PISTON AND CAM OVERLAP RELATIONSHIP!
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- čas přidán 6. 09. 2024
- WHAT PULLS IN MORE OF THE INTAKE MIXTURE?
IT IS NOT WHAT IS COMMONLY BELIEVE!
Obtw, I get numerous requests for technical advice and if interested, tex me @ 626 203 2712. Half hour to 1 hour+ rates are available. Most calls go over as posted and it is ok. US Pacific time zone.
I just hope you keep doing these videos. I've been around a long time and done some stuff but everything you explain makes perfect sense and makes me think on a higher level. Thankyou for sharing your huge experience.
Dean, thanks a lot buddy and hope these eye opening subjects helps you with your projects!
Not to mention that he responds to almost every comment 👍
@@robertwest3093, thanks sir.
Thanks for sharing that knowledge Ben. These are the important things that most engine builders/racers don't tell you. Much appreciated
Love listening to gearheads with real world tech experience that know what they're talking about.
Recently been researching the David Vizard "128 formula" for LSA and corresponding overlap. Every test I've seen where they test different cams with varying LSA and timing events has supported his general formula.
He essentially is saying the same thing as BA here, that using the exhaust to fill the cylinder at the ideal time with timing events creates maximum output per engine configuration... Whereas the only thing most "cam experts" point to is duration and lift. Yes they're important, but only in a secondary nature.
Love videos like this!
Thanks and appreciate your viewership from an obviously well informed gear head!
This supports Vizard’s LSA Theory! And quite frankly makes sense....
The ole' Tq vs. Hp scenario, in how long the intake valve remains open After Bottom Dead Center... (Intake Savaging) Earlier Close, (Torque when closing pre 61° ABDC) vs. Later Closing (62° to 73° ABDC ) for improved mid-range & higher RPM Hp. Overlap contributes in initiating higher air speeds, which leads to early cycle air flow efficiency. As appropriately mentioned... atmosphere & cylinder depression are major factors in fill efficiency. Also the Nozzle Effect @ the valve throat. (Bernoulli's Effect) Garden Hose with or without pressure nozzle.
Overlap indeed contributes greatly and also contributes to "overdrawing" the intake charge straight to the exhaust dropping our dynamic compression, out the pipes with new high port intake and exhaust cylinder heads.
Thanks again Ben
Love to listen to you explain all this great stuff.
Always learning from your experience.
Please keep it coming.
Ford power.👍
Where is the heartbeat? Hiding in a corner scared.
Yes sir, them bowties scared of the blue jelly bean.😁🤣 SBF
Many times our pro late spec compression engines have traction issues at the local track. Got to use heavy springs sometimes, we use 6.200 rods typically. Thank you again for educating us.. old builders are going away ..
Thanks Nick for tuning in. I admire circle track builders because they really stretch their engines way more than we drag racers.
ben you're awesome I really like your channel!!
The craziest I have ever seen the world. Thanks for your help
Thank You Ben, my gearhead education continues!
Thank you again Mr Alameda your knowledge is amazing !!!
Really enjoy learning from someone with with such knowledge and passion for this stuff. Awsome
Thank you Justin.
Thanks once again to my friends Dennis and Edward Abejar for introducing you to me. Last time I saw you was at Edward's funeral. You Sir are a modern day Clay Smith.
Thanks Ramiro and are we friends @ FB? I am constantly in touch with Dennis and Edward both real nice guys!
@@benalamedaracing2765 no I don't do FB or any other social media.
I understand and I stay in there to enable others to reach me. Otherwise it could be a mess! lol
It’s finally nice to sit in the garage and make a video.
Another Great Video Ben 😊Thank You
Another great lesson my friend. Thank you for expanding our minds. Much appreciation brotha. Excited to finish building my 9.2 deck drag car project.
Priceless knowledge openly given to all...
Thanks Robert!
Hey ben, just stumbled on your channel. Interesting stuff, you're a likable personality as well. Looking forward to more vids.
Thanks Bobby and keep connected to my channel.
@@benalamedaracing2765 Absolutely Ben, I'll tell friends to check it out too.
Thank you for sharing your years of knowledge! I look forward to your new videos.
Sounds like you and David Vizard would get along.
Vizard has a lot of dyno/flowbench experience whereas I have a little of those enough to know, but a ton of racetrack experience and with wins.
Both have their own merits and therefore cannot be ignored...
@@benalamedaracing2765
Well when either of you speak I listen.
@@williamhenk1030 Thank you again William!
@@benalamedaracing2765 hopefully I’ll get to meet you someday? You know your stuff for sure👍 I met Andy Wood at the No Name Nationals and really enjoyed talking to him. He mentioned us in a video afterwards very cool guy!
I was subscribed to Car Craft magazine for over 30 years. Not once in all those years did they talk about the important areas of power building.
Thanks Robert for noticing what I have been trying to do here in this channel. I worked with Petersen Publishing writers as well as other magazines for many years and they show the differences in power or whatever, but nobody really spoke of the final details of why it did what it did! Also I am aware that there are many writers but very few actual die hard racers that compete in a high level that shows a completely different outlook on engines and tuning etc... I hope I was able to point this out to my viewers...
aaa thanks for your experience.
Thanks as well sir!
Loco Fomoco , bullet that stopped the Chevy heart beat.
Thx again brother
Thanks!
Long rod = less angularity, less side loading of piston skirts, less parasitic drag on the motor. Long rod tends to have the piston dwell at tdc and bcc but real fast piston travel between the tdc and bcc. 429 Ford CJ is the worst combo, 1.72 rod ratio with huge lazy intake port.
Peter, I like long rods for the points you describe and prefer it most if not all the time. The only exception are short rods on an oval or road racing engines seems to accelerate stronger out of the corners which by the way does not show on a dyno tests!
A long rod and a short rod can have the same rod to stroke ratio.
It's the ratio that effects momentum.
We have to keep it consistent for the sake of comparison therefore, using the same stroke but 2 different length rod so as to say comparing orange with an orange not with a banana! lol
Thanks for sharing your experience mr alameda. Peace
Great information my friend. Thank you for all you do.
Another eye opener. Greatly Appreciated
Thanks for sharing your knowledge. always learn something new from you 👍👍
Great information Ben!!!!!!
Ben you did a great job making this video
I feel I should go more towards hard core racing info. What do you think?
@@benalamedaracing2765 absolutely you are a very knowledgeable man I would love to learn more information
Absolutely
Seems like the 4v heads could have different bowl shapes to increase swirl, example, one valve having alot of tumble and filling the bottom of the cylinders as much as possible, then the other valve firing the air against the cylinder wall, to create swirl, with chamber shape and bowl shapes being asymmetrical, yet complementary to one another! It would required stimulation and CNC work, hand porting, and possibly welding, but when the basic rough shape has been discovered, it should not be difficult to repeat!
Well eventually when you have the mock up of the port then when it actually flows will tell you a completely different scenario altogether. One thing I have learned all these years is air will go where it wants to and there are very few things we can do to alter or change its direction.
No Suction maybe people will get it now Ben.
You and I are both on the same line of thought...
I have a 306 with an older flat tappet Thumpr cam installed by the previous owner. I have AFR 185 heads. Compression is not high, not exactly sure what it is as the engine was already in the car. The idle was choppy but clean ( little smell). I went to the track, acceleration was soft. I discovered that the cam was installed 9 degrees advanced. I changed it to 2 degrees. I picked up almost a second and 8 MPH! but the idle is not as choppy and will burn your eyes with so much unburned air fuel mix coming from the exhaust. Ignition timing is 12 initial and 36 total with a mechanical advance. The car is a 68 Mustang coupe, 2900lbs. TCI C4 3000 stall, 4.11, 26” tall tire. I’d like to clean up the idle and pick up some ET. Best is 12.5 at 108. Should I advance the cam more?
If it was 9* adv. depending on lift it would have hit the intake valve to the pistons. If you placed it at 2* your top end would improve at the expense of low/mid range power. An advanced cam will do that but it will sign off earlier at the top rpm but give a lot of response not soft so we are not getting the complete picture here. What is your compression?
Not sure. Cranking compression is just over 100PSI. Maybe 8:1?
I say 9 degrees because that’s what the crank sprocket was set at. It had 3 key slots 0, adv 9, ret 9. I replaced it with a sprocket that had keys at 2 degree increments. I set it a 2 adv. the result was more power from tip in but eye watering exhaust.
@@benalamedaracing2765the pistons has a dish in it. That may explains it.
How ya doing Ben? interesting on the short rod vs long rod. On my 306 build for road race I wnet with a 5.4" rod for what I thought would help side loading stresses at higher rpm, not sure if that is even an issue. Also the 4.6 mod engines have a fairly short rod ration if I remember correctly. looking forward to the header video.
It is really one of the secrets of the success of the 302HO having a short rod and stroke which for most instances will outrun and IROC Z with a 350 back in the day! The longer runners however ugly on the factory intake with the right hand side facing throttle body, actually boosted its low/mid range power compared to the beautiful to look at TPI Camaro intake! Imagine that the 305 did not stand a chance and the 302 with about 50 odd cubic inches shorter was an impressive engine that kick started the 5.0 revolution.
@@benalamedaracing2765 Ben I know all this for a fact. In 1987 I had a 1984GT T-Top and the 305 GM cars were never any competition, the 350 IROC's and GTA TransAm were basically a drivers race, whoever got the jump would hold the lead. My mustang was 100% stock. I'd street race any thing and every thing. Lots of fun stories, all of them totally stupid.
@@chestrockwell8328, that is the best opinions from experience and you did that and that cannot be ignored or disputed!
Seems the engine with all the proper parts at the optimum rpm could experience higher than ambient pressure in the port above the valve, and possibly get higher than ambient pressure in the cylinder with all the correct parts the volumetric efficiency being 100% possibly slightly more, i
Hear the new LT6 is over 100% volumetric efficient I'd love to see that engine in a Camaro and a SS, truck! Maybe go cross plane for the truck, but keep the 4v heads maybe go to 6 litres , but a 6 speed truck with 4v heads and a more traditional intake, it should make around 400hp stock maybe more in a Camaro, clear 500, and 750 + with a supercharger, it would be awesome, and there supposed to be a next generation V8 coming to Chevy /GM soon, possibly 2025, hopefully it will be a 4v dohc based on the LT6 some what,
Anything is possible and just got to have a working prototype and see what you have. Dynamical vibrations and frequency can wreak havok on any design and this is one subsurface stress that few understand or can effectively deal with it. I had one friend years ago said designing an engine is easy pickings and boy was he deadly wrong and blew up everything he built.
Kevin’s Burgers in the valley.I miss those days.
Was that in Van Nuys or someplace sounds familiar and am starting to forget! lol
I think it was canoga park, maybe Saticoy and mason or winnetka
I think it’s a sushi place now.🥹
@@joshuagarvey9362 better to have a fond memory than nothing at all
I'm one of your true belivers in how to approach an engine build. I'm very much a beginner in understanding the timing function of a cam grind to the piston location a full engine cycle . I found on CZcams Scott Hatch(channel) episode "Camshaft events power and torque cadillac 472/500". Is this how you see the cam/piston location relationship in a full cycle?
Could you send me the link so I can check it out?
Is very little overlap bad for carbureted engines?
It really depends on the cylinder head you are using. Traditionally old skool heads requires a lot of overlap while the new type race heads uses hardly any overlap.
Check my videos on cylinder heads and I explain it there as far as overlap. I think the video is about low and high port heads.
Thanks for knowledge! Can you talk about overlap size? And LSA size?
I will be doing a video of your suggestion and it will be interesting because now our all out NA camshaft looks like a turbo grind! lol Stay posted and thanks for supporting my channel.
😂👀 The people that don’t know the difference in “low pressure” area and “suction” are the same people that think engines like a little “back pressure” in the exhaust! 😂😂😂
Great content! Thanks Ben!
That is a good video to make about back pressures which I know you hear people say "you need back pressure"! lol
Hi tech info explained in a way that anyone can understand it. That yellow mustang was crazy fast and made some power. What would be your go to intake for a 347 210cc ported heads at the track along with cam specs? If u have any 1.7s roller rockers that u would be willing to sell im your guy 😁 Keep the info coming. Maybe you can explain all of the cam specs and their overall impact on an engine and how to spec your own cam out on a build without having to seek advice 😁 but I would like your advice on the best cam for my engine
I prefer the Anderson camshafts for their power and reliability. Call them and give your specs and they will get real close to ideal. I prefer them and Isky which I get specific to my goals otherwise the former is next best if not the best out there!
Thanks for sharing your knowledge. I'm very interested in more on the subject of overlap, and recommendations. 408 Windsor hot street motor, AFR220's 2.10 intake valve/4.030 bore /10.25 static comp/6.20 rods/ RPM airgap/carbed NA/ 1 3/4" header primaries 28-34" long. I'm at 105 LSA .610 lift in my mind but can't decide on overlap, likely 55 to 60 degrees and duration falls where it may.
This combination seems destined to be a strong runner! Anyway call Isky and talk to Rod, 310-217-9232. He will refer you to a grind that they make and just mention my name. They hit it on the mark all the time I have used them and they have a vast number of grinds for your combination. Otherwise another option is Anderson Motorsports for a non custom cam they are also very good!
@@benalamedaracing2765 Thankyou for your reply. After watching many of your videos I'm thinking I need to go closer go 11-1 on my static compression ratio. I appreciate the tip, I'll give him a call. I've done the math here after my initial comment and my Crower designed cam specs .624 int/.611 ex. 250 dur int. @.050. 256 dur exh @ .050. 105 LSA shows that my cranking compression would be in the 220 psi area, too high for even this 2300 lb AC Cobra.
Proof that swirl isn't everything. Overlap is key
Agree!
Thanks bossing..
Thanks for supporting my channel! Salamat as well.
Thanks for sharing.
Although some of what you say is unproven old school thinking and some of it is plain wrong. For example, pretty much any half decent 4 valve head motor makes more torque than 2 valve head.
Saul, what I am implying without the aid of "variable cam timing", a 4 valve or even a Hemi/Pent Roof layout will be at the mercy of low end/mid range torque blues.
The straight path of intake/exhaust facing each other makes this design susceptible to "reversion" due to the ability of the spent exhaust to go back to the combustion chamber, And I did not even hardly touched on the basic absence of swirl on these particular heads. Worked on a team 24 Hours of Daytona/12 Hours of Sebring Mercedes Benz Endurance Team's cylinder heads/intakes and disabling the cam controls kills much of the response and mid range. I will highlight what I came up with in regards of boosting this flat spots in the rpm range with some interesting changes...
Thanks and appreciate your input means a lot to me.
What is the optimal R/S ratio?. Drag Racing I have shot for 1.7 RS ratio with the FE head. Roller cam. and a 2x4 Tunnel Ram.
I am concerned with R/S ratio specially if I will be turning a lot of high rpms! Otherwise on the streets it can be somewhat low without major issues.
@@benalamedaracing2765 I find anything between 1.53-1.55 on the street or track.Shifting 8000 rpm plus, with no problems.This with a solid min wall thickness of .200, .250, and a cyl wall finish to support oil retention. I like short hang time at the top, many others will disagree.
question how do you get swirl or tumble for that matter ?
Depends on the port angle and bias or the combination of both. If it comes in a little sideways that can create those two mixture motions...
Mr Ben do you have an email address some one could contact you about picking a cam and tq converter combination for us? I realize there is a consulting fee
Call Isky @ 310 217 9232 and ask for Rod or Nolan. Mention my name so they know you are for real and they will get you a grind exactly matching your combination. I always dyno an engine and these will give your converter guy accurate info, as opposed from just buying a 3K stall and expecting it will do the same for you or everybody else which is a hit and miss.
Can I do 4 ° advance on timing gear 8 way key?
You can depending on your valve to piston clearance specially on the intake. How much lift and is it a flat top piston?
@@benalamedaracing2765 ls 5.3 bootleggers cam 2005 gmc on carburetor..
Stock dome piston I think..
How to do overlap? Please show me piston to vavle and fly cut piston??
Why don’t you street race.
I did but not much when I was young. I ended up racing big Suzuki's and other pocket rocket motorcycles on nitrous on the streets. When you dispatched several of them even on slicks and wheelie bars soon enough no cars will race you! lol
Then I got in @ LAPD and that was the end of that fun times.
How is it best to contact you Ben? Ive sent you a message on Instagram
Refer to the cell # above for contact info. Admin.