No pain at all, in fact, is a refreshing welcome to the usual responses I get when presenting 'new' information to the general population of 'racers'. To answer your question, it is the exact same engine profile, one graph taken at .006 and the other at .050. What I usually do is simply take the two and average them to get a better overall representation of suggested engine behavioral patterns. I used the 'Stage 1' heads as a default model, since I already happened to have that file on hand. I have other head profiles. The program doesn't take some things into consideration, and I have to make a 'best guess' at some things, backed up with experience, research, knowledge, and a bit of intellect tossed in for good measure. The program isn't necessarily "Buick friendly" in terms of the unique design characteristics not found in other engine designs, so again, a bit of mixing and matching is required. The intake I choose to use is the 'high flow dual plane' which I like to assign to the TA Stage 1 intake. There are others, such as the 'standard flow' (more like a chevy intake with shorter runners), and then the 'high torque' which is more in line with the Buick 350 intake. I usually average the results from standard and high torque to get a more realistic result for a stock Buick 350 iron intake. As you may imagine, there ends up being a lot of numbers to average and discern when doing engine combinations other than straightforward designs, and so can take up a lot of time finding an end result. By far the easiest way (head wise) is to simply use the standard sized valves, particularly if all you're going to do is massage/light port work. The Buick 350 needs a LOT of work to get 400+ hp out of it, as by its very nature is a grunt engine. Getting 325-375 hp is pretty easy though, along with well in excess of 375-425 ft. lbs., which will make most people happy (and is damn impressive out of a 355 CID engine). This will of course change once those aluminum heads become available. Even if they do not meet expectations, should be far better flow wise than the iron heads they're replacing, and 400+ hp will then be much simpler to achieve. Preliminary 'on paper' testing shows a hot roller cammed Buick 350 with those aluminum heads, SP3 intake, and large tube headers can expect over 600 hp and almost 500 ft. lbs. from 5000-7000 RPM, N/A. This is projected, and may fall short, or may exceed. We'll see. These numbers should come as no surprise to those who are in the know...there have been others who have achieved close to these numbers with hogged out iron heads and fabricated single plane intakes. Anyway, just some thoughts. Gary
I don't remember the instructions that came with that program, it was new a long time ago. My memory might be way off, but... I thought they want you to use the .050" #'s when you can't find seat to seat specs. I think you lose some of the programs full abilities with those. I have found them to vary wildly depending on the combination, along with the occasional "No way, not happening..." moment. It only takes a few minutes to find seat specs on the net, and the margin of error on a GIGO program is wider than a degree or two guesstimate. It can be a decent tool if used right, thanks for taking time to do that!
My pleasure. One of the ways I can contribute to the community. The program isn't free; it requires a purchased license key to activate. I never used any instructions though. I'm somewhat computer literate and used some common sense with it and just tinkered and taught myself. I taught myself German (Deutsch) too, but that's another topic. Some thoughts on its use: I think a lot of people use the .050 because for the most part, it's the closest and easiest way to determine performance camshaft behavior. Things change with milder profiles, or wider lobe intensities, since there's more time between travel distance from seat to .050. I use .006 for 'seat' or 'advertised' even though it's not, but I figure it's close enough. It only made sense to take the two and average them to get a better figure for engine behavior, and even THIS does not tell the whole story, but again, I figure it's close enough for the general idea. They use a 'H.P. manifolds with mufflers' setting, which seems to be for the log type manifolds typically seen with most other maker's designs. I assumed "H.P." represented 'high performance'. If an "X" pipe is assumed to be used, I'll typically use the H.P. manifolds and small tube headers with mufflers and average those, to mimic the scavenging effect, but not as good as straight headers, so the figures will be a bit less. This is a 'best guess' and is as good as anyone could do without actually testing the physical parts. Other factors come into play as well, but best to use some common sense, knowledge, etc. and you can get a decently close guestimate. So I can have up to 8 sets of numbers to average. Two types of exhaust, two types of intake, and the two different ratings for each of those (.050 and .006), totally up to 8 sets of numbers to average. I do RPM powerbands and hp/tq figures this way. It seems to come out pretty close, based on stock engine's output from various engines used as a baseline for comparison, and considering the lowered compression those engines typically had from the factory. These are also ideal numbers, within perfect environments, but also do not take other things into consideration. They're just the raw numbers based on airflow and RPM. One thing I can say is that flywheel figures from the books were fairly close to accurate, given the proper compression and not the actual compression they came with. The books are inflated for marketing purposes, using a 'projected' figure of what the engine 'should' do given the proper and ideal circumstances. A low comp Buick 350-4 produces between 350-370 ft. lbs. and 250-270 hp with a true 8.5:1 static compression and the Federal Mogul cam. A high comp Buick 350-4 produces between 370-390 ft. lbs. and 280-300 hp with a true 10.25:1 static compression and the Federal Mogul cam. Both engines assumed with the aforementioned averages. Both engines make torque between 1500-4000 RPM, peaking around 2800-2900 RPM, and hp comes on strong from 2500-5000 RPM, peaking around 4600-4700 RPM. All heads I've seen (even heavily ported ones) show the vast majority of airflow between .200-.400 lift. Stock heads have squat after that, and the ported ones gain peanuts from .400-.600 when compared to .200-.400. Usually 100+CFM is seen between .200-.400 while only 20 CFM (at MOST) is seen from .400-.600 with heavily ported heads. These disparities are even greater with milder port work. So while larger cams will still maximize power with more lift, you run into diminished returns on increasing lift beyond .450 on symmetric lobes. Gary
I've gone back and attempted to model builds previously done using as much real world data as possible, such as track performance or flow bench readings. Take all that with a grain of salt as one admits to going through a learning curve with tuning or accepting that their combo (or customer's) might not be as optimized as could be. We all know there are many affected factors with the vehicle, etc.... It is my observation that using the program in the .050 settings skews the model, and seems to make the cam act bigger than it is, for whatever reason. Programs do seem to work well with stock and mild combos, air starved maybe? I mostly base my builds off of the heads and the associated calcs as the hp and tq peaks are derived from that. The programs are a great way to quickly watch the shape of the torque curve, to help you steer it where you want to, and hope it seems to do it in the real world. If I am undecided on what specs to use, I'll slightly exaggerate something like an airflow # or perhaps a better intake/header to see what the engine MIGHT want, knowing that the hp/tq #'s are irrelevant. Then you can decide what things might help driveability, mileage, or whatever....if WOT doesn't vary much. Keep in mind the basic programs don't account for different header specs, scavenging, intake ramming, mixture motion, or any part throttle behavior. Many things tough to measure, but do have an effect on things. Basically the # estimate is less relevant than finding some kind of gross mismatch mathematically regarding the top end's functions. I've used these programs since they were DOS. I won't agree with the statement on diminished returns on lifts above .450". The lift itself is fairly useless, but the benefit is cylinder fill from more off the seat time. I've seen small changes like 10* more @ .050", +.030" lift, Tighter LSA, +.5 static comp., a better header and exhaust system along with mild porting get a high 15 second tank into the mid 12's. None of which likely would have much effect without the porting. I hope this wasn't too far off on a tangent.
I enjoy reading your thoughts. I agree with most of what you say, as there are variances of opinions on certain things, but we can all agree on the math at least. The Buick 350 head does have diminished returns on lifts above .450. Not necessarily so with other engine designs, so I agree with this point in that regard. More off the seat time is what the stock cam (or any other asymmetric design) cam is all about, and is why it does as well as it does with such a low lift--particularly with the Buick 350 head design, which is optimized below .400 lift to begin with. When 95% (or more) of the head flow exists below .400 lift, you can see why adding .200 more lift wouldn't really add much, though it will increase the off-seat time, which is really the only reason why it improves performance at all when considering this specific head design. A custom cam I recently created to add performance to a relatively stock engine and stock environment (car included) with a lope and great off-idle power up to 5500 RPM, showed that this cam only gained 7 hp and 6 ft. lbs. when going from .400 lift to .441/.446 lift, while VE wasn't improved much at all. This was a symmetric lobe, so the off-seat time was increased some, but not enough to really make a noticeable difference in performance. Incidentally, the engine produced 399 ft. lbs. and 349 hp with .441/.446 lift, has identical characteristics (and power) to the TA 212-350 cam, but has a 200 RPM lower powerband on peak tq and hp, with a flatter powerband at lower RPM, showing about 360-370 ft. lbs @2000 RPM. The .400/.400 version lost 6 ft. lbs. and 7 hp (393 ft. lbs/342 hp), but made the cam much gentler on the valvetrain. I still haven't decided which is the better tradeoff. Maybe I'll move lift to somewhere in the middle ground and get a balance between the two. Everything is relative, but I specialize in the Buick 350 and my comments reflect this. Thanks for your thoughts! Gary P.S.--this cam's ideal compression is 9.5:1 static, used the TA intake and small tube headers to get those numbers. It would suit a larger, heavier car and still give a nice lope (which people seem to want, so it's not 'boring'). Cam specs are: 272/284 @.006 with 60* overlap, 216/228 @.050 with 4* overlap, 109 LSA/106 ICL. With .441/.446 lift produced 399 ft. lbs. and 349 hp. Heads were standard 1975+ 1.875/1.55 valve size with mild cleanup yielding 205/139 CFM @.400 flow. Stock heads are 198/130, so a gain of 7 CFM intake and 9 CFM exhaust over stock. Peak torque sits at 3900 RPM and peak hp at 5000 RPM. Super wide torque band stretching down to 2000 RPM with excellent low end as well, so a stock or 2000 stall is really all that's needed. Suitable for larger cars that want a lopey idle and not lose low end. Even with polished exhaust manifolds and the use of an "X" pipe, would still be good for this combination with the scavenging benefit of the "X" pipe and 12* exhaust emphasis (same as TA 212-350), but with a slightly lower powerband and longer dynamic stroke for better low end torque. Overlap @.050 is same as TA 212-350 so should idle with a similar lope, but has 2* less overlap @.006 so slightly better intake vacuum and street manners. Even with the .441/.446 lift has the same lifter acceleration rate of 2.38 as the TA 212-350 cam, so should last at least as long as that cam. With .400/.400 lift has a 2.22 ramp rate, so would last longer this way with a trade-off of a few numbers. Lobe intensities are 56* for both intake and exhaust, so the TA Stage 1 springs should be used. If anyone wants to use this cam grind be my guest, just give me credit for its design. :TU:
I'm seeing different potential with the OP's given parameters and questions. "its the hooker 1 3/4 headers 2 1/2 exhaust either stock or the T/A dual plane already have the large valves and will probably do a little work to the bowl I assume its a 108 because most 112 lsa cams are" Add a desire for 10:1, a curiosity for a "level 4" cam (maybe more if a sim supports it) and we're talking a whole different animal. I'd be curious to see wilder cam specs, level 4 (228-242* .485-.512" 108* LSA) and level 5 (240-246* .516-.544" 108* LSA). With some focus on the head porting, I bet this really wakes up. If changing any parameters, I'd play with the head flow with these cams and see where you end up. Replying to Gary, I'm almost succeeding at describing my point. Maybe a more accurate way is to say "more degrees of rotation of mid lift" where the head works better, rather than just "off the seat time". I think we all agree that the lift above that is wasted and serves to keep the lifter in contact. If your target build is 370hp and you are using a 200-230 cfm head, then minor changes in cam specs are only going to move some things around in the torque curve and likely start reducing bottom end. The mild Buick 350 is fairly well matched up as a package. When trying to exceed a starved engine more cam can help, when you aren't tripping over your foot somewhere else. As far as behavior "on a Buick 350" or "any other type of engine", the way I view that is basically [that] head's characteristics on a short block of a specific bore/stroke/dynamic piston speed... package. Being that the Buick 350 has a very high swirl head that works well in it's stock form for its range/duty, when you PORT it you change the main characteristic that causes it to behave the way it does. They very mixture motion (swirl) that makes it shine in a limited range has a balance point and is an excellent limiter. It is reduced somewhat for more raw cfm and a different limiting velocity based on CSA. THAT is what determines your power peaks, and sets the stage for the build up of components around it. A proverbial wolf in sheep's clothing. Not to seem frustrated, but I see a lot of "guess the power" threads without head #'s (which only go so far regarding CFM's). [not this thread] People seem dead set on determining their componentry, but not dead set on their goals which requires some commitment to the heads. More than "maybe some pocket porting". It's not terribly difficult to say, "This is what I want" and then do what it takes to make that happen. :beer
Just read over your response, and am formulating a response of my own, but having just woke up and sipping my favorite coffee (Starbucks House blend ground from whole beans) and listening to Nine Inch Nails, my body reminds me of the biological needs surrounding such events, and so soon I shall sit and think of the response I shall formulate...lol Anyway, good stuff. Seems you and I think along the same lines in many areas. What you say here I've said too in the past on other posts (more or less). Response forthcoming. Gary
The original cam suggestion I posted earlier was the real suggestion to the OP; the second cam suggestion was more of a tangent with another combination that I hear (read) frequently here on the forums. There is no real magic going on here, it's simply matching parts to parts that compliment each other and work well together so as to result in a final package that performs as efficiently as possible. I believe you succeeded in describing your point, whether you describe it as 'off the seat time' or 'more degrees of rotation mid lift' paints the same picture for me. Moving on, we can see that the Buick 350 head flows best between .200 and .400 lifts, so anything that keeps the valve open for longer periods of time within this spectrum is the goal when maximizing power. My previous statement claiming that anything over .450 begins to approach the 'diminished returns' realm is accurate when realizing camshaft lifts between .400 and .450 lifts provide more time in the .200-.400 spectrum than any lift beyond that, even though greater lift will equal wider duration within that spectrum to a point, the values of gain diminish greatly after .450 lift, hence my statement. Cams tend to increase lift when increasing duration, and as habit would have it, tend to follow patterns more familiar with other engine designs because that's what works for them. The Buick 350 head is a different animal, as you described earlier with the low lift swirl effect that is its strongsuit. While this design will maximize power within its intended engineering design (as I have spoken of in the past on several occasions for anyone who's followed my posts--haha, right?), tends to be the limiting factor when increasing flow and lift beyond this point (which the aluminum heads should change--we'll see). Even so, fully ported iron heads STILL fall on its face after .400 lift, only gaining 20 CFM from .400 to .600, which is peanuts when looking at gains below .400. On such heads, you could gain more with .500-.600 lifts than you would on untouched or mildly ported heads, but the gains are still minimal when considering the gains at lower lifts. You will only gain so much time 'at mid lift' when increasing lift without widening up the duration considerably, which of course creates a whole other monster with a much higher power band. Increasing lift without increasing duration creates sharper peaks on the lobes, which succeeds more in shortening the camshaft's life than any real performance gain. Perhaps it is I who has not succeeded in describing my point? The previous cam I suggested I also suggest using as a roller grind with .480 lift; otherwise keep lifts around .450. This is only my recommendation; people can do what they want with their money, that's up to them. With 230 CFM heads the cam shows a 388 hp average peak power and 406 or so ft. lbs. This is pretty decent I think for a cam that behaves mildly on the street, and you won't really gain much one way or the other with minor tweaking. I agree though and share your frustration when reading vague figures with ancillary track runs or dyno pulls that try to advertise the benefits of one thing over the other without taking everything else into consideration, which is why I post both .050 and .006 graphs with my findings. While this is far from 'everything taken into consideration', at least gives more information to be taken into account. I think people are dead set on their componentry because it becomes a psychologically satisfying number, not realizing there are an infinitesimal myriad of variables, though we can agree that we stay within a majority zone (sweet spot) of atomic structures defining what things 'are'.
Excellent response! The coffee does help things, doesn't it? I thought your selection was well thought out, I was just pointing out how things change when you take it further, with a more specific target in mind and the build following around that. There are some 350 build threads in here with the heads showing impressive results, maybe beyond the norm of a "pocket port" but certainly not unreachable. If that were a focus, it would be a game changer. One misunderstanding people have is a strong belief that the cam infinitely controls the powerband. The different ways people understand the tech might be why there are such opposing schools of thought. It was much simpler to for me to understand how the cam specs influence the powerband with the acceptance that the intake tract sets the stage, and the cam's events are influencing things based on the rest of the componentry and how they relate to the whole package. I guess I can't say that my way is the right way, it's just how i learned it. I haven't seen where the power peaks were math'ed out based on valve events, but rather through the head's attributes, with a close eye on maintaining pressure differential if running aggressive (overcam) amongst other things. The cam (again, using head calcs) seems to determine the VE and cylinder pressure curve, more so when the componentry is considered. Rather than believing the cam simply raises the rpm range up, it doesn't. It just kills bottom end quickly (later trapped compression, risk of delta P loss) without raising peak hp, (intake tract choking out). Basically the wrong cam misses the mark. I do see and agree with your point regarding where the best efficiency and most gains are made, if left mild. I disagree with "little gains being made" overall to the power curve by pushing the package a bit further. If that's the case, there are other limiters being overlooked, and a skilled engine builder doesn't have to throw up their hands and accept some of the limitations, because after all "it's a Buick". [Yes, there ARE limitations to the castings] The Buick becomes a different animal because the head porter changes the characteristics that define it's behavior. I also have a lifetime's pile of builds that have proven their longevity, despite the valid theory that a wilder valvetrain shortens life. It's all relative. Is the owner really going to drive it 100k miles before diving back in? It CAN go a long ways with careful planning. Industrial and fleet engines with mild valvetrain might see 700k+ life, is that the life you are going for? I know for a fact that a BBC (with stock base circle) flat tappet hyd. cam can go 140k+ with an L-88 spring, spring changed at the 1/2 way mark. This is in the .540-.560" lift range. How would that profile compare to the thread subjects previously offered here? Genuine question, not confrontational. Ignoring the benefit of the wheel on the roller lifter and only looking at the off the seat curve, what you are describing as "not doing much good because there are no further gains in airflow above x lift" is EXACTLY why the aggressive roller cam profiles shine! That's also how more cam matched to a well ported head would shine. Porting the heads widens the powerband on both sides, when compared to inadequate head flow. It might put the torque peak slightly higher because of CSA, but it can also raise and flatten the range below it because of improved velocity and efficiency. Well ported heads noticeably shine at part throttle, and below peak torque. When you get that working right you still see more torque than a stock engine, even at relatively low rpms. Maybe not at 1200 rpms, but hopefully matched to the converter at a slightly higher rpm. I don't see any disadvantage. The same strategy for airflow and camming I'm describing is being used successfully on much wilder platforms in racing situations where there are still architectural rules limiting things. It might not be as low hanging fruit, but the engine still responds. Otherwise, I think you are 100% on point. Back to the OP's questions. It isn't that I have different views, it's that I see it being just as easy to get the head where it needs to be and go for a wilder build rather than tone the engine down with lower compression and milder components. If there are any 350's that can breathe to 6200+ rpms or so, then certainly they can be built in mind for streetable use.
Good stuff. I've said before that opening up other areas around the camshaft (intake, heads, exhaust) will affect the powerband using the same camshaft...I've done some writeups on the stock cam describing this very thing before, and how you can gain power without changing cams. Example: a Buick 350-2 using a large base Rochester 2g shows peak torque a 2400 RPM, but putting on a Qjet, freer flowing intake, heads, and small tube headers will increase peak torque to 3750 RPM! This is quite a jump, and all using the exact same camshaft. Horsepower peaks go from 4400 RPM with the 2g to 5000 RPM and increased by over 50 hp. To reaffirm what you've said, torque below this peak is also wide and increased beyond what the exhaust manifolds can provide, as long as there is no "X" pipe involved. Put in an "X" pipe, and it mimics headers (up to a point) with scavenging, raising poweband and increasing the numbers across the board. All this done using the same Federal Mogul CS647 camshaft! Other cams would be similarly affected, perhaps more or less so depending on design. Getting back to the longevity issue with lift--as you and I both said, it's relative. There's no yardstick per se to determine how long something will last, based on user maintenance, defects, usage, etc., it's all been pretty much just a 'guestimate'. I don't think anyone here really knows for sure just how long something will last, but we can all agree that more intense, generally speaking, usually ends up with more strain on components which results in shortened lifespan. Not to say a stock cam couldn't wear out in 50,000 miles, or a performance cam couldn't last 150,000 miles. There will always be exceptions to the 'rule' if there is such a thing. My main point was to keep intensities on lobes within a reasonable area (and even THAT is relative!), based on the material used and design. Greater lift, as long as it's accompanied with adequate duration, keeps lifter acceleration rate within a reasonable range, and can even be gentle, and as was said before--is relative. I see camshaft designs where performance is always the goal, but more often than not at the expense of gentleness on the valvetrain. It is also worth reiterating that roller cams do in fact increase the time spent in-between seat and max lift, making increased lift on those even less necessary than with flat tappet cams. Call me stingy if you will, but longevity is more important to me than performance. If there is any way I can maximize this without sacrificing performance, then I will, but not at its expense. When people spend good money on products and services, they want to know their money was well spent and will last as a quality product should. It's always nice exchanging dialogue with you. Others here can read this too and maybe learn a thing or two! Or maybe it will spark questions or ideas, keeping things lively and productive. Gary
I just wanted to pop in and thank you for your time and input into my projects! Keep up the great work
