FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Grbmaverickmo on February 06, 2014, 07:34:59 PM
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Is it capable to break into the 12`s with this combo? A fresh 69 390 gt with a lunati CJ replacement cam. A stock alum PI intake or blue thunder copy. A fresh c-6 with a hughs 3000 stall. and I`m torn between 3.91 or 4.30`s in the rear with cheater slicks. Car weight is 3600 with me in it.
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That should easily break into the 12s if you get traction. Go with the 4.30s, and make sure you have headers, not those horrible 390 GT exhaust manifolds.
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Two times that. My first car was a 68 fairlane, 390, 12 to 1 trw pistons, cj heads, 427f intake, 850, super comps, c-6, 3000 stall, 4.10 gears and still ran points. 12.0 all day long. Car had lots more in it but couldn't afford it at the time. Like jay said traction. Went from 14.11 street tires to 13.05 with 20 year old dry slicks.
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Ok cool. I`m sure I can hook it half decent I`ve built a few Mavericks with decent motors and got them to hook. I know this thing is nose heavy with a torque motor but I like the challenge
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How tall of a tire you going to run? I had 26 tall with 4.56 and ran out a good 200 foot from the stripe. Taller tire hooks better as well.
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26inch tall tires. Thats why I was going back and forth to get 3.91s or 4.30s
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I'm going to dig out the Moroso "Dream Wheel" and do a couple of calculations. I'm going to say you have 360 HP. At a vehicle weight of 3600 pounds, the dream wheel says you should be running right around 12.0 @ 109 MPH. Again, according to the dream wheel, at 109 MPH you will be turning just over 6000 RPM with the 4.30s, and 5500 RPM with the 3.91s.
Realistically, with traction challenges you may only get to 12.50 at 104 MPH. Then the numbers would be 5800 RPM and 5250 RPM for the 4.30 and 3.91 gears, respectively.
Assuming you have solid lifters in the engine and the engine can safely be revved to 6200 RPM or so, I would still go with the 4.30s.
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You know the whole ET calculator thing has never worked for me.
Example
My 01 Ford Lightning weighed 4800 lbs with me in it, my Dyno runs on the street tune showed 630 RWHP and the truck ran 10.47 in the 1/4. On the race tune with race fuel and an additional 4 lbs of boost I would see 708 RWHP the truck would run 10.13. If you run the race calcs they dont get even close to those ET's.
Like anything its a good base line, like a dyno sheet but the real world numbers at the track are a whole other deal. That TQ cure is very telling which is why I am such a huuuuge mod motor fan!
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I think supercharged or turbocharged engines throw those calculators a curve, because the torque curves are so broad and flat. They are really designed more for naturally aspirated engines, IMO. For what its worth, the Moroso calculator has been pretty close on my naturally aspirated combinations.
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I have always thought the same thing Jay, even to a point where I always thought why not another calculator for Force induction.
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I have always found the Moroso Power/Speed Calculator pretty much dead nuts accurate, IF the car is well sorted out. My Fairmont and Mustang both line up ET vs MPH wise perfectly, and although the Mustang is pretty well perfectly aligned with HP numbers as well, my Fairmont actually shows the engine makes a bit more HP on the slide rule than my dyno sheets show.
Most typical street/strip cars are at least 1/2 second slower ET wise, compared to their trap speed. And even being off by more than a full second is not unusual for a miloly geared car with street tires.
Now, whenever I tried some common website supplied computer calculaters , they were off by a mile. Some showed my Fairmont as having over 700 HP, about 150 more than it actually does. Also, the trap MPH is a much better HP indicator than ET. If I stuck a pair of 195 75R14 street tires on my Fairmont, it would likely still trap around 130 MPH, (if it didn`t crash!), but the ET and especially the 60 foot numbers would be absolutely terrible.
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This conversation has me very curious. I haven't been down a drag strip in 35 years, and back then it was just with our high school stock street cars for fun. I was thinking the car I just built would run in the high 14's. So here's my question.
My car weighs 3950 with me in it. It's a .030 over 390 with the 428 crank, (basically a 410 or 416ci) C4ae heads with 428CJ valves and performance springs. Lunati's version of the CJ cam. Edelbrock RPM performer intake, and 1407 Edelbrock carb. FPA shorty headers with 2.5 inch twice pipes. Pertronix ignitor and coil. A 4 speed close ratio toploader. A centerforce dual friction clutch set up. 3.89 rear end (one tire fire for now) It has 26.5 inch diameter, 8 inch wide old school cheater slicks.
Supposedly about 390 hp and 450 torque. What would you think it would run in the 1/4? What about if I get a posi-trac rearend?
Also, can you tell me about, (or point me to) this Moroso calculator? I've seen a couple of calculators here and there and thought they were very exaggerated.
Appreciate it, Dave J
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Careful, you can waste a lot of time on this thing ;)
http://www.summitracing.com/parts/mor-89650/overview/
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Thx Jay, this gives me an idea. "Fantasy drag racing". Like the fantasy football except you build your own theoretical car and race other drivers.
;0)
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To the original post.. I'm not sure 12's will come easy with your combo... Probably possible but I think everything would have to be perfect... Assuming a fresh 69 gt engine still has the unported C8AE-H heads on it? Those heads in unported form are gonna be holding it back... I don't think the cj cam is all that large either? Might only make peak power at 4800-5000 rpm? I hope I'm wrong but I'm thinking the current combo might be closer to the low 13's.... Good luck and let us know how it turns out...
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ok cool thanks. Yes those are the heads I`m using and yes there unported. I was torn between the Lunati CJ cam and the smaller Crower stage 5. I wanted to stay around the 220 to 230 split range at .050 duration and .500 lift the CJ cam had that were the Crower was .449 and .550 ish sorry forget exact didn`t want to get into alot of lift and need diff rockers and end stands to handle heavy valve springs. I`m hoping it will turn 5500 thats as high as I`m gona shift it no matter what. This is my at the moment motor for the FE race at Beaver Springs. I have a 63 406 trip motor thats gona be my spend big money on and do all out hopefully for next yr. I kinda thought low 13`s myself just out of experience building small blocks. Its gona go in the 12`s at that race cause I`m gona spray it that day lol it wont have a choice. Thanks for the help on this and I will def share what happens