oooppppssss
 

Motorman,

I forgot

I currently use RB 1050-7's,

but I will use whatever makes it better.....

Don't change nuthin cept maybe to a 77 odonnel plug. Vegas has wierd air densities from time to time, In fact the air is really dense most of the time. If you experience plug failures from detonation go to a 99 odonnel. but for the time being it looks like you have a good combo.

thanks fo rthe response.....

I'll order some odonnel plugs, but from who????

any recommedations???

Hi Motorman.How do you rectify this condition?
Thanks

Motorman,

I saw that there is 77's but the picture is for a standard plug, is there a 77 turbo plug from O'donnell????:weird:

Motorman,,,,,, I read this And was wondering...

I've been keeping my mouth shut for a long while but I have to say somthing.
TG you need to let go of the marine mentality man. If it works for you great but I know I can make more power than you on 30% at .018 and 40% at .021 with zero detonation at 4.5 mm exhaust height. we do it every day no problems. What you shouldn't be doing is spinning people off towards unrealistic head clerance on their production motors. If its a hand built thats a different story but you do them a disservice by directing then toward toward a global meltdown of their hardware.

If you feel inclined to take .008 thousanths head clerance advice do so at your own risk that is all I have to say.



I have ran My motors ( 12`s ) at .018 With 30%.

I wanted to what you felt about about .015 with 30%
I have fuel made to my spec. with 6% caster & 4% synth.
I have raised the Exguast timing .007 in a way with keeping the 4.5 mm rule in check.
This motor will be a RS- 12 TS1 Turbo with a #5 plug.

Let me know what you think.
I personaly think I am Ok But I have not been in the Motor bus. As long as you . Thanks In advance.

I will say this with reservation, Yes you can go there just watch the temp, it may get real fussy at low altitudes, so it depends on where your located. Also watch out for detonation. I would recommend a cold plug like an odonnel 99 or an MC9 mccoy. In the turbo situation try a 7 and if alls good drop to a 6.

what its going to do for you is add torque you may lose a few rpm on the top. The other way to skin the cat so to speak is to go to 40% and use the cold plugs at .018 this works well in moderate conditions. at low alt or above 80 degree conditions you may need to go .021. Air density,temp and pipe wave strength are the critical factors that will determing the point of detonation at a given trapped compression ratio. It is something you will need to fine tune for wherever you are in the world and the conditions of the moment

I've tried larger combustion chambers with tight head clearances but the squish velocity is just to slow in my opinion to achieve the burn rates in the cylinder I'm looking for.

I'm really big on chamber design,squish velocity, tumble and burn rates in the cylinder. Max power is all about cylinder charge speed, tumble and burn rate at the highest exhaust timing you can get away with without killing low speed torque. Thats the jist in a nutshell.

you'll notice that automotive manufacturers are dragging huge amounts of power out of older engine designs like the pushrod gen 4 small block engines. It has come from 4 things
1 injector targeting
2 port swirl
3 combustion chamber design
4 charge direction at the plug

yes their 4 strokers but those for me are the highest priorities on my list.

Timing IE. the camshaft/valves (crankshaft, port shape)is the easy part.

the oddity on 2 strokes is the tuned pipe, often over looked for the cheap or cool pipe of the week will make or break the performance of the engine.

It is the single most important part of the combination bar none. Throw all that stuff I mentioned above this line away and I can tell you for a fact that the proper pipe will wring out more power as a single item that all the above combined.

wow this reminds me of posts I used to make, Musta had a moment er sumthin.

The more the merrier hopefully !

So how do you choose the correct pipe??

I have an NSR 3 port with 0.014" head clearance running Novarossi no 5 plug on 16% Nitro.

The track is shortish so will need low end power.

There are different makes of pipes but what are the specs that determine which one to choose or do you believe the hype of the people selling them??

Cheers

high altitude
 

hey motorman ,what head clearance and plug would you rec. for
hot weather over 80 degrees and thin air say in vegas running
nova motors at 30 or 40 %. :p
currently at 0.21 and very cold nova plug in la. weather.
thks 4 your support

Motorman,
Thanks for the fast Reply,
I also Believe ALOT in squish. Deck Hight & Compression Ration With related Exguast Hight.
I live in Fl. So I might be on the Ragged edge For my Initial Setup.
Thanks Again.

Mugen
hope it was usefull to you.

Isuzuguy
well actually vegas can be decieving. The last time I was there for the speedline race last year the air density was really high. It was detonation central for us. If your going there I would actually plan to take a two piece pipe setup and step down a plug range or maybe 2 colder if detonation becomes a problem. I would strech the pipe a quarter inch longer than your one piece setup first. The other option is to use an RD one piece pipe and take both length headers we have. start with the short one and go to the long one if detonation rears its ugly head. I pushed three engines to the limit and killed 2 of them and that has not happend to me in a long long time, Broken pistons. Gearing the car to tall can cause detonation too, as can to lean a top end adjustment. I think I would stay at 21 especially on 40 running at sea level or close to, above 80.

How to identify detonation: the plug will be burnt in a way that the plug looks gray and bristly where the wire is left. If this happens take the head off and look for the piston and or head to have a Matte sand blasted look if so the engine is detonation and it will kill itself unless steps to correct the condition are taken immediatly.


Ziggy
I'll make it easy for you
3 choices for your engine
RD one piece 615L version
Nova 625 version
Novamega TPO6

then gear the car to get the torque where you want it. A torque pipe for the sake of torque which can be compensated for with gearing will hurt you. Once you have achieved max torque by gearing the car if you still feel you could give up top end then look for a torquier pipe.
That is the way I would go about it.
RD will be releasing a new pipe I designed very soon (next month) that should jack up torque and horspower beyond the 615 RD pipe. However I still like the 615 alot and consider it one of the best value/performance pipes for the money. Theres a pipe that starts with an O that makes a good paperweight. :)

Motorman,

I also race at high altitude (approx 6400 ft above sea level) using 30% nitro on a RB X-12. May have experienced some detonation, at least by your description of the way the plug looks. What do I need to do to make sure this doesn't happen again? I still have stock head clearance as I have not opened the engine up for myself.

Your probably not actually having detonation but I would pull the head and look if I were you. Your probably having lean plug burnout. It would appear my friend that you are at the other extreme. at that altitude the air is so thin that you could be suffering from to low compression. whats happening is you are having to overlean the engine because of the thin air to make power, because the Dynamic compression is way down. In your case I would go down to .014 head clearence and go to a hot plug and see if that does not help. I would use 40% fuel if I was in that condition.

There is a track in Mexico that when people go there you typically need a completly different head button to correct this condition. I cant remember if thats pegaso or not. I personally have not been there but I remember Ron Paris talking about it.

Motorman what do you think an RD NTC3 turbo pipe would be like on an STS D5 turbo engine ? The track I'll be racing on is fairly short (100' straight) with a tight infield....

RD Logics turbo NTC3 pipe...

http://members.rogers.com/sgreenly/photos/rdturbo.jpg


AE dual chamber NTC3 pipe...was considering one of these too ?? I'm soo confused :confused:

http://members.rogers.com/sgreenly/photos/aedual.jpg

on a track that short run an associated pipe. it will make more torque.(it has more flatband length in front of the weld, about 3/4 of an inch) your not going to get into the revs much. The Rd pipe is more suited for tracks between 160 and 250 ft

Hey Dennis,

i just arrived in Ft Myers today and saw the track in real live.

Now I know why everybody calls it a beatch :D

Man that's tight, it looks soo much bigger on the pics.

I wouldn't wanna drive an 8th scale there.

Whish me luck...:weird:

yea brother
and they've toned it down I hear from when I was there in 2002. That S in the front was a really bad scene. you have to be in against the wall and full throttle through there to be fast just kicking the tail out as you pass the S into the sweeper. If you hit the S your an airplane, your car will be broken guranteed. My friend Brent Gottfried used to say if you wanna be fast you gotta drop your sack and pull the hammer back. :)

Them Iron boards win every time! Have a good race wish you the best.

Motorman,

I know you probably hate questions like this (or maybe Boomer was messing with ya), but can you give us a answer?

I sent him a PM. I'll see if I can dig up the text from it.

Motorman wrote on 11-22-2003 06:51 PM:
Ah here it is.

General novarossi numbers, values are in thousanths not MM
.008 head clearance is built in with no shims. added recommendations include this value. Take them as they are posted

20% you can get away with .014 with a 77 plug

MT/12 30% fuel use .018 shim which is stock with an odonnel 77 plug this will yeild good results.

Changes from baseline
add.004 will add top end and lower bottom end
subtract .004 will add low end and detract top end

Plug change from 77
Hotter will advance timing and add top end
Colder will retard timing and add torque

40% use .018 +.003/4 with an odonnel 99 plug which is colder

the later will produce the most power

Thanks Motorman.

All this talk about shims got me thinking about mine. I bought a used NS12 S3 off Ebay. It runs and sounds great but I haven't had it on the track. Anyhow, it has two .012" shims under the head (for a total of .024"). I very carefully used the solder trick to fine my piston/head clearance. I came up with .035"

This sounds like alot more clearance than what people here are saying they have :confused:

But my engine sounds good, it idles good, and it looked wickedly fast on a empty parking. I used 20% nitro and what looks like a NovaRossi 6 glow plow (engine came with it).

I would reshim it back down to what has been recommended, you will see a power gain. It didn't come from the factory with both shims. The is .008 built in with no shims.

This is a great thread...great info from everyone. After reading through I realized that I need digital calipers badly. In the meantime...Motorman, you say stock is .18. That's the button with just the silver (.3mm shim) right?

REX P5 shim tuning
 

Motorman,I was wondering if you have any experience with this engine and what would be a good starting point for 1000 foot elevation ,high humidity,offroad. It currently has .21 head clearance and running 30% fuel.also do you have any reccomendations for break in processes as the novarossi manual is rather vague.....

In case Dennis won't have an answer, you'll find lots of info here:

http://www.rc-racing.com/cgi-bin/pw/...howforgotten=2

Motorman, I am new to this site and have learned a lot from this thread but I do have one question. I have an RB X12 5 port turbo in my Serpent Impulse Pro and I want to change from 20% to 30% nitro. It has the stock shim (approx. .015", I don't have a digital micrometer) and I read elswhere that you are supposed to add a .01mm (?) shim if you want to run 30%. Based upon the info here that would seem incorrect. Do you agree? I would really like to know what you think. I live in So. Fla (hot, humid and +10' above sea level). I would also like a glow plug recommendation please. I have an MT-12 I am putting in my truck and the info you gave on that was perfect.

Thanks,
jag

SHIMING A .21 ENGINE
 

MOTORMAN or anybody with experience, can you post the basic guidelines for correctly shiming a .21 engine???

Lets say an Off-Road Nova .21 based engine using 20% Nitro at sea level, what would be the ideal total chamber?? and the recommended Glow Plug??
Air temps are between 15 and 21° C and humidity around 75% to 85%.
Thanks
AFM

Re: SHIMING A .21 ENGINE
 

Anybody care to comment on above
Thanks
AFM

I am planning to get a Novarossi NSR12S5 or NS15S5 engine and they both come with 0.3mm head shim (correct me if i am wrong)
I will be running 20% fuel. In that case, Do i need to add 0.1mm head shim to get proper compression?

Thanks.

I just got one and the manual says 0.3mm is perfect for 0-20% nitro and 0.4mm for 20-30% so should be ok with 0.3mm

Can anyone here tell me where I'd find a degree/timing wheel small enough to use on a .21? My best friend has been building some BALLISTIC engines by "making adjustments" to the port timing on his sleeves with a Dremel. I'd like to get him a timing wheel for Christmas.

quick question:

if engine is losing compression, will removing shims helps to boost compression? :weird:

Speed - you can buy yourself 2 protractors or print one from http://www.ossmann.com/protractor/

Keavze it can help but not for long.
Your options are to have the sleeve pinched or buy a piston/sleave set or just get another motor.

For 16% we found .35mm clearance to be ideal and .4/45mm gave a tad more rpm but lacked bottom end.

what do u mean by 'pinching' the sleeve? :confused:

Pinching is expanding the piston or making the sleeve smaller for a tighter fit.

ok but how do i do that? :weird:

Check with your local racers, usually there is one or two guys that pinch sleeves. Even try the local hobby shop.

Basically its squeezing the sleeve just a bit to give the piston a better fit.
It does give just that little bit more life out of your engine and chanmging the rod would be recommended too.