Hey guys,

Same old question, just tailored to me. I have a 2000 silverado with LQ4/4L80E and NP8 transfer case. Looking to add some good hp and tq without breaking the bank. I wanted 400hp, but its looking like that is out of the question for the money I want to spend. A little background: I am mechanically inclined (aircraft mech) and motivated to build a beast. I picked the truck up a few months ago for dirt cheap with 237,xxx miles. It runs good after I spend $1k tuning it up and replacing worn parts. What I have in mind: Cam, LT headers (sitting in garage), port and polish stock cast iron heads, stock cats/dual 40 flowmasters, 4.10s in front and back, a tune to wrap it up and finally some 33'' all terrain tires. Since it is a mud truck I want to leave the stock air box to deter water (I'm partial to wix filters.) Eventually I will replace the tranny and t-case when money allows, but for now I'm focusing on the engine. Biggest issues after months of research: what torque converter to use?, what pushrods with milled head?, how much to mill heads?, what head gaskets to use?, is it worth milling porting and polishing stock heads?, and what cam to wrap all these up? I was also hoping to keep the short block, keeping in mind that the oil comes out clean and looks good. Any suggestions and info would be appreciated, especially on the stock bottom end. I dont want to build a motor that will bomb a month later just to save a few dollars, but if it will keep trucking I could put that $1200 towards the tranny.

 

It's hard to tell how long any specific engine is going to last. My 02' has got close to the same mileage, but it still runs like a champ, has perfect oil pressure and only some piston slap or valve tick on cold start up (which is 6 months of the year up here LOL).

I wouldn't worry about having to rebuild, especially if your just gonna add 30-40HP and it runs good otherwise. If you are worried, start looking at CL and all over the place for a cheap lower mileage engine to put money into.

You can build it up slowly, but you get to do it right and save some money. That way, if you have a catastrophic failure, you won't have to scramble and pay out-the-@$$ to find or build a replacement.

It's not always an option, but I highly suggest this route.

 

I would ditch the cast iron heads. A set of 317 aluminum at least can be found from $50 to $150 then mill some or a set of 243/799 would be the better out of the choices they go from $200 to $300. Either one of them plus a decent cam will make a nice ride.

 

lq4 never have iron cast heads. This is ALWAYS alum heads. For your info. Welcome to our website.,

 

I always heard that the 99-2000's came with iron heads and were still designated as LQ4 engines. They isn't much of a difference, other than saving around 30-40lbs.

 

The LQ4 did come with iron heads in 99-00'. You can come curl them out from under the hood if you would like. haha. As for the heads, my cast iron are the same as the 317s as I have read and I am not worried about the slight weight difference in them considering the weight of the truck. My main concern if pulling 325-350rwhp or so with the compression increase, exhaust, cam and tune. I dont think that is unreasonable, but I want everything to bolt back up so I do not have to rewire or fabricate anything. Like I previously posted, I have done enough research to know what I believe is cost effective for my gains, and switching the heads did not seem the way to go (unless I go with trickflows $$$), since I can have mine machined/polished/ported for less than 500 out the door.

 

You’re right in the 873 iron heads are pretty much duplicates of the later 317 aluminum heads with the same combustion chamber volume of 71.06cc, intake port volume of 210cc, exhaust port volume of 75cc, intake valve diameter of 2.00 inches and exhaust valve diameter of 1.55 inches. I too believe you may still be best served by picking up a newer set of aluminum heads though and not specifically for the weight savings they will afford. One you could be working on them while still driving your truck, second being a non-ferrous material will be a whole lot easier to port and are easier to repair if it became necessary, third also being a non-ferrous material will aid in them pulling heat out of the combustion chamber faster. This in of itself will not make any more power, some would go so far as to say all things being equal the additional heat in the chamber would actually make slightly more, but when adding compression to the mix the aluminum heads will combat detonation and in a relatively heavy vehicle such as yours may be of some benefit, especially when it comes to trying to run additional timing. Again, while the 317’s are basically identical to your current heads and can be found reasonably inexpensive and could be machined to raise the compression some, I would look for some of the newer 799 (243 equivalents), as they would raise your compression basically 1 point with no other work needed (retaining full deck thickness) and being considerably newer would in all likelihood need less work refurbishing them. If your current heads needed any work to the guides or valve seats, the savings you were looking at with your original heads could quickly be diminished.