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Fri May 26, 2006 5:29 am

Bad or good?

They have a reputation for being problematic here in the UK due to the large difference in size between the inlet and the outlet ports - (39 - 32 mm) causing overheating problems - is this true or yet another urban legend?

Conversely are they any better than standard size valve heads for flow etc.

Thanks

Fri May 26, 2006 6:18 am

I was waiting on this thread to show itself. :lol:

The 041 has the same valve ratio of Intake/Exhaust as Bus heads.

High performance heads in theory are supposed to have INTAKE valves 52% of bore size and EXHAUST valves 74-84% of INTAKE size.

If you follow this formula, you can see that the 041 is actually a pretty good set of heads.

Drag race heads follow the formula very well. Do the math and try it. It even leaves enough room for unshrouding the valves all the way around it.

To follow the formula on Type I heads, the exhaust guides need to be moved over some ===> remachining it over and grinding new guides.
However, this is for another thread.

cheers.

nick

Fri May 26, 2006 6:35 am

Thanks Nick - very interesting.

Fri May 26, 2006 7:38 am

nsracing wrote: ..The 041 has the same valve ratio of Intake/Exhaust as Bus heads.
Different type of engines! Too general.

Quote: ..High performance heads in theory are supposed to have INTAKE valves 52% of bore size and EXHAUST valves 74-84% of INTAKE size.....If you follow this formula, you can see that the 041 is actually a pretty good set of heads....
Theory, and then there is reality. The formula does not seem to work.

Fri May 26, 2006 7:52 am

PJMS wrote: nsracing wrote: ..The 041 has the same valve ratio of Intake/Exhaust as Bus heads.
Different type of engines! Too general.

Quote: ..High performance heads in theory are supposed to have INTAKE valves 52% of bore size and EXHAUST valves 74-84% of INTAKE size.....If you follow this formula, you can see that the 041 is actually a pretty good set of heads....
Theory, and then there is reality. The formula does not seem to work.

Don't think so. This IS REALITY. Take for example these CB Eliminators I did race prep on. 94mm bore. 48x40 valve size. Run the numbers and you tell me if it is only theory. :lol:

I am NOT going to pass on info if I cannot back it up.

check this out:

Enjoy.

Fri May 26, 2006 8:07 am

Still too general. You can be specific about your application but then to use that as general specs for just about any possible variation? If you use the formula on the 041 (in reverse) you will be running 75mm pistons which would make it a 1200cc engine! So, how does it work?

Fri May 26, 2006 8:32 am

Nick - just to confirm.

I'm fitting the 041's to a 1915.

The bore is 94mm, therefore in theory the heads need 48.88 mm inlets?

I can see the correlation between the inlet and exhaust size, but not the inlet valve size. Am I missing something?

Fri May 26, 2006 8:35 am

Some of are huge 300hp autocrafts 910 heads we build, have 50mm intakes, and 38mm exhaust valves.,96mm bore. The problem is getting the charge in, not getting it out.

Fri May 26, 2006 9:01 am

Gene Berg isn't so keen on 041 heads either. Heres what his website states:

"I do not sell bastard valve size heads that should not be used with the VW engine such as the 041. ... Any larger valve sizes should only be used when proper combinations provide a matched system from air cleaner to tail pipe. After all, you can't get it in if you can't get it out and if you can't get it out it provides less performance and runs hotter. Any restriction in the entire system will not provide good all around performance and will likely run hotter and make tuning extremely hard. That is why all automotive manufacturers provide a proper balance from intake to exhaust valve sizes with the only exception being smog controlled heads."

Fri May 26, 2006 10:27 am

UK_Monkey wrote: Nick - just to confirm.

I'm fitting the 041's to a 1915.

The bore is 94mm, therefore in theory the heads need 48.88 mm inlets?

I can see the correlation between the inlet and exhaust size, but not the inlet valve size. Am I missing something?

Geeze H. Man. What did I start now? :lol:

If all we care about is to follow the theory, then sure. That is what it calls for.

But...it is all machining challenge.

#1 the axis centers between the valve guides is very limited in the Type I configuration. They are too close. If you look closely the exhaust has a LOT of room to move closer to the cylinder wall. By moving the exhaust away from the intake will create more room for both valve sizes.

These are the maximum you can do to the valve sizes and limited by the BORE size.

#2 Darren's question with the 96mm bore and 50mm intakes is right where it should be. Sticking a 84% of intake EXHAUST size is 41.9mm. This will fit if you move the exhaust guide over some.

#3..I did not develop this formula. NASCAR did. Playing in the machine shop with these stuff is a lot of work. As I indicated above already, even the "unshrouding" is factored in with the formula.

#4..Gene did not agree to a LOT of things which is fine. It is allowed. The end-user will have to decide what info to follow.

I am NOT preaching here. I am only sharing the info. :wink:

Fri May 26, 2006 10:31 am

Darren Gurrola wrote: Some of are huge 300hp autocrafts 910 heads we build, have 50mm intakes, and 38mm exhaust valves.,96mm bore. The problem is getting the charge in, not getting it out.

Well Darren... I do not want to preach to the choire. But you have to choose the CORRECT CAM for that. Right lift, overlap, and duration.

We can talk about valve sizes and angles, port runners size, flow reversion theories all day long and accomplish nothing. The cam still dictates a lot of it. But you already know that I am sure.

Fri May 26, 2006 10:54 am

Generally speaking 041 heads ,39 intake 32 exhaust , on a vw engine will make a little more power in the mid range -no more power in the upper range and make it tough to tune in the low range[and make the engine run hot] . There are much better choices for your engine .Put a 35.5 exhaust on those heads and your engine will like it a whole lot better. I don't know , maybe Nick can make you a special cam to make them work better :roll: .

Fri May 26, 2006 11:19 am

Lets keep it clean eh kids? :o

Fri May 26, 2006 12:38 pm

Oh..sure. It is called Engle 110. :P

Like this one...

Fri May 26, 2006 12:52 pm

Im running 041s on my woods buggy 2165. They seem to produce plenty of Horsepower. I read all of the posts on them and was a little apprehensive however I gambled with them. I also ported them. Im no expert however they seem to flow fine. No I did not put them on a flow bench to get them equal. I figured worse case senarial I could allways buy some Simms or CBP ported heads to put on the motor. So far Im happy with what I have.

Fri May 26, 2006 2:09 pm

NSRacing do you have a Website? What are your prices? Heads, Case, rebuilt motors? Ported heads? What, it is such a secret on what you do?

Fri May 26, 2006 4:16 pm

NS, I have some very very high end software, used by the big boys that build v8 prostock engines and heads, and a ton of formulas compiled. All the cams are custom for the big vw heads/engines, lift well into the .750 range. The flow bench and dyno are great tools, but the race track tells the whole story.
Also being connected with some of the best engine builders in the world helps alot too. I have some very close friends, that are connected to the industry,all in all, we all know the same stuff:)

Lot of ways to skin the cat for sure!

Fri May 26, 2006 4:27 pm

Fri May 26, 2006 5:03 pm

Darren Gurrola wrote: NS, I have some very very high end software, used by the big boys that build v8 prostock engines and heads, and a ton of formulas compiled. All the cams are cutom for the big vw heads/engines, lift well into the .750 range. The flow bench and dyno are great tools, but the race track tells the whole story.
Also being connected with some of the best engine builders in the world helps alot too. I have some very close friends, that are connected to the industry,all in all, we all know the same stuff:)

Lot of ways to skin the cat for sure!

Yea..I know. Very impressive. I can only wish. :P

I got to take a look at one set of 910 heads reworked for the roller rockers and moved pushrod holes for 3/4" lifts that came from out west last year before the assembly. I was there to observe and take in info....not to disapprove. I was also at the track for the testing/racing. It did not do very well.

My only point was that...if the flow stopped at around 0.500" lift, why bother lifting the valves beyond that to 0.750"? I was just making sense of it. I am just a nobody...can't step on anyone's toes. :wink:

Fri May 26, 2006 6:01 pm

If the heads are correctly designed, the more you lift the more they will flow.
Good luck.