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Hello everyone, I purchased a junkyard 5.3ls and fully rebuilt it. I called several of places regarding the cam, because I'd like it to be running very choppy, and I was advised to go with the Big ***** Thumpr Cam, well... Now I'm not sure if this cam was a good idea. In the future I'll be definitely boosting this thing but for now, I'd like to run it NA. My main concern is whether or not this thing works fine and will be drivable. It will be bolted up to a 2001 f-body t56. It's still not too late to remove the cam. I got this cam for free from a friend, and since it was advised to me, I took it and slapped it in. I just wanted to apologize for my lack of knowledge, I'm very fresh to this.
Engine rebuild parts list : LSXR 102mm intake & throttle body
862 heads
Ls7 lifters
Gen 4 rods
ARP PRO Series Connecting Rod Bolts 234-6301 Rollmaster ls1 double-roller adjustable timing set
MAHLE 930218980 5.3L Gen 4 LS Forged Pistons, Flat Top (yes they have valve reliefs)
Ls1 Denso fuel injectors
COMP Cams 54-602-11 Big *****' Thumpr 235/249 Hydraulic Roller Cam
COMP Cams 26918CS-KIT LS Engine Beehive Valve Spring Kit
Melling 10295 High-Pressure oil Pump
LS9 7-layer gasket
ARP PRO Series Cylinder Head Studs 234-4317
4" cold air intake pipe and a massive filter
1 7/8" long tube headers going into a 3" dual exhaust
t56 clutch ( Centerforce DF395010 Dual Friction Clutch )
The ecu that I'll be running is from a 2003 LS1 Corvette (ill need to reflash to some stock 5.3, and then go from there (if anyone does have or is willing to help me out with a basic start-up tune, I'd really appreciate it))
I believe this is it. This engine is being swapped into my 1998 BMW e36 M3
I appreciate everyone's time reading this post.
Thank You!
Current status of the build
Last edited by Laki; 09-03-2023 at 09:51 PM.
Reason: .
You will need someone who really knows what they are doing to tune the idle on that. It will probably NOT idle in closed loop with that much overlap. In a 5.3 you are trading off lots of low end with a cam that big, so I hope you are planning on gearing the rear end pretty low. Even then, plan on spending a lot of time fine tuning your low rpm to avoid unnecessary bucking. If you were after a ridiculously lumpy idle and screaming high rpm power you should be good. If you plan on putting around the neighborhood you are screwed.
First off, I may sound harsh or mean but I don't intend to. In fact, I really like your swap, however, that is a Very large intake, Very large Camshaft, and very large headers for a 5.3 l when I say very large I mean the geometry is just not complimentary for the displacement engine you have. An engine is an air pump and those parts are going to really hurt the engines ability to create air velocity at lower speeds significantly reducing torque and throttle response significantly If you were set on using those parts, the cheapest thing on your build list at this point to replace would be the short block. Going from stock to those parts on a larger engine would still even show a significant hit to the bottom end performance, I would suggest a 5.7 a 6.0 or a 6.2 replace the five three short block with that and everything else you have will work and run great with a Thorough street tune. The 862 heads will maximize low speed air velocity on the larger engine. Helping give you a wider power band with that big honking camshaft, Otherwise, you're going to have a incredibly finicky underperforming example of a Gen 3 small block Chevy that won't idle, won't drive right with the massive throttle body and will only make power above 5K RPM,
That cam spec alone would be a pain in the *** on a large engine let alone a smaller one. Not trying to be rough Just trying to help. Yes, all the parts you have will physically bolt together but they just won't work well at all on the smaller displacement engine.
If you want a driveable combo, get a Summit Ghost Cam or if you want bigger get a Cam Motion Titan 4. You can have your tuner play with spark at idle to get some chop.
First off, I may sound harsh or mean but I don't intend to. In fact, I really like your swap, however, that is a Very large intake, Very large Camshaft, and very large headers for a 5.3 l when I say very large I mean the geometry is just not complimentary for the displacement engine you have. An engine is an air pump and those parts are going to really hurt the engines ability to create air velocity at lower speeds significantly reducing torque and throttle response significantly If you were set on using those parts, the cheapest thing on your build list at this point to replace would be the short block. Going from stock to those parts on a larger engine would still even show a significant hit to the bottom end performance, I would suggest a 5.7 a 6.0 or a 6.2 replace the five three short block with that and everything else you have will work and run great with a Thorough street tune. The 862 heads will maximize low speed air velocity on the larger engine. Helping give you a wider power band with that big honking camshaft, Otherwise, you're going to have a incredibly finicky underperforming example of a Gen 3 small block Chevy that won't idle, won't drive right with the massive throttle body and will only make power above 5K RPM,
That cam spec alone would be a pain in the *** on a large engine let alone a smaller one. Not trying to be rough Just trying to help. Yes, all the parts you have will physically bolt together but they just won't work well at all on the smaller displacement engine.
Really appreciate Your honest response. I do agree with You, i should have gone with a 6.0, and I probably will once I finish this swap. The thing is, I really need to see whether I have correctly managed to swap this into my BMW. Once I'm sure that this thing works, all of the electronics etc work. I will definitely be looking for a 6.0 and rebuilding it, and probably swap the more expensive bits over, and sell the 5.3 with the forged pistons and etc. Nevertheless Thank You for taking the time and trying to help me out.
On the bright side, since you have a t56, you don't have to worry about killing a 4l60 with the rpm this motor will need to shift at. And even though the large throttle will be "twitchy" at low rpm and torque will be low, it can be tuned to be drivable. It will just be no fun until the tach climbs a ways up the scale.
Would this cam be good for my application? Would it free up the most hp ? I also saw the summit stage 4 cam, but i can get a discount on the 469, just wondering if it would fit fine with my p-v clearance. My max spring lift is .625 and the 469 is at .617 Is that too risky ? Would 54-659-11 be better ?
Those are still enormous cams that will be miserable to drive anywhere but a racetrack in a 5.3. You do realize you are looking at cams with 40 or 50 degrees more duration at .050" than stock, don't you?
Those are still enormous cams that will be miserable to drive anywhere but a racetrack in a 5.3. You do realize you are looking at cams with 40 or 50 degrees more duration at .050" than stock, don't you?
Thank You for replying to my post. I do realize that the cams I'm looking at are extremely big. However, due to my recent financial struggles after paying for college, I'm only able to look at cams that I have a massive discount on from a friend of mine. The cams that I can choose right now are 54-469-11, 54-459-11, and 54-454-11. I'd personally pick the 454 because I can get it cheapest for 120$ and I guess it should be fine with my setup, it would be definitely better than the massive cam I have atm. I wish to have better options, but that's all he has for a low price, and I really don't have the money at this moment to spend +$400 on a cam.
Thank You for contributing, and trying to help me out.
For the COMP Cams 54-454-11 , will I need to upgrade my springs too ? Richard Holdener used this exact cam, with these springs, and I have the exact ones too: " https://www.compcams.com/beehivetm-valve-springs-top-1-075-o-d-650-i-d-bottom-1-310-o-d-885-i-d-1.html" these are to be .625 max lift, but after calculating the coil bind, it gave me .610. Therefore now idk...
I would leave the cam that is already in it. The difference in drivability and tuning requirements will be splitting hairs on any of the ones you mentioned. There WILL be differences, but not enough to waste time on when you already know the combination is not optimal anyway.
really appreciate your honest response. I do agree with you, i should have gone with a 6.0, and i probably will once i finish this swap. The thing is, i really need to see whether i have correctly managed to swap this into my bmw. Once i'm sure that this thing works, all of the electronics etc work. I will definitely be looking for a 6.0 and rebuilding it, and probably swap the more expensive bits over, and sell the 5.3 with the forged pistons and etc. Nevertheless thank you for taking the time and trying to help me out.
Why do the same job twice !? That big magical exciting Happy fun Camshaft that helps the engine misfire and make exciting banging sounds in the parking lot and scares the girls away is going to make sorting out the rest of the swap and absolute nightmare.
The best way to sort out a newly swap vehicle is to leave the stock camshaft in it while you smooth out all the other wiggles and bumps, The camshaft adds a whole lot of issues that you don't want just yet. If you put that cam in an LS powered vehicle that was already set up and made with an LS from the factory, it would still run like absolute s*** craps and take a ton of tuning and a bunch of other supporting parts to work properly. Why don't you understand this.
The parts you have matched together are not a match at all we are all telling you already that you have not correctly managed the swap but go ahead prove us wrong. Yes we know that the parts will all bolt together and you are ready to reinvent the wheel but it's just not going to work the way you want it to.
I'm autocrosser and so I see swaps like yours all the time and guess what MOST of the time they are slower than if they would have just left the stock engine in the damn thing! You go ahead an make your car " talk the talk" That's easy enough. Anybody can make their engine misfire
I'm guessing it has no cam whatsoever in it right now?
Decide what you want out of the car. You haven't really told us what it's going to be used for. If you want a car that drives with spirit, the BMT is NOT the one for you. If you want to impress teenagers with "lope" but don't care even if it can pull itself up onto a trailer without a winch, then yeah, the BMT, or some similar thing, maybe that gigantic Comp, might be the ticket.
I'm seeing a basically stock 07-up 5.3 with a big intake and headers on it. Stock otherwise. Already a recipe for a dog of a motor with no "*****". It won't make any more power than the stock intake would have until it reaches some VERY high RPM, and will make LESS at all RPMs lower than that. Pretty paint job in lots of flashy colors won't add a damn bit of power at any RPM.
You already have too much compression for very much boost. Not a good combo for that. Good for N/A, not so much for boost. You don't just "throw" or "slap" boost onto just ANY motor, and get guaranteed world-beating power.
The Comp 454 grind is 227/243° @ .050". Pretty big: kinda on the biggish side in a 5.7 even. Too much cam for a 5.3 with stock heads. Too much duration split toward the exh side also, which the small motor with small intake valves doesn't need. Not a good choice for driving except at the strip.
I'd suggest some one of the dozens available from Summit, TSP, Vinci, BTR, etc. etc. that are more in the 216/220° @ .050" sort of range. Preferably advanced a few degrees over stock (either in the grind or by installation), and on a narrower LSA, like 110 - 112°. It'll give you a little bit of "rattle" in the 5.3 but won't kill the bottom end and the leave like those YYYYYYUUUUUUUUJJJJJJE other ones will.
I just got a different cam in, it's Comp Cams 54-444-11 I believe it should be relatively decent compared to the one I had, Given the tight budget. Eventually, ill put a turbo in. But that will be when I finish welding my turbo manifolds, and my financial situation stabilizes.
I appreciate everyone's time and effort in trying to help me out. I guess this thread can come to an end since the cam is to be swapped.
09-03-2023, 09:15 PM
Gen 3 5.3ls Big ***** Thumpr Cam will it run ??? 
