Turbo 5.3 with big cam.
06-23-2014, 10:12 AM
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Turbo 5.3 with big cam. I am building a fox body with a 5.3 turbo. It used to be a carbed setup, but now i am switching to efi with stock pcm. I currently have a 5.3 with a ms3 on 112 lsa. I know the came is big and not ideal with a turbo. My question is will it still run good on 9-10 psi or will it lose alot of boost out the exhaust. My turbo it a 76mm on3. Thanks, Jared
06-23-2014, 12:08 PM
#4
lets see if one of the cam guys reply . i know that long exaust lobe will not work well with much backpressure like your on3 turbo will have. it whould be better with a large exaust wheel like a s475 has. but they will have some first hand experiance that will help .
it also depends on your convertor and trans. to get it spooled. if you cant get it out of the hole it wont et very good. you can try pming stock48 he is a good guy and he could give you a better idea. he might post as well. .
it also depends on your convertor and trans. to get it spooled. if you cant get it out of the hole it wont et very good. you can try pming stock48 he is a good guy and he could give you a better idea. he might post as well. .
06-23-2014, 12:11 PM
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How much boost you planning on?
My guess would be 50rwhp midrange, 20rwhp up top and 500rpm later spooling. But it'll sound sick though!
You have any idle clips? i bet that thing thumps.
My guess would be 50rwhp midrange, 20rwhp up top and 500rpm later spooling. But it'll sound sick though!
You have any idle clips? i bet that thing thumps.
06-23-2014, 01:15 PM
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I dont know on amount of boost. I am going to try and keep it under 15psi. I plan on just running 8-10 psi to start with. I would be more then happy if it made 525-550 horse at the wheels on 9-10 psi. I have a th400 with a 3600 stall and a 3.73 reag gear.
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06-23-2014, 02:33 PM
#9
When it comes to turbo cams... if it runs good n/a it will run good with a turbo. It will act just like it did n/a, torqueless till 5k then pull like a train. Only problem im seeing is your cam starts to pull at the same time the exhaust starts to choke on the turbo. Bigger exhaust side turbo or smaller cam would work better, but I say try it if it's in there already it might surprise you...
06-23-2014, 02:55 PM
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Ya i was actually surprised na the little 5.3 with the ms3 cam actually had power at around 4k. I just dont want the boost to bleed out and not make power. Ill be happy if it matches the power of like say a ls6 cam.
06-23-2014, 03:23 PM
#11
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When it comes to turbo cams... if it runs good n/a it will run good with a turbo. It will act just like it did n/a, torqueless till 5k then pull like a train. Only problem im seeing is your cam starts to pull at the same time the exhaust starts to choke on the turbo. Bigger exhaust side turbo or smaller cam would work better, but I say try it if it's in there already it might surprise you...
06-23-2014, 04:25 PM
#12
You ever seen a turbo cam run faster then a n/a cam? Some people have this wild idea you will push all boost out the exhaust when you have more exhaust pressure then boost pressure, on the sc engine you have to be careful but turbo engines will take almost any cam. Look at speed inc. Turbo cams then compare them to what texas speed puts in the same engine n/a.
06-23-2014, 05:23 PM
#13
What is your definition of "run good"? My car is faster with the stock cam than it was with a bigger turbo cam. It depends on your setup. I've only foot braked my car and the extra torque down low really helped get the car out of the hole. The valve train is whisper quiet now and I get better fuel mileage. I did 504rwhp/617lbft at 8.6lbs through a th400 so your goal seems to be inline. I went from 12" of vacuum to 21". I would never do the big cam thing again if it were me but you have it so try it. If you don't like it a cam swap is doesn't take very long.
06-23-2014, 05:51 PM
#14
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What is your definition of "run good"? My car is faster with the stock cam than it was with a bigger turbo cam. It depends on your setup. I've only foot braked my car and the extra torque down low really helped get the car out of the hole. The valve train is whisper quiet now and I get better fuel mileage. I did 504rwhp/617lbft at 8.6lbs through a th400 so your goal seems to be inline. I went from 12" of vacuum to 21". I would never do the big cam thing again if it were me but you have it so try it. If you don't like it a cam swap is doesn't take very long.
06-23-2014, 07:28 PM
#18
When it comes to turbo cams... if it runs good n/a it will run good with a turbo. It will act just like it did n/a, torqueless till 5k then pull like a train. Only problem im seeing is your cam starts to pull at the same time the exhaust starts to choke on the turbo. Bigger exhaust side turbo or smaller cam would work better, but I say try it if it's in there already it might surprise you...
the key is selecting a turbo to compliment the rpm range the cam/engine dictates, and setting up the drive train to take advantage of the rpm range that your cam/engine/turbo combo give you.
I personally think your combo will be fine, BUT the turbo will choke before the engine is done, and when you step up to a good flowing turbo, you will need a very good converter.
what are the exact specs of the turbo?
Must be more... 