Head debate please, I got some flow numbers

V

V8Supercoupe

Registered User
Well, I picked up some heads that were said to have been worked, but there is a slight bit of confusion on my end. I have brought them to a reputable gentleman who flowed them and he has given me some options, but I could really use some advice from you guys. Especially Dave, Dave, Damon, the usual argumentitive controversial bunch! :D

To start:

Lift/intake/exh.
200- 74 - 86
300- 96 - 123
400- 112- 158
500- 124 - 183
600- 146 - 198

Now the confusion. Based on Coy's site my intake side is flowing less than stock? How the hell can that be? I guess it could be a botched port job. :rolleyes:
Onto the advice needed. I talked to this gentleman about what he could do.

Our conversation went from big this and big that to actually talking more about what the air was going to do while entering and exiting. He went on to talk about the exhaust end and how bad it is. He leaned heavily away from welding it and reshaping, although he didn't deny it could be a decent idea, I guess he was just thinking that unless your going for every drop of HP, it's not worth it. The valves he was saying were not too good due to their shape and could be improved upon using Chevy style valves.(I guess they are close to our application) Anyhow, Makes sense to me.
I guess I am trying to get a feel for what I should do. Some of you guys are turning 220-ish intake and 220-ish exhaust and the way he is talking I am not thinking I will get close to that if he does the work. I suppose I am naive, although I do trust the guy, he gives me absolutley no reason to doubt him. The work he has done for others is top knotch, so my gut says to go for the work he wants to do.
Do you guys have any recommendations on what to ask for? What to look for, or how I should have something done?

Skip
 
When I did the work to my heads, I was contemplating having the heads flowed; but I found by reading here, that most shops don't have the proper bore size to correctly flow a set of our heads. They can "rig something up" but its only good for future reference on the same bench, with identical
"rigging" i.e. you would have to have flowed them im stock form prior to the porting to know what the relative improvemnets were...

Somewhere I read Coy Miller was the only shop that had the proper setup, but I'd think someone else has our 3.8 setup somewhere...


So if there was supposedly "port work" done to them you might want to consider getting another set of stockers to compare, contrast, and possibly flow again...

I didn't flow mine becasue I would have had to pay for them to be flowed twice, and the numbers wouldn;t mean that much anyways...

The real numbers are on those little little slips they hand out at the end of the 1/4 :D
 
Well I suppose. The numbers seem real whacky to me. I know this particular person probably isn't setup exactly the way he should be for our heads, but I suppose it's a starting point anyway.
Even if he isn't setup for our heads, it's still is odd that the exhaust is so much higher than the intake. He wants(I want) him to report/polish and drop all new, larger valves. He is obviously concerned more about airflow pattern then he is size of the portwork. I suppose that's good, and I know he is going to hog them out a bit more, I just don't know how much more of a dramtic effect it will make.
 
Well I've been suggested to maintain the stock intake valve, and only enarge the exhasut valve. So this is the route I went. I got 1.625 SBC exhaust valves in the heads at the shop now..

The intake is already gonna be compressed, and even (effectively) more so in my case as I'm gonna be hitting the bottle. I'm not sure what a rule of thumb I:E ratio is for an N/A heads is gonna be, but the ratio has got to be differnet in a FI application, particularly at higher boost levels and N2O...
 
Well, that's brings up a good point considering I am wanting(wanting) to run a higher than normal boost level and run a small shot to cool the intake charge.
 
I believe that the best you can do with our heads is a I/E ratio of 93%.These #'s are from Coy Miller Stage II heads with a 1.62" valve.Even if the shop did not have the proper diameter pipe to flow thru,you should have seen better than stock #'s.That is why it's important to see flow #'s when you get a set of heads ported,so you can be there to see the #'s not just be quoted them(and take their word for it).
 
Those exhaust flow numbers are very good for No welding (Prob about as good as you can get )

I couldnt even guess why the flow numbers are so low for Intake side
The intake Just requires some reshaping to acheive decent numbers


Those numbers do Indeed seem a lil wacky to me also
 
Very easy...

Very easy to screw up porting....I will say though that those intake numbers are VERY LOW>>>>>

I feel that the flow bench they were using was not set up properly.

The exhaust numbers are impressive for not doing any other work besides porting and blending.
 
Well, I have no doubt this guy can neaten things up, I just don't want to get talked into something less then what I could get for the money.
I always hear the stories about the guys who are real good with the V8 cars but seem to apply that same knowledge to a 6. I have heard a lot of people say that just doesn't work. When it comes to heads I don't know what the difference is, you'd think the basic concept is all the same.
 
A lot of people post things of which they know very little. I'd take some of the things you read on this site with a grain of salt. There is a short list of people on here whose opinions I personally trust when it comes to headwork.

Regarding the heads in question, unless the heads received an absolute hack job, the intakes will flow better than the exhausts. Perhaps someone got the numbers mixed up?

Also, Coy is not the only one with the proper equipment to flow test our heads, but regardless flow numbers are just that. Numbers.

Good flowing heads can be generated at any shop with a decent porter who has flowed heads before and knows what a good port/chamber looks like. It is not necessary to try to achieve Bob Steigemeier flow numbers anyway. Marc Petillo proved that at the SC shootout this year with heads that I ported for him with no flow numbers or even any verifieable "experience".

His car made 290rwhp and ran 104mph in the 1/4 on an early style blower that I also ported for him in my garage. My only point in saying any of that is that "uber cool" heads are not going to make the difference between making power and not. I could go on and on but you'd get tired of hearing about it. :p

Regarding valve sizes, you are limited to the diameter of the stock seats which means that if your machinist is worth his metric weight he should be able to tell you what sizes to run just as quickly as he can pop a valve out and look at it.

Oh, and 1.625 E is way too big. ;)
 
I could go on and on but you'd get tired of hearing about it.
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I doubt it, I am more likely to talk your ear off about it.....
er..but I guess that won't happen cause I can't get someone to call me! :p :D

This guy did rattle off this and that, I don't understand whats what, but he rolled off some chevy valves that he said would open things up. How much I don't know....This isi one of these deals where the guy has a good reputation, but I am trying to apply what I have heard and not what I know.

I'll at least be honest about that.
 
XR7 Dave said:
It is not necessary to try to achieve Bob Steigemeier flow numbers anyway. Marc Petillo proved that at the SC shootout this year with heads that I ported for him with no flow numbers or even any verifieable "experience".

His car made 290rwhp and ran 104mph in the 1/4 on an early style blower that I also ported for him in my garage. ;)
Click to expand...

David,
Did you change the valves on those heads you ported? I'm not trying to get any trade secrets, but an trying to better uderstanding just like others. The machinist that I'm going to use for my head project is very familiar with Ford heads and has produced exhaust flow numbers close to Stieg heads without the welding. I just want to know if I can achieve good power numbers by re-working the stock valves, or if I should go a bit larger. I don't want to hijack the thread here, but I do think that this is relavant. Although my power level goals may be different, I think that we can all benefit from additional information.

Basically what I'm looking for is 1)what type of "generalized" power levels can we expect from porting/reworking the bowls, runners etc with a 3 and 5-7 angle vlave job on the stock valves?

2) What type of power levels can we expect by going to a larger set of valves?

Obviously, cam selection would play a very large role in determining power levels of different types of heads. I would request known combinations that you have tuned, worked on, etc so we have real world type information, not just numbers from a flow machine. I think that would give everyone looking at this some information as to guide them to making better decisions based upon power goals and current applications. Thanks.
 
With the experience I had with porting my own heads, all the humps, rigidities, and all other casting marks being removed along with gasket matching helps alot more than you think.

A ported, stock valve, nonwelded head would be good enough for 12's. Port shape, cross sectional area, turn radius, and valve size are all relavent to eachother in terms of flow/velocity. In my experience in the porting of high performance heads, whether its pro stock, SuperStock, and even stock, flow numbers had their biggest jump in flow numbers with valve size.

The valve seat angles are very important also. In my superstocker I picked up 22cfm on stock sized valve going from 30 degrees to 58 (highest valve angle recommended to go to on any head) and unschrouding the valves.

Anyway, back to the SC heads, the exhaust port talk is all wack, nonetheless, overrated. All thats really needed is to clean up the casting marks and polish it. The port has a really short turn and the length of valve to flange is very short. Just manipulate this with headers. If i'm not mistaken, I remember a while back reading Kevin L. has stock exhaust ports.
 
XR7 Dave said:
Oh, and 1.625 E is way too big. ;)
Click to expand...

You mentioned this to me at some point before, and never did elaborate :mad:

I've been worrying about it now, but its too late, the new seats have already been installed....

Why do you say that the 1.625 is too big :confused: :confused: :confused:
 
007_SuperCoupe said:
David,
Did you change the valves on those heads you ported? I'm not trying to get any trade secrets, but an trying to better uderstanding just like others. The machinist that I'm going to use for my head project is very familiar with Ford heads and has produced exhaust flow numbers close to Stieg heads without the welding. I just want to know if I can achieve good power numbers by re-working the stock valves, or if I should go a bit larger. I don't want to hijack the thread here, but I do think that this is relavant. Although my power level goals may be different, I think that we can all benefit from additional information.

Basically what I'm looking for is 1)what type of "generalized" power levels can we expect from porting/reworking the bowls, runners etc with a 3 and 5-7 angle vlave job on the stock valves?

2) What type of power levels can we expect by going to a larger set of valves?

Obviously, cam selection would play a very large role in determining power levels of different types of heads. I would request known combinations that you have tuned, worked on, etc so we have real world type information, not just numbers from a flow machine. I think that would give everyone looking at this some information as to guide them to making better decisions based upon power goals and current applications. Thanks.
Click to expand...

Marc's heads have larger valves. There are no trade secrets here. We used 1.88 intakes and 1.50 exhausts and then the seats are formed with a custom selected 3 angle Serdi cutter. Then we add the appropriate hardware on top.

I am not a fan of stock valves at all. Not because they are so bad, but they prevent the use of good valve springs which I feel are necessary for proper operation under high boost conditions.

In our world power comes primarily from boost. The ability to use boost is the key to making power.

Ya, I'm rambling here.

Anyway, a qualified systems approach is the best way to achieve a goal. Select your parts based on solid theory and make sure that they all match up. The end result will make it difficult to say exactly where the power came from, it will just be there. All too often people hone in on one particular part of a successful combination without buying into the whole program.

Kevin's car is an excellent example of a successful combination. No one single part of his car is responsible for his success. It's his careful application of parts which work together that has gotten him where he is.
 
sizemoremk said:
You mentioned this to me at some point before, and never did elaborate :mad:

I've been worrying about it now, but its too late, the new seats have already been installed....

Why do you say that the 1.625 is too big :confused: :confused: :confused:
Click to expand...

Because the port itself is the choke point, not the valve, and so a bigger valve is only going to create problems with shrouding.

The stock seats were quite adequate.
 
not sure if this has been said... but flow benches will pretty much always give different #'s bench to bench. You will rarely (if ever) find 2 shops that will have benches that will get the same #'s as each other.

For example.. the heads on my company race car from TEA flow I398/E305, on another bench they were only I374/E288, and on another they were only I380/E295. Granted these are just peak numbers which hardly mean ~~~~, and across the board they were all relatively close..but they were still off by 10-15cfm on each bench at .800" lift.

i had a set of TFS-R heads done by TEA and the flow sheet that came back with them were I368/E277 @ .700", but on another bench they only made I345/250 @ .700".. and across the board every number was off by about 12-13cfm.
 
XR7 Dave said:
Because the port itself is the choke point, not the valve, and so a bigger valve is only going to create problems with shrouding.

The stock seats were quite adequate.
Click to expand...


Damnit, you're gonna force me to flow these heads :p
 
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