5.3 terrible performance
Thread Starter
Teching In
Joined: Jan 2024
Posts: 48
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I just got my set of 4.10s to install. Ill be adding the boost and terminator x when i get a free couple days.
i guess i was just expecting too much out of it NA. I always planned to boost but wanted to get through initial start up and check for bugs. I had no idea it would be so bad... i originally had a 3200-3500 converter which obviously felt better bc it took off in power band but wasn't the greatest to drive around. Doable, not ideal. Im sure someone will now say they drive through rush hr traffic with a 10000 stall converter lolol.
Thanks for input. Ive had alot of good input here.
i guess i was just expecting too much out of it NA. I always planned to boost but wanted to get through initial start up and check for bugs. I had no idea it would be so bad... i originally had a 3200-3500 converter which obviously felt better bc it took off in power band but wasn't the greatest to drive around. Doable, not ideal. Im sure someone will now say they drive through rush hr traffic with a 10000 stall converter lolol.
Thanks for input. Ive had alot of good input here.
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Joined: Jul 2022
Posts: 1,019
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From: Alaska
Going at things backwards. You likely don’t need or want 4.10’s once you go turbo. Depending on what you use the truck for anyway. It will have the potential to make more than enough power to pull the current gear. Get the turbo on it first. Then sort your bugs. Your compression ratio is fine.
Not the first area I’d spend money on anyway. Get that converter out of there, it will be terrible. A change in converter will make much more of difference than a gear swap. If you go with Circle D shelf stuff beware. They are always a lot tighter than advertised IMO. Id ask for a 4500rpm stall if you wanted 3400ish on a mild 5.3 like you have.
Aside from all that, it sounds like you don’t have the setup tuned and don’t have the equipment to monitor it? Get a WB02 on there and stop guessing and throwing parts at it.
Not the first area I’d spend money on anyway. Get that converter out of there, it will be terrible. A change in converter will make much more of difference than a gear swap. If you go with Circle D shelf stuff beware. They are always a lot tighter than advertised IMO. Id ask for a 4500rpm stall if you wanted 3400ish on a mild 5.3 like you have.
Aside from all that, it sounds like you don’t have the setup tuned and don’t have the equipment to monitor it? Get a WB02 on there and stop guessing and throwing parts at it.
Thread Starter
Teching In
Joined: Jan 2024
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Tie into downpipe and run cutout through fender. When closed exh going to be weird? Added 411s and 3100 stall converter. Now its turbo time.
cutout through fender or big problems with exh flow when capped?
cutout through fender or big problems with exh flow when capped?
Thread Starter
Teching In
Joined: Jan 2024
Posts: 48
Likes: 7
Cutout from turbo downpipe I'm just about to install my Turbo I have a prefab downpipe and my question is would it be ridiculous to weld a y on to that down pipe and have a dump come out the front fender with a cutout cover. When the cutout cover is on with that cause all sorts of problems with exhaust pressures or should I just let it go out the bottom and abandon the idea of the cutout coming out the side fender any ideas?
Joined: Apr 2006
Posts: 3,865
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From: Grand Rapids, Michigan
Everything I've read says steep gears with a turbo are bad news. Unless you're running 31" tires, then 4.10's won't be so bad. Turbos work best when an engine is loaded. Stabbing high ( numerical ) gears into your axle will instantly diminish the load your engine sees, which allows it to rev faster. But the turbo won't spool as quickly because the engine isn't blasting as much heat into the exhaust. If your engine revs faster than your turbo can spool, the turbine can appear to the engine as a restriction akin to a potato in your tailpipe. Think of the turbo and engine as being in a race. You'll be faster as long as the turbo is winning.
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3.73’s and a .68 got old for me cruising at the 70-80 mph range.
Last edited by Y2K_Frenzy; Mar 14, 2024 at 05:15 PM.
Joined: Apr 2006
Posts: 3,865
Likes: 1,122
From: Grand Rapids, Michigan
Yes, even with those ratios. I've seen 8 second cars with a TH400 that run a 3.08 rear gear. You're going to rev through first pretty fast with 4.10s and a 28" tire. You should have only been turning around 2500 with 3.73's and .68 overdrive, though. That's not that bad.
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Yes, even with those ratios. I've seen 8 second cars with a TH400 that run a 3.08 rear gear. You're going to rev through first pretty fast with 4.10s and a 28" tire. You should have only been turning around 2500 with 3.73's and .68 overdrive, though. That's not that bad.
Thread Starter
Teching In
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3.42s swapped for 4.11s. Getting closer to turbo installation. Holley terminator x
holley 100lb injectors
Walbro 450
5.3 gen 3
Engine fully rebuilt and all forged internals all arp fastners
Btr cam 224 227 605 lift
dual springs
Ls7 rockers
Tbss intake
92mm TB
243 heads
Question is, do i install my cheapo gt45 ebay or slightly less cheapo on3 76/75.
4l80 segment swap.
O5 sierra
31 inch tires
vsr BOV and 44mm wastegate
3" mishimoto air to air intercooler
Im a little afraid of the gt45 destroying my engine ive worked so hard on.
gr45ive read the on3 may starve engine though.
hoping to run about 12 tov15 lbs boost
Any advice on which turbo to run?
holley 100lb injectors
Walbro 450
5.3 gen 3
Engine fully rebuilt and all forged internals all arp fastners
Btr cam 224 227 605 lift
dual springs
Ls7 rockers
Tbss intake
92mm TB
243 heads
Question is, do i install my cheapo gt45 ebay or slightly less cheapo on3 76/75.
4l80 segment swap.
O5 sierra
31 inch tires
vsr BOV and 44mm wastegate
3" mishimoto air to air intercooler
Im a little afraid of the gt45 destroying my engine ive worked so hard on.
gr45ive read the on3 may starve engine though.
hoping to run about 12 tov15 lbs boost
Any advice on which turbo to run?
Joined: Apr 2006
Posts: 3,865
Likes: 1,122
From: Grand Rapids, Michigan
Your engine combo is nearly identical to what I'm building, and I have a VS Racing 78/75 Gen 2.5. I'm not going for max effort power-wise though. Size your turbo for the maximum power you want to make. I'm looking for 750-850 RWHP, which this turbo is capable of making easily. I have a stick shift too, so I designed my combo to compliment that. Boost level isn't as important as ultimate power goals.
TECH Fanatic
Joined: Jan 2022
Posts: 1,362
Likes: 256
Holley terminator x
holley 100lb injectors
Walbro 450
5.3 gen 3
Engine fully rebuilt and all forged internals all arp fastners
Btr cam 224 227 605 lift
dual springs
Ls7 rockers
Tbss intake
92mm TB
243 heads
Question is, do i install my cheapo gt45 ebay or slightly less cheapo on3 76/75.
4l80 segment swap.
O5 sierra
31 inch tires
vsr BOV and 44mm wastegate
3" mishimoto air to air intercooler
Im a little afraid of the gt45 destroying my engine ive worked so hard on.
gr45ive read the on3 may starve engine though.
hoping to run about 12 tov15 lbs boost
Any advice on which turbo to run?
holley 100lb injectors
Walbro 450
5.3 gen 3
Engine fully rebuilt and all forged internals all arp fastners
Btr cam 224 227 605 lift
dual springs
Ls7 rockers
Tbss intake
92mm TB
243 heads
Question is, do i install my cheapo gt45 ebay or slightly less cheapo on3 76/75.
4l80 segment swap.
O5 sierra
31 inch tires
vsr BOV and 44mm wastegate
3" mishimoto air to air intercooler
Im a little afraid of the gt45 destroying my engine ive worked so hard on.
gr45ive read the on3 may starve engine though.
hoping to run about 12 tov15 lbs boost
Any advice on which turbo to run?
Thread Starter
Teching In
Joined: Jan 2024
Posts: 48
Likes: 7
Thread Starter
Teching In
Joined: Jan 2024
Posts: 48
Likes: 7
I'd really like to have someone's input on installing the on3 7675 or the cheap eBay turbo GT 45 clone I know they're both cheap garbage but I can't afford a Garrett at the moment which would you install? I know the on3 will spool faster but I'm afraid it's going to run out of juice around 5K
TECH Fanatic
Joined: Jan 2022
Posts: 1,362
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I'd really like to have someone's input on installing the on3 7675 or the cheap eBay turbo GT 45 clone I know they're both cheap garbage but I can't afford a Garrett at the moment which would you install? I know the on3 will spool faster but I'm afraid it's going to run out of juice around 5K
Joined: Apr 2006
Posts: 3,865
Likes: 1,122
From: Grand Rapids, Michigan
One thing to remember with a turbo is, as long as you keep the same configuration ( T4 vs. T6, same size downpipe and outlet configs ), you can upgrade down the road to a better performing turbo and only have to change the turbo itself, and touch up the tune.
Whats the target HP? Thats how you spec the turbo and the cam. Stay away from the GT45, the price is nice but the smaller frame turbos will destroy them on spool, efficiency and size. Those Gt45s are huge and heavy with bad exhaust design and tiny impellers. They work but on a 5.3 need RPM to spool where a 78/75 wouldn't need a whole lot plus be able to package easier. How much HP you want? how much boost? Are you limited in space?
Designing to a t6 gives you more options for overall growth but your going bigger turbo right off the batt. Like stated designing the system off the line so you can swap turbos for more power will make your life easier. If you planning 800hp then you could prob get away with a larger T4 but your in t6 territory if your planning on all the boosts. WHich you build suggests which is 100lb injectors (assuming pump gas) and forged internals.
Designing to a t6 gives you more options for overall growth but your going bigger turbo right off the batt. Like stated designing the system off the line so you can swap turbos for more power will make your life easier. If you planning 800hp then you could prob get away with a larger T4 but your in t6 territory if your planning on all the boosts. WHich you build suggests which is 100lb injectors (assuming pump gas) and forged internals.