calvino

I know some guy skeep secrets () but how does one find the timing and then go on to moddify it on your engine [8D] In this case I have a Mach 427 and an LRP 28 that I want to change the timing on but I am not sure how to go about doing that. Anyone willing to share, last thing I want to do is take a nice engien and trash it

authorjim1

I am anxious to hear this answer. I am not being facetious but I have never even heard of timing for these types of engines. The only thing I can think of is modifying the intake and exhaust ports to change the airflow characteristics and I quess by doing that you would also be changing when the airflow enters and leaves the engines. I hope the guy from AB mods chimes in on this, because he would know. One thing I have heard that is unless you really know what you are doing based on alot of testing and experimentation you can really screw things up by messing with the ports.

Come on guys chime in and lets talk about this.

Jim

bigdogkanicsar

well, if the engine you already have is full of torque and power, then this type of mod is probably not a good idea. as for the lower end engines, timing changes( i say changes because once you've done this it cannot be reversed ) are done by altering the exhaust port and the intake window on the crank shaft. you will need a dremel tool and some carbide and high speed steel cutting bits. i will post a couple links on porting. if you don't have the experience with dremel precise cutting it is best left to a mod shop.

http://www.rctech.net/forum/nitro-ro...ro-engine.html

this is a port and polish how to.

http://slappytees.com/images/savage/...I%20Nitro1.pdf

this one is how to make the HPI S25 a real performer. the last number after nitro in the link, change it to 2, 3, or 4 to veiw all pages.

VooDooModified

Why do you want to change the timingm what performance aspect are you wanting to gain? Torque, RPM's...?

calvino

Generally "both" but maybe more RPM's from the engine From what I remember the LRP had good torque but I found I wanted a few more revs if possible

oslo

You'll need to change timing to the crank and/or intake and exhaust ports to get more power and rpm out of the engine.
However, the lrp .28 is quite aggressivly timed from the factory. Durations: Crank 214 degrees,(opens 22 degrees ABDC and closes56 degrees ATDC) intake 130 degrees and exhaust 174 degrees.

Flow mods does little to the engines power output

The power is in the timing...

VooDooModified

send it to me....I'll make it faster

Colt4g63

You can use something as simple as a timing wheel to measure port timing or calipers, depth gauges etc to measure port height and use a timing software to put the #s in and keep notes etc.

As far as knowing where to move and what ports to move the timing on is the trick... This takes many years of experience and R&D to do it properly and get the end goal that you want out of the engine.

calvino

Thanks Adam. I decided to just "do the flow mods" on the engine and thats it. I think it is best to leave the timing stuff to the pros I have gotten about 8 gallons out of it and I think I want quite a few more, instead of risking it all.

SAVAGEJIM

The easiest way to determine the timing profile is to get a degree wheel and measure each specific port duration.

Or just like what Adam said, you can measure how far down the piston is with a caliper and then calculate the duration from that height measurement.
The software he mentioned is really nice because it does all the calculations for you. This is great because it totally eliminates all the trig work that you would otherwise have to do to calculate the sleeve port durations
These are for the sleeve ports now, which are relatively straight forward.

The induction port on the crank shaft is not as easy; it does take a bit more measuring and calculating before you arrive at the duration for this specific port.
I wrote this thread several years back tackling this port duration calculation and also calculating how far you need to cut to open up this port.
http://www.rcuniverse.com/forum/m_59..._1/key_/tm.htm

Making sense of when this induction port opens in relation to the sleeve ports requires plotting your port durations on a timing profile map.
And this is where the software that Adam describes makes it beautiful; provided your measurements are accurate, the software will do this duration plotting for you and give you a concise timing profile map.

And yes, as far as modding, it does take considerable experience to know how to make these port durations work in unison to give you an effective power increase.

Over_revO

Thats not true, it depend on the existing timing, compression and design. The power output also have nothing to do with how far you can go, no offense...

ABmods squeezed 1/2hp more out of an OS.28XZ as a perfect example. (1.97hp stock, 2.51hp drag mod)



For the timing, the degree wheel is a good way to understand how it work, but the software is a lot easier and precise lol
Like Adam said, if you want to learn, you will have to spend time and money to test , test and test.

Took me a while to learn, and some $$, and some help from a good friend who is pretty good i have to say...



If you are really looking to learn it, take your time, do small change and test, 0.2mm can do wonder or disaster.

Good luck!

bigdogkanicsar

none taken , i was just basicly sayin' the average joe (not to say anyone is the average joe) shouldn't attempt these kind of mods without prior knowledge of how tweeked the engine is from the factory, more or less if you go too far you might turn it in to a paper weight. i've done mods of this nature to four of my engines and no paper weights yet. knock on wood. however i personally wouldn't try it on a 45,000 rpm, 3+hp engine either. ya know what i mean. on the other hand i do see what you're sayin' as well.

rcnitrohead

Damn I didn't know there was a nitro car engine capable of 3hp and 45,000 in the same package.. Things sure have changed in the last year [&:]

bigdogkanicsar

well my mistake 2.7hp with practical 45,000rpm or that's what they claim
check it out

http://www3.towerhobbies.com/cgi-bin...?&I=LXXYF6&P=0

rcnitrohead

The bold is where you fail. I'd like to claim my Picco .28 puts out 4.5hp at 50k RPM.

bigdogkanicsar

you know what, i didn't FAIL .the link i put was from tower so it isn't my failure. maybe you're the one who FAILED to watch the video from o.s. directly under the picture on tower. i remeber some of your posts on other threads. you're the one who likes to get all cocky like everyone is out to get you. grow up ,bud.

rcnitrohead

What does a video prove? The same thing as you claiming that an RB Supercharger works right? You like talking but can't back **** up with facts.. The average joe R/C guy knows that numbers advertised for nitro engines are the same numbers that are pulled out of someone's ass. Cocky? Really? My advice for that guy was spot on IMO, I gave him exactly what he needed. If anyone needs growing up, its you man.. Go strap on your RB supercharger and make some boost while your at it...

bigdogkanicsar

see ,you're funny too. i give you the link to where o.s. runs the info on the engine and you still waana be 10ft and bullet proof( which is pretty easy to do over the net) but you are the uneducated one that can't read what people write. I SAID THEY CLAIM. not i claim. go back to school. maybe you and that dude ought to shack up together. maybe O.S. does embelish a little along with every other manufacturer. but at least i posted the stats according to O.S. and tower. where are your FACTS homey?

just so we are clear i never said the supercharger was a giant boost in power, i said it makes up the difference for it's weight + a little more. and that's from the one i had. i can't speak for other people. you just like the other guy need to learn to read.

rcnitrohead

I read what you wrote accurately.. You said a supercharger WILL produce gains.. Previous discussions (and I could dig through about a hundred threads) which included those that are extremely knowledgeable on the subject deemed it impossible to work on surface specific nitro engines.

As for the O.S., I did read accurately as well, and here is what I go by:

Adam's dyno sheets..

Xtreme RC's engine database

Which show extremely different results relative to manufacturer claims.

Colt4g63

XRC and I use the same dyno. The X-Dyno which has become standard in the industry of HP ratings for engines. Its in SAE correction factor.. Has a weather station etc. Its the REAL DEAL.

bigdogkanicsar

i'm not disagreeing with rcnitrohead it's just this guy has no tact. i use an example of why the average guy shouldn't do engine mods on his own and this guy tries to twist junk around to stir the crap pot and get people goin' cuz he's got no life. i never stated that it was a fact, however i did state that it was what they claimed .i have noticed that when people have a computer between them that think it's funny to run their mouth. i get it ,it's easy to act tough when they are not face to face and the realizm of losing teeth isn't present. the manufacturers do imbelish as i am aware.

rcnitrohead

^ Hey, just doing the exact same thing you did in the other thread... LOL

Tact or not, I'm here with facts.. You can go ahead and keep whining about etiquette. No life right? So one can assume there everyone on RCU is a loser with no life right? Cause this thread and 2 on the HPI forums are the only ones I've participated in some time.. If you think I'm trying to act like a tough guy, you must be more retarded than I thought. I know exactly how and when to act in a certain demeanor, I've done more for my community as well as the local R/C community here than you could ever accomplish in your mom's basement. This is done, all the info was clarified, we've had our pissing match, the popcorn is eaten.. Good day sir.

bigdogkanicsar

demeanor?lol. what's even funnier is i haven't seen my mom's basement since 1978 and i've been playin with rc junk since before computers hit the mainstream in the 80's. helping the bum on the corner get some beer is not helpin' the community, it's contaminating it.

the only losers on here are the one's that have no clue what a GOOD demeanor is.

rcnitrohead

I know when something is finished.. You apparently dont. Sad to see that if you really aren't 12 years old, you continue to argue like a child.. And if you call being a hospital volunteer and an auxiliary police officer giving alcohol to bums, then you have your priorities ****ed up. Good to know that our hobby is junk to you, I don't even know why your here. Good day.

Go ahead and have the last word, I could care less.

I also apologize to calvino for letting this turn into a pissing match, sorry for adding fuel to the fire man.

bigdogkanicsar

the one part i do agree with is that very last sentence. hey calvino, we do appologize!