5.3 heads
It can be. With a good valve job and minimal blending, they will outflow 243/799 heads, produce a higher compression ratio, and cost just as much, if not less than the 243/799 heads.
The 5.3L heads have the same valve seats as the 241's and the 243's so in My opinion You can do better by leaving the 1.89's and the 1.55's and just cutting the inner diameter of the seats a little larger . They can be cut to the same as a 1.94 leaving the 1.89's in without as much shrouding by the valve or the side of the combustion chamber . And the exhaust 1's can be cut to the same as a 1.6 . So think about it and take You're pick .
The 5.3L heads have the same valve seats as the 241's and the 243's so in My opinion You can do better by leaving the 1.89's and the 1.55's and just cutting the inner diameter of the seats a little larger . They can be cut to the same as a 1.94 leaving the 1.89's in without as much shrouding by the valve or the side of the combustion chamber . And the exhaust 1's can be cut to the same as a 1.6 . So think about it and take You're pick .
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
TECH Enthusiast
iTrader: (5)
Joined: Jan 2010
Posts: 676
Likes: 2
From: Huntsville, Alabama - SA, TX is home
I just did this to my 5.3 but didnt have $ for a flow test. I am about to see dyno differences soon, but it wont be a measurement of just the larger valves because i also milled .030" and home ported them.
Thread Starter
Staging Lane
Joined: Dec 2012
Posts: 54
Likes: 0
From: jacksonville florida
i have some ported ls1 heads on my car right now but i would also like to see how big of a differnce the bigger valves and more compresiion will do let me know when you get those dyno numbers back
Here is what my 2.02/1.60 5.3's did on the flow bench. Can't tell you how they ran because they've never been installed. Project is getting canceled and they are actually for sale in the classifieds.
TECH Enthusiast
iTrader: (5)
Joined: Jan 2010
Posts: 676
Likes: 2
From: Huntsville, Alabama - SA, TX is home
Got a for sale link?
TECH Enthusiast
iTrader: (5)
Joined: Jan 2010
Posts: 676
Likes: 2
From: Huntsville, Alabama - SA, TX is home
Yeah they were ported/polished as well. I know it won't be a direct comparison to his question but they aren't going to flow that well with the smaller valves either.Sale link:
https://ls1tech.com/forums/parts-cla...s-goodies.html
The 5.3L heads have the same valve seats as the 241's and the 243's so in My opinion You can do better by leaving the 1.89's and the 1.55's and just cutting the inner diameter of the seats a little larger . They can be cut to the same as a 1.94 leaving the 1.89's in without as much shrouding by the valve or the side of the combustion chamber . And the exhaust 1's can be cut to the same as a 1.6 . So think about it and take You're pick .
TECH Enthusiast
iTrader: (5)
Joined: Jan 2010
Posts: 676
Likes: 2
From: Huntsville, Alabama - SA, TX is home
I understand ,I have considered doing 1.94 Intake and 1.59 Exhaust on 5.3s and get them ported. The cheapest route would be just do the the Intake side and swap your LS1 2" over , and run with the 1.55 .The 5.3 already has 1.55 on the exhaust side. Get a performance VJ and some light hand port and call it a day.
TECH Enthusiast
iTrader: (5)
Joined: Jan 2010
Posts: 676
Likes: 2
From: Huntsville, Alabama - SA, TX is home
To answer the orignal question, I dont think you'd see much if any gain from just the 5.3 to LS1 intake valve swap. They flow the same as they are in stock form. But like others have said with a port job and a cam that needs to breath you will see a difference.
I finally got my 2" valve, .030" mill and home port 5.3 with LS6 cam through a 80e dyno'd. 329 rwhp and 334 tq.
Now itching for a larger cam and stall...
I finally got my 2" valve, .030" mill and home port 5.3 with LS6 cam through a 80e dyno'd. 329 rwhp and 334 tq.
Now itching for a larger cam and stall...
