Dr. Jeckel

iTrader: (12)

Setup would be with current Torquer cam that is on a 112LSA(no advance).

The heads seem very similar in flow characteristics but the main difference is the choice of the 59cc combustion chamber of the patriots as opposed to the 63cc chambers of the PRC's. Both heads are nearly identical in price, because although the PRC heads are initially cheaper, I live in Texas and have to pay sales Tax
I am more inclined to get the PRC heads, but the ability to run my cam and use a much cheaper stock head gasket with the patriots, while making better SCR/DCR numbers is really appealing to me.

-PRC 5.3L stage 2.5 with 2.02/1.575 valves with a .045(thinnest safe gasket, from what I've read) gives me an SCR of 11.04 and DCR of 8.22

-Patriot LS6 "Style" Stage II Heads with 2.02/1.57 valves with a stock .052 gasket gives me an SCR of 11.43 and DCR of 8.50

The PRC heads appear to flow a little better than the patriots, so the question is, will the better DCR of the Patriots win out and produce better numbers and more power under the curve than the PRC heads?

Thanks, James.

Dr. Jeckel

iTrader: (12)

Also wanted to mention the setup will include a F.A.S.T. 90mm intake and PTM 90mm TB.

Dr. Jeckel

iTrader: (12)

I just had an idea to maybe put in a smaller cam with the heads, like the 228R with a 112+2LSA. When I chose my cam, I really didn't think I was going to be able to do heads and so my selection was that of a "cam only" car. I have been reading alot and now that I am going to do heads, I have started to re-think my initial cam selection.

PRC heads with a .040 head gasket (assuming this would work since the smaller cam) would give me a SCR of 11.18 and a DCR of 8.62

Patriot heads with stock gaskets would give me a SCR of 11.43 and DCR of 8.81

The compression at these levels worries me a bit, since I am unsure if this is still "pump gas friendly". Could someone reassure me please.

I know the smaller cam would probably drop me down by about 10rwhp, but the increased drivability and low-end torque gains would be worth it to me. It seems like one of these setups would better suit my DD car.

Any comments would be greatly appreciated.

Thanks, James.

brad8266

iTrader: (23)

Id go with the patriots with a thin head gasket due to tight quench.

Dr. Jeckel

iTrader: (12)

Could you elaborate a little on your response? Do you think I should go to the 228R?

I calculated the patriots with the 228r and a .045 gasket and came out with a SCR of 11.64 and a DCR of 8.97.....I no genius, but I think this would be a bit much to run on the street with pump gas

anyone wanna tell me otherwise?

brad8266

iTrader: (23)

No i would run the torquer with the patriots and a thin gasket. Flycut if need be.

Dr. Jeckel

iTrader: (12)

Wanna comment on the compression ratios and ability to be used with pump gas?
Also, is it true that the patriots still have stock PTVC because the chambers are 59cc with no milling done, so they would work with a .045 gasket with the Torquer?

Patriots, T2 and .045 gasket yield an 11.64SCR and 8.65DCR

Irocss85

iTrader: (1)

that sounds like a good setup. how does patriot get 59cc chambers? welding them up? Ive heard about that but am unaware what heads they do this to.

brad8266

iTrader: (23)

I run 11.9 8.7 on pump gas no problem, my quench area is tight too.

Yes the patriot heads use welded chambers to drop chamber size rather than milling. This allows a major advantage in PTVC in small chamber/high compression setups. I would imagine they would work with a .045 gasket, dont hold me to that though, i always say measure first.

brad8266

iTrader: (23)

yeah they weld the chambers. They do it to the stage 2-3 heads.

Dr. Jeckel

iTrader: (12)

I'm just trying to really undertstand the affect that DCR has on performance and what is the relationship between raising the DCR and increase hp/tq. I know that increased compression gives better torque and a little better hp, but I would like it if someone could give a direct relationship between the two.
For instance; Lets compare the patriots with a .045 gasket using the Torquer and 228R camshafts. They both have the same SCR, but the 228R yields a 8.97DCR and the Torquer a 8.64DCR. What kinda number differences would these different setups produce, not just peak, but down low too? Like I said before, I would love a car that really had the torque down low and throughout the powerband, even if I lost 10rwhp up top.
It seems to me that the 228R setup would produce amazing torque down low and throughout the powerband...that is if the DCR is not to high for pump gas.
Sorry for the long read, but I always hear everybody talking about high DCR being the best(I know its the combo too), but I am trying to put some kind of hp and tq numbers to changes in DCR.

Thanks again, James.

Irocss85

iTrader: (1)

well, scr is static compression ratio. thats just a blanket statement and very general, because it has no way of determining airflow and sealing and stuff. like, how effective would 20:1 be if the intake valve was ALWAYS open? you wouldnt build much actual compression. so DCR takes the cams timing into effect. giving you a better representation of actual cyl. press.s your eng. will see. sooo, the longer the vavle is held open (duration #s: 232 or 228degrees of open rotation) the lower DCR will be.
not so sure the welded chambers are best for you if your gonna go with the 228. you want the head gasket to be around .040 because the piston is goin to be near .005 to .008 out of the hole, you take that away from the gasket thickness, and that gives you the quench area. the best quench area is around .035". so you CAN use a stock MLS gasket to lower the dcr back to where you want it, but the better way would be a slightly bigger chamber and the thin gasket to reach the final DCR# you want.
8.97 might work, but it would need a perfect tune to avoid spark knock on 91 octane. Ive heard 8.7 is about the highest you want to be and be safe. however maybe someone with more knowledge then me will chime in here if theyve run DCR that high and was ok or not.

Dr. Jeckel

iTrader: (12)

I'm sorry, maybe I should have explained myself better. I know what SCR and DCR is, but what I'm really looking for is what numerical effect they actually have on horsepower and torque. For example; For every 1/10th of a point raised for your DCR will increase your horspower and torque by "X" amount. I realize it is not this easy, but this is the kinda information I am trying to get.
You did have an excellent explanation and defintely cleared up "quench" for me. I would like to know what kinda setup (with 228R cam) would produce the best results and if the tighter quench of going with a .040 gasket on the PRC heads (while having a lower 8.64DCR), would actually produce better results than say the Patriots with a .045 gasket (8.97DCR).
I am trying to get a grasp on the actual mathematics, that explain the mechanics involved, and which is a better way to produce all around better power.
Everybody has they're own opinion about what is better, but no one ever seems to be able to have the numbers and mathematics to back it up.

Thank you very much for your help Irocss85 and if someone has anything else they would like to add, please do.

I would like to definitely verify the highest safe DCR you can run on premium gas.

Dr. Jeckel

iTrader: (12)

Read the entire Patrick G cam thread and I think I now understand less ...j/k
It was very helpful and really showed me that I am not really going to get the answer I want, because there is SO MUCH that goes into it.
I really think I am going to go back to the 228R, mainly for drivability but also the ability to run a .040 gasket with the PRC heads.
It appears that the compression ratios would be to much with the Patriots, while trying to get a proper quench.

Looks like reading does help after all

If has anything else to add, please do.

Patrick G

iTrader: (14)

Compression is your friend. Since the flow between the heads is close, go with the head that has the compression advantage. I agree with Brad, go with the .040" gasket. Go with the smaller cam too, you will make more power where you use it 99% of the time.

Dr. Jeckel

iTrader: (12)

Thank you Patrick, but how much compression can I run with 91 octane (most we have around here)?
I calculated the 228R 112+2 with Patriot Heads that have a 59cc chamber and using a .040 gasket and I got 11.80SCR and 9.09DCR. I would love to be able to run this setup, but somehow I doubt I will be able to get away with pump gas with this setup and this is my DD so race gas is outta the question.


BTW, all these calculations were done with pianoprodigy's spreadsheet.

Irocss85

iTrader: (1)

seems to me that amirillo gets pretty hot for long periods to right? heat also compounds the DCR-vs-octane rating equation. (I think? right?)

but the reason noone has a mathmatical answer that you can produce X HP/TQ with X DCR is cause thats impossible. I saw a post this morning where a guy swapped head gaskets "ONLY" and went from stock .054" mls to .040" cometics and gained like 12HP and 25 torque at the wheels nothing else changed. https://ls1tech.com/forums/dynamometer-results-comparisons/694946-visit-3-lg-motorsports-pre-install-new-numbers.html

brad8266

iTrader: (23)

Get an adjustable timing set and install retard the cam or just have a different cam ground and line it dot to dot. Thats one way to drop the DCR. You could also run a bigger cam that will bring DCR down too.

There are so many ways to spec out a combo. It gets confusing.

99blancoSS

iTrader: (115)

The patriot 243 head is a good deal as are the PRC's. You can shave any head to bring compression up. I went the prc route but I'd like to see the same cam with the ls6 heads. I know someone who's been doing some good stout combo's with prc 2.5 ls6 heads as well so the Patriots at the price intrigue me. I wish I had a few cars and an unlimited budget. I'd test them all with the same cam and combustion chamber size (compression) and see what works best.

Dr. Jeckel

iTrader: (12)

Thats what I'm saying

Amarillo does get hot for awhile in the summer, but mid 90's is the norm and that was an interesting thread.

I know I could change alot of things to lower my DCR, but it seems that with the PRC heads(63cc) and .040 gasket I would be at about 8.64 DCR. It looks like the maximum recommended DCR ranges from 8.5 to 8.7, depending on octane.

I think this setup would produce about the highest DCR I could run safely and with the .040 gasket I would have the best quench also. So other than specing out a custom cam, this looks like a pretty good choice, atleast IMO