|
|
Item Posts
Sort Order
|
|
|
Power lacking
|
LoudNF
New User
| Posts: 2
| Joined: 11/08
Posted: 11/27/08
07:05 PM
|
|
Hi,
I'm new to this forum and need some ideas on what might be causing a lack of power from my engine.
I have a 97 GMC Yukon with the 5.7L SFI. Now, this engine is far from stock. It has been completely rebuilt top to bottom. Bored out, heads polished, everything. The heads are stock, as is the bottom end(though new). I put in a comp cams xtreme 4X4 cam with a 474 lift and 210-214 duration. new lifters, 1.6 ratio roller rockers. free flow flowmaster exhaust, K&N intake. the tranny is a 4L60E that has been rebuilt. i have no low end torque off the line and power doesn't really kick in till 2500 to 3000 RPM.
i've thought the computer might be a bit of a problem, as the program is stock, and i have just recently thought maybe the stall speed might be wrong for the cam.
If anyone has some ideas that would be a great help.
Thanks
|
|
|
|
|
Posted: 12/01/08
08:22 AM
|
|
It sounds to me like you've answered your own questions. Have you performed any computer mods? You need to. Also a stall wouldn't hurt, just something a bit over stock, 1200-1400ish would probably be in the neighborhood. What valve springs are you running? The cam you have has fairly aggressive lobe profiles and stock springs wont like them too much.
|
|
|
|
LoudNF
New User
| Posts: 2
| Joined: 11/08
Posted: 12/02/08
12:29 PM
|
|
I have not done any computer mods yet. i am trying to decide if a hand held programmer will do the trick or if i should pay some extra and have someone do it for me? As for the valve spring, they are still stock, but i am ordering new ones as someone else had said i needed to replace them. i was figuring this engine should be around the 350HP, maybe slightly more. sure not seeing that yet.
|
|
|
|
|
|
|
Posted: 12/02/08
02:01 PM
|
|
Check into JET performance DST if you want to tune with your laptop. Jet Super chips and Hyper tech all offer hand held tuners for your vehicle. You will see a much larger gain with the software as opposed to the preloaded tunes with the internal mods you have. Your probably floating your valves as soon as you get into your power band. Changing your springs getting a good tune, and loosening up your converter will make a night and day difference.
Good Luck
|
|
|
|
|
|
|