hey Engine Builders!

[CySlyde]

I was talking to Dave about how he modified the engine to his sons nitro hammer by opening up the exhaust port, but before i ruin my engine i want to make sure i'm removing the right part... attached is a crummy illistration of my exhaust port, i think the area needed to be removed is the red area. am i correct? while i am at it is there any other good/cheap and easy mods that i can do?

View attachment 883

 

[GTR]

HI Cy

Mods to the exhaust alone aren't a particulalry good idea. They usuall require balancing up with intake port or crankshaft port changes. Without using a tuned pipe a lot of the increased exhaust area provides little benefit. Difficult to tell exactly what you mean by your drawing and I'm not familiar with the engine in these. We have some really knowledgable people on this board who could probably assist if you can't resist the urge to take to it with a Dremel.

GT :

 

[cy]

Yeah i am going to get a tuned pipe... i was reading on another website on porting, i think i got a general idea, but i think i still need to pull the motor apart first to studdy it.

 

[rhomodel]

Usually when you open up the exhaust they mean making it wider at bboth sides and remove material at the top side, this will allow you engine to rev higher, if you take off to much you have a 50000 rp motor under no load an an engine that will stall when put in water with any prop. You drawing is not good, the black spot should be in the middle down .

Sorry, Julius

 

[Slideblues]

I think Cy's engine might have ports like this OS:

 

[GTR]

Hi Cy

If your engine looks like the OS be careful when trying to widen the port in the case. If you pull it apart you will discover a tranfer port there as OS have rotated the liner through 30-45deg(can't remember actual shift) Their logic being the main transfer is better lined up with the intake passage in the crank.

If you want to widen the port and raise it do so very carefully and only small bits at a time. You need a degree wheel so that you can actually measure the changes you're making. A little done well is a whole lot better than a lot done badly.

Have fun cautiously - this is how we learn what we can improve as production engines are always a compromise.

Oh and you can try boring out the carby a little as well.

GT

 

[CySlyde]

yeah that os looks alot like the one i got.... sorry i don't have a pic.... thanx for the tips gtr... thas why i am asking first

 

[nitrotoys]

Hey Cy,

I hate to say this, But i will anyways.

You NEED to get that boat RUNNING RIGHT FIRST, and Learn to TUNE IT, BEFORE YOU MAKE ANY MODS.

When you mod a motor, makes it harder to tune (at times) Some minor mods work, but normally it has a harder needle settings.

I wouldnt go over board on porting. as if you take it to far it tends to LOOSE power. or if dont wrong.

Beleive me, Im Sure a few have messed up a sleeve/piston doing there "first" Mods.

Now if your going to get into it.

Skirting the piston some helps.

if you have a CROME CYL, DO NOT, DO NOT TOUCH IT WITH THE DREMEL BIT. It will chip the crome, and there went your sleeve. altho 800 grit sandpaper does take the edge off of it. ;D was told that by someone that made the same mistake.

And if the bottom of your sleeve is squared on bottom, taper it on a 45 degree angle, will get better flo.

can open up the inside of crank, and timing inside can be adjusted, by the opening, course the more power and rpms you get, the less torque.

So you gain some to a point, but loose some.

work on your tuning and getting that to run, before you mod.

trust me, I KNOW, and IM sure alot of others know that as well.

NT

 

[Slideblues]

Cy, matching the ports is a good first mod, If there is sleeve showing inside the port like on the pic of the OS, Just take a scribe and mark it where it will match the port on the case, As NT said go slow take your time if its chromed, little bigger carb and pipe, and run it, go from there. Just remember a little can make a BIG difference, dont do to much too quick.

Gene ;D

 

[TimD]

Ok guys,

Had to jump in and make a few comments / suggestions.

Cy - you are obviously new to playing around with modifying a motor so I would suggest you don't even consider touching the ports on the liner at all! Especially if it has an ABN or Nickel plated brass liner with an aluminium piston.

What I would suggest you try 1st is setting the head clearance down to around 8 thou. This may require you removing head shims or having the head machined.

This should give you some increase in performance.

Also, smaller engines respond very well to having the induction port in the crankshaft opened up too 215 - 220 degees total open. You can grind the crank with a stone bit in the dremel as they are made from steel.

If you have any questions, post them here so that other people can learn too....

Tim.

 

[CySlyde]

NT - funny thing is that saturday was the most problems i have ever had keeping my boat running. usually i just pull the starter and away it goes ;D ben happy with that.

Tim - yep... this is only the second nitro motor i ever had, the last one i always had someone else who tinkered with it (was teaching me how to fly heli's). it has been fun getting everything to go right, but really hasn't been that hard, just followed the book that came with it (shh do'nt tell my mom i followed directions ;D). I do however know the basics (i believe) just from growing up in my dads engine shop... i know there are a lot of differences between a regular car/boat engine and the ones we run, but i think that what i have learned about those will help out.

I think my first step will to be investing in a new set of dremel bits. after that i will get some pics of what i plan to do out before i actually do it... that way i can get your guy's advice on weather or not I am doing it correctly.

-=Cy

 

[CySlyde]

btw i was browsing and saw there was an aluminum cooling head available for my motor can i expect any performance gains ou of just the head or is it a waste of money.

 

[TimD]

btw i was browsing and saw there was an aluminum cooling head available for my motor can i expect any performance gains ou of just the head or is it a waste of money.

Does the motor get hot and fade while running with a correct needle setting? if not no need for a different head unless the CR is different.

 

[TimD]

I think my first step will to be investing in a new set of dremel bits. after that i will get some pics of what i plan to do out before i actually do it... that way i can get your guy's advice on weather or not I am doing it correctly.

-=Cy

No worries - I'd suggest you forget touching the liner to start with. You will need to measure the ports anyway to find out when they are closing first. No point attacking it with a dremel and possibly ruining the liner if the numbers were OK to start with.

 

[Dale]

Cy May be you miss undered stood what i did to my sons boat, i opened up the header pipe to match the motor exhaust port, i did nothing to the motor exhaust. or sleeve. What i did is a simple trick to improve the flow out of the motor. On that particular motor the exhaust on the motor was huge compared to the little hole in the header pipe so i matched them up.you seen how well that boat ran,and all my other boats i think i know what im doing. What i want to know is what hobby store let you buy the boat you have now. I know you might be on a budget, but theres alot of boats out there that would give you more enjoyment.Do yourself a favor and build a radio box to try to keep your radio gear dry. Im not trying to be snotty but i hate when a hobby store sells an item just to make a buck when with a little more cash you could have maybe got something better.Iv also done motor mods to all my outboards, and have found tuneing them no different than stock tunning.iv been running boats for 4 years and im by far no expert,and iv made mistakes the first year or two but luckely iv had my friend Bill ( the guy with the gas apatchet boat ) help me along the way he's the real boat expert here in Toledo. If you need any help with your boat or future boats i'll be glad to help buy a tunnel you'll love it. HTB Dude the only way to go.

 

[Dale]

I know many of you may disagree with this statment, but remember i did not say this, this is what i was told buy jim erwin he did different work on sleeves for K&B for years and found no difference between mod and stock in dyno testing . All i no is everthing he's told me to do on my motors has worked just fine. i do no grinding on my sleeves, only the crank, and i play with different shims,and make sure the motor spins freely.

 

[CySlyde]

ic.. yep i think i did miss understand you dale... either way i may try some grinding, just to see if it works. I actually got the boat online. I didn't want something too expensive as i was afraid of totally kiling it straight outta the box. and i wanted something ready to run, and not to fussy and not needing a ton of support equipment (this is why i dropped the electric idea. the reviews i read seemed that this was a good boat that was not as expensive and manufacturer specific as the traxxas which i got sick of being on backorder at the lhs. plus i was getting ansy to get out and do something different that would get my mind off the things i was trying to forget. so far i have been happy, maybe i just don't know any better, just now i am thinking i got some time driving it, and in my usual spirit it's time to test it's limits.

plans for this winter are a better radio box, prolly a new radio, and a tuned pipe for shure and your right i am ready for something a little bigger/better so to speak. but i am waiting on the tunnels yet. i like them, but i still think i would be happier with a hydro.

-happines is key to living a young life - grampa Hepp

 

[dale]

Thats for sure make yourself happy first, just do some research on what ever you buy. Im looking for a gas boat for next year, just can't make up my mind :-

 

[CySlyde]

yeah umm... something like juice's cat would be realy nice... just don't think the budget would like it as much is i would