I have only been a member for a short time, but have been chasing horsepower for years. As I read through all the forums and see all the different levels of power made by various setups, it makes me wonder why my engines has been such a dud. Here is my current configuration:

11.5:1 forged short block
afr 210 heads mamofied
fast 102 Matched
LT headers 3.5” Y
Corsa 3” exhaust
no cats
Corsa CAI
TSP Torquer V4

i have only managed to make 370 whp through a 6l80e with 3.90:1 gears.
am I expecting too much, Or does this sound low?
is more info needed?

 

Ok, I’ll see if I can help. Yes it seems WAY low so I have a few questions:
1. What gear was your 6l80e in during the dyno pulls?
2. Are you using heavy rims?
3. What tire?
4. What rear end?
5. Header primary size?
6. Are you sure your valvetrain is setup correctly?
7. Timing?
8. Air/fuel ratio?
9. What fuel?
Your cam isn’t responsible for that low of a number, but I would think you could get more power with a custom grind for your application.

It may not be one thing but it could be a combination of things. Have you ran the car at the track or tried another dyno?

Sorry for the long post, but hopefully we can help diagnose the problem.

 

3rd gear with the traction control/antilock fuse pulled
Factory rims 20" 275/55 20 Michelin's.
Factory 8.5" Chevy Tahoe
1 7/8" primary speed engineering long tubes
I can only assume it is correct. I had a local shop build the engine and they seem to do good work
I am not sure where the timing is. I know it clatters with 93 and runs decent with e85. It is a flex fuel vehicle but has not been tuned for e85. Factory flex tune
AF. 12.3 WOT

 

What does your exhaust look like behind the headers?

Have you done basic checks for a dead cylinder?

 

It is 3" single out with a corsa no cats and a 3" resonator after the axle . Have not checked compression but it was a fresh build last year March.

 

Ok. With your headers back you may as well have stuffed a banana in the tailpipe. When I did my first Mamo build I had major dyno disappointment. Dropped the Y. Redyno, up 70. Cats on a new y were plugged, the merge sucked, and it could not flow.

Second. Compression check is not the same as a dead hole. While engine is warming up spray primaries with water. Or get a temp gun. Cold primary means it's not firing. Many possible reasons not just compression. Wiring, grounds, plugged injectors. But if you confirm all eight are about the same temperature, you can rule all of that out.

Third. Post the graph. Sometimes power is low just because the dyno operator let up.

 

I was suspect of the exhaust as one contributor.
I will check the cylinders in the morning.
I will post the graph in the morning also.

 

Temps rose evenly. I stopped measuring at 400 on each header primary approximately 1-1 1/2" from head with laser thermo.
Graph included

 

So is this engine in a Tahoe?

 

Ok. So no dead holes. Good. And on the graph he lifted just as it peaked so it is not like he pulled out while still climbing.

So I would look to the y and catback as your bottlenecks first.

 

Can your fuel system keep up?

 

Keep in mind those 20” Tahoe wheels are heavy. With tires they’re around 80 lbs each. Now that doesn’t account for everything but it does play a role.

Exhaust could definitely use improvement as well. Your headers are ok though.

 

I always new the exhaust was my short fall but never thought it could be that significant. Learn something all the time. I am in the process of changing that now.

 

I doubt all the issue is in the exhaust. I have a 346 with BTR stage 2 cam, which is smaller than yours, a DLS2 intake, 1 3/4 headers, catted y and 3 inch exhaust and made 408. You are probably 40-50 hp low for your combo.

 

I am sure there must be other things. I really prefer the under the curve power but you still always hope for a good number. I was going to do the exhaust anyway.

 

Do you have access to a hub dyno?

 

I'm not sure.

 

I have a custom grind cam from Bob at Cammotion I have yet to install. Wanted to get some opinions about possible issues before I just swapped cams. I am going to devote some time to this tomorrow and go over everything thoroughly to make sure I'm not missing something silly. I appreciate everyone's input.

 

I think you’re on track. Let us know how it turns out.

 

Will do. Thanks again.