newschool72

iTrader: (12)

Eventually, i plan to throw some forged pistons and rods in my LS3 shortblock and im interested in what most people are liking as far as compression on a street pumpgas engine running an air to air and 50/50 water /meth.
right now, im running the SBE with 72cc 317 heads and ricer worthy .098 MLS head gaskets. Static comes in at 9.2 and ive had zero issues at 14psi and 15* .
reason i ask is i really hate killing the quench with those gaskets and the JE pistons that are going in later on have -5cc valve reliefs the stock pistons dont have. With stock LS9 gaskets, my compression would come in around 10.1.
Whats the concensus these days on pump gas, water/meth and moderate boost. How much would the .8-.9 higher compression tighten my tune window ? Id really like to get out of ricer ed with my engine, but since its worked great with the SBE setup, i wont hesitate to run the fat gaskets if the extra compression is gonna cause tuning grief.
what do the turbo ls gurus say ?

customblackbird

iTrader: (2)

I run a 5.3 stock deck and light cleanup on some 862 heads with stock GM LS1 MLS gaskets. Stock everything except springs and pushrods and a custom blower cam. I run 15psi daily via a billet 78/75 on the cheapest 93 pump I get my hands on with wiper fluid at 750cc/min and a eBay A2A. I run about 18* at 15psi and the stock compression is 9.5:1 which is a tad higher than you. I think you could run more timing for sure which will pick u up a bit of power and at 15psi you could easily be 18-20* as the 50/50 really helps with detonation but sucks alittle power as it displaces air and fuel.

most here will tell you that you could bump compression and run straight meth for optimal results. Or you could leave it as is and just bump the timing abit as your compression is alittle lower and safer. You could also rip those 317s off and put on some 862 or 706 heads and pick up a bunch of power. Richard holdender didn’t a test recently
with a 5.3 with 706 and 317 heads and the 317s made a lot less power and made more boost (restriction), 706 heads made like 30hp and 40ftlbs more at .5psi less boost. If boost was increased on the 706 heads to match the 317 the power different would have been even greater.

best option would be stock 5.3 heads, straight meth and bump the timing and boost.

EDIT: forgot I also run the TR6 plugs. I thought about running the bR7 but I’ve heard of issues running them out of boost.

ddnspider

iTrader: (26)

Detoxx on here made just shy of 1000whp with a SBE ls3.....unless you have 4 digits goals or other issues leave the motor alone and turn the boost up with the 50/50. Let the boost do the work over adding a bunch of timing. And read the plugs to see when you're reaching a limit. I assume you're running a nonprojected BR7 or something colder than the TR6s everyone runs?

Detoxx03

iTrader: (14)

I saw the thrash and was gonna post this. Agree 100%.

newschool72

iTrader: (12)

Yea, bre7s. Last time i looked, it was uber safe. I have a set of truck manifold copies made of 321SS that are gonna make plug checking much easier in the future. Right now im running CXracing fbody turbo headers and the plugs are a nightmare to pull.

newschool72

iTrader: (12)

i hand ported the 317s using a vengence racing article on how to make them flow. I CCed them when i finished and they are at 220ccs now. Exhaust is 84ccs. Combistion chambers are 72ccs. I pulled and sold the ls3 heads that came on the crate motor to help finance the turbo setup.

ddnspider

iTrader: (26)

Can you get stock manifolds in there? Super strong, easy plug access, and keeps all the heat in the hotside.

newschool72

iTrader: (12)

passenger side is super tight and i would have to cut the pipe flange off and change thr angle to clear. Im not comfortable welding cast and its very difficult for me to redo leaky work . Its all i can do to do things once and i can weld stainless to stainless without having to worry about it not "taking". I do agree a heavy cast manifold is better for spool though. Thanks for the input regardless. Much appreciated.

ddnspider

iTrader: (26)

NP, hope you get it sorted. I've only ever used shorty/stock manifolds so never had plug trouble. Some of these kits make plug changes brutal. In my opinion if you have to remove the manifold to do a plug swap, it's not a well done kit lol.

newschool72

iTrader: (12)

can i get an AMEN, brother !

customblackbird

iTrader: (2)

The 317s flow alot more than stock 5.3 heads already. The flow isn't a huge concern when its boosted. With a 5.3 SBE the stock 5.3 heads will make more power than the 317s even if you ported them and hit it with your purse. The smaller chamber, and smaller ports help flow with the smaller bore of the 5.3, the 317 heads are a missmatch honestly and your compression is not low enough to warrant the swap give the loss of compression and airflow velocity. Watch this video...

customblackbird

iTrader: (2)

Yea I can't pull my plugs from the top with my CX racing turbo headers and I had to make long under engine plug wires with 90 degree boots to clear the headers and allow me to keep my coils on the valve covers. My work around is lifting the car and pulling them from the bottom which adds maybe 20 min to changes. But I agree, I miss the plug access and stock style plug wires that I had with my racing innovations ebay LT headers. I don't pull the plugs often tho... or I haven't in the last year or so.

ddnspider

iTrader: (26)

That sounds miserable....but at least its got a turbo on it

SLOW SEDAN

iTrader: (13)

Doing plugs from the bottom really isn't that bad, I've had a few vehicles that were like that. It's not like relocated coils are hard to do either, actually makes the engine look at lot cleaner.

ddnspider

iTrader: (26)

I'd rather not have to jack the car up for a plug change, especially when checking them at the track....

SLOW SEDAN

iTrader: (13)

People say that, but all my tubular manifold turbo kits spooled faster then my stock manifold kits and were a lot lighter. Kinda like people say ohh a 2" crossover will spool better, but for some reason a 2.5 works perfectly fine.

SLOW SEDAN

iTrader: (13)

Everyone has a preference, to me its easier laying on the ground and working up then bending the old back and leaning over a fender. Have to jack up cars to adjust shift linkages, wastegates, change oil/trans fluid, replace axles, and whatever else comes up anyways, should probably have a jack handy.

ddnspider

iTrader: (26)

Then your stock manifolds sucked. Plenty of data out there proving that cast stock manifolds hold it heat and decrease spool compared to tubular.

SLOW SEDAN

iTrader: (13)

Have a link to this back to back test from stock manifolds to coated and wrapped set of tubular manifolds? I believe it depends on multiple factors, if stock manifolds were the end all of turbo performance you would see a lot more race cars with them, but you don't.

ddnspider

iTrader: (26)

Heard of the Ohio Boys? Ever seen back to back testing on rear mount turbo's where they went from tubular long tubes to stock manifolds? Zombie on here did it. I don't need a specific link when the physics and info is obvious that cast manifolds simply retain more heat instead of dissipating it.......I thought you didn't do racecar stuff. Everything is a street car Racecars also care about weight and not everyone can fit stock manifolds.