Some 1.6 RRs would add some lift and 5-10 hp on stock heads.
They could be used on the next engine too!

JMHO

R

 

I disagreed with your choice, probably more strongly that I needed to or should have. I didn't expect anyone to be remotely this fragile about a cam post on an internet forum... Most people can handle a more spirited disagreement than this; don't go on YellowBullet...

I can admit the Voodoo 256 fell over much faster than I expected it to; I get 4,500 RPM, not 4,000 with DDyno 2003, but I definitely like the 262 and the 268 better now and CERTAINLY in the future with good 64cc heads.

The Lunati Voodoo 268 has less overlap, more vacuum, vastly more torque down low, way more average torque and 9 hp less @ the peak (500 RPM lower, probably better for the cast bottom end), but the 268 is better all around with new heads. It's a lot of bang-for-the-buck gain for $80; that's what the faster modern ramps get you, and that's been my point since the beginning.

The Jegs cam was better than I expected, but still down compared to the Voodoo 268 in every aspect except it wins by 1 HP at 500 RPM higher and only on the 882 heads; on good heads it loses there, too.

Zinc additive or oil is required in all flat tappets, so that's not really a consideration either way.

The difference is the difference, the question is whether it's worth $80 to the op or not.

Adam
P.S. I did NOT evaluate the lumpiness of the idle and never do. My cam recommendations will give you a "boring" idle, but great average torque, good hp and good mpg.

 

 

 

The funny thing about this discussion is that you can build these cars into a MUCH more modern handling, riding, steering, and powerful car using the basic C3 platform without radically altering the basic design if you want. I did/have done this transformation over 35 years and did it with my engine specifically with the rebuilt/upgrade of the OEM L-82 in 2014. My brakes, steering, and front and rear suspensions are all the basic OEM GM design BUT with upgraded components that vastly improve upon the OEM feel.

As for my OEM L-82 engine with 66,000 miles on it at the time of the upgraded/rebuild (220 NET HP Stock/233 RWHP with basic HP upgrades to the OEM components), I specifically set out to keep it looking and feeling like an L-82 BUT with tons more power (you can search my threads if you are not familiar with the details). Not a different motor (383, 427 SBC, 454 BB, 496 BB, 502 BB crate engine, No LSX engine, etc) but the basic L-82 350 bored, using the L-82 forged crankshaft, L-82 rods, L-82 aluminum intake, GM dual cold air intake system, a 4 BBl carb, no Fuel injection, but 10.2 compression, AFR aluminum heads, a howards Roller cam, roller tipped rockers, etc. The L-82 355 looks, sounds and feels mostly like an L-82 but goes like stink..125-150 MORE HP than the best the L-82 had to offer right before the rebuild.




My car is so far beyond the stock L-82 4 speed with a GM gymkhana suspension it is really hard to believe that it was possible. The car handles, steers, rides, and has more power than some modern sportscars. Can it out do my 10 C6Z06? Not a chance but it is certainly much closer today than in 2014.

Don't let Nostalgia fool you...it can be done leaving the basic character of the car intact...I have done it and others as well.

 

 

I have said this before and I will say this again, in my opinion, the 383 increase of 28 cubes (not 33 cubes for a 350) is way over blown versus a properly built 355 in terms of HP and torque. The difference in HP/TQ for typical 383 versus a 355 like mine with 10.2:1 compression mild duration .525 lift roller cam with AFR heads is VERY small. Now if you build a 383 with 10.5:1 compression with AFR 195's with a slightly higher duration cam with the same .525 or higher lift, of course, the 383 will make slightly more power/torque at a slightly lower RPM BUT it is NOT a hugh difference. You need to go to a 406/427 SBC for a BIG difference versus a 355/383.

I estimate my 355 L-82 to be right in this range of 440-450 Gross HP @ 5,800 RPM with similar torque in the 4,500 RPM range:

http://www.superchevy.com/how-to/148...-engine-build/

with this result: "Final power pulls at Duttweiler's dyno delivered some excellent power numbers with a peak of 425 hp at 5,800 and max torque of 440 lb-ft at 4,600 rpm. Those numbers are worth 12-second times in any decent street car."

Also this from Super chevy:

The first 100hp increase was easy, but each successive jump in power becomes more and more difficult. Though we could get away with using the as-cast RHS heads at this power level, we decided to try a whole new combination. Off came the 100hp upgrade parts and on went a new set of heads and induction system. The basic short-block remained the same, but the 355 received a new set of AFR 195 Eliminator heads. For this application there was no need to step up to the Competition package, but the Eliminator heads featured 65cc chambers, a 2.05/1.60 valve package, and flow numbers to support over 550 hp. The same dual-plane intake and a Holley 750 HP carburetor topped the AFR heads. A good portion of the extra power came from the cam upgrade, a Comp Cams XR276HR hydraulic roller cam. The XR276HR offered a 0.502/0.510-inch lift split, a 224/230-degree duration split, and 110-degree LSA. In addition to the cam, Comp Cams also supplied the necessary lifters, pushrods, and stainless roller rockers. After installation of the new components, the 355 produced 449 hp at 5,900 rpm and 446 lb-ft of torque at 4,600 rpm.

Note the below 383 typical Hp/TQ and RPM:

• HP & Torque: 430 HP / 450 FT LBS
  Compression Ratio: 10.0:1
  Aluminum Heads
  Hydraulic Roller Cam
  Cast Steel Crank
  Hypereutectic Pistons

Same 383 engine flat Tappet:
This 383 Chevy "Stroker" motor is a Speedway Exclusive! Machined and assembled at BluePrint Engines, each Small Block Chevy engine is dyno tested (includes individual dyno sheet) and comes with a 30 month/50,000 mile warranty. Each crate engine is built to crank out 420 hp @ 5200 rpm and 450 ft.-lbs. @ 4300 rpm.

Dyno Sheet (PDF) (Note: This sheet represents one example engine. Your individual engine may differ slightly.)

• 420 hp @ 5200 rpm
• 450 ft.-lbs. @ 4300 rpm
• 4-bolt main, 1-piece rear main seal seasoned block
• Passenger side dipstick
• Chrome valve covers and timing cover
• New plain steel oil pan
• New cast steel crankshaft
• Rotating assembly balanced to within 2 grams
• Harmonic balancer
• 153 tooth flexplate w/ single 3-bolt converter pattern 10-3/4" bolt circle
• Hypereutectic pistons
• 10:1 compression
• Hydraulic flat tappet cam
• Heavy duty double roller timing set
• Performance aluminum cylinder heads
• Hardened retainers and performance valve springs
• Aluminum dual plane intake
• New HEI distributor
• 2500 stall converter recommended

The numbers do not lie

The 383 makes about the same Gross HP at a slightly less RPM (5,200 versus 5,800) for a whopping 600 RPM difference and the 450 GROSS torque is about the same for both @ 4,600 RPM for the 355 versus 4,300 RPM for the 383...a whopping 300 rpm difference. A no there is tons of documentation that AFR's with roller cam in a 355 makes over 400 ftlbs of torque over a very wide RPM.

Again a 355 and 383 built exactly the same, the 383 with 28 cubes more will make slightly more HPTQ but the typical street 383 really does not noticeably have more power than a properly built 355 as described above. Yes it is more, but not by much. I think a typical 383 versus a typical 355 today difference in power is at best 20-25 Gross HP/torque at a slightly lower RPM, call it 400-500 RPM or less. When you are dealing with 400+ gross HP for both street engines that difference is very small and hardly noticeable with those power levels.

Forget the 383 cubes and get the right cam and heads to give you the power you are looking for from your 350 as Adam suggests.

 

Since you have the AFR heads which will flow the extra lift.
I would be interested to see what your engine would do w/ 1.6 RRs?
You would gain about .035 lift, that has to be a few more CFM!

​​​​​​​R

 

Good suggestion!

I will ask my engine builder who built the bottom end of the L-82 355 what he thinks with my engine. He is an expert on building hi performance GM engines and worked for 16 years as a GM field technician teaching the GM mechanics at dealerships. He will be able to tell me if the 1.6 rr would amount to any measurable increase with my engine since he has his own in shop MUSTANG dyno and can gauge what changes will do to hp.

 

This topic has been covered long ago.
The consus was 5-10 hp for stock heads w/good ex that can use the extra lift.

For performance motors many were already using max lift.
For a street engine that does not want more rpm.
And can use the extra lift, I think it will help a lot.

Your cam is .525 in.
The AFR heads should flow a bit more at .560!
Not sure how much, I don't have the flow charts? lol

Please keep us posted!

R

 

I currently have the Lunati 268 cam in my motor, so maybe I can give a little first hand experience.

First off, let me say I would NOT reccommend the OP puts the 268 cam in an L48 with stock heads. I am currently running Brodix IK200 heads with 64cc chambers and a .015 shim head gasket, so I have an extra 1.5 points of compression over stock and considerably more flow than the 882 heads. And with that that, the 268 cam seems to work well (after alot of fine tuning thanks to some help from Lars and Cliff Ruggles on my Qjet). I also have 3.55 rear gear and a 4-speed. That cam with less than 8:1 compression and heads that don't flow is a combination that will feel pretty lazy.

OP I think you need to decide what you want to do. The way I see it is, you find some decent heads now (since it sounds like you are on a budget, I would say find some cheap Vortecs. They will raise your compression ratio enough and give you a good chunk more flow to utilize a bigger cam) and install a cam that will match your combo, or you get a cam that will go with your current combo (maybe the 256 or 262 Lunati). Obviously the second option is cheaper, but will make WAY less power. A stock bottom end L48 with a cam and headers will most likely push out something like 200-220 whp if you have it tuned and timed right. A stock bottom end L48 with some good flowing heads with smaller chambers for more compression and a bigger cam with headers could put you potentially close to 300whp.

 

Thanks for putting in that detailed response and time in Desktop Dyno. Should really help the OP see the numbers, and was a good read!

 

I have AFR 180's so not so sure more cam lift will help below 5,500 RPM but I will ask him. The AFR 180's are suppose to have better low and mid range torque/throttle response on a 355 versus the AFR 195's. I have to tell you my low RPM throttle response with the AFR 180's is surprisingly crisp

 

I think the extra lift is probably not worth the cost of 1.6 RR, unless you need to replace rockers anyway. I couldn't find flow numbers above .500 lift for the 180 heads, but here are the numbers for the 195 heads:195cc Street Head Flow Chart.200.300.400.500.550Int146201247275280Exh119166197213218
So it looks like at your max lift, you aren't gaining a ton more after the .500 mark. So I would agree with the earlier assessment: roughly 5-10 hp. So possibly worth it depending if you have the money just burning a hole in your pocket! Also depends on how well matched your cam is to your combo, since 1.6RR will also SLIGHTLY increase the duration of the cam as well.

 

I believe that yanking the valve open quicker and higher is better up to the point of mech problems?
Is it called valve saturation point?
Going a little above means more cfm all throughout the valve travel.
Does that make sense?

Anything more than .570 lift I would agree w/you!
I am curious about this too! lol

R

 

They say 255 cfm @ .500, 260 @.600

Is 5 cfm = 10 hp?
AFR Street 180cc

Aluminum

2.02/1.60
AFR Street 190cc

Aluminum

2.02/1.60
AFR Race 210cc

Aluminum

2.08/1.60
Edelbrock RPM
.

.
Edelbrock

23 deg


Chamber Size74cc & 68cc74cc & 68cc76cc64cc & 70cc71ccIntake Runner180cc190cc & 195cc210cc170cc212ccExhaust Runner64cc64cc80cc60cc60ccFlow Int/Exh @

See footnotes: *10 *10 *10*4 *40.100?/??/?72/6178/690.200129/108129/108135/112134/105140/1160.300195/156195/156197/145188/140200/1580.400240/178240/178245/185224/160242/1950.500255/190260/190273/205233/172270/2130.600260/194262/194282/215233/179275/2240.700

 

This can be easily modeled; the challenge is figuring out the duration increase from moving from 1.5 to 1.6 rockers - the duration changes slightly at all lifts when moving to a higher ratio -this will bump your HP peak up a few RPM, too. See the Engine Masters test between 1.5:1 and 1.6:1 rockers and pay attempt to the RPM of the peaks.

I found a "poor man's" calculation that will estimate the duration increase from switching ratios, but it's super crude and just assumes a straight line drawn from the seat-to-seat duration up to the new lift peak. Somewhere in the 1.5- 3 degrees range is probably pretty safe. I agree that the AFRs should like the extra lift.



Adam

 

I would like to see 20 hp. lol
Just 10hp/10tq all the way through the powerband would be nice.

People have paid more for less! Eek

R

 

A little context here guys about why I picked a .525 lift cam for my 355 L-82 with 219/225 duration and why the AFR 180's versus the 195's. I did much research on my own, spoke to the forum members who know about cam/head combos and then relied on my builder who did the bottom end for advice for further clarification.

Since I was going to have a 355, not a 383, and it was a street car only where I wanted good bottom end with maximum torque from 2,500-4,500 RPM and was not going to rev past 6,000 RPM and then very infrequently, I decided on the AFR 180's. The 195's have a benefit in the upper RPM's especially above 6,000+ RPM but would sacrifice some low end grunt versus the 180's. Thus the choice of the AFR 180's.

The Howard roller cam (.525/.525 lift, duration 219/225, LSA 110, operating range 1,500-5,600 RPM) was matched to the AFR 180's for good bottom end , Very strong mid range torque and very good HP up to around 5,800 RPM which it has in spades! I would have liked to go to .545 or .550 lift BUT the problem is that to find a grind with that much lift and moderate duration is almost impossible. I could find roller's with .550 lift but the duration was 235+ which will hurt the bottom end and midrange torque. This is an area where the 383 has an advantage since with the 28 additional cubes, one could go up to a 225/230+ duration with more lift than the 355 roller cam and not hurt bottom end power as much, which circles back to the 383 advantage versus a 355 IF it is built to maximize the cubes over the 355. Most 383's I read about or crate engines do not maximize this advantage which is why the typical street 383 does not have more power than the 355's built correctly for the street.

Also, a forum member who had an 78 L-82 who put on AFR 195's on the OEM L-82 350, not 355, with a howards roller cam with .501 lift was disappointed in the low and mid range power. He advised me to go moderate on the duration with as much lift as possible with the AFR 180's...thus the 219/225 duration and .525 lift Howards roller...it is spot on!

Lastly, the Roller tipped rockers are 1.52's since they were on the OEM L-82 by me in the 90's and I reused them for the 355.

I know this is blasphemy to say but with the AFR's, howards roller cam, 10.2 compression, and 1 7/8 inch Long tube headers on my motor, I am really not looking for more power...To me the C3 chassis with the power I have now is pretty much maxed out as total package...usable power, balanced handling, steering response, braking capability etc...bigger power levels would require substantial upgrades to these areas to be safe UNLESS all you are interested in doing is going in a straight line, again, my opinion.

I have a 10 C6Z06 when I want to go crazy fast with some level of safely........

Hope that helps!

 

Yes, and no. I think this diversion deserves it's own thread.

You obviously have amazing results for a refreshed L82 bottom-end, BUT there's more to the 350 vs. 383 story than just the cubic inch increase:

The move from 350 to 383 gives the cylinder a closer to an ideal stroke to bore ratio (closer to square) -minor change.

One of the big and underrated changes is that it increases the AVERAGE and Peak Piston Speed this speeds up the average FPS through the ports in the head and can increase average torque further. Average piston speed of a 350 with a 6,000 RPM peak: 3,480 FPM; max piston speed 3500: 5,717; Average Piston speed 383: 3,750 (7.8% increase). The max piston speed on a 6" rod 383 goes up 8% and a 5.7" rod 383 goes up by 8.5%. If you have slightly oversized heads, or don't spin to the max supported RPM of your heads for your displacement the increase in average piston speeds can actually see the increase in torque increase MORE than your starting ft lbs / cube. (BigJoe and David Vizard on SpeedTalk mention seeing a greater increase in torque with the move from 350 to 383 than the starting tq/cube ratio would imply.) -An AFR 180 head may be an exception to this rule as it is SO close to max velocity with the undersized minCSA already.

You also tend to get lower friction, thinner rings, better skirt profiles and anti friction coatings with good stroker pistons that can all help vs. maintaining a stock piston.


If going with a new rotating assembly for your 355 vs 383 build, it's a no brainer to go with a 383 as it's more power, same price. The real question is whether to recondition parts, as you did and save a ton of $$ as a trade off for a minor increase in power.


Adam