Re: Re: Re: pictures
 

That's seemed to me... will try some things.... one will be a metamorphosed RR12 who changed the powerband trying to find brutal mid and high rpms losing some of the low-end that has.

and the other will be a NS12 or RS12 with a very close gearing. The RS12 loves to whine a lot.

What kind of gearing tried you tried on the MTX3 (if you still use it) in the warm-up race... planning to carry 20/25, 20/26 and 21/27 for pinions on 0.8 gearing. Probably the 20/25 will be a little short, but need to try it. 20/26 with 58/53 is mine stock gearing for mine local track, a little longer than Ft. Myers (900Ft long with some ample turns and two hairpins).

One thing that scares me the sh*t what is the stinger size on the exhausts is the maximum under ROAR rules? 5 or 5.2mm? All mine pipes go at 5.1... and need to know if need new pipes. :cry:

ROAR rule is 5mm max. on the stinger. I wish they'd move up to 5.2mm though. My favorite pipe (so far) uses that size stinger.

I have been trying to modify engines by myself, with out guidence. They end up being fried. (literally, they pop!!) How do you guy measure your cuts (leangth+depth)? Is there a tool? Is there a book that I can get that explains the correct process. I want to learn how to do this. It is very interesting to me. Please help. (Most of the engines that I modded were really really cheap. I don't have a lot of cash, but you have to start some where.)

Later,
-Dust

Hey Dust, are from revelation, the guy who is working in shop?
If you are, I will come one day ( may be this weekend) and I will try to help you with that.

I used to work there during the summer. I got to school in Pasadena. It was would be hard to keep my job while playing 3 sports and traveling back and forth. I live in Upland, so I have to wake up really early to get to school on time. It would be a real mess if I had to work during the week. Tell me when you will be going, and I will try to meet you there. I am currently running a non- modded MR-12. I have a brand new NS12 3 port, that is still in the box. I might mod that one. The NS12 is pretty fast as is, i might modd it, I don't know yet.

Thank you for your kindness,
- Dust

I might be there late afternoon on Sunday, if not I will send you PM with other day or we can meet on CP ( I am planning to be there tomorow).
Edward

Hey TG (or anyone) you got any info or advice for modifiying the taper on the bottom of the sleeve? I'm not sure what a steeper taper does as opposed to a less steep taper.

I do very steep taper there, right under the exhaust port. It is free up piston. Under the exhaust port we don't need any sealing, so the more we take out-less friction we have there. It is only guyding piston to go straight. Sorry can't release phisical numbers-this is one of the numbers can be disclose.
You need to try, lap it little by little and will see the difference, once you got overlaped-you will notice the piston will hit top line of exhaust port on sleeve. When you got to that point, just mesure it and do little bit less.

Thats cool I was a little stumped and needed a hint (which you provided)


Thanks, Never thought to mess with exhaust I've been playing with boost and transfer. I will give it a try........too bad its 28 degrees outside so no testing for a while:cry:

ps - Can't wait to see how the PS12 does at the winter Nats - Good Luck

You are very welcome. Any questions I ready to answer, even some real numbers can provide, beside some key numbers.
I can't wait to see how PS12 will perform too ;)
Thanks for wishing luck to us.

Fellow modders.....I was wondering when you adjusting intake port timing do you raise the top of the port or lower the bottom. So far I have only raised the top....just was thinking what would happen if I lowered the bottom.

I would love to help, but realy didn't understand what do you mean by "raise top " or "lower bottom"
In induction we always talk about when it is open and when it is close ( duration can be calculated or mesured).
So , do you advanced in opening or closing? What power band you want to have from your engine?

Ooopss!! Sorry for the confusion.....I'm talking about the transfer ports opening on the sleeve....So far to increase transfer timing I have been grinding the top of the transfer port (top meaning edge of transfer port opening closes to TDC). I hope that mad it a little more clear.

And my question is...Would I need to grind away at the bottom of the transfer opening for any reason (bottom meaning edge of transfer port opening that is closes to BDC).

I got question. Don't touch botom of ther port-it changes nothing. If you want to change timing just cut the top line of sleeve.:nod:

In general terms, what performance change do you enhance if you increase induction by advancing opening or retarding closing of the crank opening.
I.E. advancing opening = more torque
retarding closing = more top end
Or is it the opposite.
Same way with transfer ports, what effect does it have to rise the port or lower it.

AFM

It is about right, but you have to remember of resonble limits and balance-meaningif you keep opening to any of the way try to achive one of the parameters and cross the limit line-engine will just stop perform at all.
Transfer port has to be at certain opening, to have enoough time to transfer all mixture to combustion chamber. Exhaust opening is more complecated. lower exhasut-longer dwelf time-more torq, higher exhaust-smaller dwelf time, less torq, bu higher RPM. Also difference between exhaust and transfer will dictate your pipe performance. There were alot of studies done to find the best suitble difference and so far is about 40 degree. In our aplication little bit different due to our pipe design ( two cycle).
\ Got go, will be later.
Didn't finish.

thanks TG

Thanks TG, think you have a plane to catch...we'll keep this interesting class for some other time....good luck...
AFM

Top Gun 777...can you explain that a little more. I taper the bottom of the exhaust port but not sure if you mean the same. Do you have pictures or drawing to illustrate that? Thanks

In my post I was meaning to make bigger taper in diameter of sleeve, not the exhaust port it self.
i don't have saner to make pics of drawing, but will try find one, after winter nats.

So you mean inside the sleeve so there is slight gap between the piston and the sleeve below the exhaust port?

Hey TG do I buy the P/S/conrod set directly from you. I want to try one in my MR12(3 port) or my NS12 (5 port). PM me

later

Yes you are right. On my P/S sets I have realy big tapering below exhaust port.
My P/S sets were use in Ft. Myers and you can check with Stefan abiout performance, he was the one of the racers who used. He loved it so much and reserved more from me.

Yeh, you can order from me directly. I expectin to have batch comming soon. Not too many left, but I still have some.

EDDIE!!!!!!!
 

Where are you??????????????????

Hey guys,

I'm looking at the package of my mugen P/S set for my MR12. The package says MR RS NS RR...If these engines use the same sleeve what makes the power different?..Is is carb? crank?

What they are telling you is that it "fits" any of those Nova based engines, but it has probably Mugen's port timings, so in effect if you put that sleeve into lets say a RS you are timing it under Mugen's layout, but we still have the issue of crank induction timing which could be different from engine to engine.
I had an experience rebuilding an RBX12 with a Novamega P/S set and tried it with RB's crank and the engine had more torque, when I tried it with the Novamega crank, the engine had more top end
AFM

what are some good numbers for a 4 port .21 to achieve max lowend?

this is my first time playing with timing and below is the numbers from the pos 4 port HPI .21BB I'll be practicing on, I have 4 of these so I can do all the damage I want in the quest for knowledge ;)

• INDUCTION—open 35 degrees ABDC (above bottom dead center); close 41 degrees ATDC (at top dead center); duration 186 degrees.

• EXHAUST—open 81 degrees BBDC (below bottom dead center); close 81 degrees ABDC; duration 162 degrees.

• TRANSFERS—open 67 degrees BBDC; close 67 degrees ABDC; duration 134 degrees

so what way should I go for the HPI to get the most lowend while still giving a little more room on top?

I'm thinking of pushing the induction closing to 55 resulting in a 200 duration and opening the exhaust duration to 170.

Does that sound close?

If you lengthen the exhaust duration you will lose torque and gain top end power. When I tried increasing the intake (sleeve)duration, like 8* or so, I thought it had more power everywhere. if your induction port opens sooner it shuld have more bottom end power, while if you grind on it to stay open longer it should have more top end power, I thought like a 210* duration was good. You can also change your combustion chamber's shape, the taper, band width, radius of the bend/angle, and can put some grooves in it to get the fuel/air to mix better and burn more powerful b/c the rich spots shouldn't be as bad. I have only ran .12 engines so the principles will be the same for .21's but the numbers might differ.

Thanks SlobbaTech.


Here's some of my other motors for comparison.

S7:

• INDUCTION—open 43 degrees ABDC (above bottom dead center); close 54 degrees ATDC (at top dead center); duration 191 degrees.

• EXHAUST—open 85 degrees BBDC (below bottom dead center); close 85 degrees ABDC; duration 170 degrees.

• TRANSFERS—open 65 degrees BBDC; close 65 degrees ABDC; duration 130 degrees.


C5:

• INDUCTION—open 45 degrees ABDC (above bottom dead center); close 62 degrees ATDC (at top dead center); duration 197 degrees.

• EXHAUST—open 92 degrees BBDC (below bottom dead center); close 92 degrees ABDC; duration 182 degrees.

• TRANSFERS—open 65 degrees BBDC; close 65 degrees ABDC; duration 130 degrees

it seems like I could either widen the opening in the crank or widen the case to achieve different induction timings, which is the right way, the HPI is pretty restricted where it goes into the crank opening.

dont cut the crank up 2 much, uther wize it will bust.......
people have busted cranks cuz they modded em 2 much..;)

You should grind on the crank over the case b/c you don't want to risk losing the seal around the crank in that area. When the cranks broke by the induction port I think it was mainly due to the edge of the hole being too square or sharp edged, so all the stress was located in the weakest spot where if the corner was radiused more would be stronger. Also making sure the intake ports on sleev all open at same time instead of one side sooner than other will make more power then also making sure all the ports open straight or square instead of from one end to the other or however. On .21's though you have to be careful with if the ports open square or tapered from one side or center out b/c the ports are bigger than on .12's and the piston can catch on them, especially exhaust port.

hey folks haven't heard from anybody in a while...got a ? though

Just want to know.....has anybody tried using large duration numbers for induction on a .12 engine..like 220, 230, 240. If so did you like the results?

My max on a .12 is 218 degrees. It's a monster, but thirsty

Hmm....I was wondering I got a NS12 5 port I was thinking of trying 220 and boring the crank out a little more. Not really worried about fuel economy because I will only mess around on the track with it. An X12 (RB or Mugen) will be my legal race engine.

Stefan care to share any open or closing #'s :sneaky:

Hey all iv never modded any engines in my life and was just wondering What you are talking about when you say 200,220,230 degrees. how are you working out the Degrees and the degrees of What?

Can you plz let me know. Becasue i got no idea.

Thanks:)

When modifying the engines we bolt a 360deg protractor onto the engine to get a reference. The figures stated are numbers relating to when the ports open and close and how long they stay open as in regards to a full turn of the protractor from the piston being at either the Top Dead Center or Bottom Dead Center.

here's a very good guide on the basics of timing.

http://www.rcnitro.com/rn/articles/engine_timing.asp