Go Back   LS1TECH > LS1-LS2-LS3-LS6-LS7 PERFORMANCE > Advanced Engineering Tech
Sign in using an external account
Register Forgot Password?
Register iTraderTimeslips Photos Members Search Today's Posts Mark Forums Read Used CarsVendor Directory
Search

Advanced Engineering Tech
For the more hardcore LS1TECH residents
Sponsored by
Whipple Super Chargers

Welcome to LS1Tech.com!
Welcome to LS1Tech.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join LS1Tech.com today!


Reply
 
Thread Tools Search this Thread
Old 01-13-2004, 07:03 PM   #1
Brought out of retirement Super Moderator
Garage is empty, add now
 
Reckless's Avatar
 
Trader Rating: 7
Join Date: Nov 2001
Location: Waco, TX
Posts: 9,793
Send a message via MSN to Reckless
Default Why "zero deck" custom pistons?

I know there is a good reason, and I may order my next set this way again. Does it affect quench or what? What is the specific reason to zero deck instead of using standard "out of the hole" pistons?
__________________
Todd B.
2010 Cadillac CTS-V
Former cars:
2000 NHRA Edition Formula, A4, Hard Top
2000 Trans Am WS6
1998 Formula WS6 1LE

Reckless is offline   Reply With Quote
Old 01-13-2004, 07:10 PM   #2
TECH Addict
Garage is empty, add now
 
LS1derfull's Avatar
 
Trader Rating: 0
Join Date: Dec 2001
Location: new england
Posts: 2,298
Default

Quote:
Originally Posted by Reckless
I know there is a good reason, and I may order my next set this way again. Does it affect quench or what? What is the specific reason to zero deck instead of using standard "out of the hole" pistons?
The only reason i can think of for zero deck is for rod stretch clearance. It will affect your quench in a negative way, you want tightest quench possible to prevent detonation and maximize combustion efficiency.
__________________
2001 Camaro Z28 m6 11.88 @119.42 mph 1.76 60 ft. 7.62 @94.11 mph! in 1/8 all Granny shifts at 3506 lbs. Dyno : 402 RWHP and 391 FT.LBS Current mods: Heads stage2,ported LS6 intake, ported TB and Maf by LS1derfull, MMS 220*cam,LS1 Edit by SLOWHAWK and TRACER X! Hooker LT and off road Y pipe,4.10 gears (still stock rear) Other car: 1968 Chevy II small block N/A 9.8@137mph 775 est.flywheel hp.
"F-Body may be gone, but this one is not, and it only takes ONE to ruin YOUR whole day !"
LS1derfull is offline   Reply With Quote
Old 01-13-2004, 09:22 PM   #3
TECH Fanatic
Garage is empty, add now
 
strokedls1's Avatar
 
Trader Rating: 1
Join Date: Nov 2002
Location: Venice, Ca
Posts: 1,829
Default

I did zero deck pistons to keep the the rings a little lower so they are run at a little lower heat. The quench can be set by the head gasket thickness. This can also give you room to deck the block in the future. Zero deck was also recommended by the sales man at JE.
strokedls1 is offline   Reply With Quote
Old 01-14-2004, 02:53 AM   #4
TECH Addict
Garage is empty, add now
 
Grimes's Avatar
 
Trader Rating: 3
Join Date: Mar 2003
Location: Northern NJ
Posts: 2,638
Default

Supposedly running a zero deck height offers better quench and helps promotes combustion/prevents detonation. I guess if people are selling zero deck pistons this is assuming that you have a standard deck block.

When I have heard of ppl running zero deck in old school SBC's, I usually see them put the rotating assembly in, measuring how far the pistons are below deck surface w/ dial gauge, then decking the block that distance.
Grimes is offline   Reply With Quote
Old 01-14-2004, 07:04 AM   #5
Brought out of retirement Super Moderator
Garage is empty, add now
 
Reckless's Avatar
 
Trader Rating: 7
Join Date: Nov 2001
Location: Waco, TX
Posts: 9,793
Send a message via MSN to Reckless
Default

I will actually have the block checked before ordering. If the deck needs milling, then I will order the pistons for that application. This will be a 15psi 408 motor, so the pistons will already have about a 28cc dish. I would think this would affect quench more than the deck height.
__________________
Todd B.
2010 Cadillac CTS-V
Former cars:
2000 NHRA Edition Formula, A4, Hard Top
2000 Trans Am WS6
1998 Formula WS6 1LE

Reckless is offline   Reply With Quote
Old 01-14-2004, 07:49 AM   #6
TECH Addict
Garage is empty, add now
 
NoGo's Avatar
 
Trader Rating: 2
Join Date: Jan 2002
Location: Rhode Island
Posts: 2,622
Default

I agree with LS1derfull.

The only reason to run zero or negative deck is to compensate for conrod stretch if you plan on running HIGH rpm or aluminum rods. If you are going to be running regular stock-bushed or forged steel, then I would run the stock rise or even more.

Squish is not a factor, it is THEE factor when you talking of building a detonation free motor. Squish is the biggest contributing factor for detonation. You should always try to maintain at a minimum the stock squish. Piston rise on a stock LS1 is 6 thou.
On a FI build it is a good idea to run even more of a rise because of the gaskets that you have to run in a FI setup (they usually sit the heads higher off the deck).

I run a 10 rise on my pistons. I have had very good luck with this setup (and others that we have done) and have NO detonation problems on pump gas.

D1 on a 383 all-bore at ~8 psi. Total timing advance is 26 deg at WOT (this is alot for a FI motor). Most other builds (home grown or whomever) I have to back the timing down to 19-22 deg to avoid detonation.

Just my input.

Good Luck
__________________
-Kevin

383 Supercharged '00 TA
699 HP
676 Tq
NoGo is offline   Reply With Quote
Old 01-14-2004, 08:23 AM   #7
Brought out of retirement Super Moderator
Garage is empty, add now
 
Reckless's Avatar
 
Trader Rating: 7
Join Date: Nov 2001
Location: Waco, TX
Posts: 9,793
Send a message via MSN to Reckless
Default

Thanks Kevin...good input
__________________
Todd B.
2010 Cadillac CTS-V
Former cars:
2000 NHRA Edition Formula, A4, Hard Top
2000 Trans Am WS6
1998 Formula WS6 1LE

Reckless is offline   Reply With Quote
Old 01-15-2004, 04:35 AM   #8
TECH Fanatic
Garage is empty, add now
 
z-ya's Avatar
 
Trader Rating: 1
Join Date: Jan 2003
Location: minneapolis,mn
Posts: 1,096
Default

I have found that small block chevs start contacting the head at about.027 squish
with steel rods.Does anyone know if that number is similar for ls1 engines?
__________________
2001 z/28 2004r,moser 12 bolt 4.30,
3 1/2 ds,1350 ujoints,hals,air bag,centerline convopros,M&H 275x60x15 muscle car drags,line lock,edelbrock coated race victors,5.3 ported heads, bowler cam,magnaflow catback,ported fast90,nw tb,racetroics fp and hot wire,42lb injectors march pulley,160 stat,2step,yank crossmember,n20
4130 lca's,phb,sfc,stb,hp tuners,lm1,arctic wht,
z-ya is offline   Reply With Quote
Old 01-15-2004, 08:27 AM   #9
TECH Addict
Garage is empty, add now
 
LOnSLO's Avatar
 
Trader Rating: 15
Join Date: Sep 2002
Location: Gainesville, GA
Posts: 2,537
Default

I am running .020 out of the hole with my custom Diamonds. I am also using a .062" copper gasket, which will put quench height at .042 theoretically. I expect to lose 4 or 5 due to rod stretch however. Minimum quench height in my book is about .040, so it will be close.
__________________
2002 SS 6 Speed
Mods
LOnSLO is offline   Reply With Quote
Old 01-15-2004, 04:18 PM   #10
SSU Moderator
Garage is empty, add now
 
RyanJ's Avatar
 
Trader Rating: 0
Join Date: Nov 2001
Location: Allen, TX
Posts: 4,858
Send a message via AIM to RyanJ
Default

Here's my question. LOnSLO, why go .020 out and have a .062 HG when you can go .006 out and use a .048 gasket (which is probably a stocked item)? Something with the compression height of the piston.
RyanJ is offline   Reply With Quote
Old 01-15-2004, 04:32 PM   #11
TECH Fanatic
Garage is empty, add now
 
strokedls1's Avatar
 
Trader Rating: 1
Join Date: Nov 2002
Location: Venice, Ca
Posts: 1,829
Default

I did 0 deck which is really about 1-2 thousandths out with a .041 head gasket and have zero knock problems with a 11.2 compression. I run 28.5 timing with 0 knock and don't find it necessary to run more, with cali 91 octane. Running a little more out of the bore is supposed to give you snappier throttle response.
strokedls1 is offline   Reply With Quote
Old 01-16-2004, 10:04 AM   #12
TECH Addict
Garage is empty, add now
 
LOnSLO's Avatar
 
Trader Rating: 15
Join Date: Sep 2002
Location: Gainesville, GA
Posts: 2,537
Default

Quote:
Originally Posted by RyanJ
Here's my question. LOnSLO, why go .020 out and have a .062 HG when you can go .006 out and use a .048 gasket (which is probably a stocked item)? Something with the compression height of the piston.
Exactly, they are 12.25 compression pistons. I wanted to avoid having to use a domed piston, so we decided to run them out of the hole a little more. They were built with a .062" gasket in mind. Also, this is a 4" stroke motor.
__________________
2002 SS 6 Speed
Mods
LOnSLO is offline   Reply With Quote
Old 01-16-2004, 11:58 AM   #13
TECH Veteran
Garage is empty, add now
 
2001CamaroGuy's Avatar
 
Trader Rating: 5
Join Date: Feb 2002
Location: Fountain Hills, AZ USA
Posts: 4,750
Default

I'm doing 0.001" out with a 0.041" gasket which should give between 0.040" and 0.035" depending on how much the rods stretch
__________________
Chris

2003 Maldives Blue Metallic BMW Z4
- 2880lbs (wet weight)
- E46 M3 diff/rear suspension swap
- 427 LS7/T56 swap (in process)
2001CamaroGuy is offline   Reply With Quote
Old 01-16-2004, 01:47 PM   #14
TECH Senior Member
Garage is empty, add now
 
Brains's Avatar
 
Trader Rating: 7
Join Date: Jan 2002
Location: Katy, TX
Posts: 12,760
Default

I run .010 out with a .041 (Fel Pro 1041) gasket ... With the smaller cam (224/224) it had more throttle response than I could realistically use on the street. With the bigger cam (238/240) I have an off-idle stumble that's driving me crazy
__________________
This space for rent

LS1 Mustang Project Website

The new toy: 2007 Dodge Charger SRT8
http://brains.ls1tech.com/ChargerSig.jpg
Brains is offline   Reply With Quote
Old 01-16-2004, 05:28 PM   #15
TECH Addict
Garage is empty, add now
 
LS1derfull's Avatar
 
Trader Rating: 0
Join Date: Dec 2001
Location: new england
Posts: 2,298
Default

Quote:
Originally Posted by Brains
I run .010 out with a .041 (Fel Pro 1041) gasket ... With the smaller cam (224/224) it had more throttle response than I could realistically use on the street. With the bigger cam (238/240) I have an off-idle stumble that's driving me crazy
Try more timing and play with A/F tuning, if you have around 11 to 1 compression you should be able to run that cam w/out stumble.
__________________
2001 Camaro Z28 m6 11.88 @119.42 mph 1.76 60 ft. 7.62 @94.11 mph! in 1/8 all Granny shifts at 3506 lbs. Dyno : 402 RWHP and 391 FT.LBS Current mods: Heads stage2,ported LS6 intake, ported TB and Maf by LS1derfull, MMS 220*cam,LS1 Edit by SLOWHAWK and TRACER X! Hooker LT and off road Y pipe,4.10 gears (still stock rear) Other car: 1968 Chevy II small block N/A 9.8@137mph 775 est.flywheel hp.
"F-Body may be gone, but this one is not, and it only takes ONE to ruin YOUR whole day !"
LS1derfull is offline   Reply With Quote
Old 01-16-2004, 07:00 PM   #16
Launching!
Garage is empty, add now
 
Trader Rating: 0
Join Date: Dec 2003
Location: Portland OR
Posts: 251
Default Quench

From z-ya:

"I have found that small block chevs start contacting the head at about.027 squish with steel rods.Does anyone know if that number is similar for ls1 engines?"

I posted in another thread on this topic, and got no response from the tuner community. But, most of the parameters which control piston/head contact in an SBC are similar in an LS1 - bearing clearances, stroke (and therefore piston speed), rod cross section, rod length, piston weight. The only differences I could postulate are the block material - aluminum has greater thermal expansion than iron, and *might* tend to increase the deck height more in a warm engine - and the piston material, which is hypereutectic aluminum in a stock engine and therefore has lower thermal expansion than the forged pistons used in most aftermarket SBC applications.

In any case, I wouldn't bet on being able to run much tighter clearances

To the general topic of the post, I think the zero deck vs. out of hole piston doesn't matter much as long as quench clearance is minimized by tuning gasket thickness - as several posts have pointed out. Although I don't know for sure, I suspect the reason for the out-of-hole design of the factory piston has to do with emissions reduction. Modern combustion chambers are so efficient that most of the unburned fuel (HC emissions) comes from crevices where fuel/air hides out away from the direct flame front - valve clearance pockets, valve/seat crevice, even plug threads. Anyway, the biggest crevice is the piston/cylinder wall gap, with the compression ring as the floor of the crevice. By popping the piston out of the bore a bit at TDC, some of that fuel in the crevice is expelled, while only exposing the ring to extra combustion heat for a brief period at TDC. Very clever, actually. BTW, crevice volume also explains the OEM fondness for hypereutectic pistons - they expand less under heat, and therefore allow closer piston/cylinder wall clearance. And, the pure flat-top piston with no valve clearance pockets.
__________________
71 Camaro LS1, AFR 205s, Comp 224/228, FAST 90/90, 453 RWHP, Baer brakes, Hotchkis suspension.

67 Camaro convert, 548 Aluminum BB, 618 RWHP, Super Rod cover car.
71CamaroLS1 is offline   Reply With Quote
Old 01-16-2004, 09:51 PM   #17
TECH Addict
Garage is empty, add now
 
Grimes's Avatar
 
Trader Rating: 3
Join Date: Mar 2003
Location: Northern NJ
Posts: 2,638
Default

True. Crevice volume is also why emissions are a problem on larger bore motors.
Grimes is offline   Reply With Quote
Old 10-19-2005, 09:09 AM   #18
LS1Tech Co-Founder
Garage is empty, add now
 
Nine Ball's Avatar
 
Trader Rating: 38
Join Date: Nov 2001
Location: Houston, TX
Posts: 33,001
Default

good info!
__________________
Co-Founder, LS1Tech.com & PlanetLSX.com
Online Garage: www.fquick.com/NineBall
Nine Ball is offline   Reply With Quote
Old 10-19-2005, 09:25 PM   #19
Launching!
Garage is empty, add now
 
Trader Rating: 8
Join Date: Dec 2004
Location: GI, NE
Posts: 287
Send a message via MSN to mattr228
Default

perhaps companies who produce rods take in to account "rod stretch" when designing a certain length rod

holy old thread batman!...... good forum tony!
__________________

mattr228 is offline   Reply With Quote
Old 10-19-2005, 09:43 PM   #20
Launching!
Garage is empty, add now
 
Trader Rating: 0
Join Date: Nov 2003
Posts: 210
Default

The zero deck is to keep the compression at a reasonable level with the 408 cubic inches of displacement. If you run the pistons .008 out of the hole and use a .040 gasket on a 408 I am pretty sure the compression will be too high.
Zippinzee is offline   Reply With Quote
Old 10-19-2005, 09:43 PM
LS1Tech
Pontiac Firebird




Paid Advertisement
Reply

Tags
397178, 53, cam, chevrolet, clearance, custom, cylinder, deck, good, liter, piston, pistons, quench, racing, road


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off



All times are GMT -5. The time now is 05:10 PM.


Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.5.2
Advertising - Terms of Service - Privacy Statement - JOBS
Emails & Contact Details