Forced Induction Superchargers | Turbochargers | Intercoolers

aluminum vs iron block

Thread Tools
 
Search this Thread
 
Old Aug 30, 2005 | 08:06 AM
  #1  
FastKat's Avatar
Thread Starter
TECH Addict
iTrader: (10)
 
Joined: May 2005
Posts: 2,487
Likes: 2
From: Pittsburgh, PA
Default aluminum vs iron block

I am putting an LQ4/4L80E in my 1985 Jaguar XJ6. The car's original curb weight is about 4,000lbs. The original engine and trans were very heavy, but so is LQ4/4L80E. I am planning a boosted setup looking for between 600 and 700hp.

What I really want is an aluminum LS1 block because of the lighter weight (I think about 65lbs) because my car is already heavy. I'm worried about being able to hook up as well as having a good distribution for a good feel on the road. Do you think this weight savings is justified or should I go with the beefier iron block because of the higher boosted HP and torque and FI setup is going to produce?
Reply
Old Aug 30, 2005 | 08:12 AM
  #2  
Wet 1's Avatar
TECH Resident
iTrader: (4)
 
Joined: Jul 2004
Posts: 972
Likes: 0
From: USA
Default

At those HP levels go with the alloy block. If you were looking for 1000+ hp I'd say go iron.
Reply
Old Aug 30, 2005 | 08:27 AM
  #3  
1bad2k2ta's Avatar
TECH Apprentice
iTrader: (3)
 
Joined: Jul 2002
Posts: 358
Likes: 0
From: San Antonio, TX
Default

Originally Posted by Wet 1
At those HP levels go with the alloy block. If you were looking for 1000+ hp I'd say go iron.
Ditto
Reply
Old Aug 30, 2005 | 09:55 AM
  #4  
2001WS6Vert's Avatar
10 Second Club
 
Joined: Apr 2002
Posts: 1,755
Likes: 2
From: Cincinnati, Ohio
Default

I was at the TA Nats last weekend and saw Ronnie Duke's Blue vert. He says it makes 1500 (I'll assume fwhp) with a C5R aluminum.
Reply
Old Aug 30, 2005 | 10:26 AM
  #5  
GrahamHill's Avatar
TECH Resident
20 Year Member
Photogenic
iTrader: (6)
 
Joined: Nov 2004
Posts: 821
Likes: 0
From: northeast Miss.
Default

Who all has broken the aluminum block and at what HP level??
Reply
Old Aug 30, 2005 | 12:00 PM
  #6  
sb427f-car's Avatar
SSU'S Vice Mod
 
Joined: Jul 2004
Posts: 2,391
Likes: 0
From: Hazard Co. Maryland
Default

Originally Posted by GrahamHill
Who all has broken the aluminum block and at what HP level??


The retorical question and the answer, "EXACTLY!"
Reply
Old Aug 30, 2005 | 12:26 PM
  #7  
FastKat's Avatar
Thread Starter
TECH Addict
iTrader: (10)
 
Joined: May 2005
Posts: 2,487
Likes: 2
From: Pittsburgh, PA
Default

I'm not so much interested in "breaking" an aluminum block... I'm worried about it flexing and causing serious damaging wear on my rotating assembly.

But that even takes a back seat to the beef of my question... I could start my build right now with my iron block... but do you think it's worth the wait to find an aluminum block?!
Reply
Old Aug 30, 2005 | 01:06 PM
  #8  
Wet 1's Avatar
TECH Resident
iTrader: (4)
 
Joined: Jul 2004
Posts: 972
Likes: 0
From: USA
Default

With that car and HP level I'd certainly be looking for an aluminum block, you're not going to flex or harm your rotating assembly.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Aug 30, 2005 | 01:08 PM
  #9  
sb427f-car's Avatar
SSU'S Vice Mod
 
Joined: Jul 2004
Posts: 2,391
Likes: 0
From: Hazard Co. Maryland
Default

Honestly FastKat, I think the general consensous around here is that if you are concerned about the weight and at those power levels, then wait and find the alum. block.
Reply
Old Aug 30, 2005 | 01:13 PM
  #10  
GrahamHill's Avatar
TECH Resident
20 Year Member
Photogenic
iTrader: (6)
 
Joined: Nov 2004
Posts: 821
Likes: 0
From: northeast Miss.
Default

Originally Posted by FastKat
I'm not so much interested in "breaking" an aluminum block... I'm worried about it flexing and causing serious damaging wear on my rotating assembly.

But that even takes a back seat to the beef of my question... I could start my build right now with my iron block... but do you think it's worth the wait to find an aluminum block?!
3 weeks ago I spent the better part of the day drilling 51 holes in the new hotrod to save a pound... so i may not be the one to ask.

I just question the decision by some f-body owners to trash the light gem of a block because the "think they might" need it.

Irreguardess of what is actually known.

Its nothing new in hotrodding though.
Reply
Old Aug 30, 2005 | 02:46 PM
  #11  
Boostaholic's Avatar
TECH Addict
iTrader: (4)
 
Joined: Sep 2002
Posts: 2,542
Likes: 0
From: Boise, ID
Default

Harlan ran around 1100HP through a aluminum block running 8.2 and hitting high 160's - low 170's in the quarter. I'd say its just preference at your power level.

I personally went with a iron block due to the price.
Reply
Old Aug 30, 2005 | 03:20 PM
  #12  
sb427f-car's Avatar
SSU'S Vice Mod
 
Joined: Jul 2004
Posts: 2,391
Likes: 0
From: Hazard Co. Maryland
Default

If you're going to the trouble Kat, do it right / get what you want!
Reply
Old Aug 30, 2005 | 03:25 PM
  #13  
y2khawk's Avatar
TECH Veteran
iTrader: (5)
 
Joined: Nov 2001
Posts: 4,491
Likes: 1
From: Olmsted Falls, OH
Default

Originally Posted by Boostaholic
Harlan ran around 1100HP through a aluminum block running 8.2 and hitting high 160's - low 170's in the quarter. I'd say its just preference at your power level.
That same block is now in my daily driver along with the pistons. Albeit, not nearly the same boost levels, but 12k miles since April and going strong
Reply
Old Aug 30, 2005 | 04:02 PM
  #14  
Pro Stock John's Avatar
LS1Tech Co-Founder
20 Year Member
Community Influencer
iTrader: (34)
 
Joined: Nov 2001
Posts: 45,338
Likes: 1,770
From: Chicago, IL
Default

Fastkat I would go aluminum to take 75 lbs off that tank you got going there. I'm running a 01 LS6 block.
Reply
Old Aug 30, 2005 | 04:27 PM
  #15  
99SS-T's Avatar
TECH Fanatic
20 Year Member
iTrader: (5)
 
Joined: Apr 2005
Posts: 1,005
Likes: 0
From: Phoenix AZ
Default

Just make sure that you get one of the girdles for the bottom end to tie everythign together. that car is gonna be awesome! GL


John
Reply
Old Aug 30, 2005 | 05:43 PM
  #16  
gnx7's Avatar
TECH Junkie
20 Year Member
Liked
Loved
Community Favorite
iTrader: (28)
 
Joined: Nov 2002
Posts: 3,655
Likes: 277
From: San Francisco, CA
Default

stock ls1/ls6 block, stock crank, good rods/pistons then balance/blueprint everything. ARP bolts....

For your power levels this should be fine. ProStock John and Harlan are making way more power than you intend to and have had no problems. They are both running stock cranks as well I believe with stock main caps with ARP studs!

Spend the money on a quality intercooler and the right sized injectors, nice exhaust, good tuner for your car.

Here is John's combo:
LS6 intake
stock ported OEM TB
stock crank
eagle 6.125 rods
diamond pistons, for 8.2:1 compression, a little sturdier than the off the shelf 9:1 ones
6.0 heads ported with GM MLS gaskets
Big supercharger.....
BigStuff3 (BS3) $$$
Reply
Old Aug 30, 2005 | 10:14 PM
  #17  
mdhmi's Avatar
TECH Fanatic
20 Year Member
iTrader: (1)
 
Joined: Jul 2003
Posts: 1,119
Likes: 1
From: Detroit, MI
Default

I have yet to see a single reason except for price to go with an iron block.

Mark
Reply
Old Aug 30, 2005 | 10:52 PM
  #18  
BLk01SS's Avatar
TECH Enthusiast
20 Year Member
iTrader: (7)
 
Joined: Dec 2003
Posts: 747
Likes: 0
Default

Originally Posted by mdhmi
I have yet to see a single reason except for price to go with an iron block.

Mark


An iron block has less flex than an aluminum. Now that doesn't mean that your motor is gonna blow everytime you boost it. It does mean that its gonna move and has much more chance for diaster than an iron. Iron is cheaper, it weighs more, but if you don't mind the weight. Its the way to go for a budget build. I'm gonna run a C5R block on my setup, but its much more money to go that route.
Reply
Old Aug 30, 2005 | 11:02 PM
  #19  
Pro Stock John's Avatar
LS1Tech Co-Founder
20 Year Member
Community Influencer
iTrader: (34)
 
Joined: Nov 2001
Posts: 45,338
Likes: 1,770
From: Chicago, IL
Default

Harlan made like 1100hp thru a stock alum block and stock crank.

I run those A1 head studs.
Reply
Old Aug 31, 2005 | 06:44 AM
  #20  
EPP's Avatar
EPP
FormerVendor
iTrader: (22)
 
Joined: Mar 2003
Posts: 13,063
Likes: 2
Default

It really is a moot point at the power level that you are wanting to obtain, but the LS2 aluminum block is a little stronger due to the siamiezed cylinder design, where there are no water ports next to the cylinders. You can pick up a new LS2 block for a grand, which also gives you a larger cubic inch engine to start with. Bob
Reply



All times are GMT -5. The time now is 04:39 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE