My Suzi T500 Project *It's Alive Video*

Re: My Suzi T500 Project (exhausting!)

dcracing said:
Why not give it a try? I migged my first pipes, and it looks like those headers are mig tacked. BTW, unless I'm mistaken those sectioned headers are cut from straight pipe, not tapered.
You are correct that the work I have done so far is parallel pipe but from this point on it will all be cones. The pipe is 18ga wall thickness and tacked with mig. I will be welding the pipes up with oxy/acetelyne though. The cones will all be made from 22ga but all the tacking will be done with mig. Imho mig welded pipes look like crap but that's not to say they wouldn't be functional. If I could choose I would would be tig welding the pipes but I don't have access to tig at this time.
 
Re: My Suzi T500 Project (exhausting!)

Cool to know, then I could mig tack everything, then bring them to a buddy to finish with tig. Thx!
 
Re: My Suzi T500 Project (exhausting!)

mikewerx said:
Cool to know, then I could mig tack everything, then bring them to a buddy to finish with tig. Thx!
Yes, I actually think mig is the easiest way to get it all tacked together.
 
Re: My Suzi T500 Project (exhausting!)

Before you tack everything together with plans to get someone else to tig the seams ask them. Tig welding over mig tacks doesn't look good (the tig doesn't blend with the mig) and most welders don't want to do it
 
Re: My Suzi T500 Project (exhausting!)

You are correct. I only put two tacks on each section with the mig to hold everything in place then you can do the rest whichever way you want to ie; tack it with tig then grind out your original two mig tacks then go from there.
 
Re: My Suzi T500 Project (exhausting!)

Curious as to why you chose to do parallel wall headers? Tapered head pipes have long been known to provide better performance.
 
Re: My Suzi T500 Project (exhausting!)

dcracing said:
Curious as to why you chose to do parallel wall headers? Tapered head pipes have long been known to provide better performance.
I did not design the pipes so I can't answer that question. Someone else from this site did that using some fancy software that is way beyond my knowledge level. The actual part that is parallel is only 190mm long. Also the specs for the pipe are still being reviewed so things could change.

Nice to have another two stroke expert taking an interest in my build.
 
Re: My Suzi T500 Project (exhausting!)

This is looking great, John. I was also wondering about the taper on the head pipes but T knows what he is doing. Great to see you going forward with the project. I know how time changes our completition perception.
 
Re: My Suzi T500 Project (exhausting!)

Good to see you back on here Eric. Richard went through several different designs with the pipes, I am confident he came up with the best option although he is now reviewing the design due a possible oversight. I look forward to testing out the port work you did for me.
 
Re: My Suzi T500 Project (exhausting!)

dcracing said:
Curious as to why you chose to do parallel wall headers? Tapered head pipes have long been known to provide better performance.

Define "Better". :) we are talking mild mannered Clark Kent rather than hypersonic Superman in terms of powerband. Tapered headers tend to make for a lot more top end and less low down. We can easily generate an additional 10HP at the top end, but kill everything at normal street revs on this classic long stroke motor. That's why it has parallel headers - at this point....
 
Re: My Suzi T500 Project (exhausting!)

Tig welds over mig tacks look fine when i do it ;) looks good man keep it up
 
Re: My Suzi T500 Project (exhausting!)

You have data to the contrary? I'd love to talk to you about that. I've heard all sorts of cliams and comments from people that know and people that think they know that suggest that tapered headers work well at low revs, but I haven't seen one so far.

That doesn't mean they don't exist, but I haven't had one that did. Maybe that's because the only time it's typically worth the fab effort is on a high end (revs) pipe and maybe it's other dimensions that are causing the loss of low end. I'm always learning and ready to hear what other have learned.
 
Re: My Suzi T500 Project (exhausting!)

I know through experience that a longer header produces better low and mid range power at the expense of some top end.While I cannot prove it I believe that the tapered header allows a smoother transition from head pipe to divergent cone which allows for a smoother power transition when the motor comes on the pipe. I build relatively fat pipes and without a slightly tapered header the transition to divergent cone would be too sudden and would result in either a too steep a divergent cone angle or too much total length.
 
Re: My Suzi T500 Project (exhausting!)

That makes sense to me and I agree that with a large divergent cone angle, it's easier to use a tapered header. I just can't get the simulation software to support it though. There appears to be a fine line where sonics and gas flow cross lines. For example less than a certain angle of change the pulses are weak and above a certain point, wave separation and poor flow seem to hget in the way.

Remember when 4 stroke tuners went for 3 to 5 angle and then tried full radius seats? As I recall it, full radius turned out (all puns intended) to not flow as well as the sharp angles. I didn't follow up on that to see if anyone worked out why air likes changes in direction, but it's analogous to this situation I believe. That's all probably past my pay grade though.

On a kart motor I found that when you get deep into the over rev zone, the best pipe appears to be one that has many different cones with small changes in angle form one to another - almost a continuous curve. When I tried the same approach on lower rev motors, results were disappointing - probably because the pulses have insufficient energy for that to be a factor. What that did was to stretch the curve way out at the right after peak power which is where these guys are going. Next step is to simulate teh pipe temperature effect of leaning out the carb as they go down the straight. That is having an effect on where that over rev reaches.

And that's where I'm at right now. For say an RD motor peaking at 10-10.5 tapered headers and fat pipes appear to work nicely. On a street RD or GT500 with a peak at say 8500 (RD) or less (GT) there appear to be advantages to parallel headers and simple designs.

Of course a long parallel header has surface drag that acts almost like a smaller pipe as it goes down the length, and a shallow taper acts to balance that out to "act" more like straight pipe at high revs where this stuff matters most. At least that's how it looks at the moment.

On John's pipe I started with half a dozen well documented pipes and tried them with his port dimensions and a few assumptions. Then I generated a few designs in Bimotion and using the Blair algorithms, and tested those and then started to develop from there - trying different lengths and diameters on different parts of the system. There is surely more in there to be extracted, but there's only so many hours in the day.....
 
Re: My Suzi T500 Project (exhausting!)

I like this discussion, learning all the time. Keep it up!
 
Re: My Suzi T500 Project (exhausting!)

teazer said:
That makes sense to me and I agree that with a large divergent cone angle, it's easier to use a tapered header. I just can't get the simulation software to support it though. There appears to be a fine line where sonics and gas flow cross lines. For example less than a certain angle of change the pulses are weak and above a certain point, wave separation and poor flow seem to hget in the way.

Remember when 4 stroke tuners went for 3 to 5 angle and then tried full radius seats? As I recall it, full radius turned out (all puns intended) to not flow as well as the sharp angles. I didn't follow up on that to see if anyone worked out why air likes changes in direction, but it's analogous to this situation I believe. That's all probably past my pay grade though.

That's what I was insinuating in another thread where I discussed re-shaping an R5 head. In some cases air flow (charge in a combustion chamber) seems to like a hard transition rather than a radius. Not always the case as I'm sure you know, knife edges are not good in inlets etc. My belief is that hard radius' are good where the air flow approaches from the side and not good when the flow approaches directly at the knife edge if that makes sense.

[/quote]
On a kart motor I found that when you get deep into the over rev zone, the best pipe appears to be one that has many different cones with small changes in angle form one to another - almost a continuous curve. When I tried the same approach on lower rev motors, results were disappointing - probably because the pulses have insufficient energy for that to be a factor. What that did was to stretch the curve way out at the right after peak power which is where these guys are going. Next step is to simulate teh pipe temperature effect of leaning out the carb as they go down the straight. That is having an effect on where that over rev reaches.[/quote]
I haven't done much with low rev motors but I imagine when designing an exhaust for a long exhaust duration + low rev motor, it would be tough to find room for a long enough pipe. If you have the ability to change curves you might be able to move power around a bit through judicious use of advance

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And that's where I'm at right now. For say an RD motor peaking at 10-10.5 tapered headers and fat pipes appear to work nicely. On a street RD or GT500 with a peak at say 8500 (RD) or less (GT) there appear to be advantages to parallel headers and simple designs. [/quote]


I find it very difficult to sim transfer ports, probably because I haven't enough experience with the program, but I *believe* you'll find that in real world applications RDs (air cooleds) don't like fat pipes because they don't have the transfer volume to support a large volume pipe. Stand to be corrected there though

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Of course a long parallel header has surface drag that acts almost like a smaller pipe as it goes down the length, and a shallow taper acts to balance that out to "act" more like straight pipe at high revs where this stuff matters most. At least that's how it looks at the moment.

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This is where it started I guess. My opinion is that a parallel wall header would never be superior. Again I stand to be corrected. I look at it like this, if I designed a hypothetical pipe off the top of my head for 190* duration and 9500 rpm I'd probably be looking at a TL of somewhere around 850mm, give or take. Of this maybe 270mm or so will be header. That much parallel wall will have a significant effect (flow resistance) on the movement of the gasses in both directions which can fairly easily be mitigated with the construction of a tapered head pipe I also design for minimum taper changes within the sections of the divergent cone, less than 3* difference per section ideally. Were I to run a parallel wall to the divergent cone I'd have a severe change of angle there, much greater than my chosen maximum. Obviously with a short header the parallel vs tapered debate would not be a factor for me, but short header= higher peak=less low and mid=not happy me

[/quote]

On John's pipe I started with half a dozen well documented pipes and tried them with his port dimensions and a few assumptions. Then I generated a few designs in Bimotion and using the Blair algorithms, and tested those and then started to develop from there - trying different lengths and diameters on different parts of the system. There is surely more in there to be extracted, but there's only so many hours in the day.....
[/quote]
 
Re: My Suzi T500 Project (exhausting!)

This is great, helping me understand the 2stroke pipe (to a small degree anyway) ::)
 
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