Custom vs Catalog Cams

[ClassAct]

THANK YOU. That's why RPM is so important. It's getting things done quickly that makes the car go quicker. Doing more work in less time equals quicker E.T.'s and quicker lap times. More RPM equals more gear. More gear moves the car quicker.

Yep, if you're geared to turn 4,000rpm, and I'm geared to turn 8,000rpm, I only have to make over half as much torque as you, to beat you.
That's why we calculate torque at a given RPM.

Tell that to the guys in Daytona Prototype that couldn't catch the turbo diesel that were running very low rpm or the drag racers that get out et'ed and mph by the higher tq cars running 3.40 gears... the combination plays a big part into what works.

Higher tq will pull a taller gear and make more wheel speed.

Go tell that to the Pro Stock and Comp Elimininator guys. Diesel is another deal. I don't care about what a diesel does. Hey are dirty, nasty pigs. They are for hauling 80k pounds of junk around. They ain't racing engines.

As to your drag reference, the gear you can pull is related to RPM and HP. Not torque. If you make enough HP to pull a 3.40 gear, that's all you need. Torque didn't matter.


Take two engines. One with 425-430 HP and let's say...800 FT pounds of torque and the other with say 800 HP and 550ish TQ and tell me which one will be quicker. Every single time, the HP will out run the TQ. Every time. All the time. All day long.

[CamKing]

I look at that a little differently. In that all torque should count the same. 10 lbft @ 2500 RPM is 4.76 HP but 10 lbft @ 6500 RPM is 12.38 HP.

But it's not. 100ft/lbs at 2,500 will not move the vehicle as fast as 100ftlbs at 6,500. That's the whole reason the calculation for HP was invented.
You have to include the RPM into factoring the performance capabilities of an engine.
Average power, thru-out the powerband, would be the thing to measure, when looking at a common pwerband.
BTW, I think that's what they do for the Race Engine Challenge.

Thank you, Camking.

It's just simple math.
For those that can't grasp it, try calculating torque at the wheel.

[Stan Weiss]

The low RPM torque will do more for me moving away from a stop light than the high RPM HP which I will only see at the track.

Not if the other engine's power curve allows for a different gear ratio, and leaves 1,000rpm higher.
Your low RPM torque only wins, if they have to run the same gear, and converter.

Mike,
Stop light / traffic light. Some people drive their cars on the street / highway (also what gas mileage) and only now and then take them to track.

Stan

[Stan Weiss]

But it's not. 100ft/lbs at 2,500 will not move the vehicle as fast as 100ftlbs at 6,500. That's the whole reason the calculation for HP was invented.
You have to include the RPM into factoring the performance capabilities of an engine.
Average power, thru-out the powerband, would be the thing to measure, when looking at a common pwerband.
BTW, I think that's what they do for the Race Engine Challenge.

Thank you, Camking.

It's just simple math.
For those that can't grasp it, try calculating torque at the wheel.

I do it all the time.

Stan

ab-sw-90l-lines-gears.gif

[GARY C]

Yep, if you're geared to turn 4,000rpm, and I'm geared to turn 8,000rpm, I only have to make over half as much torque as you, to beat you.
That's why we calculate torque at a given RPM.

Tell that to the guys in Daytona Prototype that couldn't catch the turbo diesel that were running very low rpm or the drag racers that get out et'ed and mph by the higher tq cars running 3.40 gears... the combination plays a big part into what works.

Higher tq will pull a taller gear and make more wheel speed.

Go tell that to the Pro Stock and Comp Elimininator guys. Diesel is another deal. I don't care about what a diesel does. Hey are dirty, nasty pigs. They are for hauling 80k pounds of junk around. They ain't racing engines.

As to your drag reference, the gear you can pull is related to RPM and HP. Not torque. If you make enough HP to pull a 3.40 gear, that's all you need. Torque didn't matter.


Take two engines. One with 425-430 HP and let's say...800 FT pounds of torque and the other with say 800 HP and 550ish TQ and tell me which one will be quicker. Every single time, the HP will out run the TQ. Every time. All the time. All day long.

A real world example I know of, 2 equally prepared 23 degree headed 421 Nova's, both dynoed within 25 hp and tq of each other, both were the same weight, converter, shocks, springs, one had had a 1.69 glide and a 4.30 gear, the other had a 1.76 glide and a 4.88 gear both were very close NA but the car with less gear was quicker and faster by about a tenth or 2 at a lower rpm, both on a 175 shot it was 3 to 4 tenths quicker, on a 225 shot it was 5 to 6 tenths quicker and always out mph the other car.

Before Roy took gear out of his car it ran the slower times of Scott's car... I don't think it's one or the other, I think it's about power management if your going to get a 3100 lb leaf-spring car to run near 5.00's it takes a complete package, upward motion at the starting line is wasted forward motion.

I could give at least 5 other real world examples of high tq cars going faster by reducing gear and increasing wheel speed but you have to have the tq to make it work.

[hoffman900]

There is a reason every single race engine builder is looking for MORE rpms. It’s about as much torque as you can make at as high of a rpm as you can that wins races.

Think a restrictive plate engine and how much goes into developing them to rev beyond where they choke off....

[Stan Weiss]

Not everyone want to check valve springs every so often. Some people want to go 50K miles or more. Have the power brakes work and use the A/C all while get some kind of gas mileage and still have improve performance.

Stan

[ClassAct]

Tell that to the guys in Daytona Prototype that couldn't catch the turbo diesel that were running very low rpm or the drag racers that get out et'ed and mph by the higher tq cars running 3.40 gears... the combination plays a big part into what works.

Higher tq will pull a taller gear and make more wheel speed.

Go tell that to the Pro Stock and Comp Elimininator guys. Diesel is another deal. I don't care about what a diesel does. Hey are dirty, nasty pigs. They are for hauling 80k pounds of junk around. They ain't racing engines.

As to your drag reference, the gear you can pull is related to RPM and HP. Not torque. If you make enough HP to pull a 3.40 gear, that's all you need. Torque didn't matter.


Take two engines. One with 425-430 HP and let's say...800 FT pounds of torque and the other with say 800 HP and 550ish TQ and tell me which one will be quicker. Every single time, the HP will out run the TQ. Every time. All the time. All day long.

A real world example I know of, 2 equally prepared 23 degree headed 421 Nova's, both dynoed within 25 hp and tq of each other, both were the same weight, converter, shocks, springs, one had had a 1.69 glide and a 4.30 gear, the other had a 1.76 glide and a 4.88 gear both were very close NA but the car with less gear was quicker and faster by about a tenth or 2 at a lower rpm, both on a 175 shot it was 3 to 4 tenths quicker, on a 225 shot it was 5 to 6 tenths quicker and always out mph the other car.

Before Roy took gear out of his car it ran the slower times of Scott's car... I don't think it's one or the other, I think it's about power management if your going to get a 3100 lb leaf-spring car to run near 5.00's it takes a complete package, upward motion at the starting line is wasted forward motion.

I could give at least 5 other real world examples of high tq cars going faster by reducing gear and increasing wheel speed but you have to have the tq to make it work.

This is too easy. That's 100% chassis. Period. That's all that is. I was around and living when the giant switch to the powerglide was going on. Since that time, at any local track across the country you can find guys who have no idea of chassis tuning. And you can't help them. The PG fixed junk chassis issues and piss poor tuning.

You had chassis issues. Period. Don't bother to try and convince me otherwise. I can drive 15 minutes from here on Friday and watch dozens of cars that are pissing ET right out the widow with junk chassis, zero tuning, 90/10 shocks and the like.

Chassis tuning is a dying art.

[CamKing]

Not everyone want to check valve springs every so often. Some people want to go 50K miles or more. Have the power brakes work and use the A/C all while get some kind of gas mileage and still have improve performance.

Stan

That I agree with 100%
That has nothing to do with performance, or if a low RPM engine, can compete wit a higher RPM engine.
That’s just about giving up performance, for reliability, and comfort.

[SchmidtMotorWorks]

Jon, are we answering your question in the manner you'd intended?

That's not a snarky comment; I'm curious to see where you're headed.

Not really.

I understand the advantages.

My question is more about the point of decision for the customer to stop looking at catalogs and order the custom cam.

What motivated the decision to fork one way vs the other?

For example, I find myself influenced by convienience more and more. I wonder how much of an influence that is, just order something at 10pm Sunday night because you know you won't have time in the day for the forseeable week to fill out a form or answer questions.

Maybe people worry about price, but don't know the difference exactly.

As Mike mentioned, need to get it quickly.

[GARY C]

Go tell that to the Pro Stock and Comp Elimininator guys. Diesel is another deal. I don't care about what a diesel does. Hey are dirty, nasty pigs. They are for hauling 80k pounds of junk around. They ain't racing engines.

As to your drag reference, the gear you can pull is related to RPM and HP. Not torque. If you make enough HP to pull a 3.40 gear, that's all you need. Torque didn't matter.


Take two engines. One with 425-430 HP and let's say...800 FT pounds of torque and the other with say 800 HP and 550ish TQ and tell me which one will be quicker. Every single time, the HP will out run the TQ. Every time. All the time. All day long.

A real world example I know of, 2 equally prepared 23 degree headed 421 Nova's, both dynoed within 25 hp and tq of each other, both were the same weight, converter, shocks, springs, one had had a 1.69 glide and a 4.30 gear, the other had a 1.76 glide and a 4.88 gear both were very close NA but the car with less gear was quicker and faster by about a tenth or 2 at a lower rpm, both on a 175 shot it was 3 to 4 tenths quicker, on a 225 shot it was 5 to 6 tenths quicker and always out mph the other car.

Before Roy took gear out of his car it ran the slower times of Scott's car... I don't think it's one or the other, I think it's about power management if your going to get a 3100 lb leaf-spring car to run near 5.00's it takes a complete package, upward motion at the starting line is wasted forward motion.

I could give at least 5 other real world examples of high tq cars going faster by reducing gear and increasing wheel speed but you have to have the tq to make it work.

This is too easy. That's 100% chassis. Period. That's all that is. I was around and living when the giant switch to the powerglide was going on. Since that time, at any local track across the country you can find guys who have no idea of chassis tuning. And you can't help them. The PG fixed junk chassis issues and piss poor tuning.

You had chassis issues. Period. Don't bother to try and convince me otherwise. I can drive 15 minutes from here on Friday and watch dozens of cars that are pissing ET right out the widow with junk chassis, zero tuning, 90/10 shocks and the like.

Chassis tuning is a dying art.

4.32 at 162... Power management.

[digger]

I personally don't like street car where I need to rev the hell out of it and run the lowest gear to get at the power even though that's the way to go the fastest it's not my perogitive when I drive a street car with manual trans.

So for me the EMC style cam is closer to what I want to have an engine good bottom end at the expense of some topend. Perhaps not quite to the same extreme as some EMC but not the typical street cam with wide seperation with all events compromised

[plovett]

The low RPM torque will do more for me moving away from a stop light than the high RPM HP which I will only see at the track.

Not if the other engine's power curve allows for a different gear ratio, and leaves 1,000rpm higher.
Your low RPM torque only wins, if they have to run the same gear, and converter.

Thank you again. I have been saying the same thing for a couple of decades now, but it has more power when you say it. Even big name reputable engine builders don't always get it.

paulie

[rustbucket79]

How many of you that are ordering custom cams actually spec the cam, how many rely on the company's expertise?

None of my customers do.
If someone calls me, and lets me know that they "Know" more about what their engine needs for a cam, I politely send them on their way.
From my experience, those are the guys that will take all the credit, if it works well, and blame the cam company, if it doesn't.
I want as much information about the engine, as the engine builder can give me, including any experience with other cams.
The data I collect in a year, on how engines react to cam changes, in a multitude of different applications, is more then most engine builders will learn in a lifetime.

So are you interested in looking at my combo and offering what potential ET improvement a cam change can offer? I’ve ordered a handful of custom grinds over the years from Comp, roughly half I had them spec, (used Tim Cole mostly) the others I chose from their lobe library and spec’d the centrelines.

[paulzig]

So for me the EMC style cam is closer to what I want to have an engine good bottom end at the expense of some topend. Perhaps not quite to the same extreme as some EMC but not the typical street cam with wide seperation with all events compromised

Im the opposite, even a street car with a shift point of 7000RPM which by todays standards is conservative I would take that 7000 point, get max HP to fall around 6000-6500 and have a 2500RPM band of 4500-7000 you wouldnt even bother or care too much about what happens below that point because if it makes good power above that then under 4500 will be perfectly adequate for stop light ---> stop light. It will still just make noise and smoke on the street if you give an excess throttle input anyway...