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So many styles of heads and cams! Elgin is my choice of cams but head's are tricky!! Seen several with 170cc to 210 cc chambers and most have the same valves! Looking for torque not horsepower!! Any feedback would be appreciated! Went to have heads rebuilt but one is cracked!!!
 

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Only head worth it, if torque is the goal, is AFR 165 with 58cc chambers.

With the right cam, you'll see over 400 ft/lbs.

At 10.5:1 CR, with a comp 35-512-8 roller cam and edelbrock intake, and these heads, my 94 was desktop dynoed at 340hp / 475 ft/lbs
 

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Ditto what @[U]BigBlue 94[/U], said. You want the velocity in the ports to be high at lower Rpms for Torque, the more cfm the head flows the more the torque curve shifts to the right (higher rpms). There's more to it but that is the basics of it.
 

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Only head worth it, if torque is the goal, is AFR 165 with 58cc chambers.

With the right cam, you'll see over 400 ft/lbs.

At 10.5:1 CR, with a comp 35-512-8 roller cam and edelbrock intake, and these heads, my 94 was desktop dynoed at 340hp / 475 ft/lbs
my 94 5.8 is running strong, rebuilt ~40k ago. Could I bolt on new heads and intake, then drop a cam in and be done or is there a bit more to it? I have MAF conversion kit, just not fully installed yet. If I could be around 300hp/425tq neighborhood I think I would be happy. It beats saving up for a stroker kit with my budget.
 

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Well it all depends on what you plan on doing with the Engine, but if it's still tight (good compression), no noises, good oil pressure at idle and not burning oil you should be ok to go with Heads, Cam and Intake at 40K miles. The heads should add the most and cost the most, followed by the cam, etc....
 

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I had a lengthy reply typed but it disappeared when I hit submit. Gotta get some work done. I'll type it up later
 

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So, when building an engine, thebfirst thing to pick is the basic cam profile. I.E. RV, street, hot street, race, etc. With MAF, you can choose basically any cam and tune the ecu for it. The speed density system is not the same. It is rather finicky on what specs it wants to see from the cam.
  • lobe seperation of 114° or above
  • intake centerline 110°
  • duration @.050 no higher than 220°
  • valve lift of no more than .510"
Comp cams 35-512-8 falls within those parameters. 35-514-8 also does, and is slightly more aggressive. Both will need a tune to really run good. Especially if you change compression, add heads, etc.

@kammots you can indeed drop a cam, heads, and intake on. That's essentially a top end kit.

For a 351, the edelbrock truck intake is the best bolt in unit. A lightning intake is great too, but rare and as pricey as the eddy intake.

AFR and TrickFlow make the best heads bar none. 165cfm runners are best for low end torque. 200+ cfm runners are for racing and dont make the low end torque. They move the powerband up in the rpms, and boost top end power.

Speed density also doesnt want to see more than about 10:1 compression. This also brings up the point about high compression and higher octane fuels. Rule of thumb is at 10:1 you need to be using 91+ octane to keep from premature detonation. The higher the octane, the slower it ignites. However. The real factor is cam choice. This gets brings in the second kind of compression ratio: Dynamic. The normal number quoted for compression is the Static compression ratio: simply figured by cylinder (and head) volume at BDC divided by the volume at TDC. Keep in mind that the combustion chamber is actually itself plus the area inside the head gasket and any space left between the piston at TDC and the top of the block.

Dynamic compression is what actually determines what octane you can use. It takes into account valve timing along with the static compression, and is what the engine ACTUALLY sees. The formula is not simple and best referenced elsewhere: Wallace racing has a good online calculator. For instance, my 300 has a static ratio of 9.75:1. I had three cams chosen that were all very similar. The dynamic ratio varied between 7.3 and 7.7 to 1. For the 300, its magic DCR number to run on pump gas (87-89) is 7.5. My DCR is 7.47 and it does indeed run well on 89.
 

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appreciate the replies. Looks like I need to gather $ then do some more research as my goal is 87 octane, smog legal in CA and a hefty bump in hp/tq.
 

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Best way to do that is with some boost... you could find an eaton supercharger in the old thunderbird supercoupes. Eaton M90 and M112 are pretty common to adapt to a wide range of applications. Or go procharger if you win the lottery
 

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I thought boost required higher rpms to kick in, interesting. I'm not handy enough (yet) for pulling from a Tbird and making it work. Lottery, I may have to bet on that for now. =) Thanks for the ideas, all this goes in the file for when I eventually talk to some builders.
 

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I thought boost required higher rpms to kick in, interesting. I'm not handy enough (yet) for pulling from a Tbird and making it work. Lottery, I may have to bet on that for now. =) Thanks for the ideas, all this goes in the file for when I eventually talk to some builders.
No no no. Think about a turbo diesel. They top out around 4000rpm.

A supercharger makes boost any time the engine is running. It spins the same speed, relative to the engine at any given rpm. So if the engine is spinning 1000 rpm, the SC is spinning 2000. At 2000 engine rpm the SC spins at 4000, and so on. Differing the SC pulley size will change this ratio, for more or less boost.

Turbos are a different animal. They arent directly connected to the crankshaft (with a belt). They rely on exhaust pressure to spin up and create boost. So boost is variable with rpm. My 96 powerstroke made 5-8 psi when just cruising, but mash the skinny pedal and boost went up to 25-28 psi. Decreasing the size of the up-pipes feeding exhaust to the turbo will increase pressure. But that's a tradeoff for evacuation of exhaust gasses. Smaller turbos spool up faster, but dont produce the boost that a larger one will. So sometimes you see a small one feeding a big turbo. There is A LOT of variables to building a turbo system. I know of a 2003 mach 1 with a 281ci (might be stroked to 312) engine making over 1000hp with a pair of turbos. Stock was 305hp and mine would still break the tires loose at will. Coking is a major issue with turbos if they arent lubricated in the proper way. Exhaust also gets really hot. My powerstroke would see EGTs of 1200°. I'm not sure where turboed gassers get up to.

For most purposes, a supercharger is the way to go because they are more reliable and offer boost at all rpms.

For ease of installation, a centrifugal supercharger is best on SBF engines. A roots style can be done, but the pulley snout and distributor fight for space. The eaton superchargers i mentioned usually mounted to the side of the engine, since they generally were on EFI vehicles and not constrained by a carburetor mounting system. They require a lot of legwork to install since they were never put on a SBF.

Boosting an engine usually requires lower compression to run right. 7.5-8.5 to 1 is ideal. And different cam profiles. This is compared to a normal naturally aspirated engine where power comes from more and more compression.
 

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Flat top pistons and a 62cc head also works nicely. ~10:1 any decent aluminum head is an upgrade.
 

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Years ago my boss and his son built a mid to late 80's ranger with a 5.0 swap. They took eBay headers and mounted them upside down and welded T4 flanges on and then put a pair of small t4 style eBay turbos on it. Truck was fast and the engine itself was stock.

Not sure what they did for fuel system but I do recall they did something with the temp sensor to trick the computer into thinking it was always cold which richens the fuel mixture.

I only looked at it because they wanted $2000 for it and the truck was fairly clean looking. I didn't care for the turbo set up and decided to just buy an 86 Mustang GT.

Point of that was turbos can be done to sbf easily. But like I tell my sons: when it comes to performance there is cheap, powerful and reliable. Pick any two because you can't have all three
 

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Aluminum heads, cam and intake on a 351w will make a huge difference. Any heads from AFR or Trickflow. On a 351w I'd run at least the AFR 185cc or Trickflow 170 11r which flows similar to the AFR. On the 351w the intake manifold is the next big restriction and the Edelbrock piece for trucks is nice but spendy.

Or talk with someone that does porting about having the factory opened up. I've heard there is a lot of material on the factory and it can be opened up to flow pretty well.

Next is cam, as mentioned cam is huge to power curve. Low duration and high lift, 112-114 lobe seperation are good for low end and good idle. There are several off the shelf cams that would work well. I reccomend spending a little extra and going custom cam. Tell cam designer exact parts you use and your goals and they'll design the cam for your build.

With a custom cam, you can go bigger on heads and intake without losing much lowend and leaving room to upgrade later.
My 347 uses Trickflow 205cc 11r heads and a factory 5.0 truck lower ported to the max (opened up to a 1262 gasket and welded on each runner to add material and shape ports) flows around 300cfm per runner on the lower. These parts would often be called too big for a torque build but having the cam designed for the parts keeps the torque curve low. My combo should make about 400hp and 450 ft lbs. No dyno numbers yet motor only has about 70 miles on it. Hopefully in the next few months I'll get it tuned and hard numbers.

Bumping compression helps a lot as well. With aluminum heads 10:1 static is a good pump gas target.
 

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@[U]smeans92,[/U] you stated: My combo should make about 400hp and 450 ft lbs. No dyno numbers yet motor only has about 70 miles on it.

So my questions are: 400hp at what RPM? 450 lb-ft at what RPM range? Definitely not in the Lower RPM range and a 347cid putting out 450 lb-ft of Torque!!!!!!!!
I'd like to see the Dyno sheet on your setup when you finally get it.
I'd also like to place a bet on your Torque curve being skewed to the right with those 205 heads and the hogged out manifold. Low-end Torque needs Velocity in the runners and ports to create the Torque.

@[U]Tom 351[/U], "Looking for Torque not Horsepower."
AFR 165 heads (with a reasonable compression ratio), a good cam profile, Manifold, the right Throttle body all port matched with Long tube headers will give him all the Torque he could ever want short of more cubes or forced induction. You can skimp on the Long tubes and replace them with Shorties for ease of installation and cost but you will loose power all along the curve, but you'll still have what you are looking for "Low-end Torque". All the components MUST match each other and play in harmony. You don't want to mix and match the components. That goes against the "Theory of Fluid Dynamics". FACT!!!!
 

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I used the AFR165s on a 351 at 10.5:1 compression with a 114 LSA cam. Desktop dyno gave it 475 ft/lbs at 2000rpm, 400 @ 3500, and 350 @5000. I used the published AFR165 flow data, though mine had been ported for a single season of race use. In a 347 built to run 150mph in the 1/4 mile, in a fox body Capri, the 165s made too much torque and not enough high rpm horsepower. Too much tire spin off the line and not enough oomph after 1000'. That's why they went to a 200cfm head, and I got a deal. The porting was done by the 70 year old racer/mechanical engineer with his own professional flowbench. That 351 was a screamer, even hampered by the stock tune and injectors. With an e4od, 4.88 gears, and 37" tires, it had a nine second 0-60 time. For an 8 foot tall, 6000 pound brick, that's pretty impressive. Hell I dont think my 300 horse superduty will move that fast, with 4.10s and a 6 speed.
 
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