427 LT5 Build 2 underway - ZR-1 Net Registry Forums

tpepmeie · 04-25-2015

Here we go, guys. Thought I would make a new thread to document build 2. The target is 800 bhp, @ 7400 rpm. Some upgrades from the previous version (700 bhp/6900):

New larger inlet valves (41.5mm v. 39.5mm)
Higher compression ratio
Billet aluminum mono blade throttle body
New cams...maybe

Here are two links to other discussions about Build II.
http://www.zr1.net/forum/showthread.php?t=23894
http://www.zr1.net/forum/showthread.php?t=23537

I was never really happy with the ring seal on the first build, both from a blow-by and oil control perspective. So, we're now using new pistons, a different bore finish, and new rings. These pistons (430g) are a bit heavier than the featherweight CP forgings I used in build 1, so the crankshaft will need rebalanced. The intention is to get better stability of the piston in the bore.

Ross Custom billet pistons. 14:1 / Flat Top / .140" deep valve pockets made from a mold of my combustion chamber. These valve pockets will accommodate more than .550" valve lift if I decide to go there...

.043/.043/3mm Total Seal rings

XfireZ51 · 04-25-2015

Groundbreaking stuff Todd. You're one of the people we should celebrate for advancing the ball!

FU · 04-25-2015

Gas ported pistons

nice option.

Blue Flame Restorations · 04-25-2015

What bore finish are you planning to use?

A26B · 04-25-2015

I've seen the groove between the compression rings on Mahle LT5 pistons before. Can you elaborate on yours?

tpepmeie · 04-25-2015

Quote:

Originally Posted by Blue Flame Restorations

What bore finish are you planning to use?

Whatever Total Seal recommends

. Seriously, though, I think the finish hone is 280-320, with a specific cross hatch angle. Keith Jones at Total Seal is the guy.

tpepmeie · 04-25-2015

Quote:

Originally Posted by A26B

I've seen the groove between the compression rings on Mahle LT5 pistons before. Can you elaborate on yours?

Jerry,
most all of the high end pistons have this. I believe the theory is to provide more volume for the gas pressure that escapes past the top ring. The groove helps relieve that instead of compromising the ring seal in the land. At least that's the way I understand it.

tpepmeie · 04-27-2015

I added a couple of links to the original post, just to keep it all together.

Some other upgrades for Build II:

Custom main bearing studs
ARP head studs
Cometic MLS head gasket
Custom heavy duty secondary cam chains ()
improved crankcase ventilation
upsized fuel delivery system, incl. new rails & adj regulator
alpha-n fuel calibration, fully mapped on engine dyno
RAM dual disc clutch

That's all I can think of right now. This should be fun.

USAFPILOT · 05-04-2015

Is this a second engine or a rebuild of the 1st 427?

bradley · 05-04-2015

could you share what your doing to improve the crankcase vent system ??????

04-25-2015	#1
tpepmeie Join Date: Aug 2005 Location: Fishers, IN Posts: 815	427 LT5 Build 2 underway Here we go, guys. Thought I would make a new thread to document build 2. The target is 800 bhp, @ 7400 rpm. Some upgrades from the previous version (700 bhp/6900): New larger inlet valves (41.5mm v. 39.5mm) Higher compression ratio Billet aluminum mono blade throttle body New cams...maybe Here are two links to other discussions about Build II. http://www.zr1.net/forum/showthread.php?t=23894 http://www.zr1.net/forum/showthread.php?t=23537 I was never really happy with the ring seal on the first build, both from a blow-by and oil control perspective. So, we're now using new pistons, a different bore finish, and new rings. These pistons (430g) are a bit heavier than the featherweight CP forgings I used in build 1, so the crankshaft will need rebalanced. The intention is to get better stability of the piston in the bore. Ross Custom billet pistons. 14:1 / Flat Top / .140" deep valve pockets made from a mold of my combustion chamber. These valve pockets will accommodate more than .550" valve lift if I decide to go there... .043/.043/3mm Total Seal rings Last edited by tpepmeie; 04-27-2015 at 09:01 PM. Reason: resize pics; add links

04-25-2015	#2
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,704	Re: 427 LT5 Build 2 underway Groundbreaking stuff Todd. You're one of the people we should celebrate for advancing the ball! __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

04-25-2015	#3
FU Join Date: Mar 2004 Location: Found Member Posts: 4,346	Re: 427 LT5 Build 2 underway Gas ported pistons nice option. __________________ Frank Urbo. NCM Lifetime member # 982 Registry Founding # 237

04-25-2015	#4
Blue Flame Restorations Join Date: Feb 2010 Location: Pendleton, IN Posts: 3,904	Re: 427 LT5 Build 2 underway What bore finish are you planning to use? __________________ 1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project

04-25-2015	#5
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,393	Re: 427 LT5 Build 2 underway I've seen the groove between the compression rings on Mahle LT5 pistons before. Can you elaborate on yours? __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

04-27-2015	#8
tpepmeie Join Date: Aug 2005 Location: Fishers, IN Posts: 815	Re: 427 LT5 Build 2 underway I added a couple of links to the original post, just to keep it all together. Some other upgrades for Build II: Custom main bearing studs ARP head studs Cometic MLS head gasket Custom heavy duty secondary cam chains () improved crankcase ventilation upsized fuel delivery system, incl. new rails & adj regulator alpha-n fuel calibration, fully mapped on engine dyno RAM dual disc clutch That's all I can think of right now. This should be fun.

05-04-2015	#9
USAFPILOT Join Date: Aug 2007 Location: Spring TX Posts: 1,348	Re: 427 LT5 Build 2 underway Is this a second engine or a rebuild of the 1st 427? __________________ 1994 #293 ZR-1 Stainless Works Long Tube Headers, B&B catback w/ X-Pipe, 18" Shelby Series One Wheels, SLP CAI.

05-04-2015	#10
bradley Join Date: Aug 2013 Location: ridgecrest ca Posts: 104	Re: 427 LT5 Build 2 underway could you share what your doing to improve the crankcase vent system ??????