HP and torque relationship in a light car

[Tommy]

IMHO, peak horsepower matters most at top speed (e.g., trap time in the quarter). Consequently, it's not a factor in most street driving .... all if you obey traffic laws in the USA. Peak torque at the RPM you plan to be at when you want the most out of your engine is more important. In street driving a car as squirrelly as a Cobra, I'd say peak torque should be a big flat curve between 2500 and 5500 RPM. .... One man's opinion.

P.S.
There are two more times when peak HP matters. One is when you put it in your signature block on the forum, and the other is when you're trying to one-up your buddies at the cruise in.

[lippy]

My Cobra essentially has a race engine. Solid roller, big cam, power really comes on from 4000-7000 RPM. HP peaks at 637, torque peaks at 569. If you keep it below 4000 RPM, it is very tractable and drivable around town. If you want it to come on strong, drive it above 4000. I like it that way and so far it has kept me out of trouble with a bit less low end torque.

Btw, mathematically, HP = TQ * RPM / 5252. That is true for all engines, and why torque and HP are always equal at 5252 RPM. It is also why, for example, truck engines have a lot of torque but not a lot of HP because they need to produce torque at low RPM for towing but don't rev high. Race cars run flat out at high RPM so torque at low RPM is less important. It all depends what you are solving for, but the constraints are the same. In a Cobra, to me torque is somewhat less important because you just don't need that much for a light car to feel lively.

[Dwight]

I have a street Cobra

I have 350 rwtq at 2500 rpms
max of 416 at 4400 rpms
and 350 at 6000 rpms

great for the street!

I can cruise at 1500 rpms and once (only once) I saw it at 7000 still pulling like missile

I called my dyno guy and asked what he set the rev limiter at? He said 7500.
I run a SCT chip which overrides the stock ECU setting of 6250.

I had asked him to set it at 6500. I changed dyno guys.

Dwight

[Dwight]

I agree with Lippy
he and I were posting at the same time.


I can blow the tires off my Cobra with easy.
I made modifications the my throttle system to give me more gas pedal, better control.
I run the best tires I can.

Half throttle in first
3/4 in second
and when I get into third a little I can go wide open


I build a 347 for my GT 40 last year and modeled it after my Cobra motor. I called Comp Cams and gave them the serial number of my Cobra cam and told them I wanted to move the tq and hp up a thousand rpms. I think I can give up torque on the low end because of the low gears in the Porsche trannie. The 40 and Cobra weight about the same.

Time will tell if I chose correctly

Maybe this summer!!!! It's been a four year rebuild!

Dwight

[lippy]

Smart guy, that Gaz.

[mikeinatlanta]

I'm a bit fan of torque motors in a cobra. I find it quite useful when towing my pickup to the mud pulls or when my tractor breaks and I need it to plow the fields with it.

Still trying to remember the last time I heard a racer (in any autosport) saying: "Sure wish I had a lower reving motor". Then there was the cobra guy saying, "I need to get rid of this 600hp motor so that I can get more torque down low".