Hey guys,

My brain is fried on camshaft jargon after spending the whole weekend surfing for cam specs, here, there and everywhere. It seems very few are prepared to share thier knowledge on thier spec, and even fewer are even happy with thier current cam.

I have narrowed it down to two, one off the shelf, and one custom ground.

The combo......

383 cube SBC, 5.7" rods, 8.8:1 forged pistons, AFR210 race heads, 1.55:1 rockes, victor jnr manifold, CSU 750 carb, 98 octane fuel, 7200rpm limit. The car weighs 3400lbs and runs a braked t400 with 4200 stall. 3.7:1 gears and 26x9 slicks.

the cams......

Howards Cam. Duration at 050 inch Lift 246 int./246 exh. Advertised Duration 286 int./286 exh. Valve Lift 0.601in. Lobe Separation 112.

Custom Cam. Duration at 050 inch Lift 254 int./254 exh. Advertised Duration 292 int./292 exh. Valve Lift 0.601in. Lobe Separation 114.

What do you guys think???????

The Howards Cam is $300, the custom is $700. Just in case that influences your decision.

 

I'm doing the basicly the same build for a TT sbc street/strip car . this is what my grinder came up with .

Hyd Roller : 238/232 @ .050 , 115lS , .570/.570 valve lift (1.5) , Advertised Duration 296/288

 

Contact CDR Performance in I think they can do a custom roller for about $400.
http://www.cdrperformance.biz/customcam-shafts.html

 

CDR is back in business....interesting.

 

That hydro roller is a lot smaller that what i am looking at. What kind of numbers are you chasing? I am looking for around 750fwhp.

Plugged both cams into Engine Analyzer last night, ad got some intresting results. Both cams seemed to come on strong around 4500, which is right when the boost is coming on too. The custom cam seemed to come on stronger hp wise and peaked over a little earlier, whilst the howards cam was 20-30 hp down till 6000, then 10 to 20 up from there on. I'm still chasing accurate numbers for the turbo to put into the program though.

Any more thoughts?

 

Try this one . Not recommending it , just curious what the analyzer says . Well I would recommend it , but most look at it and say its way out of whack . LOL !

This is a hydraulic roller for a 383ci , 6" rod , 8.8:1 , AFR 195s . No dyno numbers . 140mph / 4400lbs 6500rpm

Got it from Custom Cams / CDR

#ad

 

I'm looking for 850-900 RWHP with good street manners on a EFI 383 with twin T67's . the only thing the cam grinder suggested was that I use a 1.6 rocker to increase the valve lift to .608" .

 

Sure is!

There is much more to camshafts than many others know. Call Robert at CDR Performance, he can help.

 

I got a custom hydraulic roller from Mike jones. Happy with it so far but I wish I went abit bigger for more rpm. This motor is a 401 sbc with victor E EFI single plane with twin 60 mms. AFR 195 heads. Low rpm usage, shift by 6000 or so so far. Havent had a good dyno readout with rpms to verify but so far seems to make power to 5500-5600 and i shift it near 6.

Its a 292/292 advertised 233/233 at .050. 112 lsa installed on a 110 icl. .564/.564 lift with 1.6 rocker. Dyno was 640whp on mustang with 12.5psi. Converter was loose and with pig rich tune, it did 690 at 17psi. I expect closer to 750whp on 15psi once tuned up. 3550lb car or so traps 141 in decent air with just a street tune on 14 psi.

For you with abit more RPM goal, add 5-10 deg more duration. Keep it a single pattern or close to it and 112 LSA or so. Seems to work well with most turbo builds I've seen. Dont need a big cam to make power tho, especially 750 flywheel. I'd run a 240/240 ish cam for mid 6000 rpm performance, keep it under 7200 for the shift.

Dont need a solid roller to do it either but its nice if you want to deal with those. You can get a custom grind for 300-400 bucks at 90% of cam places. Anyone charging 700 is out of their mind unless its some special material for the core and some odd firing order swaps/etc or different sized journals etc.

 

Intresting your using 112 LSA. Everything a have heard or tried in the desktop dyno pionts to wider lobes. I think i am nearly set on a grind now. Its a local company 'Crow Cams', $712 including tax. 245/251 @ 050, 288/292 adv 598/601 lift on 114 centres. The desktop says peak power at 6600 and peak torque at 4700.

Bear in mind on price, a $400 us cam, is a $580-$600 Aud cam, and its on the other side of the world, ground by someone i will never see face to face, hence why i think i will go local for the extra dollars.

 

That cam has some pretty steep lobes. Its a hydraulic roller right? Need light valvetrain and strong springs to control that under boost. Wider LSA and/or less duration split between intake/exhaust is to keep overlap down. Helps fight reversion since exhaust backpressure in the manifold is near 2 or more times the pressure of the intake side in a typical turbo build. Generally why most turbo cams dont have alot of exhaust split. Supercharger cams however do have more split since they need to get rid of exhaust out of the cylinder. Similar to some nitrous grinds.

I think if you can control the cam lobes it will work out well for you.

 

No, its a solid roller. 440lb springs.

 

The cam that your pretty much dead set on seems like alot of money to me even if its "custom". It looks more suited to blower to me not turbo. Take another look at the cam blown385 suggested. He is making some pretty stout numbers with that thing. He gave you the specs. Just see what 'Crow Cams' would want to do it to try and keep it local.
Its a proven cam...



And if crow cams are a good company they should know a good turbo cam.

 

Tried the hydro roller in engine analyser. Gave some intresting results. peak torque and hp was lower by near 1000 rpm. average torque was up by 3ft/lbs, average hp up by 7hp, once i cut the pull short to 6000. peak torque down 45ft/lbs, but is now under 4000rpm. both hp and torque are falling off rapidly after 6000, down to 430ft/lbs at 6000.

I dunno bout this. I say its a street car, but its probably lucky to do 1500miles a year, and has slicks fitted for most of the months. it certainly seems that i can make big power and torque numbers with a little cam, but if i wanted something smooth and progressive, i'd turbo my daily and make 700hp.

Having had little experience with driving these type of turbo cars, it seems whether the power is on at 3000 or 4000, the number between then and the limiter, seem to go up in smoke, in any gear at any speed. I think i would rather it more agressive and use more of the available rpm, than maxing it out at 5500.

Am I crazy?

 

I think not, more RPM with less boost (assuming your motor can take the RPM) should live longer... not to mention the drive train

 

With a solid roller, i'd probably add another 3-4 deg duration to that cam if you want to spin that motor up 6500 rpm or so peak power. I'd still shoot for a single pattern cam with the head flow. AFR's have decent exhaust/intake flow ratios so single patterns work well.

For your hp goal you dont need alot of boost or alot of RPM. Once you start pulling more rpm, you start to fall on the low side of the compressor map since pressure ratio goes down. You need less boost to make the same power so you just move down the map. Just need to pay attention to the compressor map. Just an example, 5500 rpm peak 383 for 750 flywheel hp. 1.86 pressure ratio at roughly 75-76 lbs/min flow. Requires 12 psi to hit that power.

Now a 6500 rpm peak 383. 1.58 PR at same 75-76 lbs/min. requires only 7.8 psi to hit that power. You can see on the map you drop 1.86 to 1.58. Harder to find a turbo to fit that low pressure ratio range, just looking at garrett single turbo maps right now. GTX4508 may be ok for the higher PR lower rpm motor but lower PR it drops off near choke and efficiency falls alot.

 

Thats cool. Sounds like solid calculated numbers. So more like 251/251 or 254/254? There are good fairly agressive roller profiles for both available, with .600 lift. 114 centres again?

I definately want to shift between 6500 and 7000.

 

Which is it? 6500 or 7000.... they need different cams.....and exh housings.
Blown385 shifts at 6500 with his cam and smaller heads.
To convert his cam to a SR, a tight lash cam would be about 8 degress bigger at .050 or around 240-242. The more common lash SR w/.022-.024 would need about 10-12 degrees added. Or around a 246 @.050. A 248/242 115 lsa would be a ball park 7k shift. Your looking at springs with 210/520 or so for the more streetable cam lobes. If they spec a 250 or more spring then it has race oriented lobes and isn't really needed for your goals.
You might email Lunati or Comp and ask what it would cost for a custom billet core cam in HR or SR. It sounds like your local co. may be doing that already and just adding some markup. The old Comp 288AR SR on a 114ish LSA would be real close to what you want. But with those heads you'd need more lift to fully utilize them. Which means newer lobes. I personally like the Lunati Voodoo line. Lots of lift but still a street roller profile and seem to be less sensitive to valve train setup than the new Comp stuff. -you'll need good push rods too- Manton, Trend, etc.....

For running it through an analyzer, I'd just use normally aspirated and 11-1 CR. That will give you the HP peak rpm, shift point, etc. Then just multiply that horse power number by the PR you want to get the boosted HP.

-Now that I look at Blown385s' cam card, that looks like a voodoo lobe. The 108 LSA surprised me though. That may be why his combo doesn't seem to want to go beyond 6500.- Among the many other things discussed on his build thread.

-The voodoo lobe designer for Lunati lives in MS btw-

 

Wasnt that guy named
Robert? Part of Chaos racing?

 

He is still named Robert .