Turbo 5.3 Low dyno numbers.
Thread Starter
Teching In
Joined: Oct 2018
Posts: 11
Likes: 1
Turbo 5.3 Low dyno numbers. Greetings,
I recently "built" my first turbo car. It's 5.3 LM7 from the wrecking yard with a huron speed V3 AC kit and it seems very down on HP compared to other turbo 5.3 builds i've seen online. When I had the car dyno tuned
at 11PSI it only put down 410 RWHP. (My H/C/I Camaro made more power
)
My tuner said it wasn't wanting to make decent power no matter how much he messed with it.
Its running on pump gas nothing fancy, no E85 in my area. all the power dropped off around 6200 RPM.
Its a T56 car with a Hawks 8.8 & 3.27 rear gear.
I've put roughly 2,000 miles on it so far.
Low numbers aside the car runs great. no odd noises, smoking, oil/coolant consumption.
No evidence of the clutch slipping.
Considering doing a compression test here soon, the motor looked well inside and out and it came from a wrecked avalanche.
Its a stock bottom end motor besides the ARP 2000 rod bolts,
Brian tooley racing MLS headgaskets and ARP headbolts.
Walbro 450 and holley boost ref FPR. Deka 80# injectors.
Summit stage 2 turbo Cam 226/230 Dur .600/.575 Lift, 113+4 Lobe Sep
317 Cylinder heads was told they would bump the compression down to somewhere near 8.6:1 which was ideal
LS7 lifters, TSP .660 PAC Dual springs, pushrods, length is correct,
VS Racing 78/75 with a standard exhaust housing.
Looking for some feedback maybe someone else has experienced something similar, if you see anything you would have done differently please share your thoughts.
I recently "built" my first turbo car. It's 5.3 LM7 from the wrecking yard with a huron speed V3 AC kit and it seems very down on HP compared to other turbo 5.3 builds i've seen online. When I had the car dyno tuned
at 11PSI it only put down 410 RWHP. (My H/C/I Camaro made more power
)My tuner said it wasn't wanting to make decent power no matter how much he messed with it.
Its running on pump gas nothing fancy, no E85 in my area. all the power dropped off around 6200 RPM.
Its a T56 car with a Hawks 8.8 & 3.27 rear gear.
I've put roughly 2,000 miles on it so far.
Low numbers aside the car runs great. no odd noises, smoking, oil/coolant consumption.
No evidence of the clutch slipping.
Considering doing a compression test here soon, the motor looked well inside and out and it came from a wrecked avalanche.
Its a stock bottom end motor besides the ARP 2000 rod bolts,
Brian tooley racing MLS headgaskets and ARP headbolts.
Walbro 450 and holley boost ref FPR. Deka 80# injectors.
Summit stage 2 turbo Cam 226/230 Dur .600/.575 Lift, 113+4 Lobe Sep
317 Cylinder heads was told they would bump the compression down to somewhere near 8.6:1 which was ideal
LS7 lifters, TSP .660 PAC Dual springs, pushrods, length is correct,
VS Racing 78/75 with a standard exhaust housing.
Looking for some feedback maybe someone else has experienced something similar, if you see anything you would have done differently please share your thoughts.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
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16 degrees would be low and cause SOME power loss for that low of compression but i would think you should be closer to 500 unless your turning some massive mud tires or something.
Also with that cam you should be peaking closer to 7000.
Also with that cam you should be peaking closer to 7000.
TECH Apprentice
Joined: Feb 2010
Posts: 370
Likes: 138
Graph might help, did you get that compression test done?
brakes hanging?
11psi with that cam in a 5.3 or a 4.8 should be around 700 hp at the crank. You’re down a cylinder or 2
edit didn’t realize your at such a low compression.
8.6:1 you have a 240hp turd on your hands in NA form add 11psi and you got your dyno numbers.
brakes hanging?
11psi with that cam in a 5.3 or a 4.8 should be around 700 hp at the crank. You’re down a cylinder or 2
edit didn’t realize your at such a low compression.
8.6:1 you have a 240hp turd on your hands in NA form add 11psi and you got your dyno numbers.
Last edited by jasons69chevelle; Sep 29, 2022 at 05:50 PM.
Thread Starter
Teching In
Joined: Oct 2018
Posts: 11
Likes: 1
You do make an excellent point, didn't consider that before but it does make alot of sense.
Trying to get a picture of the graph but the cars back in the states and the family is dealing with the hurricane cleanup.
I do plan on shipping it here soon however, looks like a better set of cylinder heads is next after I run a compression test and get some numbers just incase.
I should have done my homework before going with those cylinder heads I was impatient.
Trying to get a picture of the graph but the cars back in the states and the family is dealing with the hurricane cleanup.
I do plan on shipping it here soon however, looks like a better set of cylinder heads is next after I run a compression test and get some numbers just incase.
I should have done my homework before going with those cylinder heads I was impatient.