317 or 243 heads with Whipple and 408?
#1
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Jun 2002
Location: Dallas,TX
Posts: 375
Likes: 0
Received 0 Likes
on
0 Posts
317 or 243 heads with Whipple and 408?
I know this question has been presented, but wanted to ask for my specific application to get some ideas. I currently have the LQ4 which I am going to be going through to stroke to 408. I wanted to know what you guys thought about keeping the 317 heads that are currently on there if I am going to be running a whipple with about 10psi. I have read the 317s will work better with boost and give me the lower CR. If that is the case, I would just have them cleaned up and reuse with all stock parts. Would this be advisable, or should I get new rockers, etc.?
#5
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Jun 2002
Location: Dallas,TX
Posts: 375
Likes: 0
Received 0 Likes
on
0 Posts
So you think I will need to upgrade from the stock springs? I have been reading that the heads do play a role in CR also. I was thinking with about 10psi of boost, I wanted to be in the 9.5:1 ratio. That sound right?
#6
TECH Fanatic
iTrader: (1)
While in your case figuring your goals and target ratio, I feel the 317’s cleaned up with a good valve job and better springs will do just fine, compression is not just compression and generally speaking you would be better with the tighter quench a head like the 243’s and “D” shaped pistons offer over a head designed with less quench and a regular bathtub dished piston. Of course there is more to it than that, even different piston designs than “D” shaped, but yes head design plays a big part in the ultimate potential of the engine. With the 317’s and 243’s the basic port design is comparable, yet due to the slightly better combustion chamber design the short turn radius is slightly improved in the 243/799 heads and results in an marginal edge in flow. Again though, I feel in your case a properly prepared set of 317’s will be more than adequate, especially since you already own them.
#7
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Jun 2002
Location: Dallas,TX
Posts: 375
Likes: 0
Received 0 Likes
on
0 Posts
1Bear, thats what I was hoping. I will need to find out how much it would be for the valve job and cleaning. Hopefully not as much as buying a ready to go set of 243s. So I was looking at the TSP rotating assembly for the build. Do you think the K445X3 Wiseco's will work well? It is saying 9.7:1 at -15cc and 70cc of flow, so I should be pretty close to that with the 317s being at 71cc. The other option is the -20cc pistons, which would be 9.3:1.
Last edited by Will; 12-28-2011 at 08:55 PM.
Trending Topics
Thread
Thread Starter
Forum
Replies
Last Post
BigEd_72455
GM Parts Classifieds
0
08-08-2015 04:49 PM