Cambered Rear Vs. Weight Reduction Vs. Power Mods - Help Me Decide!

[TMSBOSS]

Also consider another difference in drag racing to road racing. Auto trans/torque converter in drag racing and a standard clutch/trans in road racing. The torque converter in a drag car will help keep a drag car in the sweet spot, higher RPM. Power below the curve is not as significant in drag racing because a drag car spends less time below the curve thanks to the torque converter. With the standard trans/clutch there is no torque multiplication and we spend more time at lower RPMs pulling from the corners.
I found this discussion on torque multiplication. https://engineering.stackexchange.com/questions/12184/torque-converter-torque-multiplication

 

[Don Lariviere]

Yes you are correct, I should have put more information in my post. I have the Hot Rod cams in my 3V, and relevant total power to me is 3500 to redline. Beyond the Hot Rod and the Mutha Thumper type cams you are going to start hurting the lower portion of that band without significant modifications to the engine. I also didn't go and look to see what cam you were running.

 

[SMGDHG]

Not being a pro engine builder myself, but very experienced in the art of race craft let me add some thought to this:
The broadest power band possible will likely give the best lap times. Any time spent under the curve will cost you. If you put in a cam that has less power at lower RPM and you have to use that rpm you will now spend even MORE time in that soggy spot than you have been, so don't disregard that fact. Drag racing all you have to worry about is RPM drop at the shift, and its all WOT in a car with momentum, so as long as you can stay in the sweet spot you are golden. Unfortunately with road racing you have to pull out of corners, sometimes well below the curve and the more you add to the top end the more that low end will suffer and that hurts lap times because you will now be spending even more time under the curve. That high rpm peak power is only as good as much as you can use it, and that depends a lot on the weight of the car, the gear and the track.

Example:
A 7 speed sequential can stay within a nice short power band so you are always in the sweet spot, you can get away with a peaky cam with a high HP number. That's why the closer ratio transmissions work so well.
I gave away a lot of peak HP with the super mild cams in my coyote, but I pull EVERYONE out of the corners and once I am ahead you are going to have your hands full catching me.
I've told this story before so if you've heard it already I apologize, but I think it applies here.
At nationals I met the guy with the Kenny Brown Boss 302 AIX car. He told me "I have been asking around about you, including other builders and all 6 of them told me the same thing:
"Sal is very good at beating cars with more HP than he has". I then yarded him coming out of turn 11 and by the time his car got on the pipe I was long gone. Unfortunately he lost his power steering pump later in the day and was done for the weekend so he didn't make the feature. I attribute that to the low end/mid strong cams that I have. Its kind of like turbo lag....I don't care how much HP you're making as long as I'm in front of you. I've had this experience for decades in circle track as well...I don't care if you catch me at the end of the straight because we are going to have to slow down and get on the gas again and I'm going to be gone while you're still waiting for V-Tech to kick in. LOL.
A side benefit is that smaller cams need less valve spring which saves heat and increases reliability. Broken cars rarely win.
Also, many bigger cams limit or lock out the variable cam timing which is a super great feature of these motors.

Moral of the story....be careful chasing big peak numbers, in the end its what's fastest over all that wins races.
That being said, my suggestion is ask Shaun at AED for a cam recommendation and believe whatever he tells you.

I definitely hear you in regards to wanting to avoid a "peaky" power curve. The silly turbo roll race cars always make me laugh; they slowly accelate up to like 5k rpm and then just smoke the tires when the turbo(s) kick in. Fun to watch but doesn't seem effective for what we do

I actually had a pretty nice talk with Shaun in regards to cams a couple months ago (I wanted to have him make me some) and he said similar things to what you and Don state; going too big on the cam (ie, "peaky") would end up hurting more than helping. Which is why he recommended I get a custom grind from L&M or stick to one of the off the shelf, mild NSR cams. Like the FRPP hot rods that Don has.

My one question to you all is; isn't it our civic duty as a driver to do our best to keep the engine in it's powerband at all times? Maybe I have just gotten lucky with my current vehicle configuration and the tracks I run, but I can usually find a way to keep my car in this RPM "sweet spot". My Laguna example above for example, where I only spent 21% of the time out of the sweet spot of the engine. I would argue that if you are spending a much higher % of time than that out of your power curve, you need to downshift, go faster or change the gearing in your car (ie go to 4:10's).

Yes you are correct, I should have put more information in my post. I have the Hot Rod cams in my 3V, and relevant total power to me is 3500 to redline. Beyond the Hot Rod and the Mutha Thumper type cams you are going to start hurting the lower portion of that band without significant modifications to the engine. I also didn't go and look to see what cam you were running.

Those cams have been at the top of my list! How have you liked them? Any lap time data before/after? From what I have gathered you are absolutely right, it's important to not hurt the low end too much and most of the bigger cams do for the poor little 3v. But those hot rods keep the stock phasers and seem to be pretty mid range friendly.

 

[Fabman]

I definitely hear you in regards to wanting to avoid a "peaky" power curve. The silly turbo roll race cars always make me laugh; they slowly accelate up to like 5k rpm and then just smoke the tires when the turbo(s) kick in. Fun to watch but doesn't seem effective for what we do

I actually had a pretty nice talk with Shaun in regards to cams a couple months ago (I wanted to have him make me some) and he said similar things to what you and Don state; going too big on the cam (ie, "peaky") would end up hurting more than helping. Which is why he recommended I get a custom grind from L&M or stick to one of the off the shelf, mild NSR cams. Like the FRPP hot rods that Don has.

My one question to you all is; isn't it our civic duty as a driver to do our best to keep the engine in it's powerband at all times? Maybe I have just gotten lucky with my current vehicle configuration and the tracks I run, but I can usually find a way to keep my car in this RPM "sweet spot". My Laguna example above for example, where I only spent 21% of the time out of the sweet spot of the engine. I would argue that if you are spending a much higher % of time than that out of your power curve, you need to downshift, go faster or change the gearing in your car (ie go to 4:10's).

Those cams have been at the top of my list! How have you liked them? Any lap time data before/after? From what I have gathered you are absolutely right, it's important to not hurt the low end too much and most of the bigger cams do for the poor little 3v. But those hot rods keep the stock phasers and seem to be pretty mid range friendly.

Yes, that's why I put the caveat "If you need to run at that RPM" and "depends on the weight, gearing and track". Just giving you general data.
I try to keep my shifting to a minimum....for me its way faster to just let the motor grunt and pull all the way to redline without shifting. Ever drag race an automatic car with the same power? Its neck a neck until you shift....then you loose a little ground and then you shift again and loose a little more until you are looking at his back bumper.
This is also why I wind everything to the moon, while it may not be making good power up that high, if it eliminates a shift its a net gain.
I try to gear my car for the tracks I run and fortunately Sonoma/laguna/T-hill all have similar gearing needs so my 1:30 3rd gear Magnum XL and 4:10 diff is perfect for me....I come out of all the critical corners in 3rd and it's just about tapped out where I need to shut off. So I may pull from 3500 to 8200 or more....this is the beauty of the Coyote, lots of RPM.

 

[Dave_W]

This is also why I wind everything to the moon, while it may not be making good power up that high, if it eliminates a shift its a net gain.

It actually eliminates two shifts, as you'll have to downshift as well. Add in the possibility of blowing the downshift, or not getting a perfect rev match and upsetting the car under braking / turning, and it's an even bigger challenge.

In autocross, I'll happily bounce off the rev limiter a few times rather than upshift and have to downshift right away.

 

[Fabman]

It actually eliminates two shifts, as you'll have to downshift as well. Add in the possibility of blowing the downshift, or not getting a perfect rev match and upsetting the car under braking / turning, and it's an even bigger challenge.

In autocross, I'll happily bounce off the rev limiter a few times rather than upshift and have to downshift right away.

Exactly

 

[Fabman]

Example...watch the first 60 seconds here.
1) Don't shift when everybody else does. (Blue shift light is 7800 rpm - Yellow is 8200)
2) pinch the first corner so nobody can get underneath and take the corner.
3) hammer the throttle looooong before anybody else....and goodbye!

 

[SMGDHG]

Example...watch the first 60 seconds here.
1) Don't shift when everybody else does. (Blue shift light is 7800 rpm - Yellow is 8200)
2) pinch the first corner so nobody can get underneath and take the corner.
3) hammer the throttle looooong before anybody else....and goodbye!

Ok so I watched the first 60 seconds.

And then I kept watching and reached the 6 minute mark with that white BMW, was that contact?!

I'm not ready for W2W anytime soon LOL.

 

[Fabman]

Ok so I watched the first 60 seconds.

And then I kept watching and reached the 6 minute mark with that white BMW, was that contact?!

I'm not ready for W2W anytime soon LOL.

Nope, no contact....but it was close. Was about a pucker factor #12. I've run that car for years and years without a scratch and it almost ended right there.
If you ask anyone what the most important thing on a road race car is they will tell you "The Brakes"....what's the absolute worst thing on my car? The brakes.
Hoping to have that sorted for 2024.

 

[Hobdul]

This thread is a great example of why TMO is so great...hopefully at some point I'll have something helpful to contribute here as well

 

[Don Lariviere]

So I just got a used LS3, I have a 2014 body in white that has every ounce of unnecessary sheetmetal cut out of it. It's pretty floppy with no cage in it right now!! I'm going to move all the cortex parts from my Blue 2008 GT into it, so it should be a 'maximum effort' stock tub based Mustang. We'll have to see how it does at the Calif tracks, I need to find a GSR trans that isn't $10k...

I'll start a new car thread on it when I'm back in town, hopefully we'll all learn a lot!! I'm hoping to be in the high 1:40's at Buttonwillow 13CW.

Don