Dyno results with 350 HO and suggestions
06-13-2019, 02:58 PM
#21
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
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OP
w/ x151 you might think new springs etc are needed ... but no.
Get yourself a Chevrolet Performance Catalogue ... free pdf download
https://rj-conlin.dcatalog.com/v/201...atalog/?page=1
you can look up the motors & heads & components.
350/357 has same heads & same 80 lb springs & retainers as 350HO ... same iron head Vortec stuff.
check here also ... parts lists for each motor ... keep diggin, info's in there.
https://www.chevrolet.com/performanc...llation-guides
https://www.chevrolet.com/content/da...e-19367080.pdf
https://www.chevrolet.com/content/da...e-19210007.pdf
w/ x151 you might think new springs etc are needed ... but no.
Get yourself a Chevrolet Performance Catalogue ... free pdf download
https://rj-conlin.dcatalog.com/v/201...atalog/?page=1
you can look up the motors & heads & components.
350/357 has same heads & same 80 lb springs & retainers as 350HO ... same iron head Vortec stuff.
check here also ... parts lists for each motor ... keep diggin, info's in there.
https://www.chevrolet.com/performanc...llation-guides
https://www.chevrolet.com/content/da...e-19367080.pdf
https://www.chevrolet.com/content/da...e-19210007.pdf
The following users liked this post:
gotgame (06-13-2019)
06-13-2019, 03:10 PM
#22
OP
w/ x151 you might think new springs etc are needed ... but no.
Get yourself a Chevrolet Performance Catalogue ... free pdf download
https://rj-conlin.dcatalog.com/v/201...atalog/?page=1
you can look up the motors & heads & components.
350/357 has same heads & same 80 lb springs & retainers as 350HO ... same iron head Vortec stuff.
check here also ... parts lists for each motor ... keep diggin, info's in there.
https://www.chevrolet.com/performanc...llation-guides
https://www.chevrolet.com/content/da...e-19367080.pdf
https://www.chevrolet.com/content/da...e-19210007.pdf
w/ x151 you might think new springs etc are needed ... but no.
Get yourself a Chevrolet Performance Catalogue ... free pdf download
https://rj-conlin.dcatalog.com/v/201...atalog/?page=1
you can look up the motors & heads & components.
350/357 has same heads & same 80 lb springs & retainers as 350HO ... same iron head Vortec stuff.
check here also ... parts lists for each motor ... keep diggin, info's in there.
https://www.chevrolet.com/performanc...llation-guides
https://www.chevrolet.com/content/da...e-19367080.pdf
https://www.chevrolet.com/content/da...e-19210007.pdf
The parts list at the bottom..nice!!! I didnt see that initially. Thank you sir.
Well i think thats my best choice so far. The crate engine is fairly new so id hate to tear it down, replace the heads and new intake etc but i can get some reasonably better performance with a roller cam that is a direct swap and wont require too much effort then i think that will be the best option for me in the fall.
Ill take the car back to the same dyno after the swap and see what it runs.
06-13-2019, 03:52 PM
#23
Melting Slicks
You're definitely doing the right thing in going to a roller cam. Flat tappets just aren't worth the risk especially since your block is already machined for it. Good off season project. Enjoy the extra power, peace of mind and cooler idle.
06-13-2019, 04:12 PM
#24
Usually the factor for drivetrain loss in an automatic is right around 80%. Which would put your horsepower at about 325.
But keep in mind, a dyno just spews out a number. It's primary use is to create a baseline and see if you can tune while on the dyno to pull out more power. It really is not an indicator of true horsepower, I believe track numbers are actually more accurate.
But keep in mind, a dyno just spews out a number. It's primary use is to create a baseline and see if you can tune while on the dyno to pull out more power. It really is not an indicator of true horsepower, I believe track numbers are actually more accurate.
06-13-2019, 04:21 PM
#25
Usually the factor for drivetrain loss in an automatic is right around 80%. Which would put your horsepower at about 325.
But keep in mind, a dyno just spews out a number. It's primary use is to create a baseline and see if you can tune while on the dyno to pull out more power. It really is not an indicator of true horsepower, I believe track numbers are actually more accurate.
But keep in mind, a dyno just spews out a number. It's primary use is to create a baseline and see if you can tune while on the dyno to pull out more power. It really is not an indicator of true horsepower, I believe track numbers are actually more accurate.
06-13-2019, 05:42 PM
#26
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
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OP
If you swap that OE 350HO flat tappet cam to the GM x151 roller ... as before, you still have to get the ancillary roller "stuff"
your 350HO block has a flat tappet cam BUT is already machined to accept OE-type roller cam-lifter kit ("stuff").
acquire NEW OE-type hydraulic roller lifters for '97 up OE Vortec 350 rpo L31 vin code 8 ... cheap GM or aftermarket ... do NOT buy "retro-fit" lifters.
acquire OE-type roller cam retention plate-screws, lifter dog bones and spider ... cheap new or used.
acquire an OE-type TIMING SET for '97 up OE Vortec 350 rpo L31 vin code 8 ... cheap GM or aftermarket
OE roller cams have a stepped nose ... that step used in conjuction with roller cam retention plate ... that nose is different from flat tappet cam and also, ...
... the top timing gear fits differently ... hence, different timing set. You will NOT need a fancy double roller timing set.
If you swap that OE 350HO flat tappet cam to the GM x151 roller ... as before, you still have to get the ancillary roller "stuff"
your 350HO block has a flat tappet cam BUT is already machined to accept OE-type roller cam-lifter kit ("stuff").
acquire NEW OE-type hydraulic roller lifters for '97 up OE Vortec 350 rpo L31 vin code 8 ... cheap GM or aftermarket ... do NOT buy "retro-fit" lifters.
acquire OE-type roller cam retention plate-screws, lifter dog bones and spider ... cheap new or used.
acquire an OE-type TIMING SET for '97 up OE Vortec 350 rpo L31 vin code 8 ... cheap GM or aftermarket
OE roller cams have a stepped nose ... that step used in conjuction with roller cam retention plate ... that nose is different from flat tappet cam and also, ...
... the top timing gear fits differently ... hence, different timing set. You will NOT need a fancy double roller timing set.
06-13-2019, 08:00 PM
#27
Melting Slicks
Any thoughts on these 3 cams for driveability, minimal modifications needed to install and performance gain.
This is from the 350/357 GM crate that has basically the same set up as my 350 HO but different cam and is rated at 27 more HP then mine
Or comp cams xr264
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:1,200-5,200
Intake Duration at 050 inch Lift:212
Exhaust Duration at 050 inch Lift:218
Duration at 050 inch Lift:212 int./218 exh.
Advertised Intake Duration:264
Advertised Exhaust Duration:270
Advertised Duration:264 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.487 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.495 in.
Valve Lift with Factory Rocker Arm Ratio:0.487 int./0.495 exh.
Lobe Separation (degrees):110
or LT4 hot cam
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:1,800-5,800
ntake Duration at 050 inch Lift:218
Exhaust Duration at 050 inch Lift:228
Duration at 050 inch Lift:218 int./228 exh.
Advertised Intake Duration:279
Advertised Exhaust Duration:287
Advertised Duration:279 int./287 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.492 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.492 in.
Valve Lift with Factory Rocker Arm Ratio:0.492 int./0.492 exh.
Lobe Separation (degrees):112
Im pretty sure that with all of those im going to have to upgrade the the ls6 springs. If i have to make head modifications i can see me wanting to go down the road of either porting the heads while they are off or just being like screw it lets get new heads and that may not be in my best interest for how i use the car
This is from the 350/357 GM crate that has basically the same set up as my 350 HO but different cam and is rated at 27 more HP then mine
- Camshaft Type (P/N 12677151): Hydraulic roller
- Camshaft Lift (in.): 0.473” intake / 0.473” exhaust
- Camshaft Duration (@.050 in.): 215° intake / 223° exhaust
Or comp cams xr264
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:1,200-5,200
Intake Duration at 050 inch Lift:212
Exhaust Duration at 050 inch Lift:218
Duration at 050 inch Lift:212 int./218 exh.
Advertised Intake Duration:264
Advertised Exhaust Duration:270
Advertised Duration:264 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.487 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.495 in.
Valve Lift with Factory Rocker Arm Ratio:0.487 int./0.495 exh.
Lobe Separation (degrees):110
or LT4 hot cam
Cam Style:Hydraulic roller tappet
Basic Operating RPM Range:1,800-5,800
ntake Duration at 050 inch Lift:218
Exhaust Duration at 050 inch Lift:228
Duration at 050 inch Lift:218 int./228 exh.
Advertised Intake Duration:279
Advertised Exhaust Duration:287
Advertised Duration:279 int./287 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.492 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.492 in.
Valve Lift with Factory Rocker Arm Ratio:0.492 int./0.492 exh.
Lobe Separation (degrees):112
Im pretty sure that with all of those im going to have to upgrade the the ls6 springs. If i have to make head modifications i can see me wanting to go down the road of either porting the heads while they are off or just being like screw it lets get new heads and that may not be in my best interest for how i use the car
06-13-2019, 10:37 PM
#28
I don't want to sound critical - but - I just read that you had ONE pull on the dyno. Honestly, I wouldn't invest anything in cams, heads, upgrades or anything else without a SESSION on the dyno with someone who is capable of tuning your carb and messing with timing. A single pull tells you nothing. It would be the best $200-300 you've spent on the car, and THEN decide if you need upgrades. You might be really surprised.
With timing and some carb tuning - especially if the tune is far off - it would not be unusual to pick up 30-50hp with some changes. This is true especially if you never ran it on an engine dyno. A good shop, bung to plug into Air/Fuel measurements and a half dozen pulls and it may be a different car. Mine definitely was. That, you can do anytime.
Don't be disappointed with what you have until you take it and get a real dyno tune on it. You might be happy with what you have for awhile. Just MHO.
With timing and some carb tuning - especially if the tune is far off - it would not be unusual to pick up 30-50hp with some changes. This is true especially if you never ran it on an engine dyno. A good shop, bung to plug into Air/Fuel measurements and a half dozen pulls and it may be a different car. Mine definitely was. That, you can do anytime.
Don't be disappointed with what you have until you take it and get a real dyno tune on it. You might be happy with what you have for awhile. Just MHO.
Last edited by JoeMinnesota; 06-13-2019 at 10:42 PM.
06-14-2019, 09:02 AM
#29
Drifting
I wouldnt switch to fastburns unless you can find a real good deal on them like I did. I was actually looking at AFRs when I stumbled on to this deal. a 350 with vortec heads can get the power you are wanting but yo may have to go up in RPM. If you are not sure about your valve springs replace them with some spec'd for the cam and heads, its the best option.
06-18-2019, 12:43 AM
#30
Well ive started to collect some parts for my 350 HO flat tappet to roller cam conversion that ill be doing in the fall. Looking at the dyno numbers from some other forums im still deciding between x151 and LT4..but ill decide that closer to the date ill be doing all of these.
Please take a look at the items below and let me know if these are the best parts for the conversion and if theres anything else ill need.
Comp cam retainers
https://www.summitracing.com/parts/cca-787-16
Cloyes timing gear set
https://www.summitracing.com/parts/clo-9-1157
Cam locking plate
https://www.summitracing.com/parts/nal-10168501
Chevy perf roller lifters kit
https://www.summitracing.com/parts/nal-12371042
IF i go LT4 then ls6 springs
https://www.summitracing.com/parts/nal-12499224
Will i need new pushrods?? The ones I have in now are 7.79 https://www.speedwaymotors.com/Chevr...Rod,70556.html
But i think with the taller lifters I may need something smaller like 7.19 https://www.summitracing.com/parts/nal-12371041
Please take a look at the items below and let me know if these are the best parts for the conversion and if theres anything else ill need.
Comp cam retainers
https://www.summitracing.com/parts/cca-787-16
Cloyes timing gear set
https://www.summitracing.com/parts/clo-9-1157
Cam locking plate
https://www.summitracing.com/parts/nal-10168501
Chevy perf roller lifters kit
https://www.summitracing.com/parts/nal-12371042
IF i go LT4 then ls6 springs
https://www.summitracing.com/parts/nal-12499224
Will i need new pushrods?? The ones I have in now are 7.79 https://www.speedwaymotors.com/Chevr...Rod,70556.html
But i think with the taller lifters I may need something smaller like 7.19 https://www.summitracing.com/parts/nal-12371041
06-18-2019, 09:13 AM
#31
Drifting
Well ive started to collect some parts for my 350 HO flat tappet to roller cam conversion that ill be doing in the fall. Looking at the dyno numbers from some other forums im still deciding between x151 and LT4..but ill decide that closer to the date ill be doing all of these.
Please take a look at the items below and let me know if these are the best parts for the conversion and if theres anything else ill need.
Comp cam retainers
https://www.summitracing.com/parts/cca-787-16
Cloyes timing gear set
https://www.summitracing.com/parts/clo-9-1157
Cam locking plate
https://www.summitracing.com/parts/nal-10168501
Chevy perf roller lifters kit
https://www.summitracing.com/parts/nal-12371042
IF i go LT4 then ls6 springs
https://www.summitracing.com/parts/nal-12499224
Will i need new pushrods?? The ones I have in now are 7.79 https://www.speedwaymotors.com/Chevr...Rod,70556.html
But i think with the taller lifters I may need something smaller like 7.19 https://www.summitracing.com/parts/nal-12371041
Please take a look at the items below and let me know if these are the best parts for the conversion and if theres anything else ill need.
Comp cam retainers
https://www.summitracing.com/parts/cca-787-16
Cloyes timing gear set
https://www.summitracing.com/parts/clo-9-1157
Cam locking plate
https://www.summitracing.com/parts/nal-10168501
Chevy perf roller lifters kit
https://www.summitracing.com/parts/nal-12371042
IF i go LT4 then ls6 springs
https://www.summitracing.com/parts/nal-12499224
Will i need new pushrods?? The ones I have in now are 7.79 https://www.speedwaymotors.com/Chevr...Rod,70556.html
But i think with the taller lifters I may need something smaller like 7.19 https://www.summitracing.com/parts/nal-12371041
06-18-2019, 07:22 PM
#32
Le Mans Master
Member Since: Sep 2001
Location: Unreconstructed, South Carolina
Posts: 7,739
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Yes, you'll need shorter PRs; with OE type roller lifters they'll need to be ABOUT 7.2"
Q? Which rocker arms will you use? Those 350HO stamped rockers you already have? Or something else? What?
FWIW ... RAs with NO roller at tip are far more forgiving to minor PR length variance.
If you run a roller RA or roller-tip RA, you Must perform the geometry-PR measurement process.
Unless you retro-fit your Vortec heads with PR guideplates, you Must use self-aligning aka self-guided RAs (OE Vortec RAs are s-a / s-g)
you'll need retainers only if you change to beehive springs.
that timing set is a great choice.
FWIW I budget as well as prefer quality; budget may be of less concern to you.
Locking plate OK ... but ...
The Lifters' RETAINER-CLIP "stuff" can be had brand new by good EngineQuest for about $50.
https://www.ebay.com/itm/Chevrolet-3...oAAOSw3h1ZSYX~
You're aware Chev/GM/Ford etc do Not MANUFACTURE lifters, right?
Do Not compromise on lifter quality ... do Not risk asian lifters ... same for roller rockers.
fleabay & amazombie have USA OE roller lifters for ~ $150 / 16. Look-Verify USA.
https://www.ebay.com/itm/Set-of-16-U...pe!29501!US!-1
06-18-2019, 09:04 PM
#33
Burning Brakes
I started with almost the same engine that you have. My Vette came with the 300 hp version of your engine(same cam non vortec heads). I changed the heads to an older set of AFR 195's and bought the Comp XR 274HR "K" kit that included the cam, lifters, pushrods, and springs. I bought the lifter and cam retainers from Summit (your block is already drilled for them).
With my 3.73 gears and Hooker side pipes with STS baffles it became a whole different(better) car to drive. Someday I'll get it on the dyno.
With my 3.73 gears and Hooker side pipes with STS baffles it became a whole different(better) car to drive. Someday I'll get it on the dyno.
Last edited by Crimson Thunder; 06-18-2019 at 09:04 PM.
06-18-2022, 03:47 AM
#34
Any updates on you 350 ho crate?
Hey, I know this is a 3 y/o poat.. But I got same motor and hope to hear if did any more work to the 350 ho...
So, I have the same 35p ho crate installed in my 88 K1500 4spd (low granny) rcsb. Even with 33x12.5x15 mud tires, can do burnouts n would walk 2000ish 4.6 poopstangs easily once the secondary opened up. Felt like a damn turbo kicking in 😆.
So, have you done more to the motor? Hoping you added the zz4 cam since 3 years ago. I'm very curious of hp difference. I know the hear sucks out there like here in FL. I was stationed in Pendleton/SoCal from 2010-2014. Before I got out of the Marines and moved back home, I started working in Santee at TheBestDyno.com ( not the dyno shop which was like .5 mile down the road) . I dyno tuned and other performance work. BTW, I'm really hoping to get a later c3 like yours for an LS swap. Missed out buying a trophy 81 back in 2003 for my high school graduation. Been a throne in my side since not owning one. Soon hopefully. But I got a project 86 for $600 with Locked up L98. So been thinking about using the zz4 cam in a L31 long block i have laying around. Or stock/oe LT1 cam from a 97 F car. Depending if I'm gonna keep this c4 or not.
So, I have the same 35p ho crate installed in my 88 K1500 4spd (low granny) rcsb. Even with 33x12.5x15 mud tires, can do burnouts n would walk 2000ish 4.6 poopstangs easily once the secondary opened up. Felt like a damn turbo kicking in 😆.
So, have you done more to the motor? Hoping you added the zz4 cam since 3 years ago. I'm very curious of hp difference. I know the hear sucks out there like here in FL. I was stationed in Pendleton/SoCal from 2010-2014. Before I got out of the Marines and moved back home, I started working in Santee at TheBestDyno.com ( not the dyno shop which was like .5 mile down the road) . I dyno tuned and other performance work. BTW, I'm really hoping to get a later c3 like yours for an LS swap. Missed out buying a trophy 81 back in 2003 for my high school graduation. Been a throne in my side since not owning one. Soon hopefully. But I got a project 86 for $600 with Locked up L98. So been thinking about using the zz4 cam in a L31 long block i have laying around. Or stock/oe LT1 cam from a 97 F car. Depending if I'm gonna keep this c4 or not.
Took the car to the dyno for the first time today. It was 106 degrees today at 6pm. Made 260HP and 295 TQ Results attached
Specs
1980 Corvette
350 HO crate rated at 330HO and 380 TQ
cam that came with it was
Edelbrock 1406 carb with 1 power size up on the metering rods
Dougs headers and side pipes with 1 7/8 primaries and 4 inch collectors
STS baffles capped
700R4 transmission
HEI dist
timing at 34 degrees mechanical all in by 2800rpms
electrics fans
3.54 rear end
Assuming 25% drivetrain loss this puts me at about 350ish for HP which is more then the crate is originally rated for and not too bad considering it was 106 degrees out when it was done.
I drive this car a lot on the highway to work and it will never see the track. With that said Id like to get a bit more out of it ( dont we always) get keep it fun to drive when cruising.
Id like to keep the vortec heads as my intake ( performer EPS 2716) is for that and id rather not change my intake. Ill probably change my metering rod back to stock as its a bit rich but not too bad.
I am considering upgrading to Comp Cams XR264HR along with ls6 springs to get my lift to about .48 and .49ish.
Aside from maybe porting the vortec heads and helping with that exhaust side a bit which im not sure about and waiting on a quote for that.
Any other suggestions to increase HP by about 30-40? Id really like 300 RWHP out of this engine. Its possible that the temp today killed some power.
Specs
1980 Corvette
350 HO crate rated at 330HO and 380 TQ
cam that came with it was
- Camshaft Lift (in.): .435 intake / .460 exhaust
- Camshaft Duration (@.050 in.): 212° intake / 222° exhaust
Edelbrock 1406 carb with 1 power size up on the metering rods
Dougs headers and side pipes with 1 7/8 primaries and 4 inch collectors
STS baffles capped
700R4 transmission
HEI dist
timing at 34 degrees mechanical all in by 2800rpms
electrics fans
3.54 rear end
Assuming 25% drivetrain loss this puts me at about 350ish for HP which is more then the crate is originally rated for and not too bad considering it was 106 degrees out when it was done.
I drive this car a lot on the highway to work and it will never see the track. With that said Id like to get a bit more out of it ( dont we always) get keep it fun to drive when cruising.
Id like to keep the vortec heads as my intake ( performer EPS 2716) is for that and id rather not change my intake. Ill probably change my metering rod back to stock as its a bit rich but not too bad.
I am considering upgrading to Comp Cams XR264HR along with ls6 springs to get my lift to about .48 and .49ish.
Aside from maybe porting the vortec heads and helping with that exhaust side a bit which im not sure about and waiting on a quote for that.
Any other suggestions to increase HP by about 30-40? Id really like 300 RWHP out of this engine. Its possible that the temp today killed some power.
06-18-2022, 07:37 AM
#35
Race Director
he hasn't been on the forum since 9-9-2019. send him a pm. he may see the email notifier he got a PM. otherwise you making all of us read 3 year old stuff until we check the posting date. 3rd gen is more of a gearhead site. you may find more answers there.