Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 15, 2021 18:03:33 GMT -5
this is all hypothetical but im just doin the math and all that jazz to build a killer ls motor out of factory parts for as cheap as possible- because why not
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Hotfoot674
Heat Winner
If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 15, 2021 18:06:27 GMT -5
i have this awesome book called "auto math handbook", im no mathmatecian ( i can barely spell) but with a calculator and that book i can do some serious damage
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Hotfoot674
Heat Winner
If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 15, 2021 18:13:50 GMT -5
ok so heres some formulas
carb size for street use is as follows: cfm of carb = [ (rpm x displacement)/ 3456] x 0.85
racing carb is as follows cfm of carb = [ (rpm x displacement)/ 3456] x 1.10
lets say we have a sbc 350 that we expect to rev to 5000 rpms max: cfm of carb = [ (5000 x 350)/ 3456] x 0.85 this comes out to 430 cfm this is why you DONT need a holley 750 on your average derby engine
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LS engines
Feb 15, 2021 20:38:19 GMT -5
via mobile
Post by Luke Wells on Feb 15, 2021 20:38:19 GMT -5
ok so heres some formulas carb size for street use is as follows: cfm of carb = [ (rpm x displacement)/ 3456] x 0.85 racing carb is as follows cfm of carb = [ (rpm x displacement)/ 3456] x 1.10 lets say we have a sbc 350 that we expect to rev to 5000 rpms max: cfm of carb = [ (5000 x 350)/ 3456] x 0.85 this comes out to 430 cfm this is why you DONT need a holley 750 on your average derby engine Got some problems here... 1st you have written street use, then in your last sentence it says derby engine. Also, wouldn't this formula vary wildly with the build (or lack of) for an engine?
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Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 16, 2021 9:24:50 GMT -5
No this is just cfm that your engine uses
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Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 20, 2021 17:05:24 GMT -5
6.0 and 5.3 wont rev past about 6.5 grand because of their long stroke, I did the math and the piston speed was to high, but have lotsa torque because of said long stroke. 4.8 will rev but doesnt have torque. (I did the math for a hypothetical 8000 rpm screamer made out of only stock ls parts that was a 328 cid ,4.8 crank in a 6.0 block and it should have a little more torque due to displacement.) I would chose a 5.3 just because of their aviliability and if it has an ally block- SELL IT. 6.0 is too rare-ish in my area so I prolly would use it in a street car before destroyin it in a derby car so with your research which puts out the best torque stock for because we aren't here for horsepower in my builds I got for more torque since I'm not here to run no quater mile race track. I've been told 5.3 is the best one to go with bur never looked in it my self yet. Not ready to get into LS builds yet but thinking of soon. There's no replacement for displacement... 6.0 almost definately makes the best torque stock but also burns the most fuel so makes the most heat as i said 6.0 is too rare in my area so ive never derbied one
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DTOM101
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"IT WOULD TAKE A COIL SPRING ON THE CARB TO KEEP MY FOOT OFF THE FLOOR"
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Post by DTOM101 on Feb 21, 2021 0:07:22 GMT -5
For horsepower 6.0. For derby application it’s all about the heat. What makes the LS favorable are the heads . New guys want to build a motor an get head work. Problem is they choose to work the wrong valves. If it’s a derby motor i don’t care what size the intake side is. I want the biggest exhaust valve to let the heat gtfo. This is common for the guys building the conventional sbc. So stock form on the LS it has the bigger exhaust valve factory. The mains are another favorable aspect. They pull a lot more vacuum than the older sbc as well. That being said if it’s a derby engine give me the 265 or 283 over the bigger cube sbc. An with the LS I would buy a 4.8 . All about the heat . As for formulas go. If a man gets that deep into it. There are many that need to coincide with others an need to jive or it’s one step forward an two backwards. The cam pistons an static compression. It’s one of those things you might think you know until you realize you don’t know squat. I choose to be the shade tree type. I haven’t seen him on in a long time but there is a bunch of good info on these LS engines in the thread that Joker and others covered an he says what to address an save you a bunch of time not messing with things that don’t need addressed. I’ll also say if you nose a car with an LS without a mid plate or protectors there’s a good chance . The starter will lay on the ground
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Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 21, 2021 7:43:20 GMT -5
Yes the displacement deal is true, that's why no one except for non motor swap guys run big block chevrolets.
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Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 21, 2021 7:46:15 GMT -5
guy goes to the machine shop, "can you bore the exhaust valve to the biggest size humanly possible?"
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Hotfoot674
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If you're headers aren't cherry red by the end of the night then you didn't try/hit hard enough,
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Post by Hotfoot674 on Feb 21, 2021 7:50:12 GMT -5
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DTOM101
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"IT WOULD TAKE A COIL SPRING ON THE CARB TO KEEP MY FOOT OFF THE FLOOR"
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Post by DTOM101 on Feb 21, 2021 10:46:28 GMT -5
Here we go...... Most guys will take a 1.94 intake 1.5 exhaust head to machine shop for a derby build. Punch the intake out bigger. I would take that same head. Leave intake valve alone an get a 1.6 exhaust valve put into it. Again all about the heat . I know guys that run big blocks without fail in the derby world. On alcohol. Caddy Ford an Chrysler . See the manufacturer has already done the engineering for the most part. An the camshaft is going to play a huge role in determining any of those formulas . Static compression is overlooked as well. Not big deal on a dome or dish piston but a flat top it most certainly is. In general if you run a small bore engine you want a cam to open an close as fast as possible . You do not want a high lift cam . An definitely don’t want a big intake valve on a small bore engine . An compression is the cheapest HP in my opinion . Take a 454 with 8:1 an a 350 with 12:1 naturally aspirated which has more power? Idc what heads . An you can run 14:1 on a derby engine no problem just buy a good starter.
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Post by derbyguy02 on Mar 5, 2021 17:47:40 GMT -5
Guys need alittle of opinion I got a chance to get a 2001 6.0 or a 2003 4.8 both runs and I trying to narrow down with one I should go with both are similar in price
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Post by smashford on Mar 6, 2021 2:57:47 GMT -5
The 6.0
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4379x
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Post by 4379x on Feb 7, 2022 23:18:34 GMT -5
Sorry guys I hate to do this year because I see there’s 110 pages of information, without going through every page what would you recommend fuel injected like holly terminator or carb swap? If carb swap with a Holley 500 or Rochester 2G carb is sufficient, any advice would be helpful thanks .
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owen11x
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Post by owen11x on Feb 8, 2022 6:49:13 GMT -5
Sorry guys I hate to do this year because I see there’s 110 pages of information, without going through every page what would you recommend fuel injected like holly terminator or carb swap? If carb swap with a Holley 500 or Rochester 2G carb is sufficient, any advice would be helpful thanks . As a guy that hates electrical and likes to to keep things as simple as possible id go with the carb 2g less that can go wrong.is always better
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