JUNKYARD 4.8L & 5.3L POWER UPGRADES! ADD 130+HP

if we replace the head cam intake on a 4.8 liter how much power is it worth let's nuts up there let's run the same test on a 5.3 in this video we ran a stock LR for 4.8 liter up on the dial then we replace the heads cam and intake so how much power was that worth because one test isn't good enough we perform the same test on the larger 5.3 liter along the way we also snuck in an intake guess lots of good stuff so check it out for this video we actually had a pair of test motors a 4.8 liter lr 4 and a 5.3 liter LM 7 on the 4.8 liter lr 4 we first ran it stock up on the dyno meaning stock head stock cam stock intake and everything else was stock on this motor the one exception to both of these motors is that we ran them with the Holley HP management system long tube headers and without accessories now our upgrades on the motor included heads cam and intake on the 4.8 liter we installed a healthy crane cam 590 lift to 24 to 32 degree duration split and 114 degree lobe separation angle actually both motors shared that cam upgrade the other thing they shared was the intake upgrade we installed a fast LS XR t intake and 102 millimeter throttle body on both the 4 8 and the 5 3 where the two motors differed because these motors were run separately and not together was the cylinder head choice now for the 4 8 we installed us at a ta ported stage to 706 hits on the v 3 we installed a set of TFS 205 hits now the reality is on these two motors those two heads were all but identical we know because we've compared them back-to-back and they both work very well in fact those two heads on those combinations were probably a bit of overkill because those heads will support way more power than either one of these combinations mate it's not because the heads don't work we just didn't have enough motor under the heads to really tax them so let's start off by taking a look at the power gains offered on the 4.8 then we'll follow that up on the larger 5.3 ok guys here are the results for the 4.8 liter lr4 this is in stock trim and this 4.8 liter we freshened up from the junkyard made 333 horsepower at 5300 rpm and 343 foot-pounds of torque at 4700 rpm now the question I usually get is why does it make 333 horsepower when the 4.8 liter is rated so much lower than that by the factory the reason is because we run this motor in a different configuration than the factory does when the factory rates that power output it is with all of the accessories all of the air intake the complete factory exhaust system and with the factory tuned so that's how they rate the motor and that's how they test it now we don't do that on this test when we ran this thing on the dyno it was all stock meaning stock throttle body intake manifold heads cam Shore block all of that but we did run it with no air intake so just an open throttle body we also ran it with an optimized tune which is much better than the factory tune and we also ran it with no accessories just an electric water pump and in this case inch and 3/4 long tube headers so that's why this 4.8 liter is making more power than a factory rated number but as we said 333 horsepower of 5300 rpm and 343 foot-pounds of torque at 4700 rpm so let's do pretty well but now let's take a look and see what happened after we made our modifications namely the ported cylinder heads camshaft and the fast intake manifold got a big jump in power all the way up to 476 horsepower at 7000 rpm and 392 foot-pounds of torque at 5900 rpm so both peak horsepower and peak torque increased as we see here and most of the gains are at the top of the rev range as we see don't don't worry about the stuff down 2,000 rpm on that for eight we loaded it that way down there because we were doing other testing on some real mild camshaft on and on stock headers and things but as you can see most of the gains from the mods came way out there but we did pick up a hundred and forty three horsepower total and about 50 foot-pounds of torque so it was a good upgrade so now we're gonna take a look at because one of the questions I always get is yeah but what about the fast intake that's expensive what happens if we just run the truck intake so we're gonna take a look at that in just a second so I want to cover one of the most common questions we get is especially on this 4.8 liter because there are a couple but we're gonna deal with the intake first so we ran this with a fast SX RT and there's confusion there about whether the LS XR t is for a truck or a car like the LS XR and really that's more of a fitment issues both those manifolds actually produce almost identical power curves one is not designed for a low rpm truck application this LS XR t is not designed for a low speed truck application they both make power up high they just have different plenum volumes and a little different runner entry but otherwise when I've tested them back-to-back a number of times they always seem to produce about the same power curve but the question now is what happens if we run this head and cam combination on the 4/8 with the stock truck intake manifold which I have here because we did do that before we put the fast on and as you can see the fast definitely does make more power if we put the stock truck and this is an early truck and not a TBS s it made 452 horsepower at 6,900 and 388 foot-pounds of torque at 5,500 slowing us down from 5500 out past 7000 with the stock truck intake compared to the LS XR t with the TBS s intake you probably would be right in between those two because the the trailblazer SS works really well especially on this for 8 in my opinion that's probably a good way to go on the 4:8 the other thing I wanted to mention is on this 4:8 because it's so small and and the power outputs not tremendous you could probably could get away without having full cnc ported heads because i mean let's face it those cnc ported heads from total engineer flow work great and they have the potential to make a lot of power but we're only using 450 460 470 horsepower worth and the problem is well it's not a problem you can get there with the factory head so what i would recommend on a 4:8 is don't spend the money on a full-blown set of cnc ported heads and it's something you can do yourself take the stock seven oh six or eight sixty two heads mill them a bit and then do a little hand work maybe open the chamber up a little bit do a little bowl work little cleaning up and i think you could probably get most of the way there because you don't need a 600-horsepower set of heads on the motor that's only making 450 you can get there with a stock stuff so now that we've taken a look at the four eight let's jump over and see how the five three did now let's take a look at the same test run on larger 5.3 now we can take a look at the power gains offered by replacing the heads cam and intake on the 5.3 liter in stock trim run just like our 4.8 with headers open throttle body electric water pump and no accessories the 5.3 meter produced 344 horsepower at 5200 RPM and 378 foot-pounds of torque at 4,300 RPM now I need to cover one thing this is about the lowest power output that I've seen out of these stock five threes normally they're about ten horsepower and ten foot pounds above this this was a used junkyard motor or so in this case we kind of get what we get but just know that this is a little bit lower starting point normally they're in the mid 350 range 355 or so and like 385 foot-pounds of torque when we start off with them and I've run dozens of dozens of these and this particular one just seemed like it was a little on the low side so if we take a look at what happens when we run the upgrades now remember these aren't exactly the same upgrades as we did with the four eight that wasn't the this test we were just doing heads cam and intake on both of the motors of different displacements it turns out that they were very similar same camshaft same LS XR t intake and but on this motor we used the Trick Flow 205 heads which are really going to be very very close in power to those te a 706 heads but let's take a look and see what happened when we made the modifications this is the heads cammon and intake and the fast intake equipped with that combination the 5-3 made 484 horsepower at sixty seven hundred and four hundred and twenty four foot pounds of torque at fifty seven hundred and had this thing started out where the rest of them do I think we would be a lot closer to the 500 horsepower level and this thing work out really well just like the 4:8 so now again your question has got to be okay what about with the factory truck intake and something interesting happened there so we're going to cover that in just a second so just like with the four eight before we put the LS XR t intake on the five three we also ran with the factory early truck intake so we can see it produced 484 horsepower with the LS xrt and that picked up that was a hundred and forty horsepower gain with the heads cam and intake over the stock five three but if we compare the factory truck intake to the LS XR t we see again the the fast manifold made more power from 5500 on out but interestingly enough on this five three for some reason the factory truck manifold made more power down low and I we normally don't see that on the fast I mean maybe at the very bottom but usually they're very comparable through most of the curve until the top and then the fast picks up a ton at the top and usually a little more of this than this on the five three the fast manifold is usually worth more over the factory truck manifold and the Trailblazer SS as we go up in displacement and power so if you do that test on a four eight it's not worth as much if you do it on a five three it generally worth more if you do it on a six oh it's worth even more the wilder the combination is the more that manifold seems to be worth but on this on this particular test this is what happened I mean the airfield was spot on and the timing was spot on so I'm not sure but this is what happened so that's what I'm reporting now that we've run this test I can talk a little bit about this 5/3 just like with the four eight I think it's possible that you could get near these power numbers with just home porting your stock 706 heads and if he went with especially in this case if you went with a trail blazer SS intake I think you'd be right near these numbers I think at this 5/3 was right that with this combination of the poor did hit the trick flow heads which I really liked the 205 heads on that small bore and the fast intake and that camshaft I'm sure that we could get near 500 if everything was right and maybe a little more than that if we ran that other comp can but I like to put in these things that's that 54 454 dash eleven that's a 227 intake duration and English we could push this thing over 500 horsepower which would be nice on a 5/3 so now let's get to our conclusions okay guys what do we learn from this test well the first thing is there's a ton of power waiting to be unleashed in a 4:8 or a 5/3 but you know what that's not the only thing I want to bring up an important point the combination as I ran on the full rate and 5/3 here are not the ultimate combinations they're not the best in fact I want to know what you guys have done what kind of combinations have you guys put together that have made good power let's start off with a cam chef now in this combo I ran that crane cam but again it's not the best camp it's not the only cam what about you guys what do you think what's your go-to cam for like a daily driver what's your go-to cam for a street strip combination like the one I tested here or what's your go-to cam for a full race combination what about the cylinder hit we ran CNC ported heads on both these combinations but you know what I think we can get the same kind of power with a little hand party stuff you guys can do at home if you were to take a set of seven oh six or eight 62 Ed's mill them do a little chamber work and a little bulwark I think you get the same results what about the intake I know the fast intake is really good for power but it's also kind of expensive I think we can get the same power with a trailblazer SS especially on the little 4.8 what do you guys think what's your go-to intake is that the Trailblazer is the stock truck does anybody step up to the fast let me know make sure to LIKE share subscribe ring the bill do all that stuff make sure to comment let me know what you guys think and what do you think should we run boost on these now thanks for watching

Channel: Richard Holdener

Views: 159,251

Rating: 4.9372091 out of 5

Keywords: junkyard, cheap, LS, turbo, NA, LR4, LM7, 4.8L, 5.3L, TFS, TEA, crane, Holley, westech

Id: cMMPRls__-U

Length: 13min 58sec (838 seconds)

Published: Thu Jan 16 2020