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LS3 Carbed build

General engine tech -- Drag Racing to Circle Track

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gmrocket
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Re: LS3 Carbed build

Post by gmrocket »

CGT wrote: Sun Feb 02, 2020 3:01 pm
steve cowan wrote: Sun Feb 02, 2020 1:01 pm i think it just proves that valve events only work in a narrow set of parameters like rpm,engine load etc.
For sure. The "perfect" cam if there is such a thing, can only be for a snapshot at a time through a given range. The wider the range your operating in, the more this becomes evident. And cam position can be like that also...until you get enough of the events out of whack that it just gives up everywhere :shock: ....I think itd be pretty easy to make a solid roller better from start to finish on this this thing though, but im sure that could be humbling.

Cam 1 ran the best as far as averages at about 108ICL, and Cam 2 around 107ICL(I say "around" because its a hex adjust, if youve had experience with them lol) I backed cam 2 up to around 111 and it hurt power from 5000 all the way to 8200. Cam 1 and 2 in the positions that produced the best average power had nearly the same IVC in common..

I pretty much got all my tests in that I wanted except the low viscosity synthetic oil. I didn't have the balls to put thin oil in it with the hydraulics and 8200 rpm stuff.
steve cowan wrote: Sun Feb 02, 2020 1:01 pm is it possible that spring rate and cam worked in better sync at higher rpms
Randy brought up a good point about cam 2. Same lobe family, same lobe lift....longer duration(cam 2) should be slightly tamer...and that could be responsible for how things smoothed out some up above 7000.

But im looking at my 4-1 header test now and its considerably smoother up there also, which could mean something is going out of tune up there with the try y's. Or that since the 4-1's were down on power it just looks smoother because there is less power on either side of the zigs and zags. 8).....more questions...
Have you got a good clear pic of the tri-y's

And what are the step dia's?
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Re: LS3 Carbed build

Post by CGT »

gmrocket wrote: Mon Feb 03, 2020 1:34 pm
CGT wrote: Sun Feb 02, 2020 3:01 pm
steve cowan wrote: Sun Feb 02, 2020 1:01 pm i think it just proves that valve events only work in a narrow set of parameters like rpm,engine load etc.
For sure. The "perfect" cam if there is such a thing, can only be for a snapshot at a time through a given range. The wider the range your operating in, the more this becomes evident. And cam position can be like that also...until you get enough of the events out of whack that it just gives up everywhere :shock: ....I think itd be pretty easy to make a solid roller better from start to finish on this this thing though, but im sure that could be humbling.

Cam 1 ran the best as far as averages at about 108ICL, and Cam 2 around 107ICL(I say "around" because its a hex adjust, if youve had experience with them lol) I backed cam 2 up to around 111 and it hurt power from 5000 all the way to 8200. Cam 1 and 2 in the positions that produced the best average power had nearly the same IVC in common..

I pretty much got all my tests in that I wanted except the low viscosity synthetic oil. I didn't have the balls to put thin oil in it with the hydraulics and 8200 rpm stuff.
steve cowan wrote: Sun Feb 02, 2020 1:01 pm is it possible that spring rate and cam worked in better sync at higher rpms
Randy brought up a good point about cam 2. Same lobe family, same lobe lift....longer duration(cam 2) should be slightly tamer...and that could be responsible for how things smoothed out some up above 7000.

But im looking at my 4-1 header test now and its considerably smoother up there also, which could mean something is going out of tune up there with the try y's. Or that since the 4-1's were down on power it just looks smoother because there is less power on either side of the zigs and zags. 8).....more questions...
Have you got a good clear pic of the tri-y's

And what are the step dia's?
The tri-y's are 1.75 to 1.875 primary, the 4-1's 1.875 straight 3.5" collector.
Screenshot (42).png
Screenshot (43).png
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gmrocket
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Re: LS3 Carbed build

Post by gmrocket »

Thanks
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Re: LS3 Carbed build

Post by CGT »

gmrocket wrote: Mon Feb 03, 2020 2:22 pmThanks
I need to do some measuring of lengths etc. I can shoot them to you when I do if your interested.
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Re: LS3 Carbed build

Post by gmrocket »

CGT wrote: Mon Feb 03, 2020 2:28 pm
gmrocket wrote: Mon Feb 03, 2020 2:22 pmThanks
I need to do some measuring of lengths etc. I can shoot them to you when I do if your interested.
I am ... when you get a chance

Is the 4 to 1 a straight 3.5" collector?
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Re: LS3 Carbed build

Post by CGT »

gmrocket wrote: Mon Feb 03, 2020 2:46 pm Is the 4 to 1 a straight 3.5" collector?
Yes, straight no merge.
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Re: LS3 Carbed build

Post by randy331 »

The try Y headers exit the ex ports at a nice angle.
Likely that helps the try Ys.

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Re: LS3 Carbed build

Post by GARY C »

CGT wrote: Sat Feb 01, 2020 7:53 pm https://youtu.be/iOOuUug-wOU
I may have missed it but did you get to retest with and without the new vac pump?
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Re: LS3 Carbed build

Post by zums »

The Hydraulic Monster, nice f'n job, any collector testing with the 4 to 1s, did you happen to try a 3"collector
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Re: LS3 Carbed build

Post by CGT »

zums wrote: Mon Feb 03, 2020 7:41 pm did you happen to try a 3"collector
No I didn't, but it was on my mind. I told myself that if the 4-1's looked promising, I was gonna go down that road....but they just weren't good enough anywhere for me to get excited about playing with them. Plus, that test was the end of day 2 on the dyno, 3 really for me if you count me putting it on Thursday. Everyone was tired. The only thing anyone wanted to see at that point was to pull it to 8500rpm, and I held strong against that....so.....

I'm just curious what you would have to do to some 4-1 headers to run with these tri y's or be better. Maybe 1.75 up to 1.875 to 2 inch....keep them real short with a merge collector...2.5" choke...I don't really know.
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Re: LS3 Carbed build

Post by steve316 »

Chad a merge collector with 2.5 choke will want less jet. most of the time make the same power but go down the track quicker. Not sure of reason, just what I have experienced.
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Re: LS3 Carbed build

Post by CGT »

steve316 wrote: Tue Feb 04, 2020 9:44 am Chad a merge collector with 2.5 choke will want less jet. most of the time make the same power but go down the track quicker. Not sure of reason, just what I have experienced.
Hey Steve. My thinking was if the 4-1 test showed some promise up top, I would experiment with a merge/choke to try to bring the rest of the curve around... Im sure my thinking could be flawed.

Less jet than a #85 jet in a 1050 dominator with no power valves? :D
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Re: LS3 Carbed build

Post by randy331 »

CGT wrote: Tue Feb 04, 2020 10:12 am Less jet than a #85 jet in a 1050 dominator with no power valves? :D
That is a good sign .

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Re: LS3 Carbed build

Post by CGT »

Screenshot (44).png



This what the 4-1's looked like comparing corrected horsepower: From the left Pull 56 is Tri-y's with cam 2 backed up to 111° ICL(which hurt power), next pull over pull 57 is a backup pull to pull 56. Pull 58 is the switch to 4-1 header, pull 59 is a backup to pull 58.
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Last edited by CGT on Tue Feb 04, 2020 11:13 am, edited 1 time in total.
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Re: LS3 Carbed build

Post by CGT »

Screenshot (45).png


Same pull arrangement, this one showing corrected torque.
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