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Old 04-07-2004, 10:06 PM   #7936
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Quote:
Originally posted by InitialD
Yup, that is if you have a failsafe... I sometimes inadvertantly do it myself without realising but with PCM failsafe, it can be dangerous too when the car stops dead in the middle or at the end of a straight.
I have PCM and it seems to brake when batt runs low.
You dont really need a PCM to do this. When the batt runs low, you can feel it, as the car drives funny.
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Old 04-07-2004, 10:19 PM   #7937
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[QUOTE]Originally posted by rodrigo1508
[B]Hi I would want your opinion on this post at rcu

I think he does not make any really false statments. Break-in IS about heat cycling. Although I usually never allow my engines to go to WOT in the first couple of tanks, I don't idle them either. Bring them up to temp, let it run for a while then cool down (with piston at BDC). Way to go. I hear about a lot or airplane guys that break-in their engines using the WOT method, and controlling rpm with the HSN, but I always felt more cofortable using a slightly rich setting and staying at, say 1/2 throttle and checking the temps at minimum 200-220 degrees. Simply letting an engine idle through a couple of tanks will do nothing but harming it (for the reasons described in the post).
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Old 04-08-2004, 01:41 AM   #7938
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Thanks "B". I think I'll just run down the batts like you said. I've spent alot of money this past month getting back into on-road racing. Between the two 710 kits, NS12S3, pipe, servo's, batteries, Ultimate HUDY Setup System, body and other misc. items, I've pretty much broken the bank! Plus I still have to order my 20 sets of tires and a few other goodies from RC-Mushroom once they get the FAST TIRES back in stock. SO I better save my money for something more useful. Besides, like you said, if the battery craps out I have two spare battery packs!
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Old 04-08-2004, 01:56 AM   #7939
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Quote:
Originally posted by SupermaxxRich
Plus I still have to order my 20 sets of tires and a few other goodies from RC-Mushroom once they get the FAST TIRES back in stock.
Hope you got the dish rims versions of the FAST tires.
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Old 04-08-2004, 02:07 AM   #7940
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Didn't know there was two different knids "D"???? Why "DISH RIMS"? Do you know of any other places that sell good foams at a reasonable price? RC_Mushroom won't have stock for another 3 weeks and from what your saying they may not even be right!
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Old 04-08-2004, 02:13 AM   #7941
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The other type that FAST has are the ones for the Mugen. The rear wheels are offset. You can still use them on the 710 but you need to reset the rear trackwidth. If not, you get wider than 200 mm.

Besides, a lot of people I know prefer dish wheels. They last longer and don't bend or break easily upon impact.

You could also try Power tires. They are the same but they do not come with dished rims.
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Old 04-08-2004, 02:38 AM   #7942
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Quote:
Originally posted by rodrigo1508
Hi I would want your opinion on this post at rcu

Rody Roem -RB Engines- runs-in his teams engines at WOT from the first tank on a bench with propeller. He also covers the head so the engine will pick up temperature.

The thread were this is discussed is here:

http://rbproducts.com/rbww/ubb/cgi-b...c;f=4;t=000096
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Old 04-08-2004, 02:39 AM   #7943
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I agree with you on almost everything-we have to run in engine on hot side ( 200-230 F), we need to make heat cycles. But I totaly disagree with you about following:
Quote:
Originally posted by rodrigo1508
[B]/The manufactures canít make a piston/sleeve turn over smoothly at room temp, because when the engine runs the sleeve will expand and there will be no seal at operating temp. See how that makes sense?!
[B]
I can make for you any piston material with any expantion rate you want to- it can be tight at cold and loose when it hot or loose at cool and tight at working temperature. It is not question at all to make any expantion rate. There is a lot of issue related together with expantion rate-what is friction rate, what is wear out rate, how stable geometry of piston etc. This is why the most sofisticated studies in Nitro engines were done in last 30 years to find the best piston material and be able to reconfigure it to particular applications.
Very well done engines need just 10 minuts brak in period at 200 F.
I have never run in my stuff more then one tank and I mean it. Even if it is original well known manufacturer ( Novas, Sirio OS etc) if you lap it before inital start will make brake in period much shorter and life of engine much longer.
If I am talking about my own P/S sets or my own engine Palmaris PS12, we create material which dynamicly respond on temperature and it is changing fitting according operating temperature.
BTW, every manufacturer during the process of making piston makes two time stress reliefe process one rght after casting is done and second before final grinding of piston to fit. So heat cycling has nothing to do with stress reliefe. Just while we are heatcycling engine, all moving parts are fitting to each other ( bearings conrod bushings, shaft/crancase joint etc.) better while they are in hot condition (materials theory stadies)
Does it makes sence?
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Last edited by Top Gun 777; 04-08-2004 at 02:45 AM.
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Old 04-08-2004, 05:01 AM   #7944
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Can someone tell me what benefit you get when you make your fuel tube longer? The one that goes from the tank to the exhaust?
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Old 04-08-2004, 07:11 AM   #7945
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Quote:
Can someone tell me what benefit you get when you make your fuel tube longer? The one that goes from the tank to the exhaust?
This is so if you crash of flip over, you have a few extra seconds till the marshal gets your car running. If the line is too short and you flip over, you'll run out of fuel and the car will shut off.


Now, I am not sure about the time that goes from the pipe to the tank. I've seen people make that one longer. can someone tell me why?
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Old 04-08-2004, 07:16 AM   #7946
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Quote:
Originally posted by cyba888
Can someone tell me what benefit you get when you make your fuel tube longer? The one that goes from the tank to the exhaust?
The effects are subtle but tremendous enough to impact your engine's and therefore your car's performance.

I've tried a lot to find more info about it in the past but have always ended up having to experiment each time I change my pipe/engine combo. Its like another black art to me.
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Old 04-08-2004, 07:20 AM   #7947
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Quote:
Originally posted by Top Gun 777
I agree with you on almost everything-we have to run in engine on hot side ( 200-230 F), we need to make heat cycles. But I totaly disagree with you about following:

I can make for you any piston material with any expantion rate you want to- it can be tight at cold and loose when it hot or loose at cool and tight at working temperature. It is not question at all to make any expantion rate. There is a lot of issue related together with expantion rate-what is friction rate, what is wear out rate, how stable geometry of piston etc. This is why the most sofisticated studies in Nitro engines were done in last 30 years to find the best piston material and be able to reconfigure it to particular applications.
Very well done engines need just 10 minuts brak in period at 200 F.
I have never run in my stuff more then one tank and I mean it. Even if it is original well known manufacturer ( Novas, Sirio OS etc) if you lap it before inital start will make brake in period much shorter and life of engine much longer.
If I am talking about my own P/S sets or my own engine Palmaris PS12, we create material which dynamicly respond on temperature and it is changing fitting according operating temperature.
BTW, every manufacturer during the process of making piston makes two time stress reliefe process one rght after casting is done and second before final grinding of piston to fit. So heat cycling has nothing to do with stress reliefe. Just while we are heatcycling engine, all moving parts are fitting to each other ( bearings conrod bushings, shaft/crancase joint etc.) better while they are in hot condition (materials theory stadies)
Does it makes sence?
Sorry ... what do you mean by "you lap it before inital start"?
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Old 04-08-2004, 07:26 AM   #7948
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Quote:
Originally posted by Profoxcg
This is so if you crash of flip over, you have a few extra seconds till the marshal gets your car running. If the line is too short and you flip over, you'll run out of fuel and the car will shut off.


Now, I am not sure about the time that goes from the pipe to the tank. I've seen people make that one longer. can someone tell me why?

I think there is confusion here.
The question was about the length of the pressure line (pipe to tank), not the fuel line (tank to carb).

A longer fuel line (tank to carb) will help a flipped-over car run longer, since there will be more fuel in the line. However, there may be limitations to the length of fuel line you can use (especially at big races) because you are in essence increasing the fueltank capacity above the 75cc limit.

A longer pressure line will help to "soften" the pressure pulses going from the pipe into the tank. This will help to maintain a more even pressure of the fuel system, which makes for smoother operation (especially at idle). Note that this will result in a less-pressurized fuel system, since you are increasing the volume of the "pressure chamber" which results in decreased pressure. It is a trade-off. I have always used a pressure line at least 8~10" long.

Try this... put a really short pressure line between pipe and tank. Run the car, then come in and with the car off the ground blip the throttle... watch the effect on the fuel in the tank. It may "ripple" the fuel because of the high pressure.
Then install a long pressure line and repeat the process. The effect on the fuel will be dramatically less... no "ripples" in the fuel.
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Old 04-08-2004, 07:48 AM   #7949
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Titanium screws

I know some of you use titanium screws on your cars and I have been looking for a place that sells them. So far my search has only come up with complete sets (but none for Serpent). Unfortunately my source for aluminum screws (www.fastener-express.com) doesn't have any titanium.

I know HPI has packages of 5 (for $6!) but I am hesitant since I own Serpents, not Hopeless Parkinglot Invaders. That and I can't stop but think there must be a place where these screws are cheaper... Since I've seen full sets of 130 screws for ~$60

I'm looking for selftapping screws (prefer hex over philips) and an assortment of M3 screws. Is there anyone who can guide me to a good online shop for this? Thanks
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Old 04-08-2004, 07:52 AM   #7950
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Quote:
Originally posted by Sow&Steady
Sorry ... what do you mean by "you lap it before inital start"?
Lapping is were you reduce the overall diameter of the piston to remove some of the pinch at the top of the sleeve. People believe a tighter pinch is better but this is far from correct. All you really want is enough pinch to create the combustion process. Excess pinch actually puts strain on the engine on initial start ups which is why most engines dont last any length of time and also why people reccommend changing the conrod after break in.

If the piston is lapped correctly the engine will last a lot longer and you shouldnt need to change the conrod after break in.
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