HOW TO: SBC POWER COMBOS

here's the question for today what kind of small-block Chevy should I build and test should it be a mild combo you know design for torque and towing how about a dual purpose street strip combo how about something even Wilder you know something you're gonna put slicks on really get after so which compost should I build what the heck let's do all three in this video we're gonna take a look at three different small-block Chevy combos the first one designed for torque production you know low rpm the second one dual purpose street strip combo something with a little more cylinder head and a little more camshaft the final one is our wild combination with a lot more cylinder head a lot more Camp Chef and a lot more rpm so what do all three of these combinations have in common well they all share the same sharp line let's check it out if things started we wanted to start off basically at the lowest form at the most at the least powerful most basic form of transportation this is a 350 as we talked about we did have forged pistons in the reason we put those in was because later on in the combinations we were gonna step up to fairly big camshaft so we wanted to make sure I mean the strength of the piston really wasn't the issue we wanted to make sure that we had enough piston to valve clearance so that we had valve reliefs and the Pistons to run big camshafts that's really the only reason that we upgraded it but you could duplicate this with any basically junkyard motor writer right out of the wrecking yard or one that you're rebuilding that you already have but to start off we put together this 350 we equipped it with us at a stock 882 smaug heads basically a stock hydraulic flat tap flat tappet camshaft and a two barrel intake we also installed the factory cast-iron exhaust manifolds and basically just ran exhaust out of the cast-iron exhaust manifolds back to the back with no no mufflers or anything so this is kind of your bare bones basic small-block Chevy with a 2 barrel intake manifold cast-iron intake manifold that a two barrel rochester combination two grown Rochester carburetor so equipped with that two barrel and the stock exhaust manifolds this 350 made 241 horsepower and 359 foot-pounds of torque as you can see torque numbers actually not too bad you know more than one pound foot per cubic inch was this is okay but the horsepower number not great for a small-block 350 I mean only gilt 241 horsepower that's not very much but that's the tuber manifold the first thing we did was install headers on this thing so on are very mild combination I would recommend headers even after you see the results here so after installing the long tube headers our power output jumped all the way to 248 horsepower now the games were not great with the long tube headers and that's because the rest of the motor wasn't in the position to take advantage of the headers long tube headers are definitely a good idea on any small-block Chevy unless you're trying to install them on this bone stock two barrel manifold or there's bones like two two barrel combination otherwise long tube header is definitely a good idea we'll see that as we go up in power so our next modification because we had a 2 barrel intake and nobody wants to run that here's what happens when you install a four barrel intake now this was a cast-iron Quadrajet intake with a factory Quadrajet so as you can see and not unexpectedly the the four barrel intake manifolds with the long tube headers are still made quite a bit more power the peak torque was up to 385 foot-pounds and peak horsepower was at 278 horsepower as you can see it gained power everywhere from below 2500 rpm it matched the 2 barrel intake so there's no game there there's no low speed power gain from there from the 2 barrel and just added more power through the whole curve so the next modification on our mild combination was to install a set of ported heads and a mild cam now what we did was install ported versions of the 882 heads I would recommend milling these which we didn't do it would be a good idea but we also installed a PE 246 basically an RV cam so this is a combination that would be go together for a guy that wanted kind of a 350 for towing you know we're kind of a street application as you can see the ported head and camshaft picked up power quite a bit even though it's a very mild cam it's actually in the missions legal camp too which is important to note 340 horsepower and torque was up to four hundred foot-pounds now you guys probably wondering well how much of this is the cam and how much of this is the heads actually the camshaft is probably worth twenty-five or thirty of this maybe and the remainder might be the cylinder heads now there's another option for this now I included the ported heads because if a guy already has accommodation and he wants to port the heads what I would recommend take the heads out port van port match them do the bull work and also mill them and you'll get some good gains so if you already have the heads that's a good option the other option obviously you could put aftermarket heads on it but if you want to go the inexpensive route go to the wrecking yard and get a set of vork tech heads now if you're gonna do that you also need a matching Vortech intake manifold and there's there are lots of those available even some inexpensive aluminum dual plane intake sit work with the Vortech heads so the Vortech heads will offer increased compression because they have a smaller chamber and they flow a lot better than a knee to head does also so if you run those you're gonna pick up power from compression you're gonna pick up extra flow just make sure that you have the valve spring necessary for whatever camp chef you're going to run on so this is a good combination and the final thing that we did with this this kind of you know milder towing kind of a combination was we installed an RPM air gap intake and a slightly bigger carburetor we installed a 650 Holley on this thing or this is a 650 demon I should say and the combination that rpm air gap and demon carburetor compared to the factory iron Quadrajet intake and Quadrajet carburetor picked up quite a bit equipped with that combination we made 360 horsepower and 416 foot-pounds of torque and as you can see there was basically just gain there was really no loss by going to that new intake manifold and carburetor combination so this is the mild combo we've jumped up using these modifications as described we've jumped up from like 241 horsepower to 360 horse so those are nice games but now let's take a look at what happened when we step up to kind of the middle-of-the-road performance upgrades after demonstrating all the modifications on the mild combination it's time to step up into something that's kind of a middle-of-the-road you know maybe more of a Street strip the other mild combination was good for like maybe towing and this is a good performance combination but not really all-out before we get to that we need to understand that we installed a set of aftermarket cylinder heads and a camshaft on this and upgraded obviously with with the original short block but it's important to note that no matter what changes you make and since there are 20 30 40 50 sets of different small-block Chevy cylinder heads available the heads that you put on the power gains that you get from those heads are gonna be dependent on the combination itself and what I mean by that is if you were to take a set of you know aftermarket airflow research heads that flow to 80 to 90 or even three hundred CFM depending on which one you pick that head will support over 600 horsepower but if you run it on a 450 horsepower combination and we compare it to say an inexpensive set of Chinese aluminum heads let's say for a small-block Chevy the gains that you get from the airflow heads might not be as great as they otherwise would if you had a serious combination where you're taxing both heads out so it's just important to note now on our combination we installed a set of holley aluminum heads and we also upgraded the camshaft but know that there are other heads that would do other things and you could certainly make more power and we'll show you what happens when you go up even farther in camshaft on the wilder combination and really want to make some power but here's what happened we installed our set of holley heads and a said of and I'll kind of give you an idea where we were so we started out at 241 horsepower and then with our ported stock heads and our four-barrel intake and aluminum intake we made 360 horsepower so here's what happened after we installed the Holley heads and a slightly bigger extreme energy 268 comp camp from Comp Cams and I'll go ahead and put the specs up here and again it was still a flat tappet camshaft because this was a flat tappet motor later on we're gonna step up to a drunk roller can we really go big but equipped with our holley heads and our slightly bigger cam the combination produced 418 horsepower torque goes up as well 444 foot-pounds of torque and as you can see even though we went up in camshaft and cylinder head we still made as much power down low at 2500 in see as the milder combination and basically just made more power everywhere which is always good now at some point we obviously will have to start trading power for a hint of the top-end gains for the bottom end but right now we didn't have to do that so this was a good combination and a good middle-of-the-road over 400 horsepower for you know for a small-block Chevy working well so now let's take a look at what happened when we step up even more in camshaft and cylinder head and intake now our small-block Chevy combinations we started out at 241 horsepower with the stock 2 barrel stuff stepped our way up to 360 horsepower after adding Porter heads a mild cam four-barrel induction system then we stepped up even farther a set of aftermarket heads any slightly bigger camshaft so the next step up from there was to install even more camshaft and a set of even better cylinder heads so what we did was install a much larger comp hydraulic roller cam as a retrofit can allow us to run a hydraulic roller in a non hydraulic roller block we also installed a set of airflow research 195 competition heads so the good ported ones we retain the Edelbrock rpm intake manifold but stepped up to a larger 750 demon carburetor so here's what happened when we made those changes to our combination and remember we had already modified our short block to accept this so this is why we installed the forged piston with the extra valve reliefs to allow us to run a bigger camshaft you probably could not run this camshaft in this cylinder head on a stock junker and short block because there probably isn't enough piston to valve clearance besides a flat top this and gives you a little extra compression and that's where we started with all of this so we'd run the same short block on all these combinations so equipped with our air flow research heads the 750 Holle and the bigger comp extreme energy cam the power output jump to 524 horsepower peak torque was up to 481 foot-pounds you could see this thing was now starting to make some fairly serious power it was a good combination and you know thanks to that forward piston who gave us the bow believed we could run enough camshaft in it now the interesting thing is if you look down low it didn't lose a ton of power I mean it's obviously this thing wants to run higher than the other combinations and it's making good peak power at the top but it didn't lose a ton of torque down low compared to the other combination so it would still work well as a dual purpose kind of daily driver but now what I want to do is get rid of all these other pieces here so it'd be easier for you guys to see because here's what happened when we made our final test so this was with our airflow research heads and the big comp cam now here's what happened after we swapped over from the dual plane rpm air gap over to a single plane Victor jr. with the same demon carburetor so equipped with the single plane which is probably a good combination for this because since we were making power out at 6,500 the single plane worked pretty well out there it made 541 horsepower so it was up quite a bit but as you can see and it's typical of a single plane and versus a dual plane intake test we lost a lot of low speed power with that single plane I mean we lost as much as 411 to 447 so we asked we lost like 35 foot-pounds there 4200 rpm so this is these are the losses inherent in that kind of trade-off yep you get a little extra power at the top but it does cost you down low so you got to decide whether or not it's worth it but remember the cool thing is that this was the same sharp line we ran very mild combinations a kind of mid-level street strip and then this kind of more racy combination all using the same short block as long as you have enough piston valve clearance with the valve relief in that flat top forms piston let's get to our conclusion ok guys what did you think about the build up of our small-block Chevy well technically it was 3 Chevy's the mile the medium and the wild combinations I'll tell you what I like like I like putting together a motor putting it up on the dyno and tuning it and finding out how much power it makes but what I like even more than that is putting a motor up and making changes to it I like finding out what the individual changes do so when we started it out with our combination it was a basic two barrel motor and it made 241 horsepower now using our cylinder heads camshaft and intake we were able to upgrade that to different configurations we went with our mild configuration that would improve torque it was a mild build up then we did our street strip then we did our wild combination and we varied the power output of that combination starting at 241 horsepower and we went all the way up to 542 horsepower so basically we changed the power output of this same basic short block by over 300 horsepower which is an impressive amount especially since we're only starting at 241 horsepower but it goes to show you whatever you start with you can make a lot of power you can make a little power or you can make somewhere in between are mature older guys thanks for watching make sure like share subscribe ring the bell I'll keep testing

Channel: Richard Holdener

Views: 136,898

Keywords: sbc, POWER, HEADS, CAM, INTAKE, AFR, EDELBROCK, HOLLEY, DEMON, DUAL PLANE, SINGLE PLANE

Id: NAuHAmzyEvw

Length: 14min 33sec (873 seconds)

Published: Tue Jun 16 2020