Help me cam this 512

[firefighter3931]

Was looking @ a couple of engine builds a guy did , one was a 350 Chebby , the other a 510 Ford , the Chebby made 750 HP @ 7500 RPM , the Ford made 1100 HP @ 7500 RPM , both used the same duration , & i always thought the larger the displacement the longerr the duration.

Adam, the cylinder head flow will determine how much power the engine makes. The cam's duration just defines where that power will come in at and finish off. The bigger displacement Ford Motor would have much better flowing heads along with more cubes to make the difference in power between those 2 examples. That's probably an oversimplication but generally speaking, the theory would hold true. Flow=Power....getting it to work properly in the right combination for the car is another matter. 



Ron

[Challenger340]

I've run that Cam before on the stock 108 lsa, @ 11.5:1 with Aluminum head, and I don't recall any detonation on the Dyno with pump fuel, when Scoping the plugs.

Probably safer reground though, see what Comp. says, your call.

[firefighter3931]

I've run that Cam before on the stock 108 lsa, @ 11.5:1 with Aluminum head, and I don't recall any detonation on the Dyno with pump fuel, when Scoping the plugs.

Probably safer reground though, see what Comp. says, your call.

Bob, when you ran that cam in an 11.5:1 motor....what was the displacement ? Elevation ?

2 critical factors to consider, inmo. 



Ron

[Challenger340]

500 lowdeck, 6.76 Rod/4.15 crank, (with the 2.500 mopar journal AND internal 1/2" oiling), a little bit tricky.
We'd bolt a jig as a guide for the endmill bit, to the panrail, and drill the pilot hole offset for the 1/2" oiling.
Nowadays, we just go 2.200, wayy simpler !

We're pretty high, about 4200 most days, with the westerly's.

The "ragged edge", but I like the port reversion down low on the 108. I dunno if he's got enough head/balance for the 110 or 112 on the big motor ?
You know the street alot better than me Ron.
You think that Cam will work OK @ 112 ?

[firefighter3931]

Bob, the only thing that concerns me is the elevation and high static compression....the 108 will trap too much air down low and send it into detonation. Pump gas builds are tricky and require some compromises. 

As for the heads...sure they are a bit on the small side for the displacement but it will make killer torque across a pretty wide powerband....with the wide lobed stick. The wider lobes seem to extend the top end power pretty good with these small head stroker builds. Torque won't be a problem with the long arm crank and at 2600 lbs this thing will be a rocket ! The reworked heads with big valves and the tunnel ram should give it a very nice top end charge....i like this combo ! 

I could be way out to lunch......but that's how i would build it 



Ron

[Dartbloke]

Some great input here guys! First time I've seen those EDM lifters, will use those for sure. I don't think air temperature or elevation will be a problem here in the UK, the 440 I have in there now I can keep at 185, so i don't expect that to be a problem either. Came across this mod today on another board, guy had drilled small oil return holes in the valley, aimed at the cam lobes. I will have a closer look at my block and decide if I like that idea or not.

[firefighter3931]

I don't think air temperature or elevation will be a problem here in the UK, the 440 I have in there now I can keep at 185, so i don't expect that to be a problem either.

DB, the elevation will affect your static compression ratio. Someone building a motor to run at 4000ft above sea level needs to increase the comp to account for their elevation. Put another way; a motor built for 10:1 at 4000 ft would be equivelant to approx 11.5:1 at sea level. Elevation plays a huge role in how an engine will run and behave. 


Ron

[Dartbloke]

Yes I appreciate that Ron, what I was meaning was we can't be more than a few hundred feet above sea level here.

[firefighter3931]

Yes I appreciate that Ron, what I was meaning was we can't be more than a few hundred feet above sea level here.

[Steve P.]

I would love to see the dyno sheets from this build..


With a 14.5 tire on it you should do well, but this is going to be an animal. While reading along I am thinking throttle stop more and more...  This car is going to need a name.... 



Hope you have a Dana... 

Oh, and welcome... I think you'll like it here.. 

[Dartbloke]

It already has a name!  Dana is on the to do list, need to decide what ratio to use, I'm thinking less than the 4.10 I use presently....

[Animal]

Won't this build make less power/torque running @ a high static compression ,considering the 'band aid' to get it to run on pump gas?

If the motor is built for 10.5:1 SC to run on pump gas , the cam can be ground on a tight LSA , therefore filling the cylinder earlier & closing it earlier , therefore raising the DC , maximising torque.

With this build , the LSA has had to be widened along with a longer duration , bleeding off cylinder pressure , in the hope detonation won't be a problem , this could lead to less power/torque , than if the motor was built with a SC of 10.5 :1.

High compression motors fair better with tight LSAs (early EVO) , to which is the opposite on this build.

Going by what RON & Bob are saying , maybe drop the Sc ratio John.

[Dartbloke]

Adam, I've been reading some stuff written by David Vizard about pump gas engines. In his tests he found that the higher the static compression coupled with enough duration saw the HP rise, sometimes by quite large amounts. We'll see how it works out, if it all goes wonky bent I'll lower the compression a point and re cam it.

[firefighter3931]

Won't this build make less power/torque running @ a high static compression ,considering the 'band aid' to get it to run on pump gas?

If the motor is built for 10.5:1 SC to run on pump gas , the cam can be ground on a tight LSA , therefore filling the cylinder earlier & closing it earlier , therefore raising the DC , maximising torque.

With this build , the LSA has had to be widened along with a longer duration , bleeding off cylinder pressure , in the hope detonation won't be a problem , this could lead to less power/torque , than if the motor was built with a SC of 10.5 :1.

High compression motors fair better with tight LSAs (early EVC) , to which is the opposite on this build.

Going by what RON & Bob are saying , maybe drop the Sc ratio John.

Adam, what you are saying is essentially correct....the wider lobe seperation will make less peak torque but it will have a much flatter torque curve. With a light car that will see a lot of street driving this isn't really that much of a consideration....the car will ET very well at the track none the less. 

Now if it was a strip only motor and i was building it....a 14:1 static compression ratio with a tight 106-108 lobe center & lots of duration would be my preference.  But that type of motor works in a narrow powerband and isn't very streetable. 


Ron

[Animal]

Good to see you over here John.

As i've said before , a minefield of info on this site , just wish the guys on our site in England would share the info a bit more.

[Jon Smith]

Some of us just dont know what we're talking about

[Animal]

Some of us just dont know what we're talking about

Hi Jon , you said it.

[Jon Smith]

I was referring to you

[Animal]

Sorry Jon , i was'nt refering to you.

[Dartbloke]

Sitting here waiting for parts is murder, I really want to get on with this thing......

[Dartbloke]

Finally putting this motor together at the moment, there was talk of the cam having advance ground in, but there is no mention of it on the cam card. should I install it straight up at 112?

[firefighter3931]

Interesting cam card....it appears that there is no recommended installed intake centerline....just the valve timing events based on a 112* installation point. 

Maybe they're assuming that it's going to be degreed in anyway 

If it were mine, i'd be degreeing it in at 108 and see how it runs. 



Ron

[Dartbloke]

Thanks Ron, I'll try that then.