Thread for naturally aspirated manifold design - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 01-01-2016, 01:03 PM   #41
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

That is 11.5" runners so about 15" to the valve.

The next step is to cast the intake ports. I have some high viscosity brush on silicone coming for that. After that, an expanding foam pour inside the engine bay + 3d scan will give a really good idea of how much space there is to work with and will help determine what can be fit in the engine bay.

I think .25" and .5" spacer plates would be a good way to fine tune runner lengths.
asmasm is offline   Reply With Quote
Old 01-02-2016, 12:02 AM   #42
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

This assumes a few things. First, no way to include runner taper in the calculation. I fudged it since my runners are a linear interpolation of two shapes- I picked a value in the middle. Second, it needs to be given a speed of sound, which is dependent on the air temp. The suggested number was over 200F, which seems really high, but I am using it since that seems to generate numbers that match practical examples.

Code:
Runner  3rd wave peak	4th wave peak
13.5	6061.607372	4546.205529
13.25	6146.228874	4609.671655
13	6233.246498	4674.934874
12.75	6322.76348	4742.07261
12.5	6414.88907	4811.166803
12.25	6509.73898	4882.304235
12	6607.435867	4955.5769
11.75	6708.109865	5031.082399
11.5	6811.899162	5108.924372
11.25	6918.950633	5189.212975
11	7029.420531	5272.065398
10.75	7143.475251	5357.606438
10.5	7261.292167	5445.969125
10.25	7383.060549	5537.295412
10	7508.982581	5631.736935
9.75	7639.274477	5729.455858
9.5	7774.167726	5830.625795
9.25	7913.910459	5935.432844
9	8058.768975	6044.076732
8.75	8209.029435	6156.772076
8.5	8364.999747	6273.74981
8.25	8527.011672	6395.258754
asmasm is offline   Reply With Quote
Old 01-02-2016, 03:42 AM   #43
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,999
Total Cats: 1,466
Default

How much boost will it be able to handle
aidandj is offline   Reply With Quote
Old 01-02-2016, 10:24 AM   #44
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

Somewhere between some boost, and no boost.

Another thing I'm not sure of- air pressure affects the speed of sound- which would mean boost skews the numbers. For example, at 50% humidity the speed of sound at 85c, at atmospheric pressure, is about 1300 feet per second. At 200 kpa it is 1270 feet per second. That difference is enough to move a third wave peak about 200 RPM.

The prediction math gets wonky when the conditions they are supposed to operate in are dynamic and you don't know what a good baseline set of numbers to use are. I am having a hard time believing it translates to actual use accurately since the wave tuning would be shifting around dramatically based on a 50F change in intake air temp.
asmasm is offline   Reply With Quote
Old 01-02-2016, 10:39 AM   #45
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

someone take a VICS manifold, and mod it so it's long/short runners.
Braineack is offline   Reply With Quote
Old 01-02-2016, 11:01 AM   #46
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by Braineack View Post
someone take a VICS manifold, and mod it so it's long/short runners.
Yes I certainly agree making the runners longer would be very simple. Even small changes would take significant amount of dyno testing to quantify. Intake tube length will have a significant impact on the results as well.

Can you replicate any existing data with the OEM manifolds?
Alternative is offline   Reply With Quote
Old 01-02-2016, 11:08 AM   #47
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

Based on the dyno charts I have seen, I think the square top lines up pretty well with the predictions using ~1300 feet per second for the speed of sound. It is hard to tell looking at an isolation dyno sheet, what part is the intake manifold vs any other part of the system.
asmasm is offline   Reply With Quote
Old 01-02-2016, 11:10 AM   #48
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

Quote:
Originally Posted by Alternative View Post
Yes I certainly agree making the runners longer would be very simple. Even small changes would take significant amount of dyno testing to quantify. Intake tube length will have a significant impact on the results as well.

Can you replicate any existing data with the OEM manifolds?

it's already setup for it, you just have to mod it, but not gut it.
Braineack is offline   Reply With Quote
Old 01-02-2016, 11:30 AM   #49
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by Braineack View Post
it's already setup for it, you just have to mod it, but not gut it.
Right a spacer.

The cost of a single 1" CNC spacer would be significant for something that would likely have a negative impact. More than 1" may have clearance problems.
Alternative is offline   Reply With Quote
Old 01-02-2016, 11:34 AM   #50
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

A spacer for short term dyno testing could be made from cheaper materials. You might even get away with marine grade plywood and a phenolic gasket to protect it from conduction.
asmasm is offline   Reply With Quote
Old 01-02-2016, 11:38 AM   #51
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by asmasm View Post
A spacer for short term dyno testing could be made from cheaper materials. You might even get away with marine grade plywood and a phenolic gasket to protect it from conduction.
Thats not a bad idea!
Alternative is offline   Reply With Quote
Old 01-02-2016, 12:12 PM   #52
Senior Member
iTrader: (4)
 
Join Date: May 2010
Location: Cedar Rapids
Posts: 674
Total Cats: 29
Default

Wouldn't he mean removing the wall on the upper and leaving the lower?
vteckiller2000 is offline   Reply With Quote
Old 01-02-2016, 12:34 PM   #53
Senior Member
 
Join Date: Apr 2011
Location: Hollywood, FL
Posts: 525
Total Cats: 18
Default

Techno Toy Tuning makes an adapter so you can bolt on 4AGE ITB's onto it. I have one for my set-up. This could be used as the basis for your two part manifold taking the most difficult part of the manifold making process (IMO) out of the equation. You can then build upper sections with different lengths or spacers as you mentioned earlier. It would also stave off some of the heat directly off the cylinder head. It's not incredibly cheap at $300+shipping but not prohibitively expensive either.

My set-up uses the supposed 42mm throttles with 4" air horns for a total runner length to the head of roughly 11". Compared to a VTCS manifold on a dyno about 6 months later but in the same weather conditions roughly, there was a ~2% loss in torque up to about 5500rpm and then the ITB's took over. And I saw a max MAP reading of 108kpa. So Aidin, it could probably take 8kpa of boost at least.

The tune is not great and I believe the VVT was not working correctly either. It never worked correctly under normal driving conditions since it's a VVTuner and not native VVT control. Will be finishing up a new Megasquirt that has native VVT control soon and we'll see if the torque readings get better down low with actual VVT control on the ITB's.
hector is offline   Reply With Quote
Old 01-02-2016, 12:42 PM   #54
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

interesting idea, using an ITB adaptor as a manifold part. I would have to compare that to the cost having a run of aluminum flanges machined. The aluminum flanges would have the added benefit of being something I could design for easy bonding to carbon.
asmasm is offline   Reply With Quote
Old 01-02-2016, 12:45 PM   #55
Senior Member
 
Join Date: Apr 2011
Location: Hollywood, FL
Posts: 525
Total Cats: 18
Default

I meant just for testing to see what the effects of runner length are. It seems as a kit it would be prohibitively expensive. And TTT makes them in batches so they are not always available. Of course there are other ITB manufacturers that have flanges/adapters but who knows what those cost too.
hector is offline   Reply With Quote
Old 01-02-2016, 12:54 PM   #56
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by asmasm View Post
interesting idea, using an ITB adaptor as a manifold part. I would have to compare that to the cost having a run of aluminum flanges machined. The aluminum flanges would have the added benefit of being something I could design for easy bonding to carbon.
Do you have any experience bonding carbon to aluminum? Making carbon tubes is pretty simple but making something that is able to withstand the enviroment is significantly more difficult.
Alternative is offline   Reply With Quote
Old 01-02-2016, 02:15 PM   #57
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

My plan is a flange with a large amount of overlap between the carbon and the aluminum. Something like this:



With good surface prep and the correct epoxy I don't see there being any problems.
Attached Thumbnails
Thread for naturally aspirated manifold design-80-img_9884_5e631f8b7c9ca45fd037e569d64caebb016d50e7.jpg  
asmasm is offline   Reply With Quote
Old 01-02-2016, 02:21 PM   #58
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by asmasm View Post
My plan is a flange with a large amount of overlap between the carbon and the aluminum. Something like this:



With good surface prep and the correct epoxy I don't see there being any problems.
That is the AIR manifold that was sold by Endyn for a short period. Even with high demand they were not able to produce reliable manifolds. The company that built the AIR manifold was a manufacturer that was very familiar with bonding carbon and aluminum and still was not able to do it reliably.
Alternative is offline   Reply With Quote
Old 01-02-2016, 05:44 PM   #59
Senior Member
Thread Starter
iTrader: (1)
 
Join Date: Jul 2012
Location: durham NC
Posts: 767
Total Cats: 115
Default

The only thing I can see being tricky is dealing with thermal expansion being different between aluminum and composite. Otherwise, it is just a matter of surface prep and picking the correct structural epoxy.

You could also drill a hole through the flange and the and the carbon and then press fit a short aluminum dowel for mechanical interlock.

The throttle body flange could be made from carbon fiber or aluminum, which ever is cheaper and easier. It won't see anywhere near the same amount of heat as the flange at the head.
asmasm is offline   Reply With Quote
Old 01-02-2016, 08:05 PM   #60
Junior Member
 
Join Date: Jan 2015
Posts: 272
Total Cats: -22
Default

Quote:
Originally Posted by asmasm View Post
The only thing I can see being tricky is dealing with thermal expansion being different between aluminum and composite. Otherwise, it is just a matter of surface prep and picking the correct structural epoxy.

You could also drill a hole through the flange and the and the carbon and then press fit a short aluminum dowel for mechanical interlock.

The throttle body flange could be made from carbon fiber or aluminum, which ever is cheaper and easier. It won't see anywhere near the same amount of heat as the flange at the head.
Not just the expansion, maybe more significantly the vibration. You will want to think about a brace similar to the OEM manifolds. You will also want to figure out a way to prevent galvanic corrosion between the aluminum and carbon. You may be able to use some type of anodized coating on the aluminum pieces.

Graphite fiber has a negative coefficient of thermal expansion, but can be adjusted with specific epoxies to near zero. So the thermal expansion of the Aluminum will be more of a concern. There are semi-flexable bonding agents you can use to adhere the carbon to the aluminum but the vibration will cause fatigue over time.
Alternative is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Miata Garage Sale (Engine parts, Suspension, Interior, Exterior) vehicular Miata parts for sale/trade 24 06-08-2016 06:53 PM
BEGi Bell Engineering Group's terrible intake manifold NwaR Bellengineering - Miata Accessories 102 02-04-2016 04:16 PM
93 parts/ 94 engine parts kww502 Miata parts for sale/trade 5 01-17-2016 03:24 AM
Various Turbo Components VRRMPSH WTB 0 12-23-2015 09:15 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:33 AM.