The Dodge Challenger Message Board

Dave,
Have you had your motor run on a Dyno to measure Hp & Torque? If so, what did your motor generate? I just finished building a different 440 for my Challenger (original motor to sit in the garage) and just finished at the dyno shop and have HP & Toorque readings for both 4bbl intake and 6bbl intake and was wondering how the car will do in the quarter based on those readings. I was informed at the shop to expect mid 11's in the quarter if I can get it to hook-up decent (the big challenge). Here are the peak HP & Torque readings - What do you think?

4bbl 560 lbs torque at 4100 rpm
517 HP at 5600 rpm

6bbl 556 lbs torque at 4200 rpm
514 HP at 5500 rpm

I am also trying to decide on what gears to run with a 727 automatic transmission, 3:55 are what I am leaning towards since I do spend most of my time on the street.

Any thoughts on either subject would be appreciated

You do not say how stock your chassis is and how heavy your particular car is.

With a fair bit of weight reduction your car should run mid-low 11s. If it is as heavy as mine (just under 4000lbs wet with driver) then expect high 11s at best.

However it depends not just on using good sticky tyres or slicks but also a good suspension set-up and chassis connectors to stiffen the body.

I think if you just stuck that engine in a stock Challenger you will only run low 12s even with slicks.

You will also need to gear it right.

You think higher gears in the axle will give you better mileage on a long run? I doubt it. Not unless you are making gobs of torque at low rpms as well which is not likely.

For best mileage you need to be driving along at the same rpm as peak torque. The torque peak has been moved higher up the rpm scale to make more HP so you need lower gears in the axle so that the car drives where the engine is making torque.

You need a 3.91 or a 4.10 rear gear with this engine. That way you will get best mileage at around 70mph. You can work this out exactly by using my Math spreadsheet in the thread about horsepower theory.

You will also need the rpms up during street driving because you will need something like a 3000rpm stall torque converter.

As for my engine. There is only one dyno in my area that I know of. It is a rear wheel dyno and it only runs up to 300hp. My estimated engine power is derived from the only dyno that counts. The Drag Strip. The same Maths Spreadsheet tells me what the power is at the rear wheels on a run.

Here is a link to the power theory bit with the speadsheets.

http://challenger.mpoli.fi/phpbb/viewto ... 3936#13936

I have just been thinking about this again now that I have had a nights sleep and more time.

If we deduct about 75hp for losses in the trans etc we end up with about 440HP at the rear wheels.

In a 3950lb (with driver) Challenger with 4.10 rear gears and good traction you are looking at a 12.10 second run at 112.59 mph according to my speadsheet.

However if you look at the MP Power to weight Chart in the same thread it says 450 rear wheel HP in a 4000lb car will net you 11.5 @ 113mph. The mph is about the same you notice so the HP-MPH relationship is about the same.

Now that last figure is for a car with a perfect chassis/suspension set-up, 4.5:1 or lower rear gears, and a 4000 rpm stall torque converter so the car launches at peak torque.

So although the Power to Weight Ratio chart is a good guide to what is possible in a race car I think my Spreadsheet gives a more realistic figure for a streetable car.

Actually this chart shows you the difference between chassis set-ups for the same mph.

You should be running around the 113mph mark if your car is around stock weight so according to this chart you could be running anything from 11.65 to 11.95 on slicks and as high as 12.75 on street tyres.

Thanks for all of the information, now I need to sit back and think about it. Since I live in Minnesota and we are in the middle of our winter season (40+ inches of snow on the ground and temps in the low teens) I have plenty of time to think about spring. I guess we get spoiled in the states as it relates to access to dyno's. I have access to 4 or 5 different providers that have engine only dyno's and another 1 or 2 with rear wheel dynos within two hours of my house.

The car itself is stock as far as weight and set-up go. What is the base weight of the challenger? I can then figure out what to expect for total weight (too much since I need to lose some weight) and then start to use the calculators to determine better what to expect. How much does the gearing impact the ending speed at the strip?

Thanks again for all of your great insight on what to expect at the strip. I can't wait to get it there and see what happens

Between 3800 and 4000lbs. The best way is to take the car to a public weighbridge and weigh it with a tank of gas and you in it. Or maybe you car find someone that has four wheel scales like they use to set up race cars?

Lowering the rear gears will make you accelerate faster. Your top speed is limited by your rpms.
Your speed through the traps is determined by your HP. If you are making more torque because of the lower gears you will make more HP and so more mph at the finish line.

Read that theory, download that spreadsheet and play with the numbers.