I recently put in an lt4 hot cam and after getting used to the power i have enough courage to bring it up to red line, but at about 5000 rpm it doesnt sound the same and seems to run out of steam (or just doesnt keep pulling hard like up until then). i thought this cam was supposed to run well over 6? any thoughts?

 

Did you also change the valve springs?

Jake

West Point ROCKS!

 

My hot cam car hits the rev limiter (6150 rpm) in first gear fast. I usually leave the shifter in 2nd and let it shift itself at 5800.

 

I have a manual, and I put In 1.6 rr and lt4 springs.

 

Have you checked your throttle cable lately?

 

Don't confuse two things: The ability of an engine to rev to a certain RPM is one thing, but to still make good power up there is yet another.

Once an engine passes its RPM of maximum power, the power drops off and you can feel it since the engine no longer pulls as hard.

If your engine has reached it's power peak at 5000, then power flattens out or drops, it could be caused by a number of things. Something as simple as the heads and or intake maxing out in airflow, exhaust unable to flow enough, fuel flow, on and on.

Are you getting any error code(s)?

Jake

 

Did you get it tuned after installing the cam? I'm not sure what exact characteristics it would exhibit if you didn't, but I do know that you leave about 30% of the power gain of the Hot Cam on the table without a good tune.

 

I do have stock heads and intake. And haven't adjusted the throttle cable at all.

I ordered a canned tune from PCM for less and installed that right away.

So it sounds like it's restricted flow from the heads then yeah?

 

Many guys confuse an engine's RPM capability with the power it can make.

Many engines can rev to redline and higher, but the question is "Is it still making good power up there?"

If you look at any of the dyno graphs found in mag articles and on the internet, you'll see that an engine can continue to rev higher and higher, but the power drops off, sometimes like it's fallen off a table.

Engine keeps revving, but doesn't pull as hard.

The main thing about engines is that in making more power, it becomes an exercise in removing corks to airflow. Once you remove one cork, another one presents itself.

So, when you install a cam that allows more flow, the heads, intake manifold or exhaust can become the next cork, which will limit power. So, you attack the, let's say, the heads; now the intake flow restriction rears its ugly head; then the exhaust, on and on.

It becomes an exercise in cork removal.

If you bolt your car to a chassis dyno, you'll be able to see on a graph just where your power drop off happens and, in many cases, the dyno operator can tell you what needs to be done to correct it.

It could be caused by a number of different things, like fuel flow, knock retard, valve float, etc.

I wish I had a crystal ball and could tell you exactly what's causing your concern, but, alas, . . . .

Sorry I couldn't help more.

Jake

West Point ROCKS!