Here's some info I posted in another thread...also throwing in the Patriot Performance and LPE heads:

Stock LS1 Heads 66cc Combustion Chamber
Valve Lift Intake Exhaust
.200 122 97
.300 178 133
.400 215 156
.500 219 170
.550 223 176

AFR 205cc 66cc combustion chamber
Valve Lift Intake Exhaust
.200 140 112
.300 200 170
.400 251 203
.500 281 221
.550 292 226

Dart Pro 1 205cc 62cc combustion chamber
Valve Lift Intake Exhaust
.200 156 109
.300 215 154
.400 258 187
.500 290 205
.550 298 210

ETP 215cc 11 degree casts 62cc combustion chamber
Valve Lift Intake Exhaust
.200 152 106
.300 219 152
.400 266 190
.500 301 204
.550 312 208

Patriot Performance Stage II 59cc combustion
Valve Lift Intake Exhaust
.200 140 124
.300 202 160
.400 244 196
.500 280 220
.550 291 226

LS6 LPE SWGT 240 Runner 60.9 combustion chamber
Valve Lift Intake Exhaust
.200 150 117
.300 225 168
.400 273 202
.500 291 217
.550 304 221
.600 311 222

Trick Flow
215cc LS-1
Intake Exhaust
0.1 66 54
0.2 138 118
0.3 218 187
0.4 272 231
0.5 308 252
0.55 318 258
0.6 324 262

Texas Speed PRC LS6 Stage 2.5 heads 64.5cc, 2.04 1.575 valves, 237cc ports...
Valve Lift Intake Exhaust
200 151 124
300 209 160
400 260 194
500 293 217
600 315 227

The Dart head seems to be closer to the ETP heads then the AFR heads with the numbers that the manufacturers present. In addition the darts come with 62cc combustion chambers that will bump the compression to 10.8-11.1 depending on the gasket used.

I'm not sure of the significance of the better exhaust numbers of the AFR heads but it seems to be commonly excepted that the ETP heads make big power and if I knew nothing else about the head I would think the dart heads would perform better than the AFR heads as they are, like I said, more similar to the ETP than they are to the AFR. Any thoughts?

Another thing is that people don't seem to respect the Patriot Performance heads...or at least they don't oftern consider them in thier builds. However, the Patriot Performance heads
are so similar (looking at the numbers) to the AFR heads plus a 59cc combustion chamber to boot...I would think they would perform at least as well as the AFRs.

What the heck gives...which are the "best" out of box head?? If I wanted to invest a chuck of money in heads, which would you go with and why? Just looking at the above numbers it looks like the LPE heads or Trick Flow are the winner for a big HP build.

 

One of my winter projects

LS6 LPE SWGT
240 Runner
60.9 combustion chamber

Valve Lift Intake Exhaust
.200 150 117
.300 225 168
.400 273 202
.500 291 217
.550 304 221
.600 311 222


Still working on what cam to use.

possibles:
comp 232/234 595/598 112 XE-R XER281HR

or

LG GX3 234/242 600/610 112

 

Dont forget the TFS 215 Heads.

215cc LS-1
Intake Exhaust
.100 066 054
.200 138 118
.300 218 187
.400 272 231
.500 308 252
.550 318 258
.600 324 262


During the development stage, Trick Flow engineers determined that
the valve angles needed to change from 15* to 13.5*. This change
decreased valve shrouding,increased mid-lift airflow,and increased
rocker arm-to-valve cover clearance.Testing also proved that relo-
cating the spark plug position in the combustion chamber further
enhanced combustion along with mid lift airflow and improved the
integrity of the casting in the chamber area. Trick Flow also added
additional material to the decks (.600") and to the rocker arm
mounting pads to improve high rpm valve train stability.

These new fully CNC-ported heads feature 215cc intake runners,
80cc exhaust runners,64cc combustion chambers,2.040" intake valves,
1.575"exhaust valves,bronze valve guides,and ductile iron intake
and exhaust seat inserts.

Assembled heads come equipped with stainless steel intake and
exhaust valves, 1.300"dual extreme pressure (150# seat 450# open)
valve springs for lifts up to .650",viton seals,machined spring
locators, 7 degree titanium retainers and machined steel locks.

One last important feature of this 13.5* head design is the valve
drop.This head features a .155" valve drop on the intake, a stock
5.7 head with 2.00" valves has around .150". What this means is you
can run this head on stock pistons with large camshafts and still
have more piston to valve clearance than a stock head and also
more compression.


Note:Flow numbers are based off of an average of 5 heads tested.
All flow numbers are tested on a 3.900" fixture @28"h20, using
clay intake radius,and a 4"x 1-7/8"pipe on exhaust.

 

Added LPE and Trick Flow to the original post...thanks guys

 

Adding the stock numbers into the mix for giggles!

 

I prefer a smaller runner head, max compression and max DCR. Especially with a cam that is large and will tend to lose some low end power, the smaller ports heads will lessen the impact of lower RPM driveability and power. Also, as you mill the flow numbers will change for the worse, by how much I don't know. Hopefully some of the head guru's will step in and provide more technical information.

One other thing to keep in mind, my personal opinion only and I have been standing in the corner stating this for years. Most aftermarket heads use bronze guides. Stock rockers have a very wide wipe pattern and some even wipe on the side (front to back on the motor). As lift increases, so does the wipe pattern. Couple this with higher spring forces and I think guide wear will be accelerated. The stock rockers work fine for stock lift (lower lift results in narrower wipe) and stock forces (90 on the seat for Z06 springs). Increasing both, in my opinion, will increase bronze guide wear. So I would consider roller rockers in your plans as well.

 

They don't. I swapped 59cc Patriot LS6 Style Stage II's for 59cc AFR's and I'm happy with the results. Much better low/midrange due to the AFR's smaller runner and resulting increase in the velocity of the air coming in. Its not just about manufacturer's flow claims.

 

just something for you to ponder, great flow numbers don't automatically mean lots of hp.

good luck.

 

That's a big ol' runner if the "240 runner" means 240cc. In that case, I'd definately go with the smaller cam. You're going to be leaving A LOT of low end on the table with the G5X3 and a 240cc runner. My Patriot heads had a big runner and coupled with the G5X2 that's in the car now, they caused the engine to have an almost "VTEC" type feel as the power came on around 4200rpm. The dyno sheet confirmed how it felt as well. Low on power and then jumping up to expected levels above 4k rpm.

That's why I ended up going with the AFR's and that's also why I'll be swapping the cam out for AFR's 224/228 cam. I don't like having to spin to 6800rpm to make power, but that's just me.

 

Personally, I'd stay away from those LPE heads like the plague. Those runners had to be hogged out big time to reach those flow numbers.

 

which is fine ... if you dont mind all you power from 3500+ *caugh* dyno queen.

 

Most road race / track days, 3rd gear out of corners up to redline, shift 4th up to redline, slam on the brakes downshift 3rd 2nd and do it all over again

The cam that is most used with these heads are the GMPP Cup cam 239/251 570/570 106

I got the heads slightly used so I am by no means obligated to put them on.

Thanks for the input

dyno queen? never need the 5200 -6800 hp and 2200-4800 tq monster

 

just bustin' yer chops.

 

If I cant take a joke once in a while, I need to get off the forum.

 

Texas Speed PRC LS6 Stage 2.5 heads 64.5cc, 2.04 1.575 valves, 237cc ports...


Lift-------------------.100 .200 .300 .400 .500 .600 .625

PRC Stage 2.5 (Intake) 75 151 209 260 293 315 318
PRC Stage 2.5 (Exhaust) 66 124 160 194 217 227 234

 

I dont have time to get into a long winded post but in the end it would read something like this....comparing advertised flow numbers is a HUGE waste of time. The stuff isn't even tested on the same type of equipment. Its like trying to compare dyno numbers without a correction factor for altitude. Different benches of the same brand can read differently....throw in the fact some of the listed companies above dont test on the same equipment and it really skews the results. Plus the reality of advertising is it's just that....advertising. Some vendors are much closer to their advertised numbers in the real world than others.

Look at who's heads produce the most consistant results regardless of shop or installer....truly independent numbers from various sources. Do that and your search of "whos' heads are best" will become a much simpler task leaving you with far fewer options to choose from and further investigate.

Tony

PS....Then throw customer service and ease of install in the mix after you narrow the choices down based on performance.

 

little tiny tangent here but you guys may know this...what are the main shortcomings of the LS6 heads on the C5 Z06?

thanks!

 

In short talk to a reputable engine builder. Tell them what you want your car to do. Then go from there

 

Do you have dyno numbers for the two heads by any chance? With the larger intake runners on the PP heads I would expect some sacrifice in the lower rpm range. However, with the small combustion chamber size of the PP head and similar flow characteristics I would expect similar results (if not better) at higher RPM. I do realize that PP welds up the chamber to achieve this so I'm not sure what effect this will have but a point of squeeze has to count for something IMO.

AFR 205cc 66cc combustion chamber
Valve Lift Intake Exhaust
.200 140 112
.300 200 170
.400 251 203
.500 281 221
.550 292 226

Patriot Performance Stage II 59cc combustion
Valve Lift Intake Exhaust
.200 140 124
.300 202 160
.400 244 196
.500 280 220
.550 291 226

 

Can anybody comment on the importance of exhaust flow? Most of the conversations I've seen or participated in seem to center around intake runner size and flow as well as combustion chamber size. Obviously exhaust flow does matter as I would imagine the more efficently the piston can push the spent gases out of the chamber the better but how do real numbers translate into real horsepower? Take, for example, the AFR and the ETP heads. Both are well respected but from what I've heard the ETP head is the head of choice for big hp gains. However, the ETP heads flow significantly less on the exhaust side than do the AFR heads. Is this an example of the "law of diminishing returns?" That is, is this a case that at some point an increase of exhaust flow has less and less of an impact on overall performance within a certain RPM range? I would imagine this is the case of intake flow as well but is it more prevalent in exhaust flow?

AFR 205cc 66cc combustion chamber
Valve Lift Intake Exhaust
.200 140 112
.300 200 170
.400 251 203
.500 281 221
.550 292 226

ETP 215cc 11 degree casts 62cc combustion chamber
Valve Lift Intake Exhaust
.200 152 106
.300 219 152
.400 266 190
.500 301 204
.550 312 208