# someone edumacate me
**URL:** https://forums.speedlife.net/t/someone-edumacate-me/42273
**Category:** NYSpeed Automotive
**Created:** [January 22, 2008, 5:20pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273 "2008-01-22T17:20:13Z")
**Posts on this page:** 12
**Page:** 2
### Author:  [@mike125k](https://forums.speedlife.net/u/mike125k)
#### Post date: [January 23, 2008, 10:55am UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/21 "2008-01-23T10:55:20Z")
> [@Oroc](#):
>
> The early 90’s ZR1 Corvettes with the LT5 were an DOHC motor 32 valve and it rocked!! one of the fastest motors ever produced. Why GM didnt stick with that technology IDK, maybe cost?
>
> C5 Z06s are rated at 405hp, the Zr1s were rated at 375-405hp depending on year and anyone who knows the old zr1’s knows they were underrated. I saw a stock dyno of one that put down 430rwhp NA untouched.
Yes, it was cost why they stopped. The motors were all aluminum and built by Mercury Marine and were very expensive. They were awesome motors though.
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### Author:  [@articzap](https://forums.speedlife.net/u/articzap)
#### Post date: [January 23, 2008, 10:57am UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/22 "2008-01-23T10:57:34Z")
Weren’t the LT5’s engineered by Lotus or something? I can’t remember.
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### Author:  [@mike125k](https://forums.speedlife.net/u/mike125k)
#### Post date: [January 23, 2008, 11:23am UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/23 "2008-01-23T11:23:09Z")
> [@articzap](#):
>
> Weren’t the LT5’s engineered by Lotus or something? I can’t remember.
I believe the heads were designed by Lotus.
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### Author:  [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)
#### Post date: [January 23, 2008, 4:54pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/24 "2008-01-23T16:54:42Z")
lotus designed… mercury marine built
there are alot of incorrect assumptions in this thread.
dohc or sohc or ohv doesnt matter as far as power output and power delivery are concerned. all that matters are headflow, port shape and port size and how they interact with the manifolds and camshaft. you can get the same result with either style valvetrain. ive been in small block chevy powered cars that didnt come alive till 4k and screamed out till 9k. I own a 16v 4 cyl vehicle that doesnt want to rev past 5500 but makes decent torque for a 1.6L.
the advantage of DOHC 4v/cyl heads are that you dont have to open the valve very far or have a gigantic port (and the low velocity that comes along with it) to get good head flow because you have basically two ports and two valves for the intake and another two for the exhaust. disadvantage is size and complexity.
advantage of OHV 2v/cyl heads are simplicity and the overall engine package is small. to get a good flowing head you have to make the port large and open the valve alot which can make the engine soggy in the low revs if the port shape and volume arent paid close attention to. disadvantage is that there is alot of metal from the cam lobe to the valve tip so materials must be kept light and valve springs stiff or you cant turn high revs. all those pushrods and rocker arms and lifters add up when it comes to fast valve movement. many times the factory designs a OHV cyl head for ease of production and low cost vs proper port placement and design. so you get small ports that make lots of velocity and high torque and the stigma that pushrod v8’s (and v10’s ;)) are only for low end and not revs.
when you design a OHV head for flow and not low cost you get something that looks like the LS7 head… i dont know of too many DOHC heads flowing 360cfm on the intake from the factory.
Brian
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### Author:  [@TrueBlue](https://forums.speedlife.net/u/TrueBlue)
#### Post date: [January 23, 2008, 5:04pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/25 "2008-01-23T17:04:51Z")
> [@OfficerK](#):
>
> mmmm I heart the 4.6 mod motor…
>
> kind of sweet to see it side by side :tup:
> [@ubengineering](#):
>
> i never really realized the size difference fuck
Yeah, I love that picture. Big difference - especially when you compare block cross sections.
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### Author:  [@bpipe95](https://forums.speedlife.net/u/bpipe95)
#### Post date: [January 23, 2008, 5:17pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/26 "2008-01-23T17:17:03Z")
> [@Violator](#):
>
> Ford GT is DOHC.
>
> Pushrod motors are cheaper to build too and they work well if the RPM’s are kept low.
> l
What do you consider low RPM’s
8k 9k
I mean pushrod motors were doing 8k stock back in the 60’s
They can work just fine in higher RPM applications, But in all honesty they sure as shit don’t need to spin fast to make power.
GM has made so many advances in the pushrod design and efficacy there is no need to change as of now.
look at the trucks for example, last I checked there is not another manufacture that makes a motor. be it a OHV or OHC that gets better MPG than the GM GenIII motors.
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### Author:  [@HAiRymONkEe](https://forums.speedlife.net/u/HAiRymONkEe)
#### Post date: [January 23, 2008, 5:17pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/27 "2008-01-23T17:17:08Z")
> [@TrueBlue](#):
>
> Indeed. The 4.6L is actually smaller in displacement than a 302 (5.0L) but look at the size a DOHC head adds:
word , the 4.6 is 281 cubic inches.
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### Author:  [@reliant\_turbo](https://forums.speedlife.net/u/reliant_turbo)
#### Post date: [January 23, 2008, 6:57pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/28 "2008-01-23T18:57:44Z")
> [@bpipe95](#):
>
> What do you consider low RPM’s
>
> 8k 9k
>
> I mean pushrod motors were doing 8k stock back in the 60’s
>
> They can work just fine in higher RPM applications, But in all honesty they sure as shit don’t need to spin fast to make power.
stock 318 chrysler can sing at 7k all day long. 🙂
Brian
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### Author:  [@TrueBlue](https://forums.speedlife.net/u/TrueBlue)
#### Post date: [January 23, 2008, 7:19pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/29 "2008-01-23T19:19:37Z")
G-code 302’s (Boss 302) and the DZ code 302 (Z/28) both were spinning 7,500 rpm on the streets, and were hitting 9,000 rpm for hours at a time during Trans-Am races in 1969.
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### Author:  [@Violator](https://forums.speedlife.net/u/Violator)
#### Post date: [January 23, 2008, 10:20pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/30 "2008-01-23T22:20:46Z")
> [@bpipe95](#):
>
> What do you consider low RPM’s
>
> 8k 9k
>
> I mean pushrod motors were doing 8k stock back in the 60’s
>
> They can work just fine in higher RPM applications, But in all honesty they sure as shit don’t need to spin fast to make power.
>
> GM has made so many advances in the pushrod design and efficacy there is no need to change as of now.
>
> look at the trucks for example, last I checked there is not another manufacture that makes a motor. be it a OHV or OHC that gets better MPG than the GM GenIII motors.
6500K reliable daily production car.
I wish people would stop splitting hairs. Who cares what it “could” do. We are talking about simple daily use and not race motor that gets rebuilt every race.
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### Author:  [@bpipe95](https://forums.speedlife.net/u/bpipe95)
#### Post date: [January 23, 2008, 10:31pm UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/31 "2008-01-23T22:31:48Z")
they were the stock production motors, the 302 in the z28 not race motors that get rebuilt.
also the ls1 is just fine spinning past 7k with a cam swap.
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### Author:  [@HYBOOST](https://forums.speedlife.net/u/HYBOOST)
#### Post date: [January 24, 2008, 9:19am UTC](https://forums.speedlife.net/t/someone-edumacate-me/42273/32 "2008-01-24T09:19:40Z")
> [@ubengineering](#):
>
> i never really realized the size difference fuck
I remember going to a cruise nite with my brother in law a few years ago. He came running over to me because he saw this “giant motor” in a new Mustang. He thought it was some special large displacement transplant. I told him it wasnt & it was less displacement than his sons 5.0. Took him an hour & talking to the owner to finally believe me.
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