hosspowerinc

I know cam questions pop up all the time but I need some advise. I am building a 406 w/ vortecs and was basing it off this build
http://www.chevyhiperformance.com/te..._block_torque/
The article motor peaks at 5000rpm and Im thinking I want to move it up for around 5500rpm and shift at 6000. Im running a cast crank and hyper pistons so I want to keep it under 6000rpm regardless. Also the Lunati cam uses a 109* lobe seperation with only 230*@.050 lift. I would think this is only for a choppy idle and will hurt my overall fuel economy. What would you guys suggest I put in there?

blctalon

I built my engine based off the Impersonator II. That lunati cam is the same one I"m running and it is a 2000-6000 rpm cam. It has a mild idle, but it depends on what you're used to or comparing it to. Once the engine is warm it has no trouble idling at a stop, but again, it's not perfectly smooth.

I went the "competition AFR" route. I ordered my heads before the new eliminators came out. Either way, you want a good flowing head if you're only using a 180cc intake runner. I have a video of the "impersonator II" combo alive and kickin on youtube around here somewhere. It's the day after I broke in my cam and I've made some changes to it since, but still the same engine.

BTW video was for fun and on open headers. http://www.youtube.com/watch?v=nfl2GxfLhxs

MotorHead

THat writeup is quite interesting but why waste your time with building that when you can get the same torque curve as that motor has plus over 100 more HP if you were to use heads more suited for a 406ci. Sure it makes 525 tq but it should also make 575HP too not 428HP, that is a properly built motor IMHO

Can't understand this quest for torque. If you build you motor to make power the torque is going to be there. Anyway Vortec flow is not the best that is why they put a small cam in it. If you want to raise the peak HP RPM get the appropiate heads, those heads are good on a mild 350 not a big inch small block or should I say if you already have the heads you know what kind of motor you are going to build already, you might be able to step up the cam but I doubt it as you are limited to lift those heads will accept, less than .500" lift on a big inch small performance motor...jeesh

hosspowerinc

They did a vortec setup on a 350 that made 450hp and 450ftlbs of torque so I think the HP could be there with the right cam. Not 575 but at least 475 or so. The reason I would like to do this is purely power per $. The heads cost me $200 and intake $130. Its hard to make similar power for that kind of cash outlay. Also the heads can be cut for .575 for about $50 so you can get some decent lift out of them. Any comments on a different cam?

hosspowerinc

Should I just set up to the next size? Its a 246 @ .050 w/ .515 lift but it has 108* lobe seperation. It just seems to me that this would cause a lot of reversion.

dk-corvette

Hi Hoss,
For a budget build I would consider one of Summits own brand cam and lifter kits like this:
http://store.summitracing.com/partde...7&autoview=sku
It's very hard to beat this prices. I got one of there 1104 kits in my old 355 with a great result.
For a little more money you should look for a solid flat tappet instead. Bring the heads to Lloyd and have him fix a decent lift on them and give you some advice for pocket porting. This you can do yourself. He can also give you a good offer on a cam. I'm having a Comp XS282S for a 383 from him at the moment.
Best regards, DK.

The Money Pit

If you're set on the Vortec heads,I'd stick with the 230 degree cam,like the buildup used. I can vouch for the "matched parts" makes the best combination theory,since I've built dozens of different combo's. The Vortecs,though a great stock head,will not flow near what a big inch smallblock will need to turn the rpms,and make the HP. You will end up with a motor that has no lowend,and runs out of steam at 5000 rpms if you chose to over cam.May as well tweak the combo to run strong where it can run.

I'm on cam number three with my AFR 195's and though they are "small heads" have managed to pull decent power to 7000 rpms,but am running a solid cam and Vic Jr. intake.GKull,Motorhead,and others can jump in to say if you what to make power,you'll need more cylinder head.

73, Dark Blue 454

I agree with Motorhead above. Vortecs in a 406 would be perfect,..for a tow truck,..but not for a Vette that will see the dark side of 5000 RPM. I have AFR-195's in a 406 similar to your plan in a Camaro and I wish I had gone bigger.

This noise about torque is killing me. In a 406, you have torque by default. Go with heads with a least 200cc, and I even advocate 210's (but not sure what tranny and gears you're running). Why would you want to leave HP on the table (50+)?

Torque vs HP? Let's say we have two similarly built cars and engines, and we'll race. You shift a bit past peak torque and I'll shift a bit past peak HP and we'll see who wins.

Lastly,..here's some good info:

http://forums.hybridz.org/showthread.php?t=100261

cardo0

What compression ratio?
What type trans?
What rear gear set?

Just because u want to shift at 6,500 with a 230* duration cam doesn't mean u can run hwy gearing and 8.5 compression through an auto.

What loge separation angle?
What's full duration?

I can give u an answer now but it would be very conservative to be safe in any 406" sb with vortec heads.

cardo0

hosspowerinc

Im running a T5 with a 3.70 rear gear. Compression depends on the cam choice. For the 230* it would be 10.1:1 with a dcr of about 7.5:1. Im not sure what you are asking about the lsa and duration. Do you want the specs on the bigger cam Im thinking about or the one they used in the mag combo?

hosspowerinc

I really dont want to make more power, just move it around and have some trade offs. If I can lose a little torque down low and gain a few hp up top, Id be happy. That much torque that low will blow my tires away anyway. Maybe I should just retard the cam some. Maybe 4*? As I said before, with a cast crank I really need to keep it under 6000rpm and under 500hp to be reliable. If I go swapping for bigger heads I will then be needing another 2k for a forged bottom end. I just dont have that kind of cash.

The Money Pit

I tried a Strip Dominator and Holley 850 on an otherwise stock 350 Olds 350 once and it ran OK.....but for sure was not matched up well for peak power.Had a softer bottom end,pulled like Godzilla from 3000-5000 and piddled out after that.

There is no one right way to get what you are looking to achieve here. Sure a larger cam will work....to a point. When the head flow can't keep up with the engine damand,the power curver will go flat.The problem I see with that approach is the lowend will suffer too,so you'll loose out on both the top and bottom end power. Maybe a single plane intake would shift the curve better to what you're trying to do.Much easier to swap back to a dual plane if it doesn't suit than a cam.

hosspowerinc

I know where your getting at. You can only get max power when all the parts are matched. Im just thinking that the vortecs may have a little more to give. Check out this build
http://www.popularhotrodding.com/tec...c_small_block/
Thats 450hp out of a 350. I realize that I am limited by flow but I think I can get some more hp out of them. I saw a build that made it to 500hp with stock vortecs but I cant seem to find it again. I guess i need someone with desktop dyno to run a bigger cam and see what happens.

cardo0

3.70 gears with a T5 should be fairly steep in first gear so getting it rolling with a lot of duration and overlap is not an issue there. But the 10.1 c.r. with iron heads sounds like your testing the limit on detonation hoping the d.c.r. will make it safe - good luck.
The Vortec heads have very small vlvs. This will reduce cyl filling/breathing - even worse with 406 inches. To maximize cyl breathing/torque u need to tighten the LSA - which inturn will increase overlap.
To me it just sounds like u are going in the wrong direction. U want to tame a torque monster 406" into a high rpm winding comprimise. I don't think u will get it. Those small vlv heads with large displacement under them will quit breating early regardless and only make the same pwr as a little 350" mtr at hi-rpm.
I'm just guessing here your full duration numbers are well over 290*. FWIW if u want to max pwr with those Vortec heads and reduce d.c.r. then use a tight LSA - like 103* or 104*. Yes, only 103* or 104*. This will allow short duration cam - less than 280* full duration - and require less spring force and longer cam life. No, this won't get u to 6,500rpm but with those heads u won't get there anyways.
But between 2,000rpm and 5,500rpm wear a neck brace - big block power and torque.

Good luck.
cardo0

hosspowerinc

Thanks Cardo0 for the reply. The cam they used in the mag build is a adv. 292* duration with a 109 lsa. Your suggesting running a lower duration cam with more lsa to help bleed off the compression or make more power? The compression isnt set in stone on this motor as I havent bought the pistons yet so that can be adjusted.

I understand that hp is only how much torque you have at a higher rpm and your saying that the heads are absolutely maxed out by 5500 rpm and asking anymore would be impossible?

EDIT: upon rereading your reply I am following a little better. What duration cam would you recommend me try? I am having it dynoed before it goes in the car so if the numbers are off then I can swap out cams and try again. Also who makes a cam with that low of lsa? The lowest I can fine at summit is 106.

Little Mouse

Anyone think about how poor the percentage of valve area is on
400+ cube small block when you stick 202/160 size valves on it.
For instance the percentage of valve area on a 302/327/350
with 202/160 valves is extremely good in comparison to big blocks
that only have a little bigger valves of 219/188 to feed 396/427/454
cubes, on a 454 the intake valve only .17 bigger is trying to feed
another 104 cubes over a 350. Percentage of valve area is very
poor on big blocks in comparison to small blocks, thats one of the
reasons a big block has such big runners in comparison to small
blocks they don't have near as good a percentage of valve area to
work with for the amount of cubes they have. You stick a punny
170 to 180 runner on a 400+ size small block then add in a way to
small 202/160 valve area opening, you have nothing for a head.
You had better put some form a decent size runner behind those
202/205/208 valve size small block aftermarket heads for a 400
size small block. If you really want to strangle your engine to death
combine a to little valve opening area with to small a runner, after
you have done that adding a little more dur.and lift on the cam
will do next to nothing to help you.

cardo0

U need to contact the mfrs to ask for special grinds. But Lunati had some oval track hyd cams and Power Master cams with 106* LSA in the 280+* duration range - the next best thing to 103*/104* LSA. And Crane had some Saturday Night Special cams with 106* LSA and 280+* duration. Sorry but the online catalogs are not very user friendly and i burned up an hour at least look'n for ya buddy. Tried Comp, Isky, Crane, Lunati but man then i start looking for cams i want and this search could take forever.
But again u need to contact the cam mfr for special LSA grinds at maybe not much more money at all (maybe <$100 additional).

Glad to see u pick up on this cam timing for your application. And i really like how u are trying to get the most hp per $$$ rather than throw $$$ at parts u don't know u really need - your learning.

BTW Mr. Mouse, the Vortec has only 1.94/1.55 size vlvs so the percentage of vlv area is even smaller. And even the 327"/350" sb Chevys were vlv limited - the biggest restriction in the intk runner is the vlv.


Hope this helps.
cardoo

Little Mouse

Yes I know the vortec head has smaller valves then 202/160 valves
and 327/350 size engines have very good area compaired to 396
on up big blocks, problem for stock head poor flow a 160 runner
behind the valve. you put a modern 180 runner AFR head on your
350 with 200/202 size intake valve your engine will come alive like
never before with a small cam or a bigger cam, you notice they
dont make a 160 runner head waste of there time. 160 runner like
a factory head good for 265/283 and low rpm 302/327 size engines.
problem with factory heads chevy kept building bigger engines with
no changes to the runner, same runner 302 then 327 then 350 then
400. Even A 350 is starving for air thats why the 180 runner wakes the
engine up big time. 400 with 170 to 180 runner its starving to death
for air now with both to small a runner and to small a valve opening
area.

blctalon

My little 406 with 180cc afr heads must be starving for air then. Sure does run good at only half throttle. Need to fix my throttle cable so I can starve it all the up to 6 grand or so when the secondaries open.

MotorHead

Put on a set of 210cc heads matched with the proper cam and you see how much it is starving. 180cc heads were disigned for a stock to mild 350ci motor.