How much HP would heads alone add?

Discussion in 'Engine Topic' started by Crowsville, May 24, 2013.

  1. Crowsville

    Crowsville Member

    Jan 13, 2013
    New York, New York
    Can people chime in on this? Would adding headers/exhaust system, and an intake offer more of a noticeable difference than heads, intake and rockers first?
  2. rockheadrocks

    rockheadrocks Veteran Member

    Just a quick note: in the interest of simplicity, you can always combine steps 1 and 2, and 3 and 4. Combining steps 3 and 4, and even step 5 makes a lot of sense, since you have to take off the intake to swap the cam anyway.

    The basic reasoning behind the order is this: it doesn't matter how much airflow you get into the engine if you can't get it out.
  3. Damon

    Damon Veteran Member

    Nov 16, 2000
    Philly area
    I'll put this as plainly as I can, then I'm punching out. Heads are where the power is. This has been true since the dawn of time. A good rule-of-thumb is that 1/3 of your total engine budget should be spent on the cylinder heads. I regularly spend as much as HALF my budget on them. They are the only part you can buy that can build power pretty much everywhere (assuming you buy appropriate heads for your application) with no downside, other than their cost.

    You can add headers and and intake to your current engine and it'll pick up some ponies, but probably not anything like 50HP. They mostly help "upstairs" in the RPM range, where peak power happens. Compared to even stock manifolds connected to a decent flowing dual exhaust, the gains will be minimal on a stock low compression engine.

    Your engine has two main restrictions right now. Compression (too low) and head flow (not enough). By changing from your stock 76cc heads to 64cc Vortecs you address both problems simultaneously. Compression is at least raised at out of the basement where it is now to a slightly more reasonable 9:1 (that helps with torque production considerably and overall improves engine efficiency) and you get a LOT more flow from Vortecs than you will with old smogger heads.

    Bigger cams are fine for making power, but not unless you have the head flow to support them and the rest of the drivetrain is ready to work in a higher RPM range, where they make their power. With a stock stall converter and 2.73 gearing the LAST thing you want to do is trade away bottom end torque for more peak HP. You could pick up some power by swapping cams but you really can't go much bigger than stock before you start to see some noticable "trade-offs".

    Your stock "pickup truck" cam specs in about 192/201* @ .050 on a 112* LSA with lift of about .390/.410. With the low compression, crappy heads, stock stall converter and tall rear gears the biggest cam I'd recommend stepping up to would be something like the base Edlebrock Performer cam (AKA Summit K1102) which specs in at 204/214* @.050 on a 112* LSA and lift in the low .400" range. That isn't a big change. Sure, it will help, but you're just going to yank it out and throw it in the trash as soon as you build the motor you REALLY want later on down the road. It would be a throw-away item to spend money on, basically.

    Additionally, your old motor mat not be happy for long suddenly spinning to 5500-6000 RPMs if it spent its entire life below 5000 up to this point. That's when stuff breaks. Old parts don't often like trying to be taught new tricks until they have been properly machined and built to support that RPM level.

    Vortec heads are fine up to about 400HP. They would work very well as a no-trade-offs upgrade from your stock smogger heads. A head swap is easy to do in your driveway with no special experiance or tools (other than a torque wrench). PLUS they have enough flow to support you up to about 400HP. In other words, they are NOT a throw-away part. You can use them over and over again as you build progressively more powerful motors.

    I should mention that what I'm saying about Vortecs also applies to just about any entry-level 64cc performance SBC head (cast iron or aluminum- they all work WAY better than your stock smoggers). I'm not a Vortec groupie, it's just that in this case you are ready to buy a different intake anyway, so buying a Vortec-style intake is no more or less expensive than buying an intake for standard bolt pattern heads, so it's a wash in that respect. And stock Vortec heads can be had for CHEAP- typically much cheaper than an equivalent set of aftermarket performance heads.

    Please note that I recognize you are thinking in at least 3 different directions on what to do next. What I am answering is the QUESTION YOU ORIGINALLY ASKED. If your goals change on this project then so might my recommendations.

    Your original goal makes perfect sense. And if you go that way I think you'll like the results if you take my suggestion. However, if your goal changes, then the plan forward changes. So be sure the goal you are aiming at.
    Last edited: May 26, 2013
  4. hutchenc

    hutchenc Veteran Member

    Aug 21, 2007
    Damon's right...heads are where the power is at. Vortecs aren't the best head out there, but they're the best bang for the buck if you can find 'em used.

    Start looking on Craigslist for a set. Or call a few junkyards and ask for a set of heads for a '96 to 2000 Chevy truck with a 5.7L motor. These heads are all over the place and for a used set, I don't think I'd pay more than about $250 becuase you can buy a new set for $600.

    It looks like you're from NYC so here are a few that took me all of 3 minutes to find.

    With any used set of heads, you should have them checked at a local machine shop before you put them on. You don't want to do this twice if you don't have to so it's money well spent.

    Or look for a good used pair of standard SBC aftermarket heads like Edelbrock Performer RPMs, Dart SHP 180's, .

    Like these (guy even has a matching intake and it comes with rockers):

    Or these (not a great deal, but not a bad one either):

    You have a lot of options locally. Just keep the intake ports small (in the 170 to 180cc range), get some small combustion chambers in the 64cc area, and you'll have a good mannered street car. I wouldn't buy a used flat tappet cam can pick up a new cam and lifters for about $150 no problem.

    As far as the exhaust goes, as long as you have a dual exhaust, I wouldn't worry about it a lot at your power levels. A set of headers isn't gonna get you that much power with a small cam. It'll help yeah, but I wouldn't focus on it.
  5. hhott71

    hhott71 R.I.P 11/19/18 Lifetime Gold Member

    Mar 30, 2001
    Joplin Mo. 64801

    I had a performance engine built for the street when I was 18. I had it all 625 AFB #1406, Torker (X shaped one) 10:1 comp 327/350 HP cam, Z28 springs, 2.02/1.60 valves. 11" converter Headers with 2.5"exhaust and Turbo mufflers.
    I had the stock 2.73 gears.
    My motor sounded good idling through the Sonic etc.

    My little bro had a 72RS, A pristine car my dad buys for him at 15 yrs old.
    At 16 we have headers and a Pro-Stock (brand) intake on it and I don't recall the carb. We added headers and exhaust. Well at 16 he blows it up. So dad buys him a new Targetmaster engine (choices were limited in 78-79 or so) with the aformented power goodies in place. He was slower than me of course. We'd leave even and I'd pull away, as my converter helped get my RPM's up on the line.
    Well Little bro gets a 3.42 posi swapped in his car for $150 and then proceeds to wax my ass all the way through first gear. I finally started pulling on him when I got past 3500 rpm which was a long time coming. I'd finally pass him near the top of 2nd gear.

    GEARS is the biggest performance maker.
    That an CU Inches, put a stock 400 in your car and it'll scoot a lot better from the extra low end TQ and the extra HP as the rpms build.
    Gears multiply TQ and allow the engine to rev to its HP peak quicker.
    Be it a stocker or HR motor.
    I had at home a 4.10 posi in my 70 12 bolt.
    I swapped rearends later that month. Lil bro only saw tail lights.
    Last edited: May 27, 2013
  6. Crowsville

    Crowsville Member

    Jan 13, 2013
    New York, New York

    Damon, you are awesome. Thank you, everything has come full circle.
  7. Crowsville

    Crowsville Member

    Jan 13, 2013
    New York, New York
    As for everyone else thank you, I had a feeling this was going to be a very complex thing to address in these forums but I now have a better understanding on what needs to happen so I can "complete" my car. Everyones two cents really did allow for me to see the bigger picture and what I really should have asked initially is what is the best thing I can do so I can build on it and have a well rounded vehicle.

    I always try to buy things for the long haul and if I could spend an extra hundred or so on a particular item that will last me years, I'd do it. Vortec Heads really do seem where its at. I think that getting it at a Junk Yard/Craigslist best suits me. At first I thought buying everything brand spanking new would be the way to go, but I could use the cushion on money and buy a nice intake manifold, valve covers for them as well as maybe even the set of rockers speed addict suggested earlier on.

    An exhaust system is what I plan to attach immediately after. Right now I have my headers merging into one cherry bomb glasspack - that's it. I want a true dual exhaust and that's going to be the very next thing I tackle. After these two a rear end is where I'm going to have to really put together some cash and do effectively. This is something that is going to require me more than likely opening another can of worms because I know there's LSDs, Detroit Lockers, Full Time Posi or something... from what I read LSD is definitely way to go but again, let me handle this first then I guess I'll address that when I get there.

    All that's left now is making this happen, I'll post pics and tell you guys what I think of the upgrades. Until then!
  8. Rich Schmidt

    Rich Schmidt Veteran Member

    Mar 27, 2010
    Denville NJ
    If you already have headers,you could spend $225 and buy the Summit brand(or Jegs) full dual exhaust in any size you want,with the turbo mufflers too. I would go with the 2.5" kit,and $30 in for a set of "Header Buddy" reducers because they are a great addtion to any system,and will give you room to grow. I would wait until you have all the parts to do the work. Everything is much easier in one step. Adding a cam after the engine is bolted back together means taking half the engine apart again. I would run a cam like the above mentioned Edelbrock cam which seems to me to look like the same "brown bagger" Sealed Power cam that you can buy for about $60 on Ebay. Add a double roller timing set,and the cam will work with the stock Vortec springs,but I would probably stick a shim or two under the used stock springs just to be safe. I would disassemble the heads,and clean any carbon off the ports and off the back side of the valves because it is practically free to do and is worth power. A cheap valve spring compressor can be had for under $25 and a stack of .030" shims for just a few bucks. You will have to buy a Vortec intake,but you can probably take your time and look for a used one on the internet. You need a Performer type dual plane intake,and many guys upgrade as time goes on,so the entry level stuff is more often available. You could probably do the whole job at once for under a grand and get a big power boost too. I would buy all the parts by shopping slowly and looking for the best deals,and not just buying the first parts that come along,and let the parts sit until you have everything from the gaskets to the spark plugs and even the oil before you make the change.

    Good luck.

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