AFR 205 64cc heads on LS2?
 

I have a set of AFR #1510 CNC ported 64cc cylinder heads I want to install on my 05 Vette MN6. Will the 64cc heads change the stock compression? What are the best head gaskets to use with these heads? I plan to install a stud kit when I put the heads on.

What size cam would work best for street driving and some strip time. Engine has FAST 90, LG Pros, Tuned.

There is a number of online compression ratio calculators you can use to figure out exactly what your compression ratio will be after various modifications. One of my favorite CR calculators: http://www.c5frc.com/calculators/Com...Calculator.htm

As for gaskets...Cometic is very popular and even made-to-order gaskets from them are reasonably priced (~$200). With the mail-to-order option you have granular control over what you want your final compression ratio to be.

More important than your static compression ratio will be your dynamic compression ratio. The cam you choose plays an important part in determining your dynamic compression ratio. With a DCR between 7.5 and 8.5 you will be fine with 91 octane. If you have access to 93 octane then a DCR of 8.8 is doable.

For the AFR heads a "medium" sized cam with the one of the better lobe designs would be a great choice. The LG G5X1 or LG G6X1 are popular and have approximate specs of 228/232.

If you are doing a cam swap you will also want to upgrade the springs. Patriot Gold Extremes are great and very reasonably priced.

If you are doing a cam swap you will want to swap the under drive pulley unless you think you may one day go FI. If you might go FI, then leave the stock pulley in but have it pinned while the steering rack is out.

If you are doing a cam swap you should also swap the timing chain while you are in there. There are reports of people either stretching the stock LS2 timing chain and/or having it break.

Great gains can be had from having the FAST 90 ported.

Several threads state changing the timing chain is a must when doing a cam swap. Most if not all the broken timing chains were due to a cam swap with the old chain. Also agree with MrDrezzUp's cam recomendation. ON A 114 LSA it will have good street manners and give you 450 hp with the 205's and headers. Add a ported Fast and you'll be around 475-480 hp/435-440 tq. You will like the improvement. Good luck.

Those heads will keep your compression the same. Most people use GM's or Cometic's. You can mill the heads and/or run a thinner .040 head gasket for more compression as long as you have adequate PTV clearance. For your application, I would recommend a cam in the 228-236 duration range.

Feel free to give me a call and I'll be happy to help you out.

Seth
205-267-6387

I have purchased from Hinson. Great guys, great service, super fast shipping. :-)

Optimum compression is changes with your cam choice. Its not a one size fits all. More is always better as far as lope and manners and it also helps low end power so dont just go with the rumor mill on what compression should be.

A .040" gasket will bump you to 11.45:1 and should be the minimum with even the most mild aftermarket cams such as a 224 or 228 cam on a 114LSA. A bigger cam would be better with more compression but then runs into fitment issues beyond a 232 on a 114LSA. A 230XFI cam on a 114LSA is good with 11.5:1-11.7:1.

A great set-up near 500rwhp and still decent driveability if the tuner is good would be a 236 XER cam but it wont clear unless you fly-cut and wont allow optimum compression.

Keep in mind that compression helps manners and a 236 on a 114LSA would like to be with 11.7-11.8:1 for 93 pump gas. Use of a dynamic compression calculator will show you actual dynamic compression so you should use one and avoid the rumor mill telling you what will run on pump gas. An 8.7 dcr will run on 93 octane (or 91 at high altitude). So if you have 12.2:1 compression and still have an 8.7 dcr it will run fine on pump gas. There is no magic line that when crossed gets you detonation. If you run 9:1 dynamic compression at sea level on 93 it will just run 2 degrees less timing and wont detonate. The car pulls timing when it cant run it. So many people buuilding strokers at 10.5:1 compression tell me that they run 10.5 becuase they dont want to run race gas. The stock cam on 93 is 10.9 and the manual tells you it can run 87 if you need to so why would you run anything less than stock compression with a bigger cam???

I have a mild cam in there now, 215/230 on 117lsa. I have a ported fast and T/B with U/D pulley, LG Pro headers, double timing chain and a 4.10 rear. I am changing the stock heads to AFR 205's and want a cam for more power but still want it to be good for street driving.

what is wrong with the cam you have now? not enough power? How does it drive? Any driving problems?

The car drives good. I want a little more power for the track. I am running new drag radials this year and want more pull thru the gears. With stock RF it ran in high 11's, want more hp on top end.

I have AFR 205s w/Cometic .040 gaskets (Spin installed) on my '07 LS2 A6 with a LPE GT11 cam, SpinFast 92, ARH headers w/hi flo cats, UD pulley, 160 t-stat and CoW 3:15s an excellent combination. The AFR 205s were like jewelry they had such a nice CNC and finish to them.
I believe we wound up at 11.4 CR, Spin may remember, but this combo pulls hard thru all RPM ranges.
I think you'll be very happy with the AFR 205s. Good luck.

Should be a nice set up when it is done. :cheers:

I prefer the gm gaskets to the cometics. I hear a lot of bad things about cometics and you will get people telling you they are good but Ive never heard a bad thing about the gm's. I dont know a ton about compression but Im running 11.3:1 or 11.4:1 and it runs great on 91 pump gas with my 228/230 cam. Hope you get it figured out.

I have never heard anythng bad about cometics and would like you to list some factual sources for the 'bad info'.

For advanced installs you need and want less quench area which can only come from thinner gaskets than stock. Less quench is less octane sensitive. Bigger quench area is more detontation prone for another flame front.

I have used cometics exclusively for the last 8 years....no issues. I dont know anyone with issues with them (tuners). Fel-pro is my second choice and would go on my car long before a stock gasket because I never use stock thickness.

Keep in mind that milling heads hurts flow so that should only be done once you exhaust the possibility of thinner gaskets first.

For high HP applications, rubber has no place on a gasket. High boost applications and cometics are a proven winner combo.

Use 11.4:1 with a .040" gasket....cometic.

Cams as big as 232XER are great daily driver cams. That will hit 475rwhp with all your bolt-ons.

The AFR 205 heads I am going to install have the number
012 64cc stamped into the head gasket side above the gasket surface. Does this mean that they may be cut?
They are #1510 heads and one of them has a bar code on it with the number 00019091 on it. Does anyone know what these numbers mean?

I didnt think AFR 205 came in 64cc. They are 66cc from the factory. Are they used or were they massaged at AFR?

The 205's come at 66cc, so looks like they've been milled to 64cc. Don't worry about the bar code #.

Seth

I bought them used. The PO got them ported from AFR. The numbers stamped on the head look like factory numbers, match other stamping on heads.

If you are unsure of them and want to get rid of em...................................... ..........pm me .:leaving:

Thanks, but no thanks.