Flownumbers, 3400 Vs 3500

[Vegeta]

Ported heads for comparisons will be next. For now, you can get an idea for how things are gonna work with stock heads. I will get much more in depth and technical about this once I have the ported head flow number comparisons with and without manifolds.

3400 lower intake doesn't work on 3500 heads and vise versa. Flow is not the end all be all to the quality of the heads/manifolds. From a design standpoint, the 3500 parts are better engineered than the 3400 parts.

[Sprucegagt]

Good work Ben! I look forward to seeing more info on the comparison.

[Vegeta]

Before I continue, I want to make something clear. I use a cylinder bore in my flowbench that is less than .020 over for a 3400 engine. This shrouds the valves just like the engine does, so I can simulate the flow numbers. I use a clay molded bell shaped opening on the bare heads, and a tube on the exhaust ports (not flowed for this discussion). Others may not share their test setup information so it is impossible to determine how their numbers are obtained.



Quote:
Originally Posted by MilzyZ34
I don't see the lower intake as being a restriction. So it would probably flow the same amount.


(question from dyno thread about MMMs car) This was in regards to his 297 cfm @ .600 or so lift from his stage 3 3400 heads. Obviously if you have looked at the .pdf file, you will see that the ported 3400 manifolds still restrict flow ~ 14% at 214 head cfm (185 with the manifolds on). If the % loss was static, that is 255 cfm at the head. However the % loss changes based on the head alone numbers going up since the manifold will become more and more of a restriction.

Why do I bring this up. The stage 3 kit is being marketed as an NA setup. NA motors rely on vacuum to draw the air and fuel into the chamber. By opening up the heads to such a degree, you have less velocity at lower RPM as well as the lower lift. You will require the engine to rev more before you get your velocity back, but even then you still have the manifolds restricting your flow.

For boost, this is not an issue because the intake is pressurized. You can have huge cc intake runners because your velocity is already a given from the turbo or supercharger.


Quote:
Originally Posted by MilzyZ34
Correct, much much more power over a set of stock 3500 heads


Those are his words comparing the stage 3 MMS heads to stock 3500 heads. What about the application? What about the rest of the system? The 3400 manifolds won't support the numbers like a 3500 manifold set will. This is why I have been working hard on 3500 heads and manifolds. Even better are the non flow related reasons the 3500 setup is superior to the 3400. The 3500 heads themselves have a new design in th intake port, with the port starting higher and coming down at the valve at a more direct angle. There is a fin in the bowl area behind the valve to help direct the air/fuel mixture around the valve and to help keep the fuel in suspension. The short side radius has been changed, and there is a "funnel" as well to directly swirl the air past the valve. The exhaust side has a sloped roof to promote flow around the valve. GM did a lot with the gen 4 design on the 60V6 and to ignore these great steps forward by only discussing flow numbers is sad and misleading. Flow is not everything. You have to build a complete system, not just create hype through huge numbers that won't be supported by the rest of the system, aka, the intake manifolds.

If you want more information on velocity and flow, let me know.

[Sprucegagt]

Very interesting questions and with solid information to back them up. Sadly I'm afraid the information here will go completely over most people's heads.

[lone_wolf025]

Uneducated question: There is no chiseled in stone standard for porting and polishing heads correct? If that's the case then theorectically one set of ported heads can flow better than another that are the same part?

And as spruce said the information is a little over my head but how accurate are flow numbers in showing how much power can be gained from something? One other question obviously in terms of raw flow the bigger is better, but has anyone done a 3500 ported swap and compared it to a ported 3400 and seen the actual resulting power on an engine?

For the record I'm not trying to start an arguement I'm just asking questions to understand what's better in terms of power that is produced on an engine.

[Sprucegagt]

1. Uneducated question: There is no chiseled in stone standard for porting and polishing heads correct?

2. If that's the case then theorectically one set of ported heads can flow better than another that are the same part?

3. And as spruce said the information is a little over my head but how accurate are flow numbers in showing how much power can be gained from something?

4. One other question obviously in terms of raw flow the bigger is better, but has anyone done a 3500 ported swap and compared it to a ported 3400 and seen the actual resulting power on an engine?

For the record I'm not trying to start an arguement I'm just asking questions to understand what's better in terms of power that is produced on an engine.

1. You are correct. But each supplier has there own methods and designs for porting.

2. Correct again.

3. I'll let Ben answer this one.

4. This is where your wrong. Bigger is not always better. As Ben was pointing out. In a N/A setup you want velocity as well as flow. In sacrificing one for the other you make an engine that is usually a dog. Now in boosted applications you want all the flow you can get. Your turbo/supercharger will provide all of the velocity. As for comparing a ported 3400 vs. 3500, I don't think anyone has done that yet.

[Vegeta]

There is a lot of theory when it comes to head porting and design. When I started porting heads, I didn't know about this theory. This was my 3.1 gen 2 motor, and I didn't do it any favors. Recently, a guy sent me a set of heads that he bought from a race shop off ebay that looked worse than my first attempt. It was claimed to be flowbenched as well but I flowed it at a significant loss in flow compared to stock heads of the same casting. Had myself or these guys known the theory, things wouldn't have been so bad.

Beyond theory comes flow testing. This lets you quantify the air at a given depression, which is 28" of water standard these days. 10" is the old standard. Basically as you increase flow through the valve you have to increase the pressure as well. A running engine doesn't work like this at all but that is where I take my numbers and use simulation software. Its not "real world" but its good for getting a starting point for real world. A running engine will have pulses in the intake and exhaust ports, high and low pressure areas that will help/hurt certain "tuned" RPM ranges. Thats a whole other topic:P

The pistons moving down give you the depression in your engine, which varies with piston speed. The valve opening events play a huge role in performance because it determines when the valve is open at x lift in relation to the piston speed and when you want it to be hitting peak depression vs flow through the valve. Granted that all changes based on RPM and those pulses/high and low pressure areas.

To compare .500 lift numbers on a .556/.559 lift cam is marketing. The majority of useful lift/depression is spent at the mid lift range. With heads that flow so much better down low, you can go with a cam that delays the intake opening and closes it later. This helps with the higher RPM power plus you still get a smoother idle than going for all high lift flow while hurting your low/mid lift. FYI, the .050-.150 numbers important, but milzymotorsports doesn't have those flow numbers. I don't understand why you wouldn't want those numbers when you are researching your port work.

I think thats enough to cover #1:P

I have a 3500 test head that you might find interesting. Both have the same average flow from .050-.500, but one is my "level 1" porting and gives 9-15% more flow at .050-.200. It goes down to just above stock at .500. The other is the start of my "level 2" that will be for boost. It has less gain at low lift, though still pretty decent, but really starts to flow a lot more than stock at .350, gaining 10 CFM at at time to be 240 cfm vs the 218 stock at .500. 2 completely different portings for different applications but overall, they could be considered equal if all I told you was that my port work gains 9% flow average from .050 to .500 lift on both heads.

#3. Flow numbers are an idea of what you can potentially get. However, flow numbers alone are worthless because you don't know how big all the ports are and valves. You also have swirl and tumble, which you can read both sides to it being good to have or not good to have. If you look at aftermarket heads for 350s and such, you will get CFM and CC measurements. For a street rod, you want high flow with smallest cc for the velocity. For a blown muscle car, you want bad ass flow and 2 pitchers of beer in volume on the runners. Putting those bad ass heads on your street rod will make it not run. Thats an extreme, but you get the idea.

#4 Milzy has the 3400 numbers (and records if you think the internet has every 3400 dyno sheet on record...hahaha). I think someone with his stage 2 setup should swap a set of ported 3500 manifolds with stock heads and dyno it. I have the FPR brackets now to fix that issue:) Oh, and 1 stipulation. Both get a 65mm TB for the dyno so we aren't comparing TB sizes and claiming it to be something its not.

[bszopi]

Check out www.theoldone.com for more information on head porting, and a lot more.

More specifically the archive area, www.theoldone.com/archive/.

[Metallman56]

very interesting

[lone_wolf025]

Thanks for the replies guys.

[Ajaxus]

alright, im gonna be an uber n00b and ask if there's a website i can go to that will teach me how to read those numbers on there and what they mean? :( i wanna learn

[Vegeta]

http://www.highperformancepontiac.com/tech/0210hpp_cylinder_head_flow_testing/

"When discussing flow numbers for a potential porting job or the purchase of a set of heads, always identify the bore size used along with the test pressure, or you may not get what you paid for."

[Vegeta]

http://www.tonydrews.com/Flowbench/FlowBench.htm

Good read, the best being the notes at the bottom.

"Porting heads is a lesson in humility. Air in a port does not go where it is supposed to go according to common sense. In some areas sharp corners are better than round ones. Some combustion chamber mods that you “know” will improve flow simply do not.

Increasing size of a port will increase flow, up to a point, but it may actually kill horsepower because of the decrease in velocity.

A person needs to read as much as possible on the subject, but even then you will find that the written material is not such that you can apply it directly to our dumb old ports. Virtually all head porters do not divulge how they get their result, because we all feel that we should be compensated for those hundreds of hours we’ve spent experimenting.

You do learn some interesting things, though. Examples:

When you install a hard seat, it seldom matches the bore exactly under the valve. It looks like it should be blended, rounded, filled in, or something to make it match. Actually, this makes a surprisingly small difference.

Straightening out the curve in an intake port, something that we just “know” will help, actually decreases flow.

I have done engines where the former porter made the ports really large. Big flow numbers on the flow bench. Then to match the manifold, they put a big chamfer on the outlet side of the manifold to match it to the head. The end result, when the head and manifold were measured as an assembly, was that the whole system flowed less than a stock system!

Finally, I shudder when I read that someone is “matching” the ports. Unless done properly, this can decrease flow and horsepower. At the head face, if you match by enlarging the manifold a short difference, flow suffers. For intake ports, the square are of the port should either be constant or it shold converge slightly. Any divergence or increase in area will harm flow and velocity. On the exhaust side, it is actually good to have the port slightly smaller than the header pipe and leave that shoulder, because it helps reduce reversion, that cloud of raw gas you see standing outside the SU carb inlet on a cold and damp morning. "

[Vegeta]

Crane Gold Race Rockers can fit the 3500 heads with some modification to the top of the heads. The pushrod guides won't fit unless you grind down on the head. The advantage of the crane gold race rockers are reduced friction, stronger (i have seen and heard of a couple stock rockers breaking at the fulcrum and at the pushrod seat), and closer tolerance to 1.6:1 than stock.

I know this was an issue for some people I talked to so now that has been resolved. It didn't affect my porting either, which was my boost oriented prototype design.

[AaronGTR]

Two questions. Where the rockers you heard of breaking 3500 rockers or 3400 rockers? I've never heard of 3400 rockers breaking but they do look beefier than the 3500 rockers. Also did you drill and tap the heads to accept the rocker studs or did you find some different rocker studs? I ask because as you know the crane rockers come with 10mm to 3/8" conversion studs and the late model 3400 and all 3500 heads switched to 8mm bolts for the stock pedastal rockers.

[Vegeta]

Here are some pictures of the rocker arm I pulled out of a 3400 engine I bought. Friend of mine had the same thing happen to his high compression/cammed 3400.

I found some ARP studs that work out great:) I was going to go with the drilled/tapped heads but thats a pain in the ass and this works out better. They are in the pictures above.

Ill have my prototype ported 3500 heads with stock and ported manifold flow comparisons up as soon as I find the bolt for my valve opening device. 8mm thread pitch owned me again.

[Vegeta]

Ok, so im a liar. I can't post the numbers because its too valuable to my business. All I needed to show was that 240 cfm flowed 199 cfm through the ported manifold. Thats a 17% loss from the ported intake manifolds.

Ill post more when I can, or if anyone wants to discuss anything about the flow numbers or the 3500 parts.

[harvester45]

I haven't looked at your site in a while, but do you have a 3500 top end ported for boost? Do you have any results from testing with these? Also, what is your opinion on lowering the CR for boosted applications? I know Milzy talked about keeping the compression ratio the same, but I'm really liking the 3500 setup, since I could lower my CR a little without new pistons. When it comes to stuff like this, I'm kind of ignorant, so forgive me if any of these questions are dumb. BTW, If you're looking for a test car to sponsor this spring/summer, I may be able to voulenteer mine. ;)

[Vegeta]

Well, I haven't had any testing done on a dyno or anything as I am still working on my port work. I thought I had something done but after flowing with the manifolds, I have to start over:( Not really starting over so much as tweaking what I have figured out so far cause I think I can do even better.

It depends on your setup really. If you can flow a lot of air, I wouldn't worry about dropping compression down some. If you don't have a big sc or turbo, then I would raise the compression. The design of the 3500 heads is really nice though so unless you have some nicely ported 3400 heads, this is really a simple answer:) Swap to the 3500 top end.

Im not sure about any sponsor deals right now. Everyone wants a hook up, and I understand that. For now I will focus on hooking you guys up with good information. Perhaps in the spring/summer things will look better for sponsoring someone.

[jackal2000]

Friend of mine had the same thing happen to his high compression/cammed 3400.

now you got me worried that this will happen to me....i hope not.

[Vegeta]

I dont think its related to the compression or the cam honestly. I think there are jst some weak stock rockers out there. I have been looking for a long time now, for a steel narrow body SBC rocker arm. I really don't care about competition so much on them as it would just be better if someone had one available for us. Most of the rockers that are the right size are too wide:(

[jackal2000]

thats some what a relief of my worries. stay strong rockers!!

[harvester45]

Well, I haven't had any testing done on a dyno or anything as I am still working on my port work. I thought I had something done but after flowing with the manifolds, I have to start over:( Not really starting over so much as tweaking what I have figured out so far cause I think I can do even better.

It depends on your setup really. If you can flow a lot of air, I wouldn't worry about dropping compression down some. If you don't have a big sc or turbo, then I would raise the compression. The design of the 3500 heads is really nice though so unless you have some nicely ported 3400 heads, this is really a simple answer:) Swap to the 3500 top end.

Im not sure about any sponsor deals right now. Everyone wants a hook up, and I understand that. For now I will focus on hooking you guys up with good information. Perhaps in the spring/summer things will look better for sponsoring someone.

Ha ha! No problem, I just thought that I'd throw my name out there in case you were looking for a turbo'ed car to test the 3500 top end out on. If you do get to that stage, shoot me a PM or e-mail, because I'm definitely interested.

I'll take you up on your offer of info, though. Do you know at what PSI and/or HP lower compression is advisable on a turbo'ed 3400? How much air is "a lot"?

I plan to wait till parts break, then bore it out and get forged pistons. But if I got pistons and pulled the engine, I'd want to do everything at once. Like lower compression pistons (if that is the right way to go), a boost-specific cam, UD pulley and anything else I'm forgetting. So knowing what CR is best for my set-up will be pretty important when I'm looking at these parts.

I'd PM you this, but I really like all the new info that's been coming up lately, and maybe this will help somebody else other than me.

Basically, I guess I should just read on 60degree more often, but I'm too lazy. lol

[Vegeta]

I have no experience with boost so I don't know what amount of flow would be best for a given compression and cam specs. In fact, its a very dynamic question because there are so many factors. Its safer to lower your compression and up the boost, and yields better results from those that have answered on this topic before. Only for those with advance knowledge on the subject should try to go high compression with high flow/boost levels. Check theoldone.com for info on a high compression high boost civic. Crazy stuff.

If I had to give out my best guess, I would run a forged piston to the same specs as the stock piston with slightly more dish in the piston, and modify the heads a little so you can still keep your compression damn near 9:1 and still shave the heads some.

Kinda off topic in a way but I am working with the machine shop here on some racing briggs motors and my dynomation software. Im learning quite a bit more about the software itself while doing this 1 cylinder engine and will definetly be utilizing its abilities. This will be useful for plugging in flow numbers, turbo specs, and compression/cam. It won't tell me what is safe or when you will have knock issue. It only factors that you can tune it properly any way it needs to be done.

Kinda more off topic, I need more literature on flowing the manifolds on the heads.

http://mototuneusa.com/

"Smaller Intake Ports Gain 7 % More Power "

Check out the high velocity intake porting.

[bszopi]

Check theoldone.com for info on a high compression high boost civic. Crazy stuff.

Larry Widmer's 1.5L, 11.2:1 CR, up to 27psi boost, 487hp, "errand running" Civic... Oh yeah, it runs on pump gas and gets 25mpg in the city as well.

http://60degreev6.com/backup/hlperf/SC_Honda.jpg

They are actually in the process of redoing the engine, so who knows what it'll be capable of.

[Vegeta]

I was hoping someone would read that mototune site.

Here are some pics I took of the pushrod gaskets.

First pic is the 3500 plenum gasket on the 3500 manifold that has black marker where the 3400 gasket would port out to. You can see how much bigger the plenum to lower intake can go with the metal gaskets

Second pic is of the gen 2 FWD, gen 3 small port, gen 3 large port, and gen 4 plenum gaskets. Last pic is the gen 3 and 4s stacked on top of each other.

I need the 3900 plenum gasket.

[harvester45]

Good info! Thanks for the replies, I'm trying to get all the links read.

[zerocool]

very interesting and imformative. if i was still in MI i would have a new winter project;crap ...

id hafta dig out my physics book, but i know that ive seen the math behind the theories before. great articles!!!:applause:

[Vegeta]

http://www.importtuner.com/tech/0509it_cylinder_heads/