How would you build a low 10’s street car
the original question was
I’ve got a 68 340 barracuda with a 4 speed and 3.55 rear gear it’s got a cam just a touch above stock and x heads, also got an LD340 intake with carter 1406 afb carb basically a stock rig but also have the hi-po exhaust manifolds, I want to get this car into the 10’s and still be streetable, how would you guys go about this? I eventually may want to turn the car into a daily so if mpgs can be kept in mind with the aforementioned goal that would be a plus. I was thinking something along the line of turbos, overdrive and 2.91’s but I’m just spitballing and have no real knowledge of mechanics behind me
Most of these combos are a far cry from a 340. Which is never gonna get there , normally aspirated.
1970Boy said "I was thinking something along the line of turbos, overdrive and 2.91’s"
and IMHO, supercharging is the only way to go, turbo's being the most likely way to go.
But I would start with a low compression 5.9Magnum, for a lil more Effective Stroke, to allow a lil more stuffing room
And I would run an A500/518 for the overdrive, and a lot more gear than 2.91s. To get off the line nicely with that low-compression slug, your 3.55s will be just Ok, and they become 2.45s in .69od. So; 65=1900 in loc-up, with 28s, and that might bring the final-drive into a decent fuel-economy range.Yeah 3.55s sound all wrong for 130 mph.... normally aspirated. But for a turbo combo 130mph with 3.55s and 28s would be ~ 5800 in Drive,lol.
Since yur gonna need ~600hp, and the low-compression 5.9M 4bbl is gonna make maybe 280, yur gonna need to, more than double the horsepower. No problem, just crank up the boost.
If I was doing it; I might try something different, namely a remote mount turbo.I would chose the 360 strictly for the off-boost torque, cuz with a single remote-mounted turbo, it's probably gonna need a bit of work to spool the turbo up. I would prefer the extra cubes to a hi-stall. The lo-compression 340 might be a lil soft off-boost at zero mph, IDK.
Plus you can sell the good-running 340 for more than what you are gonna have to pay for a highly-recommended Magnum 5.9core, together with it's A518.
With adjustable boost, you can tame it for the street. And just crank it up at the track, until it blows. There's gotta be a low 10 in it somewhere.
but I too am "just spitballing and have no real knowledge of mechanics behind me"
For this combo, I would not use the A833/GVod combo , for a couple of reasons;
1) I hate the sound of that BOV
2) the turbo will fly thru the gears and you will keep missing the 1-2 shift, maybe the 2-3 as well,lol.I don't mean "missing" the shift exactly; I mean it comes up faster than you anticipated and she gets up on the rev-limiter before you know it. I hate that sound.lol.
3) I'm not sure you can afford the clutch it's gonna take to manage that beast, and getting off the line will likely be extremely inconsistent without it. Not to mention that it's gonna be real hard on the U-joints and driveshaft. Oh heck, hard on everything back there.
4) the OD is only .78; so 65mph with 3.55s and 28s will be 2160, which being 260rpm higher or 13.7% higher, than with the A518 , which could be ~ 7% less fuel economy. That could be 1 to 1.5 mpgs in steady-state cruising.
5) Forget using it as a splitter; the ratios with an A518 are not favorable to it, and the GV people told me that you can't backshift it under full power. That means you gotta lift-shift outta the split, and bye-bye 10.2..
As an example, I can barely keep up with my 430 hp combo; when the tach starts winding up it gets mighty busy on the stick, and timing the lift-foot. It's a lotta fun and all but there is no consistency to it. With just about 700 rpm drops tho, it sounds really sweet from the bleachers. The tach goes to 7000 and I shift by the Speed-O, cuz the tires never stop spinning, and the tach just stays on 7000, the useless POS.lol.
6) Clutches blow up
7) The A833 is gonna need to be slick-shift modded to slip into the next gear consistently. If you don't mod it, it could hang up, and if the gas-pedal is on the floor, then the turbo is gonna drive your rpm thru the roof. And if your gas pedal is not on the floor; bye-bye 10.2
8) The GV od must be protected from accidentally being engaged in reverse; That is instant death to it.
9) The driveshaft is really short. The pinion angle and front angle start playing off eachother, setting up an impossible to cure vibration. I don't think you could ever cure it with keeping the leafsprings.
10) I'll think of some more
If I had the money and drive; I think I would try to set up a staged system with a small turbo under the front passenger seat, or up in the fender behind the front tire, and the remote in the back somewhere. Then I might downsize to a 5.2Magnum. But I wouldn't be targeting a particular ET,
I just want about 360hp/450torque/30mpg combo and it ET's whatever.
Hey maybe a 340 would be fun, yeah a lil more room for 2.02s then. I think I still have one or two of those kicking around. maybe several even,lol.
