Large Vortec bowtie, Engine?

General engine tech -- Drag Racing to Circle Track

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6.50camaro
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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Sun Sep 23, 2018 2:20 pm

He is rules limited to 9.8 static CR . The way the setup is now the dynamic CR is just over 7.1 to 1 . A .020 thinner head gasket and getting the IVC (on the seat) to 60° or sooner abdc will jump his dynamic CR up over 8.0 to 1 . I think there is alot that can been done without major investment of capital. Dan

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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Sun Sep 23, 2018 2:32 pm

Passing the whistle machine test and the real CR are 2 different things. Get creative... Especially if you know which cylinder they are going to test. The front runners are...;-)

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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Sun Sep 23, 2018 3:09 pm

F-BIRD'88 wrote:
Sun Sep 23, 2018 2:32 pm
Passing the whistle machine test and the real CR are 2 different things. Get creative... Especially if you know which cylinder they are going to test. The front runners are...;-)
Like the last short block i took apart (not my build) where #1 rod had an offset bushing for the wrist pin keeping that one piston .025 further in the hole than the rest .
Sorry but i don't agree with you on this one . The reputation as a cheater is hard to shake after getting caught . Dan

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Sun Sep 23, 2018 5:15 pm

After the most recent race it clearly needs torque in the 4000-5500 area, really not responsive in that rpm range but then comes alive in the straightaway

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Re: Large Vortec bowtie, Engine?

Post by rustbucket79 » Sun Sep 23, 2018 5:34 pm

Do you have the valve to piston clearance to advance the cam? Pretty cheap to do this.

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Sun Sep 23, 2018 6:00 pm

Was thinking of pulling the topend off here soon, and check PV clearance when I install a thinner head gasket. Can this be achieve with a 9 keyway double roller timing set?

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Sun Sep 23, 2018 6:16 pm

My other consideration is we have a rev limit at 7000 rpm. And it was hitting just about where it needs to be going into the turn.

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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Sun Sep 23, 2018 6:44 pm

No, degree the cam and move it the req degrees to get it right. Those 9 key timing gears are rough at best.

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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Sun Sep 23, 2018 9:34 pm

88bluestar wrote:
Sun Sep 23, 2018 6:00 pm
Was thinking of pulling the topend off here soon, and check PV clearance when I install a thinner head gasket. Can this be achieve with a 9 keyway double roller timing set?
If you have the time when doing HG's have the cambers cc'ed . Then you can calculate the CR to use the thinnest gasket to get closest to 9.8 and close up your quench distance the most you can. Dan

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Sun Sep 23, 2018 10:06 pm

Power wise from 9.38 to 9.8, what torque difference is there?

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Re: Large Vortec bowtie, Engine?

Post by groberts101 » Sun Sep 23, 2018 10:48 pm

88bluestar wrote:
Sun Sep 23, 2018 10:06 pm
Power wise from 9.38 to 9.8, what torque difference is there?
I'd guess maybe around 4-6 ft/lbs but remember there's more to an engines powerband than just its peak numbers. More port velocity, crisper throttle/booster response, more average power.

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Re: Large Vortec bowtie, Engine?

Post by barnym17 » Mon Sep 24, 2018 6:01 am

OK this is going to sound bassackwards but add gear to it.Get that thing up where it wants to run, let it ride the chip a little down the straight.The race you need to win is from turn 4 to the flagstand, not hitting peak speed going into the corner.That is wasted speed because if you are hitting the chip right at the corner when you have to let off or brake to set the car its useless. You need the highest average speed (best lap time) not gear it for highest peak speed.

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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Mon Sep 24, 2018 11:15 am

OK , bare with me this might get long winded. First 9.8 is only a static number to be legal the more important thing is what happening in the running motor. Putting a .020 thinner HG on will get you to that legal number . More importantly it will tighten up that .076 quench which is giving you a very lazy flame front . That may be why your motor feels best At 36* adv not at around 32* where the heads is suppose to be designed for.It would be best if you could work the chamber volume ( i am guessing around 67.5)to be able to use a .024- .027 thick HG that would get your quench in the low .040 range. Second the cam is better suited to 10.5 to 11.0 to 1 CR. giving you a late IVC dropping dynamic CR more creating an even slower flame front. Third the intake might not be the best for this application.Dropping lower rpm response even more . Fourth, the head runner is a little big which is not helping that sluggish feeling of the corners.
Each of these items may be with only 5-10 hp but added up its 20-40 hp or more . Each of these things are adding to each other in a snowball effect . Tighten the quench as much as you can to speed the flame front . You will probably need less timing the water temp and oil temp will come down .I could go on more but hopefully you understand that its the whole package that makes a good preforming engine not just one magic part . Most of these thing can be fixed or changes tried for not a lot of money and a little time . Just trying to help .Dan

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Mon Sep 24, 2018 1:00 pm

I’m looking at the least costly decision, only 4 races left in the season and pulling heads after the season.
Running a 7.00 final ratio
Currently running a 780 SMI Holley mech secondary, would a 650 help on the bottom?
Victor jr a better intake option?

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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Mon Sep 24, 2018 2:29 pm

Get your head around a vortec intake for vortex heads.
Try a perf rpm air gap on it. More low end torque.
Or a pro products vortec hurricane
And or move the cam u got and open lash a bit.
These are all low cost.

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