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Old 11-03-2002, 09:39 PM   #1
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Smile Stop me before its too late...

Looking for info about a "Port & Polish" job on my GS.15R engine. Thinking of opening up the port holes in the cylinder liner and crankshaft to get more output from the engine. A little more than 1/2 gallon on the engine so far.

The claimed HP is only around 0.75. As you know some of the other .15 engines have over 1.2HP. Most have anywhere between 4 and 8 ports. The Kyosho has only 2.

Anyone who has successfully (or unsuccessfully) done this to their engine please respond with a posted reply or PM.

Stop me before its too late...
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Old 11-04-2002, 12:13 AM   #2
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Default re port job

1) where did u get the output figure? I reckon youll find it closer to 0.6hp!

2) dremel at own risk! all I can suggest is find pictures of an engine with a similar port setup as standard and try to follow it.

The gs15 isnt a bad standard type of engine and get going ok when they're tuned right, but the question is why do you want to port it. Are you racing? Are you a power hungry freak like the rest of us?
Before you proceed any further are you prepared to replace the engine when you destroy it and you probably will!

The engine is a 3 + 1 Exhaust port.
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Old 11-04-2002, 12:25 AM   #3
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A little bit can mean a lot. If you don't know what you're doing and why, it could give you a lot of headaches. I might suggest that you get a new engine before you use your dremel. To get better at this you need plenty of practice, but I don't do it much because I don't have enough money to get engines to practice on. If you are doing this as a shortcut to getting a new, more powerful engine, then I suggest you do a little, not a lot (one can get carried away doing this stuff) You don't hear about too many two port engines, especially if a company is selling nowadays, So I think it has to be a three port with an exhaust port.
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Old 11-04-2002, 11:42 AM   #4
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Yes, I am porting it because I AM A POWER HUNGRY FREEK!!

The car (actually a truck) has a 2-speed with the tallest gear ratio avaliable. And yet it is not fast enough. It may turn out that nothing is "fast enough" but I do have a new Hot Bodies HB.18 engine still in the box.

I figure I can change the ( you are correct ) 0.6HP GS.15R out to the new HB.18 with 1.3HP. That should get the front wheels up.

No intention of ruining the GS.15R but if I could pick it up a bit I would be happier.
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Old 11-04-2002, 01:33 PM   #5
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Default dremel

then dremel away!

ps, when you remove the header pipe have a look at the exhaust port in relation to the exhaust casting in the block, the theory is that the less obstructions, the better.
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Old 11-04-2002, 11:25 PM   #6
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If you're looking for power, may I ask why you haven't gone toward a Rossi or RB Concepts motor? Their .12's are rated at twice your original motor's HP.

Aside from opening up my exaust header and trimming a little bit off the end (for more rpms) I am very wary of taking a dremel to a $150 motor. There are other ways, and there are people who do mods and really know how they are done.

Anyway
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Old 11-04-2002, 11:57 PM   #7
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thats true....but there will allways be an adventurous part of us that has to give it a go.......I believe it known as the mad scientist gene

muhahahahahaah

gt

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Old 11-05-2002, 02:29 AM   #8
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Also he has a backup engine in case things don't work out. But I agree that a novarossi or any competition .12 would be much stronger than either motor no matter what.

Pay attention to tuning, your engine is going to act differently to different needle settings now. Your going to have less of a margin of error, and overall your going to have to richen your needle settings because more fuel is going to be going through the engine.
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Old 11-05-2002, 08:00 PM   #9
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I was told if i was to port the GS15-r that to only port the exhaust port and it will give you more power.
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Old 11-06-2002, 01:50 AM   #10
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There are many facets to porting an engine, and that is why most people shouldn't port their latest and greatest engines. The duration of the exhaust port being open, the intake timing, design of the boost ports, and a buch of other stuff I have no real clue about. They all affect an engine big time. Fussing with these can be like doing the Willam Tell while blind-folded if you're not sure what your doing things for. That is why I prefer to keep porting to the pros.
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Old 11-06-2002, 04:04 AM   #11
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yep....I agree.........but nothing can supress the mad scientist gene that tells us that companies like kyosho dont know jack regardless of the fact that they spend millions on r&d every year.

gt

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Old 11-06-2002, 11:39 AM   #12
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Default Porting

Don't open up anything on your engine with a Dremel. You will change the timing and can destroy the powerband. Just smooth up any rough edges in the crankcase and maybe add a tulip cut at the back of the crankshaft. You will be amazed at how much extra power you will gain. There are ways to angle the outside edges of the ports to promote fuel flow. But it is very important where and how much to angle. You can cause more damage than good.

Try 30% Nitro instead.
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Old 11-07-2002, 01:26 AM   #13
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Popsracer, I agree with everything you say except about the tulip cut in the crank. this could be dangerous because it could offset the effect of the counterweight lobe on the crank and easily create an unbalanced crankshaft. Take off the lead weights that balance your tires, then imagine that in the engine spinning at 36,000 rpm. That rpm most likely decrease at the hands of an experienced tuner. Porting and polishing an engine is difficult and involves mainly a bunch of misunderstood, or totally unknown, facets of engine function. If you had one of those engine timing wheels, I still would not suggest you do much to the ports on the engine. Most small block engines have short timing spans compared to big blocks and modified engines,so you could enlarge the ports a little , and possibly not harm much, but don't expect much if you're just doing it to see what happens.

Also your fuel effieciency will suck if you start hacking all of the ports.
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Old 11-07-2002, 08:28 PM   #14
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Default Porting & polishing

I have "Turbo" cut the cranks on a few of my engines with some improvement in mid to upper rpm power. I really didn't see any more vibration in the engines.
Also, I did this to "spare" Sport engines. I don't have the courage to touch any of my race engines with a dremel.
What really makes a tremendous difference, is to clean up any casting marks inside of the crankcase leading up to the ports in the sleeve. This will not effect timing and usually improves fuel mileage with a noticeable increase in usable power.
Going from 20% to 30% nitro fuel also makes a big difference in power, but with a loss in fuel mileage.

Last edited by popsracer; 11-07-2002 at 08:32 PM.
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Old 11-08-2002, 02:10 AM   #15
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The tulip cut, as I understand it is not truly done to increase power, however, it is made to make the fuel entry to cause 'turbulence', within the crankcase. The movement within the crankcase is supposed to keep the fuel mixture 'atomized' which would create more a more efficient engine b/c less raw, un-atomized (nice made-up word ) fuel would pass through the chamber as unburnt fuel. Also, since your engine is burning fuel more efficiently, this makes the engine run slightly richer, and to counteract that, you need to lean out the engine. This will raise the temperature of the engine. But as you said it will increase power, but it is almost an after-effect due to your need to adjust the needle settings.

If you change your fuel nitro percentage to be higher, say 30%, then your engine will definitely be faster. However, the side effect this would be that your temperatures may seem low, and you will have more fuel visible smoke coming out of the pipe, you will actually need to richen your carb settings. Totally opposite of some of our most basic tuning techniques. If you don't your car will become too lean by the end of five minutes and you'll be wonderingwhy your engine shutoff.
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