What do you think of this BB?

fladoans · Mar 14, 2006

I had been thinking of buy a complete BB crate engine until I saw an article in Car Craft about a 1000 hp BB. Now that engine had a super charger added, which I am not going to do and the block was a stock GMPP 454. I want to use the GMPP 502 short block with the following parts, please let me know what you think of this combination:

GMPP 502 - GEN VI short block, with 4.00” stroke forged steel crank and 4.47” forged pistons and forged rods.
AFR 315 CNC ported heads and then milled to 112cc cambers. According to them this should give me about 9.2:1 compression.
Crane CAM Hydraulic roller, duration 230-236 degress, .598/.610 lift, LDA 112 degrees
Crane 1.70 roller rockers
Edelbrock Air Gap Intake
Holley 850
MSD Ignition

The article used a Victor JR intake, but I want to use a dual plane intake for 2 reasons, to get it under a stock cowl hood and I want the torque lower in the RPM range.

So what do ya think, build this or buy a complete crate engine.
Thanks

67RS502 · Mar 14, 2006

I think I'd stick a cam in it, and a good single plane and it would fly

fladoans · Mar 14, 2006

67RS502 said:
I think I'd stick a cam in it, and a good single plane and it would fly

I could put a different cam in it, but unless a single plane can fit under a stock 2" cowl hood, that's not possible. I checked Edelbrocks web site and the height of the carb mounting plate for an air gap is 5.225" and for a victor jr its 5.80". It doesn't sound like a lot, but I've been told the victor jr won't fit. Any other suggestions? Thanks Steve

Larger Dave · Mar 14, 2006

I would go with the oval port heads unless you are going to take the RPM's up enough to use the rectangular port heads. With a hydraulic roller cam you're still within the upper limit of the flow characteristics of the oval port heads at 502 cid and 6000 RPM. Because of this you will get better throttle response and more overall torque, with a broader torque curve.

If you want to take advantage of the rectangular ports I would go with a solid roller like CompCams 296ER-8 grind 260°/268° at 0.050" lift; 0.714"/0.714" lift with 108° LSA (of course your leaving something on the table with 9.2:1 compression). Depending on how much you are going to drive this thing a flat top piston might be better than a dish, and save cutting the heads for later. Bump you up to 10.6:1 with 118cc chambers (ragged edge of pump gas friendly), and you wont have as much fly cutting to do for valve clearance.

Larger Dave

fladoans · Mar 14, 2006

Larger Dave said:
I would go with the oval port heads unless you are going to take the RPM's up enough to use the rectangular port heads. With a hydraulic roller cam you're still within the upper limit of the flow characteristics of the oval port heads at 502 cid and 6000 RPM. Because of this you will get better throttle response and more overall torque, with a broader torque curve.

Dave that's something I wondered about. This car is not going to the strip very much, it is a weekend crusier more than anything else. I would like a loppy idle (love that sound), but it still needs to idle. I'll do a some more research. Thanks Steve

Larger Dave · Mar 14, 2006

The stock ZZ502 cam is actually quite noticeable. It is about as long a duration as you can have and still have any vacuum. It is weak on lift, IMO, and runs out of steam around 5800 but will easily rev to 6200. I like the looks of the 572 cam but it might be a bit much for a 502 on the street (The bigger the engine the less you notice a big cam).

Larger Dave

Chevy-SS · Mar 15, 2006

Yeah, do your research. It's a challenge to find that "Goldilocks" combo, that has good power, nice sound, lopey idle (that we ALL like) and is still pleasant to drive on street.

It's easy to make big power, but not so easy to make it streetable.

Now here's an engine that looks streetable and makes serious power: http://www.bankspower.com/twin-turbo-engine.cfm

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fladoans · Mar 15, 2006

Yeap thats a real nice engine. I could probalbly just buy a stock ZZ502 engine and add a supercharger to it and make 600-700hp easy. I have a truck with a supercharger on it now and I have a 70 chevelle with a 396 in it. I just like the way the old fashion BB sounds and feels.

I've been looking at cams most of the day and I have so much info I'm confused again.

But, still working.

Chevy-SS · Mar 15, 2006

Hey, I forgot to mention. If I was you I'd think seriously about getting a cam with the 4/7 lobe swap. Rumored to produce slightly more power sometimes, but not always. However, the thing that really intrigues me is, it's supposed to be a little smoother-running with less noticeble vibration and less wear on rod and crank bearings.

Lots of varying opinions on the 4/7 swap, but I'd try it just to have the potential of a smoother engine...........

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Larger Dave · Mar 15, 2006

The biggest difference between the 550 horsepower of the ZZ502 and the 550 horsepower of L-88 427 wasn't the cam but the compression. A hemispherical head engine (the big block is a semi-hemi or half round, half flat) makes serious power in the 15:1 compression range (much more so than a wedge shaped small block would of the same cid).

It (the hemi) is based upon 1930's aviation engines that were utilized to good effect in WWII not in aircraft, but in tank engines made by Cadillac and Ford. Chrysler revisited the design when they slapped a set of hemi heads on their 413-426 max-wedge engine and cleaned up in NASCAR and NHRA. The rest as they say is history, at least up until '71 when lead free fuels were mandated for cleaner air.

The rumble you remember from the L-88, L-79, LS-5 engines was the result of man hole size exhaust valves allowing some very heated gas out into thin wall tube headers. That is what I love to hear as well (real race cars do have doors!).

The best of both worlds requires that you live in a state that doesn't enforce pollution restrictions through annual inspections (like Florida), and that you have the disposable income to spend $5.70 a gallon for race gas; then you can have a modern hot cam, and 15:1 compression. Failing in that build a large cubic inch displacement engine that lives with your allowable compression ratio (9.2:1 max) with available pump gas. That means no long duration lumpy cams, which bleeds off what little static compression you have.

Larger Dave

fladoans · Mar 16, 2006

Thanks guys. All these suggestions are exactly what I needed. Based on what I've learned here's my plan of attack. I have 2 options, 1 - A ZZ502 short block, AFR 290 aluminum oval port heads and milled some to help bring up the compression a little, a voodoo cam with duration at .050 241/249, .625/.625 lift on 110 LSA, a performer Air Gap manifold and a Holley carb. Still not wuite sure of size 850 or 950 cfm and MSD igintion. Or option 2 , is to completely build the motor, probably starting with a 454 4 bolt main block, bore and stroke it and use basically the same parts above, except as Larger Dave recommended maybe use a different piston and not mill the heads. I have not finished pricing this option out yet, although it should be cheaper. My goal is to get a streetable engine that runs on pump gas and has close to 600 hp and 600 ft lbs of torque.

greg moreira · Mar 16, 2006

Although the AFR is advertising oval ports.....you aint gonna see any for some long time(unless something just recently happened). They have been advertising these things forever....but even still, Tony at AFR will tell you that they are a long time coming.

Those 315 CNC heads are EXCELLENT EXCELLENT EXCELLENT! They flow huge numbers through a relatively small port(380ish cfm), and have good enough street manners. The biggest problem...those heads really like some valve lift to do what they are capable of. Honestly, those things really get cracking with .680 or better valve lift. Granted, you dont need all that much to make great power.....but if your going to go way less....you dont necessarily need to go with heads quite as good as those(you wont utilize them all that well with a fairly small duration/lift camshaft). Lemme give you a few examples of AFR headed engines similar to yours(in displacement). Ill start some new threads and post the combos and results....and from there, Ill annotate a little.

greg moreira · Mar 16, 2006

Ok, here is one combo with the smaller 305 heads.

AFR 305 CNC chamber heads
Comp roller 260/266 at .050, .677/.687lift, 110LSA
Brodix HV2001 manifold
Holley 1050 Dominator
2" hooker Comps
9.4:1 CR, pump gas
701 hp @ 6300
620 ft lbs at 4800 (very flat curve)
Probably less hp in the car....full exh and an engine driven fan.

So far a best of 10.23 @ 130.8 in a 3500 lb car.

Streetable, but rather lumpy.

Thats a solid roller cam, not a hydro roller. Also, note the relatively low compression. These big motors dont need tons of comp to make huge power. Although I do beleive that motor could have gotten away with more for sure and still ran on pump gas. But with numbers like that, why bother(with a lot more compression) unless your really trying to maximize the effort.

greg moreira · Mar 16, 2006

I dont know if you know who Mike Lewis is, but this is one motor you see him bring up all the time.

AFR 315 CNC heads, Vic Jr, 1"spacer 850 Demon, Comp roller 254/260- .698/.666-111 sep, Isky Red Zone solid roller lifters(VERY GOOD LIFTERS), 9.80 compression, 2" dyno headers
670HP@ 6300 @ 610ft lbs @ about 45-4600.
Over 500 ft lbs from 2900.
Idled about 850, don't remember the vacuum
This was on a dyno considered pretty conservative as well.
Also this engine was pulling over 2" of vacuum from around 5000 on up which means the carb was too small.
Add about 1 point of compression and a little more carb & I have no doubt it would have gone over 700 honest HP.

Thats a street killer for sure! Little tamer than the first, and still not that radical(look at the RPM's both of these engines make peak horsepower at). Its pretty low considering the large "appearing" camshaft. Cubic inches have a lot to do with making a cam look small.....plus, the modern stuff with tighter seat durations help as well(like what is in both of those engines).

All Im sayin is to really take a hard look at what kind of camshafts really work well in the kind of caliber head you are considering. If you think you want to go milder...no prob. I just dont see it being quite worth it to buy excellent heads, but then run a smallish cam that doesnt totally utilize em. If you dont plan to upgrade later, but a bit of a smaller and cheaper head thats still every bit capable. The 305's are the biggest Id go if your going much smaller on the cam. Or another AWESOME out of the box head are the smaller brodix race rites. It dont matter whether its the 270 ovals or 290 rectangles. Both ports act about the same and flow very similar(350ish). They just enlarged the openings of the oval port head to accomodate a rectangle opening(which increased the size), but all in all....its the same port and all and they act real similar. You could use a set of these with compression numbers like your planning, compression similar to what you want, and a roller of say 248/255 degrees and low .600 lift on a 110-112LSA and get good results(Id still guess 580-600 horses) on pump gasoline. I personally would not go any smaller than the voodoo cam you mentioned.

Oh and by the way, if AFR did actually release the big block ovals....look at em pretty hard! The smaller rectangles are all awesome and streetable heads, and Im sure the ovals have got to be great(cause they have been thinking about them forever).

fladoans · Mar 16, 2006

Greg, thanks for keeping up with this. I did some more reading last night on chevelles.com and I also found a couple of comments about the AFR Ovals not being made yet, but I am going to call them this morning. I will also check into the brodix race rites heads today. On your 2 examples of the engines I can see that both are a little more than I need (but not much more), but I like where the torque is made.

Okay using your 2 examples, I could come up with a combo that probably exceeds my needs but would be a really nice engine:

AFR 305 CNC chamber heads
Comp in upper 9's (mill the heads or different pistons) - Still pump gas
Hyd Roller CAM with a duration somewhere around 250/260 duration - .Mid to upper .6/.6 lift and 110 - 112 LSA.
Air Gap Manifold
Holley 850
MSD ignition
2" Headers
and probalby be over 600hp around 6000 RPM and close to 600ft lbs around 4600 RPM.

I know the AFR heads are rectangle ports, and more than 1 person has said I don't need the rectangle ports, but I am just using the examples below that make fantastic power.

I had only a couple of absolute requirements (must be a streetable BB, must fit under a stock 2" cowl hood and must run on pump gas) and the rest was attempting to make the best combination from there, within a reasonable bugdet.

How's that look?

Thanks again for all the help.

What do you think of this BB?

fladoans

67RS502

fladoans

Larger Dave

fladoans

Larger Dave

Chevy-SS

fladoans

Chevy-SS

Larger Dave

fladoans

greg moreira

greg moreira

greg moreira

fladoans

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