taman86

iTrader: (19)

I'm looking for some advice and some educating. Here is what I've been mulling over in my head:

ls2 block over bored to take advantage of heads flow
ls3 top end with gm cnc heads factory manifold 92mm cable tb 100mm maf
stroke it
custom tailored cam
1 7/8 headers with y pipe and cat back for ground clearance
ported oil pump
Coated bearings for reduced friction

the overall goal of the engine:

1. Have a low usable torque range
2. Max shifting rpm of 6700 to 7k
3. Be a solid and reliable piece that can take some abuse without hesitation on track
4. Be 91 octane friendly

so my questions are this; how far can the ls2 block be overbored safely? I've seen the iron blocks punched out to ls3 bores but I'm not too sure about the ls2. Also does anyone have any info on clearance specs? Would a 4 inch stroke be sufficient or is there anything to be gained from a 4.125 stroke and still be pump friendly and what would be necessary to run that long stroke? Also for the bottom end i was looking to do lightweight pieces, not anything super lightweight. I'm sure I'm overlooking things right now, but I'm looking to reduce as much friction and rotating mass as possible, so what is everyone's thoughts and recommendations?

thank you

TheC5Surgeon

I am also planning a ls2 build. Looking to stroke to 392 cubic inch with a 3.9 crank. Some resources state benefits of a 3.9 vs 4.0 stroke crank for daily driving applications include more piston stability in the bottom of the bore among other things. I have also read the ls2 block does not tolerate much overbore past 20 thousandths or so.

A.R. Shale Targa

iTrader: (2)

taman86

iTrader: (19)

Great info thank you. So why not a 4 inch stroke with 6.125 rod? What do you mean by the wiseco piston? Is it specifically designed to run a stock length rod?

KCS

iTrader: (20)

taman86

iTrader: (19)

thank you for all the info, i was stuck at that point but this really opens up a lot of options

taman86

iTrader: (19)

If i use the 4.125 crank and 6.125 rods what would the cr be using stock ls3 heads and head gaskets? Is there a formula to calculate that?

Also what are the differences for bearings like king or clevite?

something else that has had me wondering, how do you choose what oil to run cuz the last thing i want is to spin a bearing from clearances being too tight and running the wrong oil thickness but i do know thinner oil means more hp. It seems so simple but something that can be over looked

KCS

iTrader: (20)

handyandy496

iTrader: (9)

I built mine to 418 using an ls2 @ .030 over with an eagle 4.1 stroke crank, scatt 6.125 rods. Arias has an on the shelf piston kit for 11.6 and 11.7 static compression. I used short travel lifters with a smallish hyd cam 235/250 specked for pump gas, Stock ls3 intake and fast 92. It works perfect for good street ability. I'm using the gmpp ported ls3 head. 68cc untouched. This was set up for lots of street use, a daily N/A using pump gas. When I had it machined I told the machinest doing the honing to make the piston to wall clearance as tight as possible on the edge of the Arias spec's. 4 years later I have no oil control problems at all like everybody says they will. lol. This was a relativity cheep build. The thing regularly will see 7300 rpm shifts when showing off. I'm not advising this of course but it's a testament of it's reliability. Performance in a stock heavy 98 firebird with a 9" rear and suspension ad ons @ sea-level is in the 6's at my local 1/8 mile. The guy who specked the cam says he does not believe that this heavy of a car will run 10's but I do have prof of the 6's. I run BR6es plugs and started at 21 degrees timing for pump gas. As the engine wears in I will be making some changes more towards just racing it street to track. I did gap the rings when built to .025 for the use of No2 for after about 10,000 miles of hard wear on the pistons. I also ran a .035 thick cosmetic head gasket for a slight edge in the squish area with no problems of interference noticed. This block had .005 deviation in deck height corner to corner. It is a stock non machined
(non resurfaced) 05 gto block.

tech@WS6store

iTrader: (2)

Im building backwards then. A 333 ci ls2. Our 4.030 rpmspeed hd 6.0 pistons with hard anodized top. Moly rings. 4.8l rods and crank. and i fully expect it to pull to 7500-7800.

On the stock 3.622 crank part you can use our hd pistons and bore to 4.030 safely and build a 370.
Our complete rebuild kits are $699 and come with everything needed save for cam pushrods springs crank and rods. Basically less than most forged pistons.

Ddnspider is spinning his to 6800/7000 with no issue in an LS1.

Let us know if we can be of more help!!

ColeGTO

iTrader: (3)

LS3 Stock crank, stock rods and stock rod bolts with SRP 4032 pistons and spinning it to 7100 for almost 5,000 miles so far. I'm not worried.

A.R. Shale Targa

iTrader: (2)

99 Black Bird T/A

iTrader: (4)

gm cnc heads - from what I've read I would get a different set of heads. Intake runners are way too big. Might be OK on a 454 but too much for 400-420 cube LS in my humble opinion unless it's a very high rpm motor.

stroke it - yes, makes for fun daily driver Correctly build LS1, LS3 etc are fine with 4 inch stroke. One of the keys being the correct Wiseco pistons to avoid being an oil burner with piston rock. Both of my strikers have the trick Wiseco coated pistons & 4 inch stroke Callies crank. 10k miles on the LS1 383 and no oil burning. 3k miles on 416 LS and no oil burning.

y pipe and cat back - A pair of electric cut outs off the headers will get by but exhaust through Y pipe to catback will hurt performance. I think a good true dual 3 inch x pipe set up will be worth it. If the car is lowered the Hooker BlackHeart works pretty well on my lowered TA. It's probably restrictive around ~600 flywheel hp or ~500 whp. The BlackHeart is decent probably benefit from cutouts after the x pipe.

the ls2 block be overbored safely? - machine shop said my LS2 block needed .010 over for clean up and it could be honed a couple of times for rebuilds. At least .020 is doable.

1. Have a low usable torque range - 400 wtq at 2,800 rpm is easy to do. I like that. Some will say it's too much and not use able.

2. Max shifting rpm of 6700 to 7k - the Fast 102 is always popular and basic porting for Vengeance Racing or similar can help a bit. A radius rod mod LS3 Rick Crawford can flow almost as much air and might work good for the budget and ~6700 rpm shift point. Definitely more budget friendly than an LSXR but not as rpm friendly.

3. Be a solid and reliable piece that can take some abuse without hesitation on track Scoggin Dickey does a budget friendly LS3 427 short block that has a good reputation.

4. Be 91 octane friendly - I'd get a set of LS3 take off heads from the market place for $525 and send to Reher-Morrison and have RM port them. Darin Morgan can set them up to be 91 octane friendly. Including the cost your cores you will have less than $1,600 in a sweet quality set of ported LS3's with quality Manley valve springs etc. Darin can so help with cam selection to reach your goals.
​​​​​​
My flow testing suggest these heads can support 720+ flywheel horsepower with the stock LS3 valves. Darin's RM heads and cam package was tailored to hit my goals perfectly with a fun daily driver build.

taman86

iTrader: (19)

Well I've been using my company's time to do a lot of google searching today looking into what everyone has pointed out. Btw, thank you all for the input, i love learning off of the veterans who have had the trial and error.

so based on the recommendations for pistons i searched through the inventory of several site sponsors and it appears that wisecos are indeed the business for pistons, i understand now why blackbird calls them trick pieces. I am leaning more towards the 4.1/.125" strokes to help take advantage of the ls3 head flow and do a slight over bore to help unshroud the valves.

i was looking into tsp and they appear to have a very budget friendly stroker kit using the wiseco pistons and their signature cranks and h beam rods. But according to their website their cranks can only be used with acl bearings? I've never heard of them before does anybody have any experience with that brand. I was hoping to use more performance oriented coated bearings for reduced friction but those can only be run on other cranks listed. Also, what would be the better route to go for rods? Use the tsp h beams? Use callies h beams or use i beams?

Blackbird- i know you run the rh heads and I've been following your flow testing thread since its inception so i saw that they flow phenomenal with the fast. But on a relatively small bore wouldnt those heads be way overkill considering that the consensus says the gmpp ls3 heads are over kill for a 6.0? But aside from that how much better are they worth considering the gmpp ls3 heads and those are supposed to be an upgrade on a stock cube ls3?

but seeing as im trying stay on a moderate budget, hopefully 3k all in cost after i recoupe some money from my ls1 stuff, i think I'm gonna stick with the stock ls3 setup. I have seen the rick crawford mod do very well, i may still look into that.

tech@WS6store

iTrader: (2)

Acl has been in the bearing business for a long time. some racers only use them.

A 4.100+ stroke is a waste on a small bore.

99 Black Bird T/A

iTrader: (4)

Taman - cool it's nice to know the flow test gets followed
Trying to set up a time to test a Fast LSX 92mm for the next intake test.

Darin @ RM would be in the best position to know the most cost effective approach. It might be a stock LS3 head with a revised valve job & spring kit instead of the CNC'd head. I also think Darin would be one of the best for spec'ing a custom cam for the LS3 heads and 4.0 ish bore. My guess is with the big LS3 intake runners the cam intake duration might be a few degrees lower on an LS2 bore with LS3 heads than on the typical 4.065 bore LS3.

Might be worth a call to RM.

FWIW - I like the idea of Ls3 heads & intake on an LS2. Seems like a good way to make hp and avoid a $1,000 fast intake

I think cost wise the GMPP LS3's & used cores with RM LS3,'s will be about the same price when all is said and done. The GMPP springs are limited to about .550 lift if I recall correctly. They also have bigger intake runners than the RM heads but down flow as well and would likely loose velocity.

Some LS2 blocks can go .030 over so a 4.030 bore might be possible and would help unshroud the valves.

G Atsma

I think a nice set of bowl-blended OEM LS3 heads with a good multi-angle valve job would surprise more than a few well-known CNC LS3 heads. Flow would improve all the way up and down instead of just the mid and highest lifts. I've noticed the TSP CNC LS3 heads BARELY increase the intake port size and flow REALLY well. I wonder if indeed they are done as I describe above?

KW Baraka

iTrader: (7)

I have a set of these that'll be for sale pretty soon.....with Comp Ultra Pro-magnum Rockers and a stock LS3 intake, too.

Jus' sayin'.

KW

G Atsma

Can you tell whether the ports are machined very much? Or is it mostly a good valve job and bowl blend?

taman86

iTrader: (19)

Are there certain years or casting numbers for the blocks? Mine came out of a tbss but it's been years that I've been holding onto this block

why is it a waste to go that long of a stroke. Several companies offer them? Or is it to sell to retards like me that don't know anything but think they're getting the best?