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AwesomeAuto and others hit the nail on the head. Don't overthink it. You'll drive yourself nuts. Whether its a Summit Pro LS truck swap or turbo cam, BTR/LJMS 4.8/5.3 turbo cam, or whatever inexpensive Elgin grind often mentioned on this site and sold on Ebay; you're going to make power. When you think you have your mind wrapped around best possible split, LSA, lift, etc you'll see someone successfully run a cam totally opposite of that and blow "conventional wisdom" out of the water.
I know any out the box cam these companies is offer will get me to my power goals, hell stock cam will get me there but it'll be less stress for the motor and less boost to make the same power. Just was wondering what people were running as I see talks about the triple 12,ss2, lil John motor sports, and tick performance. The ss2 has a nice price point and since its a fun car and I'm not out to break records or win money it seems good for my project. Just getting opinions from others before pulling the trigger. I cam from the sr20 world were everyone runs the same cam pretty much. Thanks for everyone's input. I'll think on it, still haven't bought anything except trunnion upgrade and pac1218 springs.
People are running every imaginable cam under the sun with many making power so you'll get a plethora of different answers and opinions. There's little "magic sauce" to the junkyard turbo LS world at this point. Look at the LS9 cam. Wide LSA, sub .580 lift, easy on the valvetrain. People put cars in the 8's with that cam after spending $125 bucks on one. Easy to tune, great driveability, cheap as hell. Others talk crap about the cam, some with valid points about "Yeah it works, but how much better would a custom or dedicated turbo cam be!!".
As mentioned any of the mild aftermarket cams will work well... prob arguing about 5-15hp difference at diff rpm ranges between most aftermarket stuff. (between the diff grinds not total power gained) So not a life/death choice here.
I've run 4 different cams in my 4.8's. Each had something I liked about it...
1.) Issky triple 12 was prob the best all around. Didn't sound aggressive tho.
2.) The Edelbrock 2215 had lots of low end and sounded choppy like a big mean cam, It wasn't! lol. Def woke it up down low if thats what your after (not my thing)
3.) Howards version of the GM hot cam. Less aggressive than the 2215 but still chops a little. Had more mid range, less bottome end. But basically the same as the Edelbrock on the butt dyno.
4.) Summit stag2. Isn't very aggressive sounding, which I was surprised about, but makes the most top end power out of the few cams I'd run.
I really like how texas speed lets you choose the tighter LSA on some of their cams. Feel like people run WAY to wide of an LSA on the 4.8's. No reason not to run .600 lift IMO. I like the texas speed stg 2 or 3 on a 110 LSA. (id go tighter if it was an option and u weren't concerned about idle quality.
That David Vizard fella states there is basically 1 LSA that will work best for any given motor for peak power output. And its determined by valve size and cubic inches. Of course this is throwing things like idle quality and cruise quality out the window. Not to mention back pressure from turbos etc... He would pick the LSA first, then adjust the valve O/C points to suit the RPM range. His articles are pretty interesting. And if you watch Richard Holdner at all he just tested the same cam ground on 3 different LSA's, results were in favor of the tightest 108 LSA. .
Too bad he doesn't rev his engines out or give them any real boost. Running a 4.8 or 5.3 and being limited to 6500RPM is missing the point to me, especially in a SBE setup. I agree the Summit 8706 cam works well, and I've turned it well above it rated 7000, its seen 7800 for a few months along with some Summit dual springs and my oil looks as good as ever.
800whp is a stout goal for a stockish 4.8 with a 78/75 IMO. Your talking 900ish crank. With an engine that makes 350 or so NA. That means your looking at 25ish lbs of boost assuming about 20-22hp per pound with that T4 setup. All just an estimate, but you want to stay sensible with the goals and parts involved. You won’t hit anywhere near that goal on pump gas IMO. A lot of chassis dynos read high too. When they dyno 1000whp and trap 150 at 3200lbs the numbers don’t add up. A true 800whp goal is very stout. Not really a street car…or even useable on the street or track without traction management and/or a kick *** suspension setup.
As mentioned they will all make power, you just need to decide where you want it to “shine” most power band wise. And also keep in mind that big boost on a T4 makes big back pressure. That will kill the power made per pound. Also overlap comes into consideration much more at high back pressure levels. I’m a fan of advanced cams with tight centerlines. Check out squirrel racings record holding 4.8 cam specs! They are pretty dang tight for someone revving it out to 8400 lol! He’s on a 111, +5* advanced
This was my 220/220 @ 111. .510 lift on a 4.8. It was great, but would have benefitted from a 110 or 109 and .600 lift in my opinion.
800whp is a stout goal for a stockish 4.8 with a 78/75 IMO. Your talking 900ish crank. With an engine that makes 350 or so NA. That means your looking at 25ish lbs of boost assuming about 20-22hp per pound with that T4 setup. All just an estimate, but you want to stay sensible with the goals and parts involved. You won’t hit anywhere near that goal on pump gas IMO. A lot of chassis dynos read high too. When they dyno 1000whp and trap 150 at 3200lbs the numbers don’t add up. A true 800whp goal is very stout. Not really a street car…or even useable on the street or track without traction management and/or a kick *** suspension setup.
As mentioned they will all make power, you just need to decide where you want it to “shine” most power band wise. And also keep in mind that big boost on a T4 makes big back pressure. That will kill the power made per pound. Also overlap comes into consideration much more at high back pressure levels. I’m a fan of advanced cams with tight centerlines. Check out squirrel racings record holding 4.8 cam specs! They are pretty dang tight for someone revving it out to 8400 lol! He’s on a 111, +5* advanced
This was my 220/220 @ 111. .510 lift on a 4.8. It was great, but would have benefitted from a 110 or 109 and .600 lift in my opinion.
the 700 to 800whp is my end goal, of course not right not with it being stock heads and bottom end. There have been some that reached this goal on a stock cam, and motor but of course how long will it last is the question. I'm assuming 600 or so right now and I know pump will only get me so far. I have everything in for e85 (1500cc, dual 450s, hobb switch) but don't wanna swap unless I have to as there's only 1 gas station in my area. I could always shot meth too.. But the reason I posted it for my goal is because I don't wanna buy another cam in the future when i do swap out rods, pistons, and heads. Hope this helps. I am not trying to run this motor to 800 as is.
If you want to buy once for your goals that’s the wrong turbo. And if you want the cam to “maximize” your gains at 800whp, it won’t be ideal for the backpressure monster turbo you are running now at 600whp. The turbo you have now is great for 600ish hp and will spool decent and make for a fun ride. But you can’t “spec” a one size fits all cam that will be happy with that turbo and the turbo and backpressures needed to make 800hp the most efficient way possible. U Can def stab a cam that will “work” in there. And if that’s the goal, toss a SS2 cam in and call it a day. It’s the cheapest option… save your money for turbo and fuel system upgrades.
700-800 is easily done on the stock heads and stock bottom end. The record holder made 1300ish on stock untouched heads and a stock bottom end. Put your money in the turbo and the fuel system, add boost until your goal is reached. Setup a flex fuel sensor and run a capable ECU. E85 and high boost is the easiest route. A cam only GEN4 SBE block is plenty capable and pretty reliable at 700-800whp. My current 4.8 setup has stock heads, stg 2 summit cam, and runs 20lbs of boost through the big t6 S480. Traps 156 at 3000ish. So around where your wanting power wise..
If you want to buy once for your goals that’s the wrong turbo. And if you want the cam to “maximize” your gains at 800whp, it won’t be ideal for the backpressure monster turbo you are running now at 600whp. The turbo you have now is great for 600ish hp and will spool decent and make for a fun ride.
I agree. A buddy of mine managed to run 9.44 @ 14x with a cast gen 1 7875 in a 4000 lb volvo with a 4L80e, but I've been telling him for a while now that his turbo is maxed.
The gen 2 billet 7875 has a 1.25 A/R turbine housing and is good for another ~200 HP over the cast gen 1. I would consider that one for 800whp.
If you want to buy once for your goals that’s the wrong turbo. And if you want the cam to “maximize” your gains at 800whp, it won’t be ideal for the backpressure monster turbo you are running now at 600whp. The turbo you have now is great for 600ish hp and will spool decent and make for a fun ride. But you can’t “spec” a one size fits all cam that will be happy with that turbo and the turbo and backpressures needed to make 800hp the most efficient way possible. U Can def stab a cam that will “work” in there. And if that’s the goal, toss a SS2 cam in and call it a day. It’s the cheapest option… save your money for turbo and fuel system upgrades.
700-800 is easily done on the stock heads and stock bottom end. The record holder made 1300ish on stock untouched heads and a stock bottom end. Put your money in the turbo and the fuel system, add boost until your goal is reached. Setup a flex fuel sensor and run a capable ECU. E85 and high boost is the easiest route. A cam only GEN4 SBE block is plenty capable and pretty reliable at 700-800whp. My current 4.8 setup has stock heads, stg 2 summit cam, and runs 20lbs of boost through the big t6 S480. Traps 156 at 3000ish. So around where your wanting power wise..
I have a billet 78/75 right now and I think my injectors (1500s) and fuel system (dual 450s) is there for the 800whp. So I just need to upgrade turbo to bigger and switch to corn. And any decent cam around 600 lift and 220-230 dur with 109-112 lsa
I have a billet 78/75 right now and I think my injectors (1500s) and fuel system (dual 450s) is there for the 800whp. So I just need to upgrade turbo to bigger and switch to corn. And any decent cam around 600 lift and 220-230 dur with 109-112 lsa
Sounds about right! The billet wheel alone won't do it for you. The main bottle neck is the baby T4 housing. Not a lot of info and testing out there with the GEN2 78/75, but they seem pricey. I'd jump straight into an S400 based unit, they are proven. If your stuck on the T4 thing, they have a 1.25 T4 with the 96/87mm exh wheel. 76mm compressor is plenty. Proven to well beyond your goal and about the same price.
As far as the CAM goes, the tighter you can go on the LSA the better in most cases IMO. DOubt you'll find any "shelf cams" tighter than 110 to suit your needs anyway. The tighter you go the more "chop" at idle as well. If you want it to idle like glass and be a daily cruiser the typical STG 1 shelf cams will all do that in my experience.
Sounds about right! The billet wheel alone won't do it for you. The main bottle neck is the baby T4 housing. Not a lot of info and testing out there with the GEN2 78/75, but they seem pricey. I'd jump straight into an S400 based unit, they are proven. If your stuck on the T4 thing, they have a 1.25 T4 with the 96/87mm exh wheel. 76mm compressor is plenty. Proven to well beyond your goal and about the same price.
Actually a decent amount of testing from what I've seen, even some back to back tests over the "Gen 1 78/75". Multiple people have done north of 850whp with the baby T4 1.25 Next Gen 7875 on 5.3's and over 900whp on 6.0's, not hateful for a $650 T4 knockoff turbo.
Originally Posted by AwesomeAuto
I agree. A buddy of mine managed to run 9.44 @ 14x with a cast gen 1 7875 in a 4000 lb volvo with a 4L80e, but I've been telling him for a while now that his turbo is maxed.
The gen 2 billet 7875 has a 1.25 A/R turbine housing and is good for another ~200 HP over the cast gen 1. I would consider that one for 800whp.
Same I ran 9's with a 7675 and baby .96 T4 with a heavy *** car. I've also ran the Next Gen 7875 1.25 and it does seem to work very well for its size. I recently gave the VSR billet 80/82 T4 1.10 a try as I couldn't pass it up for $650 and it drops in place of the next gen 7875 but has a slightly larger 82/87 turbine wheel. Its plenty responsive and easily runs sub 5 second 60-130's on the street.
Actually a decent amount of testing from what I've seen, even some back to back tests over the "Gen 1 78/75". Multiple people have done north of 850whp with the baby T4 1.25 Next Gen 7875 on 5.3's and over 900whp on 6.0's, not hateful for a $650 T4 knockoff turbo
Not talking trash on the 78/75. Its a great unit.But for 900ish crank I think there are better choices out there for similar $. Also don't believe T4's belong on any LS, but I understand the bolt-on appeal with common kits.
Maybe I’m looking at the wrong turbo? There are 3 78/75’s that I see. The cast, old style billet (assuming that’s what the OP has since it has the smaller T4 housing) , and new “NEXT GEN” billet with revised “S” compressor wheels. Those are $750-790 and have larger compressor and exhaust housings too. That’s what I thought we were talking about. They are physically larger, like the S400 stuff. And I believe a CAST T4 S475 would give it a run for its money. Esp the 87/96 unit in a T4 housing.
I’d love to see a comparison between the big/small turbine wheel S400 stuff And the “next gen” 78/75. My point is if your paying $750-790 for a turbo… go with the proven performer. I’ve yet so see any back to back tests against S400's. If you know of any, let me know! A cast T4 S475 is a damn capable unit. And the billet S476 with the 1.25 T4 and 87/96 wheel was a nasty combination and what I'd suggest. Viren can setup any of those. My T6 S480 is $748. IT spools just fine on a mild 4.8 with a 2" divided hotside and is making the desired power the OP is wanting at about 20lbs. Trapping 156 or so at 3100lbs.
Last edited by Forcefed86; 04-16-2020 at 01:29 PM.
Not talking trash on the 78/75. Its a great unit.But for 900ish crank I think there are better choices out there for similar $. Also don't believe T4's belong on any LS, but I understand the bolt-on appeal with common kits.
Maybe I’m looking at the wrong turbo? There are 3 78/75’s that I see. The cast, old style billet (assuming that’s what the OP has since it has the smaller T4 housing) , and new “NEXT GEN” billet with revised “S” compressor wheels. Those are $750-790 and have larger compressor and exhaust housings too. That’s what I thought we were talking about. They are physically larger, like the S400 stuff. And I believe a CAST T4 S475 would give it a run for its money. Esp the 87/96 unit in a T4 housing.
I’d love to see a comparison between the big/small turbine wheel S400 stuff And the “next gen” 78/75. My point is if your paying $750-790 for a turbo… go with the proven performer. I’ve yet so see any back to back tests against S400's. If you know of any, let me know! I’d put money on the S400 stomping it pretty handily. A cast T4 S475 is a damn capable unit. And the billet S476 with the 1.25 T4 and 87/96 wheel was a nasty combination and what I'd suggest. Viren can setup any of those. My T6 S480 is $748. IT spools just fine on a mild 4.8 with a 2" divided hotside and is making the desired power the OP is wanting at about 20lbs. Trapping 156 or so at 3100lbs.
Last time I saw a T4 billet Borg S476 that actually performed it was like a $1,600 turbo, I would hope it would outperform a $600 knockoff. Yes the VSR 78's are $750 on the website but you can get them elsewhere a good bit cheaper, like ebay I made an offer of $600 and they took it. The Next Gen turbo is also a good bit lighter than a Borg, think mine was only 25lbs.
What "spools fine" to one person may not be that great to another. I've had turbines from 75 to 111mm and most often with an impromptu rolling street race the smaller turbine car jumps out and the big turbine car plays catchup the whole race, if it even hooks its impressive on paper peak power. I agree the larger turbine car will ultimately make the most peak power on a dyno and trap higher at the track, but the smaller turbines often make more power under the curve and makes a street car more fun to drive.
156MPH at 3100lbs is only about 850whp, I've made more than 850 on a T4 flange so it doesn't seem the T6 is really doing all that much for you, especially on a 4.8L. I would absolutely say if the goal was over 1000 or on a larger engine T6 is the way to go (or twin T4's) as its very easy to make 1,100+hp at that point.
Thanks for everyone's help. I appreciate it and the knowledge you have given me if I plan to upgrade later on. Once I get it running good I'll post the track times. Pic for reference of the truck
Last time I saw a T4 billet Borg S476 that actually performed it was like a $1,600 turbo, I would hope it would outperform a $600 knockoff. Yes the VSR 78's are $750 on the website but you can get them elsewhere a good bit cheaper, like ebay I made an offer of $600 and they took it. The Next Gen turbo is also a good bit lighter than a Borg, think mine was only 25lbs.
What "spools fine" to one person may not be that great to another. I've had turbines from 75 to 111mm and most often with an impromptu rolling street race the smaller turbine car jumps out and the big turbine car plays catchup the whole race, if it even hooks its impressive on paper peak power. I agree the larger turbine car will ultimately make the most peak power on a dyno and trap higher at the track, but the smaller turbines often make more power under the curve and makes a street car more fun to drive.
156MPH at 3100lbs is only about 850whp, I've made more than 850 on a T4 flange so it doesn't seem the T6 is really doing all that much for you, especially on a 4.8L. I would absolutely say if the goal was over 1000 or on a larger engine T6 is the way to go (or twin T4's) as its very easy to make 1,100+hp at that point.
And I’ve owned and ran all the turbos I’m speaking about as well. We can speculate on HP all day, I’ve seen 3k lb cars dyno 1000hp on T4’s and trap 140’s as well. I said it’s making about the power the OP was requesting and it’s a $748 proven turbo/combo. I don’t see any 4.8 78/75 cars running 156 at similar weights and boost levels? I’m not saying they don’t exist, but I’ve never heard of one. Or making anywhere near 800whp at 20lbs? Yet, how many S400 based cars do we see doing it?
Because you managed to score a $750 turbo for $600 once (which I’m jealous of!) That doesn’t mean it’s a $600 turbo. If we can’t all get the same deal every time, it’s not really relevant! I’m sure you could find “deals” on an S400 framed turbo as well.
You’ll only make so much power per pound on a 4.8. The best and cheapest solution is to run a lot of boost, so you don’t want a lot of back pressure. The 78/75 will tap out well before an “big wheel” S400 and have tons more back pressure. Its why the record holders run retarded huge GT55 based singles or big twins. As far as the T6 S480 goes, it isn’t exactly taxed at 20lbs on a tame 4.8. I’m sure I can run 30+lbs with this unit and still make great power per pound. That’s not happening on a 78/75 IMO.
I see 1.4:1 back pressure at 20ishlbs with the S480 T6. My T4 S475 was seeing 2.8:1 trapping 153 and basically made diddly for power at higher boost levels. So it’s pretty clear to me the advantage of the T6. Also worth noting is I ran a 2.5” hotside with my T4 setup and my current 2” divided T6 gets up on the converter more quickly. I’ll happily line up and roll race with my lag monster T6. I have to pull tons of power out of down low. The last thing any turbo LS I’ve ever been in needs is more power below the curve… I’m pulling tons of power out of the 4.8 to get it plant a drag radial from a roll on the street. I even pull power at the track… You’ll only plant X amount of power below 40-50mph no matter what you do. Esp in a big heavy truck like the OP has. Last thing I’d want personally is some baby turbo wacking the boost gauge to 15-20lbs in a half second at 3500rpm. But again, ask 10 people get 10 different answers.
Last I asked, Viren will make a 1.25 T4 to the 87/96 wheel S4XX. Last engine in my car was a 6.0 with a china S476 with a machined 1.25 T4 for the 87mm wheel. Great unit! Was more like $900 when finished. It basically performed similar to the T6 S480 at like boost, but it had greater back pressure.
04-15-2020, 08:02 AM
