Hi,
I have a different need than most regarding modifying my 5.3 Tahoe.
I want max possible torque below 2500 rpm, with out loosing my stock Hp.

I am not willing to loose one single Nm under 2500 rpm, for one extra Hp on top, if you see what I mean.
The ruels are:
Not modding the short block, bore or stroke.
No FI

All other areas are open to modification.
I will also use E85, withch has 104 oactane.
I also use HP tuner, and think I know what I am doing.

What would be your recomended modifications to get the highest possible torque numbers from 1000 to 2500 rpm, with out loosing my stock Hp?

Br //

 

I have a special Comp Cam Grind Cam that works wonders for this. See Signature.

Steve

 

Comp just released 3 new grinds just for trucks, one is pretty much the same as mine (see sig), only on a 115 lsa. My cam is great for a daily driver, and I didn't lose anything down low. Check out Vinci's website also, they have a bunch of different truck cams to choose from.

 

Ok Thanks!
If I increase my compression to, say 13-1, ( Ok with E85) would that change my cam selection in any way compared with if I keep the stock compression?

Remember, I am not after "not loosing any tourque", it is Tq I want!
I could actually sacrifice som Hp on top, if I get more Tq from 1000 rpm.

Br//

 

Tahoe,
You are talking about maximizing low end torque. How do you plan to use the truck?

My first aftermarket cam was a Comp 54-212-11 which is a 212/218/114 LCA cam. It has great mid to upper range torque (beginning at about 3,000 in a 6.0 L), but I lost a lot off idle through 3,000 RPM's. That's why I went to a smaller cam and it's much stronger down low (by over 20 pounds feet) and weaker up top by over 20 HP. It's still better than the stock cam throughout the RPM range by a long shot.

Steve

 

I will be doing some towing with my new caravan,
http://www.kabe.se/caravans/models/rh880tdl/
and general high way cruising. (towing is done at 50/55 mph and cruising at
60-70 Mph in Sweden)
I can use up a tank full of gas, with out once seing over 2000 rpm.
(without trailer)

I have adjusted lock up to hold on even when i have ambient air pressure in the inlet manifold in OD. That is great, being able to drive it more lika a manual trans car.
Personally I se no reason what so ever to spend gas just to keep the engine on higher rpmīs. I do how ever understand the reason GM sell us the trucks that whay, to lower ther Nox emissions to comply with regulations.

That is the reason I am so focused on low Rpm Tq.
The Hp are plenty as is, doesnīt matter if I have 299 or +/- 15.

Br//

 

I wouldnt go any higher than 11:1 SCR compression and 7.1 DCR Ive always heard that e85 was closer to 110 but even with the greater octane rating I would leave some room with the compression as soon as you put a huge load on the engine with the converter locked at highway speeds it will be very prone to detonation regardless. Plus you should be able to run whatever timing you want.

The exhaust side will be very important and I would go with mid length or smaller headers with smaller collectors

 

Tahoe,
I would highly recommend a small duration cam like the one that I am running 200/206. This cam has a lot of low end torque and runs out of breath above 5,000 RPM's. It does very well for my heavy truck and trailer. I'ts economical too.

Steve

 

Intresting!
Yo donīt happen to have dynoed your truck, have you?
It would be very intresting to se the Tq curve for your combo.

Br//

 

The 200/206 cam isn't really worth swapping for, IMO, it's not that much bigger than stock. The Cam Motion 205/212, .550/.544, 144+4 I had in my Avalanche, however, is. Keep in mind that I had a 5800 lb. vehicle with pretty much the same requirements as you, and was saying the same stuff you are: "No low-end loss!" I wanted to keep the stock torque converter. I got what I wanted with that cam - around 15 RWHP all across the powerband, including right off idle, and 20 RWHP peak - and it pulled all the way to 6,000 RPM.