5.3 Jeep build. Head questions
05-12-2010, 08:11 PM
#1
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5.3 Jeep build. Head questions 5.3 build going into a Jeep TJ. Not looking for a max hp effort, but a rather budget build more aimed at power below 4K. I know a 6.0 is going to perform better on the low end, but I already have the 5.3.
I値l be taking the heads (842) in to get a good valve job done, and have them cleaned up.
I知 considering having the intake ports polished, and the exhaust ported and polished. My thinking being that by not porting the intake runners, the velocity will stay higher and be better for low end performance. Is there any truth to this? Or will a mild port and polish outperform all way around???
I値l likely have them milled to true them out, but I知 not looking to bump compression much as I want to run cheapo 87 octane.
What are the compression limits for running 87?
I値l be taking the heads (842) in to get a good valve job done, and have them cleaned up.
I知 considering having the intake ports polished, and the exhaust ported and polished. My thinking being that by not porting the intake runners, the velocity will stay higher and be better for low end performance. Is there any truth to this? Or will a mild port and polish outperform all way around???
I値l likely have them milled to true them out, but I知 not looking to bump compression much as I want to run cheapo 87 octane.
What are the compression limits for running 87?
05-14-2010, 08:57 AM
#4
how much is the head rebuild going to cost?you mite find some low mileage ones that don't need a rebuild,for cheaper. point the intake ports up add solvent with dye to check for leaks,no leaks no need for valve jobs. install new springs and seals. I would not mill them much for 87.look at compcam 54-408-11,or 54-455-11 ,for low end power.what intake are you running?
05-14-2010, 08:57 AM
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From my experience 9.5~:1 is close but given different combinations of cam overlap and timing I've heard of 10.5~:1 cars running on 87. There are a lot of variables including elevation that go in with it too. Lower air density from say living in denver at 5280 ft elevation means that there will be less air/fuel in the chamber creating less cylinder pressure allowing you to run lower octane than say at sea level. I personally have my truck tuned and at sea level require 91 but run 87 here in wyoming at 6100 ft with no problems.
05-14-2010, 08:59 AM
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Car Craft did a 5.3 build with just heads and a cam and twisted 460 crank hp out of it. With just a cam on stock heads they were at like 420 if I remember right. The article is online. I searched gm 5.3 builds in google.
05-15-2010, 12:53 AM
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Call TEA and get some 5.3 ported heads. Shave them down to get the compression up. Get a cam around 212/218 and you should have plenty of torque. Check the truck forum, performancetrucks.net. You'll find all the info you need about truck builds.
