Comp Cam Stage 2 VSR question

[Gruca]

So I'm debating on the Comp Cam 127300 but they recommend a 3.90 gear. I have a 3.73 already in the car, is that going to make that big of a difference that I should choose a different cam?

 

[702GT]

The biggest reason I've found in gear recommendation is compensating for low rpm powerband shift and the gear helps for streetability (less bucking). However, most tuners are sharp enough to compensate for taller gears with cams. If you like 3.73's then keep them. Everyone told me to run 4.10 or 4.30 gears when I picked a centri for my power adder, but the way I drive and the conditions I drive in, 3.73's are spot on perfect. I ran 4.10's with the comp 127020 cams, it really does help get into the powerband faster, but there's alot more shifting and if you like to cruise around 80mph you better love your exhaust tone around 2800rpm lol.

 

[2005Redfire6]

The biggest reason I've found in gear recommendation is compensating for low rpm powerband shift and the gear helps for streetability (less bucking). However, most tuners are sharp enough to compensate for taller gears with cams. If you like 3.73's then keep them. Everyone told me to run 4.10 or 4.30 gears when I picked a centri for my power adder, but the way I drive and the conditions I drive in, 3.73's are spot on perfect. I ran 4.10's with the comp 127020 cams, it really does help get into the powerband faster, but there's alot more shifting and if you like to cruise around 80mph you better love your exhaust tone around 2800rpm lol.

+1

OP, also take into account your rear tire size which effects the rear gear.

 

[Gruca]

Thanks for the info. My rear tires are 255/45/19. The 3.73s are good enough for me as they sit at 2500 rpms around 80mph. With muffler deletes, its plenty loud already. So I'll add a cam and LTs to make it worse

 

[eighty6gt]

I did a ton of research on the 300's and 350's. Nobody says they lost any bottom end.

 

[MassMustang]

I now have CompCam 127350's along with 4.56 gears, 5-speed and taller rear tires (28.4" - 295/45/18). The taller tires drop my effective gear ratio to ~4.30. I like the aggressive gears, but that's just me.

The before and after? It's not super choppy with excessive lope like the 127500's or Mutha Thumprs I've heard, but I set my idle to 675 rpms and I think it sounds good with a little lope at idle. Very aggressive and noticeable. Factor in Kooks LTs, hi-flow cats and Pypebombs for the exhaust note.

My thoughts?
If your rear tires are taller than 27.1 (stock height) then the effective gear will drop a bit. So go with shorter gears (3.90/4.10)

If they're stock height, then 3.73's don't seem too bad. Try 'em out.

Either way, you can always add gears later. Plus, if you're thinking a blower, depending on what you wanna do there, you may time to think about the best gears for your normal driving habits. Daily Driver vs 1/4 Beast

Me? My two remaining goals are a centri blower (Novi 2200) and a stroker engine (5.0-5.3L)

Hope that helps!!!

 

[702GT]

I did a ton of research on the 300's and 350's. Nobody says they lost any bottom end.

It's a powerband shift, not a loss, is what I meant. Whatever torque you make at 2,000rpm will not be there the more aggressive cam you run, it will shift higher in the rpm range. You should always make additional power with a NA cam, but the vast majority of NA cams will shift that power higher in the powerband. So if you made 200ft/lbs at 2,000rpm with stock cams and 300ft/lbs max torque at 3,500rpm, for example, and swap to a 127020 comp grind, it's possible you'll only make 150 ft/lbs at 2,000rpm and your new max of 320ft/lbs of torque at 4,500rpm.

Now you have this low-end void in the lower powerband that wasn't there with the stock cams. The engine used to have enough grunt to push those 3.55's or whatever economical gear the car came with factory. Now the engine has to be reved higher to achieve that same grunt to get the 3.55's turning. Instead of making the engine load up, you give it more torque advantage by using 3.90's+. Now the car responds like it did, or better, with 3.55's in that idle to 3,000rpm powerband.

I know you understand all this, I'm just making an elaborate point for the OP.