Slant Six Forum
https://www.slantsix.org/forum/

Eileen - Camshaft selecting
https://www.slantsix.org/forum/viewtopic.php?t=24148		 Page 1 of 9
Author:  Bren67Cuda904 [ Sat Jul 21, 2007 1:30 pm ]
Post subject:  Eileen - Camshaft selecting
Right now I have a 240 @ 50 with .518 lift.
http://www.renaissanceracing.com/images/CamCard1A.JPG
http://www.renaissanceracing.com/images/CamCard2A.JPG
I don't know the overlap on this cam. (45 ish) Its a little bit of a torque cam more than a high RPM one.

My cranking pressure is about 225psi on all cylinders.
I have to run a 50-50 mix of 93 and 110 octane racing fuel to keep it from pinging at 25* total timing.

My main goal with this cam change is to get off the race fuel, but I don't want to just kill the power also. Off race fuel is first a formost.

Does anyone have some cam suggestions?
I know there was some talk about a group cam buy with different intake and exhaust profiles, but I admit I didn't payattention since at the time I already had a cam bought.

The max lift that my springs will handle is .550 Rockers are 1.5 ratio.
Converter is 2500 stall and rear gear is 3.55.
I know it would be better to have a 3000 plus stall converter, but this is what its got.
I am thinking like a 250-255 duration with 60-64* overlap to bleed some pressure off and .535-.545 lift.
Author:  radarsonwheels [ Sat Jul 21, 2007 6:41 pm ]
Post subject:  definitely not an expert but
It is my understanding that with a high overlap high duration cam you can both increase the rpm where maximum efficiency and scavenging occur, and let some of the pressure of a high static compression ratio out at lower rpm, (losing some low rpm power too!) allowing static ratios in the 11:1 plus range without accompanying high cyl. pressures (and knocking)...

I guess you already know all that? Good luck finding a screamer grind for a little torque motor! I guess as long as you can get it to idle below stall speed you will be ok, maybe a little weak off the jump?

Kevin
Author:  BigBlockBanjo [ Sat Jul 21, 2007 9:27 pm ]
Post subject: 
Just a little something....
Alot of people may already know this, so if I write something wrong, correct me.
A 225 has a long stroke anyway, and you stroked it on top of that. (An 1/8"??)
Anyway, this means it has faster piston velocity than normal/ thus faster cylinder filling. So technically, you want a cam that opens at least at TDC. I don't remember what you did to your head, but if you get that much lift, couldn't it possibly cause turbulance? Just tossing it out there,...
I think you should check this cam out, even though it's right at your coil bind point.
http://www.schneidercams.com
Cam part #:14506 Grind#:292-96F
Specs:
292/296 Adv. Duration
258/262 @ .050
0.550/0.500 lift (minus lash)
Lobe sep.- 108*

Nice specs? I bet it sounds good, and it's unique to having more lift on the intake than exhaust.

Here's a smaller one: Part#14504

Good luck!
BBBanjo
Author:  Charrlie_S [ Sun Jul 22, 2007 5:12 am ]
Post subject: 
Quote:
Anyway, this means it has faster piston velocity than normal/ thus faster cylinder filling. So technically, you want a cam that opens at least at TDC.
BBBanjo
HUH? Any automotive cam, I have ever seen, starts opening well before TDC. Even stock ones.
Author:  Sam Powell [ Sun Jul 22, 2007 5:45 am ]
Post subject: 
Radar is right. Increasing the lift will have little effect on your pressure issue. Increasing the overlap is what does this, and this creates the scavenging effect the exhaust has on the next intake mixture. That 108 is headed in the right direction, and should get you what you want. Modern cam profiles with roller lifters have higher lift with out increasing the duration or ovrlap by virtue of the rapid ramp profile possible with a roller lifter. This allows increase in pressure without increasing compression ratios. When I had my cam ground for turbo use, I specified more lobe seperation as I wanted to avoid blowing the mixture right out the exhaust valve before it could close. I can't remember off the top of my head, what that was, but I think it is 113.

At some point you will want to increase your stall on the converter. You will see a huge improvement from that. That actually seems like the simplest improvement you could make right now.

What about water injection to kill the detonation, and get off that expensive gas? That would pretty cheap compared to what you are thinking of spending elsewhere.

Sam
Author:  Bren67Cuda904 [ Sun Jul 22, 2007 7:45 am ]
Post subject: 
A cam change would be cheaper than the water injection, besides I'd have to refill the water lot more often then the gas tank. I'd have to be spraying with anything more than 1/3-1/2 throttle right now to stop the ping.
I am looking for numbers for a custom ground cam based on what my problems are.
More suggestions please.
Author:  skraecken [ Sun Jul 22, 2007 12:00 pm ]
Post subject: 
This is what I should do; first bigger exhaust 2 1/2" from y-pipe.
A cam with duration around 270 degr, a lift slightly below .500, lobe sep. 110 degr.
If this is totally wrong or not, I would try it.
Author:  emsvitil [ Sun Jul 22, 2007 1:22 pm ]
Post subject:  Retard the existing cam
As a test......

This will have the intake valve closing later reducing the effective compression ratio (which is what you're trying to do with a bigger cam)
Author:  BigBlockBanjo [ Sun Jul 22, 2007 3:08 pm ]
Post subject: 
Quote:
Quote:
Anyway, this means it has faster piston velocity than normal/ thus faster cylinder filling. So technically, you want a cam that opens at least at TDC.
BBBanjo
HUH? Any automotive cam, I have ever seen, starts opening well before TDC. Even stock ones.
Charrlie, I must have shorted out between my brain & the key board. :oops:
I meant to write down: he needs a cam that is "well on it's way" to the top of the lobe by the time he reaches TDC./ He needs a high-velocity "ramp-rate" with some more overlap to reach his goal.
Which everyone else has already said. :roll:
Sorry for the cross-up, Thanks for bringing that to my attention.
Mopar to ya!
BBBanjo
Author:  Sam Powell [ Sun Jul 22, 2007 4:50 pm ]
Post subject: 
The cam is cheaper than water injection, but the install is not. Just a thought.
You can get a basic water injection kit for about $200. The more elaborate ones are around $300 and up. But you would not need anything elaborate. In fact, since you are not running boost, all you have to do is inject it directly into the TC through a vauum hose.
Sam
Author:  1974duster kev [ Sun Jul 22, 2007 5:36 pm ]
Post subject: 
Well i don't really have any input on the camshaft thing b/c i'm still undecided on mine also but....I'd say if you did wanna get maybe a bit more power depending on if you wanna spend the cash upgrade to some 3into1 headers for true dual exhaust (unless you still don't want headers Yes i read that 20page post about your build till 5am the other night).



Kevin
Author:  argentina-slantsixer [ Sun Jul 22, 2007 6:02 pm ]
Post subject: 
sam are we talking about pressurized water injection here?
Author:  Bren67Cuda904 [ Sun Jul 22, 2007 6:42 pm ]
Post subject: 
My problem would require a 2 stage injection system and would have to be sprayed in under pressure to atomize it properly. I get pinging at 1/2 throttle. One stage with enough water to control the ping at full throttle would be way to much at 1/2 throttle.

Lets stay on the cam topic.
I haven really heard many cam ideas here. I heard one, but what I really looking for is some numbers to tell a custom grinder.
Author:  LUCKY13 [ Sun Jul 22, 2007 7:36 pm ]
Post subject: 
I highly suggest you sign up on this forum & talk with the one that runs it. His cam will cost you more than you want I am sure. But the performance & the goal you are trying to achive will be meat with way more than you expect. He will want a hugh amount of info from you about your car. But in the end you will be glad you went with his cam.


http://www.yellowbullet.com/forum/forumdisplay.php?f=39

Here is a link to his web site for his company if you wish to go stright to him.

http://www.camshaftinnovations.com/


It would not surprize me to see hugh HP numbers gained, plus being able to step back to pump gas with his cam.


I think having someone like Jay to make you a cam is going to fix and anwser so much for you on your build. It is the one think that will bring it all together for you & make your efforts worth what you have put into this engine.

Although I do sugggest that you go with what ever torque convertor that he suggest you to run. You can still run a higher stall without it causing problems for your street driving if it is built by the right person, with the right size core to start with ( 9 1/2, 10" or what ever size is needed). Torque convertors have cam a long way. WIth the right person that know what is going on you will surpase the effectivness more over any of the off the shelf TC that you could buy. IN other words, you could have a 3200 stall that feels & works better for street driving than what you have now.


Good Luck, and by all means atleast talk to Jay about your cam. Your engine will totaly change with one of his camshafts in it. But dont expect him to give you any specs or numbers for a camshaft untill you have agreed or payed for it, he just want do it. You will understand why after you are running it.


Jess
Author:  Dart270 [ Mon Jul 23, 2007 6:40 am ]
Post subject: 
I really like the specs of the Scneider cam that BBB posted. You should be in pump gas territory with that one, and gain some power up high. Use 106-108 lobe centers (LSA). My calcs and experience have put me around 106, but you lose a little low end with lower LSA.

Just to be clear, you should have the INTAKE duration LONGER than the exhaust, and the intake lift higher. His numbers are a little crossed up there, the way I read them.

I agree you may want a higher stall conv after the swap, but I would wait and see...

Lou
Page 1 of 9 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/