Intake manifold volume and design

[Polish]

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For something constructive, why not just cut off the stock plenum and design your own and weld it to the stock runner setup. If done right you would probably get close to what you are looking for anyways and save the trouble of the runner situation which is the hardest part of the whole design/fabrication.



Thats actually not a bad idea, some old skoolers did it years ago. Not sure of the results but it's worth a shot. You could port the runner inlets to bell shapes while the plenum is off also. Not to mention cost would be WAY less.

 

I have a lincoln tig 225 with a 3/32 zirconiated tungsten. I am using pure argon why would I use an argon/oxy mix? Argon is to sheild the weld pool from oxygen and other contaminents, sheilding with oxygen? Never heard of it for GTAW process. I was just planning on having the finished manifold flanges flattened by a head shop. I dont have a break or a shier. Is that how shear is spelt? Who said I wasnt using velocity stacks? where are you getting all this info from? I might just make my own v stacks or get them from ross machine ross is about 50$ a piece. In all honety I am thinking of a completely different design one that is more symmetrical being fed from I/C piping that is routed over the valve cover. When I mock up a cardboard proto I will post up pics for more opinions.

 

You have given us no real idea how you want this setup. By your statement of the IC pipe being routed over the valvecover I would assume you mean the middle of it going from the front of the car to the rear which changes the whole manifold design and some of the info given is not on topic cause everyone was assuming a typical SMIM that would come in one side and run across. If you are going to have the TB placed in the "middle" and split out changes the whole design.

Am I on the right track with my assumptions? By you giving a vague idea of what you are looking for the talk about the plenum designs are wrong and change. Also I think if you run your IC pipe the way it seems you are talking about you will have to cut your hood

Why not do a little CAD drawing so we can see exactly what you are looking to make. What series aluminum are you planning on using?

BTW the ross VS are too small for 4g63 application.

 

[slugsgomoo]

i'd like to see how much more or less you end up spending than buying a smim, also how it looks, what kind of pressure you can test it to, and then do a comparison on a dyno between the two.

Honestly, flanges aren't that expensive to just buy (i think Shearer will even sell 'em to you) and a drill press and porting tools are never going to have the quality that a nice cnc/waterjet cut piece will.

Honestly, there are other projects you DIY on the car with a better cost/benefit ratio than this one.

 

You're so immature and uncouthness slugs.

 

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i'd like to see how much more or less you end up spending than buying a smim, also how it looks, what kind of pressure you can test it to, and then do a comparison on a dyno between the two.

Honestly, flanges aren't that expensive to just buy (i think Shearer will even sell 'em to you) and a drill press and porting tools are never going to have the quality that a nice cnc/waterjet cut piece will.

Honestly, there are other projects you DIY on the car with a better cost/benefit ratio than this one.

I wouldn't buy a bolt from Shearer, I bought a T3 flange from him and he told me a price and when the flange showed up there was a little note on the inside saying that his supplier raised there price so he had to do the same. The only problem was the price was doubled. Yes I paid 70.00 for a T3 flange from Shearer and he didn't even bother asking me if I still wanted it, he just charged my debit card without asking(NO LUBE). He has done the same thing to several other people that I know for much more. I won't mention any names but someone I know just had a manifold and intercooler custom made and the bill was spose to be 7-8000.00 but in the end it was 12,000. If something is going to be 4-5000.00 more wouldn't you call the customer and ask if you want me to keep going or to stop??? Im done with Shearer!! Im sure some crybaby on here will go and tell Shearer what I am saying but I really don't care, I have hard facts to back up what I am saying and its to small of a community to be doing crap like this.

 

[Rausch]

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I suppose I am looking for an easy way to design it. Does anyone have an aftermarket intake manifold that they could give the approximate dimensions of so I can figure out some proven plenum volumes and runner lengths?



You mean you are looking for a way to do no work with no knowledge and find a manifold that someone has already done all the work, research, design and testing on and copy it for yourself. Not sure the reason behind this would be since it would cost less just to buy a version of the manifold you would be copying.



This, and all your posts after it are really just taking up space. the guy is asking some BASIC questions pertaining to an idea that he has. THATS IT! those that chimed in have provided plenty of USEFUL information. all i have read from you is questions and slightly derrogatory comments, no useful info, nothing. This is a TECH section not a BS section. Every question you asked has NOTHING to do with the topic of discussion. WTF?

 

Actually they do. If he would tell me what material he was planning on using I could make suggestions on something better or not. Same reason behind asking the questions I did about what he will be welding with, what tung and filler, etc. Which I'm sure you don't know jack about which is why you don't think any of it is on topic. Also about the fact that the ross VS will be too small for his application and having to cut up his hood for the way he was discussing about running the IC piping. Theirs plenty of other posts from other people agreeing with some of my posts, feel free to go bug one of them that might actually care about your post which happens to be the only real, truly off topic and useless post in this thread.

 

Ok can we please get back to the basics? I have absolutely no experience with cad or anything to show you waht I am thinking. But yes what you described Digit is about what I am thinking. The I/C pipe will not completely go perpindicular to the valve cover but close. I have already checked and a 3" pipe sits on my valve cover with the hood shut no problem. I am not sure what series aluminum I will be using maybe 6061 or a possible 5*** series If you have a reccomendation that would be great! Are you sure the Ross rectangular velocity stacks are too small? Do you have any suggestions as to where I could get the right ones? Does anyone have any usefull opinions on a moderately symmetrical top fed SMIM? How will the design criteria change Is it worth a try?

 

[Rausch]

^ take a look at the designs for boxer engines. at least as far as the TB location goes. only thing i can think of that may be a hinderance (depending to a large degree on design) would be airflow to the 2-3 clyinders vs. 1 and 4. you may end up with more flow to the 2-3 cylnders than the others, but under boost, it may not be as much of an issue....

i'm thinking if you chopped the inlet side off of a boxer designed mani, and essentially mated it to our stock mani from the top, that would give you a ballpark to start from. at least a visual point of reference...

 

I have actually doing a manifold design like this before. 6061 will work or any 50 series, I like 50 series myself personally. If you want I can have the flanges waterjet cut for you. What TB are you planning on using? The ross will not work they are too small, remember how huge the inlets are for 4g63s they are the same as sbc pretty much. If you plan on doing the runners as a tube you can get some VS's from Magnus I think. Depending on the plenum design would be how the runners are done. Either straight out or curved like the oem manifold. If I was you for a test run I would definitely try the setup using the stock runners and cut the plenum off and setup your own plenum. I think it would save a lot of trouble, hassle time and money. You could also try designing something like a GT40 style intake manifold.

 

[Boostin21]

OK since we are on the topic. I have a set of hayabusa ITB's that i would like to use within the next 2-3 years on my vr4. they are either 60mm each or 63mm each i dont remember. Now first i have to say i am NO fabricator nor Math wizard so i dont know numbers. Now i am going to school for welding and i am currently working with TIG. Next year i will going to another school for Welding/Metal Fab.
Anywho, based on the small amount of fabbing knowledge i have hear i go. With using the aliminum ITB's i was hoping to use alum. v-bands off the ITBs themselves, and go to an ALL stainless steel plenum and through the ITBs to SS runners. I like the SS thought for the fact that SS is more heat resistant than aluminum. Now how is the distance or how should the distance be measured from the throttle plates to the cylinder head, to the center of the combustion chamber? or front of the intake valves? face of the cylinder head?
now i would like to go with about 2.25" runners to the head. Would i see gains or losses if i designed it like a tubular exhaust manifold?

 

i still have my JMF manifold you can borrow to get some ideas as long as you dont mess it up

 

WOW. lots of funny info here.

curtis quotes
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Runner cross section areas should be the same from the ve stack to the head.


the runners should be tapered. they need to be larger cross section at the VS and smaller at the head. dsms are goddam huge at the head. a 4g63 intake gasket basically fits the intake ports on my 800+hp n/a big block chevy.

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Most turbo intake builders design the plenum to be 70% of the volume of the engine.


most serious effort forced induction engines want about 1.5x displacement. sometimes more. tapering the plenum can help you get away with a smaller plenmum. the larger plenum helps act as a buffer to even out flow between runners if you tb is on one end of the plenum, like pretty much all dsm intakes are.

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It is usually better to have a square runner from the head to the plenum and have a ve stack that is square with radiused corners. Air doesn't like to change shape at at the speed of sound and causes internal friction.


yes try to keep the runners the same shape. but also try to keep nice large radii in the corners. no sharp corners!
also intake air doesnt travel at the speed of sound. exhaust does.
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boostinhard
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The hardest part to get correct is the pulse tuning that Dial caliper is talking about. It is very easy to blow up an engine if your pusles are happening at the wrong time and there is to much air going into one cylinder and allot less air going to the next.


this is something im not quite as versed in but everything ive seen pretty much does away with any kind of heimholtz tuning in a forced induction application. truth be told, most people dont even bother with it too much in n/a apps. look up some of the old dodge super stock intakes. they tried to take advantage of those theories and all they ended up with was 8 foot long runners. the whole blowing the motor up thing is way out in left field though. ive never heard of that. ive heard of problems with distribution because of plenum design but not because of runner length pulse tuning problems.

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Just buy one thats been proven and you will be better off. But if still decide to build one I wish you the best of luck, and I will give you as much advice as I can.


+1
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digit
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For something constructive, why not just cut off the stock plenum and design your own and weld it to the stock runner setup. If done right you would probably get close to what you are looking for anyways and save the trouble of the runner situation which is the hardest part of the whole design/fabrication.


you just love this idea. its a potentially OK idea. as long as you port the intake to be what you need. in order to port it you will need to cut the runners off before the 180* bend, which should be done anyway. but then the path that the runners take right before the head kinda messes with things. it could work, but it would be a last resort for me personally.

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BTW the ross VS are too small for 4g63 application.


ross mostly does stuff for the honda and nissan crowd. as i said earlier in the post, dsm ports are HUGE. the ross stacks are very nice but they are just plain too small. same with all their runner tubing.

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remember how huge the inlets are for 4g63s they are the same as sbc pretty much.


if youre going to 'borrow' my info as your own at least get it right. a dsm intake port dwarfs a sbc intake port. same with the exhaust port. my heavily ported aftermarket big block heads are about the same cross sectional area both intake and exhaust as a stock dsm head.
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boostin21
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I have a set of hayabusa ITB's that i would like to use within the next 2-3 years on my vr4. they are either 60mm each or 63mm each i dont remember. Now first i have to say i am NO fabricator nor Math wizard so i dont know numbers.


63mm is 2.5 inches. area of a circle is pi*R*R so with R being 1.25, pi*1.25^2 = 4.9. i dont remember the measurements off the top of my head for a dsm intake port but its probably fairly close. i would guess they are in the range of 1.8-2" tall and about 2.5 wide. that puts the cross sectional area at about 5" so your stacks are right at the size of the opening of the port. problem here is runner taper. if you cant get anything bigger they will probably work, but they wont be optimal because you wont be able to put much, if any, taper into the runners.

 

Obviously, you have never been involed in making an intake manifold and have never tuned an engine with a wideband in each exhaust runner to see the effect and seen what pulse tuning is. So you sir, are out in left field. Good day!!!

 

Ever seen anyone spray a single shot of N20 and blow up #1 cylinder. This happens on a poorly designed intake manifold and has allot to do with pulse tuning. But, what do I know?

 

what makes you think its the pulse tuning?

 

[JNR]

To the OP...Whatever you do in fabricating a manifold, it would be nice to see something a little different than all these copy of copies of SMIM's that are on the market...I myself would like to see a true dual runner design and/or a drastic improvement over the stock unit (which, other than the higher rpm's, these SMIM's don't do that)...

I have some sketches of a fresh dual plane unit that I would like to build someday (no, I cannot share them just yet /ubbthreads/images//graemlins/smile.gif ) and if all works out well, who knows where it'll go...worst case, it'll be a fun experiment.

I've asked this question before, but why aren't any manifolds made out of stainless steel? Is it the weight issue (although with proper geometrics, you can use thin gauge), heat retention, cost or ???

Too bad you weren't using a 2G head, as I have about 3-4 CNC cut flanges that I should probably get rid of someday.

One thing's for sure, be happy with EFI, we only have to deal with air on the intake, unlike a carb setup.

 

The N20 not being divided and sucked into each cylinder and being dispersed like a well designed manifold will do.

 

so its not the plenum size/design and runner entry location/design that does it?