05-16-2018, 07:31 PM | #29 | |
Drives: 1969 Mustang MaCh1 Join Date: Nov 2015
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1969 Pro-Touring MaCh 1 - CHP 427w 10.8 comp - 3140 lbs. - 460 rwhp / 490 rwtqT56 Magnum || 14" 6 piston front / 13" 4 piston rear Wilwood brakes || Hydraulic clutch || 9" Detroit Locker || TCP Coilovers || Forgeline Wheels 18x10 275/35 front, 19x12 325/30 rear |
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05-17-2018, 10:36 AM | #30 | |
Drives: 1SS, A8, MRC, NPP, Blade Spoiler Join Date: Jun 2010
Location: MD
Posts: 1,485
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Also, the technology to get the fuel efficiency and emission are employed on BOTH designs, so weight was added to both. In fact, when you deploy variable valve timing to the DOHC design, it adds more weight than when deployed on an OHV engine because you need four hydraulic actuators rather than just one. Case in point: Coyote vs. LS3. LS3 was a bit lighter and smaller. Coyote vs. LT1, LT1 was a bit smaller but a bit heavier due to DI. New Gen Coyote vs. LT1, the LT1 is a bit smaller and lighter because the new Coyote added Dual injection. But the main thing to remember is that the LT1 has 6.2 Liters of displacement where the Coyote is 5.0. More displacement is more torque under the curve. If you shrunk an LT1 to 5.0 Liters, it would be significantly smaller and lighter than the Coyote. |
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05-17-2018, 11:26 AM | #31 | |
I used to be Dragoneye...
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But that's the thing, isn't it? Two different answers to the same performance question...and the regulation that's driving it all: emissions. |
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05-17-2018, 12:32 PM | #32 |
Drives: 1SS, A8, MRC, NPP, Blade Spoiler Join Date: Jun 2010
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Yes, exactly. If you started at the beginning of this thread, you know that the simplified equation for HP in and ICE is HP=RPMs * Torque(at that RPM). So, you can increase HP by increasing RPM's or by increasing torque. So, if you increase RPM's you get more peak power, but it is only increased at the top of the RPM range. If you increase torque, you increase HP everywhere on the RPM range.
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05-17-2018, 12:47 PM | #33 | |
I used to be Dragoneye...
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05-17-2018, 01:09 PM | #34 | |||
corner barstool sitter
Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012
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On pushrods . . . they are subject to lateral deflection along their length, so you can't open valves operated through them as fast as you can with more direct-acting mechanisms, especially since the greater mass of bigger valves + pushrods + lifters then requires the valve springs to be stiffer to control it all at any given rpm. Quote:
You can comfortably fit about 3.65 total inches of valve diameter in a 4" bore OHV (2.05" I + 1.60" E). But you can fit two 37mm intakes and two 32mm exhausts into a 3.70" bore. The difference in total intake and exhaust curtain areas at any given amount of lift is significant, to say the least. Quote:
As mentioned before, it does come down to where (and how) you want to be operating. Some prefer more torque down low (and this admittedly suits automatic transmissions better), while others would rather work with higher revs when they're "playing around" and aren't as concerned about torque @1500 - 2500 rpm because they aren't using it all when they're down there anyway. FWIW, I don't hate pushrod engines. Norm
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05-17-2018, 02:04 PM | #35 | ||||
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Look at it this way. An ICE is nothing but an air pump. You can make a little pump and turn if faster, or a smaller pump and turn it slower and get the same exact air flow. But the one running slower won't need the extra benefit of having four valve, because it never spins fast enough for one to cause a limitation. Quote:
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05-17-2018, 05:54 PM | #36 | |
corner barstool sitter
Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012
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Side note, that tiny bore is one thing in particular I don't care for about the modular-design Ford motors. I feel that a 93-ish mm bore (3.66") is really better suited to 8-cylinder displacements between about 4.0L up to 4.2L. Side note #2, there actually have been a couple of pushrod 4-valve designs for the older-gen SBC. The LS would have been a better starting point Norm
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05-17-2018, 08:40 PM | #37 | |
Drives: 2018 SS 1LE Join Date: Apr 2017
Location: North Jersey
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05-18-2018, 10:11 AM | #38 | |||
Drives: 1SS, A8, MRC, NPP, Blade Spoiler Join Date: Jun 2010
Location: MD
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Truth be told, what's really holding back the pushrod design in terms of being able to raise the RPM's of peak HP is the emission standards (IIRC cold start emission is tough here). You can buy Chevy's heads and cam for the LT1 and get 535HP right out of the box. Or you can just buy the LT376/535 crate engine right from Chevy. 535 N/A HP with all that low end torque would make a nice replacement in an SS 1LE if that person's engine blew up. That would be a blast at the track! |
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05-18-2018, 05:50 PM | #39 |
corner barstool sitter
Drives: 08 Mustang GT, 19 WRX Join Date: Jul 2012
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It's always nice when somebody goes and builds something - whatever it might be, not just engines - the way you'd prefer to see it built.
Norm
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