Quicker setup: 1/4 mile

[Sticky Bumps]

Take this. Same motor, suspension, tires, just different camshafts.
4 speed auto, w/ a 3200 stall converter.

Which one of these would get you the quickest e.t.? We'll use: (green, red, blue)

I would tend to think the one with the most low end torque for quicker acceleration. Green

There are some fast times with "over-cammed" setups in the LS1 department. The intake manifold limits us to 4800rpm for peak torque. Seen on this graph the smaller cam, (green - 224 duration @ .05) even creates peak torque around this mark. It even has 4* of advance ground in, which drops the rpm band. So obviously, I'd think for a cam-only setup, they are all over-cammed. I've seen 220* @ .05 duration'd camshafts (x-er line of comps) create 400rwhp just as these did. It seems if the intake didn't limit rpm, that these sized camshafts would create peak in the 5000 rpm range.

I'm just wondering what is considered a reasonable trade off for low end torque for high end? Or in other words, is there a trade off that will give you quicker e.t.s when dealing with raw rear wheel torque. I know, the stall could be bumped, exc. but I'm more curious on the power aspect.

Kyle

[dbusch]

what are the specs for each of the three cams? I would like to think the smallest cam would have bettered all three in avg. power if it had been retarded 2-4 degrees, or given a higher ratio rocker...

[Adger Smith]

If you are going to make dyno pulls to show the difference in the power curves of each cam, then you need all the other parameters the same.
I see A/F ratio differences. If you had the A/F ratio the same for each cam change the torque curve might have been better on one of the other pulls. I have found a slightly rich mixture will produce a better torque curve. When going for HP at high rpm then run it on the lean side of A/F ratio. Looks like you have attained the lean Higher HP pulls. You can also use more timing lead with the richer mixture. Can you overlay the fuel flow over the air flow of each pull? You should be able to see why the A/F ratio chances.

[bill jones]

-Here's the way I look at it.
-the green line is going to be faster from 3200 to 5100 which is 1900rpm of the range or about 58% of the total rpm range if you run to 6500 rpm.
-Then from 5100 to 6500 is 1400 rpm worth or about 42% of the rpm range so I'd pick the green line as my first choice.
-Then I would think the red line would be the next best and the blue line would be the slowest et but maybe it would have highest MPH by a couple MPH.
-If you were to run the top rpm to anything less than 6500 then I would definetly start with the green line power, especially if this is a street driven car.
-One thing that you might could do is to advance the cam of the red line about 4 degrees to perk up that run.

[Sticky Bumps]

what are the specs for each of the three cams? I would like to think the smallest cam would have bettered all three in avg. power.... or given a higher ratio rocker...

I can supply .05 specs

Green 224/224 112 108icl
Red 230 232 112 108icl
Blue 23X 112 108icl (guess)

I was more interested in which would create a better e.t. mearily by looking at the torque curve (assuming everything is the same, but cam)

if it had been retarded 2-4 degrees,

Definetly.

Kyle

[Sticky Bumps]

Here's the way I look at it.
-the green line is going to be faster from 3200 to 5100 which is 1900rpm of the range or about 58% of the total rpm range if you run to 6500 rpm.
-Then from 5100 to 6500 is 1400 rpm worth or about 42% of the rpm range so I'd pick the green line as my first choice.

I gotcha.

you might could do is to advance the cam of the red line about 4 degrees to perk up that run.

True. These camshafts are already advanced 4*, but I understand what you mean. Personally I feel they are all to big, seeing as 4* of advanced was placed on all, and they still meet the torque peak limit of the intake manifold.

Thank you,

Kyle

[Sticky Bumps]

If you are going to make dyno pulls to show the difference in the power curves of each cam, then you need all the other parameters the same.

True. I was using the curves mainly to use as a comparison of which would create a faster e.t.


Bill Jones got the answer I was looking for.

Thank you,

Kyle

[Rick360]

We need to know the rear gear, trans ratios and weight to tell which would be quicker. HP at higher rpm would also help.

We need to know how long it would be in 1st gear basically, since that is the only gear that the green cam might accelerate quicker overall (3200-7000+?). In the other gears (from 4000-7000+? rpm) I think the blue cam would accelerate quickest.

The engine is significantly under-convertered for best performance. Normally an auto trans will fall back to ~stall speed after a shift. With this combo peak power is so far above the stall speed that if shifted @7000 it would fall back to 4000 with a 1.75 ratio change(700R4?). We don't know what the HP is higher up, but with this converter it would definitely need shifted higher than the graph goes (6800) since the HP is still above(~375hp) which after a shift would be 4000rpm (~275hp).

Keeping the engine in its highest HP range throughout the run will produce the quickest ET.

Rick

[tk]

Take this. Same motor, suspension, tires, just different camshafts.
4 speed auto, w/ a 3200 stall converter.

Which one of these would get you the quickest e.t.? We'll use: (green, red, blue)

I would tend to think the one with the most low end torque for quicker acceleration. Green

There are some fast times with "over-cammed" setups in the LS1 department. The intake manifold limits us to 4800rpm for peak torque. Seen on this graph the smaller cam, (green - 224 duration @ .05) even creates peak torque around this mark. It even has 4* of advance ground in, which drops the rpm band. So obviously, I'd think for a cam-only setup, they are all over-cammed. I've seen 220* @ .05 duration'd camshafts (x-er line of comps) create 400rwhp just as these did. It seems if the intake didn't limit rpm, that these sized camshafts would create peak in the 5000 rpm range.

I'm just wondering what is considered a reasonable trade off for low end torque for high end? Or in other words, is there a trade off that will give you quicker e.t.s when dealing with raw rear wheel torque. I know, the stall could be bumped, exc. but I'm more curious on the power aspect.

Kyle

Actually you would probably be surprized at the outcome

I have found that in the car the results are actually very interesting...

I'm sure Darin knows where I'm coming from.

In the car theoretically the green line will seem better but once in the car you might get a better over all result with the blue or the red depending on the gear ratio .

[Sticky Bumps]

We need to know the rear gear, trans ratios and weight to tell which would be quicker. HP at higher rpm would also help.

Automatic, 4 speed. 3.73 rear
3.06-1.63-1-0.7

The engine is significantly under-convertered for best performance. Normally an auto trans will fall back to ~stall speed after a shift. With this combo peak power is so far above the stall speed that if shifted @7000 it would fall back to 4000 with a 1.75 ratio change(700R4?). We don't know what the HP is higher up, but with this converter it would definitely need shifted higher than the graph goes (6800) since the HP is still above(~375hp) which after a shift would be 4000rpm (~275hp).

True. I picked the converter, just as a comparison measure. But, with the smaller stall-converter, the Green camshaft would fit the power band better. Seeing as the shift-extension would be lower from the small converter.

Keeping the engine in its highest HP range throughout the run will produce the quickest ET.

I think, before I started this thread, I was paying attention entirely to much to the torque curve. Once gear ratios and how long you are staying @ what rpm enters, it fills in the blanks.

Thanks,

Kyle