Hello all - I don't post much here, mostly on performancetrucks.net but I wanted to see what you all thought of my setup and dyno numbers.

I feel like I'm 50-70hp down from where I should be but everyone is telling me that my 37" tires, Dana 60 HD rear axle, and 4L80e is soaking it up.

Not being too familiar with a cammed big cube motor, it's hard to tell if I have a miss. The Tuner didn't notice anything, but under part throttle mid rpm's I feel something is a bit off.

I am changing out the Holley Hi-Ram for a ported L92 intake manifold to try and gain some bottom end back. I noticed it wasn't port matched to the heads very well, so maybe that could be causing some lower numbers.

Thanks!

Iron block
Stock Ls3 heads 65cc chambers
Blower cam but I'm NA right now:
specs are LS1 2131R/2133R HR15
o .653” int
o .660” exh
o 115 LSA
o 243 int dur @.050”
o 251 exh dur @ .050”
90mm dbw tb
Holley hi ram
80lb deka
1 7/8 speed engineering header w/ their 3" dual x-pipe
Manley 10cc dish piston
11.4 compression
4.070 bore
4.100 stroke
C5r single roller w/ cloyes adj gear set straight up
Mighty Mouse catch can w/ pcv
4l80e hd2 kit
Hughes 3000 billet triple (Which is actually a 2200rpm stall as I found out after the tune)



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my response won't help validate the numbers much, but yes, you do have a very heavy drivetrain which is going to make the numbers seem smaller than what they really are. I do believe if you ran that motor in a car with a 26-28" tall tire you would probably see a lot more horsepower...how much, I really am not sure.

You noted your cam was spec'd to run with a blower. If you have the blower, I would throw it on and see what it does. When my dad ran a nitrous cam in his 68 camaro, it was huge and felt like a dog as he wasn't spraying and using it how it needed to be used. Switched over to a cam that was more suitable to be ran NA it ran it's *** off. Literally night and day.

I know this doesn't help too much, but if you have the blower ready to go, I would install it before going back to the drawing boards, it might really wake up with a few pounds of boost feeding it.

 

Thanks and yes I agree about this cam, and after doing a lot more reading I think I'll be going with a smaller cam designed for NA use. When I get the blower, that's when I'll use this cam. I think if my heads were ported I'd be in a much better place and I'm hoping the truck manifold will help out as well.

 

Those giant off road tires are hurting you, probably as much as the rest of the heavy driveline, maybe more. You're probably in the ballpark of where you should be.

 

True - just the tire weighs 80lbs. So I'm probably close to 110lbs each with wheel and air, and they have a fairly aggressive tread pattern.

 

I agree with the above on the big wheels and tires killing your horsepower rating on the chasis dyno.

 

Yep, that is unsprung mass that takes more power to turn. Also realize the height hurts too. That height acts as leverage against the engine, rather like how larger brake rotors use leverage to provide more stopping power.

 

So much better with the L92 intake. Truck actually has some torque.

Here's a vid

It's home ported so it flexes a little bit but my external support rails seem to be helping keep things together.


And I also hand ported the throttle body - it needed about 2mm taken out to port match to the L92 plastic intake but I'm sure this helped a bit too

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