OK, i'm not sure if this has to do with my Heads/cam or not but about 3 months after getting it installed i'm noticing something what i believe to be not normal....

When i get on the gas pretty hard i actually feel alittle "boost" or extra power when i hit approx 4k rpms. It feels like a tiny shot of NOS, nothing major but enough for me to notice the difference in power.

Any ideas? Do you need to know more info about my set up to determine a possible problem?

Thanks in advance!

Frank

 

Can you post the dyno graph for us all to see. Maybe you spike up at 4000 rpm. Not sure what else to think.

:cheers:
Matt

 

Good idea, I have shorty headers and from what i hear they are a waste with a H/C package. I'm going to get a set of TPIS and then go back to MMS for a reprogram and hopefully that will take care of that.

 

On my first HC package a few years ago when leaving the shop for the first time it noticed the same thing. Car would really pick up @ 3,800 rpm and just want to pull all way to redline. More then likely its probaly just how aggresive your cam is....What are the exact specs? If its real aggressive then it should feel exactly like what you are experiencing! :cheers:

 

My car did this when I replaced my gears and converter. I noticed when ever I punched it from 60mph through the shift point it would shift and then a surge would follow. My tranny was slipping bad so I had it upgraded and the surge was gone. :thumbs:

 

That’s what’s known as “coming up on the cam”. There is no ideal duration or lift that works perfectly at all RPM’s. Therefore cam design is a compromise that is tailored to the desired characteristics. Stock camshafts are designed for good idle, a broad powerband, reasonable power and, of course, emissions. In order to get more power, you have to give up one or more characteristics to some extent.

The way your camshaft is designed, it sacrifices some low-end power in exchange for more power at a higher RPM. The increased duration supplies the increased airflow needed at higher RPM, however it is less effective at lower RPM because of reduced compression pressure from the valves being open longer and reduced air velocity because the engine is not capable of sustaining optimum air flow at the lower RPM due to the design of the cam. The stage II heads play a role as well as they are designed to flow more at high RPM at the expense of some port velocity loss at lower RPM.

It is apparent from what you’ve said that at about 4000 RPM that the H/C starts functioning in a way that starts producing significantly more power. That is entirely normal for the H/C package that you have. With my H/C, I have the same effect but at about 3500 RPM because my cam is less aggressive.

It’s not abnormal; it’s just what I call personality ;)

 

Gotta love it!!

 

THANKS GUYS!!!! I will now enjoy the feeling instead of thinking something might be wrong. :cheers:

 

:iagree: You are just probably getting into your powerband when you feel that. A dyno graph should show that as well.

 

Here's a quote from my past report on my head-cam-tune:

"On the graphs, it matchs my power curve almost identically till 3300, and than the graph jumps 40 RWHP by 4000 and keeps on screaming till it levels flat 417 at 6100 through 6400 (Limiter is set for 6600).

"Torque does the same thing but also jumps 40 lbs between 3300 and 4000, and never dips below 350+lbs between 3600 and 6200!

All of this power feels almost perfectly seemless, and the HP and TQ climb (even the big 3300-4000 jump is gradual on the chart, and smooth on the street) so quickly & smoothly..."

It is a big bump, but the H/C & tuning makes it less abrupt-so it is less like a spike and more lie a fat speed bump!

BFL, it is normal, and some tuning might smooth it out-and give you more power!!