Had my GTP heads flown....
Registered User
Joined: Oct 2000
Posts: 786
From: Charlotte, NC
Good is honest, nomatter what they end up flowing. IMHO anyway.. not everyone needs a killer set of heads.
For what it's worth, the results we've gotten have been the same as Ellis' and Lloyd, regarding the stuff in question. And they arent $1800, theyre $2400+core.
Grip, benches are different, but using the same techniques with the same procedure and calibrated equipment should garner results within 1.5%.
You guys get lied to so much it's disgusting. The worst thing is that people don't know any better b/c they've no frame of reference.. they bolt it on, it feels faster, so they must have been telling the truth. Unfortunate.
For what it's worth, the results we've gotten have been the same as Ellis' and Lloyd, regarding the stuff in question. And they arent $1800, theyre $2400+core.
Grip, benches are different, but using the same techniques with the same procedure and calibrated equipment should garner results within 1.5%.
You guys get lied to so much it's disgusting. The worst thing is that people don't know any better b/c they've no frame of reference.. they bolt it on, it feels faster, so they must have been telling the truth. Unfortunate.
Registered User
Joined: Jul 1999
Posts: 128
From: Tx
Gripenfelter,
Flow bench error, from bench to bench should not exceed +or- 1%.
Ryan,
A port flowing 255-260cfm is not necessarily a bad port. The flow numbers for a well developed port in the 190cc range would look something like this:
.200 - 140
.300 - 200
.400 - 250
.500 - 255
.600 - 260
Now compare those flow #'s to the flow numbers NightTrain listed and you will see the real difference.
I posted a thread here a couple months ago on how to make real-world comparisons of cylinder head flow numbers. From there you'll find a better method of comparisons.
Yes, these heads need quite a bit of work. Nothing your engine builder should be able to remedy though. Not that that makes any excuses for the poor quality of work you recieved.
edit: someone deleted their post while I was typing some of this. Unfortunately I don't type very fast but the info is still relevent to this discussion so I'll leave it.
Take care
Flow bench error, from bench to bench should not exceed +or- 1%.
Ryan,
A port flowing 255-260cfm is not necessarily a bad port. The flow numbers for a well developed port in the 190cc range would look something like this:
.200 - 140
.300 - 200
.400 - 250
.500 - 255
.600 - 260
Now compare those flow #'s to the flow numbers NightTrain listed and you will see the real difference.
I posted a thread here a couple months ago on how to make real-world comparisons of cylinder head flow numbers. From there you'll find a better method of comparisons.
Yes, these heads need quite a bit of work. Nothing your engine builder should be able to remedy though. Not that that makes any excuses for the poor quality of work you recieved.
edit: someone deleted their post while I was typing some of this. Unfortunately I don't type very fast but the info is still relevent to this discussion so I'll leave it.
Take care
Last edited by Mr. Horsepower; Feb 1, 2003 at 04:00 PM.
Registered User
Joined: Jul 1999
Posts: 128
From: Tx
Originally posted by SkarodoM
Good is honest, nomatter what they end up flowing. IMHO anyway.. not everyone needs a killer set of heads.
Good is honest, nomatter what they end up flowing. IMHO anyway.. not everyone needs a killer set of heads.
Take care
Registered User
Joined: Dec 1999
Posts: 2,248
From: Houston, TX
Originally posted by Mr. Horsepower
Gripenfelter,
Flow bench error, from bench to bench should not exceed +or- 1%.
Ryan,
A port flowing 255-260cfm is not necessarily a bad port. The flow numbers for a well developed port in the 190cc range would look something like this:
.200 - 140
.300 - 200
.400 - 250
.500 - 255
.600 - 260
Now compare those flow #'s to the flow numbers NightTrain listed and you will see the real difference.
I posted a thread here a couple months ago on how to make real-world comparisons of cylinder head flow numbers. From there you'll find a better method of comparisons.
Yes, these heads need quite a bit of work. Nothing your engine builder should be able to remedy though. Not that that makes any excuses for the poor quality of work you recieved.
Take care
Gripenfelter,
Flow bench error, from bench to bench should not exceed +or- 1%.
Ryan,
A port flowing 255-260cfm is not necessarily a bad port. The flow numbers for a well developed port in the 190cc range would look something like this:
.200 - 140
.300 - 200
.400 - 250
.500 - 255
.600 - 260
Now compare those flow #'s to the flow numbers NightTrain listed and you will see the real difference.
I posted a thread here a couple months ago on how to make real-world comparisons of cylinder head flow numbers. From there you'll find a better method of comparisons.
Yes, these heads need quite a bit of work. Nothing your engine builder should be able to remedy though. Not that that makes any excuses for the poor quality of work you recieved.
Take care
I will post the info for others:
This is a tricky subject for sure. Simply due to the fact that there are so many variables at work here... test to test. Let me outline some of this before we get into our comparisons.
1) Flowbench calibration: Data is only useful for comparison when performed on an accurately calibrated flowbench.
2) Geometry: Alignment of the head with the bore-fixture must simulate the realationship the bore sees in the head when it is installed on it's dowels. This is an easy way to fluff up flow #s on a big valve high-lift head running on a small cylinder bore... move the intake valve away from the bore and you have a little less shrouding. Seen guys do it on purpose.
3) Need atmospheric conditions for data interpretation.
4) Need accurate lift readings
5) Was the head flown with the valves it will be using. You can also fluff up the numbers with a specially prepared valve. So you ask, "Why not run a valve with that geometry?" Because it wouldn't last a day under real operating conditions.
6) The head should be flown on a bore-fixture similiar to the actual bore of the application. This will have a greater affect on the big-valve high-lift heads than the smaller ones. Either way, look at the bore fixture diameter when making comparisons.
7) The head should be flown with a radiused inlet and an exhaust extension approximately 6" long. This will simulate flow more accurately thwarting shear effects.
That sums the biggest part of it up pretty well... I'm sure I'll want to add more to this the more I think on it but this should cover the bulk.
Now to comparisons... I haven't really studied this "Flow index" theory much... everyone has there little way of doing this. I was taught a method by David Reher when I worked at RMRE which I really like to use... it's somewhat quick and easy and gives a good idea of what we're looking for in a cylinder head.... area under the curve. Peak is nice but AUC is what wins races guys. So, let's cut to the chase.
I'll use two examples of similiar heads and keep it very simple for now...
The Brodix -10 (210 cc) in full port form #'s according to Brodix. 2.08/1.6 valves. (I'm only going to work the intake #'s here so we all get the basic idea)
Intake
@.200 --- 147
@.300 --- 205
@.400 --- 254
@.500 --- 287
@.600 --- 303
@.650 --- 305
@.700 --- 307
The AFR 210 cc "Racing Head", Competition Package (2.08/1.6 valves)
Intake
@.200 --- 138
@.300 --- 201
@.400 --- 247
@.500 --- 276
@.600 --- 288
@.650 --- 293
@.700 --- 297
Notice we used the same number of lift points. In practice, and in considering the application to be a daily driven street car, I wouldn't really use lift figures beyond the cam's maximum lift. We all know by now that the valve spends more time at low to mid lift... Reher use to say, "One time to peak and twice through mid lift".
For this example we'll use every lift point.
Now, here's the formula for calculating area under the curve (AUC):
AUC = .050 x (LP1 + LP1 + LP2 + LP2 + LP3 + LP3 + LP4 + LP4 + LP5 + LP5 + LP6 + LP6 + LP7 + LP7 + LP8)
May not make much sense in terms of the order of operations but it is easier for people to understane when written like so:
AUC = .050 x (LP1 + (LP1 + LP2) + (LP2 + LP3) + (LP3 + LP4) + (LP4 + LP5) + (LP5 + LP6) + (LP6 + LP7) + (LP7 + LP8))
So, work through the lift points of the Brodix -10 and you get a AUC value of 166, do the same for the AFR and we get 159
Brod -10 = 166
AFR 210 = 159
Notice we used all the lift points in this example. Now let's look at the Brodix Smokey Yunick head as prepared by Weld Tech. For this example we're only going to look at #'s to .500 lift. Our comparison will be to the AFR 210. Important to remember here is that the AFR 210 is cast to 210 ccs, it is then worked to flow what it does in it's "Competition Package" form... in other words, the port volume is greater than 210 ccs in finished form.
The Brodix SY head on the other hand is finished by Weld Tech to 187 ccs and uses a smaller 2.02/1.6 valve combination. Now let's look at the numbers...
Brodix SY Intake:
@.200 --- 142
@.300 --- 204
@.400 --- 251
@.500 --- 254
AFR 210 Intake:
@.200 --- 138
@.300 --- 201
@.400 --- 247
@.500 --- 276
Well the AFR won, it's got the bigger peak # right? Do the math....
Brodix SY:
AUC = 72.4
AFR 210:
AUC = 72.4
(BTW- I went through the math real quick so please double check)
A little more to flow numbers than peak. The SY appears to be at a disadvantage, it has a smaller port volume and smaller valves, yet it would walk off and leave the AFR 210 in similiar applications.... In this case let's say a 3 speed auto car that weight 3700 lbs, using a mild cam and using a numerically low rear cog ratio.
This is only a smidge, but it should broaden your understanding of what really matters when looking at cylinder heads. Didn't directly answer your question but hopefully you got a little more bang for your buck with this explanation.
1) Flowbench calibration: Data is only useful for comparison when performed on an accurately calibrated flowbench.
2) Geometry: Alignment of the head with the bore-fixture must simulate the realationship the bore sees in the head when it is installed on it's dowels. This is an easy way to fluff up flow #s on a big valve high-lift head running on a small cylinder bore... move the intake valve away from the bore and you have a little less shrouding. Seen guys do it on purpose.
3) Need atmospheric conditions for data interpretation.
4) Need accurate lift readings
5) Was the head flown with the valves it will be using. You can also fluff up the numbers with a specially prepared valve. So you ask, "Why not run a valve with that geometry?" Because it wouldn't last a day under real operating conditions.
6) The head should be flown on a bore-fixture similiar to the actual bore of the application. This will have a greater affect on the big-valve high-lift heads than the smaller ones. Either way, look at the bore fixture diameter when making comparisons.
7) The head should be flown with a radiused inlet and an exhaust extension approximately 6" long. This will simulate flow more accurately thwarting shear effects.
That sums the biggest part of it up pretty well... I'm sure I'll want to add more to this the more I think on it but this should cover the bulk.
Now to comparisons... I haven't really studied this "Flow index" theory much... everyone has there little way of doing this. I was taught a method by David Reher when I worked at RMRE which I really like to use... it's somewhat quick and easy and gives a good idea of what we're looking for in a cylinder head.... area under the curve. Peak is nice but AUC is what wins races guys. So, let's cut to the chase.
I'll use two examples of similiar heads and keep it very simple for now...
The Brodix -10 (210 cc) in full port form #'s according to Brodix. 2.08/1.6 valves. (I'm only going to work the intake #'s here so we all get the basic idea)
Intake
@.200 --- 147
@.300 --- 205
@.400 --- 254
@.500 --- 287
@.600 --- 303
@.650 --- 305
@.700 --- 307
The AFR 210 cc "Racing Head", Competition Package (2.08/1.6 valves)
Intake
@.200 --- 138
@.300 --- 201
@.400 --- 247
@.500 --- 276
@.600 --- 288
@.650 --- 293
@.700 --- 297
Notice we used the same number of lift points. In practice, and in considering the application to be a daily driven street car, I wouldn't really use lift figures beyond the cam's maximum lift. We all know by now that the valve spends more time at low to mid lift... Reher use to say, "One time to peak and twice through mid lift".
For this example we'll use every lift point.
Now, here's the formula for calculating area under the curve (AUC):
AUC = .050 x (LP1 + LP1 + LP2 + LP2 + LP3 + LP3 + LP4 + LP4 + LP5 + LP5 + LP6 + LP6 + LP7 + LP7 + LP8)
May not make much sense in terms of the order of operations but it is easier for people to understane when written like so:
AUC = .050 x (LP1 + (LP1 + LP2) + (LP2 + LP3) + (LP3 + LP4) + (LP4 + LP5) + (LP5 + LP6) + (LP6 + LP7) + (LP7 + LP8))
So, work through the lift points of the Brodix -10 and you get a AUC value of 166, do the same for the AFR and we get 159
Brod -10 = 166
AFR 210 = 159
Notice we used all the lift points in this example. Now let's look at the Brodix Smokey Yunick head as prepared by Weld Tech. For this example we're only going to look at #'s to .500 lift. Our comparison will be to the AFR 210. Important to remember here is that the AFR 210 is cast to 210 ccs, it is then worked to flow what it does in it's "Competition Package" form... in other words, the port volume is greater than 210 ccs in finished form.
The Brodix SY head on the other hand is finished by Weld Tech to 187 ccs and uses a smaller 2.02/1.6 valve combination. Now let's look at the numbers...
Brodix SY Intake:
@.200 --- 142
@.300 --- 204
@.400 --- 251
@.500 --- 254
AFR 210 Intake:
@.200 --- 138
@.300 --- 201
@.400 --- 247
@.500 --- 276
Well the AFR won, it's got the bigger peak # right? Do the math....
Brodix SY:
AUC = 72.4
AFR 210:
AUC = 72.4
(BTW- I went through the math real quick so please double check)
A little more to flow numbers than peak. The SY appears to be at a disadvantage, it has a smaller port volume and smaller valves, yet it would walk off and leave the AFR 210 in similiar applications.... In this case let's say a 3 speed auto car that weight 3700 lbs, using a mild cam and using a numerically low rear cog ratio.
This is only a smidge, but it should broaden your understanding of what really matters when looking at cylinder heads. Didn't directly answer your question but hopefully you got a little more bang for your buck with this explanation.
Ryan
Registered User
Joined: Aug 2002
Posts: 1,509
From: Red Oak Texas
WOW. I am not sure why my previous post was posted 3 times.
Here is a rundown of how the heads I tested were flowed.
Intake- head was centered on bore and used a 4.155 bore and a 1/2 inch clay lip on the intake. It is not fair to compare these #'s to a head flowed with a longer radius but then again the 4.155 bore flow #'s may not compare to a 4.030 or 4.060 bore flow #'s. I am not sure how much either of these help/hurt but that is how I got THESE flow #'s that I posted.
Exhaust- no exhaust pipe was used. A pipe used here would have brought the #'s up some. Maybe 5-15 cfm????? maybe???? Phil or Chuck could probably tell us how much it is worth. If you are comparing these #'s to an exhaust flowed with a pipe the #'s COULD vary some.
The valvejob used was a pretty good flowing valvejob at high lifts. After a "touch up" port job on the exhaust they flowed 217 at .600 lift. That is about 10 cfm better than I have EVER got on a LT1 head. I am sure if the valvejob would have been more "low lift friendly" the peak #'s would have been lower.
I am not trying to talk anyone into or out of GTP heads, I just wanted everyone to know the procedure that was used when flowing the heads and getting these #'s.
NightTrain66
Here is a rundown of how the heads I tested were flowed.
Intake- head was centered on bore and used a 4.155 bore and a 1/2 inch clay lip on the intake. It is not fair to compare these #'s to a head flowed with a longer radius but then again the 4.155 bore flow #'s may not compare to a 4.030 or 4.060 bore flow #'s. I am not sure how much either of these help/hurt but that is how I got THESE flow #'s that I posted.
Exhaust- no exhaust pipe was used. A pipe used here would have brought the #'s up some. Maybe 5-15 cfm????? maybe???? Phil or Chuck could probably tell us how much it is worth. If you are comparing these #'s to an exhaust flowed with a pipe the #'s COULD vary some.
The valvejob used was a pretty good flowing valvejob at high lifts. After a "touch up" port job on the exhaust they flowed 217 at .600 lift. That is about 10 cfm better than I have EVER got on a LT1 head. I am sure if the valvejob would have been more "low lift friendly" the peak #'s would have been lower.
I am not trying to talk anyone into or out of GTP heads, I just wanted everyone to know the procedure that was used when flowing the heads and getting these #'s.
NightTrain66
Thread Starter
Registered User
Joined: Jul 2000
Posts: 2,735
From: Buffalo, NY
Whoa! I made the post and hadnt checked it in a while....
Yeah Im not all that happy with the numbers. I tried calling GTP to talk to craig but ofcourse I never got a call back. That place seems to be extremely busy. I never get any calls or emails back though....
They seem to be a great deal better than Cody's stage II on the board....
At this point Im stuck with them since my stroker is just about to be put together in the next couple weeks......They advertise 270/210 but as you can see mine didnt make that......hindsight is always 20/20 but it looks like I should have gone with someone else.
Oh well.....
Yeah Im not all that happy with the numbers. I tried calling GTP to talk to craig but ofcourse I never got a call back. That place seems to be extremely busy. I never get any calls or emails back though....
They seem to be a great deal better than Cody's stage II on the board....
At this point Im stuck with them since my stroker is just about to be put together in the next couple weeks......They advertise 270/210 but as you can see mine didnt make that......hindsight is always 20/20 but it looks like I should have gone with someone else.
Oh well.....
Registered User
Joined: Aug 2002
Posts: 1,509
From: Red Oak Texas
since you are on a time "crunch" ya might not have time for GTP to touch em up for ya but maybe you find a local porter to go in and help out those intake #'s for ya. Since Stroker has/did have the heads he could maybe do this for ya. It would be worth it in my opinion if the low and mid #'s are similar to the ones that I tested. If you get the low and mid #'s from Stroker and they seem pretty good you may just bolt em on then.
NightTrain66
NightTrain66
Registered User
Joined: Jul 1999
Posts: 3,647
From: Winnipeg, Manitoba, Canada
Flowtech heads in Winnipeg (now defunct) told me the heads they ported flowed exactly the same as another customer's that flowed 268cfm peak.
I took them to 2 other engine shops that said no more than 235cfm peak.
Needless to say I had them re-done.
Flowtech's excuse was "not all flowbenches flow the same".
I took them to 2 other engine shops that said no more than 235cfm peak.
Needless to say I had them re-done.
Flowtech's excuse was "not all flowbenches flow the same".
Registered User
Joined: Jun 2001
Posts: 872
From: "Shoulda Gotton An LS1 Racin"
Originally posted by NightTrain66
Smokin,
it may be worthwile to get them flowed at another shop and compare them to GTP's #'s.
NightTrain66
Smokin,
it may be worthwile to get them flowed at another shop and compare them to GTP's #'s.
NightTrain66
Registered User
Joined: Aug 2002
Posts: 1,509
From: Red Oak Texas
sometimes people get "better" results when they mention that the heads will be tested afterwords on another bench. Or if you flow them on another bench and tell GTP that they flowed XXX amount and you paid for XXX amount and they will be retested after GTP "touches" them up.
something to think about.
NightTrain66
something to think about.
NightTrain66