5.3 cam only - need advice
09-09-2016, 11:19 PM
#1
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5.3 cam only - need advice I have a 1973 Corvette I just swapped an lsx into. Long story short, it made 350/312 at the wheels, yet all the power seems too far in the power band so it's a dog off the line... please let me know what I can do within reason to help...cant even burnout.. Here are the specs.
Stock bottom 5.3
243 heads milled .017 to keep compression (in theory) at 9.5:1
Texas speed 228r cam
Ls6 intake
Beehive springs
1 3/4 long tube headers
2.5" full exhaust
Th400
3.08s in the back.
Stock bottom 5.3
243 heads milled .017 to keep compression (in theory) at 9.5:1
Texas speed 228r cam
Ls6 intake
Beehive springs
1 3/4 long tube headers
2.5" full exhaust
Th400
3.08s in the back.
09-09-2016, 11:43 PM
#4
TECH Veteran
Anytime you run over a 220 duration cam in a 5.3 you go start to lose power down low and pull hard up top. You never mentioned what stall you running.... I would go 3500 minuim and more rear gear ratio will help you pull out the hole as well.
09-10-2016, 12:38 AM
#6
TECH Veteran
Ditch the 3.08 gears and that stall.
I would try a 3.42 gear with a 3500 stall... I think you will be happy.
I would try a 3.42 gear with a 3500 stall... I think you will be happy.
09-10-2016, 01:00 AM
#7
the lack of overdrive suggests this is a race-car only (trailer car) so I feel that 3.73 or 4.11 are more appropriate gear ratios.
If you keep the 3.08 I would drop the cam (use a 218/224 ish) and add a turbocharger (bring power to around 450rwhp) but its still lacking overdrive so not a street car, no economy.
The reason it feels slow is the gearing and lack of boost, combined with the slush of a 3-speed no lockup against a converter and a bunch of weight. Alternatively you could shave 1000lbs off but that is probably harder than adding a turbo.
If you keep the 3.08 I would drop the cam (use a 218/224 ish) and add a turbocharger (bring power to around 450rwhp) but its still lacking overdrive so not a street car, no economy.
The reason it feels slow is the gearing and lack of boost, combined with the slush of a 3-speed no lockup against a converter and a bunch of weight. Alternatively you could shave 1000lbs off but that is probably harder than adding a turbo.
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09-10-2016, 03:27 AM
#10
I guess you missed this part in his first post "please let me know what I can do within reason to help"
As others have already pointed out and as you felt in the seat of the pants, Your cam isn't making power down low so to compensate you need to get the motor up in the powerband sooner, More stall will fix that and gears will help keep the momentum going.
09-10-2016, 05:40 AM
#11
the lack of overdrive suggests this is a race-car only (trailer car) so I feel that 3.73 or 4.11 are more appropriate gear ratios.
If you keep the 3.08 I would drop the cam (use a 218/224 ish) and add a turbocharger (bring power to around 450rwhp) but its still lacking overdrive so not a street car, no economy.
The reason it feels slow is the gearing and lack of boost, combined with the slush of a 3-speed no lockup against a converter and a bunch of weight. Alternatively you could shave 1000lbs off but that is probably harder than adding a turbo.
If you keep the 3.08 I would drop the cam (use a 218/224 ish) and add a turbocharger (bring power to around 450rwhp) but its still lacking overdrive so not a street car, no economy.
The reason it feels slow is the gearing and lack of boost, combined with the slush of a 3-speed no lockup against a converter and a bunch of weight. Alternatively you could shave 1000lbs off but that is probably harder than adding a turbo.
Your logic is backwards and makes no sense. Your theory of making down low off idle power is adding turbos that run off exhaust gas which is greater at higher rpm instead of adding a mechanically advantage that gives him more off idle
Just add a set of gears first off and see how you like it then look into a better stall.
09-10-2016, 07:44 AM
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Scott5, you're correct. She is my weekend/nice day car. The TH400 is what came in the car, and I have been looking into a 4l80e swap to see if it'll fit.
I just swapped to the lsx from a small block that was making roughly the same power. Roller cam, s/r torquer heads, rpm air gap etc. Not really any faster (I dont think), but now get 15mpg or so vs 8.
Would you guys suggest milling the heads any more, to being up compression? That's only a couple hundred bucks and some time.
I will also look into some 3.73s, but then an overdrive gear or two would be nice and help with a little economy when I'm not deep in the pedal.
I just swapped to the lsx from a small block that was making roughly the same power. Roller cam, s/r torquer heads, rpm air gap etc. Not really any faster (I dont think), but now get 15mpg or so vs 8.
Would you guys suggest milling the heads any more, to being up compression? That's only a couple hundred bucks and some time.
I will also look into some 3.73s, but then an overdrive gear or two would be nice and help with a little economy when I'm not deep in the pedal.
09-10-2016, 07:48 AM
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Please let me know the closest turbo kit dollar store to Kansas City! My friend is wrapping his tt setup on a 6.0, but he has spent waaay more $ than I have, and he is a full on 'street car' with a parachute and 4 digit HP.
