TheViper

i'm building a 350 with a hydrolic roller cam, 041 heads and about 9.5-10:1 compression. i've been thinking about going with the comp XE276HR or 270, or maybe a lunati. the car is going to be a daily driver but i want it to have good performance. i don't realy want to go with anything bigger than the 276 or smaller than the 270, what would be the trade off from going with one or the other? i'm leaning tward the 270 because it will give better gas milage and a flatter torque curve. what do you think? if you've had either one of these cams please let me know what you thought. thx

Chris89GTA

iTrader: (2)

I would personally go w/ a COMP XE grind cam over any Lunati cam. The Lunati cams use really lazy ramp rates compared to the XE cams. If you look at advertised duration and duration at .050 you can see what I am talking about. For instance the Comp XE 276 or (224/230 @ .050) has an advertised duration of 276/281. And a Lunati cam w/ similar advertised specs such as the 219/227 @ .050 has an advertised duration of 287/298. that is almost 10* of intake duration and 17 degrees of exhaust duration to get a smaller cam at .050. So you can see what the ramp rates do for the cams. You are actually running a "smaller cam" but getting the effects of the larger cam because the valves are opening that much faster and are open more at .050.

Which XE you go w/ will depend on what intake you are running too.

Rustydawg

I suggest that you find a comfy seat and call the Comp Cams 1-800 tech line (the hold times can be a while).

You will probably find that with the added cubes you won't need a whole lot of camshaft to make good useable power. You should be able to make gobs of torque right up through the midrange with a fairly mild cam and good cylinder heads. Check out the dyno tests of several Comp Cams on their website.

So long as you answer the Comp Cam tech's questions honestly - like the gears you are running today, not what you want to run - you should have reasonable gas mileage and be happy with the resulting torque curve from your 350.

TheViper

how much hp do you think i will get with a 350 and bigger cam? right now with my 283, 204/214 duration(a factory grind for something i think) melling cam, to a 350 with a comp 270 or 276 cam? right now its got to be at least 200hp at the wheels, probably more like 220. it will beat a GTA, i don't know what year or engine it was but it was a nice newer one. i'm hoping for about 300rwhp.

BTW, right now it has a y-pipe that flows maybe a little more than half that of a stock y, that will be fixed soon.

Chris89GTA

iTrader: (2)

How much the car puts down will also depend on your choice of heads. A buddy w/ an LT1, the 276 cam and ported heads that flow around 275 cfm on the intake side and he put down 365 rwhp running on 6 cylinders cause his opti was fried!!!

Rustydawg

Have a peek at these dyno runs on the Comp Cams page: http://www.compcams.com/Technical/DynoSheets/

These are tests of several hydraulic flat tappet and roller camshafts from mild to hot. They will give you an idea of some ballpark torque and horsepower available from a mildly built 350 - probably pretty close to what you intend to build.

Check the specifications of the test engines carefully, most of them are running a 750 cfm carb, Dart S/R heads, and I assume open headers. "Actual mileage may vary"... Remember that these are professionally assembled engines and they have been tweaked and tuned for the best dyno numbers.

Considering the compromises of the F-body exhaust system you should expect to lose a few HP and Ft-lbs from their numbers. It will give you a ballpark idea though.

Try to look at the useable torque figures from 1000 to 5000 RPM rather than the peak horespower up above 4500 RPM. Build the torque and the horsepower will follow - or something like that!

Sitting Bull

I agree with rustydawg

A really lumpy cam like a Comp 27x model will not give you a happy low end for a daily driver. The rumpity-rump gets old fast, especially when you can't keep up from light to light and your mileage goes south.

I think a Comp XE 262 or Crane PM266 would work extremely well all around on the street

TheViper

someone on here said they had the 270 and it idled like stock. i would think it would get decent milage if your not driving it crazy since the engine dosn't have to work as hard and you don't have to give it as much gas.

my uncle has a 70 camaro with a 350 and a pretty rough cam and it gets about 15mpg and he has a heavy foot. i don't know exactly what it is since it was in the car already when he got it.

it also has a 3.08 rear and a 4 speed, and a holley 750 carb. the 70 camaros are also a little heavier arn't they?

a while back someone on here said they built a pretty decent 406 and put in higher gears and got better milage than a good running stock 305.

does anyone have a sound clip of the 270HR in a 350?

TheViper

after looking at the 262H dyno #s it looks like it makes better power than the 270HR and better vacume. why are the #s so good on that cam compared to the roller cams? and what would be the benefit of going with a roller? if thats the case then i would go with the 262 and save $100+ compared to the roller.

do you think the 262 would be enough to get into the low to mid 13s with 041 heads(i think they flow about like the 462s on the dyno test at http://www.chevyhiperformance.com/te...98/index4.html
and do you think it would keep up with an lt1?

TheViper

i found the specs on my current cam, it has a RPM range of 1000-4500. heres where it is, its the first one with the 204/214 duration.
http://www.melling.com/production1.htm

i think if i go with the 268 i'l save about $300 at least on the cam and head work. it should be close to 300rwhp with the 041s and about 9.5:1 compression.

Rustydawg

Edelbrock posts dyno results of a 350 using a camshaft virtually identical to your Melling stick, making 310 HP and just under 380 Ft-lbs torque, see it at:

http://www.edelbrock.com/automotive/2102agraph.html

They are using the aluminum Performer heads (fairly conservative), 600 cfm on a Performer intake and only 8.5:1 compression.

TheViper

if i go with the 268H and the other stuff i have do you think its enough to beat an LT1 camaro if i have a 3.23 rear and 700 trans? thats what i'm trying to shoot for with this engine. about 350FWHP would probably do it right?

Tibo

iTrader: (15)

Viper,
What will the fuel be delivered with? That will help the most in selection. I see the Lobe Center Angle is at 110. That tighter angle will not produce as broad a curve as 112 or the stock 114. The LCA at 110 will reduce your low speed power and vaccum at your manifold during idle and cruising. We put a camshaft with an LCA of 108 in a Cavalier and another in a Beretta and the computer kept thinking there was a problem because of the poor vaccum and idle characteristics. We took a 350 86 Monte Carlo and used a 108 in it with increased leak down lifters and the computer was happy. Granted you don't have either of those, just a story. If you go tpi, tbi, or efi, and you go with 110, get a lifter with an increased leakdown rate. this will help to compensate for the added valve overlap. Also remember that with that short duration and high valve lift you will have valve acceleration that will place increased stress on your cam lobes and guideplates. Go with a slightly lower lift and a 1.6 ratio arm. Those dynos really are an impressive and good selling point for them, but remember their biggest concern is selling you one.

Chris89GTA

iTrader: (2)

You don't have to get that cam on a 110 LSA. You can get it on a 112 and a 114 as well. Its whatever you choose to do. For a daily driver I would do that 112 or the 114.

Tibo

iTrader: (15)

Also what stall converter will you use if that power band starts at what looks to be 2,250? After saying all that I know people will say they have done blah and gotten blah results and he is wrong about blah and he is a blah-head. But those are MY opinons and MY personal first hand experiences. So remember that when you are replying to what I just said. BLAH

Chris89GTA

iTrader: (2)

Edited... to keep this post on topic.

TheViper

the carb is a 600 cfm edelbrock, so there is no computer.

a while back the 262 was recomended for my 283 by comp with a stock convertor. i would think that the 268 cam would have at least as much bottom as my 283 right now with a .48" longer stroke. i probably will go with a little higher stall than stock anyway though.

Tibo

iTrader: (15)

Viper,
If you go with a longer duration camshaft, then try to get some other components that will help out with low end torque. That heavy car with an auto will accelerate faster with ten extra hp at 2500 rpm rather than 5500rpm. Driving daily with lots of start and stops will mean you'll need to have some low end torque, because that's what you drive with on the street. Whatever you go with, you'll probably find a way to make it work. Good luck.