LS1TECH - Camaro and Firebird Forum Discussion

Generation IV Internal Engine 2005-2014 LS2 | LS3 | LS7 | L92 | LS9

Promaxx small bore LS3 heads...

Thread Tools
 
Search this Thread
 
Old 10-08-2021, 02:13 PM
  #21  
8 Second Club
iTrader: (13)
 
SLOW SEDAN's Avatar
 
Join Date: Jan 2010
Location: No VA
Posts: 4,025
Received 945 Likes on 701 Posts

Default
Originally Posted by Che70velle
You boosting this one?
A 3.80 bore would be anemic NA
SLOW SEDAN is offline  
Reply Like
The following users liked this post:
jayyyw (10-08-2021)
Old 10-08-2021, 08:34 PM
  #22  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by Che70velle
You boosting this one?
Yup, again. lol
jayyyw is offline  
Reply Like
Old 10-10-2021, 03:47 PM
  #23  
TECH Fanatic
iTrader: (5)
 
64post's Avatar
 
Join Date: Nov 2011
Location: Sonoma Co. Ca.
Posts: 1,689
Received 226 Likes on 179 Posts

Default
Originally Posted by jayyyw
I'll be running them on 3.800" bore. Need a little smaller exhaust valve to clear.
Why, again?
64post is offline  
Reply Like
The following users liked this post:
G Atsma (10-10-2021)
Old 10-10-2021, 03:58 PM
  #24  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by 64post
Why, again?
I sold my last setup/car. Building another.
jayyyw is offline  
Reply Like
Old 10-27-2021, 11:44 PM
  #25  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by Mavn
Thinking of grabbing a bare pair of the small bore ls3s for a n/a ls1 build. And having valves put into them, blended and valve job done. Maybe do a cleanup of the runners .

They look like an as cast version of the mast small bore 240cc ls3 heads.
Definitely look the same. Flow numbers are fairly close as well. According to each website. They are hefty.
jayyyw is offline  
Reply Like
Old 10-28-2021, 09:28 AM
  #26  
8 Second Club
iTrader: (13)
 
SLOW SEDAN's Avatar
 
Join Date: Jan 2010
Location: No VA
Posts: 4,025
Received 945 Likes on 701 Posts

Default
Originally Posted by jayyyw
Definitely look the same. Flow numbers are fairly close as well. According to each website. They are hefty.
No doubt! Something like 10lbs heavier and moves the exhaust port up a bit. Some of the shaft rocker setups don't fit them either.
SLOW SEDAN is offline  
Reply Like
Old 10-30-2021, 07:58 AM
  #27  
12 Second Club
iTrader: (4)
 
fastlt1's Avatar
 
Join Date: Sep 2005
Posts: 1,502
Received 18 Likes on 9 Posts

Default
Any of these small bore small combustion chamber heads 6 bolt
fastlt1 is offline  
Reply Like
Old 11-05-2021, 06:30 AM
  #28  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by SLOW SEDAN
No doubt! Something like 10lbs heavier and moves the exhaust port up a bit. Some of the shaft rocker setups don't fit them either.
They also have deep spring pockets. Hopefully the BTR shaft rocker system works with them, lol.
jayyyw is offline  
Reply Like
Old 11-05-2021, 06:32 AM
  #29  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by fastlt1
Any of these small bore small combustion chamber heads 6 bolt
Promaxx and the Mast 240cc heads are 6 bolt heads
jayyyw is offline  
Reply Like
Old 11-17-2021, 08:54 PM
  #30  
TECH Fanatic
 
jayyyw's Avatar
 
Join Date: Dec 2017
Posts: 1,284
Received 760 Likes on 387 Posts
Default
Originally Posted by SLOW SEDAN
No doubt! Something like 10lbs heavier and moves the exhaust port up a bit. Some of the shaft rocker setups don't fit them either.
Confirmed that the BTR shaft rocker system DOES NOT work with the Promaxx heads. Rocker spacing is different. Roughly a 1/4" closer together.
jayyyw is offline  
Reply Like
The following users liked this post:
Corona (11-18-2021)
Old 11-21-2021, 10:38 AM
  #31  
TECH Senior Member
iTrader: (4)
 
99 Black Bird T/A's Avatar
 
Join Date: Nov 2001
Posts: 8,590
Received 1,442 Likes on 1,000 Posts

Default
Has anyone purchased a set of Promaxx LS3 small bores and have experience to share?


Thoughts on intake & cam for a stock bottom LS1?

Thoughts on intake & cam for a stroker 383 LS1?
99 Black Bird T/A is offline  
Reply Like
The following users liked this post:
wannafbody (11-21-2021)
Old 11-22-2021, 01:53 AM
  #32  
Banned
 
Corona's Avatar
 
Join Date: Oct 2020
Posts: 1,984
Received 679 Likes on 554 Posts
Default
Originally Posted by 99 Black Bird T/A
Has anyone purchased a set of Promaxx LS3 small bores and have experience to share?


Thoughts on intake & cam for a stock bottom LS1?

Thoughts on intake & cam for a stroker 383 LS1?
Quick answer
it'll avg out just like any other aftermarket heads....
383 stroker with Tfs 220 heads or stock bottom end with again Tfs 220 heads. The Promax being Ls3 could use the factory intake. Output would be similar.
13.5 valve angle vs 11 degree and a larger Rectangular port.

Cathedral head test with Mast Ls3 heads ...imagine the same test with a 3.9xx bore

Last edited by Corona; 11-22-2021 at 02:44 AM.
Corona is offline  
Reply Like
Old 04-13-2023, 10:27 AM
  #33  
Registered User
 
jaredtaylor22's Avatar
 
Join Date: Apr 2023
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Default
Hey did you ever have the promaxx small bore heads 2.08/1.60 valves on a 3.800 bore without notching the cylinder?
jaredtaylor22 is offline  
Reply Like
Old 09-16-2023, 05:41 PM
  #34  
On The Tree
 
Shtstr's Avatar
 
Join Date: Dec 2022
Posts: 152
Received 17 Likes on 14 Posts
Default
Been looking at using these lately on my ls1 n/A build. Glad I found this thread and read the comments. As I can't get any answers from promaxx. Have sent them messages through their website 3 times over the last 4 weeks.
wanted to know if the exhaust ports where in the standard location. But according to a post above they aren't as they are higher up on the heads.
guess I won't be using them now. Bugger back to the drawing board.
Shtstr is offline  
Reply Like
Old 09-16-2023, 10:42 PM
  #35  
TECH Veteran
Thread Starter
iTrader: (2)
 
wannafbody's Avatar
 
Join Date: Apr 2006
Location: Pittsburgh
Posts: 4,700
Received 830 Likes on 633 Posts

Default
I'd try calling Summit Racing. I think they sell ProMax stuff.
wannafbody is offline  
Reply Like
Old 10-14-2023, 06:50 AM
  #36  
On The Tree
 
Shtstr's Avatar
 
Join Date: Dec 2022
Posts: 152
Received 17 Likes on 14 Posts
Default
Originally Posted by wannafbody
I'd try calling Summit Racing. I think they sell ProMax stuff.
Summit don't have any listing for promaxx heads on their website.
Shtstr is offline  
Reply Like
Old 10-14-2023, 07:14 AM
  #37  
On The Tree
 
Shtstr's Avatar
 
Join Date: Dec 2022
Posts: 152
Received 17 Likes on 14 Posts
Default
Originally Posted by SLOW SEDAN
No doubt! Something like 10lbs heavier and moves the exhaust port up a bit. Some of the shaft rocker setups don't fit them either.
How much do the exhaust ports move??
Shtstr is offline  
Reply Like
Back to Subforum
Generation IV Internal Engine
View Next Unread
R.E.D. sleeved Gen IV 5.3 vs LSR block




Advanced Search
Quick Reply: Promaxx small bore LS3 heads...


Reply Closed Thread Share

All times are GMT -5. The time now is 04:26 PM.