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LS3 Carbed build

General engine tech -- Drag Racing to Circle Track

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CGT
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Re: LS3 Carbed build

Post by CGT » Sun Oct 20, 2019 9:31 pm

An update. The engine was making 710-725 hp at 7500rpm, new GZ vacuum pump locked up, 700 hp 550 tq on VP C12 with no vacuum now. It's still on the dyno for the next couple days. Hopefully I can get a new pump or rebuild kit quick for testing. I will keep everyone up to date.
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Re: LS3 Carbed build

Post by swampbuggy » Sun Oct 20, 2019 9:59 pm

CGT your H.P. comes in at 1.9 H.P./ C.I., that is impressive, your combo must be pretty darn close. Mr. Frankshaft was almost dead on with his estimate back in Nov. of 2017 on page 1 of this discussion. Congrat's friend on your build, Mark H. =D> This shows the LS-3 cyl. head has great potential.

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Re: LS3 Carbed build

Post by MadBill » Sun Oct 20, 2019 10:12 pm

CGT wrote:
Sun Oct 20, 2019 9:31 pm
An update. The engine was making 710-725 hp at 7500rpm, new GZ vacuum pump locked up, 700 hp 550 tq on VP C12 with no vacuum now. It's still on the dyno for the next couple days. Hopefully I can get a new pump or rebuild kit quick for testing. I will keep everyone up to date.
Can you narrow down what effect vacuum has on your engine when you're making noise again? I've observed results in the range of 12-15 HP on ~ 450 HP 6500 RPM engines with no special rings, but I've heard/read of results of anywhere from zero to 50 HP, the latter from Big Joe Sherman.
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Re: LS3 Carbed build

Post by n2xlr8n » Mon Oct 21, 2019 11:58 am

I've been following this one for a while- figured it would rip.

Very nice job, sir.
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Re: LS3 Carbed build

Post by CGT » Mon Oct 21, 2019 12:28 pm

"Never let your hobby ride you. Work while you work and play while you play"

"Hobbies are a contradiction; they take work and turn it into leisure, and take leisure and turn it into work."

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Re: LS3 Carbed build

Post by randy331 » Mon Oct 21, 2019 12:50 pm

Nice clean sounding hyd valve train up there at 7000+ rpm.

I'd like to see a .800"-.900" lift solid roller in it using some lobes with some speed.

A sheet metal intake with a pair of 4825 Braswells on it, or 2 of those Whitener 1050s ???

That black carb I sent out for testing may be a little big for a pair of them ??? :D

It's a good sign all the carbs need jet taken out for best power.

Randy

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Re: LS3 Carbed build

Post by steve cowan » Mon Oct 21, 2019 2:39 pm

randy331 wrote:
Mon Oct 21, 2019 12:50 pm
Nice clean sounding hyd valve train up there at 7000+ rpm.

I'd like to see a .800"-.900" lift solid roller in it using some lobes with some speed.

A sheet metal intake with a pair of 4825 Braswells on it, or 2 of those Whitener 1050s ???

That black carb I sent out for testing may be a little big for a pair of them ??? :D

It's a good sign all the carbs need jet taken out for best power.

Randy
Randy,
in your opinion,is there a common factor that you see when an engine is more fuel efficient and makes more power with less fuel
eg- chamber design,valve events,valve job or a combination of everything.
as far as LS3 is that a normal trend you see.
steve c

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Re: LS3 Carbed build

Post by CGT » Tue Oct 22, 2019 8:38 am

Resized_20191022_062114.jpg
Resized_20191022_062050.jpg
Resized_20191022_062143.jpg
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"Never let your hobby ride you. Work while you work and play while you play"

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Re: LS3 Carbed build

Post by CGT » Tue Oct 22, 2019 9:35 am

MadBill wrote:
Sun Oct 20, 2019 10:12 pm
Can you narrow down what effect vacuum has on your engine when you're making noise again? I've observed results in the range of 12-15 HP on ~ 450 HP 6500 RPM engines with no special rings, but I've heard/read of results of anywhere from zero to 50 HP, the latter from Big Joe Sherman.
Well Bill, I've seen the effects of vacuum be anywhere from zero to over 20. It seems bigger, nicer oil pans with more overall volume gain less...but not always... its always kind of humbling to find out

As far as my LS3 goes, a string of circumstances with my dyno session is gonna end up making some of my tests foggy. I looked back through some pulls, I hooked the vacuum pump up after a couple pulls when I felt like the engine was broke in. It looks like it added about 15hp at the top of the pulls at that point.

But the motor wasn't fully tuned up and was making under 700hp. After some timing loops, and trimming some fuel it was at around 720....then the load sensor on the dyno failed. After replacing the load sensor and other dyno repairs, recalibrating the torque arm...4 hrs later... I am warming up the engine to make sure it repeats itself after replacing the failed sensor...and the vacuum pump locks up at idle :oops: . 700hp now without.

I wouldn't be surprised if it was 20ish horsepower on this engine but until I can get my pump back on it and back the 720 pulls up I'd be reluctant to say exactly( to the tee)….but it definitely added. Doesn't look like GZ wants to overnight me a new pump(warranty) to finish my testing with....so that will remain semi-unanswered I suppose. Its somewhere between 15-25hp on this engine.
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Re: LS3 Carbed build

Post by CGT » Tue Oct 22, 2019 10:07 am

randy331 wrote:
Mon Oct 21, 2019 12:50 pm
Nice clean sounding hyd valve train up there at 7000+ rpm.
Very very clean sounding and repeatable. RWTECH on here had some great tips and advice on component selection from his work with these stock valvetrain parts for GM. He has told me that my stuff should be fine at 8000 if the cam lobes aren't junk. I made a couple pulls to 7700 and it sounded just as clean there...so maybe it would. I brought some thinner oil to try, but was reluctant to rock the boat with the valvetrain being so happy.
randy331 wrote:
Mon Oct 21, 2019 12:50 pm
I'd like to see a .800"-.900" lift solid roller in it using some lobes with some speed.
For sure! What would you predict happening to the peaks with a change like that? These hydraulic lobes I used didn't have much area or speed.
randy331 wrote:
Mon Oct 21, 2019 12:50 pm
It's a good sign all the carbs need jet taken out for best power.
Craziest thing I've ever seen. 3 good carbs all needing 8 or more jet sizes pulled out of them....definitely didn't hurt my feelings any. :D . My budget 8896 1050 that Mark tuned up for me ran really really good on that engine. Wish I would of had the jets to get the bigger carbs leaned down enough.
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Re: LS3 Carbed build

Post by randy331 » Tue Oct 22, 2019 1:44 pm

steve cowan wrote:
Mon Oct 21, 2019 2:39 pm
randy331 wrote:
Mon Oct 21, 2019 12:50 pm
Nice clean sounding hyd valve train up there at 7000+ rpm.

I'd like to see a .800"-.900" lift solid roller in it using some lobes with some speed.

A sheet metal intake with a pair of 4825 Braswells on it, or 2 of those Whitener 1050s ???

That black carb I sent out for testing may be a little big for a pair of them ??? :D

It's a good sign all the carbs need jet taken out for best power.

Randy
Randy,
in your opinion,is there a common factor that you see when an engine is more fuel efficient and makes more power with less fuel
eg- chamber design,valve events,valve job or a combination of everything.
as far as LS3 is that a normal trend you see.
I haven't seen any dyno data yet on overflowZZ, so I don't know what the bsfc #s are but I'm sure they are good cause it makes good power.

I was talkin about what Chad said in his post above, putting on a known good carb that had jetting correct for other engines on an engine and having to take jet out says it's a good induction tract. It's producing good carb signal and pulling the fuel it needs through a smaller jet. That in general is a good sign.

As far as BSFC in general, good induction tracts help those too. Steeper seat stuff seem to have better BSFC #s.

You only have 2 ways to make power,... fuel flow and BSFC #s.

Randy

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Re: LS3 Carbed build

Post by randy331 » Tue Oct 22, 2019 1:48 pm

CGT wrote:
Tue Oct 22, 2019 10:07 am

randy331 wrote:
Mon Oct 21, 2019 12:50 pm
I'd like to see a .800"-.900" lift solid roller in it using some lobes with some speed.
For sure! What would you predict happening to the peaks with a change like that? These hydraulic lobes I used didn't have much area or speed.
I think the induction tract will respond well to lift/area. I'd expect both peaks to move to a higher rpm and make more power. I'd expect a bigger increase in HP vs TQ. More TQ will be hard to get. RPM will help the HP.

Randy

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Re: LS3 Carbed build

Post by slo-svt » Tue Oct 22, 2019 1:52 pm

randy331 wrote:
Tue Oct 22, 2019 1:44 pm

I haven't seen any dyno data yet on overflowZZ, so I don't know what the bsfc #s are but I'm sure they are good cause it makes good power.

Randy
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Re: LS3 Carbed build

Post by CGT » Tue Oct 22, 2019 2:21 pm

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Re: LS3 Carbed build

Post by MadBill » Tue Oct 22, 2019 3:43 pm

CGT wrote:
Tue Oct 22, 2019 9:35 am
MadBill wrote:
Sun Oct 20, 2019 10:12 pm
Can you narrow down what effect vacuum has on your engine when you're making noise again? I've observed results in the range of 12-15 HP on ~ 450 HP 6500 RPM engines with no special rings, but I've heard/read of results of anywhere from zero to 50 HP, the latter from Big Joe Sherman.
Well Bill, I've seen the effects of vacuum be anywhere from zero to over 20. It seems bigger, nicer oil pans with more overall volume gain less...but not always... its always kind of humbling to find out

As far as my LS3 goes, a string of circumstances with my dyno session is gonna end up making some of my tests foggy. I looked back through some pulls, I hooked the vacuum pump up after a couple pulls when I felt like the engine was broke in. It looks like it added about 15hp at the top of the pulls at that point.

But the motor wasn't fully tuned up and was making under 700hp. After some timing loops, and trimming some fuel it was at around 720....then the load sensor on the dyno failed. After replacing the load sensor and other dyno repairs, recalibrating the torque arm...4 hrs later... I am warming up the engine to make sure it repeats itself after replacing the failed sensor...and the vacuum pump locks up at idle :oops: . 700hp now without.

I wouldn't be surprised if it was 20ish horsepower on this engine but until I can get my pump back on it and back the 720 pulls up I'd be reluctant to say exactly( to the tee)….but it definitely added. Doesn't look like GZ wants to overnight me a new pump(warranty) to finish my testing with....so that will remain semi-unanswered I suppose. Its somewhere between 15-25hp on this engine.
Thanks CGT. Hope you're up and running again soon! BTW the engines I mentioned were all dry sump.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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