1QwkSport2.5r

Can anyone tell me what is the most ideal port timing for an all around strong car engine would be? I'm referring mainly to exhaust timing, but transfer, boost, and crank inlet timing is good to know as well. I've degreed several engines and I've seen these numbers jump all over the place depending on the engine. The stout torque monsters seem to have lower exhaust timing, in the realm of 140-150° with a short blowdown of 10-12°, whereas the higher rpm screamers are up around 160-180° with blowdown timing around 17-19°. blowdown timing. I'm entertaining the idea of finding some better pipes to better suit some of my engines than what I've been using. I'd like to better match the pipe to the engine.. Do any good pipe manufacturers publish any sort of information like the effective RPM range of the pipe (and not just low-mid rpm or mid-high rpm. I'm talking numbers..).


Anyone want to share?

nitroexpress

That would be a no.

llkoolskillet

Im going to have to agree, Pro Modders are not going to give out this kind of info, it would be like giving there work away for free

As for the best pipe... Have you tried an ERCM pipe? They make the most power thru out the entire power band, they dont really focus on one part of it. You can fine tune the header for more top end or low end.

1QwkSport2.5r

I dont care to know what "pro modders" adjust the timing TO. I am asking what is IDEAL. Ballpark range is fine even.
No, for the same reason I haven't tried some other popular pipes.. The descriptions of so many pipes are so vague and general. 1 pipe = perfect fit for every engine from .09 to .20? Not likely. I guess a full-wave pipe probably is the best way to go with a number of headers to adjust for various gear ratios though these make the engine "peaky" and sometimes have midrange problems. Helmholz resonators work in a narrow RPM range depending on volume and length of the pipe but dont hinder the midrange as much.

I may regret posing these questions... But maybe some intelligent conversation will come of it...

Anthoop

Pick and chooe where to reply is my advice.

There are no magic numbers that will apply to all engines...not even engines of the same CC. Duration can only tell part of the story....the port may be really small but open a long time...or...
There will only ever be ranges of ideal figures and it seems you already realise that?

savagecommander

Angle, area, and duration all come into play. jennings and blair are two names that come to mind.

llkoolskillet

If you havent tired any of the popular pipes, then which pipes have you tried?

Also what is your goal for this motor you speak of, and what brand, as many onroad motors have different timing in stock trim?

Anthoop

You failed to mention the most important factor....ticktock....

1QwkSport2.5r

Well, one example involves two engines, each running the same exact pipe. Mach 427 and an SH .28 p6. I haven't degreed either engine yet, but the Mach 427 is kind of a slouch on the HT pipe, whereas the SH .28 just screams. I can tell the pipe runs out of steam at the very top of the .28's rpm, it acts like its got a governor holding it back.. The HT runs fine in the low end but doesnt let the engine really open up on top (either engine in question).

I have several other engines that I need to calculate the compression ratios of, and after I have that data, I'll have a better idea of what rpm they should run at and pipe them accordingly. These generic RTR type pipes work "OK" but there is much room for improvement. I just dont have the cash to buy 20 pipes to experiment with like some people do.

llkoolskillet

So basically your running LRP 28's Upon further research on the HT pipe it shows thats its very similar to an 053 mid range pipe. Why dont you try the OFNA 086 pipe which is a Upper power band pipe? Like I said earlier, the ERCM pipe, be it that it costs more, makes power thru out the entire power band. Why would you want anything different. are you trying to focus on one area of the power band? You know that ERCM makes SB and BB pipes?

savagecommander

Ticktock?

1QwkSport2.5r

I have several engines, both small blocks and big blocks. When these wear out, they will be replaced with better engines. Picco comes to mind.

I'm fully aware of ERCM's offerings, I've seen their website. For what they're asking, you'd think they were made by OS.

llkoolskillet

Why do you say that, cause of the price? The price means nothing compared to the performance gain they bring.

The picco is a great mill with awesome quality. In stock trim its a brutal motor, modded it's a whole different animal

I have two different modded Piccos, one a top end and the others a torque monster. The 053 pipe does what it needs to but doesn't really bring these motors to life. The 086 is strong and wails but compared to the ERCM it's a night and day difference. I'm not trying to persuade you to by an ERCM pipe I just think people should seriously consider them without price in mind. There litterally hand made each one. The power increase is nuts. Even if you find your timing settings you should look into the pipe.

The_Shark

when ever i port a engine, I leave exhaust timing alone, I just add tear drops, open the boost port up a little, smooth out the lip on the sleeve and polish it up.

leave timing to the experts.

Anthoop

Sorry, I thought you would get it, I should of just explained.
Time is what I was referring to, you may know the port area/duration/angle but you need to know how often it will be open. You may have two engines with the same port area/duration but change bore/stroke/rod length and you have two very different engines.

SLAYERDUDE

That's not modding now is it?
WHOOPS! Wrong thread and forum, NVM.

HPI_Savage_RC

Very general numbers:

Exhaust: 85-90° ATDC opening (170-180° duration)
Transfer/Boost: 63-64° ATDC opening (126-128° duration)
Crank Induction: 30-40° ABDC opening, 60-70° ATDC closing (200-220° duration)

Actual values for specific engines will depend on the desired powerband, as well as the intended application (on-road vs off-road).

1QwkSport2.5r

Thank you so very much for that information. I just hope you dont put any of the forum's engine modders out of business.. [&:] LOL. I'm kidding. In reality its not a matter of national security that this sort of information not be shared. I find it rather lame that a question like mine is regarded similarly to asking an engine modder for his/her secrets. Sorry guys, its not rocket science.

Now if I can get a full-wave drag pipe to fit one of my trucks. I didnt think they'd go that high with the exhaust timing, as thats full-wave pipe worthy.. These smaller 2-chamber pipes (helmholz resonators, basically) I suspect they are supposed to act like a full wave pipe, but I'm not so sure. I've never heard any of my engines "get on the pipe" per sé, so I wonder what it takes to get a car engine "on the pipe". With my Aero engines, you can tell an engine is getting on the pipe when the rpm jumps from 13,000 to 16,000 in the blink of an eye. The loads imposed hinder hearing it on a car engine, so perhaps my perception isn't quite right. Nonetheless, I have a better idea of where the timing should be, and then its a matter of finding a pipe that allows the engine to really get on the pipe and run out the way it should.

I have a full-wave pipe I can experiment with, which should shed some light on what the tuned length really should be. I hate the fact that most car pipes are not tunable; ie: header length. This is where you can really cater to the specific engine and really get it to peak out.

SLAYERDUDE

I don't know exactly what a "full wave" pipe is, but you may want to check these out, I like mine.
http://www.extremercmods.com/pipes

Guessing you are a boat and/or plane guy, most of that type have more time and money (retired and rich) than the average car guy and can afford to play with timing and ruin engines until they find something that works, then share the info with friends, us car guys (young and dumb/poor) don't have that type of cash for the most part and that's why we rely on guys like ERCM or "ticktock Neal" do do the footwork for us.
If I could just look up the needed timing specs on a decent .21 truggy engine, I'm more than capable with a timing wheel, file and a dremel.

I've got several old O.S. .12's I could use as test subjects, but that's not going to tell me what I need for a .21 truggy engine, and I don't have the time to properly test and tune my ERCM modded engine as it is...

It's alot cheaper for me to just pay someone to get the results, then reap the rewards of plenty of power and 10+ minute runtimes..

1QwkSport2.5r

Airplane guys are not rich and don't have disposable incomes. Most of the aircraft pilots I've talked to are older guys, living on social security, and have been flying for over 40 years. These guys aren't cutting engines up to max out performance. Many of them try different types of exhaust systems to get better performance out of the engine instead of using the restrictive stock mufflers. Some guys use full-wave tuned pipes, like whats on the boat on the left in this picture:

Other guys use Helmholz resonators which dont give as good a boost as the full-wave pipe, but dont beat the engine up as much either. This is an example of a helmholz resonator, which is basically what most car tuned pipes are.

This is the third type of "custom" exhaust system some guys use. Referred to as a "Mousse Can Pipe". These boost power as well as a Helmholz, but cost significantly less and are half the weight.


There are other types of exhaust options for airplanes and airboats, but cars need small compact exhaust systems, thus the current offerings. The full-wave pipes are big and take up a lot of room, and in the car realm, are usually reserved for drag cars and rail cars. However, if one could experiment with one, you'd be able to find out what your engine really has on tap. The timing of the engine determines the powerband, and the exhaust system catered to the timing (by trimming the header) can truly peak the engine out to get max power from it.

I'm not rich, and I dont cut my engines up. Most of my engines are stock. What gets modified or changed is the exhaust, and the fuel. High exhaust timing needs a short pipe, and lower exhaust timing needs a longer pipe. Put a short pipe on a high timed engine and you will not be anywhere close to peaking the engine, and probably disappointed; and vice versa. All I'm trying to do is get a better idea of what pipe length is needed to get full power from a given engine. Being that I'm not rich like some of the guys here, I wont and cant buy 10 different pipes, most of which are $80+ each, to experiment with. As an experiment, I may order a drag pipe header and tune it on one of my engines as an experiment using the long full-wave pipe, and once it peaks out, determine the volume and length. Then shop around for a pipe with the right volume and length. Obviously a car pipe is going to be much shorter than a full-wave pipe, which I believe is where these 2-chamber pipes come in. Though its counterintuitive to use a longer pipe for higher rpm as its actually opposite of that. The pressure wave travels faster in a short pipe, which is meant for high rpm. Long pipes are for lower rpm powerbands because the pressure wave has a lot farther to travel, which slows it down.

Perhaps this is above most guys' heads. <shrug>

Drag car pipes:

Tunable headers:





Above photos are courtesy of Macs Products. (Macspro.com)

downunder

The problem with any kind of true tuned pipe is that it only works over a very narrow rev range. Below it's tuned rev it's basically just a muffler and above it's tuned rev it can severely limit much more increase in revs. This is where the problem lies with car engines because they're continually changing revs from tight corners to straights. You could tune for lots of extra torque coming out of a corner for much better acceleration but you'd likely find it won't rev as high on the straight. If straight line speed is your main concern then tune for that. There are different types of full wave pipes though. Some are extremely critical but give a huge boost in power over a very limited range while others are designed to give boost over a much larger range but at the expense of less power increase. The red pipe (Jett?) above isn't tuneable so only works at a specific rev, somewhere around 16,000, which is fine for an engine loaded for and only run at those revs.

As far as timing goes, a pipe will work with any exhaust timing. I've used a full wave pipe very successfully with an exhaust timing of 70 degrees BBDC (140 total) but that's for a specific application in a plane. And just a small correction to the exhaust and transfer/boost timings above which should read BBDC, not ATDC .

1QwkSport2.5r

The red pipe I pictured above is a Jett pipe, and is supposed to have a "butter zone" of 15,500-17,000rpm with 17k being the limit - it will act like a governor almost. I understand full-wave pipes will work with any exhaust timing, though the higher the timing and longer the blowdown the better the engine benefits from the tuned pipe. Of course, full pipes tend to make the engines "peaky" and usually makes the transition/midrange rpm too rich. Glow plug selection is critical, IMO.

I have one car that I want to tune for all-out speed and is the basis for this thread. The other trucks I have are heavy monster trucks and benefit from a torque boost, and dont rev nearly as high as the speed engine. It seems the two-chamber pipes I've been using run out of steam at top rpm. They act like governors and limit rpm.

This is all in the name of learning, and experimenting.

downunder

Fair enough, then you'll need a full length pipe preferably and one that's short enough, including the length of the header, to suit whatever revs you're aiming for. At a rough guess I'd say you'd be looking at something like 10-12" from piston face to the first baffle in the pipe. Two chambered pipes are just a pipe with a built in muffler at the end, usually called a Quiet Pipe.

If you want to hear what a very critical pipe sounds like when it comes on then watch this [link=http://www.flyrc.org.uk/record/control_line.htm]video[/link] of a CL speed model setting a new world record. And turn up the sound .

supertib

ideal timing is also dependent on the sleeve design.......A 3 port engine will run a much different timing then a 9 port engine to get the same results as the 9 port..............meaning that the port layout of the engine can dramatically affect how it performs, so much so that the timing of the engine can change quite drastically to get the same results...........I have no issue telling people timing numbers, the issue most people will have it actually accurately adjusting the timing on the sleeve and not doing any damage......... On some engines the timing change is very small, not much more then shaving the chrome layer out of the port.... which can be extremely difficult to do...it is very easy to make a large change in timing, but extremely difficult to make a small change to a individual port

...

Nitrovein

+1
Just cleaning up the ports can change the timing to where the sleeve needs to be brought down again.
Diamond needle files is all that I use In the ports as you control every stroke and have better control over the work that way. It´s always easier to remove material, than it is to put it back...
Dremel is for the crude work.