Author Topic: roller cam? (Read 23449 times)

amc49 · « **Reply #60 on:** April 17, 2014, 07:14:03 PM »

The links are interesting... .............

Magnaflow..... ........'Answer: Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.
Not true. Due to a variety of factors, extensive testing is required.'

So, how can they state all that as perceived fact if the last sentence is true?

.............. ..........LOL

The second link, exhaust videos........ .....problems again. They simply take the same 'certain figured mass of air' amounts and plug them into a formula like you do with trying to find the ideal carburetor size for a certain engine size. It DOESN'T WORK. My old 360 ATX Javelin figured out at a 600 cfm carb at 5000 rpm, the stock Ford 4300 on it had 650 cfm, huh. I put a 800 cfm Holley DP on it and the car dropped a half second in the 1/4 mile and ran great even at lower wide open throttle conditions (3.15 gear) , in short the engine loved it. Couldn't make it bog at all, it pulled hard from 2000 rpm. Over the years I have tossed the prefigured carb size out again and again, first thing you find out is that all engines are NOT created equal, A GM or Ford or Mopar engine of same size will often perform radically different with same size car even if it is optimized for that particular engine. I found that SBF like 302 couldn't handle the same big carb I ran on my crap little 304 AMC with its' puny 1.78 and 1.40 valves. Boss 302 was a totally different issue though, that car loved the bigger carbs, we ran an 850 on it until the tunnel ram with two 750s on it. It's all about the total combination picked there.

People keep saying you have to have the 'velocity, it's all about the velocity' but it's not. When you go for hi-perf you look for 1 inch or less of vacuum (surprise! less velocity) at top rpm showing correct carb size and as low a restriction exhaust (open if possible) as you can get. When you start talking this or that velocity you are heavily giving away power there to me, it all becomes a compromise, what will you give up in performance to get this or that in real world useability? Velocity in the intake means you have restriction, same thing in exhaust. I'm not saying it all is bad but if after maximum power it is. You then draw the line as to how far you'll go; the tradeoff.

amc49 · « **Reply #61 on:** April 17, 2014, 07:39:34 PM »

On the subject of noise......... .......there is a quality of noise side to that, you hear say leaking exhaust that is louder but sounds like crap, that is no better and may run worse. Tuned engines though will develop a certain note that to the trained ear instantly makes them stand out, think Nascar. I love to hear the in car sound bites they have there. I think in terms of bike stuff where you can actually tell what the rider is feeling by listening to the engine as it runs, at some point it begins to blend together in that certain sound that has wave tuning coming into play all over it. When the individual exhaust pulses disappear and then noise turns into a solid howl or roar. The engine at that point actually begins to get louder, the waves are all in synch with the hard parts then. Most exotic I ever got to play with was Honda CBX six with 6-1 header, I see why so many of those Italians left their wives for a V-12 engined car.

If you keep the velocity up in the intake and exhaust sides of the engine you don't get or far less of that. Wave tuning cries out for both sides of engine as unrestricted as possible. We used to run simple bolt on header mufflers back in the day and I can personally attest to how you can get another 75 hp. by simply pulling a best of the best full exhaust pipe system off the car and replacing with those. More than one vehicle, hell the Boss 302 picked up MIDRANGE by dropping the full pipes, we ran it forever with two big diameter Cherry Bombs only after that for years. So, keep talking about velocity in the entire pipe, you lost me there.

dick1172762 · « **Reply #62 on:** April 17, 2014, 08:29:37 PM »

EXHAUST. If you really want to understand / use / be helped by it, go to http://www.maxracesoftware.com and get Larry Meaux's "Pipemax" software. And if that is not enough for you, get your self a copy of "Design and Simulation of four-stroke Engines" by PHD Gordon Blair. It is SAE # R-186 and 825 pages of all there is to know about exhaust and induction.

amc49 · « **Reply #63 on:** April 17, 2014, 08:48:20 PM »

Got the book BTDT.......... ......that guy is plenty smart.

Wittsend · « **Reply #64 on:** April 17, 2014, 10:27:29 PM »

AMC 49, I think we are getting to the point of comparing apples to oranges. The poster was discussing 2,500-3,000 RPM range as a daily driver. You are discussing race (or near race) cars at wide open throttle. In the end 98% of guys will just go to the muffler shop (or do the work themselves). They will likely randomly select a pipe size between 2" and 2-1/2" with little reason behind the decision.

So, I'd still take the "velocity" perspective over say..., the supposed need for "back pressure" any day (not that anyone mentioned that argument). At least for me that is about as complicated as I can mentally get. The likelihood one would benefit a daily drive based on race experience (or reading a 825 page book) is probably far less that what they "believe" they have benefited going to any larger exhaust. Don't get me wrong, I can appreciate experience and knowledge. I just think it needs to be applicable to the value of the task at hand. After all we are talking about near stock Pinto's going down the road between 25 MPH to 65 MPH.

dick1172762 · « **Reply #65 on:** April 17, 2014, 11:07:14 PM »

I tried to shut this down on reply # 28. Maybe now?

Pinto5.0 · « **Reply #66 on:** April 17, 2014, 11:35:07 PM »

I was always taught that in a non-turbo engine operating at a moderate & steady RPM that a certain amount of backpressure was desired to reduce turbulence & keep velocity up in order to fully evacuate the cylinder of spent hot gasses. The cooler empty cylinder then draws the fresh intake charge better than one contaminated by leftover combustion.

A Pinto engine is probably 85-90% efficient on it's best day where race engines exceed 100% VE so they benefit from an open exhaust with little restriction.

Turbo engines pressurize the intake charge & operate well above 100% VE so the free flowing exhaust with no restriction is preferred.

amc49 · « **Reply #67 on:** April 19, 2014, 12:10:02 AM »

Most race engines do well to exceed 85-90%. Why VE is always at a lower rpm.

Necessary back pressure as understood by most is a myth, I can show it several ways, but open headers pretty much lays that to rest. The idea developed from minds that did not understand how exhaust works. Look at when the idea began, in the early part of the century, we've learned much since then.

What works on race cars works to a lesser degree on street ones as well.

'They will likely randomly select a pipe size between 2" and 2-1/2" with little reason behind the decision.'

Yes they will, but not me. Not nearly the first time I don't follow the crowd either.

FYI, these engines are too small. To get anything more than maybe 25 easy bolt on hp you WILL be going toward the race end of the spectrum, there is no way to pick up more power without shelling power band as a consequence unless you turbo. Four cylinders get b-tchier and more quickly than bigger engines do and smaller size only aggravates that more. Why same cam timing in a bigger motor will idle smooth but lopes in smaller engine.

I digress as usual so I will shut up, thanks all that listened to the rave.

Srt · « **Reply #68 on:** April 19, 2014, 03:56:40 AM »

interesting thread. one thing that is obvious is the enormity of opinions on what works.

here's mine: if it feels good, go with it.

if it sounds good, go with it.

what else can you ask for?

dick1172762 · « **Reply #69 on:** April 19, 2014, 09:14:44 AM »

RIGHT ON!!!!

amc49 · « **Reply #70 on:** April 20, 2014, 06:25:57 AM »

Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve.

Wittsend · « **Reply #71 on:** April 20, 2014, 06:38:39 PM »

Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve."

Which..., (unfortunately)..., brings us back to velocity. Ok, I'm no scientist, or expert, or anything, but the theory goes as such (for the benefit of those who don't know - or those who hear that "backpressure" is necessary):

On the exhaust stroke the piston is slowing (and in fact, for a fraction of a second, stopping) as it approaches TDC. The "push" of the piston becomes less effective in removing exhaust gasses. However, as the exhaust gas is moving down the manifold (header), tailpipe etc. the momentum helps to void (draw out) the burned gasses from the cylinder. The best way to have that "drawn out" momentum process is to have the exhaust moving as fast as possible (velocity).

So, this is where pipe size becomes tricky. Too big a pipe and the momentum drops off fast. Too small of a pipe and the momentum is hindered (in relation to its volume) to moving its fastest. Ideally the pipe diameter would keep expanding and contracting as needed. That way you could get maximum velocity dependent upon the volume of the gasses. The expanding pipe isn't going to happen so any pipe size is a "one size" compromise.

Say, someone goes into the muffler shop and asks for a 3" exhaust. They state, "you won't have enough back pressure." What they really mean is that you won't have the best velocity of exhaust gasses for a street driven car. Now to be fair, compared to a 3" pipe, a 2-1/4" pipe may actually increase backpressure as an end result of having higher velocity. But, increasing backpressure is not the goal, increasing velocity is. The tricky part is to have the benefits of increased velocity without the detriments of increased back pressure.

Now, that is likely "Basic 101" on the subject. There is the factor regarding the open and closing of the valves that generate pulses. There is the factor of overlap (where both the intake and exhaust valves are open at the same time). And that is probably only "102" on the subject. Apparently there is an 825 page book on the subject. And, after all that theory there is "real world" experience. Certainly for me WAY beyond my comprehension and thus my ability to apply. But, when much is on the line applying the upper end of this subject is applicable.

Anyway, my goal is just to point out at the bottom end that backpressure is not the goal. And, that (in a street driven car operating at various RPM's and loads) ideal velocity is fleeting. AND, that this basic understanding is just cracking the ice on the subject.

Now, do you all love me or hate me???

amc49 · « **Reply #72 on:** April 20, 2014, 09:26:27 PM »

LOL........... .........

I agree with the top half of that but not a lot of the bottom half. This whole pipe velocity misses the major point like so many of the discussions do. The point is this. You want velocity until you get to the end of the tuned pipe length and NO MORE, anything beyond that is later pipe inhibiting the earlier pipes' performance. If you can trick the engine into thinking the exhaust has hit atmospheric pressure then the exhaust tuning works like gangbusters, indeed the engine thinks any header there is open. The atmosphere has no velocity to it at all. so what happened there? And the maximum power producing condition.

No one qualifies the pipe velocity statements with that phenomenon at all. They just continue to assume it must mean the ENTIRE pipe must be high velocity and simply not so. The major reason why? Once you have passed the tuned length all else there is fluff, there will be no real effect. You CANNOT get tuned length open pipe performance with full length pipes, anyone trying has pretty much failed there. When you look for velocity in tailpipes you have restricted the pipe further up to kill power, end of discussion. Why? Because if sized to make velocity they will stop the exhaust plug from firing through the pipe earlier and further back as fast as it can. It wants atmosphere (zero resistance) there, no amount of velocity later on can replace that full open condition. The later pipes' area to be plowed through will inhibit the exhaust pulse as the gases stack up in the pipe to be shoved further back, sizing for velocity only makes that worse. Velocity later on in the system will not aid one other big tune of simulating open pipe, the pressure backflow that results in a positive pulse reversing to go back up the pipe and acting as a pipe stuffer to limit the loss of mixture at the end of overlap, full length pipe pretty much totally destroys that, it does not happen. Velocity does nothing for that at all either, in fact it squelches the effect. But short pipes like straight through header mufflers will let some of that happen.

You wave tune with short pipes, once you must use full car length pipes you must give up true wave tuning, all you can achieve is flow enough to simply let engine breathe easier, there will be a big loss in power with the wave tuning effect gone. Pretty much impossible to get around it, but a trick or two can help it get better.

Enter the difference between true sound wave tuning and vacuum tuning ala multi-tube headers. Two totally different animals.

Lemme guess, I went and made it worse again right?

Wittsend · « **Reply #73 on:** April 20, 2014, 10:21:41 PM »

Well, again I keep going back to the original premise of a Daily Driver with a relatively stock 2.3 (... a Ranger roller cam and header). The owner needs to replace the exhaust and is contemplating what size exhaust and legal muffler to run (to the rear of the car). None of the wave tuning you mention applies because, as you note, the run is too long and it becomes irrelevant.

I'm truly not trying to be obnoxious, but given the exhaust described above (see underlined) what would you recommend tubing size wise? And why? - I mean some tubing size needs to be selected before the work can begin. And regardless that none of the science of the wave tuning is applicable there still should be some form of reasoning (no matter how minor) in the size selection.

amc49 · « **Reply #74 on:** April 20, 2014, 10:37:08 PM »

Depends on how many mufflers, fours commonly use two to really quieten things. Probably 2 or 2 1/4'', what I've used with good result. Using only one muffler may well be too loud there. Inline fours make more exhaust harmonic noise than other engines, the 180 firing order......... ..2 inch on single muffler, the bigger one with two.

waldo786 · « **Reply #75 on:** April 21, 2014, 10:21:21 PM »

I am actually looking at doing an 86 ranger exhaust manifold as I'm hoping that's just a bolt in for the car and I imagine it flows better than stock. I'm in the process of ordering a ranger roller cam, and we'll go from there. I have the offenhauser intake and a holley 390 carb.

Wittsend · « **Reply #76 on:** April 21, 2014, 11:16:25 PM »

Are you getting the cam/rollers new? What is the going rate? I saw a used set on Ebay for $99. Wrecking yards would likely be cheaper. We have Pick Your Parts around here with their 50% off sales. I got the cam/rollers/lifters out the door for just under $30. I guess I'm so tight with the dollar that it pains me even when it's another mans money. LOL

Srt · « **Reply #77 on:** April 22, 2014, 03:21:46 AM »

go with 2 1/4" pipe a muffler at the rear (walker makes a good one) and if you notice a harmonic vibration graft in a 2 1/4" perforated core straight thru (glasspack or similar)(make sure the core is 2 1/4" diameter too) in the straight section of the exhaust pipe ahead of the rear axle.

make sure you run the exhaust all the way to the rear of the car or you WILL have a lot of noise inside the car.

Pinto5.0 · « **Reply #78 on:** April 22, 2014, 07:28:18 PM »

Quote from: amc49 on April 20, 2014, 06:25:57 AM

Uh, back pressure has nothing to do with evacuation of cylinder, that requires NEGATIVE pressure to achieve.

That was actually quoting a couple different articles that state how backpressure decreases turbulence which keeps velocity up.

71HANTO · « **Reply #79 on:** April 22, 2014, 08:58:15 PM »

Just throwing is into the backpressure mix. I just bought a V6 muffler that I am going to use BACKWARDS to reduce the backpressure on a turbo'd 2.0L. I know some mufflers are directional but Pinto ones don't seem to be. This based on looking at (into) my original 71 muffler. It's hole'ier than the Pope and needs replacing. I think two tail pipes with add a little extra touch and sound better. To me, stereo usually sounds better than mono. Feedback good or bad welcome. I bought this muffler cheap so no big deal if I can't use it.

71HANTO

waldo786 · « **Reply #80 on:** April 22, 2014, 11:44:21 PM »

Wittsend, I actually was introduced to someone who sells the thru our forum. I bought one with the followers for $172 shipped. Not as cheap as yours but I also don't have all day to go out and pull one either. I know what you mean about saving money. I do everything I can to try and save. I think I do pretty well overall.

Pinto5.0 · « **Reply #81 on:** April 23, 2014, 03:39:17 PM »

Quote from: Wittsend on April 21, 2014, 11:16:25 PM

Are you getting the cam/rollers new? What is the going rate? I saw a used set on Ebay for $99. Wrecking yards would likely be cheaper. We have Pick Your Parts around here with their 50% off sales. I got the cam/rollers/lifters out the door for just under $30. I guess I'm so tight with the dollar that it pains me even when it's another mans money. LOL

I got one off ebay with lifers, rockers & cam for $99 shipped. The closest pik-a-part to me is an hour each way meaning 2 hours time & $12+ in gas just to see if they even have one. In the end the $99 isn't that expensive considering.

Wittsend · « **Reply #82 on:** April 23, 2014, 06:44:06 PM »

Again, I often forget my good fortunes. I haven't had to work (most) Fridays for the past 23 years. That said, the closest Pick A Part is nearly 45 miles away. And it is $10 in gas and $6 for yard admission (there are three self serve yards in the area). So, yes, I'm $16 spent even if I don't get anything. They also don't allow core exchange on 50% off sale days (which is the only time I go). So, I often wind up eating my core charge because I'm not spending $10 in gas plus 2 hours of my time just to get my $10 core refund. Sometimes I come home with a bunch of stuff. Other times nothing.

I'm also about 60-70 miles from the huge Pomona swapmeet. But that is $20 gas, $10 parking, and $12 to get in. So, I'm $42 in the hole before I buy anything. And, the last time I went, I really didn't get much. So, while I'm a confirmed penny pincher I can understand the value that comes with paying more at times.

Ironically there is the "Largest Mopar Swap west of the Mississippi" (as they bill it) that is only $8 in gas, free parking and free admission. I get more there simply because many parts are generic. An electric fan is an electric fan. It is were I got the fan for my Turbo Pinto (for instance). In fact, I got a complete gasket kit for a Ford 289 at this Mopar show!

Srt · « **Reply #83 on:** April 23, 2014, 08:19:50 PM »

Quote from: 71HANTO on April 22, 2014, 08:58:15 PM

Just throwing is into the backpressure mix. I just bought a V6 muffler that I am going to use BACKWARDS to reduce the backpressure on a turbo'd 2.0L. I know some mufflers are directional but Pinto ones don't seem to be. This based on looking at (into) my original 71 muffler. It's hole'ier than the Pope and needs replacing. I think two tail pipes with add a little extra touch and sound better. To me, stereo usually sounds better than mono. Feedback good or bad welcome. I bought this muffler cheap so no big deal if I can't use it.

71HANTO

charles what ID is the inlet? been a while since i have laid any pipe or hung any mufflers but you may have to flip the inlet to one side or the other. the bracket on the muffler (if you can) should be relocated to the rear, outlet end to take advantage of the stock hanger which IIRC is located to the rear of the stock muffler.

i used to bend exhaust pipe for a living (many years) and a muffler like you have is something we hung a lot of back in the day. gm cars with the small v6 used a muffler similar but with smaller inlet & outlet pipes.

it should work just fine.

just remember, 20+ lbs at the top of 1st and through all the rest of the gears will open your eyes wide.

i used to peg a 20# VDO boost gage with ease with the setup you have. it WILL be fun!!!

Pinto5.0 · « **Reply #84 on:** April 23, 2014, 08:25:04 PM »

I always weigh the cost of acquiring a part including labor into what I'm willing to spend to have one sent to me. Usually it's only 25% more to buy it off ebay versus digging it out of the boneyard myself. It's not penny pinching as much as work is running me into the ground Sunday afternoon through Friday morning so my spare time is limited. I have trouble finding time to mow my grass LOL

waldo786 · « **Reply #85 on:** April 26, 2014, 10:53:40 AM »

I know what you mean Pinto5.0. I work 10-12 hour days most days typically, and finding time to do things is not easy. I'm willing to spend a little more for the opportunity cost, although I think it'd be cool to be able to go to the u-pick it. Unfortunately there aren't many of those around here (DE), so it's usually just easier to buy them through other means. I got a mid-90's ranger header from the same guy for $95 shipped.

71HANTO · « **Reply #86 on:** April 29, 2014, 02:30:01 PM »

From SRT:

"charles what ID is the inlet? been a while since i have laid any pipe or hung any mufflers but you may have to flip the inlet to one side or the other. the bracket on the muffler (if you can) should be relocated to the rear, outlet end to take advantage of the stock hanger which IIRC is located to the rear of the stock muffler."[/size]

Steve, I just got the V-6 muffler delivered and the inlet (outlet) is only 1.75. It looked bigger in the E-Bay pictures. I was hoping for at least a 2 incher. I could try to mod it or I may need to send this muffler on. It is date coded 12/1978 without a speck of rust.

71HANTO

65ShelbyClone · « **Reply #87 on:** May 01, 2014, 10:31:50 AM »

Quote from: Srt on April 22, 2014, 03:21:46 AM

go with 2 1/4" pipe a muffler at the rear (walker makes a good one) and if you notice a harmonic vibration graft in a 2 1/4" perforated core straight thru (glasspack or similar)(make sure the core is 2 1/4" diameter too) in the straight section of the exhaust pipe ahead of the rear axle.

Another (usually cheaper and lighter) possibility is to identify the frequency of the harmonic resonance and build a suitable Helmholtz resonator to cancel it. I haven't tried it yet, but all the reports I have read are quite positive from Nissan Titan trucks to Fox3 Mustangs to late model Camaros. Some cars came stock with these noise-cancelling resonators. The Honda S2000 is an example.

It's really easy to identify the resonant frequency. All you need is a clean digital audio recording of it and free audio software like Audacity.

Wittsend · « **Reply #88 on:** May 01, 2014, 12:30:21 PM »

Interesting. I have a '73 Valiant 318 that dumps two, 2" pipes into a single 3" pipe through a Flowmaster 50 and then out the back. The drone is unbearable from 2,000-2,600 RPM. These resonators seem like the water hammer pipes one installs in plumbing. I didn't read far enough to grasp the science behind it (and I probably wouldn't understand it anyway). But, they all seem to be fixed length pipes. I think I'd make mine adjustable (pipe sliding over pipe) since my experience has been that "math" and "real world experience" can often be two different things.

65ShelbyClone · « **Reply #89 on:** May 01, 2014, 01:20:06 PM »

Quote from: Wittsend on May 01, 2014, 12:30:21 PM

These resonators seem like the water hammer pipes one installs in plumbing.

They look the similar, but don't operate in the same way.

Noise-canceling resonators operate on the principle of constructive and destructive interference. The drone in an exhaust is caused by constructive interference that makes sound waves stronger when they "stack" upon each other. Destructive interference does the exhaust opposite. Kind of like 1 + (-1) = 0.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Noise-cancelling headphones attempt to do the same thing electronically; they duplicate the noise audio 180° out of phase so it cancels the ambient noise.

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Author Topic: roller cam? (Read 23449 times)