JEB99TA

iTrader: (32)

If I go with GM MLS gaskets and 60 cc chamber size and I'm not happy with the overall dyno/track numbers (since I'm having my motor forged later this year, anyway) could I simply switch to the Cometics gaskets for tighter quench and higher compression?

smask04C5

iTrader: (1)

i would not go 60 cc first pass on an afr 205. go to www.smokemup.com and check your dynamic compression. with 62 cc you'll be at 11:1 scr and with a cometic .040-.045 gasket, quench will be ideal.

JEB99TA

iTrader: (32)

That webite says the server has crashed. The Pro Shop ordering/installing my heads just did a C5 and had really great results with the 60cc and GM MLS gaskets and is pretty confident it will be a good chamber size. The thicker gasket is supposed to give you about .1-.2 lesser compression. and doesn't seem like it would chnage the quench. I'm a noob at head spec's, but, the numbers they achieved seem to speak for themselves. Most agree with the 61cc & 62cc w/Cometics, but, a lot of stories out there saying problems with leakage with the Cometics. Once my motor is forged, Strange 12-bolt, 4L60E built, I plan to spray 200-250.

I'm obviously pretty confused about which way to go ... just trying to meet my final overall goal. Any additional information as to why one chamber size is better with certain gasket size would be appreciated. I'm going back to Tin Indian's sticky to read through it again. It's beens aid quench is a big piece of the puzzle. BTW, thanks to everyone for your help ... still seeking advice.

bigdsz

iTrader: (1)

My buddy initally had his heads milled at AFR .024 to bring him to 61 - 62cc. He is now milling another .010 for 59-60 cc. I think the AFR heads start at 66 cc.

smask04C5

iTrader: (1)

correct bigdsz, afr's stock chamber size is 66cc. Had AFR mill .024 to 62cc. It is true that what works well on one setup, may not on another. I guess that is why we keep doing this!

smask04C5

iTrader: (1)

Just installed my crane pushrod guide plates on AFR heads, no problems, spring pocket, rocker boss area is so generous, did not have to machine studs, because they do not extend into the intake port.

JEB99TA

iTrader: (32)

Finalized my order ... decided to go AFR 205's @ 60cc chamber size with GM MLS gaskets and cam will be the 224/228 114+1 ... same cam Tony Mamo recommends ... not sure how tight the quench will be, but, I'm expecting 55-60 RWHP from the combo.

smask04C5

iTrader: (1)

good luck, hope all goes well with install

JEB99TA

iTrader: (32)

The shop owner is notorious for backing his work and had a good success on a C5 LS1, so, I think it will be a good setup/combo. I'll post up the dyno as soona s the install happens. The back-order on the AFR's is about 5 weeks now.

smask04C5

iTrader: (1)

Yes, i ordered mine on June 17th and received last friday July 22nd. thanks to afr and tony, excellent quality workmanship.

JEB99TA

iTrader: (32)

I cannot wait to hear what you dyno. Better yet, your track numbers will be even more interesting, if you run the car after you get them installed. Keep us posted.

FloridaZ

the 205's and that cam size is the combo i'm going with soon. MAN..i can't wait!!
counting the months !

JEB99TA

iTrader: (32)

Since I went with 60cc chamber size, MLS gaskets, and 224/228 .581/.581 114+1 cam, if I'm not satisified, does anyone think I can later change the gasket out for .040 Cometics gasket without getting into PtV issues and quench problems? I think it might actually improve the quench. Sorry about my lack of technical knowledge about heads/cam combo's.

Tony Mamo @ AFR

iTrader: (13)

60 cc's and no valve notches (with an .040 gasket) adds up to a bunch of compression (11.5 ish). Straight pump gas might be a challenge. Who instruted you to mill the heads to 60 cc's?? With that cam you could have ran an .040 gasket, a 62 cc chamber, and you would not have had to notch pistons....also your CR would have been closer to 11.25 CR....more user friendly assuming 92-93 octane availability. If you have pistons with 2 cc reliefs it's obviously the same CR as running 62 cc with flat tops which puts you in pretty decent shape....Good luck

PREDATOR-Z

They were not taking quench in consideration obviously.
I would estimate a good 10rwhp can be had with nice tight quench, and that is true with even stock heads.
Poeple ask me how I get 404rwhp out of a 224/220 + bolt ons on an A4 and I seriously believe it is thanks to a .038 quench, LS6 light effective moving valvetrain mass and the little extra SCR. (241 heads, LS6 valves, 918's, Tit ret. and Cometic .045) The rest is untouched (except for portmatching)

JEB99TA

iTrader: (32)

Guys, there are expert opinions here ... many are tried, true, and tested (on various setups), but, I'm seeing a LOT of numbers stacking up in the favor for others' dyno numbers with the GM MLS gaskets and 59cc chambers ... and on pump gas. I certainly don't want to achieve 11.5:1 compression only to detonate and destroy my engine. The heads/cam should be on the way soon and I'll post up the dyno numbers/gains.

BTW, your advice is greatly appreciated and I have the greatest respect for your guidance. I'll consider everything everyone has contributed here and in other threads I have up. It's nice to know such respected and knowledgeable folks here reply to my posts. I thank you sincerely for that.

I guess it was said best like this: 'depends a lot on the setup of the car and a LOT of variables'

Tony Mamo @ AFR

iTrader: (13)

I think the majority of the opinions would lean the other way (tighter quench with the SAME compression ratio). A tight quench area provides many documented benefits including less emissions....It just makes for a more complete combustion cycle (and arguably slightly higher power output) by more effectively atomizing and utilizing every last drop of fuel. There is no where for any extra fuel and air to "hide" (and not burn effectively) with the piston practically kissing the top of the cylinder head in the quench pad areas. I bet the pistons of a Pro-Stock engine (MAX N/A performance) is slightly kissing the head (or at least "cleaning the carbon off") if you had the chance to examine one after it was torn down....Anybody with some further insight here?

I'm sure this is one of those divided topics (isn't everything??) but my guess is the majority of the engine builders polled would go with the tighter quench approach.

Regards,
Tony M.

JEB99TA

iTrader: (32)

I guess I just don't understand why quench is SOOOO important between 1cc or 2cc of chamber size difference. A cubic centimeter is on the scale of being microscopic when one talks about the power of the explosive combustion that is occuring at such a high rate of quicker-than-lightening speed. It's not like the minute bit of a gas vapor or air is not getting burned ... don't think it could hide in there at such a tremendous velocity of explosiveness.

Looking at scores of setups, some of the H/C setups with 66cc chamber sizes make more power than 59cc chamber sizes and vice versa ... looks (from real numbers) that it works both ways, dependent on the overall setup of the car/motor. One could call my line of thinking Hillbilly-like in nature, and you would certainly be correct. I just don't see that it leaves any more than 1-5 HP on-the-table. That's of utmost importance to alot of folks, but, I sure don't want my pistons within .003-.006" of banging into the you-know what.

I want a safe setup, so, I really don't see what's wrong with my options. All you guys opinions are appreciated a lot. Thanks for weighing in. I just don't see any right accross-the-board answer for the type gsakets and milling/chamber size that is best for all setups in most every case. It's a really opinion-oriented subject. as Mr. Mamo stated, it's one of those divided subjects.

Again, thanks to everyone for your answers ... alot of good insight here.

wallstAL

I had my AFR heads milled .040 by Westcoast Cylinder Heads. They said the chambers came out to 60.6cc. I used the Cometic head gasket .045. I am not sure of the compression, because I can't be sure of the out of the hole value. Using the following calculator I s/b around 11.1:1. http://www.c5frc.com/calculators/Com...Calculator.htm
I have not had the car on a dyno yet, it was tuned by spirted driving with a scanner plugged into the PCM. I made about 8 passes at over 100mph. My programmer asked me if I wanted the engine to last, therefore he did not try to sqeeze every pony out of it, some was left on the table. Since we have 91 Octane here, I add a quart of Torco with each tank. Car runs great, can't wait for cooler weather at the track.

Check the sig for more details!!!

JEB99TA

iTrader: (32)

... appreciate all your responses. I wish I had the knowledge some of you have ... comes from experience, I suppose.