Has Anyone Successfully Turboed a Truck and Kept the Stock Cats or Any Cats??
08-31-2021, 12:36 PM
#41
I'll stop you right there
Centri's are actually preferred for road course because the power delivery is linear. Its an NA power band, just more of it. You don't need to worry about a bunch of lower RPM torque trying to overwhelm the drive tires. In the case of Corvette's, the rear. Which losing the rear at the bottom of second gear and going bass ackwards into a wall because 500ft/lbs of torque caught you off guard is not my idea of fun lol
08-31-2021, 12:52 PM
#42
I think it depends on how hard you want to lean on it. Prochargers depreciate the fastest/ lowest, therefore used ones are often under 2k, pre-covid. Gen 3 roots/tvs/whipples aren't really manufactured anymore so its a supply and demand thing there. Used ones are more expensive because its hard or impossible to find new ones, so supply and demand
As for the cost, a turbo build is the same price. The "stage 1" kits might seem cheaper but after a tune/injectors/AC mods its gonna be similar to a NIB blower kit that is all inclusive with a canned tune
For the speed; I don't see many turbo SUVs deeper than the 11s either, so you're gonna have to be more specific. Getting 6000lbs down the 1/4 is A) hard, physics fights everything about it B) Drag racing is dumb
That said, the fastest SUV I know of was an LSA blown 427 GMT900 Escalade and if I recall he was in the high 9s or low 10s. Not a stock motor at all, he used an LSX block. So to expect to be faster than 11s on SBE whether turbo or blower, I think is a far cry. The limit with blowers and HP is the blower RPM, eventually you can't spin it faster to move more air, it just becomes heated air or suffers cavitation. From there you go to a bigger blower and so on so forth. Turbo's aren't immune to this either, but to make matters worse a turbo that will "carry" high RPM air will suffer down low. There is no free lunch and you have to pick which compromise you're willing to make
But now you're having scope creep. First it was "I want to turbo and keep cats" ok, possible with some work and understanding nothing is going to be optimized for dyno queen numbers. Now its "I want to be deeper than 11s, make more than 5-600 and not modify my AC"
So whats your real goal? If you want to challenge Vettes and Mustangs and sports bikes; you picked the wrong ride
I mean realistically, 5-600 is all you're going to be able to make and keep things like the cats, trans, rear end and bottom end together anyway. Blower is the easiest way to get there. Offers the most off idle torque and will be the most fun to drive around the city
As for the cost, a turbo build is the same price. The "stage 1" kits might seem cheaper but after a tune/injectors/AC mods its gonna be similar to a NIB blower kit that is all inclusive with a canned tune
For the speed; I don't see many turbo SUVs deeper than the 11s either, so you're gonna have to be more specific. Getting 6000lbs down the 1/4 is A) hard, physics fights everything about it B) Drag racing is dumb
That said, the fastest SUV I know of was an LSA blown 427 GMT900 Escalade and if I recall he was in the high 9s or low 10s. Not a stock motor at all, he used an LSX block. So to expect to be faster than 11s on SBE whether turbo or blower, I think is a far cry. The limit with blowers and HP is the blower RPM, eventually you can't spin it faster to move more air, it just becomes heated air or suffers cavitation. From there you go to a bigger blower and so on so forth. Turbo's aren't immune to this either, but to make matters worse a turbo that will "carry" high RPM air will suffer down low. There is no free lunch and you have to pick which compromise you're willing to makeBut now you're having scope creep. First it was "I want to turbo and keep cats" ok, possible with some work and understanding nothing is going to be optimized for dyno queen numbers. Now its "I want to be deeper than 11s, make more than 5-600 and not modify my AC"
So whats your real goal? If you want to challenge Vettes and Mustangs and sports bikes; you picked the wrong ride
I mean realistically, 5-600 is all you're going to be able to make and keep things like the cats, trans, rear end and bottom end together anyway. Blower is the easiest way to get there. Offers the most off idle torque and will be the most fun to drive around the city
I would be happy to have 5-600. I was just using the 11s and supercharger thing as an example I think its more like 12s probably. I think most peoples trucks are way overweight and have 1000s of pounds of tools and stuff in them haha. I keep absolutely nothing in mine and its a gmt900 Denali and it weighed 5275 without me in it. My 6th gen camaro weights 3870 and it is barely any better than stock, but its all NA with drag radials. I tried gears, converter, full headers/exhaust as well and now I am trying to sell all that stuff. I just figured I could do it cheaper and easier with a more common GEN III/IV platform. Too me 25% more weight is not that much. I see what you are saying though, I just think people keep a mobile maintainace shop in their trucks haha
08-31-2021, 01:07 PM
#43
I'll stop you right there
Centri's are actually preferred for road course because the power delivery is linear. Its an NA power band, just more of it. You don't need to worry about a bunch of lower RPM torque trying to overwhelm the drive tires. In the case of Corvette's, the rear. Which losing the rear at the bottom of second gear and going bass ackwards into a wall because 500ft/lbs of torque caught you off guard is not my idea of fun lol
Centri's are actually preferred for road course because the power delivery is linear. Its an NA power band, just more of it. You don't need to worry about a bunch of lower RPM torque trying to overwhelm the drive tires. In the case of Corvette's, the rear. Which losing the rear at the bottom of second gear and going bass ackwards into a wall because 500ft/lbs of torque caught you off guard is not my idea of fun lol
having road coursed my TVS corvette plenty of times over the last decade, i can attest that your comments are a little less than accurate.just hop over on corvetteforum & check out what type of racing the vast majority of centri owners do (hint: it's overwhelmingly in a straight line). since a centrifugal is essentially a turbo with built-in mechanical lag, it launches much easier & then gets meaner (and squirrelier) the longer your foot's in it. at least that was my experience with the two different centri LS cars i've driven in the past. as for the power 'curve': it's almost a slope of 1 because the more RPMs you give it, the more air it moves & torque it makes (tempered by the wastegate, of course [e.g., using a big centri with a light spring and/or a restrictor plate will be much flatter but also severely limit its upper potential]).
to be fair, most road coursers are N/A, but the PD blowers are more predictable & consistent for throttle roll-in & lateral transitions because the torque's fairly consistent across the RPMs & boost is controlled by your foot. the folks comfortable with various throttle positions between off & floor enjoy the feel & not having to wind the engine out or wait on spool. oh, by the way... do any OEMs use centrifugals when building forced induction performance variants - particularly for road circuits? they use PD or turbo.
turbo is kind of the best of both worlds... but not. you can build something that spools quick enough to provide that instant torque like a PD (but running out of steam up top in the same manner) or pulls like a freight train until you lift but taking more RPM to make that happen. either way, you'll have torque earlier than a centri.
...sorry for the side bar; more about catalytic converters!
08-31-2021, 01:54 PM
#46
Agree to disagree. If your experience on a track differs, that's fine. My C5 that will pretty much only live on a track, should it ever run on all 8; will never see a PD. It doesn't have the electronics or the R&D to manage that much rear wheel torque (speaking to your point about OEs. Every car in the last decade that is OE boosted with a TVS has wayyyyy more TC than our C5s)
Also to that point, I'd rather have the less heat a turbo or centri provides to the compressed air during a 20min session. Also, the less weight of either system. But, now we are getting into the weeds and comparing a track car to a street driven 6000lb truck
So, moving on
For the SUV weight comment; some of us have weight we can't remove. My Tahoe weighs 5920 full of fuel, and its not a drag racer because drag racing 6000lbs is dumb. But to put her on a diet, I have to remove bumpers, 9.5 rear end, 5 E range tires, ~200lbs of sound insulation, my extra fuel tank and my (very) small stereo. So to clarify, with no recovery gear in my truck, and no tools; I roll around at almost 6k lbs when full of fuel; without me in the truck
+25% weight is huge. The ricer math says every 1000lbs gained or lost is equal to 100hp. Weight matters. And having the hp to move the wight is only part of it. You have to turn it and stop it too. I often laugh when I see huge turbo builds with 20k under the hood and stock brakes. So, we can spend 20k on going but cant spend 2k on stopping it?
To each their own. Pick you poison, pick your budget, pick whether you want turbo lag, or soft hitting boost that builds with RPM or an instant surge or torque and hp that bleeds off in the high RPMs
You can have some of your cake and eat it, you just have to be willing to work for it with fabrication and tuning and making a compromise
Also to that point, I'd rather have the less heat a turbo or centri provides to the compressed air during a 20min session. Also, the less weight of either system. But, now we are getting into the weeds and comparing a track car to a street driven 6000lb truck
So, moving on
For the SUV weight comment; some of us have weight we can't remove. My Tahoe weighs 5920 full of fuel, and its not a drag racer because drag racing 6000lbs is dumb. But to put her on a diet, I have to remove bumpers, 9.5 rear end, 5 E range tires, ~200lbs of sound insulation, my extra fuel tank and my (very) small stereo. So to clarify, with no recovery gear in my truck, and no tools; I roll around at almost 6k lbs when full of fuel; without me in the truck
+25% weight is huge. The ricer math says every 1000lbs gained or lost is equal to 100hp. Weight matters. And having the hp to move the wight is only part of it. You have to turn it and stop it too. I often laugh when I see huge turbo builds with 20k under the hood and stock brakes. So, we can spend 20k on going but cant spend 2k on stopping it?
To each their own. Pick you poison, pick your budget, pick whether you want turbo lag, or soft hitting boost that builds with RPM or an instant surge or torque and hp that bleeds off in the high RPMs
You can have some of your cake and eat it, you just have to be willing to work for it with fabrication and tuning and making a compromise
08-31-2021, 01:58 PM
#47
Rule of thumb, without spelling out all the nuances is: the bigger the motor the better the exhaust. For the intents of this thread Gen3 4.8/5.3/6.0 share manifolds (but not exhaust systems) and gen4 4.8/5.3 share manifolds. Gen4 6.0/6.2 got bigger exhaust; I am unsure if that started at the manifolds or after the cats
08-31-2021, 01:58 PM
#48
Also when I change the oil pan gasket out (because I think its leaking) I am going to drill and tap the oil pan anyway. Even if I don't do anything with the truck and leave it stock its not going to matter if I have it tapped as long as I can seal it back. Not sure if most people use thread sealant or how they normally do it. I believe from looking most people use NPT barb fittings, I am just not sure why you would use NPT thread on a thin oil pan tap. I will have to pull the pan off to tap it since I have AWD and the differential is in the way. I barb fitting seems kind of cheap to use but I guess its ok for a drain, but I'm not sure what other "higher quality" thing you would put in there.