Which afr heads
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
Which afr heads
I'm planning on buying a set of afr heads and I am contemplating on whether I should get the ones with 65cc or 75cc chambers. I have flat top Pistons in my engine and thinking I have too much compression since I get a lot pre detonation when the temp is running around 200+ degrees.
Racer
Joined: Mar 1999
Posts: 258
Likes: 13
From: New Mexico
I'm planning on buying a set of afr heads and I am contemplating on whether I should get the ones with 65cc or 75cc chambers. I have flat top Pistons in my engine and thinking I have too much compression since I get a lot pre detonation when the temp is running around 200+ degrees.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
My motor isn't completely stock. I rebuilt it when I bought the car. Original motor had dished Pistons. I put in flat tops. I also put in a zz4 cam. And I had a custom chip put in for my engine specs. I also have the Bosch 3 injectors. I have my ign timing set at 6. I've tried 4 but same thing still happens. I've e replaced the egr valve also thinking that was it. But it wasn't.
Last edited by kitttransam; Jan 17, 2016 at 11:16 AM.
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Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
How did you determine it was pinging? Did you check the ECM for knock? What about fuel pressure? Oil pump should not cause knocking issues. When did you get the Bosch 3 injectors? Have they been checked? Have you checked the fuel pressure regulator for holding pressure? What about WOT pressure? Does it drop off? Maybe your custom chip is off?
Also timing. How do you know that the timing is right? Could your harmonic balancer be walking on you? I would check timing again and if it is 6 still, put a white stripe on the balancer and run for a bit. If it moves, toss the balancer. That could affect your timing so you might THINK you are at 6 when you are at 20.
Also who wrote the custom chip?
Also timing. How do you know that the timing is right? Could your harmonic balancer be walking on you? I would check timing again and if it is 6 still, put a white stripe on the balancer and run for a bit. If it moves, toss the balancer. That could affect your timing so you might THINK you are at 6 when you are at 20.
Also who wrote the custom chip?
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
I have checked the fuel pressure. Tried adjusting it and still same results. Fuel pressure holds at wot. I replaced my balancer also thinking the same thing maybe slipped but that didn't solve anything either. I've hooked up and auto X-ray and drove it. And it is reading a lot of knock counts. I've done most of the checking and poking around the last couple years when time was available.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
I have checked the fuel pressure. Tried adjusting it and still same results. Fuel pressure holds at wot. I replaced my balancer also thinking the same thing maybe slipped but that didn't solve anything either. I've hooked up and auto X-ray and drove it. And it is reading a lot of knock counts. I've done most of the checking and poking around the last couple years when time was available.
http://hitechmotorsport.com/index.ph...art&Itemid=274
Team Owner
Joined: Jul 2004
Posts: 28,472
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From: Hartford WI
Have you talked to Scott and see if he can datalog and give you some idea of what is going on?
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
I'll see about talking to Scott about doing that. Sounds like a good idea.
Heck the car does run great. But let's just say I was going to take a 60 mile trip somewhere on a hot day. By 50 miles on the freeway I start getting problems. Then I get into town cars running hot like every c4 does. Pinging and the whole works. I shouldn't have any cooling problems have a Dewitt's radiator.
Heck the car does run great. But let's just say I was going to take a 60 mile trip somewhere on a hot day. By 50 miles on the freeway I start getting problems. Then I get into town cars running hot like every c4 does. Pinging and the whole works. I shouldn't have any cooling problems have a Dewitt's radiator.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
You should get the 64cc heads, the 64 cc head will drop your compression by .75 of a point. Depending on what you have for parts the compression you have with the 58 cc heads is 10.9 and the 64cc heads will be 10.15. The 75 cc head will yield 9.0 to 1. You need to work on your temperature, you should not run a high compression, high performance sbc above 200 degrees. Program the chip to turn the fans on at 200 and off at 196. Also check you squish clearance it needs to be around .040 to be effective. Once these issues are addressed you will not have problems.
Thread Starter
Racer
Joined: May 2009
Posts: 364
Likes: 3
From: merced ca
You should get the 64cc heads, the 64 cc head will drop your compression by .75 of a point. Depending on what you have for parts the compression you have with the 58 cc heads is 10.9 and the 64cc heads will be 10.15. The 75 cc head will yield 9.0 to 1. You need to work on your temperature, you should not run a high compression, high performance sbc above 200 degrees. Program the chip to turn the fans on at 200 and off at 196. Also check you squish clearance it needs to be around .040 to be effective. Once these issues are addressed you will not have problems.
Last edited by kitttransam; Jan 17, 2016 at 07:27 PM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
I'll see about talking to Scott about doing that. Sounds like a good idea.
Heck the car does run great. But let's just say I was going to take a 60 mile trip somewhere on a hot day. By 50 miles on the freeway I start getting problems. Then I get into town cars running hot like every c4 does. Pinging and the whole works. I shouldn't have any cooling problems have a Dewitt's radiator.
Heck the car does run great. But let's just say I was going to take a 60 mile trip somewhere on a hot day. By 50 miles on the freeway I start getting problems. Then I get into town cars running hot like every c4 does. Pinging and the whole works. I shouldn't have any cooling problems have a Dewitt's radiator.
I'd be curious as to why it does what it does since the car should reach open loop way before 50 miles. In summer, within 10 minutes, it should be at a stable operating temp which mine does. What temp does the ECM see at that point?
A WAG is that maybe you have a sensor that gives bad feedback because the engine area is hot enough and the metals expanded enough to cause a gap and change resistance? Just a WAG.
Last edited by aklim; Jan 17, 2016 at 07:49 PM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
I think this answer is sounding legit. Even my dad that is a retired auto tech. Told me the same thing. Higher compression could cause problems. That's why I was thinking of getting the heads in the first place.my chip is programmed to come on sooner than stock. I want to say 210.