home made sheet metal intake

[DanGST]

Im really interested to see how they work

 

[tkelly27]

I'm not an expert. I have had a fluid dynamics class, and done a little CFD. I'm not trying to tell anyone how to build a manifold, but talking about them is fun!

I had read a paper that did CFD analysis to bell mouth shapes, specifically for racing manifolds. It found that they are most effective when they are round, and off the floor of the manifold. If I remember right, a gradual taper from a round bell shape to the oval shape of the ports has less of an effect on flow than the turbulence a square intake tube causes. If you think about it, all the the air is going the same direction 360 degrees around a round one, and in a square inlet the air has to fight in the corners. A square bell mouth on the floor is better than a pipe (square or round) stuck to a flat surface or sticking above the floor of the manifold. I'll try and dig it up, but it might be difficult to find again.

http://2.bp.blogspot.com/_ok92T4mBPv0/TDizsJc73rI/AAAAAAAAAT4/zjWSqU3k9LE/s1600/03.jpg

I got to see one of those in person at a Ford dealership (it is in Sandy Oregon and they don't care if you touch it, for those who want to play with one). It has intake ports similar in size and shape to the small port 2G DSM head. Big open round bell mouths. You can see it in just about every F1 engine video too

The Best Ferrari F1 V12 Engine Sound - YouTube

those are limited to 4v/cylinder, so unless they have figured out a way to make two circular valves next to each other a circle, those ports are oval under those round bell mouths.

Being off the floor and not part of the floor helped to draw air from an area greather than the 180 degrees that the floor limits flow to.

I always wondered if there were benefits to a tapered plenum. I had thought the air in the plenum is supposed to be so large in comparison to what the engine ingests that it should be moving verly slowly. I was under the impression that there were pulses that pull the air out of it, so it is not steady state flow like in an intercooler

BMW Turbo F1 Engine

I've never seen a tapered manifold on a F1 engine, even ones configured similar to a 4g63. I'm not saying it is wrong, I'm just confused by it.

For what it is worth, a local shop told me they tested every aftermarket IM available on the dyno, and then a few of their own. They found that the most horsepower was made with a 1G IM flange with about 3" of runners, an aluminum fire extinguisher, and a Q45 throttle body. The fire extinguisher was still red!

Your welds are awesome! Excelent fabrication on the manifolds. Will look foreward to when you can have them tested. They look like they can make power : )

 

[sparky1987]

Tofastforu can't wait to get this one done im really excited about this one can't wait to see how this one done. Id really like to get some numbers on the first manifold I sent you guys.

 

[tkelly27]

I FOUND IT!

http://www.profblairandassociates.com/pdfs/RET_Bellmouth_Sept.pdf

That's a little light reading for you folks : D "The computed CD results for the simple rectangular bellmouth are worse" Right there in big letters on the last page, I knew I wasn't loosing my mind. I think the CFD and the countless race engines that use the round bell mouths confirm each other well.

The other conclusion was, as long as they are there, it is better than nothing, and only until the very last hp is required out of an engine is it very important how they are designed.

Maybe I need a new thread, intake manifold design for geeks...

 

[sparky1987]

I also went back through all of my notes from my high performance engines class. Where area decreases velocity increases.
So the square shaped runners do make sense when set at a taper or even straight on with a venturi inside the manifold plenum. It does allow for smoother less turbulant flow from the runners to the port inside the head when the runners are the same shape as the port.

 

[tkelly27]

You clearly wouldn't want to have a round runner mating with an oval shape on the cylinder head, that would be silly.

There is a lot more to it than just the the volumetric flow rate divided by the area of the pipe.

Flow rate through a squre tube
Reynolds number - Wikipedia, the free encyclopedia

Furthermore, you can easily make a round pipe the same area as a square pipe. I'm pretty sure where the transition between round and oval in a racing engine is based on where the flow losses switch between the round shape of the bell/throttle body to the oval shape of the inlet port, or even more importantly, what the positioning of the switching does to the frequency of the pressure pulses.

I know on the exhaust side in F1 the do stepping up in sizes to "tune" the torque enhancements to different RPM, and this happens somewhere between where they are an oval shape and a round shape. This is probably why they have to be formed in such a complex manor.

 

[sparky1987]

Well I've gotten it to the point where I like it and its ready for the flange. I think its turned out really well I just hope to be able to see what it can really do. The first picture is a picture with a 1g and 2g factory intake manifold.

 

[2slow4utsi]

Man I'd like to see some dyno results. I wonder if it will perform with other top manifolds.

 

[sparky1987]

I have really high hopes for this manifold. I can't wait to get it tested and get some numbers on it. It should come really close to what other manifolds do and with a little luck it'll be just a touch better.

 

[2slow4utsi]

I have really high hopes for this manifold. I can't wait to get it tested and get some numbers on it. It should come really close to what other manifolds do and with a little luck it'll be just a touch better.

I'd like to see some comparisons between this manifold and other manifolds on the market. Are you going to have anyone test this manifold on one of their setups and compare it to others?

 

[sparky1987]

After I get it finished yea im going to work on getting it tested and make any changes if any are needed.

 

[ckrell]

I know that this intake wouldn't even come close to fitting most peoples car here.

 

[sparky1987]

Almost looks like a 5.0 liter mustang design. But why would you want to run the throttle body on top of the head? I undertand the idea behind the design. But not the idea of putting the throttle body up that high.

 

[ckrell]

No intercooler, methanol pre and post turbo, and its the shortest route.

 

[turboglenn]

Very cool, nice to see people doing a lot of original stuff here lately (lik the other thread about first attempt at a SMIM above this one)

Looks similar to the stock style setupused on the ford 2.3 liter turbo engine's setup from either the turbocoupe t-buird or SVO can't remember which had it but i'm sure i've seen that setup before on the ford 2.3 engine anyway

can't wait to see it finished, and by the way i've had great luck in the past with pre and post turbo methanol and no intercooler, to be honest i can't remember other than the look of it why i went back to having a FMIC (at least that's whjy i post a lot of my stuff so i can look back and remember why i did something , musta bumped my head in that wreck that did me in a while back )

 

[ckrell]

First 3 designs were way to large like 6 liter plus. Tomorrow I'll have the inside and outside panel and TB flange weled on then I'll be able to get a more exact plenum size estimate and then see if I need to shape it down some more. I think it might be about 5.7L (a littel big still). Shooting for 4.5 to 5 liter.

 

[ckrell]

I finsh it yesterday, I think its around 300 C.I. its getting ran regardless. If its a little big side thats alright i'll just have to get to finshing my high compression 2.3L (seems like a good excuse anyways)

 

[92DSMErdrick]

Wozers, I guess you have to take the Throttle body off to take the valve cover off

 

[ckrell]

Wozers, I guess you have to take the Throttle body off to take the valve cover off

Yeah i will but I made sure that the flange wasn't having over the valvecover and I can even pull the two middle plugs with out removing the hotpipe

 

[sparky1987]

That's insane! Holy intake batman. I like seeing guys show their welding and fab skills that's why I started this thread. Nice job man good work. I wonder what kind of spool time you're looking at with something that large?

 

[ckrell]

That's insane! Holy intake batman. I like seeing guys show their welding and fab skills that's why I started this thread. Nice job man good work. I wonder what kind of spool time you're looking at with something that large?

Its about the same plenum size as JMF drag. Thinking 4500ish but my loose 8" converter should get me all the off the line torque I need to blow the tires

 

[99gst_racer]

I assume there's plenty of hood clearance for that? Are you going to run without an intercooler?

Nice fab work, BTW.

 

[GSLENK]

No intercooler, methanol pre and post turbo, and its the shortest route.

For all the help you have given me... ^^^

 

[ckrell]

I assume there's plenty of hood clearance for that? Are you going to run without an intercooler?

Not much hood clearance maybe 3/16" but I do have urethane motor mounts. Plan A is pre and post turbo meth no intercooler plan B is to add water to air intercooler

 

[99gst_racer]

Badass! Again, nice fab work. And I love the nozzle location.