Designing Camshafts

frenchyd said:

In reply to mke :

 I think you are right because boost can make up for compression. ( I think).?

  But with E85  I thought if carbureted I could advance the timing and be ahead.     
    Remembering they both have the same net power. 

You can advance the timing with higher octane....but without air Jesus Christ himself can't make hp, we talked about this already.  

I think the porsche turbos were right around 8:1.  

frenchyd said:

In reply to mke :

 I think you are right because boost can make up for compression. ( I think).?

 

You think?  I'm sorry but this is the problem.  Have you done any math?  Do you know what to expect raising the CR by 1?  Do you know what to expect by running your turbos at 14 psi?  These things aren't engine dependent.  These are good rules of thumb that be applied to any engine.

Nah run 10psi and e85, straight exhaust. It should be okay. 

In reply to yupididit :

the HE flow numbers

Race porting

I think the yellow line is nonsense but here's more measured data for ported heads, it says flat which ever that is.  The blue is fitted with clearly WAY too small ITBs, red is head only and green I guess is some CFD modeling the guy was doing and showing it matched the real port.

Efi and e85 we use 10-11:1 comp and some big boost. I would rather high comp low boost than low comp high boost. E85 won't usually end up knock limited, usually just break things from hp. 

In reply to mke :

I fully understand the need for flow numbers.  That's why I got them in the first place.  To get actual numbers after I did my porting I had it actually flow benched. 
   Since then I've found what I did wrong.  I had simply opened everything up. Basically removed the throat.  I now understand that was wrong.  What I did in the entry to the port I think is right. However once going into the throat clearly I need to reshape that throat. 

In reply to mke :

So looking at those numbers I'm seeing an engine that won't really go over 400 hp without boost.  Am I wrong?

In reply to Paul_VR6 (Forum Supporter) :

I would agree if the flow was fixed....but if its giving up a bunch of flow I'm not convinced its a low boost/high boost question..... but I'm not sure how real the flow difference is either as base numbers are hard to find , at least in the 15 minutes I gave it.  Its really hard without real data.

Stampie said:

In reply to mke :

So looking at those numbers I'm seeing an engine that won't really go over 400 hp without boost.  Am I wrong?

Stock HE head, at 141....it take about 4 CFM@28" per hp, so 35hp/cyl? 12 cyl gets you 423 with headers, intake , matched cam maybe?  Is that what you're thinking?  I'm not sure what the other heads do stock.

Ported and race preped the flow and results I saw are up over 700 if they are to be believed but that seems about right.  My 156@10" is like 270@28" so not a lot higher than what the Jag guys are getting and 800 is a conservative estimate for mine I think.

mke said:

This is really 2 builds.  A challenge  build where cost is king. You can't really even afford gaskets so find a running engine and use it.

Then a vintage build where if you want to actually compete cost is no object...and it ain't so easy to go from 300 to 600hp and I'm reading 750 is probably where you need to be if winning is of interest....so the money must flow. This sure seems like a whole different engine....and whole different rest of the car too honestly.

Oh there is no way I'll be at the pointy end of the vintage field. I'm too old, too fat, and too poor. . The big advantage for the challenge  that carries  over to vintage is the weight loss doesn't cost anything. ( in fact it generates trading revenue).  Yes, the Challenge   engine will be stock except for the twin turbo's.  And the baffles I'll put in the oil pan. ( they'll just be fabricated from scrap metal). 
    Turbo's aren't allowed in vintage but they aren't budget limited either( well except for what a semi retired guy can afford to spend). .  
I know what to do regarding handling and brakes for Vintage. The big expense will be the dry sump.  And the rest of what I need to spend  to get the V12 up to the field's level of power. 

yupididit said:

Nah run 10psi and e85, straight exhaust. It should be okay. 

 I was thinking 12 psi. E85. ( assuming temps @150 f or less ). If above that I'll add WW fluid.   The reality is I might need less back pressure which means bigger pipes than  2&1/2 tailpipes and megaphone 

mke said:

the HE flow numbers

Notice they don't mention which valves they are using, stock intake is something like 41 mm while you can get 47 mm  that's pre HE or Flathead.  And the same for the exhaust side.   The one thing I do remember about the pre HE head is the percentage of flow on the exhaust to the intake was way past the 80% number.  
So basically I'll focus on the intake side. 

Stampie said:

In reply to mke :

So looking at those numbers I'm seeing an engine that won't really go over 400 hp without boost.  Am I wrong?

In the 1980's Group 44 was running 750 hp without boost.  And TWR was making 500 hp  using the stock intake and cast iron exhaust manifolds.   Latter version like Lister were over 800 horsepower still normally aspirated. 
     Everybody  fails to understand the advantage the heron head has over  a normal combustion chamber.   
      A regular combustion chamber the flow leaves the port and needs to go up and over the combustion chamber to get to the cylinder walls and fill the cylinder.  
     Each time that flow changes direction flow is lost. 
 A heron head once flow leaves the valve it's got a straight shot out to all the cylinder walls the combustion chamber is in the piston which is moving away

   A 4 valve head has an advantage over a heron head but a heron head has an advantage over a regular combustion chamber in head 

The 12v heads we use flow about 150cfm at 28" (39mm intake valves) and we can make 65whp per hole on pump gas about 11 ways from sideways and 100whp per hole on e85 at higher boost but all else equal. Can make more power on e85 with dropped compression but seems to stress things out more than high comp lower boost.

This thing will make plenty of power even just cobbling together the parts, not even making any sort of good choices.

I've been watching Calvin Nelson's U Tube  channel  where he took a  stock 6 cylinder engine  with 175,000 miles on it and made 824 wheel horsepower on the chassis dyno  

   They also mentioned they were making high 800 horsepower on a drag pass with this engine  but don't have the data to back that up   So they are satisfied to claim 824  

      At one point he accidentally gave it 40 pounds of boost.   The next run he was at  the 824 wheel horsepower number. The final pull he added advance and that's when the stock rod decided to escape the confines of the block. 
   Doing the autopsy the bores weren't scuffed  or any indication the rings were bad.  Top Ring gap was .019-.020   Main and rod bearings were all good.  

      Did the 40 pounds of boost bend the rods?   Or did the second pull at 800+ horsepower  kill them?   Who cares?  
     800+ horsepower on a near stock. ( reground camshaft)  head never off.  Impressive.  
        Anyway I've watched him develop those engines. 4200 Atlas.  And learned much of what I used to think was absolutely required isn't. 
   He started out with a smaller turbo and kept going bigger and bigger. 
 Oh by the way he's gone in the 9's @150 mph with that engine. 

mke said:

Back to cams....valve lift is tied to the head flow curve.  Here's mine (@10" h2o), there is little  gain after about 0.375 on the intake or really 0.250 on the exhaust

So the job of the cam is to get the valve open to the 0.375/0.250 as quickly as possible so the valve spends as much of the duration time near its max flow.   The lobes I chose look like this with stock and another option on there to compare

They open further than needed but that was the easiest way to get quickly to max flow.  another option is a flatter profile on top that limits max lift while keeping the ramps about the same.  

Now look at the stock intake flow....completely flat above 0.250 lift.  The factory cams open the valves to .305 so well past where lift stops helping....almost like the heads and cams where made for each other.  

Designing the cam needs to start with having the head flow data.  There is no other way and this is what any cam grinder will ask for.  There is really no point in throwing around cam numbers until you get the flow numbers.

mke. That sure was informative. Especially what you said about  intake flow above .375    But the reason you went over was to start opening the intake earlier in order to get the flow going.  That was a light bulb on moment.  
       I don't have to chase a pushrod engines .700+ lift. Just get the air going  enough to fill the port. 
  Hopefully you've read what I wrote about heron heads. The advantage they have over a combustion chamber in head. 
  Putting 2+ 2 together  am I going to be better off with a top 1/2 of a ballon shaped cam lobe  over a lobe that has straighter sides?  
   Oops remembering what you said about opening the valve as quickly as possible. I just answered my own question with your help. 

In reply to Paul_VR6 (Forum Supporter) :

The stock 308/TR numbers are similar flow (maybe 158@28")  but they lowish  CR  (9 on the 2V, 8.6 on 4V) ...60hp/cyl is a basic bolt-on at 10-12 psi, generally no intercooler.  With coolers 75-80/cyl on pump gas at 20-25psi, on my engine the only internal change was valve springs.  I think maybe the amount of intercooler need is maybe the many change CR causes I've seen, a lot of guys bump to 10:1 or to help to bottom end a bit....but the total number of boosted 308s/TRs is quite low so a maybe not helpful data set and I have no E85 data at all for these....but making 500hp from a 3.0 liter on pump gas is stupid easy so yeah, from a similar 5.5liter should require very little effort.

Looking at the HE higher compression head the combustion chamber is very weird and that scares me a bit.  I see what they were trying to do but.....

Seems like you are more efficicent as all my numbers are with IC, but my numbers are also whp so could be close-ish. We are at those power levels at 20psi pump and 30psi e85, but turbo choice, etc can push them a lot higher (have some race cars at 900+ on stock bottoms with just arp bolts and studs, springs and cams  but with turbos that are almost unuseable most of the time)

In reply to Paul_VR6 (Forum Supporter) :

Mine were crank numbers ....so WELL below your numbers

....a 308 is about 18% drop crank to wheel

mke said:

In reply to Paul_VR6 (Forum Supporter) :

The stock 308/TR numbers are similar flow (maybe 158@28")  but they lowish  CR  (9 on the 2V, 8.6 on 4V) ...60hp/cyl is a basic bolt-on at 10-12 psi, generally no intercooler.  With coolers 75-80/cyl on pump gas at 20-25psi, on my engine the only internal change was valve springs.  I think maybe the amount of intercooler need is maybe the many change CR causes I've seen, a lot of guys bump to 10:1 or to help to bottom end a bit....but the total number of boosted 308s/TRs is quite low so a maybe not helpful data set and I have no E85 data at all for these....but making 500hp from a 3.0 liter on pump gas is stupid easy so yeah, from a similar 5.5liter should require very little effort.

Looking at the HE higher compression head the combustion chamber is very weird and that scares me a bit.  I see what they were trying to do but.....

 

That was basically the 1920's era Buick fireball head designed to run lean  and save gas.  One of the side effects  was it was clean running.  ( pollution wise). 
     In the mid 1970's Manufacturers we're warned about coming pollution limits by California. Which at  the time scared the heck out of Jaguar. They had no idea how to meet the proposed rule. That market exceeded more than 50% of Jaguar's sales.  They happened on The May head ( named the fireball head ) found it met the new requirements 

   Chrysler had been trying for something like that as well. 

Paul_VR6 (Forum Supporter) said:

Seems like you are more efficicent as all my numbers are with IC, but my numbers are also whp so could be close-ish. We are at those power levels at 20psi pump and 30psi e85, but turbo choice, etc can push them a lot higher (have some race cars at 900+ on stock bottoms with just arp bolts and studs, springs and cams  but with turbos that are almost unuseable most of the time)

That's part of the reason I selected the turbo I did.  I'm not racing a dyno, I not only need to do well in the drag race but also in the autocross. If it was just 1/4 racing. I'd gone bigger.     
      Calvin Nelson made 824 wheel horsepower  on the chassis Dyno using an engine with 175,000 miles on it without any up grades or even opening up the engine except to put a pair of reground camshafts. So depending on what engine it is a lot of that stuff isn't needed. 

frenchyd said:

Stampie said:

In reply to mke :

So looking at those numbers I'm seeing an engine that won't really go over 400 hp without boost.  Am I wrong?

In the 1980's Group 44 was running 750 hp without boost.  And TWR was making 500 hp  using the stock intake and cast iron exhaust manifolds.   Latter version like Lister were over 800 horsepower still normally aspirated. 
     Everybody  fails to understand the advantage the heron head has over  a normal combustion chamber.   
      A regular combustion chamber the flow leaves the port and needs to go up and over the combustion chamber to get to the cylinder walls and fill the cylinder.  
     Each time that flow changes direction flow is lost. 
 A heron head once flow leaves the valve it's got a straight shot out to all the cylinder walls the combustion chamber is in the piston which is moving away

   A 4 valve head has an advantage over a heron head but a heron head has an advantage over a regular combustion chamber in head 

Is that SAE net or DIN? (to get SAE horsepower from DIN multiply DIN times 1.0139)