Cam design limitations

-
Hey bill i read what you posted about lob separation and duration is this for tuning at idle?
So you can optimize boost.if so wont a higher duration help you out in the higher rpm range and if so have you looked in to the rhoads lifter as they allow you variable duration for better idle and pump up around 3000 rpm.I know this is a slant 6 but i use rhoads lifters in my 440 and i have a long duration cam but i idle very well at 800 rpm.just asking if this might help save you a dollar.

http://www.rhoadslifters.com/Pages/PartNumber.html

I just checked web site they dont list /6 but i would call them any way.

You could be right. I have NO experience with turbo cam design, and am just going by what I am told by a few successful turbo racers who make virtually 500 horsepower from a 225 slant 6. They are all running short (210 degree) duration cams. I get a lot of feedback from a group of Buick Grand National racers who I meet for breakfast at (YAWN) 8 a.m., every Saturday. Three or four of their cars run in the tens (231 cubic inches) and none of their cams have more than 215 degrees duration @ .050"-lift.

So, being the newbie, I kind of have to go with what works for these experienced racers.

The cam in the engine now, is a 210/210 (Bullet) grind, but I have a new Comp cam that is 210/220 that I want to try after I get a baseline with this one.

I'm afraid a "good" cam for a normally-aspirated engine would just blow significant amounts of boost out the exhaust valve during overlap.

But, we'll see; this is just an experiment...


Thanks a lot for your interest and input!!!
 
I think he's just saying "Never Mind". Anyway I think your best option in this case is increasing the rocker ratio if you haven't considered that already. Or go roller, those are the only 'safe' ways to get the rates-of-lift you need. Also I think turbo cams are traditionally dual-pattern with extra lift/duration on the intake side to pack the cylinders better. Heck if it was mine I'd consider just swapping up to 1.6 ratio rockers on the intake side (or even better 1.7/1.6 if they exist for /6), that gives you a dual lift pattern right there.
 
Bill, What is the bore, stroke, valve sizes, and head flow info for your engine? What about the type of turbo you have? I see what they are doing, at least I think I do... But there may be other ways to keep the exhaust from acting against the intake flow. That MM series lobe has a .535 lift at 235° @ .050 so I think it's close. But that is a very fast ramp speed and I would be concerned about the life of it it in a street environment.
A friend of mine races a 232" Chevy and it's turbo'd on methanol. It makes enough steam to run mid nines. I can't tell you how many mods were done to get the engine capable of making that power. Including him paying for lots and lots of camshafts...lol.
 
I think he's just saying "Never Mind". Anyway I think your best option in this case is increasing the rocker ratio if you haven't considered that already. Or go roller, those are the only 'safe' ways to get the rates-of-lift you need. Also I think turbo cams are traditionally dual-pattern with extra lift/duration on the intake side to pack the cylinders better. Heck if it was mine I'd consider just swapping up to 1.6 ratio rockers on the intake side (or even better 1.7/1.6 if they exist for /6), that gives you a dual lift pattern right there.

there are to many headaches with the current company who makes them... not relable and have oiling issues...

slants have a 1.4 ratio stock so a 1.5 or 1.6 is plenty... if they were made lol...

but let me throw this into the mix... i have a Friend, he races drag bikes, mostly old kawi's... he has a 900 triple ( i think) with a turbo and No2... lol really... now he said the trick for a turbo motor is either run alot of lift and no duration or alot of duration and no lift... BUT when running no lift it makes the top end happier cuz it will last longer...

now being i havn't played with a turbo i dont know how you RPM range would if at all be affected but with boost i dont think it would matter...

P.S. he runs 60lbs in the kawi... i have vids of it but he asked me not to post them...
 
I think he's just saying "Never Mind". Anyway I think your best option in this case is increasing the rocker ratio if you haven't considered that already. Or go roller, those are the only 'safe' ways to get the rates-of-lift you need. Also I think turbo cams are traditionally dual-pattern with extra lift/duration on the intake side to pack the cylinders better. Heck if it was mine I'd consider just swapping up to 1.6 ratio rockers on the intake side (or even better 1.7/1.6 if they exist for /6), that gives you a dual lift pattern right there.

Thanks for the "N/M" explanation; I am not cell-phone texting/shorthand savvy... if that's what that was...

Believe me, if 1.6 rockers were available for this engine at a reasonable price and with decent reliability, I would already have a set and wouldn't be wasting your time (as well as others') with this I am investigasting the process of modifying a set of stock ones , myself, but am just getting started on that investigation.

Roller blanks for a slant 6 cam are $1,000.00.... 'nuff sed. We don't need horsepower THAT bad; if we do, we'll just crank up the boost some more.

This is just a hobby/bracket project, will never be street driven, so getting the last tenth out of the engine is not a critical issue at all; just two old guys tryin' to have some fun. That doesn't mean that we're blissfully unaware of certain technical posssibilities available, but we're not knee-jerk about it, like if it were an NHRA class car.

Thanks for your insight and information. It was duly noted, and appreciated.
 
Bill, What is the bore, stroke, valve sizes, and head flow info for your engine? What about the type of turbo you have? I see what they are doing, at least I think I do... But there may be other ways to keep the exhaust from acting against the intake flow. That MM series lobe has a .535 lift at 235° @ .050 so I think it's close. But that is a very fast ramp speed and I would be concerned about the life of it it in a street environment.
A friend of mine races a 232" Chevy and it's turbo'd on methanol. It makes enough steam to run mid nines. I can't tell you how many mods were done to get the engine capable of making that power. Including him paying for lots and lots of camshafts...lol.

Here is a thumbnail sketch of the mechanical specs of our engine:

Block: 1964 225 slant 6
Head: 1964 225 slant 6
Crank: 1964 forged, ground .010"/.010" and balanced

Block modifications: bored .065" (234 cubic inches); no deck cleanup milling necesssary

Cylinder head was bought used off ebay from a guy who found it in a VAN, in Las Vegas. The van was in a junkyard, so he never got any information about it, but it was ported (pretty nice port job, my machinist said) and had 1.74"/1.5" valves installed. It came with a set of stock rocker arms, which we are using.
It's never been flowed...

.024"-thick. shim steel head gasket

The cam is a Bullet flat tappet, and I don't have the card handy, but I'm pretty sure it's a 210/210 @ .050", with .484" lift, ground with 115-degree lobe separation. I put it in 4-degrees retarded to kill some anticipated (hoping for the best!) wheelspinning low end torque. That may have been a mistake; we'll see.

904 Torqueflite with the 2.74 low gear, a full manual reverse pattern valve body and a TurboAction reverse pattern floor shifter ($300.00!!!) damn...
3,000-rpm-stall, "bastard" Hughes torque converter ("bastard" because it has early and late internal components to make it fit the early crank snout and late front pump...)

The head had never been milled, so, with some forged, Wiseco flat top pistons, .167" below the deck. The true (measured with a burette) compression ratio turned out to be very close (VERY close) to 9:1. About right, with the 7-inch K-1 forged rods that went with the pistons, as a "set" kind of.... Wiseco works closely with K-1 and developed this low-drag ring setup piston combination, specifically with the wrist pin set (height-wise,) to work with the long, 198 slant 6 forged rod that K-1 produces.

We filed the ring end gaps to: .020" top,
.024" 2nd.

Blow-thru modified 750 Holley 4150 double pumper with a boost-referenced power valve.

The turbo is a 67 millimeter, Turbonetics, 4-bolt mount unit that came to me from a friend who runs an identical unit on his Grand National Buick (231 cubic inches,) His car runs mid-tens, so he said it should work well on our motor. Our camshafts are very similar in duration and lift.

The header is a 6-into one, 1 5/8", one-off, long tube piece that my partner, Freddie, built. It's nice looking, but I am apprehensuve about the heat that will radiate from those long tubes before the exhaust charge gets to the turbo. Heat is everything to a turbo. I'm sure we'll experiment with a different (shorter) setup, down the road, after we get this monstrosity working... The guy that ceramic coated them said DO NOT wrap this header. He didn't elaborate.

The intake manifold is a long-runner Hurricane from Ausatralia. After the header was built that fits the configuration of that manifold's runners, a very knowwledgable source told me that long runners are very bad for boosted applications and the FIRST thing I need to do, was to get rid of that intake manifold. He was serious, and he's someone who knows what he's talking about, when it comes to turbos.

So, I bought an Offenhauser 4bbl manifold and it didn't come CLOSE to working with that header (runners hit the pipes.)

So, I heard that the Hurricane short runner ($500.00) manifold was a close copy of a Clifford, so I bought a Cliffford. It was better, but still had a considerable amount of interference. We beat the header, and ground the cast runners 'tll we went through to air... still no fit.

I guess we'll start out with the long-runner, for now,:sad7:

We have an oil pan that has had the sump deepened 2.5" and baffles added to prevent oil pump pickup starvation on both acceleration and deceleration.

electric fan
electric water pump

stock oil pump

stock electronic distributor with an MSD 6-AL II (digital)
MSD Blaster coil

Taylor solid core wires

Snowperformance Stage I Boost Cooler meth injector that will be set to start spraying at 3 psi of boost

Walbro 51 psi fuel pump running through 3/8" line to a boost-referenced Mallory regulator set at 6psi for the needles and seats. Two inline fuel filters; one before and one after the pump.

Front mounted intercooler that is rated at 550 hp... Don't think we'll be making more than that... lol!

Sorry this is so logn, but you asked; I probably left something out, but I am a 2-finger typist and am s-l-o-w.... and, I forget...

Thanks for listening!!!8)
 

Attachments

  • js640_scan0043.jpg
    89.6 KB · Views: 165
  • js640_100_3489-2.jpg
    116.3 KB · Views: 147
  • js640_turboside.jpg
    106.9 KB · Views: 162
  • asu0024-2.jpg
    110.1 KB · Views: 176
there are to many headaches with the current company who makes them... not reliable, and have oiling issues...

slants have a 1.4 ratio stock so a 1.5 or 1.6 is plenty... if they were made lol...

but let me throw this into the mix... i have a Friend, he races drag bikes, mostly old kawi's... he has a 900 triple ( i think) with a turbo and No2... lol really... now he said the trick for a turbo motor is either run alot of lift and no duration or alot of duration and no lift... BUT when running no lift it makes the top end happier cuz it will last longer...

now being i havn't played with a turbo i dont know how you RPM range would if at all be affected but with boost i dont think it would matter...

P.S. he runs 60lbs in the kawi... i have vids of it but he asked me not to post them...

MoparKID?

Are you aware that a 900 Kawi triple is a 2-stroke motor? (At least, every one I have seen is... But I haven't seen 'em all.)

Unless I;m dead wrong (ALWAYS a possibility) it doesn't HAVE a camshaft... Maybe it's a different engine...

Ther rpm thing is interesting. Both Ryan and Tom (the two guys I go to with questions, because their engines both run like the hammers of HELL) say taht 5500 is really streching it for these turbo motors. They just don't pull well after that.

So, it's a GOOD THING that their drag racing experience with these cars has shown them to run their best (60-foot, included) with a rear axle ratio of 2.76:1, because with a 5500 rom red line, they'd never make it to the finsh line on a quarter mile strip, with a 4.56 or a 4.88, like the V8 cars usually have.

Another odd bit about turbos... if your turbo /6 car is street driven; it "likes" a hiway gear, for everything. No swapping of third members, PLUS a cheap 8.25" unit is plenty strong, if you're replacing tht pesky (weak) 7.25" in the back.

Insofar as duration goes RE: turbos, my Buick buddies run 231 cubic in V-6's, some of them down into the nines, and they all run durations in the 208-210-degree range; seldom more. Now, I don't know whether what works for a V-6 works necessarily, for an inline six, but if they are virtually the same displacement, I would think so..... what do you think?

So, with such a short-duration cam, the drivability of these 500 HP engines is almost like a stocker.... 'til you mash the loud pedal... LOL!:cheers:

Ed, I asked you in another post where you thought I might get a roller cam, particularly one with the gear in the center. Maybe you didn't see that...

Can you tell me, please? I'd really appreciate it!

Thanks for any information...:profilel:
 
im sorry bill its a 4 cyl not a trip... but it is cammed...

here are the pics of the 70's drag bike and then his 900 turbo...

as for the cam i just called Schneider...
 

Attachments

  • jims 018.JPG
    142.3 KB · Views: 142
  • jims 017.JPG
    138.5 KB · Views: 147
  • jims 015.JPG
    132.3 KB · Views: 147
  • jims 013.JPG
    136.8 KB · Views: 146
  • jims 012.JPG
    129.4 KB · Views: 141
  • jims 011.JPG
    145 KB · Views: 132
  • jims 025.JPG
    112 KB · Views: 129
im sorry bill its a 4 cyl not a trip... but it is cammed...

here are the pics of the 70's drag bike and then his 900 turbo...

as for the cam i just called Schneider...

Thanks for the pix of the turbo bike; NEAT!!! You wouldn't get my arse on the seat of that thing... :angry7: Looks like it could get downright violent IN A HURRY, to me... LOL! Sixty pounds of boost... incredible. We're gonna try to find out what a slant 6 will tolerate... but, we'll probably hafta pull the head and O-Ring it, first... shoulda done that (O-rings) when we had it apart the first time....

20-20 hindsight, you know... Oh well...

I'll give Schneider a call in the morning and see what they say about a roller...

Hope he tells me the same thing he told you!

Thanks for the info!!!!:profilel:
 
Thanks for the pix of the turbo bike; NEAT!!! You wouldn't get my arse on the seat of that thing... :angry7: Looks like it could get downright violent IN A HURRY, to me... LOL! Sixty pounds of boost... incredible. We're gonna try to find out what a slant 6 will tolerate... but, we'll probably hafta pull the head and O-Ring it, first... shoulda done that (O-rings) when we had it apart the first time....

20-20 hindsight, you know... Oh well...

I'll give Schneider a call in the morning and see what they say about a roller...

Hope he tells me the same thing he told you!

Thanks for the info!!!!:profilel:

no problem bill...
 
no problem bill...

Called and had a nice, long conversation with the older of two Mr. Cantrells at Schneider, and he told me that he could deliver a roller cam for $1,000.00-to-$1,100.00, includung the cost of the blank. That's not unreasonable, considering, but it's not in this year's budget.

He's a nice guy, and will get my NEXT camshaft business...

Thanks for the tip, Ed!
 
Bill,
Looking at what you have there in terms of intak and exh... I dont think that header's going to help you with the exception of mounting the turbo Heat is key, as you said, and the length of that thing (and shape) will just pull heat out and slow down the air as it moves closer to the turbo. Not to mention the elasticity and compressability of a gas. You may find the turbo extremly lazy as a result. In regard to the cam... I don't believe basing your decisions on the V6 configuration guys is a good idea simply because their packaging is drastically different and much more efficient. Not to mention the tunable electronics running them. Powerful turbo cars make the most of the exh gasses, and pump the maximum amount of air as a result. An aquaintence's late 90s Mustang street racer has a 370-something" engine with a large single turbo. It idles like a stock mustang, yet runs in the 8s. It's all about the manifolding, turbo sizing, and tuning. Much more so than the cam.
 
Bill,
Looking at what you have there in terms of intak and exh... I dont think that header's going to help you with the exception of mounting the turbo Heat is key, as you said, and the length of that thing (and shape) will just pull heat out and slow down the air as it moves closer to the turbo. Not to mention the elasticity and compressability of a gas. You may find the turbo extremly lazy as a result. In regard to the cam... I don't believe basing your decisions on the V6 configuration guys is a good idea simply because their packaging is drastically different and much more efficient. Not to mention the tunable electronics running them. Powerful turbo cars make the most of the exh gasses, and pump the maximum amount of air as a result. An aquaintence's late 90s Mustang street racer has a 370-something" engine with a large single turbo. It idles like a stock mustang, yet runs in the 8s. It's all about the manifolding, turbo sizing, and tuning. Much more so than the cam.

Thanks, Moper. I am sure you're right. We're novices at this, and are natuarally going to make a few mistakes. We'll try to replace that header with a shorter more direct one with a closer-mounted turbo, and get a short-runner intake to work, in the process.

I do think we need more cam LIFT (not neccarily, duration) so I am on my way to a heat treating facility as we speak, to investigate the possibility of doing something to these miserable 1.35:1 rocker arms to get them to a 1.6 ratio, or somewhere, thereabouts.

I thank you for your time and attention to our little project; we appreciate it!!!:cheers:
 
I like the rocker idea... But as I said, the cam isnt a big deal. The way you build power is push more air in, and keep the cylinder sealed. Which is why the others all end up around the same size. The same cam in a 2.2 Turbo II could make 190hp, or 300 or a lot more. It was all the turbo and electronics. It's not that I dont think there's room to improve, I just think you're concetrating on what's easy (ok, relatively speaking...lol), rather than what needs attention first.
 
I like the rocker idea... But as I said, the cam isnt a big deal. The way you build power is push more air in, and keep the cylinder sealed. Which is why the others all end up around the same size. The same cam in a 2.2 Turbo II could make 190hp, or 300 or a lot more. It was all the turbo and electronics. It's not that I dont think there's room to improve, I just think you're concetrating on what's easy (ok, relatively speaking...lol), rather than what needs attention first.

So, if this were YOUR turbo /6, what would you concentrate on first?

Thanks for your valuable input!
 
My opinion is simple. I believe people overthink camshaft selection by leaps and bounds. There are basic guidelines for forced induction camshaft selection. Usually they are wide LSA, a wide split between intake and exhaust duration and smaller than normal duration @.050" figures. I personally think dropping duration down as far as you're talking about would be a mistake. Some of the figures you have thrown out are lower than some stock camshafts.....not that that really matters. Use what works, but I think you will need more .050" duration than 205*. Any camshaft designed to keep cylinder pressure high with a low SCR is what to look for. You can overthink it till your brain falls out. Just use the guidelines, pick a bumpstick and run with it. Stop makin it so difficult, because it ain't. lol
 
well bill if it were me... and i have very limited turbo time...

the turbo works off of expanding exhaust gases so i would be wrapping the crap out of that header... or sell it and start over...

you need to have the turbo as close to the head as possible to have the gases expanding as much as possible giving more boost...
 
well bill if it were me... and i have very limited turbo time...

the turbo works off of expanding exhaust gases so i would be wrapping the crap out of that header... or sell it and start over...

you need to have the turbo as close to the head as possible to have the gases expanding as much as possible giving more boost...


If what you say is true,how does this setup fit into the factors ?? Just wondering !

http://ststurbo.com/
 
All a turbo is, is a driven fan made to do work. It's about expanding and creating more of an INTAKE charge. A windmill is the same principle. It just does different work. It is a driven fan used to do work, same as a turbo. A turbo just happens to compress the intake charge, being driven off the outgoing exhaust gasses. There are certainly more exhaust gasses because of the added intake charge, but those gasses do not escape until they exit the tail pipe, so in theory, the turbo could be plumed at the tail pipe exit. As long as it has exhaust gasses to drive it, it will do its job. As to whether or not being close to the head makes a difference.....Certainly it would. Because hot gas molecules are bigger than cold ones. That means the hot gasses must flow faster to get through the exhaust since their molecules are expanded. That creates more boost. Since you are cramming more intake charge in, surely more exhaust has to come out. That's beneficial to a turbo since it is powered off of the exhaust. It's not the heat that drives the turbo fan. It's the FLOW. The added heat at the exhaust outlet makes the turbo much more efficient by high spool speeds due to the increased flow from the high heat. Much in the same manor a steam engine operates on the expanding steam from boiling water. A turbo away from the heat will still create boost, but much more poorly than one close to the combustion.

Not sure Bill wanted a turbo discussion. We should try to get it back on track.
 
Appreciate the explanation SS !! My knowledge base is very limited !! The more I read these posts,the more I think maybe I should just keep it simple like me !!
 
I live by the K.I.S.S. rule myself. Turbos and blowers and such are cool but you can spend your whole life trying to figure it out when you couldda been cruisin.
 
Appreciate the explanation SS !! My knowledge base is very limited !! The more I read these posts,the more I think maybe I should just keep it simple like me !!

I have never had a turbocharged ANYTHING, and all I know is what I read in the magazines, read on here, and glean from conversations with my Buick turbo buddies, so I am in the dark, pretty much, too.


Thanks to Tom (Shaker223) and Ryan (turbo66Valiant?), I do a LOT of "Monkey see, monkey do."


But I'm way curious, and hopefully, not too old to learn, at least, enough to put this thing into the tens. If I can't do that with all the help I get, shame on me!:violent1:

I don't know who said it, but I like the saying: "A man's reach should always exceed his grasp."

I'm reaching...
and, having fun.

Thanks for your help... all of you!:profilel:
 
-
Back
Top