L92/LS3 issues.

[ScottT]

i converted the motor over to all ls3 with aftermarket cam, springs, moroso pump, slp underdrivve harmoic balancer, headers, and got an ls3 intake and use rthe l92 stick one. My question is would it be worth getting a used fast 92mm for 500-600? Also has anyone found out how much hp is gained by porting and polishing heads and matching to intake. Also will the ti push rods from an ls7 fit in y engine? And any advice on pistons and con rods, and rockers would be great. Im 23 and in colllege so no time for research and a budget

[Chevelle598bb]

It all depends on what budget you have to work with and how much horsepower and rpm you plan on making. In most cases on 500-550 hp ls3 the fast intakes only pick up about 10 hp or so. If your going all out and can afford it then buy one. Of your tight on money than use the stock ls3 intake and spend the money else where. Porting the heads is another issue of hp and rpm range. Also with what cam you are using. The ls3 heads make awesome power right out of the box. As far as pistons go I use wiseco, cp and diamond. They are all forged from 2618 aluminum and all are very nice pistons. Mahle and srp are nice but are forged from 4032 which is a weaker forging although they are still very strong pistons for a n/a motor. For rods I have used scat, eagle, callies, crower, lunati, ect. I use scat or eagle in lower cost builds (h-beam) and they are great. Scat also has a nice (I-beam) rod that is very inexpensive but works well. Any of those rods will support (700-800hp). Just make sure to upgrade the rod bolts to arp2000 bolts and you'll be ok.

We need to know your hp goal and budget to narrow soles me of these choices down for you.

[Trevor @ Texas Speed]

FYI, FAST never offered a 92mm LS3 intake manifold. The original LS1 cathedral-port FAST intake was a 92mm, but their current cathedral-port, LS3, and LS7 intakes are all 102mm. We dyno-tested the FAST 102mm LS3 intake manifold on our Superflow 902 engine dyno on a stock bottom-end LS3 running our PRC LS3 heads and TSP LS3 cam, and it only gained 6 flywheel HP over the factory GM LS3 intake. The cathedral-port and LS7 FAST variants both show excellent gains, but the LS3 intake is harder to justify. We produced 600 flywheel HP with our 231/236 cam and PRC ported LS3 GM castings through a stock GM LS3 intake manifold using a stock GM LS3 short-block. This was with 11:1 CR. Our PRC CNC LS3 port will pick up just over 30 flywheel HP over the unported GM castings without any other changes.

With respect to the LS7 pushrods, they are not titanium. They are a 3/8" diameter with 5/16" ball ends and are 7.800" in length, so they are way too long for your LS3 setup. Depending on the base circle of the cam, lifters used, thickness of head gaskets used, and amount milled off the cylinder heads, you'll likely be in the 7.35" to 7.425" pushrod length. A standard 5/16" diameter will also work just fine.

We use Wiseco pistons in 99% of our short-block and long-block engines, and they are definitely among the best on the market. We build over 300 LSx short-block and long-block engines every year ranging from basic N/A setups to 1,200+ RWHP boosted applications. The Wiseco pistons offer the best right out of the box. They will come standard with a steel top/napier 2nd ring set, as well as lowered ring lands, should you ever look at a power-adder in the future. They will not require a wrist pin upgrade until you surpass 1,200 flywheel HP. At that point, you will want to upgrade to their HD tool steel wrist pins. For connecting rods, The Lunati 6.125" H-beams are among my favorite. If you are looking to produce over 900 flywheel HP, I would recommend stepping up to the Callies I-Beam connecting rods.

For the rockers, it will be best to stick with the factory rocker arm bodies and upgrade them with a Comp Cams trunion upgrade kit. The factory trunions use needle bearings, and if they come apart you'll have 33 needle bearings floating around in your engine! The Comp Cams trunion kit will alleviate that issue. We recommend sticking with the stock rocker arm bodies because of their light weight. So many of the aftermarket rocker arms add a LOT of valve train weight, which will lead to valve float issues considering the massive 2.165" intake valve of the LS3 heads. Unless you're doing something really extreme that requires a shaft-mount set of rockers, the GM rocker bodies with the upgraded trunions will be your best route.

Let us know if you have any questions or concerns.

Thanks!

Trevor
Texas Speed & Performance

[GeoffP]

Great info Trevor - thanks for the post!

[Trevor @ Texas Speed]

Great info Trevor - thanks for the post!

no problem! always glad to help! :) Don't hesitate to PM or e-mail me at [email protected] with any questions or concerns.