rik881

Hi, first post here.

I have a Avalanche Z71 03. I am a home-schooled back yard mechanic. I want to get some extra power from my LM7. I want both under and above the curve power. One day i'd may be like to go turbo but i think there is not enough space to fit one without redoing the front. I am on a small budget. I have no fear of doing all by myself.

What i'd like to start with is a mild cam and porting the heads. I don't want to go into software yet and i don't want to go carburator because that would be not stroke with my budget. I already have a huge exhaust, Flowmaster iirc. Now i have to decide on what cam to buy.

What heads does my LM7 have? I'd like to buy used ones and port them.
I live in a small country in South America where we have little to no professional tuners so i must rely on what i find on the web and do everything myself.
Thanks in advance for any help!

gagliano7

Your heads are either 706 or 862 heads. Even if you do a small cam and port the heads you will need a tune to optimize your changes. Have the heads milled and go with a thinner head gasket to up compression. You could also put 4.8 pistons in to up compression(your 5.3 pistons are dished) but that will be alot of work. 212/218 cam is the go to cam for a 5.3 in a truck.

Mercier

iTrader: (15)

Some good reading:

https://ls1tech.com/forums/dynamomet...hp-22rwtq.html

MaroonMonsterLS1

above the curve power?? that's quite literally infinite. When people say below the curve, they mean a cumulative of all power between 0 and up to the line on a dyno graph. someone with a very "peaky" hp curve with peak at 500 could have less area under the curve than someone with a very flat graph that peaks at 400.

Onto the topic. Your best bet is going to be either find a company that can do email tuning. You describe your setup, give them as many details as you can possibly think of, and they work with you via datalogging to get an appropriate tune. With heads and cam, there's going to need to be some tuning.

If you're willing to learn, you could get hptuners or efi live and do it yourself with the help of a tuning guide book.

rik881

@MaroonmonsterLS1 Ok that came out wrong, i want to be able to use it as a daily driver, but i also want powerrrrrrr. I am now finishing up stage 0 tuning. Knock sensors and some small stuff.
I am willing to learn HPTuners or EFI live just wondering if there is a program which can be used in different brands but i guess there is none.

@Mercier Trying to understand the numbers but i'll need to dig deeper into that.

@Gagliano I saw some pics of flat pistons are those the ones you are talking about? If i'd go that way i'd use another engine. So i'll always have a spare but but first i want do the easy things which don't require getting the short block out Prices seem to be going up now. The 706 heads or 862 heads you say.? I think i saw a video off a guy porting those 806's. Are they much different? Are they ok to go with? Does the 212/218 cam give a nice sound?

Thanks for your help guys. Appreciate it a lot.

MaroonMonsterLS1

I agree with the above recommendation. a 212/218 is a solid, proven performer. There should be plenty of support on the web for tunes that have that cam and similar mods, making your job of tuning the truck much easier. It might not be the *optimal* cam, but it will definitely provide solid gains and more importantly have plenty of support from others that have experienced this cam in their own build.

If it were me, i'd get the cam with a 111 LSA on a 107 ICL (111+4 if that's how you're used to seeing it). This will make for great valve events to promote solid low end torque. That cam, installed with those specs, should close the intake valve at 58 degrees ABDC. That will give an effective/dynamic compression ratio of damn near 8:1. That's an awesome number considering the stock static CR is only 9.5:1.

It will also open the exhaust valve fairly early which will lose some top end power, but i'm assuming you won't be spinning this lm7 to 6500 anyway so not a huge loss there. If anything, it should help with the sound most guys look for in a cam. If you want a little more top end (say above 5500 rpm) you could go with a larger LSA.

Overlap at .006 is good (around 48 degrees) and should "lope" well enough to be noticed. If it doesnt deliver the sound you want, drop idle rpm, pull timing, etc. You can make a cam sound the way you want at the expense of idle vacuum, drivability, and fouled plugs.

rik881

That indeed seems the 'to go with' cam. Comp cam has one for +/- $400 but i'd like a package with titanium springs. I'd might go for the hardened pûshrods as well. I'll also need a new timing chain since my LM7 has almost 100k miles. There are so many different cams that i think this is going to be a very hard choice.

I put the original knock sensors today, runs much better now. I have 706 heads by the way. Which are the better heads for my application that don't break the bank?

rik881

First thing i'll need to buy is software I guess. I have been looking for which to buy and i think i'll need HPI Tuners. I just don't know if i should go for the pro package or the base one. Base is $500 the other one $650. Does anyone know a better price for this software? I can't seem to find a dyno closeby. I wanted to do a run before and after.

For the camshaft, should i go for any brand in particular or can i just look for the best price? There are so many cams out there that i'm getting very confused.

Mercier

iTrader: (15)

Cam is NOT something where price should be your deciding factor. Give Cam Motion a call and see what you think. Their quality of product is second to none and their advice is free.

See link below..you need HPT Pro for logging a wideband O2 inline with the other sensors...so to me it's kinda required if you are going to tune anything yourself. It also has built-in data logging that you can retrieve later, but I always end up logging directly to a laptop/tablet anyway so I don't use that feature myself. But my only experience is my own 2 LS-based vehicles so YMMV.

http://www.hptuners.com/forum/showth...ce-Differences

And with the assumed need for a wideband O2, your best price is usually through one of the vendors here that will sell you the HPT Pro bundled with a wideband setup.

rik881

So i need software and a wideband. I'll go searching for those later on. There seems to be quit some hp gains from a simple tune. I read some guys make almost 50hp on a stock engine. I always thought software on a NA engine to make very small gains.

Mercier

iTrader: (15)

Tuning is amazing sometimes but 50 seems very high on a stock engine.

MaroonMonsterLS1

Buy the base software. There are many writeups on how to use the egr input on the stock computer as a retrofit input for a wideband. That way, you don't have to pay for the extra inputs that come with the pro.

rik881

I have those EGR holes so that might come in handy. Since i am on a small budget this will be the way to go. I read some also using the ac pressure switch.
Will any wideband do? Seems everybody uses the AEM one. Is the egr hole same size and thread as the o2 sensor's? Do i need one sensor for every bank or just one. Lost off questions, this is all very new to me. I try to learn fast but sometimes i get lost. Years ago i made a rotary engine with carburetor which seems so much easier to me. No messing with ECU's and all.

Mercier

iTrader: (15)

I think he means wiring the wideband into the EGR input..not using the EGR hole for the sensor..am I wrong? How laborious is this? I would have done the same to save a little cash. But now I have 3 LS vehicles to play with and maybe didn't want to have to do the wiring on all 3.

JoeNova

You don't use the EGR hole for the sensor. You have to use an actual 02 bung for the wideband sensor. You pin the signal wire from the wideband harness directly into the ECU where the EGR wire would normally go and then log it using the EGR signal. This way you don't have to spend $200+ extra on the HPT Pro for wideband support.

Mercier

iTrader: (15)

That doesn't sound so bad. And I guess it can be chalked up as part of the install of the WB in that vehicle. I think it may be a bit tall to call it $200 as the bundles with WB probably save you $75 or so..but still $125 is money. I can't say it doesn't exist but I haven't seen bundles for WB + non-pro HPT.

Edit: now that I think about it more, this is actually cleaner than having a dang plug under the dash of the vehicle for the Pro to connect to for the WB signal. I'm going to do this anyway. Any drawbacks/compromises at all compared with logging through the provided serial interface in the Pro unit?

JoeNova

Scoggin Dickey will do a non-pro + AEM WB combo. That's where I bought mine from.

Zero difference in data logging using the EGR port vs the Pro port. Both the wideband and the EGR use a 0-5v. You just have to create a custom PID in HPT using the EGR signal. Rename it to Wideband. Set 0v = 10:1 and 5v = 20:1, and then make sure there is a gauge for it on HPT interface and a line for it on your graphs for logging. Takes 15 minutes to set up. There are dozens of how-to write-ups out there.

Mercier

iTrader: (15)

Look, if we are going to be friends, you're going to have to leave me SOME reason I wasted the extra $200.

JoeNova

Lol. I also log EGTs using the AC pressure port. There are lots of things you can log without the Pro.

rik881

LOl, i thought i started to understand how it works.

@ Merceir you can integrate fuel pressure with the Pro interface, not sure if that will come in handy.

@JoeNova wideband kits come with pro package i saw on this site.

Where will i find the sharpest price on a non pro combo with wideband? I saw AEM UEGO 30-4110 for $180 on Ebay. The BOSCH 4.9LSU is what i need iirc.