skyavonee

I know a turbo or twin-screw/roots type blower will radically change the torque curve but I'd rather not go that route. I remember reading elsewhere that 4-2-1 headers are good for torque, but all the C5 headers I've come across so far are 4-1. Is a cam the best option?

Peak power is great and all, but after driving my brother's Viper GTS I've gotta say that low-end torque is where it's at!

zeevette

The right cam will increase your TQ all across the rev band, but if "low end" is what you want, maybe taller gears is a better mod? I'd do headers before a cam, but that's just me. I recommend LG Pros, or Street headers, depending on your budget. They have longer primaries than most of the major Corvette headers, and have a great TQ band, due to their design. I don't like their SuperPros, but the question of the country of origin is an internet rumor.

skyavonee

Shifting the entire curve up is definitely OK; I've just noticed that certain mods (like intake and headers) tend to give the biggest gains at high rpm and not so much below, say, 3500. Don't get me wrong - I'll still be doing intake and headers - I'm just thinking ahead a couple months about other mods that will flatten out the torque curve.

Gears are something I hadn't thought about; I assume you mean tranny gears? I would probably just get a rear end with a different ratio though before tinkering with the individual gears.

zeevette

Sorry, "taller gears'' is an old slang saying meaning rear end gears. Younger guys may not have ever heard this saying, I guess. I meant changing from the stock 3.42s to 4.10s, or 3.90s. For the instant gratification, they can't be beat, but ultimately, won't get you any more power. I had a Cobra Mustang ('01 NA) before my Z, and I got 4.10s, and didn't like them. At least on that car, first gear went by too quickly, but the Corvette guys swear by them. They are not the way to go if you plan on a SC or turbo setup later, though. Personally, the low-end TQ is good as is, but after driving a Viper, must seem weak. You can see by my sig. that I've been through quite a bit of modding over the almost 8 years of ownership, so I know the allure of "more". GL.

sami85L98

Get TVS/magna charger and it will feel like you driving a 427 Cid or more, or drop a real 427 or 402. If budghet is concern than gears (numerically higher 4.10). You have three options if you want low end torque, no cam small or big will give you great low end punch period.

ctusser

Trying to reproduce the low end power feel of a 500 ci motor is a tall order for an NA 346, and to actually "feel" significant low end increases will not be cheap and will still probably leave you wanting for more. Your best bet would be to increase the cubes through stroking or a shortblock replacement matched with a modest cam, good flowing small runner volume heads and running the highest compression you can with your available fuel grade.

LT1driver

4.10s better suited for the coupe trans, z 1st is to steep for 4.10s, 390s better choice just like back in the day for those of us who were there

Nexus9

I have to say, this is the weirdest thing. I have the exact same question, and nobody seems to have an answer.

I just bought a "436 horsepower" Grand Sport that "feels" more slack than my previous 2004 C5, which supposedly made 100 less horsepower. The problem, of course, is that everybody is so enamoured with the word "horsepower" that the manufacturers are building cars that simply have higher and higher numbers - knowing that that will attract the attention of potential buyers. But Horsepower is simply a function of BMEP x rpm - so to get more horsepower, the engines are being built and tuned for higher rpm peak power, which, of course, makes them actually feel weaker at part throttle openings in lower rpm - which is where we all spend 90% (or more) of our time driving. (okay, you wanna little cheese with that whine...?)

I just spent last winter building a Harley motor, and in THAT world, there's a lot of information from cam manufacturers about where we are shifting the torque curve to - sometimes higher, sometimes lower. Dyno charts are available on the manufacturer websites along with descriptions of how the cam will affect the power delivery in a given motor. There's a LOT more talk about intake valve closing, which determines cold cranking pressure (what we actually read with a compression guage), which in a lot of ways determines low end torque; and a lot more awareness of shaping the powerband with the cam.

I've just spent hours searching the web for LS3 cams, and all I seem to be able to come up with regarding cam profiles is a series of numbers (duration and lift, lobe separation angle) and a bunch of sales rhetoric (increases power everywhere! ...blah, blah, blah...). Questions like the one posed in this thread go unanswered, or are turned into a gear ratio discussion.

So - I'm dragging this up again (a year later) just in case there's any new information out there - I guess I'm part of that small minority that's perfectly happy with 400 hp at 5500 rpm, but would like to add 50 ft/lbs at 3,000, in a car that makes about as much noise as a stocker. To that end, I've already bought a K&N FIPK and LG Motorsports Long Tube Street Headers (stock mufflers) - IS there such a thing as a cam that will lift up the low end, even if it doesn't add to the magical "horsepower" number?

Thanks for your input! Jon

skyavonee

I haven't talked to my tuner yet, but based on my research, right now I'm looking at a package that includes these components:

218/224 605/609 112+5 cam - The low duration, high lift combo is good for low-rpm torque.

AFR 210 heads - same intake runner volume as our stock 243 heads but with significantly better flow. Greater port velocity = more torque.

have heads milled to bump compression ratio up to 11.0 or higher - This increases engine efficiency and thus increases torque everywhere.

Underdrive pulley and light flywheel - Reducing parasitic rotational losses gives better throttle response and increases torque everywhere.


Check out these cams: Comp's LSr Series
Be sure to click the "Camshaft Specs" link on each camshaft page.

WannaC5Z

I drove a buddy's '02 Z06 with an aftermarket cam this summer at a road course and it felt like a beast compared to my '97 Slobra. I remember how much better my Cobra felt after going from stock 3.27's to 3.73's. Doesn't add any horses but it definately gets you down the track faster. I'm surprised you didn't like the 4.10's on your old '01 Cobra. Everyone I know says 4.10's are the way to go with n/a'd Cobras. I am shopping for a Z06 because it is going to cost too much to get close to 400hp out of the Cobra when I can just buy a Z with it stock, plus handle better in the corners. I shouldn't be surprised when I read someone wants more torque out of Z, when they are already great torque monsters...at least compared to n/a'd 96-01 Cobras. It is all a matter of perspective and what you are driving at that time. To me right now a bone stock Z is the answer, but I am sure the mod bug will hit me again when I buy one. I have over $10k in my snake on top of what I paid for it 7 1/2 years ago. That is why I am going to keep it and just add another toy to the garage.

Paul 75 L82

LS motors just love cams, call Texas Speed and see what they have to say.

MawneeC5

You have exactly the same goals I did this time around with my Z06. More bottom end grunt. I went from a 98 procharged vette to an Rx8. Even after fitting a turbo that car was gutless down low. When I got back into a Vette I knew exactly what I had missed

It sounds like you are on the right track to get what you want out of the car. Just so you know, Belanger makes a 4-2-1 header. I'm running them and they perform and sound great

http://www.westcoastcorvette.com/p-2...8-2000-c5.aspx

Nexus9

Thanks, guys. Sky, I had a couple of thoughts about your response. First, thanks for chiming in almost a year later - I'm sure you've had a lot of time to research this. The lift and duration are concurrent with what I learned on the 103 project (Harley) - shorter duration and higher lift can be a good combination for more low end. Do you have a brand or model for that cam profile?

The one other thing I wanted to mention that I don't hear a lot about on the 'Vette forums is that compression ratio is not cold cranking pressure. You can have a motor with 10:1 compression ratio (which simply means that the volume in the cylinder is ten times as great at BDC as it is at TDC) that produces 195 psi of cold cranking pressure (what we measure and call "compression") - or a motor with 11:1 cr that creates 175 psi ccp. Cold cranking pressure, in a large way, affects BMEP (brake mean effective pressure), so is an important number (BMEP x rpm = horsepower). Any given ccp in a 4-stroke engine is a relationship between compression ratio and intake valve closing - (aaahhh, there's the point!) - so before you go shaving your heads, find out what the IVC is for the cam you have chosen - in other words, you can adjust ccp with IVC or, in more visual terms, the piston doesn't start compressing anything until that intake valve closes After Bottom Dead Center, and the later it closes, the less ccp you will have (and vice-versa). I'm gonna assume that that's where the "+5" is coming in on those cam specs - you've got an adjustable drive sprocket, and your tuner is suggesting that you install the cam advanced 5 degrees, which will close the intake valve earlier for more compression. In a liquid cooled motor, with computerized spark management, I would think you and I want a ccp around 190. (?) If I've got my numbers right:

Bore: 4.067
Stroke: 3.622
Head Gasket: .040
Combustion Chamber Volume: 73cc
Static Compression: 10.43:1

Then an intake valve closing of 48* ABDC should give us

Corrected Compression: 9.19:1 and
Cold Cranking Pressure of 190.2 psi.

Which, in the air-cooled motorcycle world, was a safe place to be on 93 octane pump gas. Does anybody know how high we can safely go in an LS3 motor on pump gas? (depends on cooling/swirl/spark management)

In any case, what all this is about is: Earlier IVC = more low end.

Jeez, I guess I shoulda just said that in the first place and then shut the heck up.

Jon

Nexus9

Oh yeah, one more thing. I keep hearing about the underdrive pulley, but I've read some comments by guys who installed one and regretted it. Any real-world experience with that? Did it make enough of a difference to be worth while?

Thanks, Jon

skyavonee

It's a custom grind of Comp's XFI lobe available through Texas Speed.

This gives me something more to look into.

Remember you're posting in the C5 Z06 forum (we all have LS6's!). Better off asking around the C6 forums for feedback on this stuff.

Based on my research, the number of satisfied customers seems to dwarf the unsatisfied ones, at least in the C5 Z06 world. UDP's are typically installed along with a cam, so my guess is the unsatisfied customers might have ended up going with too large a cam and/or didn't get a great tune afterward. That' just a guess though; could be completely unrelated.

Nexus9

Right - o. This thread originally came up in a google search, and I didn't pay much attention to where I was on the forums. Thanks.

cv67

You will never get 50lbs tq at 3k with a cam change.


You need cubic inches my friend (lots of em)wether you stroke the motor or add a SC . It will never feel like the Viper with 346

AU N EGL

California is the biggest problem

the mods needed for more low end torque are not legal in CALF

LG Pro LTS with X pipe and Straight pipes

and a torque cam

But really just swap in an LS7

danziger

100shot of nitrous would do it...cheap and effective!

skyavonee

Moderators please lock this thread. It was brought back from the dead 13 months later by Nexus9, and his questions have since been answered.