[Cliff R]

Here's my 02 cents, again. Small cams on 110LSA's have proven themselves to me to NOT be the best direction to go, IF you want to make the most power from your medium compression ratio 455 engine.

The XE274 cam would be OK in a "low" compression 455 engine, but it will give up some upper mid-range and top end power compared to a longer duration cam on a wider LSA.

If you want your "low" compression 455 engine to idle well, and pull hard in the lower rpm's, it's an alternative for you, but there are a LOT better choices out there these days.

At 9.5 to 1 static compression, 455-472cid, no problem at all managing more camshaft than 274 degrees. I like to see 290 to about 310 degree camshafts in those applications, and prefer to sqeeze the engines just a bit more as well. The result(s) will be better everyplace than the XE274 grind.

Here are some numbers, very respectable sent to us by a customer we set up a carburetor for. 230cfm 6X-4 heads, ported iron intake, 463cid, 10 to 1 CR, 4 tube headers, XE274 camshaft. Peak HP 414 @ 4900rpm's, peak torque 587ft lbs at 3400rpm's. Looks pretty good at a glance....right?

Same set-up using the Crower 60919 camshaft, 455.4 hp @ 5600rpm's, 540 tq at 3800rpm's. This was my own engine dyno'd for the HPP head swap article when we went to the KRE heads. After installing the KRE heads, HP jumped to 494.

Here's the trump card folks, the XE274 cammed engine was clear down to 412ft lbs torque at 4900rpm's. My engine was still making over 500ft lbs torque at 5000rpm's! It also made more average torque, and HP across the rpm range, by a considerable amount.

The tight LSA grind, short seat timing, less overlap, etc, pulled the power down lower in the rpm range, and it made less power. This would NOT show up in a "seat of the pants" assessment, but will show up on an engine/chassis dyno, and at the track. Matter of fact, pulling all the power down to lower rpm's usually fools the driver of the car into thinking his engine is making MORE power. The small/tight LSA grinds are brutal down low, spins tires easily, very responsive off idle, etc.

IF this is what you want, and how you evaluate the performance of your street car, it makes the XE274 cam a fine choice for your medium compression ratio 455.

IF you want to make quite a bit more power, and spread the power out some, with a strong upper mid-range and top end charge, install a larger camshaft on a wider LSA.

There are also other benefits from going to a larger cam on a wider LSA. If you go back up to the dyno results, notice that the XE274 cammed 455 made a very high peak torque number at a relatively "low" rpm. My own engine made about 30 ft lbs less across that rpm range, but kept the torque production over 500ft lbs clear out past 5000rpm's.

What this means is that the XE274 camshaft produced quite a bit MORE cylinder pressure at peak torque, and concentrated MORE cylinder pressure in a narrower rpm range. This is, and can be a recipe for detonation with currently available pump fuel(s).

My engine lived at 10 to 1 SCR for many years, and hundreds of track runs, managing low octane fuel without the first hint of detonation anyplace. It would easily run on 87 octane fuel, we ran it continuously on 89 octane, and when torn down for inspection after years of street/strip use, showed no indications anyplace of detonation, the bearings looked like you just installed them.

Our current engine is 11 to 1 compression, and manages 89 octane fuel without any issues anyplace. Yet there isn't a week goes by that we don't see someone throw a thread up talking about the perverbial "brick wall" of 9.5 to 1 SCR on pump fuel. This immediately leads to folks jumping all over the topic with great information about lowering the SCR, then making up the lost power with a smaller/tighter LSA, "modern" camshaft to bring all the power back.

Consider this, IF this were true, and ALL the power did come back, then the cylinder pressure at every rpm would be exactly the same as the engine running MORE compression and MORE camshaft.

Reality check. The "modern" lobe profiles do NOT bring back all the power.

They do NOT make more power over the same rpm range as the larger cam having more overlap, and more off seat timing, wider LSA, etc.

The do produce more vacuum at idle, and pull the power curve into a lower rpm range, and narrow up the power curve considerably.

The result is very good "felt" power by the operator of the vehicle.

Go to the dyno and you will find that the power production at high rpm's is off considerably. No magic tricks here folks, smaller cams on tigher LSA's make less top end power, all else being equal.. ....Cliff