112 deg cam with turbo - can it work?
03-01-2018, 02:03 PM
#1
112 deg cam with turbo - can it work? Looking to do a budget turbo build on my LQ4 powered 1981 Z28. Currently the motor has a Crane 228/232 .600/.600 cam on a 112 deg. Looking to use an On3 76/75 or similar turbo and looking for 500+rwhp though an auto for now. The idea is that it's budget and will be my first foray into forced induction. Looking at the sloppy mechanics and they use some 112 deg. cams for their 500rwhp builds with similar sized turbos. Other info I've found suggests that if backpressure is minimized, then an N/A turbo cam will work just fine.
Q- would I be able to reach my 500rwhp goal with my current cam even though it's probably not ideal then once I get some experience swap a dedicated turbo cam in later? If it helps I plan on using a 4" down pipe and no muffler to reduce backpressure.
Any real world experience form anyone who could chime in.
Any info is greatly appreciated.
Q- would I be able to reach my 500rwhp goal with my current cam even though it's probably not ideal then once I get some experience swap a dedicated turbo cam in later? If it helps I plan on using a 4" down pipe and no muffler to reduce backpressure.
Any real world experience form anyone who could chime in.
Any info is greatly appreciated.
03-01-2018, 02:34 PM
#3
Yeah that power number is based on lower boost levels and I can't see it being too hard to hit but I wonder how boost will come on etc. Provided the turbo is sized right for the motor would a 112 cam make power delivery, that would otherwise be smooth with an FI cam, peaky or create a scenario where I'd hit a "boost wall" or similar reaction when turned up a bit?
03-01-2018, 03:14 PM
#4
The LSA by itself doesn't mean much. You can run a 110 LSA and be fine depending on the valve events. You're cam is on the big side duration wise for a higher back pressure setup. But as said it will be fine for 500hp. You could install a much smaller cam and still hit your goal easily with more low end power and drive-ability/mileage etc..
03-01-2018, 04:15 PM
#6
Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 7.0 BTDC 41.0 ABDC 107 228.0
Exhaust 53.0 BBDC (1.0) BTDC 117 232.0
Looks like overlap is 68* which is rather high. Can I use a 78/75 for better results and more potential down the road?
Last edited by Zedzag; 03-01-2018 at 04:41 PM.
Trending Topics
03-01-2018, 07:08 PM
#8
my cam is 111 +4....it was spec'd by ljms for my ls3 headed 6.0.....it lights off awesome and has no shortage of power.
you will be fine.
if you really want less the 600 hp I'd leave the stock cam in it
you will be fine.
if you really want less the 600 hp I'd leave the stock cam in it
03-01-2018, 10:21 PM
#9
Add the intake and exhaust adv durations
Divide the results by 4
Subtract the LSA
Multiply the results by 2
Other use .050 duration where the overlap ends up at 6*:
(Intake Duration + Exhaust Duration /2) -(2xLSA)
I'm getting confused but 6* indicates low overlap which should suggest that boost isn't being blown right out the exhaust but 68* looks like it would. Are these really saying the same thing just a matter of adv vs .050?
Last edited by Zedzag; 03-01-2018 at 10:46 PM. Reason: added info
03-01-2018, 11:20 PM
#11
Looking to do a budget turbo build on my LQ4 powered 1981 Z28. Currently the motor has a Crane 228/232 .600/.600 cam on a 112 deg. Looking to use an On3 76/75 or similar turbo and looking for 500+rwhp though an auto for now. The idea is that it's budget and will be my first foray into forced induction. Looking at the sloppy mechanics and they use some 112 deg. cams for their 500rwhp builds with similar sized turbos. Other info I've found suggests that if backpressure is minimized, then an N/A turbo cam will work just fine.
Q- would I be able to reach my 500rwhp goal with my current cam even though it's probably not ideal then once I get some experience swap a dedicated turbo cam in later? If it helps I plan on using a 4" down pipe and no muffler to reduce backpressure.
Any real world experience form anyone who could chime in.
Any info is greatly appreciated.
Q- would I be able to reach my 500rwhp goal with my current cam even though it's probably not ideal then once I get some experience swap a dedicated turbo cam in later? If it helps I plan on using a 4" down pipe and no muffler to reduce backpressure.
Any real world experience form anyone who could chime in.
Any info is greatly appreciated.
03-02-2018, 09:33 AM
#13
I don’t think boost would be high enough for back pressure to be an issue at 500ish hp with a 75mm turbine T4 on a 6.0. Probably making 400ish crank as it sits. I agree though... why bother with a T4, esp. on a 6.0. I'd jump right into a T6. The 1.32 T6 S475 clone at VSracing is on sale for like $409 I believe.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.
03-02-2018, 09:37 AM
#14
Restricted User
I don’t think boost would be high enough for back pressure to be an issue at 500ish hp with a 75mm turbine T4 on a 6.0. Probably making 400ish crank as it sits.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.
I know it doesn't matter much for 500 HP, but we both know very well that 500 HP won't matter very much for long, either.
03-02-2018, 09:43 AM
#15
9 Second Club
He only wants 500hp...that's like no boost. If backpressure is causing a problem on something making almost no boost...something is drastically wrong.
Just run it, it will be fine.
03-02-2018, 09:48 AM
#16
Restricted User
03-02-2018, 09:54 AM
#17
Just imagine someone going hahahahaha in your face until they run out of breath. This is how little your cam is a problem for your build goal. You will likely find that a cam swap always ends up at the very bottom of the list of things to make your engine better once you put it on the street. BTW, this is not saying a cam is not important. It is just that you have such a middle of the road type cam that it won't be the deciding factor in almost anything you change.
03-02-2018, 10:01 AM
#19
I don’t think boost would be high enough for back pressure to be an issue at 500ish hp with a 75mm turbine T4 on a 6.0. Probably making 400ish crank as it sits. I agree though... why bother with a T4, esp. on a 6.0. I'd jump right into a T6. The 1.32 T6 S475 clone at VSracing is on sale for like $409 I believe.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.
No such thing as a true zero overlap cam. Most overlap calculators use advertised duration which will always have a much higher overlap number. Turbo guys plug in the duration @ .050 for a guess guess at an acceptable cam for a moderate street/strip setups with highish back pressures. The goal is to keep the overlap @ .050 at zero or less. The higher the negative overlap the better the cam for higher back pressure setups. This usually provides a somewhat boost friendly cam.