Well I saw on a top gear episode that the a lotus used a quad cam from a camry...has anyone put a quad cam engine into our fieros? The reason I ask this is I would like to eventually put a high red line engine in to get a more exotic feel ( so far i plan for a northstar )...but has anyone even considered a quad cam? It seems more imports are quad cams but you can't line them up to our trannies...Hoping to have a job monday ( crosses fingers ) so just kinda fishing around to other swaps etc before I jump in on one.
------------------ Cliff's 610th Positive Feedback Giver. #12 NYFOC Member In recent times, the custom aftermarket car/automobile roadwheel has become a status symbol. These wheels are often incorrectly referred to as "rims". The term "rim" is incorrect because the rim is only the outer portion of a wheel (where the tire is mounted )
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08:48 PM
PFF
System Bot
Carcenomy Member
Posts: 1109 From: Invercargill, New Zealand Registered: Jan 2009
GM aren't dorks who use terms like 'Quad Cam' to describe their engines, they use the accurate term 'DOHC'. Quad Cam might sound more awesome, but really what that means is it's a DOHC engine with two banks. Therefore... YES. There's been plenty of quadcam conversions - the 3.4 TDC and Northstar immediately spring to mind.
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09:24 PM
Hockaday Member
Posts: 2165 From: Clifton Park, New York, The States. Registered: Sep 2009
QOHC and DOHC are different..or should be...a QOHC engine is like two inline DOHC engines put together. Two cams for the intake two cams for the exhaust. 4 in total not two.
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09:28 PM
Carcenomy Member
Posts: 1109 From: Invercargill, New Zealand Registered: Jan 2009
Originally posted by Carcenomy: GM aren't dorks who use terms like 'Quad Cam' to describe their engines, they use the accurate term 'DOHC'. Quad Cam might sound more awesome, but really what that means is it's a DOHC engine with two banks. Therefore... YES. There's been plenty of quadcam conversions - the 3.4 TDC and Northstar immediately spring to mind.
Actually I believe they may have used such a term to describe the LT5 in the early 90s ZR-1, which was designed by Lotus.
Though, what Lotus has a V6 in it? The V8 Esprit was DOHC, I believe, but certainly no Camry engine. And the Elise and Exige are both 4 cylinder cars. The 4 cyl in the Exige is a Toyota/Yamaha engine, but would only have 2 cams sitting above the valves. It is DOHC, but certainly doesn't have 4 cams.
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11:22 PM
Hockaday Member
Posts: 2165 From: Clifton Park, New York, The States. Registered: Sep 2009
For the non-tech people who are reading this, it may be interesting to give some basic information on engine design. So what makes the Northstar engine so very special ? First of all it is of the Dual Overhead Cam (DOHC) design. That means that camshafts are not located centrally, as in a classic engine. Instead the camshafts are mounted above the valves. This means that there is no longer need for pushrods or rocker arms, eliminating a lot of internal friction and power loss. "Hey", I hear you say. "You are constantly talking about camshafts (plural ), why's that ?". You are right, "normal" engines only have one camshaft, which is centrally located in the V-block. The Northstar (and some other American and European V8's) has multiple camshafts. Each cylinder head has two camshafts, mounted above the valves. The reason for having more than one camshaft per cylinder head, is the amount of valves that are involved in the Northstar. Again, "normal" engines only have two valves per cylinder (one intake and one exhaust). In order to allow better engine breathing and better cylinder filling, the Northstar has two intake valves and two exhaust valves per cylinder, totaling 32 valves. Having only one camshaft per head, would result in this camshaft operating on 16 valves. Not only would this require a special valve layout, but it would also result in an enormous loss due to unnecessary friction. With a DOHC design, one camshaft operates the intake valves, the other one the exhaust valves. So as a matter of fact, the Northstar has four camshafts, compared to one as in a classic V8 (like the Cadillac 4.9 liter). Another reason why the Northstar is so special, is that is made completely out of aluminum. This makes the engine considerably lighter than one in cast iron. The Northstar engine weighs about 230 kg, about the same as the 4.9, despite the additional valves, camshafts and related chain-drive components. When you make a car lighter, you have less dead mass to drag with you, and you get an overall more performant machine (the so-called horsepower to weight ratio). The Northstar engine has a host of other improvements over the 4.9, amongst them a special modulating intake manifold and a special kind of distributor. A normal engine uses a device which contains a rotor or cam to close contact points and create a spark. This always implies using moving parts, subject to wear. The Northstar Engine does not have any moving parts in its iginition system. Magnetic sensors are positioned at the crankshaft and camshafts. Those sensors are triggered by notches in the crankshaft and camshaft. These generate an ON-OFF pulse wave, similar to the open-closed position of classic breaker-points. This wave is interpreted by the ignition module, containing 4 ignition coils (1 coil per 2 opposed cylinders). As the wave signal enters the ignition module, a high energy voltage is generated in the appropriate coil, resulting in two simultaneous sparks in the opposing cylinders. Since one cylinder is at its exhaust stroke, this spark will have no effect. This system is called waste spark ignition
So my question is..why not call it a QOHC or a TDC...now yes I should have realised i suppose since it has 32 valves that it had four cams...but wouldn't it make more sence to call it one of the former names?
[This message has been edited by Hockaday (edited 08-21-2010).]
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11:29 PM
wftb Member
Posts: 3692 From: kincardine,ontario,canada Registered: Jun 2005
Originally posted by Hockaday: QOHC and DOHC are different..or should be...a QOHC engine is like two inline DOHC engines put together. Two cams for the intake two cams for the exhaust. 4 in total not two.
The SOHC or DOHC acronyms apply to any number of rows of cylinders on an engine. You apply it to a single cylinder and expand for all of them, because having a V engine with one side operated by pushrods and another with an OHC, makes no sense. Even the W16 in the Veyron is still a DOHC.
there are new gm v6 engines that are all aluminum 4 cam motors.some people call them ecotec v 6's but i dont know what displacement they are .
They are the new High Feature V6 engines from GM. The most common one is the 3.6L version. I believe there's also 2.8, 3.2, and they were working on a V12 which had been cancelled.
They are the new High Feature V6 engines from GM. The most common one is the 3.6L version. I believe there's also 2.8, 3.2, and they were working on a V12 which had been cancelled.
Aren't the alumminum head dohc 3.6 liter v6's u guys r talkin about in g6's?
Originally posted by Hockaday: So my question is..why not call it a QOHC or a TDC...now yes I should have realised i suppose since it has 32 valves that it had four cams...but wouldn't it make more sence to call it one of the former names?
Just because each cylinder has 4 valves, doesn't mean that it has 4 cams. A SOHC engine could have 4 valves per cylinder as well (like the 1.6L engine in the Mini Cooper). And some DOHC engines have 5 valves per cylinder (Ferraris). And some Italian cars use "Quattrovalviole" to descirbe 4 valves per cylinder.
The important bit isn't how many cams there are. It's what the total volume of air being flown through the valves is, and how they are timed.
Originally posted by HausFiero: Aren't the alumminum head dohc 3.6 liter v6's u guys r talkin about in g6's?
Torrent, G6 GXP, Camaro, CTS, Aura. They're in lots of GM cars. The LY7 is the FWD version in the Aura/G6/etc… I've been scoping their prices on eBay, as I'll probably be doing one in my 85 GT after I finish the LS4 swap in my 87 GT.
Just because each cylinder has 4 valves, doesn't mean that it has 4 cams. A SOHC engine could have 4 valves per cylinder as well (like the 1.6L engine in the Mini Cooper). And some DOHC engines have 5 valves per cylinder (Ferraris). And some Italian cars use "Quattrovalviole" to descirbe 4 valves per cylinder.
The important bit isn't how many cams there are. It's what the total volume of air being flown through the valves is, and how they are timed.
Yeah, technically more cams would be worse if it didn't flow as much air because more cams means more weight. But usually dual cams do the job in flowing more air in to produce more power, and a higher redline I believe.
As for the 3.6L high feature engines, I would LOVE to see people start putting these into fieros!!! (I believe it would be the engine the modern day fiero would have too)
Torrent, G6 GXP, Camaro, CTS, Aura. They're in lots of GM cars. The LY7 is the FWD version in the Aura/G6/etc… I've been scoping their prices on eBay, as I'll probably be doing one in my 85 GT after I finish the LS4 swap in my 87 GT.
Originally posted by HausFiero: Yeah, technically more cams would be worse if it didn't flow as much air because more cams means more weight. But usually dual cams do the job in flowing more air in to produce more power, and a higher redline I believe.
Having an overhead cam, as opposed to a pushrod/rocker system, will allow an increased redline, due to less points of failure. The lifters, pushrods, and rockers don't exist, and therefore won't receive any stress. Instead, the cams open the valve directly. Due to the angles of the valves, a DOHC accomplishes this much more efficiently. SOHC on the other hand, does still need rockers for a 4 valve engine, as the cam sits in between the valves, which lean in opposite directions. F1 engines these days use pneumatics to keep the valves closed, rather than springs, which further increases the rev limit. But they also have very short strokes. And Renault is working on an electro-hydraulic system, which would totally eliminate the camshafts, and provide infinitely variable valve timing, controlled by the engine management.
