I agree with you, many of the things being done today havbe been done in one form or fashion over the last 100 years or so. People thought hydraulic rollers were the newest and coolest thing in the late 80's. I had seen them in a 1927 Cadillac motor.

So, I guess new isn't an apt term, perhaps re-discovery. Or, perhaps application of an existing design to a new or different platform.

I would agree, some of it is marketing hype and B.S. The big thing is simply getting educated if you are interested in this sort of thing. The dig deal is to get the idea in our head to build it as a system, the biggest of everything thrown together won't necesarily make any more power than carefully matched and selected components. Folks need to realize that throwing more lobe at something isn't necessarily going to always make you more power.

 

The law of averages...if your going to give it more of something. . .then something else has to get smaller. Now, with that said, take a stock 5.3 liter engine. If you put more effecient heads on the engine, do you really need a bigger cam.

Cstraub

 

I agree and it makes sense and probably why we keep smoking #7
I believe 2 things might be happening detonation from lean condition to much air dump from manifold design might have to check with a temp probe and run richer to protect it (#7) maybe from all the oil ingested
from the pcv.
I think it would be interesting to see if it could be richened without making the whole engine pig rich.
Some wild ideas
Bigger injector there ,bigger cam lobe maybe duration (I don't know enough)
Smaller runner on the intake ,maybe something as simple as spark plug.
if we could get it fixed without killing timing and adding fuel to kill performance.
It might be of some interest.
This is just my ideas and opinions ,with absolutely no research or any facts to back it up .

 

Who's to say all cylinders should be identical with respect to airflow and shape of torque/power curves?

Sometimes it's very difficult to get all of them pulling their equal share of the load due to physical restraints like head port shape or length, manifold runner size, length and configuration, mixture distribution (carbs), or even header primary pipe length due to chassis interference. We try to equalize, but is that necessarily the optimum?

If you goals are for most area under the (torque) curve (AUC) (and/or hp curve for that matter) in the rpm range you run the engine at WOT, perhaps some of the cylinders should be setup to do best at one rpm and others at another rpm. That might possibly give more AUC.

If that is a goal, then pick the cylinders with say the best manifold/port combination and tune those for say high rpm peak. Of course total length is very important, but so is flow and port volume.

The other cylinders might work better at a different rpm with smaller, higher velocity ports and even different exhaust primary pipe diameter and length. That might fill in a "hole" in the curve and help the total AUC.

It probably goes without saying that these different combinations might need different valve timing and maybe different ignition timing and different amount of fuel. Maybe not 16 different lobes, however.

All of these things have been done in the past, and probably the present, but not necessarily on the same engine. Different ingnition timing for each cylinder is easy with some of the digital "spark boxes". Previously it took distributor cams or reluctors with uneven spacing, but that's been done, I'm quite sure. The biggy is figuring out just what each cylinder needs. That's where advances in technology make it easier to calculate and measure as well as control. Things like CNC cam grinders like Okuma's newest store the lobes digitially in memory and can be programmed to grind any profile on any lobe at any radial location. Clay Smith would love it!

I am in strong agreement that a camshaft should be "combination specific" as Cstraub said. Aren't OEM cams exactly that? Of course they have lots of things to consider other than max power in a narrow rpm band. I know some of the OEM engineers hate it that they can't give us all the power available because of all the emissions, economy, durability and cost targets they have to hit. The potential is in there; we're left to dig it out for our "off-road" engines where we are more tolerant of emissions, economy, part cost and durability limtations.

My $.02

 

This was a long but awsome read. After reading all this , the happier I am with my single pattern c1 cam. My heads flow only 257@.600 with great low and midlift but the exh flow 219@ .600 and I have Mac Headers. My car is full weight and heavy and I only have around 10.4 /1 compression with 241 castings shaved .015 off of them. For my raceweight and whole set up , I cant be happier with my c1 cam as it just works great with my whole combo. WIth the way my heads flow,It seems some would like a reverse split over a conventional split right? THe single pattern seems to work well though.
I chose this cam just from what others have done with it as I knew nothing about cams when I built my engine and wanted to stay streetable. With what I have , is my way of thinking on track to stick with say a single pattern if I chose to go a little bigger (226/226 xe lobe design) later?

 

JROD:

Incredible HIGH TECH scientific cam thread you have started here. AWESOME THREAD no doubt!

Can all you cam experts here recommend an awesome aggressive custom cam for my 03 z06 to compliment my stock LS6 heads, 4.10GEARS and all exhaust bolt ons including long tube headers?

My z06 is my daily dry weather driver and i don't want to spin it past 6700. Also, the car will see only very limited track use but i want to make KILLER power throughout the entire rpm band, as the car is driven the most between 2400 and 5000 rpms on the street!

THANKS

 

On a V-8, you can't have every cylinder the same, look at EGT's. There are variables. I believe though you can get each cylinder what it needs. Now the old days with asymetricals stuff was more of a challange with runner lengths different sizes and all. So to get each cylinder optimized was a challenge and really only done by the top % of engine builders.
With todays technology and symetrical designs it is a little easier but still takes some work.
Cams were a hobby of mine, something I tinkered with in calculations. I soon found if you made power for an engine builder you could sell him everything you had. This is why I am such an advocate of combination specific grinding. If you do it right the first time, then you don't have to do it again. Might be bad for business according to some, but hey my customers are happy.

Pro Stock posted some questions that would be good to address and I would like to be part of it but right now I have got to many irons in the fire before the holidays. . .along with our new oil pan design we are swamped. I will check in on this thread.

I will post this simple thought though, one I used on the www.corral.net. Cost of custom cam:
Shelf cam $300 makes 30HP more cost per HP $10
Semi Custom (application specific) $399 makes 45 HP cost per HP $8.86

Custom (combination specific) $399 makes
60HP more cost per HP $6.65

This is a generalization, but I have had documented cases of a true custom cam making 100HP more then the other.
So if you are conservative or on a budget, then you need to look at cost per HP.
And before it is asked, I do not grind for individuals. I work with engine builders only. No offense but those are my rules.

Cstraub

 

Nobody has had any experience with number 7 self distructing.
Wonder what could be done.
EVAC the PCV through the exhaust
How can we fatten it up
Is it an easy fix or an engineering nightmare?
John

 

% and 7 die on an SBC with a big load of nitrous for a couple of reasons. The firing order has a lot to do with it, and the fact that the cylinders get a hot spot because of the layout of the intake /exhaust ports. One thing that is sometimes done is to swap the firing order in one of several ways. Th eother way as I stated was to pull timing out of the affected cylinder, or de-tune to keep the one cylinder alive. I simply used this as an example of designing the motor as a system, and possible implication of tuning individual cylinders in both cam and timing.

 

What about running a cooler plug in the # 7?

 

I wonder if any of the tuners have done any temp testing on the headers when doing a tune.
It would take a dyno ,engine dyno would be best,
Forged pistons probably hides the fact some detonation is going on with #7
With a leaner AFR .An older ls1 would be best to check this with a nice pcv carboned up engine.
Safe AFR 'S could be set.
Just opinions , but I'l bet GM has the answer,run pig rich?

 

J-Rod and other geeks:

I haven't read it all yet, but this looks like promising background information:

ValveEvents

Search back up the tree - there are other interesting things.

 

I am in the process of reading it. Lots of good info on that site on lots of stuff.

 

Plenty of good data on this thread, if you take the time to sift through it. As many people have pointed out, one of the important takeaways is that the usual cam metrics - duration, lsa, icl - are really just shorthand ways to describe the GEOMETRY of cams. The engine doesn't actually give a s**t about these numbers directly - it cares about valve open/close events mostly, as well as area under the flow curves during max velocity flows. One point that should not be missed - many of the important events from the engine's perspective, such as exhaust blowdown, scavenging during overlap, and intake inertial ram tuning, occur at very low valve lifts (below .100 in a street motor). How many head vendors do you see advertise flow numbers at .025, .050, .100? Yet the ability to flow at those lifts can be as important - even more important - than small variations of flow numbers at max lift.

One other reference source to read if you get a chance: Desktop Dynos by Larry Atherton. Written by the authors of Desktop Dyno, it contains a lot of very well written info about how internal combustion engines actually make power, particularly from the gas dynamic perspective.

 

Did you find the SAE papers (the MAF one in particular)?

 

I am still d/l'ing and reading. I will look keep an eye out for any of the SAE papers. Good stuff, and thanks for the link.

 

Im trying to understand why a later EVO (more closely matched to IVC) is better. Take the two cams below (which i have calculated should both peak at 6400RPM) :-

230/228 110LCA 108ICL

IVO: 31.5 7 -32.5
IVC: 67.5 43 3.5
EVO: 72.5 46 4.5
EVC: 28.5 2 -39.5
O/L: 60 9 -72

230/228 108LCA 108ICL

IVO: 31.5 7 -32.5
IVC: 67.5 43 3.5
EVO: 68.5 42 0.5
EVC: 32.5 6 -35.5
O/L: 64 13 -68


I would think that the 2nd cam would not take as much advantage of blowdown as cam 1, but would have benifit of more overlap. Is this a tradeoff between the two? And which one of these would make more power and have better low-down torque, smoother idle and drivability?

 

Hands down the bes thread I have ever read.

 

There was a gentleman who was going to test 93ponys cams earlier in this thread (page 1-4) with I believe a Corvette..

Did you ever get the cam in and dyno and run it at the track?

I saw the tweaked 220 cam results, and I have to say.. thats not too darned shabby.. I've been thinking of swapping out my cam, and would love to see how some more of 93ponys cams have performed since a few months have passed.

Thanks,

 

The cam that was suppose to be tested was delivered, but never used. The owner opted for a stroker & sold the old motor with the cam... The new owner of the motor/cam opted to not use the cam & instead installed a much larger cam then the C1 & has dynoed 430RW through a solid axle I believe. I assume my custom is sitting on a shelf somewhere collecting dust.

I recently installed another one of my customs into a 2000 WS6.
The setup:
Stock heads (non-241)
Pacesetter longtubes
Pacesetter off-road Y
Loudmouth Catback
Lid of some sort
ZO6 mass air
Linginfelter Aluminum intake un-ported
Comp 918 springs & pushrods
Stock Rocker arms
226/224 110LSA cam

The results were much lower then I expected at 381/364 SAE.
The stock clutch may not have been holding on the dyno as it sticks to the floor on the street. There also may be issues with excessive lifter preload (.125+) hanging the valves open at RPM. & I'm not too fond of a heat-soaked intake...
The owner has not gotten any track time with it. But it does pull harder then all but the fastest (heads & cam) LS1's around here.