Aftermarket Product ReviewProvide questions and answers about aftermarket parts for the Third Generation F-Body.
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anyone ever seen these or know anything about them? 4 valve sbc heads, damn thats power on a whole new level. why dont more people talk about it? there must be a reason why i havent seen these before...
__________________ "Jenna"
88 T-top IROC-Z
L98, T-56
Too much to list...
thats the advantage...low lift numbers. but a proper ported 15-18 degree head should flow enough to match a 4v head. hell even 23 degree heads are flowin like mad
---What do you mean it wasn't a small block----
"The highly anticipated ZR1 Corvette was introduced in 1990 and became known as "The King of the Hill". It was to be the fastest ever Corvette with an approximate maximum speed of 180 mph, doing 0-60 in 4.2 seconds making it the quickest accelerating production car in the world. Everything in the car, including driveability, performance and the need to meet federal emission and mileage rules, is computer controlled. The ZR1 was the most expensive GM car ever made, but compared to other supercars of the time, it was comparatively cheap.?"
"The thing that makes the ZR1 special is its engine, the LT5, designed by Lotus. The incredibly complex V8 all alloy engine was based on the standard Corvette engine configuration but was improved by the addition of four overhead camshafts operating four valves per cylinder, giving a grand total of 32 valves. The LT5 engine is boosted by its air intake system that can either take oxygen from a single narrow throttle valve or from a wide mouth intake depending on the pressure applied to the accelerator. The engines were manufactured and assembled by Mercury Marine."
Just because it uses the same bore spacing doesn't mean it's a small block, despite what a journalist says. Count how many parts are interchangeable between an LT5 and an SBC.
By that logic then the Gen III and IV sbc's arent small blocks either which would make it what? poor planning on the part of GM? Just curious about your logic.
Those are at least arguably progressions of the original design. The Gen III engines especially are quite similar to the classic SBC.
The LT5 was an entirely original design totally unlike anything else. The block is actually multiple castings, with a separate cylinder case and crankcase.
Cool drawing, and fast! But in the diagram it looks like the cyl. are sleeved, not a seperate component i.e. V.W. But thats the best explaination I could ask for!
But that doesn't answer the question if the heads could work, different bolt pattern, water/oil ports, crank to head measurements (for cam drive), and I can't see how a conventional head design could compete with the flow of four valves?! If you only have 2 valves in a sbc side by side and do the math, you will find more valve surface area can be obtained when having multiple valves. But I guess CFM is CFM as far as flow from the head?
CFM is CFM, no matter how many valves you use. Yes, 4 valve heads would have more flow in "midlift" or with smaller cams. So basically, they would be great for a street oriented motor, but at such a high cost, decent standard type heads(23 degree) and forced induction would still make more power for less $. For race, mid lift doesn't really matter, so you might as well be running 18/14/12 degree heads that can out-flow those four valve heads. - Also, you have odd-ball valve train(the entire top half of the motor is freak), and the addition power it costs to move all the extra components.
Yes, they have been around for years, I belive Barry Grant even toy'd around with some. - The bottom line is that other than the "coolness" factor, they're not worth it....
A lot of factory cars are multi-valve now, my Lincoln has a 5.4 32 valve V8 producing around 300hp stock, and it's brother the Expidition has the same motor with 24 valves. When is GM going to catch on? Yes, Shagwell you CAN get more cfm out of some highly modified (2 valve) heads, but if the same modifications were made on 4 valve heads wouldn't the flow be higher?
And as far as costing horsepower to dive cams, etc. couldn't the same be said for superchargers? If the horsepower gain exceeds the power loss from modification isn't it worth it in the end?
As far as multi valve/cam set ups have been around for a while. My engineering associate and his machinist friend had a Mercury Inteceptor in the 1950's that was twin turbo/twin cam/32 valve motor that was completely designed and built by themselves --- BEFORE CAD! ---
Simply stating every cut had to be made by hand, one slip the project is ruined, with the new generation comming up you know some people can harly function without a computer-aided something. You think you can find one of those cool drawings of the Bugatti motors?
A lot of factory cars are multi-valve now, my Lincoln has a 5.4 32 valve V8 producing around 300hp stock, and it's brother the Expidition has the same motor with 24 valves. When is GM going to catch on? Yes, Shagwell you CAN get more cfm out of some highly modified (2 valve) heads, but if the same modifications were made on 4 valve heads wouldn't the flow be higher?
And as far as costing horsepower to dive cams, etc. couldn't the same be said for superchargers? If the horsepower gain exceeds the power loss from modification isn't it worth it in the end?
As far as multi valve/cam set ups have been around for a while. My engineering associate and his machinist friend had a Mercury Inteceptor in the 1950's that was twin turbo/twin cam/32 valve motor that was completely designed and built by themselves --- BEFORE CAD! ---
well, GM was making lots of 4 vlave per cyl. motors for a long time. some of the popular ones that come to mind from 1988 and up are 2.3 dohc , 2.4 dohc, 3.4 dohc, northstar (and it's brother what ever the v6 olds one was)and the list goes on and on today the s/t trucks are the ecotec motors as well. one trend is torque seems to suffer. although a mid rpm range and up hp street car may look good on paper it's not what you feel when you test drive one off the lot or when you pull a boat.
Not enough V8's, though...and it's funny I'm not as fond of Fords as GM,but I have three! Excursion, Navigator, F150...
I JUST CAN'T SEEM TO GET MY THREE KIDS AND PREGNANT WIFE INTO THE FIREBIRD!
^^ Not to mention all the extra rotational weight and friction associated with multiple cams/overhead cam motors... more moving parts = more friction and more weight, not to mention more things to break and go wrong.
just my 2 cents: its an sbc simply because it was made for gm, specifically "chevrolet" corvette. the engine was just another engine in my mind, but was an advanced feat for its time in the domestic market. yeah, parts can't bolt up to other sbc's, but that's a part of making engines evolve. every manufacturer has plenty of engine parts that you can not swap around.
as for power...can't complain with any engine you have money to sink into. you can tune a 4 cyl. to have 800 hp as well as tuning a v8 to make the same amount. you can rebuild an old sbc and drop tt's on it make immense amounts of power. and you can do it for less than one of these engines go for, if you can find one for sale. the last one i saw for sale was a few years ago on the internet and the guy wanted $10k for it. screw that!
using the 3 kids and pregnant wife as an excuse to buy ford products isn't acceptable either! just kidding! buy a suburban!
A lot of factory cars are multi-valve now, my Lincoln has a 5.4 32 valve V8 producing around 300hp stock, and it's brother the Expidition has the same motor with 24 valves. When is GM going to catch on? Yes, Shagwell you CAN get more cfm out of some highly modified (2 valve) heads, but if the same modifications were made on 4 valve heads wouldn't the flow be higher?
And as far as costing horsepower to dive cams, etc. couldn't the same be said for superchargers? If the horsepower gain exceeds the power loss from modification isn't it worth it in the end?
As far as multi valve/cam set ups have been around for a while. My engineering associate and his machinist friend had a Mercury Inteceptor in the 1950's that was twin turbo/twin cam/32 valve motor that was completely designed and built by themselves --- BEFORE CAD! ---
I think it is funny how GM dumped the LT5 and went with the LS1/LS6/LS7 with "old fashion 2 ohv" technology. Yet those engines spank the Ford 32V?
There are a LOT of advantages to ohv technology. If not, why are some Japanese motorcycle manufacturers switching to OHV technology on some of their V-twins? Especially, when some of their older models were SOHC or DOHC?
How about RELIABILITY and DURABILITY? How about EXPENSE/COST to manufacture? How about a GOOD port design on an OHV engine can produce as much power as a poor port design on a DOHC 4V/cyl head?
Just because an engine has DOHC & 4 Valves/cylinder doesn't make it better. I know lots of Ford guys and many would much rather have the old 2 valve Windsor engine than their new OHC 4valve engine.
PS: The price of those Arao heads have jumped up almost 50% from just a year or two ago. And, good luck finding headers that will fit an F-body using the Stahl/Hooker pattern.
just my 2 cents: its an sbc simply because it was made for gm, specifically "chevrolet" corvette. the engine was just another engine in my mind, but was an advanced feat for its time in the domestic market. yeah, parts can't bolt up to other sbc's, but that's a part of making engines evolve. every manufacturer has plenty of engine parts that you can not swap around.
as for power...can't complain with any engine you have money to sink into. you can tune a 4 cyl. to have 800 hp as well as tuning a v8 to make the same amount. you can rebuild an old sbc and drop tt's on it make immense amounts of power. and you can do it for less than one of these engines go for, if you can find one for sale. the last one i saw for sale was a few years ago on the internet and the guy wanted $10k for it. screw that!
using the 3 kids and pregnant wife as an excuse to buy ford products isn't acceptable either! just kidding! buy a suburban!
The only reason I bought the Excursion is beacause It's a 2000 w/72k mi. and fully loaded for $8,000, the wife drove the Lincoln we(she) didn't like the Caddy
The F150 is for work and it has 172k (who would want to kill another Chevy?) and it get the crap beat out of it! Trying to get rid of the Lincoln so I'll have 3 cars/no payments
I think it is funny how GM dumped the LT5 and went with the LS1/LS6/LS7 with "old fashion 2 ohv" technology. Yet those engines spank the Ford 32V?
There are a LOT of advantages to ohv technology. If not, why are some Japanese motorcycle manufacturers switching to OHV technology on some of their V-twins? Especially, when some of their older models were SOHC or DOHC?
How about RELIABILITY and DURABILITY? How about EXPENSE/COST to manufacture? How about a GOOD port design on an OHV engine can produce as much power as a poor port design on a DOHC 4V/cyl head?
Just because an engine has DOHC & 4 Valves/cylinder doesn't make it better. I know lots of Ford guys and many would much rather have the old 2 valve Windsor engine than their new OHC 4valve engine.
I have both, the Triton 289ci and the Intech 330ci, and let me tell ya' the Intech will spin the tires in a 7,000lb truck with traction control! If your comparing a "poor design" 4 valve head to a "good design" 2 valve head, that's like saying a well designed 4cyl will out power a poorly designed 8cyl! If you compare apples to apples and max out the valve size in both the 4valve and 2valve and perform all the same procedures, the 4valve head SHOULD flow better!
I'm still partial to GM as I am as loyal as the next guy, just trying to state facts....
Not to mention i"m sick of reading "What can I do to my 3gen for more performance?"
Yet the new 500hp svo Stang (s/c 5.4L 32 valve) outperforms the GTO and the Charger hands down!
GM PLEASE HELP!!!
What's competing with the Lightning (same motor as svo 'stang) or the new Dodge p/u (Hemi)?
Did you see how the STS twin-turbo 'vette put down 550+ HP at the wheels with just SEVEN (7) POUNDS OF BOOST? What does the GT500 Mustang put down at the wheels?
What does the GT500 Mustang put down at the wheels?
Early dyno runs on new Shelbys show about 440-450 rwhp. But there's discussion that the PCM is programmed not to achieve full power until x number of starts and/or x,000 miles...... No one knows for sure yet.
....Im not impressed by the GT500...
That's probably because it's too new and not well know (yet) how receptive this engine is to simple mods. This might change your mind:
Yet the new 500hp svo Stang (s/c 5.4L 32 valve) outperforms the GTO and the Charger hands down!
GM PLEASE HELP!!!
What's competing with the Lightning (same motor as svo 'stang) or the new Dodge p/u (Hemi)?
How about the LS7 Vette? And it only took Ford 10 years to finally get ONE of their DOHC 4V engines to finally perform.
The bottom line, DOCH 4V technology is NOT cost effective for the performance when you see what GM has done with it's "old fashioned" ohv 2 valve technology (and as mentioned above, GM has had MANY DOHC 4V engines).
This is why Ford is headed for bankruptcy and GM will survive.
What does the GT500 Mustang put down at the wheels?
Early dyno runs on new Shelbys show about 440-450 rwhp. But there's discussion that the PCM is programmed not to achieve full power until x number of starts and/or x,000 miles...... No one knows for sure yet.
....Im not impressed by the GT500...
That's probably because it's too new and not well know (yet) how receptive this engine is to simple mods. This might change your mind:
Consider one will be in my garage in 12-18 months.....
Hmmm...
Personally, I will never own a Ford. I would rather drop a LSX into my 91 RS and boost the hell out of it before I buy a stinkin Ford.
I will watch those vids soon. Cant right now though (In MS 2273B class... Going for my MCSA!)
If I had to buy a new car, I would get the 06 GTO and throw some form of forced induction on it. I would hate to have all of my GM buddies CLOWN ME for buying a Mustang.
I am a LOYAL GM fan and I will continue to be until the day I DIE!
If everyone want apples for apples, then why are we comparing a supercharged 4-valve(cobra/gt500) to a na 2 valve(LSX)?
I'm loyal to GM, but unless they get the market more realistic, I'd buy a Ford too. What did the 4th gen Camaro SS's go for loaded? $30,000+, how bout a loaded Mustang GT(same model year)? $25,000 - So now I have $5k+ to put into it just to have what GM was getting stock, and for $5k the 4.6 (even the 2valve)can be built to walk all-over LS motors.
I've got a buddy running an 02 GT 2v 4.6 - The car lays down 330hp and 308ftlbs to the wheels, naturally aspirated and has a torque "curve" that looks like a table top. I've watched him spank LSX cars that just layed over 500 to the wheels on a dyno day. Pull out in the street and drive away because his powerband is so broad. He's running 12.30 on 17" street tires, fully interior, a/c, full power, daily driver(his only wheels), and his pain in the azz TKO 500 is coming out because you can't shift it w/o clutching and lifting of the go pedal. - I've yet to see a stock 4-valve do that na or sc, but now we're back to apples vs oranges (stock vs moded)
Cfm is mostly limited through bore size and port size. Yes, some applications could/do make more power with multi-valve heads. In most situtions a decent 2 valve head can make the same power, although a good 4-valve head might make more mid-range and possibly slightly better response. But for all-out power, X-cfm is X-cfm, not matter how many valves you use to get it.
- As I and others already stated, with multi-valve heads you loose some power due to the extra valve train. Think of how much pressure it takes to open you valve springs, now double that for the extra valve, and add in the extra lifters/rockers(or followers for OHC) and you're gonna loose some power.
extra valves aren't the end-all to anything, so why would a manufacturer(GM) need to "update" to this technology in their performance vehicles if theer is no real proven gain. - also as other have stated, GM does have/use this technology, they even have a supercharged northstar available in the XLR.
To each his own. I am not brand specific. I even like the new Challenger... but will eventually get the Shelby GT500....
I would rather drop a LSX into my 91 RS and boost the hell out of it before I buy a stinkin Ford.
What do you be "before". I've done both with a TT 305.... and my Cobra. "The best of both worlds" I call it. Why limit yourself to one brand? They don't always produce the best product every time... As I've always said, open both your eyes with an unbiased viewpoint and don't use "brandnames" as a limiting factor that may bias your opinion. Just my opinion though.
Did you see how the STS twin-turbo 'vette put down 550+ HP at the wheels with just SEVEN (7) POUNDS OF BOOST? What does the GT500 Mustang put down at the wheels?
What about a GTO with one of those kits? Hmmm...
Im not impressed by the GT500...
For the same price as a fully loaded 1/2 ton pick-up? ($40k)
How about the LS7 Vette? And it only took Ford 10 years to finally get ONE of their DOHC 4V engines to finally perform.
The bottom line, DOCH 4V technology is NOT cost effective for the performance when you see what GM has done with it's "old fashioned" ohv 2 valve technology (and as mentioned above, GM has had MANY DOHC 4V engines).
This is why Ford is headed for bankruptcy and GM will survive.
Willie - What you runnin' in the quarter? And are u stock?
Fastest car I ever messed with was an '86 'Stang w/355 (350 chev .10 over) 350 tranny, 250hp button...11.88 on motor, 10.33 on juice...the "Moustang" was .......you guessed it --CHEVY ORANGE!--
Last edited by firstfirebird; 09-20-2006 at 01:11 AM.
