Camshaft ... Lunati Voodoo # 62503

Camshaft ... Lunati Voodoo # 62503

Joined: July 1st, 2011, 12:17 pm

November 1st, 2011, 11:47 pm #1

Apologies to those who have posted many times on cams ... i have been through a lot of posts and gleaned what I can! Here goes:

Got a 351c I rebuilt with some help from a local company and father.

Spec:
40 tho over bore
KB pistons
ARP bolts throughout
Stock crank, not stroked
MSD 6AL ignition
Mallory mag breakerless dissy
AFD heads with 64cc
Roller rockers 1.73 ratio
Deck not zero decked but should be c 10 compression
Currently comp cams 268 XE cam (268 reported duration on inlet and exhaust, 218 at 0.05 on both inlet and exhaust, 110 LSA)
High vol water pump
About to fit a edel performer rpm airgap manifold, sittingin box waiting for me
And about to add a better baffled sump to it
Holley 670cfm street avenger which with displacement (and even with inefficiencies) should give plenty of vol into the engine up to 6k redline
thats about it ...

with 3.03 pl rear end, and 5 speed manual box. 17 inch rim with 255/45/17 on back and 235/45/17 on front

Power has been pretty good, never measured it though on dyno. And is fairly friendly in traffic as power comes in quite low in range (spec is 1500-5500), but its actually quite quiet at low revs ("relatively" quiet ... which is nice, but just wrong!!) and then it kicks in with a great noise c. 3k (maybe when secondaries open) and then starts to flatten around 5k IMO

Am thinking of switiching cam, and adding a different cog to allow timing of the cam as well to dial it in properly

My aim is NOT all out horse power alone, I don't mind a rougher idle and a little more pain in traffic, but want a good clean pull through the range but maybe a little more radical than what I have right now.

Was thinking the 270 magnum (1800-5800 spec, think lift is c 225 at 0.05) but part of me thinks that the heads I have with the springs and rollers could really manage a cam which opens and closes much more quickly i.e. a more modern design cam with more and faster lift

Looks based on my research like a roller cam really give you much more open time without increasing duration but not really up for the cost associated with that... so prob sticking to hydraulic flat tappet. Unless someone convinces me otherwise!

The 274XE has 274 (230 at 0.05) on inlet and 286 (236 at 0.05) at exhaust but think that might be too much for me?

One idea is this

http://www.lunatipower.com/Product.aspx?id=1623&gid=287
intake 268 or 227 at 0.05
exhaust 276 or 233 at 0.05
lift 0.552/0.564
range 2000-6000
LSA 110

So it opens nice and fast but total duration not too long, and LSA in sensible range in terms of having reasonable idle. This looks like a nice cam to my VERY inexperienced eyes!

They say 9.5 comp ratio which I think i am above so should be fine ... but suggest 3.55-3.73 rear gear ... am on 3.07 rear gear. So you think that would be an issue given the car is pretty light plus on a 5 speed manual gearbox rather than auto?

I do want a better sounding idle ... mine is nicely behaved but almost too well behaved at lower revs and then runs out earlier as well... plus with the performer rpm airgap manifold and the AFD heads I just feel like I should be getting a cam that fits in with those components better.

Views please!! Any comments welcome!

Al
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Joined: July 1st, 2011, 12:17 pm

November 1st, 2011, 11:56 pm #2

ps. brakes are also vacuum assisted ... nothin else running of the vaccuum
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Joined: October 1st, 2004, 8:05 pm

November 2nd, 2011, 12:45 am #3

Apologies to those who have posted many times on cams ... i have been through a lot of posts and gleaned what I can! Here goes:

Got a 351c I rebuilt with some help from a local company and father.

Spec:
40 tho over bore
KB pistons
ARP bolts throughout
Stock crank, not stroked
MSD 6AL ignition
Mallory mag breakerless dissy
AFD heads with 64cc
Roller rockers 1.73 ratio
Deck not zero decked but should be c 10 compression
Currently comp cams 268 XE cam (268 reported duration on inlet and exhaust, 218 at 0.05 on both inlet and exhaust, 110 LSA)
High vol water pump
About to fit a edel performer rpm airgap manifold, sittingin box waiting for me
And about to add a better baffled sump to it
Holley 670cfm street avenger which with displacement (and even with inefficiencies) should give plenty of vol into the engine up to 6k redline
thats about it ...

with 3.03 pl rear end, and 5 speed manual box. 17 inch rim with 255/45/17 on back and 235/45/17 on front

Power has been pretty good, never measured it though on dyno. And is fairly friendly in traffic as power comes in quite low in range (spec is 1500-5500), but its actually quite quiet at low revs ("relatively" quiet ... which is nice, but just wrong!!) and then it kicks in with a great noise c. 3k (maybe when secondaries open) and then starts to flatten around 5k IMO

Am thinking of switiching cam, and adding a different cog to allow timing of the cam as well to dial it in properly

My aim is NOT all out horse power alone, I don't mind a rougher idle and a little more pain in traffic, but want a good clean pull through the range but maybe a little more radical than what I have right now.

Was thinking the 270 magnum (1800-5800 spec, think lift is c 225 at 0.05) but part of me thinks that the heads I have with the springs and rollers could really manage a cam which opens and closes much more quickly i.e. a more modern design cam with more and faster lift

Looks based on my research like a roller cam really give you much more open time without increasing duration but not really up for the cost associated with that... so prob sticking to hydraulic flat tappet. Unless someone convinces me otherwise!

The 274XE has 274 (230 at 0.05) on inlet and 286 (236 at 0.05) at exhaust but think that might be too much for me?

One idea is this

http://www.lunatipower.com/Product.aspx?id=1623&gid=287
intake 268 or 227 at 0.05
exhaust 276 or 233 at 0.05
lift 0.552/0.564
range 2000-6000
LSA 110

So it opens nice and fast but total duration not too long, and LSA in sensible range in terms of having reasonable idle. This looks like a nice cam to my VERY inexperienced eyes!

They say 9.5 comp ratio which I think i am above so should be fine ... but suggest 3.55-3.73 rear gear ... am on 3.07 rear gear. So you think that would be an issue given the car is pretty light plus on a 5 speed manual gearbox rather than auto?

I do want a better sounding idle ... mine is nicely behaved but almost too well behaved at lower revs and then runs out earlier as well... plus with the performer rpm airgap manifold and the AFD heads I just feel like I should be getting a cam that fits in with those components better.

Views please!! Any comments welcome!

Al
It seems to me your goal is to have a motor that revs to 6000 rpm, is that right?

Lunati's VooDoo cam lobes and Comp's Xtreme Energy lobes are good lobes, but the cams they've designed with those lobes have wonky valve events.

When cam manufacturers grind cams on 110° lobe centers (lobe separation angle) it gives the motor a steep tire frying torque curve at the expense of a narrow powerband, power will fall off quickly beyond the horsepower peak. Then the cam manufacturers time the cam 4° to 6° advanced, i.e. the intake centerline will be set at 104° to 106° ATDC, this gives the motor more low rpm "punch" but closes the intake valve too early. An engine with a cam like that installed in it has no chance to rev very high, its going to flatten out early. To get a cam timed like this to rev to 6000 rpm takes an intake lobe with an advertised duration in the range of 288° to 292°, perhaps even more.

I'd recommend the Crane 284H12 or the Crower 284 HDP. These cams offer a good balance between valve event timing, overlap, duration at 0.050", and valve lift.

-G
____________________________________________________________

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If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
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Joined: July 1st, 2011, 12:17 pm

November 2nd, 2011, 10:52 am #4

Thanks for the input George

My aim is not so much to rev to 6000 ... am conscious that a lot of my driving is really lower down in the rpm range day to day, but 6k is about the limit I would ever go to. I don't mind if the peak hp is around 5500 or even below as long as it doesn't drop off too quickly.

Goal is to make more peak hp (and torque??) than current 268 XE cam, ultimately achieve better acceleration, but hopefully keeping the power band lower down in the range where i am more likely to use it, and achieving a car which is still vaguely useable in traffic (when you leave London for a good drive on UK smaller roads, the main roads are inevitably blocked ...)

Also, goal is to have a better sounding idle and low rev performance ... right now it sings when I open up, but is actually quite quiet in town!

The crane cam is rated power band 2600-6400 - I just worry that I might spend less time where the really HP is on this cam?

Seems like dialing cam in properly is very critical - I had no idea the first time I put the engine together, had never even heard of it!

Cheers

Al
Last edited by Alastair_Mayne on November 2nd, 2011, 11:03 am, edited 1 time in total.
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Joined: May 20th, 2005, 4:48 pm

November 2nd, 2011, 11:25 am #5

Most guys aim for a specific rpm peak or sound while not worrying about where they spend most of their time driving.

Adding more peak power while keeping low-end power is sometimes a daunting task. Ever thought about having the heads and intake worked on?

Increasing duration will most likely shift the entire curve to the right, which will give you a higher peak power but will take away the bottom/mid range power.

Changing the lobe designs to a more aggressive lobe could increase power throughout the range, but then valvetrain reliability could be compromised.




Brent Lykins
B2 Motorsports, LLC






Last edited by blykins on November 2nd, 2011, 11:28 am, edited 1 time in total.
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Joined: July 1st, 2011, 12:17 pm

November 2nd, 2011, 12:14 pm #6

Brent - thanks for the message. That is why I was thinking of the Lunati ... as overall duration is not very long (268 intake and 276 exhaust) so I assume low down performance will be good, but the lift at 0.05 is much higher and more area under the curve, plus much more lift, so I assume I get HP gain?

Does that make sense logically?

Have emailed AFD as when I got the heads I got the "complete street" package and i want to check what springs were on there and therefore if they would work with the cam.

Need to find who in the UK would do porting work on the heads and intake. And at some stage probably examine by exhaust set up to see how optimal / sub optimal it is!

Al
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Joined: May 20th, 2005, 4:48 pm

November 2nd, 2011, 12:34 pm #7

..to get an idea of where the engine's horsepower will peak. Advertised duration vs .050" duration will give you a good idea of how aggressive the lobe is.

If you added head flow, you could potentially gain horsepower along most of the powerband and it would also move the peak hp rpm up as well.



Brent Lykins
B2 Motorsports, LLC






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Joined: July 1st, 2011, 12:17 pm

November 2nd, 2011, 3:07 pm #8

The Lunati is 227 inlet at 0.05 and 233 exhaust at 0.05, but overall duration quite short really so guess it is a much faster opening cam with more pressure on the drivetrain ... hopefully Dave at AFD will come back to me soon and can work out whether the prings will work or will need changing ...

intake 268 or 227 at 0.05
exhaust 276 or 233 at 0.05
lift 0.552/0.564
range 2000-6000
LSA 110

GOing to look into head work!
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Joined: May 20th, 2005, 4:48 pm

November 2nd, 2011, 3:50 pm #9

...with the increased duration. However, if you plan to change the rearend gears as well, I think it's a good move.

Were you thinking about doing a roller cam too?

Brent Lykins
B2 Motorsports, LLC






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Joined: July 1st, 2011, 12:17 pm

November 2nd, 2011, 4:04 pm #10

.. COuld fit the 3.54 instead of the 3.07 but then got the messing around with speedo as it mechanical off the gearbox ... only downside is that I will be shifting gears almost instantly after starting, plus will hurt a bit on the motorway cruising as will push up my rpm at 70mph considerably. Might install cam and see how she performs, and then decide whether to increase the diff ratio ...

Thinking hyd flat tappet still, as don't want to go the expense of a roller cam / lifters / rest of parts requried to install a roller in an engine which didn;t have one previously.

Once I know re the springs I think I will go for it!
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