Just bought an lq4
10-19-2009, 06:00 PM
#1
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Just bought an lq4 Well i pulled the trigger on an lq4 today. question 1. how much do i have to mill the stock 317s for 10.5:1 question 2. how much for 11.5:1 question 3. where do you guys get custom cams cut for your lsx motors, if that's too costly what would be a good cam for a stock bottom end lq4, the compression numbers listed above, the heads cleaned up by me (light port), edelbrock performer manifold (or should i just go with the single plane?) 4. after i have the heads milled to get the type of compression i wan't how much will i have to worry about ptv contact, i will definitley clay the pistons before final assembly but would like to hear your advice 5. where do you get the correct length pushrods if the heads are cut? sorry for the long windedness i just know you guys know your sh#*, there's literally nobody better to ask.
10-19-2009, 06:11 PM
#2
only way to get over 11:1 on a lq4 is with milled 5.3 heads.
the stock 317 heads will only go up to around 10:1 with a .030 mill. and thinner gasket, for 10.5: will need milled 243 or 799 heads.
lq4 come with 8cc spherical dish, so it gives room for some ptv clearance.
vic. jr is better than the dual plane manifold. cam and pr is length is up to you, need to verify pr length with new cam and valve train.
the stock 317 heads will only go up to around 10:1 with a .030 mill. and thinner gasket, for 10.5: will need milled 243 or 799 heads.
lq4 come with 8cc spherical dish, so it gives room for some ptv clearance.
vic. jr is better than the dual plane manifold. cam and pr is length is up to you, need to verify pr length with new cam and valve train.
10-19-2009, 06:15 PM
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whats the disadvantage of the 5.3 head over the 317s and what will the c/r be without getting them milled? and also i see alot of guys upgrading to arp rod bolts should i grab a set before i drop this in my car? again sorry for all the questions
10-19-2009, 06:36 PM
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it seems it would probably be wise to go with the rod bolts with the single plane and a decent sized cam so i will definitley pick those up. one last one, 241s even with upgraded springs go cheap. is it worth pickin up a set of those and having them milled especially if i'm gonna clean the ports up anyway (i've done a decent job portin ohc 4.6 heads, flowed them myself to show an improvement over the horrid stock cast ports, was taught a little bit about porting in school and got to utilize a superflow there)?
10-19-2009, 06:49 PM
#6
the 241 need work, just to match the stock 317. and the chamber is really not that much smaller 67 to 71cc for 317. i would not trade flow potential for slightly more scr. if really need more than 10.5:1, will need to find 243 or 799 heads, anything else stock is a downgrade. mill the heads u have now and build around available flow and scr.
member patg on this board spec's excellent grinds based on the available parts.
member patg on this board spec's excellent grinds based on the available parts.
10-19-2009, 06:54 PM
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Awesome thanx for your help man. So do you think if i can mill to a little over 10:1, do a light porting on the heads myself, edelbrock vic jr, holley 750 dp, arp rod bolts, decent sized cam, and tig up a set of longtubes i can hit around 450rwhp (will be less i understand if i end up going with a stalled 400 but haven't made that decision yet)?
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10-19-2009, 08:46 PM
#12
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I think the 243's are an excellent choice for the LQ4. It will put you comfortably over 10:1...someone on here should be able to tell you the exact ratio...somewhere in the ballpark of 10.3, I think. They have 65cc combustion chambers and flow is comparable to the 317. If you aren't going to shift over 6000 and this is a regular street driver, my personal view is the dual plane intake. It will provide considerably more torque in the lower range...there have been a few dyno's done in the mags.
