fbodyfreakls1

Long story short I have a 84 z28 I been restoring and am trying to get an engine together, my ls1 block has rust putting that will require new sleeves. $2150 for race engine development to do so. Was going to mid sleeve this block anyways but RED informed me that dartin has restricted sales of mid sleeves to billet blocks. And even if he could get them I would have to run motor plates, not interested. So I started shopping for blocks and after some frustration I started looking at short blocks. I was really planning to build this engine but this isn’t the first engine snag I have hit and I’m starting to become over it. So I was looking at a 415 short block ls3, pricing was fair and all but can’t find one with pistons to achieve the compression ratio I am after for this going to be corn fed beast. Even with milling down a set of heads that would fit the bill I can’t even get to 14:1, 13.8:1 was best I could calculate. I haven’t asked but I’m sure to have them build me one with a bigger dome piston will cost me some extra bucks and then makes it not look so appealing. So I went looking at sbc short blocks just cuz, found I can get a 434 short block for even cheaper with pistons good for 15.56:1 on a 65cc chamber, now we’re talking. Started doing some research and both engines are capable of the 700+ crank hp I am after to send my car into the single digits. The sbc combo is cheaper to put together and more cubes for less money. The ls3 based 415 have better head selection as far as flow numbers but flow isn’t the whole picture. The 434 I would run afr 245s on and their intake manifold the ls3 415 would have a top end combo apexes out by tony at mamo. What would you guys do in my shoes? Thanks

Orr89RocZ

iTrader: (20)

Well you dont need 14:1+ to make 700 on either deal

and done right its possible to do that on ls3 heads, slightly ported with proper valve job but it would need a good intake, not a fast or oem type.

May do that on a ls3 factory block. I know 600’s is easily doable on pump gas.. Sbc will need atleast a dart shp block. Adds cost and weight in iron

sbc will need real good heads. Afr 245’s could do it but once again needs good intake, a well ported single plane. I would talk to chad speier racing heads for a top end package deal. I would look at his 245 heads or send him your afr 245’s to look at and get a manifold figured out for it. He’s had 427-440 type sbc deals make over 800 hp with 23 deg heads...

fbodyfreakls1

I know I need 700 to get in the single digits but anything more would be amazing. Running e85 and want to take advantage of opportunity to run higher compression with the fuel.

Shortly after I got the car I decided to go ls, had a 5,3 block and a lsa blower, gm efi harness computer etc, decided I wanted to go carb so I could tune it and knew the 5.3 wouldn't make the power I wanted N/A, sold the short block and bought a locked up 98 ls1, had 63k on it but sat out side, beat the pistons out of it and gave it a ball hone job, found it needed sleeves, was going to build a MID sleeved 443 until Steve at RED talked me out of the MIDs and I posted the ls1 for sale. thought I had a good ls7 lined up for cheap that needed sleeved but Steve also steered me away from it due to where the cracks were it its sleeves. still trying to sell ls1 block and weighing my options for what I want to do now. Cant seem to find any good deals on used stock blocks, so I started looking at short blocks. LS3 blocks are to expensive to buy new bare and LS2 blocks cant bore out big enough for the cubes, plus it just seems frivolous to buy a $1500 block and **** it straight to RED for another $2150 in darton dry sleeves when I can get a blue printed, ready to rock 415 stroker short block for $5000. I'm no rich man but I want to built it once and build it right and I want to get the most for my dollar. The 434 is a dart shp block and is a blue printed ready to rock short block for $4400. The 434 is looking like the hot ticket, afr 245s are $2750 and the ls3 afr 260s are $2600. Shafiroff offers a 434 sbc with afr 227s that are $1825 that makes 710hp at 6600rpm with 14:1 compression. bump comp up tp 15 and change and run e85 with a 245 head (if that head isn't too much, would need to talk to afr) and give it a few more rpm sure it would respond well. Same goes for the ls3 stroker, 12* head over the sbc afr being 23*, flow numbers are better, not that that is the whole story. I know I can get there with either engine, shp block vs stock block, 434ci vs 415ci, ls vs sbc, cast iron vs aluminum. id like the ls3 block for the weight savings for sure. just not sure which way I want to go at this point. I have a lt1 t56 that will go behind either, I chose a lt trans due to wanting to run an external slave cylinder. had my fair share of issues with the internal slave of the ls breed nd don't like how much of a pain in the *** they are to bleed, nor a long braided hose hanging some where, pulling trans to service it or a leak getting to the clutch. I'm sure 5 bell housing bolts will get the job done.


Thanks for chiming in, I'm in my head a little at this point, finances are lining up and I thought I had a plan but it all fell through, I have a hard time making decisions because I over think and analyze everything. I would rather go LS anything but I just want to be happy with the car at the end of the day, I want it to run 9s on motor, drive it home and maybe throw some N2O at it if I ever feel the need to go faster.

Orr89RocZ

iTrader: (20)

Well if you could get into a ls3 block you dont need to sleeve it. Simple molnar 4” crank and basic 4.070 bore will do it but might want custom pistons for this. Need heads first to mold chambers so the dome can be made to match. In order to get 14+ comp. i personally wouldnt go over 14 with e85.

Either way you need to talk to an engine builder or head guy that can get you an intake to match. Just bolting on some out the box deal is gonna limit you esp if you want to be carbed

fbodyfreakls1

I have been in touch with Tony Mamo regarding a LS engine, I would have no clue who to talk to for induction on a SBC, havnt messed with a SBC since I had my 87 iroc drag car over ten years ago. I bought a 99 z28 and have been all for ls power since. I even swapped my 99 k2500 suburban with a healthy comp flat top 5.3 that I built. A new ls3 block is around $2200, which makes a pre-assembled short block look great $$$ wise. I did really want to build this engine but I may swallow my pride on this one. The cnc-motorsports short block I'm looking at has a 3.1cc dome piston, with a quench of .035 and a 62cc head that's 13.84:1. if 14ish is the limit on e85 then that would work out perfect. The short block is a little more money but the heads are cheaper, well if your going AFR, I plan on giving Tony my business on that venture so that would be a few more dollars but well worth it. I have been hoping a worked over vic jr intake would feed the engine so I can keep my stock SMC z28 hood, did see a 700ish hp engine some where on the internet using a gm single plain so I think that would get me there, ill have to see what Tony says. I still have the original 5.0HO air cleaner set up and thought it would be cool to put on the car when I take it to car shows etc.

if 14ish is the limit then I think I have made my mind up, the 415 will get there compression wise and the short block is well priced. ill have to talk to cnc before I order about piston ring gap for the possibility of nitrous so they can assemble accordingly.

Orr89RocZ

iTrader: (20)

It may not be the limit but its getting up there and imo, the gains from 15:1 vs 14:1 dont really start adding up considering you lose some piston to valve i believe depending on the pockets but mainly disrupt flame front travel as the dome shields the spark plug.

i just wouldnt design around compression, get it to flow air you need, but 12.5-14:1 is fine

I would seriously talk to chad speier for heads and intake for sbc. Hes done what you want.
Thats pretty basic 427 setup at 13:1 lol. The heads and intake plus good solid roller cam is key
http://www.cpmotorworks.com/Engines/...2/Default.aspx

https://speierracingheads.com/index.html

fbodyfreakls1

Thanks Orr89RocZ, ill get my ducks in a row.