LT4 HOT CAM ECM QUESTIONS
Thread Starter
Intermediate
Joined: Dec 2002
Posts: 41
Likes: 0
From: Jeffersonville IN
LT4 HOT CAM ECM QUESTIONS
I am going to put a hot cam in soon but money is tight so I want to do it by steps. Put hot cam in and drive for a wile. Then program the ecm I want to do it myself so I will get a laptop and the software and program as I get the money. But what I would like to know is how the car would run without programing the ecm and do you need to replace anything like waterpump or springs if thay are in good shape. I read something that said you would get a good gain and performance with the just the cam. But even better results after the program. What do you think???
Safety Car
Joined: Jul 2001
Posts: 3,524
Likes: 1
From: Pinellas Florida Misfit
Cruise-In III Veteran
Re: LT4 HOT CAM ECM QUESTIONS (TAOS6Speed)
An LT1 is going to run pretty bad with stock programming.. LT4's handle the hot cam a bit better, but even that isn't great.
You may find the Optispark and water pump are in need of replacement... I'd certainly plan to have the budget there for it once you get it apart. You will ned to replace the springs... LT1 stock springs arent up to the task.
If you are doing the entire Hot Cam kit, it comes with springs and the roller rockers. There have been forum members who have reported 40+ rwhp with this kit along. Doing just the cam and porting the intake on my LT4 gave me 30 rwhp before i got the tuning done. No idea what I'm making for power now, but don't expect more then 5-10 HP extra with tuning, biggest gains come in drivability.
You may find the Optispark and water pump are in need of replacement... I'd certainly plan to have the budget there for it once you get it apart. You will ned to replace the springs... LT1 stock springs arent up to the task.
If you are doing the entire Hot Cam kit, it comes with springs and the roller rockers. There have been forum members who have reported 40+ rwhp with this kit along. Doing just the cam and porting the intake on my LT4 gave me 30 rwhp before i got the tuning done. No idea what I'm making for power now, but don't expect more then 5-10 HP extra with tuning, biggest gains come in drivability.
Team Owner
Joined: Sep 2001
Posts: 62,178
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: LT4 HOT CAM ECM QUESTIONS (TAOS6Speed)
You will get a gain with just the cam, but your idle is gonna be crappy, the duration is so much bigger that the computer wont be able to smooth it out without a reprogram.
Your best bet is to buy it now, and save your money til you can do everything that needs to be done. You should also put in new springs with the hotcam.
While you have the cam out, at least replace the WP.
Your best bet is to buy it now, and save your money til you can do everything that needs to be done. You should also put in new springs with the hotcam.
While you have the cam out, at least replace the WP.
Instructor
Joined: Mar 2002
Posts: 181
Likes: 0
From: Allen TX
Re: LT4 HOT CAM ECM QUESTIONS (TAOS6Speed)
For reference, I added the entire hot cam kit and gained 46 rwhp. This is on an OBD-II car. The idle is a bit rough (got a nice lope), using a scan tool it meters rich at low rpms and leans out up top. I do set an occassional misfire code (due to the HOT cam's overlap) but clear it with scan tool easily.
A friend installed the same kit on a '94 with OBD-I (like yours) and had even better results (track times). His car idled better and got better fuel mileage with no trouble codes for misfires (no crank sensor on OBD-1)
As others have said, the stock valve springs are NOT up to handling the lift of the HOT cam. These springs must be replaced. The HOT cam kit contains the cam, matched springs and roller rockers.
Since you need to pull the waterpump, you can check the bearings. My waterpump bearings had apparently begun the process of giving up the ghost, several "*****" were missing from the bearing. Overall it is cheap insurance to replace it, before it fails and takes out your OPtispark with a leak.
Programming would be a definite plus, but I think that you can get by without it. Just remember, without it the engine will be a bit "rougher".
See ya,
John
A friend installed the same kit on a '94 with OBD-I (like yours) and had even better results (track times). His car idled better and got better fuel mileage with no trouble codes for misfires (no crank sensor on OBD-1)
As others have said, the stock valve springs are NOT up to handling the lift of the HOT cam. These springs must be replaced. The HOT cam kit contains the cam, matched springs and roller rockers.
Since you need to pull the waterpump, you can check the bearings. My waterpump bearings had apparently begun the process of giving up the ghost, several "*****" were missing from the bearing. Overall it is cheap insurance to replace it, before it fails and takes out your OPtispark with a leak.
Programming would be a definite plus, but I think that you can get by without it. Just remember, without it the engine will be a bit "rougher".
See ya,
John
