Hey all

I'm getting ready to install the LT4 hot cam kit, and I'm getting a tune immediately afterwords. I'm curious, where should I be shifting (what RPM) after the install...

I need to know this in order to raise the limit on where the PCM cuts off the fuel...

Thanks!

 

If it runs right your HP peak should be around 6400rpm. Shift at 6800rpm and you'll be good.

My old LT4/Hotcam setup peaked at 6400rpm through stock manifolds and 100K cats. I have "same day and dyno" info with other nearly identical setups that verify the power peak.

 

Dont listen to him. Youll just over rev the bitch and spin a bearing.

His is a freak rather than the norm.

EVERY stock headed, cam only LT1 I have EVER seen, in person, and on this board, made peak power at about 6,000RPM's This is where the stock heads choke them out. With the hot cam kit, you dont need to shift any higher than 6200-6300 RPM's.

Jesus Christ, the stock PCM wont even allow the engine to go past 7,000 RPM's and nearly every other cam on the market makes power well past the range that the hot cam does. Even guys with the CC306's LE1, & LE2's are shifting before that. As a matter of fact, I am pretty sure, even a LE3 HEAD AND CAM LT1 makes peak power at 6500-6600 and is shifted around 6800 on a 350. Lower though on a 383.

 

Here's a question: Do you want peak power in the current gear, or do you want peak torque in the next gear?

When you shift, what will your RPM be at? Is that where you want the engine power to be at for the next gear, or would it benefit a little more by holding the RPM a little longer, or shifting sooner and taking advantage of the torque at the lower RPM with a taller gear?

The Hotcam is real happy between 5300 and 6300. Above that, it starts wheezing and you are probably wasting time in that gear. Your peak torque RPM is probably at about 4200-4700.

 

my hotcam does not wheez out untill 6,800

 

Ultimately to get the caar from point a to point B fastest your going to shift 3-500 rpm after the peak in your powerband. This puts you closer to your peak in your next gear when you shift, and you should still make more past your peak then after you shift into the next gear. On a stock motor however, other considerations like wear/tear and stability of the stock rotating assembly come into play. I wouldnt rev a stock bottom end past 6500, and even that high only if its been WELL taken care of since day one. Ultimately its your decision. You WILL go faster shifting higher, but rpms break stuff, its just the nature of the beast.

 

Ion (MadZ28.com) tuned mine to shift at 6100 RPM. Shifts great.

 

my hot cam runs dead around 6900... i like to shift between 6600-6800.. I have stock bottom end thats seen plenty of 7k rpm pulls and now has 50k miles on it.. if a motor is built right it will be ok. However i would pull it to hard because the opti wont hold...

 

6500 is a good compromise, you're drag racing anyway so it's not like it sits at that RPM

 

I bet if you guys who are winding your hot cammed cars out to nearly 7,000RPMS shifted sooner, you'd turn better times ...

Ask any one who builds LT1's ... A stock headed car is not going to make dick past 6000RPM's, so spin it a little past that, and then shift. At like 6300ish?

 

Thats because he knows the hes doin. Shifting an LT1 with stock heads over 6200 is a waste of RPM's. Anyone who has ever seen dyno graphs of LT1's see that after 62 the HP falls super fast.

Dont waste your RPM's man. 6100 sounds good.

 

I agree 110%.

 

He has an LT1 not an LS1.

 

^And if its in his LT1 car, it has a blower and nitrous. Having a power adder makes it easier to get the revs out of a smaller cam.

 

LT4 Hot Cam Shift points.

When it starts going pop de pop pow bang ----- SHIFT