340 or 360 for bracket racing

[Littlestroker]

I know this question has been asked over and over again. I never really paid any attention to the responce because I only had 340 blocks. Now I have a 360 and a 340. I'm ready to build one. With your help I can make a decision. If you had both which would be your bracket bomber. It's going in a 70 dart

727 trans, 4.89gear,28.5x10.5,5500 convertor. All can be changed, but this is what I have now. It will be a 1/8mile race set up. Thanks

[wedgehead]

The 360 will have a bit more torque but I think the 340 has more to offer that more than outweighs that torque. You have the benefit of a forged crank rather than cast which makes a lot of difference. The stall you have will work a bit better with the 340. Now you'll have to be real particular about the heads. BTW, which heads do you have? What CR do you plan on? Whar times did you run with your previous combo?

[ohioDemon]

HI, either motor will get you fast. if you're gonna wind it up i'd go with the shorter stroke [340}.

if it's gonna see some street action, i do the 360

[madscientist]

Hate to burst bubbles, but I would pass on a 360 every time if I had the choice. Why? Because the 340 has a bigger bore, a shorter stroke and a better rod to stroke ratio. Don't listen to the chevy guys on this one. The exhaust side of the passenger car heads is so pathetic MoPar should be ashamed. And higher numerical rod ratios help both the intake and exhaust port deficiencies. Your loss of torque is meaningless with the 4.89 gear. Use atleast an 800 cfm carb and buy a custom cam, spec'd for your combo. Costs alittle more upfront, but well worth it.

Good luck.
M.S.

[70AARCuda]

If both engines were built the same...the 360 would win...20 cu inches and more torque.

[wedgehead]

70AARCuda, if I built a 360 & 340 no way would I build them the same. The 360 is built for torque and the 340 is built for HP. All the 340s that I've built will run around a 360 outside the 1/8 mi to 1000 ft. The 360 is finished at this point. At 6500 the 360 is maxed out but the 340 will make good power up to about 7500 witha good set of ported heads. The 340 is the ticket for a small block. It was once called the Little Big Block!! Wedgehead

[moparvicd]

The 340 will serve you well no matter what your setup is. it's the next best motor besides the 426 hemi that chrysler has put out

[70AARCuda]

Wedgehead, I was just posting my opinion, as we see everyone has one. If you can not get a 360 to make horsepower above 6500 rpm, then you should stay with a 340. Also, because of the longer stroke the 360 will always have a lighter pistons which allows a engine to accelerate fast. And if the engine is properly geared you would be able to use the torque of the 360 over a broader range.

My last 360 would run 7500 rpm thru the lights. I guess I should have been shifting at 6500, but what good would it be for me to have those W-2 heads on it for?

Also, horsepower is a function of torque, dont remember the exact equation.

[wedgehead]

Sorry 70AARCuda, didn't mean anything by it. "Ain't Nothing Personal", this is what I have painted on the side of my race car. This is all that I was expressing by my post was my opinion I thought. The larger bore of the 340 will help it breathe better than the 360, therefore will make better power throughout the power range, more area to combust more gas and compress more air. Whew, why so edgy. Wedgehead

[moparvicd]

no

[rumblefish360]

wedgehead;

You did seem to come off strong. Not for nothin, he's right about the equal built engines. The 340 would win in HP and the 360 in torque. If you know where to shift them, the torque from the 360 will win the race.
Things going for the 360 are lighter pistons and stronger torque curve that peaks faster than the 340.
Whom ever built your past 360's could not get them to rev over 6500 RPM's, (& make power) ethier ripped you off or does not know what he's doing.
Getting an engine to rev over 6500 starts with the cam and springs. Followed by the flowing air in and out of the engine.
Now if your going to tell me it has to do with stroke, I know a 392 whipping out 8500+ RPM finish line runs.
Now thats a smoking MoPar.
Also, the bennifit of a forged crank is good. One can be purchased for the 360 no problem. This I'm sure you know.
The cast crank is good till around the 600 HP level. After that, I would go forged for sure.
1 last thing. For a beginner or bugget racer, a 360 would be better due to a cheaper core at a local junk yard.

Either engine will do well. In Littlestroker's case, I'd do the 340.

Littlestroker, make a plan and stick to it.

[Leigh]

+.030. 11-1, .557 cam, M1 or LD340, r4780 or 3310, X or J heads, 3200 lbs, and you have a solid high to mid 11's 1/4 mile package depending on your chassis efficiency. I forget the 1/8 conversion formula, sorry. I have used both, and like both, but I would use the 360. Good luck in what ever you choose, and keep us posted.