How much engine do I need?

[Paul G]

How much engine I need may not be correct, more like how much engine do I want. Putting an engine build together starts on paper first. My goal is to run in the 11's. Without a goal, I think I could waste a lot of time, money, and effort doing things the wrong way, and then over again.

Is my goal achievable? Can I get in the 11's using most of what I already have? Except the 360, that is coming out for a big block replacement. There are lots of builds in the "proven engine" section. I am not sure if any of them will work with my set up?

The specs;
4500# car with my chubby self in it. (estimated weight)
3:91 gears
A518 OD auto with a 2500 stahl Hughes lock up converter
28" tall tire, 275/60-15
SS springs in the back
pinion snubber

The power steering, brakes, and A/C have to work
Must run cool and be streetable in the 115° summers

[Scaregrabber]

I recommend 500 cubes, decent heads, hydraulic camshaft, 3 inch exhaust as the basis.

Sheldon

[idahogrumpy]

     That transmission eats a fair amount of HP and the convertor is to tight in my opinion. You will have to have an adapter kit or ultra bell to bolt that trans up to a big block. The radiator will need to be upgraded as well. Somewhere around 600 hp should do it. No matter how you get there you will need good flowing heads, intake and exhaust system. I would seriously look at staying with a small block, because a big block requires you change just about everything. I love big blocks, and yes they make big power, if you can afford it by all means do it! As for the details of the build, how much money do you have to spend?

[Paul G]

Swapping to the big block is a fair amount of work by itself. I have done some research on that. Ultra bell, radiator, engine mounts, headers and exhaust. That by itself adds up to about $3000.

The small block can go to about 450 horse with a stroker kit and heads. Better than what I have but not worth the investment. 

[Cooter]

Better hope that 518 holds up to a 600 plus ft. Lb. Of torque at the track. I've been inside a few that gave up in 4WD apps. With nowhere near that torque.

[Paul G]

Swapping to the big block is a fair amount of work by itself. I have done some research on that. Ultra bell, radiator, engine mounts, headers and exhaust. That by itself adds up to about $3000.

The small block can go to about 450 horse with a stroker kit and heads. Better than what I have but not worth the investment. 

Better hope that 518 holds up to a 600 plus ft. Lb. Of torque at the track. I've been inside a few that gave up in 4WD apps. With nowhere near that torque.

Do you recall what the weak link?

[Cooter]

O/D section for one. One way roller clutch for another. Servo piston cracking. Valve body check balls beating up the separator plate.
there's a snap ring that under high performance(high line pressures) breaks the case.

[green69rt]

Thinking out of the box... instead of putting a lot of money in your existing car and trying to make it street and strip just keep you existing engine tranny combo with some cheap/mild upgrade.  Spend all those bucks (sounds like you are prepared to spend a lot) to find a lighter weight car (old dart, duster, etc) that's closer to what you want for muscle.   Now you have one car for comfort/cruising and one for cruising/strip.

[Paul G]

When I had the A518 rebuilt it was upgraded with some better parts. Not sure what he did to improve it? My request was to handle 500 HP/ft#'s.

[charger496]

   My '71 does pretty much everything you want yours to do. I have 3.23 in the rear, and just turned a 12.34 pass. I'm pretty certain that with a gear swap in the rear to a 3.91, I'd be in the 11's no problem. I have a gearvendors and not a 518 though. my  radiator is a re-cored brass and copper with 3 bigger rows. If I did it again, I'd go with a Griffin or BeCool giant aluminum one. In 90 degree temps with AC the car runs 190-195 degrees, which is tolerable. Oh, and it's a low deck 500ci stroker from 440source. Definitely go big block for the power and streetability you're talking about.

[Paul G]

   My '71 does pretty much everything you want yours to do. I have 3.23 in the rear, and just turned a 12.34 pass. I'm pretty certain that with a gear swap in the rear to a 3.91, I'd be in the 11's no problem. I have a gearvendors and not a 518 though. my  radiator is a re-cored brass and copper with 3 bigger rows. If I did it again, I'd go with a Griffin or BeCool giant aluminum one. In 90 degree temps with AC the car runs 190-195 degrees, which is tolerable. Oh, and it's a low deck 500ci stroker from 440source. Definitely go big block for the power and streetability you're talking about.

That is great info. Pretty much where I want to be. What horsepower and torque does your engine make?

[BSB67]

   My '71 does pretty much everything you want yours to do. I have 3.23 in the rear, and just turned a 12.34 pass. I'm pretty certain that with a gear swap in the rear to a 3.91, I'd be in the 11's no problem. I have a gearvendors and not a 518 though. my  radiator is a re-cored brass and copper with 3 bigger rows. If I did it again, I'd go with a Griffin or BeCool giant aluminum one. In 90 degree temps with AC the car runs 190-195 degrees, which is tolerable. Oh, and it's a low deck 500ci stroker from 440source. Definitely go big block for the power and streetability you're talking about.

That is great info. Pretty much where I want to be. What horsepower and torque does your engine make?

FWIW, there is a common misconception on gear ratio change and expected et change on street cars....generally speaking.  Gear change has little effect on a street car et when using a real street tire in a car that is already traction limited.    If you can mat the throttle at the starting line without tire slip, a higher ratio or looser convertor may help.  Other wise there is usually little et improvement without a tire change as well.

[charger496]

    Paul, my motor made 530 hp and 630 ft- lbs at the crank on the dyno with a holley 750. I have a QF 780 SS on it now, whether that makes a difference up or down... On the track, I've tried running street tires, but it's all smoke. I run a small 8 1/2 inch wide drag slick, and it hooks pretty well, but I drive it to the track, so I let it move a few feet before I put it to the floor to try and not break stuff. 1.77 is my best 60 ft time so far. I still think 11's are possible with proper gearing.

[BSB67]

    Paul, my motor made 530 hp and 630 ft- lbs at the crank on the dyno with a holley 750. I have a QF 780 SS on it now, whether that makes a difference up or down... On the track, I've tried running street tires, but it's all smoke. I run a small 8 1/2 inch wide drag slick, and it hooks pretty well, but I drive it to the track, so I let it move a few feet before I put it to the floor to try and not break stuff. 1.77 is my best 60 ft time so far. I still think 11's are possible with proper gearing.

Good luck.

What mph and car weight?

[charger496]

112 mph and around 4050ish lbs.

[BSB67]

112 mph and around 4050ish lbs.

that is what I figured.  thanks

[Paul G]

    Paul, my motor made 530 hp and 630 ft- lbs at the crank on the dyno with a holley 750. I have a QF 780 SS on it now, whether that makes a difference up or down... On the track, I've tried running street tires, but it's all smoke. I run a small 8 1/2 inch wide drag slick, and it hooks pretty well, but I drive it to the track, so I let it move a few feet before I put it to the floor to try and not break stuff. 1.77 is my best 60 ft time so far. I still think 11's are possible with proper gearing.

Those are the numbers I need to plan for then. I talked with a local machinest the other day. He is suggesting to stay just under a 10 to 1 bottom end, 505 stroker, Eddy heads, single plane intake, didnt get in to specifics on the right cam yet. He did say to stay mild with the cam, nothing too aggressive. Let the big cubes do the work. 

[firefighter3931]

My old 446 made 535hp/540tq and would typically run 114-115 mph and high 11's at 4100lb raceweight. The best it ever ran was 116.25 mph & 11.68 on a mineshaft air day 

If that car really is 4500 raceweight it's going to need a 600hp build to comfortably run in the 11's 


Ron

[justcruisin]

4500lbs seems pretty heavy, it may be depending on options. As a comparison for you my 71 r/t 440 auto with 1/4 tank of fuel weighs in at 3825lbs without me in it. It is lightened some with alloy heads and intake but otherwise it is stock.

[BSB67]

My old 446 made 535hp/540tq and would typically run 114-115 mph and high 11's at 4100lb raceweight. The best it ever ran was 116.25 mph & 11.68 on a mineshaft air day 

If that car really is 4500 raceweight it's going to need a 600hp build to comfortably run in the 11's 


Ron

Glad you said it.  Plus he's at a bunch of elevation, I think.

Sometime there seems to be a misconception that the larger motor by itself makes more power.   

Paul - Although I generally tell people to rely on there engine builder, I'm not so sure I agree with yours in this instance.  Get access to a desk top type dyno simulator and set all of the parameters that you think you want.  Then run back to back simulations changing only the cubic inches.   Let us know what you find out.

[charger496]

   Paul, weigh that car. I don't see how it could be 4500 lbs. On the engine, your RB will be similar to my low deck B, but with better geometry/ rod angle etc. You'll have 500ci and not be maxed out like I am. That said, our motors will be similar. Things I'd do the same are things like 1.6 roller rockers for a little more lift and I think it helps the torque curve. I used a Performer RPM which is a dual plane and better I feel for streetability. Some things I wish I did are gasket matching the intake, Doing AT LEAST a little polishing or port work on the heads, and although I do like the Lunati Voodoo cam, I'd go roller if I could do it over. Money probably made that a non-issue at the time. I think BRB67 doubts I can get 11's out of my car... We'll see. And if I do, I'll get around to this photobucket crap.

[BSB67]

   Paul, weigh that car. I don't see how it could be 4500 lbs. On the engine, your RB will be similar to my low deck B, but with better geometry/ rod angle etc. You'll have 500ci and not be maxed out like I am. That said, our motors will be similar. Things I'd do the same are things like 1.6 roller rockers for a little more lift and I think it helps the torque curve. I used a Performer RPM which is a dual plane and better I feel for streetability. Some things I wish I did are gasket matching the intake, Doing AT LEAST a little polishing or port work on the heads, and although I do like the Lunati Voodoo cam, I'd go roller if I could do it over. Money probably made that a non-issue at the time. I think BRB67 doubts I can get 11's out of my car... We'll see. And if I do, I'll get around to this photobucket crap.

I think the car will go 11s.  My guess is that you could get there without the gear ratio change.  I just don't think the gear is the answer.  Gear and tire, maybe.

[Ghoste]

It can be a delicate balancing act and there is almost never a magic bullet.

[moparsr2fast]

 4500# does seem excessive.. I'm pretty sure the wifes 06 Daytona doesn't even come in that heavy. 

[Cooter]

4500# does seem excessive.. I'm pretty sure the wifes 06 Daytona doesn't even come in that heavy. 

Weigh it with ful size dude and tank full of fuel. You'd be surprized. Hell, tge new Challenger weighs in @ 4150# right out the gate.