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Dyno results with 350 HO and suggestions

 
Old 06-12-2019, 11:26 PM
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gotgame
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Default Dyno results with 350 HO and suggestions

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
  • Camshaft Lift (in.): .435 intake / .460 exhaust
  • Camshaft Duration (@.050 in.): 212 intake / 222 exhaust
Edelbrock performer EPS intake 2716
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.
Attached Images
File Type: pdf
dynoc3.pdf (473.6 KB, 13 views)

Last edited by gotgame; 06-13-2019 at 01:56 AM.
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Old 06-13-2019, 12:24 AM
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The temp, altitude, humidity level is not a factor because the dyno inputs the correction factors to perfect sea level conditions. Actually today in Palm Springs real hp might have been something closer to 200.

How to improve your power would be to lean out the air fuel ratio. Get rid of the poorly designed header side pipes. Side pipes are nothing more than a free flowing exhaust system. Nothing tuned about them. The primary tube diameter and length is all wrong to actually be functional.
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Old 06-13-2019, 01:17 AM
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How'd the smog check guy like it?
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Old 06-13-2019, 01:48 AM
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Originally Posted by gkull View Post
The temp, altitude, humidity level is not a factor because the dyno inputs the correction factors to perfect sea level conditions. Actually today in Palm Springs real hp might have been something closer to 200.

How to improve your power would be to lean out the air fuel ratio. Get rid of the poorly designed header side pipes. Side pipes are nothing more than a free flowing exhaust system. Nothing tuned about them. The primary tube diameter and length is all wrong to actually be functional.
Are the dynojets able to correct for that temp? I guess older posts suggested it was topped out at 76 degrees but i suppose that was over a decade ago so maybe it has improved.

As for the exhaust..ughh i really like my sidepipes lol
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Old 06-13-2019, 05:55 AM
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As noted the dyno will correct for conditions so that is a non factor. You are too rich, the headers while not ideal are not going to be a big issue, use them. I suspect if you leaned out the afr to 12.8 you would see 270 hp. The cam change may net you some additional power but I do not see 300 rwhp unless you do some work to get additional flow at higher lift above .500. In other words some head work.

What transmission are you running?

Last edited by bjankuski; 06-13-2019 at 05:58 AM.
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Old 06-13-2019, 08:41 AM
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Originally Posted by gotgame View Post
Are the dynojets able to correct for that temp? I guess older posts suggested it was topped out at 76 degrees but i suppose that was over a decade ago so maybe it has improved.
I've had cars dynoed on dynojets for 25 years and they have always been able to correct for weather. They use barometric pressure, temp and humidity for the correction factor. You can ask the dyno operator for the raw file that was generated and view it in the free viewer on dynojets site. In the viewer you can switch between uncorrected and corrected curves to see how much it actually made.

Last edited by zwede; 06-13-2019 at 08:41 AM.
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Old 06-13-2019, 10:46 AM
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OP
If you're in SoCal w/ 1980 car ... I'm also curious how you "manage" engine mods ... so long as you're aware it can be issue with CA smog regs.

Suggestion:
Sell the good iron Vortec heads.
your 350HO block has a flat tappet cam BUT is already machined to accept OE-type roller cam-lifter kit.
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 GM pn 24502586 HOT CAM for LT1/LT4 ... this has fuel pump eccentric, fits Your 350HO block and is a STEEL billet (Good!) ...
... with 1.6:1 rar, hot cam specs are 218*/228* .525"/.525"
acquire 1.6:1 ratio Rocker Arms for FastBurn heads.
acquire GM pn 19300935 FAST BURN aluminum cylinder heads, 210 in, 78 ex, 62cc chambers, has LS6 springs, fits Your 350HO intake manifold & valve covers.

above will put you over 400HP at crank on pump gas; probably closer to 425-430 ... minus porting costs.
compare above to GM crate ZZ6 pn 19417622 ... BUT above Hot Cam combo has effectively more cam.
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Old 06-13-2019, 10:48 AM
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Originally Posted by bjankuski View Post
As noted the dyno will correct for conditions so that is a non factor. You are too rich, the headers while not ideal are not going to be a big issue, use them. I suspect if you leaned out the afr to 12.8 you would see 270 hp. The cam change may net you some additional power but I do not see 300 rwhp unless you do some work to get additional flow at higher lift above .500. In other words some head work.

What transmission are you running?
thank you. Ill try to lean it out a bit during WOT however right now its runs pretty good A/F ratios during cruise and moderate throttle which is where i spend most of my time. I wont be doing WOT again until the fall as my AC belt isnt aligned perfectly and ive thrown it numerous times above 5000rpms and its getting hot here so AC belt is going on today lol

I have a 700r4 stage 1 from bowtie overdrives

Last edited by gotgame; 06-13-2019 at 11:09 AM.
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Old 06-13-2019, 11:00 AM
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Originally Posted by jackson View Post
OP
If you're in SoCal w/ 1980 car ... I'm also curious how you "manage" engine mods ... so long as you're aware it can be issue with CA smog regs.

Suggestion:
Sell the good iron Vortec heads.
your 350HO block has a flat tappet cam BUT is already machined to accept OE-type roller cam-lifter kit.
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 GM pn 24502586 HOT CAM for LT1/LT4 ... this has fuel pump eccentric, fits Your 350HO block and is a STEEL billet (Good!) ...
... with 1.6:1 rar, hot cam specs are 218*/228* .525"/.525"
acquire 1.6:1 ratio Rocker Arms for FastBurn heads.
acquire GM pn 19300935 FAST BURN aluminum cylinder heads, 210 in, 78 ex, 62cc chambers, has LS6 springs, fits Your 350HO intake manifold & valve covers.

above will put you over 400HP at crank on pump gas; probably closer to 425-430 ... minus porting costs.
compare above to GM crate ZZ6 pn 19417622 ... BUT above Hot Cam combo has effectively more cam.
Ill look into all of that. Considering all my options. Im deciding between a few cams id like your opinion on. Ill post it up separately.

As for southern california.. well i used to have a permanent residence there but i took a job out of state ( physician ) and legit moved out of state and own no property in california, up until more recently I have moved but was still working. I am occasionally asked to attend certain meetings, give lectures to medical students, or go to visit the beach and some of those times I like to drive the corvette through the desert.

I was in town for some meetings( sorta work) and had driven the car when i decide to go on the dyno after talking cars with my buddy who has an old mustang.

So i dont permanently live in CA, car is registered in the state I live , I do like to visit california but other then occasionally punching it in the desert I drive safely and under the speed limit and suprisingly the STS baffles when capped arent that loud so it doesnt catch too much loudness attention when i visit. My colleague was running a loud exhaust driving from nevada to CA recently and got pulled over ( in orange county where they are just waiting for ppl to act stupid on the PCH or with out of state plates lol) so while im not concerned in my state im not trying to get california tickets when i do drive there

The key for me is to have a bag of tools, spare belts, zip ties, duct tape, some wires with electric tape and pay for longer towing through hagerty lol. Other then throwing an AC belt in the middle of no where I havent had any issues going on long drives and the overdrive transmission helps. I installed the sts baffles this past weekend before heading to california so was nervous it may be too loud when cruising at 80 but in overdrive its not at all.

Last edited by gotgame; 06-13-2019 at 11:33 AM.
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Old 06-13-2019, 11:06 AM
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Originally Posted by zwede View Post
I've had cars dynoed on dynojets for 25 years and they have always been able to correct for weather. They use barometric pressure, temp and humidity for the correction factor. You can ask the dyno operator for the raw file that was generated and view it in the free viewer on dynojets site. In the viewer you can switch between uncorrected and corrected curves to see how much it actually made.
Good to know! It will be fun to see what it actually made in that heat lol
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Old 06-13-2019, 11:09 AM
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Originally Posted by gotgame View Post
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
  • Camshaft Lift (in.): .435 intake / .460 exhaust
  • Camshaft Duration (@.050 in.): 212 intake / 222 exhaust
Edelbrock performer EPS intake 2716
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.
My best advice to you is, don't chase dyno numbers. They are what they are and aside from a tuning aide, they really don't matter. Since it will never see a track, you can't chase a time so that leaves seat of the pants feel. Once that is where you want it, you're good! Heads are always the best source of power though but good porting isn't cheap.Your plan will get you there, you've just got to decide if it's worth it.
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Old 06-13-2019, 11:29 AM
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[QUOTE=overBlown;1599575700]My best advice to you is, don't chase dyno numbers. They are what they are and aside from a tuning aide, they really don't matter. Since it will never see a track, you can't chase a time so that leaves seat of the pants feel. Once that is where you want it, you're good! Heads are always the best source of power though but good porting isn't cheap.Your plan will get you there, you've just got to decide if it's worth it.[/QUO

yea you are right. The more i am looking into it is the car is a blast to drive and handles the highway cruising well, is reliable, has some good get up when i hit it and i do feel like im chasing some dyno number a bit. I feel like if i go towards porting i may just be like screw it and get new heads and a new intake etc etc... but at some point i may make it not as great to drive. Right now im getting 20mpg cruising through the desert

Nothing is gonna get done to the car until the fall when it cools down and i can take the AC belt off again. I have some time to think about it. But part of it is the fun of working on the car, seeing how one can make improvements. Im not worried about resale value, its been in the family for a long time and Im not selling it.
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Old 06-13-2019, 11:40 AM
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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
  • 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

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Old 06-13-2019, 11:46 AM
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Originally Posted by gotgame View Post
thank you. Ill try to lean it out a bit during WOT however right now its runs pretty good A/F ratios during cruise and moderate throttle which is where i spend most of my time. lol
The WOT is controlled by the metering rods and not cruising so you can adjust the metering rods will still having a good cruise AFR.
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Old 06-13-2019, 11:49 AM
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Originally Posted by bjankuski View Post
The WOT is controlled by the metering rods and not cruising so you can adjust the metering rods will still having a good cruise AFR.
good to know! Ill switch those back to the stock metering rods. i made that change before i had my wideband sensor hooked up.
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Old 06-13-2019, 12:07 PM
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I like Steel roller cams far more than cast iron. The GM Steel pieces are comparative bargain v. others' Steel options.
That x151 cam is real nice, will fit & run in iron Vortec (350HO) without head mods ... by 350/357 spec, you know what performance to expect ... & it's Steel.
That x586 hot cam /1.6:1 combo a little more lopey but won't work in iron Vortec without some careful attention to clearance (retainer-seal) ... but doable ... it's Steel too.
That comp x264 cam is probably on a cast iron core ... likely available on Steel core but at a premium$.

The hot cam alone (at stock 1.5:1 RAR) is actually more cam (more area under curve) than comp x264 @ 1.5:1 RAR.
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Old 06-13-2019, 12:11 PM
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Originally Posted by jackson View Post
I like Steel roller cams far more than cast iron. The GM Steel pieces are comparative bargain v. others' Steel options.
That x151 cam is real nice, will fit & run in iron Vortec (350HO) without head mods ... by 350/357 spec, you know what performance to expect ... & it's Steel.
That x586 hot cam /1.6:1 combo a little more lopey but won't work in iron Vortec without some careful attention to clearance (retainer-seal) ... but doable ... it's Steel too.
That comp x264 cam is probably on a cast iron core ... likely available on Steel core but at a premium$.

The hot cam alone (at stock 1.5:1 RAR) is actually more cam (more area under curve) than comp x264 @ 1.5:1 RAR.
With the lift of the x151 350/357 cam would you also think new springs/retainers would be needed over the stock 350 HO? I emailed and called GM to inquire about what type of springs they use in that 350/357 but no response. If i could get away with a 27 HP gain with just a straight forward cam swap id be quite happy.
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Old 06-13-2019, 01:30 PM
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If you used that 151 it would work better with your OD (didnt catch what diff gear you have)...if you had some not so crazy port work done youd more than acheive your goal with no drivability loss.
Hot..heck yes about 40 min from you..sure do miss a pool!
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Old 06-13-2019, 01:44 PM
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Drive-train losses are calculated at 15% not 25%!
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Old 06-13-2019, 02:19 PM
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Originally Posted by cuisinartvette View Post
If you used that 151 it would work better with your OD (didnt catch what diff gear you have)...if you had some not so crazy port work done youd more than acheive your goal with no drivability loss.
Hot..heck yes about 40 min from you..sure do miss a pool!

I have a 3.54 rear end ratio. Was a big improvement from the stock 3.08.

Yea that whole area is a like one big oven last few days. I brought a tank top for the drive back lol

I know the lift isnt too much better then the stock flat tappet i have in there, but based on GM's dyno spec sheet it does seem to over much better performance without any other real changes i can see ( from 350 HO vs 350/357 specs). A 27hp gain for just mild cam spec improvement is pretty good.

If the heads have to come off for any reason I can just see what sorta can of worms ill be opening.. " weeelll since i already have the heads off....."
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