Drivetrain Heads...a discussion
First big question.
Are the bigger valves necessary or just better valves and optimized flow?
Simplification statement warning:
Smaller runner cross section= better low end performance, quicker throttle response, etc. Sacrifice breathing at high rpm.
Larger runner cross section = Improved top end performance. Sacrifice low rpm response.
The big hole I see in this is you can't seriously discuss head performance without, at a minimum, speccing the cam.
So do we bracket this discussion by limiting it to a stock spec cam or do we open it up to the far wider discussion of including cam specs.
Inevitably intake and exhaust design will come into play.
So? What are the parameters? Do we care?
Are the bigger valves necessary or just better valves and optimized flow?
Simplification statement warning:
Smaller runner cross section= better low end performance, quicker throttle response, etc. Sacrifice breathing at high rpm.
Larger runner cross section = Improved top end performance. Sacrifice low rpm response.
The big hole I see in this is you can't seriously discuss head performance without, at a minimum, speccing the cam.
So do we bracket this discussion by limiting it to a stock spec cam or do we open it up to the far wider discussion of including cam specs.
Inevitably intake and exhaust design will come into play.
So? What are the parameters? Do we care?
Temporarily Banned
Joined: Oct 2002
Posts: 3,382
Likes: 2
From: Denver
"Thanks for the post Randy..... does a head of this nature benefit an otherwise stock car..... or do you recommend header, pullley etc..... I have heard some say oversize valves can kill torque..... is there a "sweet spot where the head makes more sense...is it a good first mod (unlikely it would be someone's first mod but would it be a good choice?)" - SpiderX
Good question. It certainly would be a better idea to do the pulley before the head, but good flow - quality of the flow, not just CFM - is going to benefit any motor. Why isn't it like that stock then, you may ask. Time and money. It takes quite a bit of time, which of course equals money, to optimize the flow.
Can you lose torque from larger valves - absolutely. If you port and cam correctly though, you should be able to take advantage. Take a look for example at the flow numbers on the exhaust side. You will notice that with 1mm larger valves alone, the CFM drops initially compared to stock - but then look at the ported numbers. It is very important to look at the balance - intake/exhaust ratios, flow capacity, CC shape, flow quality, etc.
The head I am discussing is the one I make for most cars. If you called me to tell me that you were building a track-only racer, I could care less what happens below 4500 RPM, and I would port accordingly. That's not what 98% of folks are doing though, so I am covering data relating to the head most appropriate for this thread.
Hope that helps!
Randy
Good question. It certainly would be a better idea to do the pulley before the head, but good flow - quality of the flow, not just CFM - is going to benefit any motor. Why isn't it like that stock then, you may ask. Time and money. It takes quite a bit of time, which of course equals money, to optimize the flow.
Can you lose torque from larger valves - absolutely. If you port and cam correctly though, you should be able to take advantage. Take a look for example at the flow numbers on the exhaust side. You will notice that with 1mm larger valves alone, the CFM drops initially compared to stock - but then look at the ported numbers. It is very important to look at the balance - intake/exhaust ratios, flow capacity, CC shape, flow quality, etc.
The head I am discussing is the one I make for most cars. If you called me to tell me that you were building a track-only racer, I could care less what happens below 4500 RPM, and I would port accordingly. That's not what 98% of folks are doing though, so I am covering data relating to the head most appropriate for this thread.
Hope that helps!
Randy
"Thanks for the post Randy..... does a head of this nature benefit an otherwise stock car..... or do you recommend header, pullley etc..... I have heard some say oversize valves can kill torque..... is there a "sweet spot where the head makes more sense...is it a good first mod (unlikely it would be someone's first mod but would it be a good choice?)" - SpiderX
Good question. It certainly would be a better idea to do the pulley before the head, but good flow - quality of the flow, not just CFM - is going to benefit any motor. Why isn't it like that stock then, you may ask. Time and money. It takes quite a bit of time, which of course equals money, to optimize the flow.
Can you lose torque from larger valves - absolutely. If you port and cam correctly though, you should be able to take advantage. Take a look for example at the flow numbers on the exhaust side. You will notice that with 1mm larger valves alone, the CFM drops initially compared to stock - but then look at the ported numbers. It is very important to look at the balance - intake/exhaust ratios, flow capacity, CC shape, flow quality, etc.
The head I am discussing is the one I make for most cars. If you called me to tell me that you were building a track-only racer, I could care less what happens below 4500 RPM, and I would port accordingly. That's not what 98% of folks are doing though, so I am covering data relating to the head most appropriate for this thread.
Hope that helps!
Randy
Good question. It certainly would be a better idea to do the pulley before the head, but good flow - quality of the flow, not just CFM - is going to benefit any motor. Why isn't it like that stock then, you may ask. Time and money. It takes quite a bit of time, which of course equals money, to optimize the flow.
Can you lose torque from larger valves - absolutely. If you port and cam correctly though, you should be able to take advantage. Take a look for example at the flow numbers on the exhaust side. You will notice that with 1mm larger valves alone, the CFM drops initially compared to stock - but then look at the ported numbers. It is very important to look at the balance - intake/exhaust ratios, flow capacity, CC shape, flow quality, etc.
The head I am discussing is the one I make for most cars. If you called me to tell me that you were building a track-only racer, I could care less what happens below 4500 RPM, and I would port accordingly. That's not what 98% of folks are doing though, so I am covering data relating to the head most appropriate for this thread.
Hope that helps!
Randy
pug poo picker-upper
Joined: Jun 2002
Posts: 9,803
Likes: 30
From: California
Please Read
This thread has just had a major clean-up of a lot of off topic discussion, there may be more clean-up left to do.
There has also been a problem in this thread with members showing other members respect. This is the second time today I have had to address this.
If respect and on topic discussion can not be restored in this thread it can easily be closed and I can start issueing strikes as laid out in the NAM Site Guidelines.
This thread has just had a major clean-up of a lot of off topic discussion, there may be more clean-up left to do.
There has also been a problem in this thread with members showing other members respect. This is the second time today I have had to address this.
If respect and on topic discussion can not be restored in this thread it can easily be closed and I can start issueing strikes as laid out in the NAM Site Guidelines.
Banned
Joined: Jul 2004
Posts: 1,848
Likes: 1
From: City of Angels, Cali
Yes, I was actually quite disgusted myself by the manner in which some people posted. Thank you Dave for clearing all that up.
btw... I posted here on how to get out of a spin, but that may have accidentally got deleted also, so don't blame me if one day you guys go into a spin and can't recover, because I posted the how to here, it could save your life.
p.s. If you see my Camel going into a spin, don't panic, it's actually controlled, I did it on purpose to make the enemy Scout think he shot me down.
p.p.s. (to keep this post on topic) From Randy's pics and posts, it looks to me he knows what he is doing. Quite frankly, I dont see how anyone could go with anyone else's head.
btw... I posted here on how to get out of a spin, but that may have accidentally got deleted also, so don't blame me if one day you guys go into a spin and can't recover, because I posted the how to here, it could save your life.
p.s. If you see my Camel going into a spin, don't panic, it's actually controlled, I did it on purpose to make the enemy Scout think he shot me down.
p.p.s. (to keep this post on topic) From Randy's pics and posts, it looks to me he knows what he is doing. Quite frankly, I dont see how anyone could go with anyone else's head.
4th Gear
Joined: Nov 2004
Posts: 345
Likes: 0
From: Los Angeles
Thanks Randy. Maybe the Nuts are gonna give me head at my birthday party tomorrow - (3PM SHARP! Right Camelpilot?) but they're cheap so I guess I'll have to save my pennies to get head from you myself.
...and yes! artist formerly known as DiD - I'm talking cylinder head!
...and yes! artist formerly known as DiD - I'm talking cylinder head!
Banned
iTrader: (1)
Joined: Feb 2005
Posts: 4,054
Likes: 0
From: As far away from Florida as I can get.
Wow, it's like I never posted. 
But, I would try a new head, except my wife won't let me. She says I've already spent enough money. So I will have to stick with the head I have. The JCW one.
Yes Dave. I am talking about the cylinder head.
But, I would try a new head, except my wife won't let me. She says I've already spent enough money. So I will have to stick with the head I have. The JCW one. Yes Dave. I am talking about the cylinder head.
Banned
Joined: Jul 2004
Posts: 1,848
Likes: 1
From: City of Angels, Cali
Something just occured to me.....
Do you think the reason why people want Randy's head on a platter is because they hear good things about "Randy's head", but don't know that people are actually talking about his CYLINDER HEAD?????
Maybe if we clear that up people will be NICE to Randy from now on??.
Definitely, Hopefully, Maybe.
Do you think the reason why people want Randy's head on a platter is because they hear good things about "Randy's head", but don't know that people are actually talking about his CYLINDER HEAD?????
Maybe if we clear that up people will be NICE to Randy from now on??.
Definitely, Hopefully, Maybe.
6th Gear
Joined: Sep 2002
Posts: 2,196
Likes: 0
From: Hampton, VA
it's all about the end result yes? so whatever flows better i would think. this is the heads job right? plus keeping the compression in and all the parts going back down. back in the day this wasdone with bigger valves ,three angle valve jobs , higher lift cams with adjustible timing gears for custom overlap . it's an end result that can be attained it seems several ways . i can't imagine bigger valves if not much heavier being a problem with the stock cam they're probably good. and float wouldn't be a worry as with a high rise. who knows but the guys with the flow benches ?:impatient :impatient :impatient
That was that there isn't 1 perfect flow for every condition. It needs to be clear when anyone posts, be it vendor or others, is the how, when, where this increased flow does the most good. A head that flows 25% over stock and has a useful rpm range of 5-8K rpm is worthless to me yet very valuable to someone else. That is my interest in this thread.
I never took Bob's question as an inquiry into specifics but more along the lines of what works for the MINI.
The one consensus so far is the exhaust side sucks. A ton can be learned and taught without specifics. Don't care what valve angle(s) may have worked just that there is an improvement to be made over stock.
Without giving away a single detail any vendor can prove the effectiveness of their head/cam combo. They can also demoinstrate how it is most effective.
Ideally I want 3500 to 5500 rpms to be my fat zone. If I start wheezing over 6K I could care less. I autocross, pull out into busy urban traffic and onto freeways. If I don't have beef until 5K I might as well be walking or driving my minivan
Someone show me a combo that does that and I'll buy it.
This is why the M62 is so interesting to me. Get me 210lbs/ft @ the wheels @ ~5200
Edit:
Wrote this before I saw Randy's post. We've discussed this same thing before. It's all doable. What needs to be defined though is if venfors are doing a one size fits all for the price or building a more targeted solution.
Former Vendor
Joined: Mar 2006
Posts: 1,135
Likes: 0
From: Metro NY
In the circles I travel you will never get any performance data. The idea is not to give it out.
Former Vendor
Joined: Mar 2006
Posts: 1,135
Likes: 0
From: Metro NY
All you have to do is ask about Precision's track and race program and we'll tell you about it. We're actually very visible.
4th Gear
Joined: Oct 2003
Posts: 399
Likes: 0
From: Southern California
I hope this is not off topic...
Would someone comment on the material composition of improved valves and retainers, as well as the strength of the valve springs? I'm not asking for specific design details (e.g., angles), just general information.
I have a ported/polished head with the Schrick race cam on my MCS, but I am still running stock valves and springs. A friend who used to drag race 800 hp VW's suggested lighter valves (titanium) and lighter springs. The argument was for quicker valve closure, but I suspect this had something to do with revving the engine to 14k
. Is there any value for that path in a Mini with maximum revs about 7500?
As an add-on to "obe's" post, what suggestions do you have for maximizing the 3k-6k rev range? I fully realize that the whole system must be integrated and balanced, but what is the direction regarding valves and springs of most head developers?
Thanks,
Would someone comment on the material composition of improved valves and retainers, as well as the strength of the valve springs? I'm not asking for specific design details (e.g., angles), just general information.
I have a ported/polished head with the Schrick race cam on my MCS, but I am still running stock valves and springs. A friend who used to drag race 800 hp VW's suggested lighter valves (titanium) and lighter springs. The argument was for quicker valve closure, but I suspect this had something to do with revving the engine to 14k
. Is there any value for that path in a Mini with maximum revs about 7500?As an add-on to "obe's" post, what suggestions do you have for maximizing the 3k-6k rev range? I fully realize that the whole system must be integrated and balanced, but what is the direction regarding valves and springs of most head developers?
Thanks,
wait a while then ....damb!!!!! honey my head cracked !!!! oh look here's one cheaper than mini sells em for .!!
True but not true to the intent of my post.
That was that there isn't 1 perfect flow for every condition. It needs to be clear when anyone posts, be it vendor or others, is the how, when, where this increased flow does the most good. A head that flows 25% over stock and has a useful rpm range of 5-8K rpm is worthless to me yet very valuable to someone else. That is my interest in this thread.
I never took Bob's question as an inquiry into specifics but more along the lines of what works for the MINI.
The one consensus so far is the exhaust side sucks. A ton can be learned and taught without specifics. Don't care what valve angle(s) may have worked just that there is an improvement to be made over stock.
Without giving away a single detail any vendor can prove the effectiveness of their head/cam combo. They can also demoinstrate how it is most effective.
Ideally I want 3500 to 5500 rpms to be my fat zone. If I start wheezing over 6K I could care less. I autocross, pull out into busy urban traffic and onto freeways. If I don't have beef until 5K I might as well be walking or driving my minivan
Someone show me a combo that does that and I'll buy it.
This is why the M62 is so interesting to me. Get me 210lbs/ft @ the wheels @ ~5200
Edit:
Wrote this before I saw Randy's post. We've discussed this same thing before. It's all doable. What needs to be defined though is if venfors are doing a one size fits all for the price or building a more targeted solution.
That was that there isn't 1 perfect flow for every condition. It needs to be clear when anyone posts, be it vendor or others, is the how, when, where this increased flow does the most good. A head that flows 25% over stock and has a useful rpm range of 5-8K rpm is worthless to me yet very valuable to someone else. That is my interest in this thread.
I never took Bob's question as an inquiry into specifics but more along the lines of what works for the MINI.
The one consensus so far is the exhaust side sucks. A ton can be learned and taught without specifics. Don't care what valve angle(s) may have worked just that there is an improvement to be made over stock.
Without giving away a single detail any vendor can prove the effectiveness of their head/cam combo. They can also demoinstrate how it is most effective.
Ideally I want 3500 to 5500 rpms to be my fat zone. If I start wheezing over 6K I could care less. I autocross, pull out into busy urban traffic and onto freeways. If I don't have beef until 5K I might as well be walking or driving my minivan
Someone show me a combo that does that and I'll buy it.
This is why the M62 is so interesting to me. Get me 210lbs/ft @ the wheels @ ~5200
Edit:
Wrote this before I saw Randy's post. We've discussed this same thing before. It's all doable. What needs to be defined though is if venfors are doing a one size fits all for the price or building a more targeted solution.
6th Gear
Joined: Sep 2002
Posts: 2,196
Likes: 0
From: Hampton, VA
I hope this is not off topic...
Would someone comment on the material composition of improved valves and retainers, as well as the strength of the valve springs? I'm not asking for specific design details (e.g., angles), just general information.
I have a ported/polished head with the Schrick race cam on my MCS, but I am still running stock valves and springs. A friend who used to drag race 800 hp VW's suggested lighter valves (titanium) and lighter springs. The argument was for quicker valve closure, but I suspect this had something to do with revving the engine to 14k. Is there any value for that path in a Mini with maximum revs about 7500?
As an add-on to "obe's" post, what suggestions do you have for maximizing the 3k-6k rev range? I fully realize that the whole system must be integrated and balanced, but what is the direction regarding valves and springs of most head developers?
Thanks,
Would someone comment on the material composition of improved valves and retainers, as well as the strength of the valve springs? I'm not asking for specific design details (e.g., angles), just general information.
I have a ported/polished head with the Schrick race cam on my MCS, but I am still running stock valves and springs. A friend who used to drag race 800 hp VW's suggested lighter valves (titanium) and lighter springs. The argument was for quicker valve closure, but I suspect this had something to do with revving the engine to 14k
. Is there any value for that path in a Mini with maximum revs about 7500?As an add-on to "obe's" post, what suggestions do you have for maximizing the 3k-6k rev range? I fully realize that the whole system must be integrated and balanced, but what is the direction regarding valves and springs of most head developers?
Thanks,
What is relevent to your question though is price. Is it worth the cost and what is that cost? On a small block Chevy( granted this is years ago) you would be looking at doubling the cost, easily, over good components.
This gets cutting edge like dry lubing components. Worth it? Yes. Reeeeeally worth it? Break out the $$$$$
he's being profound it seems . very deep stuff . a philosophy major ? tree in the woods sh$t but no less true . i like many don't want to know all the physics just which sir do you recommend for my car ? it's a leap of faith ; hopefully we find a vendor with integrity .
4th Gear
Joined: Oct 2003
Posts: 399
Likes: 0
From: Southern California
. Sounds like titanium may in reality be "unobtanium" However, would it make sense to use titanium valves in the MINI drag cars? BTW, I've seen some aftermarket pistons and rods for the MINI --- very nice items, but they do cost a bit. I guess by the time one finishes the project, the only stock engine part might be the block itself .As one member of our club boasts, his "racing floor mats" make a big difference
.
Thread Starter
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6th Gear
Joined: Sep 2004
Posts: 5,149
Likes: 0
Driveability for a track car and for a street car are two different things..... I believe most head vendors offer a few different models...... I do agree that driveability is the key...... we get back to "have a goal"...... there are some head vendors that don't ask what you want it for they simply make a head..... if it is not optimized for their application it will turn out to be a less than optimum choice..... this thread needs to keep going for while.... we are getting some good info and questions......
Thread Starter
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6th Gear
Joined: Sep 2004
Posts: 5,149
Likes: 0
True but not true to the intent of my post.
That was that there isn't 1 perfect flow for every condition. It needs to be clear when anyone posts, be it vendor or others, is the how, when, where this increased flow does the most good. A head that flows 25% over stock and has a useful rpm range of 5-8K rpm is worthless to me yet very valuable to someone else. That is my interest in this thread.
I never took Bob's question as an inquiry into specifics but more along the lines of what works for the MINI.
The one consensus so far is the exhaust side sucks. A ton can be learned and taught without specifics. Don't care what valve angle(s) may have worked just that there is an improvement to be made over stock.
Without giving away a single detail any vendor can prove the effectiveness of their head/cam combo. They can also demoinstrate how it is most effective.
Ideally I want 3500 to 5500 rpms to be my fat zone. If I start wheezing over 6K I could care less. I autocross, pull out into busy urban traffic and onto freeways. If I don't have beef until 5K I might as well be walking or driving my minivan
Someone show me a combo that does that and I'll buy it.
This is why the M62 is so interesting to me. Get me 210lbs/ft @ the wheels @ ~5200
Edit:
Wrote this before I saw Randy's post. We've discussed this same thing before. It's all doable. What needs to be defined though is if venfors are doing a one size fits all for the price or building a more targeted solution.
That was that there isn't 1 perfect flow for every condition. It needs to be clear when anyone posts, be it vendor or others, is the how, when, where this increased flow does the most good. A head that flows 25% over stock and has a useful rpm range of 5-8K rpm is worthless to me yet very valuable to someone else. That is my interest in this thread.
I never took Bob's question as an inquiry into specifics but more along the lines of what works for the MINI.
The one consensus so far is the exhaust side sucks. A ton can be learned and taught without specifics. Don't care what valve angle(s) may have worked just that there is an improvement to be made over stock.
Without giving away a single detail any vendor can prove the effectiveness of their head/cam combo. They can also demoinstrate how it is most effective.
Ideally I want 3500 to 5500 rpms to be my fat zone. If I start wheezing over 6K I could care less. I autocross, pull out into busy urban traffic and onto freeways. If I don't have beef until 5K I might as well be walking or driving my minivan
Someone show me a combo that does that and I'll buy it.
This is why the M62 is so interesting to me. Get me 210lbs/ft @ the wheels @ ~5200
Edit:
Wrote this before I saw Randy's post. We've discussed this same thing before. It's all doable. What needs to be defined though is if venfors are doing a one size fits all for the price or building a more targeted solution.