Horsepower estimate?

-
Bl1zzard

Bl1zzard

Well-Known Member
Joined
Nov 3, 2007
Messages
194
Reaction score
125
Location
Calgary, Alberta, Canada
I bought a 1974 Dart Swinger non-running. My son and I spent the last 18 months getting the various parts and missing pieces to get it on the road. We have it running now, and it purrs quiet nicely. Can squeal the tires with half throttle. Here's what I know about it. 360LA rebuilt with a Mopar purple cam, stock heads, RPM Performer intake, Carter AFB 650cfm carb, Holley ceramic header feeding 2 1/2" pipes right out to the back. Tranny is a rebuilt 904. Stock driveshaft and 7 1/4" rear end. Stock steel wheels. Someone asked me what kind of horsepower I'm making. I'm guessing 300, but really I have no clue. What do you fine knowledgeable folks think it's making with that setup? As a bonus, what could I do to wake it up even more? I'm leaning to the old Carter as the weak point but you may have better ideas.

Thanks,

Rob
 
Which cam. Purple is a generic term for mopar camshafts.

Something around 450-470 lift, probably in the 300-330 range
 
Sorry no idea, idle is not really lumpy so I don't think it's a very radical cam, but it does sound nice and rumbly, definitely not stock.
 
275 -290 I don't see the combo of parts making much more.
 
Better heads will help wake it more, depending on the compression ratio and actual cam specs, but one thing I can guarantee is that 7.25 rear end ain't gonna last very long, upgrade that first before making any more engine upgrades, at least an 8.25 if not a Ford 8.8 or 8.75 Mopar. At this point I'd guesstimate it around 290 to 300 hp.
 
A stock 360 with headers and a four barrel is all over 300 HP. Now I'm talkin GROSS HP, not net. Like they were measured before 72, which is all I give a damn about anyway. lol So yours maybe somewhere around 330 or so like @crackedback said. But the torque is probably pretty substantial. I wouldn't be surprised to see it hit 360-375 LB FT, depending on the camshaft.
 
RustyRatRod said:
A stock 360 with headers and a four barrel is all over 300 HP. Now I'm talkin GROSS HP, not net. Like they were measured before 72, which is all I give a damn about anyway. lol So yours maybe somewhere around 330 or so like @crackedback said. But the torque is probably pretty substantial. I wouldn't be surprised to see it hit 360-375 LB FT, depending on the camshaft.
Click to expand...
Pretty good estimating Rob, pretty good...............

Let's put a mild 8.2:1 360 on the dyno.
 
Thanks for the responses. I have a list of projects, waiting on funding approval from the CFO, aka my wife. First up is suspension and the rear end. It's the only place the PO's haven't touched. Next, wheels and tires. Then, I'll see what kind of power I can get out of it with your suggestions in mind.
 
yep, real world #'s under 300Hp with a little throat work to the heads.
It takes a little more to reach 330 Hp.
 
In 1974; the bone stock 8/1 4bbl 360 with log exhausts,and 268 cam was rated at 240 NET hp. Some say to make that into crank HP, you can gross it up by 1/.85, so; ........ 240/.85= 282 .......... box-stock.
Now, IDK how accurate any of those numbers are, but I also know that the 5.2Magnum is rated 230 NET, with a lot less cam.
So now; add say a one-size bigger cam,headers and a full length 2.5" exhaust, and some decent ignition timing; Ima thinking that adds up to more than just 20hp crank. But I'm not willing to bet just how much more,lol....
IMO
You have close to the right engine package for street right now. Concentrate on gears and stall, and change the tune for them as may be required..

BTW
For a streeter, the 650 is about the right size, more or less. On the street you will not notice much difference with a bigger carb, until after about 4500rpm, probably in second gear (cuz you will be burning right thru first), so with 3.23s and 25.5" tires, that will be ~70 mph. With 2.76s, 4500 will be ~80 mph
 
330 horse@5000 ans 404 lb/ft @ 3000

Screw the horsepower, the torque is where it's at. Torque is what is measured by the dyno. The horsepower is just figured.
 
Interesting you can use the same basic combo on the Desktop Dyno but switch to a Chevy 350 and the HP stays the same but the Chevy has less torque by 10 lb/ft. Must be the rod ratio.
 
toolmanmike said:
Interesting you can use the same basic combo on the Desktop Dyno but switch to a Chevy 350 and the HP stays the same but the Chevy has less torque by 10 lb/ft. Must be the rod ratio.
Click to expand...

It's the stroke. 350=3.48" stroke. 360=3.58" stroke. That's .100". That's a great example of stroke adding torque.
 
toolmanmike said:
330 horse@5000 ans 404 lb/ft @ 3000

Screw the horsepower, the torque is where it's at. Torque is what is measured by the dyno. The horsepower is just figured.
Click to expand...
:realcrazy: :rolleyes: :D can you have one without the other ?
 
You must log in or register to reply here.
-

Back
Top