Head terms question
Thread Starter
11 Second Club
Joined: Sep 2004
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From: Houston, TX
Head terms question Hi...new to this board, been reading a lot about heads/cam since i'm planning on doing this in about 2 months. anyway, i have a couple quick questions I couldn't find answers for:
1 - what exactly does stage 1, 2, and 3 mean as far as heads are concerned?
2 - what is the difference between CNC finish and hand-prepped race finish? i'm assuming the hand finish is just smoother, yielding higher flow rates? If i'm looking at $2k for CNC and $2.5k for hand finish, what is that extra $500 going to accomplish?
3 - My understanding is 5.3L heads will yield a higher compression ratio - what are the real downsides to this?
My current mods are below, i'm thinking hard about the TR230/224 111lsa with some st2 5.3L heads. I've read quite a few good things about the TR230 (and a few bad of course). Car is my daily driver for now, just trying to get a handle on how this may affect it.
1 - what exactly does stage 1, 2, and 3 mean as far as heads are concerned?
2 - what is the difference between CNC finish and hand-prepped race finish? i'm assuming the hand finish is just smoother, yielding higher flow rates? If i'm looking at $2k for CNC and $2.5k for hand finish, what is that extra $500 going to accomplish?
3 - My understanding is 5.3L heads will yield a higher compression ratio - what are the real downsides to this?
My current mods are below, i'm thinking hard about the TR230/224 111lsa with some st2 5.3L heads. I've read quite a few good things about the TR230 (and a few bad of course). Car is my daily driver for now, just trying to get a handle on how this may affect it.
Last edited by RawWS6; Sep 6, 2004 at 04:03 AM.
1) head stages are whatever the vendor wants them to be, theres no industry standardization
2)hand finishing removes the rough lines left by cnc'ing and in the hands of a proficient hand ported can yeild quite a bit more flow. for an all out max setup spend the extra for hand finishing
3) at ~ 10.8-11.0 CR (assuming unmilled 5.3's and gasket variances) there is no down side. with that compression level and tuning there is no reason pump gas cant be used.
i had a 230 back in the day, its an old but still good cam but in this day and age i'd look at somethhing else. depends on your overall goals. i wouldnt get the 230 with your low stalled a4.
2)hand finishing removes the rough lines left by cnc'ing and in the hands of a proficient hand ported can yeild quite a bit more flow. for an all out max setup spend the extra for hand finishing
3) at ~ 10.8-11.0 CR (assuming unmilled 5.3's and gasket variances) there is no down side. with that compression level and tuning there is no reason pump gas cant be used.
i had a 230 back in the day, its an old but still good cam but in this day and age i'd look at somethhing else. depends on your overall goals. i wouldnt get the 230 with your low stalled a4.
Thread Starter
11 Second Club
Joined: Sep 2004
Posts: 121
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From: Houston, TX
damn jrp, that was fast - didn't figure many people were up at this hour (I'm in england right now)! I read your cam guide the other day, good information, need a head guide now!
I guess as far as the hand finishing, if i don't plan on having this a full-out race car, i'm probably wasting my money?
the stall is another thing i was curious about - i don't have any plans to change it now, but may do so if i end up buying another car for my daily driver. when does this cam start to really make power (in your experience)? Would i be actually losing any power down low, compared to the stock cam?
I guess as far as the hand finishing, if i don't plan on having this a full-out race car, i'm probably wasting my money?
the stall is another thing i was curious about - i don't have any plans to change it now, but may do so if i end up buying another car for my daily driver. when does this cam start to really make power (in your experience)? Would i be actually losing any power down low, compared to the stock cam?
the 230 is a top end cam for sure, its one reason you really need 4.10's in a m6 and a big stall for an a4. also with the 111lsa and a4 you'd want a good tune as well. the cam lopes hard if thats what your looking for.
you have to decide if a few cfm and hp are worth x amount of dollars for hand porting. if you want to and have the time i'd see what the new AFR 225's are like, should be a great head out of the box and
when a good head ported gets a hold of them.
and welcome by the way
.
you have to decide if a few cfm and hp are worth x amount of dollars for hand porting. if you want to and have the time i'd see what the new AFR 225's are like, should be a great head out of the box and
when a good head ported gets a hold of them.and welcome by the way
. Thread Starter
11 Second Club
Joined: Sep 2004
Posts: 121
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From: Houston, TX
OK, thanks for the good information. I'll make some queries about the flow rates and expected gains of the hand polishing before I decide. These heads are actually Thunder Racing's own heads - next step is to check if anyone else is using them...I don't know how long they have been around. Thunder sells the AFR heads as well, i'll search around for info on them. I've got about 2 months until I get back to the states and start worrying about making a decision.
I'm sure I will get the car dyno tuned, and i'm planning on having thunder do the install/tune - nice hard lope is what i want, as long as it runs! If anyone can make it run right, I would hope they can.
thanks for the info and the welcome, i'm glad i finally got around to signing up over here!
I'm sure I will get the car dyno tuned, and i'm planning on having thunder do the install/tune - nice hard lope is what i want, as long as it runs! If anyone can make it run right, I would hope they can.
thanks for the info and the welcome, i'm glad i finally got around to signing up over here!
