box_dime

Yup, another one. There seem to be a million. Let's make it a million and one.

I've been wearing out the search button as well as google. I am trying to plan out my build. This will be my first venture with an LS based engine. I figured I might as well include all the information and numbers I have been able to gather to possibly save people some of the hassle I went through in further searches. I literally have about 20 different threads and 4 or 5 different sites that I went to in order to gather everything into one spot.

It seems this is a rather popular combo, yet it seems there is no real solid info all in one place. If any of this looks wrong to anyone, please feel free to correct me. I'll make edits if needed.

Anyway, my reason for the post is as follows. I am building a bit of an abstract vehicle. It's a 1990 S10 that I just picked up. The simple think to do would be to turn it into a drag truck, however I don't think simple. I want to cage it, stuff some C4 ZR1 17x9.5F/17x11R wheels under this thing with a custom 3 link rear suspension, double adjustable QA1 coilovers and some big Willwood calipers and rotors and make this thing handle. Why a truck? Why not!

So the dilemma I am facing is cam selection (and yes I've spent a lot of time in the cam guide post). It's always easy to just throw a GM Hotcam, TSP Torquer V3 or a LG G6X3 cam in, but it may not be right for what I want the truck to do.

I know PTV clearance can be an issue with this combo. I have decided to purchase a set of aftermarket pistons rather than go the flycut route. I have never done fly cutting and would like to keep this build completely in house. The added security of having a set of decent forged aluminum pistons in there is nice too. For that reason I chose these Wiseco Pro Tru Street Pistons to use.

As for what I am looking for, it may require a custom cam, or maybe one of you more well versed in this area may know of a good off the shelf cam that will allow me to keep the price down. Maybe it's even one of the ones I listed above!

What I am looking for is something that will hold good power up to 6800ish with good mid range response in both power and torque and decent drivability. Peak power numbers don't mean as much to me as a nice broad and healthy torque and power curve. The flatter the curve, the better to me for what I want. I would really appreciate some input from anyone willing to edumacate me. I will be topping this engine off with an Edelbrock RPM Performer Intake and a worked over Holley 750cfm 4bbl carb. The truck will see some road course use, some street use and some strip use and will primarily be run on 93 octane, however I do have access to 110, 112 and 116 pretty much any time I want from the speedway where I race my oval car that is a mile and a half from my shop.

Stock LQ9 Shortblock Info

• Bore: 4.000"
• Stroke: 3.622"
• Rod Length: 6.098"
• Piston Compression Height: 1.338"
• Block Deck Height: 9.24"
• Deck Clearance: -005 (.005 above the deck)
• Head Gasket Compressed Thickness: .053"

NOTE: Wiseco Pro Tru Street Pistons +4cc Dome to be used

Stock LS3 (821) Cylinder Head Info

Flow Data (Intake tested @ 4.060 bore, results will vary)
Valve Lift .200 .300 .400 .450 .500 .550 .600 .650 .700
Intake:--- 156 226 276 294 310 324 332 332 308
Exhaust:-- 120 158 183 190 194 199 202 204 205

• Intake Runner: 260cc
• Exhaust Runner: 89cc
• Intake Valve: 2.165"
• Exhaust Valve: 1.590"
• Valve Angle: 15º
• Combustion Chamber: 68.4cc
• Max Lift (Stock Springs): .570

Compression Ratio for Combo with Stock .053 Head Gasket: 11.04:1

Compression Ratio for Combo with Cometic #C5751-070 .070 (4.060 Bore) Head Gasket: 10.59:1
Compression Ratio for Combo with Cometic #C5751-066 .066 (4.060 Bore) Head Gasket: 10.69:1
Compression Ratio for Combo with Cometic #C5751-060 .060 (4.060 Bore) Head Gasket: 10.85:1
Compression Ratio for Combo with Cometic #C5751-056 .056 (4.060 Bore) Head Gasket: 10.96:1

NOTES: T56 Transmission, Patriot Headers with 1-5/8" primaries and 2-1/2" collector dumped out through electric cutouts.


Thanks in advance!

-P

tech@WS6store

iTrader: (2)

For that setup a simple texas speed ls3 stg3 cam 231/236 cut on a 111 lsa and 108 icl would be just fine. Use their dual springs and youll be fine. going larger like 240+ exhaust would sacrifice the bottom end and isnt really needed for what you want to do in my opinion.
It would make the power at 6800 on that single plane yet have good mid range and manners

tech@WS6store

iTrader: (2)

Or this one. about the same.
http://www.ws6project.com/user_stor/catalog/product_info.php?cPath=235_426_73_773&products_id= 5636

box_dime

You know, I feel pretty dumb because I didn't even realize that TSP provided dyno sheets on their website that go with their camshafts.

The power and torque curve of that cam in the LS3 crate they dyno'd it in, looks fantastic and it looks like it makes 400hp+ from about 4400rpm on. I A/B/C'd it between the Stage 2, 3 and 4 just for comparison sake and to satisfy curiosity and the Stage 3 is definitely the best to me.

Judging by the fact that my engine will be a 6.0 vs the 6.2 LS3, but will have pretty much the same compression ratio I can only assume that I would probably lose 10-15 numbers off of their peak numbers with the loss of displacement, however I am not sure how the Edelbrock Performer RPM intake setup with the Holley 750 on top will affect that.

Thanks for the info and suggestion, this one has been bookmarked and is at the top of the list for sure. Curious to see anyone else's insight or input too, but you very well may have just made the decision for me lol

tech@WS6store

iTrader: (2)

Dont get too caught up in subtract here and bench racing. Im sure the cam will work well and likely give you what you want. either one.

box_dime

Yeah, it's kind of hard to beat what you showed me already for sure. The only thing that would make me change my mind from the TSP Stg 3 cam is something with a little more of a boost in lower rpm power and torque, but from my understanding from what I have read about the LS3 heads, you give up a little bit of that regardless due to port design.

If my curves ended up anywhere near what the TSP dyno sheets show, it will definitely perform perfectly for what I want. I may even go after a .066 compressed head gasket to bump it to 10.84:1.

tech@WS6store

iTrader: (2)

Stock head gaskets are .053. If you want better power down low youd have to use a smaller cam or change the icl a little to help bring up the lower end. You dont sacrifice with rec ports, your overall goals will determine what you are sacrificing. making power to 6800 will decrease your power down low. Getting a tad smaller will still make good power and maybe better down low plus cutting on a narrow lsa like 111 or 110 but may not have the duration to carry to 6800.

Youre basically running an l76 which isnt 11+ cr on stock head gaskets

box_dime

I saw anything from .051-.053 on stock thickness, so that was close. I'll adjust the numbers in my original post to reflect that. It won't change my original CR #s too much.

Guess I misunderstood some of the info on the heads. I thought as it was being explained in a couple places I read that the rectangle ports flowing more air would sacrifice a little down low over the cathedral ports. I'm still trying to read a bunch of stuff and understand more about these engines. I'm so use to working with the old Gen 1 SBC, and my camshaft specs have pretty much always been dictated by rule books.

zachm89

iTrader: (14)

From the numbers provided, Im coming up with 10.5:1 compression with a factory .053 compressed head gasket. What calculator are you using that you're coming up with 11.2+?

box_dime

I have always used the Summit Racing Compression Calculator. It's never let me down.

Are you taking into account the -5cc DSS Pistons I linked that I will be using to avoid flycutting? When I go to 0cc for OE Flat Top pistons, I get 10.54:1

zachm89

iTrader: (14)

I was figuring with flat top pistons, but with a -5cc relief youd essentially be lowering the compression even more. If you calculated the dish backwards as a +5cc dome top you'd be at your 11.2 number. I'm thinking with your setup and -5 pistons you're going to be right at 9.94:1. Gotta be careful with the + and - on the compression calculators. Just wanted to make sure you input all the info correctly so you're not way off on your compression number. Trust me, I've done it myself before I realized I fat fingered something in the calculator.

Edit--

I just took a look at the Summit compression calculator. It's backwards from all the other ones I've ever used. They use a negative number to figure for a dome top piston and a positive number for a dish. Not really sure why, because to me thats back asswards. Any time you use a dished piston, youll be lowering your compression and with a dome youll be raising it. So going from a -5cc dish back to a flat top wouldn't make sense that you'd lose compression with the flat top as opposed to the dished piston. Hence why an LQ4 with factory dished pistons have a lower compression ratio than an LQ9 that has flat tops. So I stand by what I said originally, with a -5cc piston and everything else in your setup, your compression will be somewhere in the 9.9:1 area with a factory .053" compressed gasket.

zachm89

iTrader: (14)

Download the Cam Motion compression calculator. It lets you also figure in your head gasket bore diameter and intake closing angle to provide with accurate Static and Dynamic compression. Pretty handy. And it doesn't use backwards values for dish/dome pistons.

box_dime

With the -5cc piston, according to how they figure it with Summit, you are effectively removing 5cc from the combustion chamber area. -Xcc pistons are dome, +Xcc pistons are dish. In this case, the -5cc piston is effectively giving me a 63.4cc combustion chamber on the LS3 heads with the engine at TDC.

The piston I chose is linked to Summit's site. They list their dome pistons as (-)cc and dish pistons as (+)cc, using their calculator with stock gasket, I get 11.2:1 this is why I use Summit's link for calculator and to reference parts specs.

box_dime

I'll look into that

box_dime

I'm curious now if anyone else has a problem with my math on this?

zachm89

iTrader: (14)

Still backwards in my mind. I'd check with DSS rather than Summit. Give them the part number of the pistons you have, and ask if they are a dome or dish style piston. Everyone else (besides Summit apparently) uses negative numbers for dish and positive numbers for dome. Reason being, they aren't calculating it by a -5cc piston is removing 5cc from the combustion chamber. -5cc to a piston manufacturer is 5cc cut out of the top of the piston, essentially making the effective combustion area 5cc larger. Where as a +5cc dome piston would be adding 5cc of material to the top of a flat piston, and effectively making the combustion area smaller. I'm not one to pick fights or argue over stupid **** but call DSS to find out for sure what you've got. Because IF I'm right, and the pistons you have are in fact a -5cc dish because of the valve reliefs, you're going to be way off on your compression and that could negatively effect you cam selection.

zachm89

iTrader: (14)

I don't think your math is wrong, I think Summits calculator and how they have their **** listed is wrong. Everywhere else in the industry when regarding pistons and dish/dome values, dish is negative and dome is positive. Honestly, I hope I'm wrong and you do in fact have a 5cc dome piston for the higher compression. But I'm afraid I'm right, whivh is why I brought it up in the first place. I know I for one would be pissed to put an engine together expecting 11:1+ compression and having far less than that due to a numerical error from Summit.

box_dime

I'll be on the phone with DSS once I get off work at 5. I will post the result here.

ss454327

iTrader: (10)

You are backwards. The -5cc is subtracted from the piston side which means it makes the chamber volume 5cc larger.

box_dime

Good catch both of you, Summit's site is definitely backwards then. I snuck outside real fast and called DSS instead of waiting until 5, and DSS confirmed that their -5cc is as you both stated.

My error, thanks. All of my info will be updated shortly.