Milling and flycutting ? with AFR 205's/G5X3
09-13-2005, 12:01 AM
#1
Milling and flycutting ? with AFR 205's/G5X3 I have a stock cube, motor in my 02 Z28. I bought a set of AFR 205's. I was going to install them as is, but I keep hearing that its worth it to mill them, and then flycut the pistons. LG told me that the heads would clear fine if unmilled with my G5X3. If I mill them would I see a much greater HP increase?
What would you guys do?
Also, they are 66cc's. I am wondering how much they should be milled. Ive read about guys going down to 59cc. Is that the right number I should go for, and how much should be taken off to achieve this?
As for flycutting, how much do I need to flycut, if I decide to mill the AFR's?
Any opinions are welcome as to what I should do. Would it ultimately be worth it? Thanks in advance!
What would you guys do?
Also, they are 66cc's. I am wondering how much they should be milled. Ive read about guys going down to 59cc. Is that the right number I should go for, and how much should be taken off to achieve this?
As for flycutting, how much do I need to flycut, if I decide to mill the AFR's?
Any opinions are welcome as to what I should do. Would it ultimately be worth it? Thanks in advance!
09-13-2005, 06:24 AM
#2
every .006 taken off equals one cc.
So .030 off would be a 61cc chamber etc...
The only one who can answer the flycutting tool is you; you'll have to measure. Unless LG has done this and knows how much to flycut. Also don't forget the head gasket for quench. How far out of the hole are your pistons?
So .030 off would be a 61cc chamber etc...
The only one who can answer the flycutting tool is you; you'll have to measure. Unless LG has done this and knows how much to flycut. Also don't forget the head gasket for quench. How far out of the hole are your pistons?
09-13-2005, 08:55 AM
#3
East Coast Superchargers recommended to me to mill down to 58-59CC.
They re-enforced that I was leaving RWHP on the table if I didnt, but I was ok with that. I trust them, and for my cam they said I would not have issues.
I milled to 61cc which seemed just right for me. It's not cut to the edge to get all the HP, but enough for a little differance and not to worry about to much compression. Im using the GM stock gasket. Ive gotten several differant numbers of what thickness is the of the Stock MLS GM gasket is. Ive read the gasket size is .051 and .054, and .060. I used the .051 as my worst case example
Some compressions numbers have me at 10.8:1 and some have me at 11.2:1.
Id like the car to be ok on 91 octaine just in case 93 wasnt availible.
They re-enforced that I was leaving RWHP on the table if I didnt, but I was ok with that. I trust them, and for my cam they said I would not have issues.
I milled to 61cc which seemed just right for me. It's not cut to the edge to get all the HP, but enough for a little differance and not to worry about to much compression. Im using the GM stock gasket. Ive gotten several differant numbers of what thickness is the of the Stock MLS GM gasket is. Ive read the gasket size is .051 and .054, and .060. I used the .051 as my worst case example
Some compressions numbers have me at 10.8:1 and some have me at 11.2:1.
Id like the car to be ok on 91 octaine just in case 93 wasnt availible.
09-13-2005, 12:40 PM
#5
I just read this from Tony Mamo in another thread a while back.......
So I know that Im now going to go ahead and mill them, and flycut. The search button is wonderful! lol I just need to know how much to mill them to get to a 59cc. Is that too much? If so, someone lease chime in.
Also, Im guessing that Im gonna have to see how much I have to flycut when I actually have the heads off of the car, right? Does anyone know how much I should initally cut, and then go from there? I really want to do this right, and not mess it up. Thanks!
Originally Posted by Tony Mamo @ AFR
Guys...
You cant "have your cake and eat it to"....at least most of the time and this situation certainly qualifies as one of them.
Let me elaborate....Installing a cam as large as a GX3 (no matter what LSA) and trying to get away without notching pistons for valve clearance is penney wise and dollar foolish. You MIGHT get away with it with un-milled AFR's out of the box at 66 cc's, but you will still have minimal clearance (which could be a problem if RPM's get away from you in the water box or perhaps a missed shift)....this is not a "desirable" situation. What's even worse is that a stock 66cc head and an X3 cam is NOT a good combination. You could make close to the SAME or perhaps slightly more peak power with a smaller 224 stick because you would have the room to hike the CR up to 11-11.25 to 1, not to mention have much more torque and HP down low from the smaller cam and the higher compression. The average power and torque would simply be alot higher and it would be a much more street friendly set-up. I'm not advocating for everyone to go with a smaller camshaft, what I'm saying is if your taking the plunge with a fairly aggressive cam grind (230 + duration), you need to bump the CR to 11 to 1 minimum, and notch the pistons for adequate valve clearance so your not on the ragged edge (to help avoid tagging a valve in an unforseen situation).
Just because you MIGHT be able to squeeze an X3 cam in your motor with an un-milled AFR doesn't necessarily mean it's the smart thing to do....
Combination, combination, combination....can't drive this home enough. I've seen many milder set-ups out gun a more "radical" one because more thought and time went into the other.
I've been meaning to touch bases on this previously and it is not aimed directly at the "creator" of this thread....in fact I'm glad he posted this because it's a topic I've been meaning to hit on for awhile now. Keep it mild or build it radical, but build it "RIGHT" without trying to cut any corners. You will be much happier in the long run with the increased performance and there is a good chance you might have avoided a potential disaster in the future from valve's clipping pistons or worse.
Tony M.
You cant "have your cake and eat it to"....at least most of the time and this situation certainly qualifies as one of them.
Let me elaborate....Installing a cam as large as a GX3 (no matter what LSA) and trying to get away without notching pistons for valve clearance is penney wise and dollar foolish. You MIGHT get away with it with un-milled AFR's out of the box at 66 cc's, but you will still have minimal clearance (which could be a problem if RPM's get away from you in the water box or perhaps a missed shift)....this is not a "desirable" situation. What's even worse is that a stock 66cc head and an X3 cam is NOT a good combination. You could make close to the SAME or perhaps slightly more peak power with a smaller 224 stick because you would have the room to hike the CR up to 11-11.25 to 1, not to mention have much more torque and HP down low from the smaller cam and the higher compression. The average power and torque would simply be alot higher and it would be a much more street friendly set-up. I'm not advocating for everyone to go with a smaller camshaft, what I'm saying is if your taking the plunge with a fairly aggressive cam grind (230 + duration), you need to bump the CR to 11 to 1 minimum, and notch the pistons for adequate valve clearance so your not on the ragged edge (to help avoid tagging a valve in an unforseen situation).
Just because you MIGHT be able to squeeze an X3 cam in your motor with an un-milled AFR doesn't necessarily mean it's the smart thing to do....
Combination, combination, combination....can't drive this home enough. I've seen many milder set-ups out gun a more "radical" one because more thought and time went into the other.
I've been meaning to touch bases on this previously and it is not aimed directly at the "creator" of this thread....in fact I'm glad he posted this because it's a topic I've been meaning to hit on for awhile now. Keep it mild or build it radical, but build it "RIGHT" without trying to cut any corners. You will be much happier in the long run with the increased performance and there is a good chance you might have avoided a potential disaster in the future from valve's clipping pistons or worse.
Tony M.
Also, Im guessing that Im gonna have to see how much I have to flycut when I actually have the heads off of the car, right? Does anyone know how much I should initally cut, and then go from there? I really want to do this right, and not mess it up. Thanks!
09-13-2005, 02:03 PM
#6
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Which cam do you have the G5X3 on a 112 or 114? Lou mills his heads down to 59cc which works out to a .040 cut. With the cometics .040 that put's you down to around 11.6-8 to 1. The cam performs the best with the heads cut to 59cc-most C5 guys make around 450-460 rwhp. I think you have to flycut the piston .070 on the intake only. Every point in compression is around 4% on power. If you don't mill them that would be like leaving 20 horse on the table when you know you could of had that 20 horse if you spent the few dollars to get the heads milled. 20 horse is like a Fast 90/90! You won't have much trouble with that compression with the overlap of the cam-it's all in the tune.
09-13-2005, 02:15 PM
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I will be running a little under 60 cc with my LS6 heads with the G5X4. The LS6 heads are cut .035 to get there. They were about 65.5 after TEA unshrouded the valves on them. I was told that was the area that the LG stuff like to be compression wise. LG also recommended to me to cut the intake .080 and not to worry about the exhaust with the 60 cc's, .040 cometics, and the X4. Hope that helps
John
John
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09-13-2005, 02:48 PM
#8
Cut them down .042" for 59cc. With a 1cc or .080" flycut on the intake (don't need to on the exhaust), you will be around 11.3:1 CR. With that big of a cam, it works absolutely fine on pump gas. You want the added compression, because a cam that big "bleeds off compression," which is a crappy term for saying that the dynamic compression ratio falls too low, meaning you lose torque at lower RPMs. That's because you don't create enough cylinder pressure to create more torque than you had stock. Also, it can cause vacuum problems at low RPMs and crappy idle/mileage, because you have too much cam. Of course, the G5X3 is not big enough to really affect those things at stock CR when tuned, but you are leaving a good 15HP on the table and some drivability at around town RPMs/speeds. My suggestion is to flycut and mill them down. Run the .040" Cometic for a tight quench to ensure that you have proper burn at the elevated compression.
Also, did you get the G5X3 on the 114? The AFR205s at 59 cc with G5X3-114 make some of the nicest dyno graphs in terms of usable power I have seen.
Also, did you get the G5X3 on the 114? The AFR205s at 59 cc with G5X3-114 make some of the nicest dyno graphs in terms of usable power I have seen.
09-13-2005, 03:10 PM
#9
The G5X3 is on a 114.
Has anyone heard of the Cometic gaskets leaking, b/c of the deck on the block isnt exactly true, after being run for X amount of miles, and having ever so slight warpage? I think I might just go with some GM MLS gaskets.
Has anyone heard of the Cometic gaskets leaking, b/c of the deck on the block isnt exactly true, after being run for X amount of miles, and having ever so slight warpage? I think I might just go with some GM MLS gaskets.
09-13-2005, 03:13 PM
#10
GM uses MLS gaskets as well. The MLS gaskets are designed to seal up well with the imperfections from what I understand because of the multiple layers. I'd run the Cometics. Well worth the money to tighten the quench on a high compression engine.
09-13-2005, 03:19 PM
#12
Originally Posted by Louis
Mill them down to 59, cut 70 thou out of the piston, and run the thinner cometics.
For the record, the X3 with Unmilled AFRs fits just fine. Its got more clearance than a cam only X3.
For the record, the X3 with Unmilled AFRs fits just fine. Its got more clearance than a cam only X3.
09-13-2005, 03:20 PM
#13
Originally Posted by JakeFusion
GM uses MLS gaskets as well. The MLS gaskets are designed to seal up well with the imperfections from what I understand because of the multiple layers. I'd run the Cometics. Well worth the money to tighten the quench on a high compression engine.
09-13-2005, 03:43 PM
#14
If it's your daily driver, I would worry more about detonation due to less than ideal quench than leaks. I haven't heard of the Cometics leaking, and I don't know why they would. Just because it is thinner, doesn't mean there will be bubbles of space created from an uneven block. I very much doubt the block has ridges and valleys that are greater than .040" peak to valley, but if it does and you are concerned about it, just have the surface of the block cleaned up. You know the AFRs will be smooth and straight.
I just don't see milling down for compression to improve DCR if you are going with a less than ideal quench. They go hand in hand.
I just don't see milling down for compression to improve DCR if you are going with a less than ideal quench. They go hand in hand.
09-13-2005, 10:52 PM
#17
No problem. I know about this, because I've researched this exact combo, and it's the combo I would run. That or I would do an XE-R 234/238 .598"/.605" 114+1 LSA cam which is a little more N/A oriented than the G5X3 but otherwise very similar, with the AFR205s with 59cc chambers or AFR225 on 62 milled to 58cc. You're looking at a lot of horsepower with combos like this.
