even using mild steel tubing, iron block, heads and intake you should be under 2000 lbs. are you using a manual or auto? if your going with auto you'll be wanted a glide, better stronger more efficient and faster too. with a sbc you'll be abler to turn 6500 easily, and it wont hurt anything unless your tuneup is way off. I have customers that run 8.90s in 2600 pound door cars with sbc's that freshen the motor every couple years, and these guys race a lot.
I believe this is another one of those hypothetical threads were everyone gives good, sound advice that gets dismissed then OP moves on to next fanciful idea. Like the "how do I get 500hp cheap?" and "how do I raise the red-line on a SBC without doing any work?" threads. How do I lower the ET on my non-existent dragster? I'm sure it's a piece of pie to get an over-weight dragster with a 305 turning 4500RPM into the 8's. Why are people wasting their time with blown Hemis...?
I am with Tinman here. No way an altered or dragster should come in at 2500 lbs. Carshopowner's dragster has 550 hp and weighs less than 1500 lbs without the driver and last weekend it went 8.8 at 149 mph turning less than 6300 rpm. As SixFive noted, do a little real world research before you start asking questions and making ***umptions as to weight and rpm limits. You suggested that you would use a three speed trans--auto or stick? If you want to go fast for cheap get some recent issues of Hot Rod magazine and learn how to build a turbo late model engine for very minor bucks, put a powerglide behind it and drop it into a light car. Roo
Our altered weight was 1350 with a small block chevy with aluminum heads. 355 chevy with 13:1 comp. and 4000 stall and glide. Ran 5:90 in the 1/8th on test and tune. Needed much more converter. Wrecked it before we got all of the bugs out.
there is no subs***ute for horsepower..Build the best motor you can afford ,and go out and have fun. Our BBC runs an easy 9;50's ,below 6,000 RPM's with a 32 " tire.
dreracecar I haven't seen that formula in ages I actually forgot it existed. Used to be on a paper in my tool box so I could convert people's lust for speed into numbers that could equate to dollars. I'll have to copy that down again. Thanks I have a low horse small block that has spun 7K pretty regularly for quite awhile. I wouldn't want to hold it at that all day but short hops it has been fine. The trick is balance and blue print, align bore, lightened valve train and the best quality parts you can lay your hands on. Jeff is correct you are not going to run 9s @ 5K. Altereds are high winding unruley beasts. Realiability is for street cars, breakin' one is also racin' I am afraid.
I'm with SixFive on this. Love it when guys pull a horsepower or ET number out of thin air, (or more likely their posterior anatomy), then wanna know how to do it - cheap and easy to boot! If you're serious, here's my recommendation. 1) Go to your local track. 2) See who's kicking *** in the cl*** of your choice. 3) Note what they've done. 4) Do the same thing, only better. See ...... easy peasey!
1) Well, "hypothetical" or not (kinda rude to say so) it's my money. i'd like to do things carefully if you don't mind oh great wrenchwizards. Please forgive a mere mortal like me (right). 2) i'm just saying 2500lbs because i would rather estimate on the conservative side. This way if it ends up being 1800lbs. then so much the better. Chromoly vs. mild steel notwithstanding, i'd like it to be mild steel. Seriously, if i appear to be **** it's because i like to be as careful and meticulous as possible especially when it involves large clumps of cash. Plus i really don't know much about engines, so the questions will probably appear to be annoying. You could always not click on the thread if this bothers you so much.
Although I doubt this will really come to fruition, here's a quick breakdown from my computer program For a 2500 lb. car; minimum HP to reach target ET 10 Sec - 450HP 9.70 - 500 9.20 - 600 9.0 - 650 8.85 - 700 8.75 - 750 8.60 - 800
why build it out of mild steel? the material cost is not that much different and if you go to sell it your gonna take in poop shoot. with a sbc and a glide your going to be around 1500 lbs, being conservative is fine but your off by nearly 1000 pounds. To get 2500 you could have 2 sbc-s, 2 cast iron glides, and a dana 60 rear and still be under that wieght lol.
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