Dyno testing various shapes and lengths after headers / extractors. On a na 4age Help me make more vids, grab some merch: teespring.com/stores/garage4age Insta : @garage4age @Garage 4age
Was planning on doing some more open header tests, but far too loud. Especially with the megaphone. Testing with a muffler is more relevant to what im doing, and guessing most people watching this. The real time graph freezing, was the pc/sofware recording the screen frizzing out due to the noise. I'm having to fight the odd zombie now after awaking the dead. The megaphone makes a fine weapon for that. Anyway looks like heading in the right direction with megaphone and downsizing collector outlet. Thoughts?
I think moving the the start of the megaphone closer towards the collector would improve scavenging as the expanding exhaust gases would increase "vacuum" at that point. Much like the Venturi in a carby?
What about calculating a "proper" megaphone collector? The lenght would probably be near 350mm +/-20mm and choke section around 46...49mm (length 25.4mm). Megaphone start 47-50mm and end 67-71mm, with reverse cone length 31.8mm and end to 58-62mm. These are just very rough numbers, just as an example. Your test proves the megaphone collector seems to work, even tho length and other measurements may not be near the "optimal". I know atleast Pipemax can be used to calculate e.g headers (many designs) and the whole exhaust system length or just the collector. If you give all values required to calculate headers/collector , I can send you the measurements Pipemax gives - for testing purposes. Would be very interesting. But its not really an expensive software if you work with n/a engines, and do cylinder head work, intake manifolds and headers. But I want to thank you for the amount of testing you do. It's interesting to watch!
@@willdavidson4599 It was like this in the last run in vid, didn't like it. Although good chance that the choke point was too big for it to work. Hence why the first megaphone setup tapered down before going back up
@@juhonmoottoripaja2443 It isn't actually too far off those numbers. the choke point is 50mm od, so 47mm ish id. the megaphone angle probably isn't too far off either. is roughly 7 deg included angle. just goes up a lot bigger, as the plan was to cut it down to see what effect it had. would be interested to see what the pipemax program spits out. email if you like garage4age@gmail.com
It would be logical that the first cone would help exhaust scavenging, but reverse cone is a surprise! Thats basically two stroke engine exhaust haha. I believe the longer the first cone, (less angle) the flatter the dyno result. (longer scavenging duration). The same goes in building the exhaust for two stroke. And same applies for reverse cone , but, reverse cone is here to build back pressure. Having larger angle should help scavenging on shorter range of rpm with better peak hp... and reverse cone too, but i somehow doubt that reverse cone lol. Reverse cone builds backpressure over the certain rpm range. Maybe when the valve overlap happens you could actually have some gains, at higher rpm? I was sure it could help (without reverse cone) to flatten some bad rpm range. And placement is crucial. Closer to the head favors higher rpm while lower rpm usually suffers. And vice versa. Your placement is pretty far, which is good for lower rpm. Tho this does apply for two stroke, i dont know how 4 stroke behaves, so your video is pure gold :)!
@@apesplanet3301obviously small changes arent supposed to give super big changes, the main idea is just to test what changing a variable does to the overall equation.
These videos are so good and unique, that it makes me wonder - what morons keep putting thumbs down? We should be encouraging channels like this to shine!
This is exactly the kind of content I need for my soul 😆 Thanks for going to the effort, I'm all about the back to back testing. I may try a similar style collector extension myself.
I'm glad you put Brick in the intro, I have some much more energy now that I don't have to do the LOUD NOISES drill every time I watch one of your videos...
Hi you're video are awesome. Could you put a turbo on the exhaust of naturally aspirated engine ? I've always been wondering how big is the flow restriction induce by the turbo (which is the normally compensated by the boost on the intake side but anyway). Cheers
what i gathered from watching your video 1. not enough breathers = burning oil 2. your engine power output is not restricted by the exhaust. 3. you could have logged the AFRs on every run to see how much more or less air is flowing from the exhaust. I suggest that you do all the power mods like cams and turbo that will make your exhaust the restriction and do the test again and you will see how each affects power output
1. Engine was built from 3 worn out and broken engines. only new parts in it were the bearings. not a breather issue 2. That's not the point of the video, 3. power curve shows the same thing. AFR change with the same injection rate is the poor mans dyno. if goes leaner you are making more power I wouldn't be testing megaphones and collectors then. I'd be testing how restrictive the exhaust is Some things need to work with other things, but good science is testing something without the influence of another thing. If went from a restrictive exhaust to a non restrictive exhaust, that happens to have a megaphone or different collector. there is no way to know where the gain / loss came from
@Garage4age how do you know for sure? 120kw is a very very good power output for a 4age na even at this power a 2inch system would yield the same results.
@@joshghazi big exhaust simulates exhaust ending after headers and collector section. if tune those parts right without restriction after them. can retain and even gain bottom end power with big cams (as well as the top end gains) over a stock cam engine. this engine makes more power everywhere than a stock engine and it runs 284/278 cams. It makes good power as it has all the good bolt on parts from my good engine which makes over 160kw
If I see all the runs, it seems to me that the pipe is actually a little large on diameter, for the size of the engine and the output, 2.5" IMO is killing velocity and there for scavenging, I do believe that 2.25" is the magic bullet but make that pipe section from the collector to the megaphone a little longer for about 8", and the transition from the collector to the 2.25" as smooth as possible so the velocity increasy is more effective and there for the scavenging, you will need to see what will happen to Cyl #4 AFR.
PLEASE DO AN X to Y PIPE FROM THE BOTTOM OF THE HEADERS, X THE TWO BANKS TOGETHER! In theory should help scavenging? It’ll be a bit of work but I’m intrigued to see the power, sound and response differences!
I would think a more traditional shorter 4-1 header and a 2” exhaust with a muffler way out back would be the best real world solution. More bottom end and midrange with higher exhaust velocity and some scarification of peak numbers but less than a 4-2-1 header. Check out thecarpassion channel for an interesting look at intake lengths on the Miata.
If you watch my previous videos, where i tested the 60mm exhaust. this isn't really the case. It lost a lot of power down low with 60mm all the way and a muffler at rear. the front section to the first muffler and placement is critical to making the low end power
sometime i may do more on it when get time. is a lot of fab work and time. in the meantime ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BV086sZarcQ.html that video one of the headers has a step. but also has a different collector design. the "big" headers in my videos also have a step in them
looks like the megaphone is helping a little overall. and the 2" choke point helps the bottom end. As when changing to the 2.5" section top end is the same, but a loss down low. I'm interested to see how small can go on the "choke point" before it losses up top. or stops gaining down low
@@Liveforeever way i understand it, is its some kinda wizardry. that lowers pressure on the engine side of the choke point. so should be able to run a smaller choke point to increase scavenging. the angle of the megaphone has to be correct for it to work
@@Garage4age good advice, might do, they aren't too expensive, might remove the terrible resonance noise while at it, I'm not too concerned with power as it has enough grunt down low for general driving, but I really don't like what hollowing out the cat did to the engine sound.
Have you tried a straight 2.0 or 2.5 inch straight pipe? Maybe a smaller diameter would make better work of the exhaust pulses, 3" and megaphone seems like too wide for that engine to take advantage of
I used to run the straight pipe off the collector down inside the cone section to create "antireversion" Running just the cone without the pipe protruding into it makes more power.
my current headers have a single step. the atlantic car here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bWNdVy5bNBA.html has double stepped headers. I think theres more to it than just stepped headers
If you have the gear and skill to investigate these difference with an added bonus of ability and patience to film these findings to be able to share them to everyone is quite an accomplishment! It's definitely worth the time and job to show what doesn't work so many other people will be able to spend the time making what gets the better result of if it's only a little bit more.
@@HassanEido1 Thanks. My good engine will go back in at some stage. I'm still waiting for some parts to be machined to test, which is the whole reason this cheap worn out old engine is in the car.
There are formulas for the header, expansion section and the reducer section. I think these were in the "Two Stroke Tuner's Handbook" by Gordon Jennings. The book is long out of print, as far as I know, but a pdf can be found online. The lengths all depend on the tuned RPM. The diameter is related to the engine's displacement, how much air has to be moved. While it can be used over a range of RPM, it REALLY comes on strong at the tuned RPM. Often a muffler section is built over the reducing section, seen as a cylindrical pipe starting at the weld between the two cones. When run at resonance, with a 2-stroke, some of the air/fuel mix is drawn through the cylinder out into the header, then before the piston closes the exhaust port, which is taller, and therefore closes after the intake port, the air/fuel mix in the header is rammed back into the cylinder before the exhaust port closes, actually giving a supercharged effect.
Always interesting so watch your vids. Have you tried anti-reversion chambers on the exhaust? Also a 4-2-1 headers is claimed by many to be superior. Had any thoughts on that?
yeah.... here in sweden as you know they reign supreme :D there is power in the midrange to be had with 4-2-1 for sure .... otherwise motordesign wouldnt run them :D
@@magnusdanielsson2749 4-1 will make more power as its design favours the top-end. 4-2-1 has a broader effect, so your midrange will be fatter but your top end won't be improved quite as much as with a 4-1.
Unexpected results 5kw is a fuckton, seems like the 2.5" section normalize the flow entering the mega. Could you try making the front section longer and maybe putting a muffler before the mega with and without a front section that normalize it? To see what the flow thinks
Dude this is the best video I’ve seen on your channel! It just reminds me of how much we missed in the 90s and early 00s. It’s so amazing that we are still finding HP without technology except maybe the technology of making discussion and sharing knowledge easier. I mean I’m doing an engine swap I did 20 years ago (H series Honda into hatch) and there have been countless low tech improvements!!! It’s so amazing!
Im trying to maximize mid-range power on a stock 4age big port. Should I just use stock runner size and lengths? Would longer/larger runners only decrease my power below 6krpm? I'm trying to figure out my best setup between stock, 20v ST header, and TRD 4-2-1
Maybe you would try a few different header length and diameter setups? Like building an adjustable length header. F.e. starting off with a desight which would let all 4 go to collector as soon as possible, and just add extensions and try which would be best. Maybe even through the hood setup. Cheers for such a great videos, mate.
Ive started to build some new headers, to drop in the same place. length will be the same, but will be making a few other changes. may do length at later date.
A horn muffler might not be as good as a reverse-horn muffler. What I mean is that as the gasses cool from the engine they contract. So going into a horn means that they need to lose energy and that energy will come from the engine power. Many new cars therefore have a restriction just before or after the muffler to keep the pressure up and flow-rate going faster.
Interesting as always. The headers manifold is the best which you always use, right? What diameter they are? Never thinked that a 2stroke looking pipe could be good on a foustroke engine.
so generally in your car is better small header (35mm) with big pipe (3"), than viceversa, 38->44mm header with smaller pipe (60mm) . Are there some engine config where the big header and small pipe would work?
Great video, you could try that setup but 3", 6", 9", 12" between header and that pipe to see if you can tune to get the negative pressure wave back to the exhaust port at the right time. great results. Thanks
Yeah definitely the part that responds best to changes. Will probably try a few more things, to get it closer. but really need to wait till the good engine goes back in to get it dialed in.
Great video..megafone (gern pipe) works..just a lot of work to try it out but i think its worth it..i didnt get it..does a short collector or long work better.. maybe try putting a smaller megaphone in the back of the car and a muffler and a longer collector pipe..this would be considered real world use i guess..
So it's about like an expansion chamber but for multiple cylinders? I thought about something like this, but for the down pipe on a turbo, say if it's a 3" outlets, have about 4-6" of 3" pipe, then go to 4" maybe 5" for about 3" -6" possibly 8", then backto the 3" with up to 180° of bends , probably it would be best to have the bends in the larger pipe! Be at a bend has the same effect as a smaller pipe, dropping diameter over about 2-3", but I guess the same pipe could fit on a header collector, The swirling chaos from a turbo, can likely take advantage of the larger pipe to get the flow in order as it is reconstructed as the pipe diameter is reduced, it can be difficult to build if tooling is a issue. I would like to see it tested !! Maybe it could offer gains over a open turbo, and a standard head pipe,
Dude, again, fun to watch the fab and crazy to see the results that I didn't expect at all. Since you've been testing the increasing/decreasing diameter theory, think you could make a megaphone that transitions over a longer distance, but still doesn't become ridiculously large? Like 3"-5" but 4 feet in length? I see how hard it is to fab them, so I know it's a pain, but your "subscribe" message etched on this one made me subscribe, and I don't subscribe to anyone usually lol
Yeah can probably run a little bit lower angle. this one is getting towards the max it should be. once i'm happy with a setup. plan was to make an oval item that fits under the car and hope it still works the same.
Really nice and informative video's! Try a cone just after the collector, with different reduction diameters. You should be able to pick up a few kW and smoothen the torque curve....
