Engine build up

[JayDubBlazer]

Last year I put a GM crate engine in my truck. It is listed at 260HP and 350 ft-lbs. Here are the other numbers…
• (4) Bolt main block with a (2) piece rear main seal.
• Cast Iron Crank.
• LT/LT4 Powdered Metal connecting rods.
• Cast Pistons, (dished).
• Hydraulic flat tappet cam, (.383” intake / .401” exhaust) and a 112-degree lobe separation.
• Cast Iron Cylinder heads with a 76cc combustion chamber. (Non vortec design)
• 8.5:1 compression ratio.
Currently I am running with a performer intake, 1406 Edelbrock carb, HEI, and headers.

Here is my question. What do I need to do to get is up to about 330-350 HP and 400 ft-lbs.? Also could someone explain why performance heads have smaller combustion chambers? What are the difference between hydraulic, mechanical, and roller lifters? What role does lift play in the heads isn’t just all the duration the valve is open?

[smokekiki]

The smaller chamber will bump your compression up.The shape of the chamber and runners will increase flow.Basicly the solid and hydrolic lifter look simular.The hydrolic has a "piston"inside that is cushioned by oil.It is to keep the valves in adjustment for a long time.Solids will hold the adjustment at higher rpm's where the hyd. will colapse and limit the revs on the high top end.Rollers are traditionaly solids with a wheel on it.Newer engines have hyd rollers.It is a lot more tech then that as the cams are ground different for the lifters.

[bigjimzlll]

the lift of the cam allows for more flow..lets say you have a cam that has 300* of duration and only .400 lift..your heads flow 200 cfm at .400 lift...and less at lower lifts. You only are at the .400 lift for a split second..sure the valve stays partially open longer..but at a lower level of flow..now take that same duration at .600 lift...say your heads flow 270cfm at .600..now you only have a spit second of max lift..but you have two lifts at .400(and higher) opening and closing

[superchevy]

That's a tbi crate motor. As such, it has a very mild cam in order to operate with the restrictive tbi induction system/computer.
To get to the 330 hp range, change the cam and step up to a Performer RPM or AirGap intake, as the Performer is barely better than a stock intake in my opinion.
You might check out the Edelbrock Performer RPM cam/intake combo.
SC

[adkphoto]

I just did basically what you are asking about.... I took a "stock" Goodwrench bottom end (crank, rods, pistons) and upped it to about 330 - 350 hp based on comparison with other crate engine specs (not dyno'd). It's pretty radical for a one-year-old engine in that you'll be scrapping a lot of parts, but it'll definitely get you the results you want.

Here goes:
Scrap your 76 cc heads and get a set of Vortec heads. I had my heads built-up better than stock with larger valves, LT1 springs, and screw-in studs with guides, but if you're careful to stick with a mild-lift cam that shouldn't be necessary. There are lots of posts here about the lift abilities of stock Vortecs but I can't remember what it is. Mine are good for 0.5" which is more than I'll ever need on this engine.

The Vortec heads' smaller combustion chamber will bump your compression up for a nice torque and HP boost. Built-up Vortecs are available from lots of places these days. I got mine from a shop in Phoenix called Performance Chevy. Pace Parts and Scoggins Dickey also have them. Check their web sites for prices.

The Edelbrock Performer system is dyno-matched to work together. I used the Performer carb, cam, and intake. The Performer RPM system will give you more top-end. The carb is a 600 cfm unit (super easy to tune... but you already know that). Cam has 114 deg of separation and 0.42/0.442 lift with 1.5 rockers. Be careful to get the Vortec intake with the Vortec heads as the bolt pattern is different.

I also bolted on a set of Flowtech headers. 1.5 inch primaries and 3 inch collectors, ceramic coated to resist rust. The small diameter collectors (compared to 1 5/8") make great low-end torque. They may hurt top-end HP, but that's not where I use my truck so I didn't care. 2 1/2 inch pipes and DynoMax mufflers take the exhaust away.

While you're at it, upgrade to a double-roller timing chain, roller-tip rockers, and a heavy-duty oil pump. HEI with an Accel coil provide the juice to my setup.

I don't think you're going to be able to do what you want without at least rebuilding the heads. The heads you've got are not going to flow as well as you need them to without port work of some kind, and the low compression robs you of power. Chances are the springs and flow abilities wouldn't support a bigger cam either. In my case, it cost less to buy the Vortecs than it would have cost to rebuild my stock heads.

Alternatively, I suppose you could swap the pistons for flat-tops to bump up the compression, but that doesn't help the engine breathe any better.

David

[JayDubBlazer]

Thanks for the info guys

[JayDubBlazer]

What are good casting numbers for vortec heads? Where is the best place to get them

[smokekiki]

Not sure what all to look for in the junkyard.If you want new scroggin dickey has vortec kits.You get the heads with light weight retainers,z-28 springs,rockers, and a edelbrock rpm manifold for $910.These are modified for .550 lift.For another $40 you can upgrade to an airgap.

[Wreck]

check out this set-up..man this truck flies and sounds way cool...maybe can get a good idea from his engine.


http://www.geocities.com/ryan98gt/c10specs.html

I would love to have his engine in my 72.