eagle275

open to all suggestions.

crate motor -
http://www.edelbrock.com/automotive_...etec_435.shtml


these are the heads - (would AFR's be better? - if so, which ones?)

http://www.edelbrock.com/automotive_...perf_rpm.shtml


any thoughts on an 800cfm quadrajet?


Thanks for all your help.

TheSkunkWorks

You might elaborate as to how much more power you're looking for, where you'd like it to come in, and what you're using it for if you want more than general suggestions as to what's "better".

That said, AFR 195's are quite good, but IMCO you could use a little more compression too; say ~10:1. Are you open to angle milling your heads, existing or new?

austinseanchris

I installed AFR eliminator heads on mine and whew, what a difference. 10.5:1 compression rate with a 180/58cc head. So many possibilities though with a 350. The most common motor in the world. I went with Edelbrock performer intake, MSD ignition, Hooker super comp headers. Depending on the year, I'd yank all that egr/smog crap off the motor as its nothing but a power drain(that is if its a 75 or newer model). Once I pulled that junk off alone, it was like a different ride. Change your cam, add roller rockers, underdrive pulleys, throw a 3.70 under it, etc...the list goes on and on my friend...That's what I've done to mine and it makes right at 300hp to the wheels as opposed to the 175 hp factory rating ughh. But most of those are pretty cheap upgrades...that is, if you can get past the $1800 for the heads, lol. Next step for me is more carburetion and bigger cam.

billla

These discussions always need to start with budget. All decisions flow from that simple number.

TheSkunkWorks

Yes it does. I (we) often overlook that little item.

eagle275

I have the cash to do a good bit. I want 500-600hp, and stay on pump gas(93 octane) if I can. If not, I want as much as I can get and still use 93 octane. The way the oil thing is going, I might have to buy a cave and a horse and buggy. Anyway, thanks for the tips! Open for more information!

eagle275

I am open to that, definitely! Can I run on 93 pump gas @ 10:1?

TheSkunkWorks

Rather than simply giving you a fish in lieu of a fishin' pole, here's a primer on theoretical Dynamic Compression Ratio (DCR) that should help you get a better handle on this (includes a handy calculator you can download)...

http://www.empirenet.com/pkelley2/DynamicCR.html

...but take note that actual DCR is static compression ratio (SCR) x volumetric efficiency (VE%) at a given RPM. The above is only a reference, however much value you get out of it. Also, the more radical the cam/SCR combo, the more margin I'd leave. For instance, my ~10.3:1 solid roller, aluminum head, pump gas 427 BB will be landing at about 8:1 DCR.

chiefbob

I don't think I'm hijacking this thread, as I was about to post the same exact question.

Budget: ~ $2-3K

1978 350 L48 stock

Looking to increase HP to around 250-300.

My initial intention is to get rid of the cat and go true dual exhaust. Without going nuts on mods, is it possible to do this on my budget (after I change the exhaust out)? Also would need to pull all the air pollution stuff out.

Not looking to race, just want more zip in that old 350.

Thanks!

Bob

billla

Let's back up for a minute. You want to buy/build something from scratch, or you're trying to top an existing 350? I assume the former, but I wanted to ensure we're all on the same page

If you're really seeking 500-600 HP on pump gas, you're looking at a 12-15K+ build. Is that within your budget of "a good bit"? This will be a large-displacement, aftermarket block, large AFR heads (more than 195's) and associated forged rotating ***'y along with a roller cam.

Frankly your best approach given that power level is a supercharged LS-series build-up and swap to get something very streetable AND with those power levels.

billla

You're on the right track - headers and a free-flowing exhaust combined with even a mild top will get you there. A Vortec top with the right cam will get you in the 330+ HP range VERY inexpensively...

Don't forget about rear-end gears and/or torque converter...

Billysvette

Or supercharged 350

Attfay Elleybay

502 cid.

eagle275

Thanks! I'll research that.

eagle275

Here's the engine and heads - crate motor -
http://www.edelbrock.com/automotive_...etec_435.shtml


these are the heads - (would AFR's be better? - if so, which ones?)

http://www.edelbrock.com/automotive_...perf_rpm.shtml


any thoughts on an 800cfm quadrajet?


Edelbrock Crate engine:

PERFORMER RPM E-TEC 9.5:1
435 HP & 435 FT/LBS TQ

Specifications
Displacement: 350 c.i.d.

(4.000" bore x 3.480" stroke)

Horsepower: 435
Torque: 435
Compression: 9.5:1
Block: New "ZZ" 4-Bolt 1-Piece Rear Main Seal
Crankshaft: Forged Steel
Pistons: Hypereutectic
Camshaft: RPM Hydraulic Roller #2204
Rocker Arms: 1.5:1 Roller
Manifold: RPM Air-Gap Vortec #7516
Cylinder Heads: E-Tec 170 #60979
Carburetor: Thunder Series AVS
Water Pumps: Victor Series Aluminum
Distributor: MSD Pro Billet
Valve Covers: Cast Aluminum
Finish: As-Cast, Polished, and EnduraShine
Warranty: 2 Year/Unlimited Mileage
CLICK HERE TO VIEW DYNO GRAPH

The Performer RPM E-TEC 435 is the ultimate 350 cubic inch small-block Chevy for muscle cars, street rods and trucks. Qualities include: 100% brand new, GM ZZ short block with forged steel crankshaft, powdered metal rods and hypereutectic pistons, Edelbrock E-TEC 170 heads, RPM hydraulic roller camshaft, roller rocker arms, RPM Air-Gap intake manifold, Thunder Series AVS 800 cfm carburetor and optional water pump. Customers have their choice of standard cast aluminum, polished finish or EnduraShine finishes and water pump style.


Heads:

Performer RPM E-Tec 170
Performer RPM E-Tec cylinder heads feature an LT1-style raised runner intake port design for increased air-flow and ultimate performance. Available in 170cc or 200cc runner size, they both feature high-quality stainless steel intake and exhaust valves, 64cc combustion chambers and high flow intake and exhaust ports. The high-velocity Intake and exhaust runners are hand blended in the bowl area and the intake entries and exhaust exits are cnc profiled for increased air-flow. A unique combustion chamber design positions the spark plug closer to the center of the cylinder, promoting uniform atomization of the air/fuel mixture for more efficient combustion resulting in more power. These heads include adjustable rocker stud and guide plate set-up for use with adjustable rockers or washers to properly position the stud height to accomodate factory style self-aligning rocker arms. The casting is manufactured of A356 aluminum and heat treated to T6 spec for superior quality. An extra-thick 5/8" deck and Heli-coil threaded inserts offer improved durability. RPM E-Tec heads are dual-drilled to accept 1987-95 centerbolt and/or 1986 & prior flange mount valve covers. RPM E-Tec cylinder heads are available fully assembled and ready to bolt on or bare for use with your own valve train components. Made in USA.


Cylinder Head Specifications

Combustion chamber volume 64cc
Intake runner volume 170cc
Exhaust runner volume 70cc
Intake valve diameter 1.94"
Exhaust valve diameter 1.55"
Valve stem diameter 11/32"
Valve guides Manganese bronze
Deck thickness 5/8"
Valve spring diameter 1.46"
Valve spring maximum lift 0.575"
Rocker stud 3/8"
Guideplate Hardened steel
Pushrod diameter 5/16"
Valve angle 23°
Exhaust port location Stock
Spark plug fitment 14mm x 3/4 reach, gasket seat
Made In USA


Technical Notes: Sold individually. Requires the use of hardened push rods. Bare heads will have valve guides and seats installed, but will require final sizing and valve job to match the valves you will be using. To use stock stamped steel rockers on small-block Chevy heads, +.100" longer than stock Edelbrock pushrods #9629 or equivalent are required. Small-block Chevy heads may not be used on engines with less than a 4.00" bore except with camshafts with less than .450" valve lift. Vortec style intake bolt-flange requires vortec 4-bolt style intake manifold

billla

Still confused; you're buying a 435HP crate motor that you want to upgrade to 500-600 HP? No. Financially, I don't understand why you'd take this approach over buying an engine that makes the power you want, or doing a smart buildup from a shortblock such as SHP's 400 CID shortblock or many others.

At those power levels, it's not just about bolting on another set of heads and/or a new cam. It's possible to bolt together around 450HP or so, but beyond that it takes real design work to hit those kind of targets. I've only done a few that were even close...and in all of them I got a few surprises

You're asking what kind of heads...when you should be asking what design it takes to get to 550 HP...

eagle275

No, I purchased it about 2 yrs ago. The engine doesn't even have 500 miles yet, the car is in paint, etc. Had I known then what I know now? Anyway, you've made some very good points! The block is a ZZ4 block. I was wondering what I could do with this motor to get more out of it. I would love to sell it, and do something else like you are talking about. This has been a total resto. Origional engine was stolen many yrs ago when i had it in for rebuild. That's another story, but I decided to move past all that and do what I wanted. Anyway, talking about design, can you elaborate more? I've had this car for 26 yrs, 2nd owner. And from what I'm reading, you guys know alot more than I do on this! LOL! Fighter jets and 18-wheelers are my specialty. I have really learned a whole lot on this resto, and taken tons of pics, which will be cataloged, etc. Thanks for all the input!


BTW, I have Hooker Headers 2134-1HKR - Hooker Super Competition Headers, Full-length ceramic coated, 1 3/4 in.

billla

OK, this helps a bunch. Sorry to hear about your loss of the numbers-matching engine, but as you note it takes that originality burden away and provides a whole new universe of options

The heads/cam are definitely the weak spot on the engine. The E-Tec heads are decent, but still only flow about 240/180 @ .500. The cam is an interesting grind, and at .539/.549 lift and 234/238 duration is very well-matched to the heads. The good news is that it's a roller, which is ideal in every way.

It's possible to use flow numbers to very roughly estimate HP. We start by taking the intake flow and adjusting it for the intake used; the RPM is a decent dual-plane, but reduces actual flow by about 20%. 240 CFM *.8 = 192 CFM Then the rule-of-thumb formula is .257*CFM intake*8 cylinders = 394 HP...which I suspect is a lot closer to what this engine actually makes sitting between the frame rails vs. on an engine dyno.

At these power levels, IMHO the dual-plane isn't going to cut it - even a decent one like the RPM...but anything much taller isn't going to fit under the hood. The question becomes what will fit in a single-plane, and I have to think it's a pretty short list (other folks chime in here).

If you're really looking for the most power you can get from your existing shortblock we're limited IMHO to around 500 HP max on a stock block and hypereutectic pistons. There are folks that push this and get away with it, but the risk goes up pretty exponentially. Given that the ZZ4 runs bolts vs. studs, you're pushing it already

The initial recommendation of AFR 180's or 195s with a single-plane if you can fit it and a cam upgrade would be where I'd go. AFR 180 Streets make around 260/207 CFM @ .500, and this gets us up into the 425 HP range with a dual-plane and 480 or so with a single-plane. You could likely stick with the existing cam with those heads. Frankly, that's about as far as I would go given your shortblock. The AFR 195 Streets would *require* a single-plane and cam upgrade IMHO, but would put you a tick over the magical 500 HP mark. I think you'd end up breaking it...

This was kinda rambling, but I was just kinda thinking and typing...

eagle275

Hmmm...single plane - which brand would you recommend? Also, I've got an L-88 hood from Eckler's that has 4 1/8 in clearance, or 4 3/8in, or 4 5/8in. I'll have to look. But it clears good. I had to go with that because the LT-1 hood would not clear. BTW, do you think the single plane would be too much hp? Don't want to bust up a good engine, LOL! What about the 800cfm qaudra-jet? I have an 800 Thunder Series Edelbrock on it - that's what Edelbrock put on it. Cam brand, etc.? BTW, thanks again for all your input!

eagle275

would a 383 stroker kit, etc. be feasible with any of this? Just looking at the endless options.