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Discussion in 'Generation V Discussions / SRT Coupe, GTS, GTC, AC' started by viper GTS-R, Oct 17, 2013.
You bring up DOHC all the time, get some new material.
Well, I have to..
It is the new material for the viper that would help this car to win..
Pushrod is done for sports cars only SRT and chevy using those... ALL the rest of the world went DOHC ... It means something to me...
And who dominates at the track? SRT and Chevy.
This. Pushrods are better than DOHC engines that can't rev past 8K rpm. C6Z06 revs to 7K rpm with pushrods, all while slinging 7.0L of pistons around. OHC layout is actually an older technology than pushrods, look it up.
+1! Thank you Ralph for being passionate about SRT and Viper, as well as all the engineers who and team members who have also been passionate about Viper.
Not at the drag. Not at the street.
Most of the modern cars going faster are Fords GT500 and 5.0s and have DOHC motors. Chevy and SRT are waaaay behind. Pushrod engine has a hard time to rev up high and keeping the valvetrain stable. It is the engine concept. Yes it will work well for a monster big block making crazy power at the drag but not for cars that live the show room floor of the major dealerships.
With ford you go fast for cheap. If you want to go fast with chevy or dodge to equal or surpass ford you would need to spend a fortune. Not worth it ( I learned the hard way with my ACR that gets spanked by my 5 liter mustang GT with a basic turbo kit running 5.5 psi)
Gt500 > ZL1
5.0 and Boss > SS and Challenger
Ford GT > Corvettes and Vipers
V6 Mustang > V6 Camaro and challenger
Pushrods are good engines but they don't come on top anymore. I have no problems reving my 13 mustang GT to 8k if I wanted to and only couldn't go over that because the auto tranny wouldn't shift the gears if tried to go abover 8000rpm. I commanded the SCT to shift at 7500-7700rpm just for the peace of mind.
As you probably know better than me the LS7 is notorious for valvetrain issues and head geometry related problems. It drop valves, etc. etc.. It is a pushrod to the max for the street and in my opinion a glass engine. I personally prefer the smaller Ls3 and ls9 for durability than the Ls7 even though they spin less.
As Technology takes both engine designs to the max it will always have DOHC coming on TOP. The pushrod engine needs to be a lot bigger just to try to keep up with the DOHC in a race
Perhaps I am in a different crowd, but I never really thought of the Viper as a drag racer. I always thought it was purely a track monster. Thats why I wanted it, personally. Only so fast you can get with a RWD car off the line at stock.
LS7 may rev but making sure you still have all exhaust valves in place afterwards is a part of routine maintenance.
Pushrod motor cars benefit from an overall lower engine center of gravity vs OHC motor cars.
Also, they are typically lighter depending upon the materials used in their production.
Lol. The Ford GT stock for stock would get slapped down on the track by a Z07 trim Z06 or a ZR1 or any new Viper. It's a wonderful car, but it hasn't been updated since it was discontinued, and Corvette and Viper have gone a long way since then.
You need to get out more. LS7's had quality control issues on a minority of engines but the good ones give no trouble, and the hand built race ones have been dyno'd for 300 hours under hard out track simulations - try that in your supercharged heat soaked Ford. It's not DOHC that gives Ford an edge at some racing it is BOOST! They lack the bottom end of the LS let alone a Viper V10 and the top end is countered by higher CG and huge bulk. Horses for courses but the push rod is not dead. Did you know the NA LT1 makes 460hp and can exceed 40mpg at cruise speeds (not over a tank but at steady speed) - don't tell me pushrods are inefficient when they pack more cubic capacity into a smaller lower space, have better bottom end torque and are more fuel efficient at cruise.
BTW V8Supercars down under now run quad cam Nissan and Mercedes V8's against the old school Ford and GM 5 liter engines, Guess what? Mercs are slowest and pushrods are winning everything (except for 1 race where Nissan pulled off a one off win). Despite all makes having the same regulation power (about 630hp), the quad cammed engines can't compete on pace or fuel consumption. Push rods are not dead.
The viper is a track monster. I love mine, don't get me wrong. Chassis, brakes, suspension, looks, etc.. are great on the viper.... But the tranny and engine are not on top anymore.
Tires re the simple part of the game IMO. You just choose the right ones and change them for road racing or dragracing or even better keeping a second set of rims ready for your favorite type of race. I cut as low as 1.55 60' with my viper and the car is a rocket of the line on drag radials. Unfortunately, the factory PIRELLIS won't help your 13 in any type of race I'm afraid..
Seemed to do quite well around Laguna, with better tires it would have left the ZR1 in the dust.
Agree but, I'd rather sacrifice a little bit on that center of gravity to gain on a better engine overall.
The DOHC engine is extremelly light today as well. Yes, a little heavier than the pushrod of the same size. But you gain in all other areas in including HP/ TRQ expecially in high RPM where it matters the most when racing.
Yeah of course. It's a 2005 car that was ahead of its time and it is still amazing for todays standards. It is not what I would buy if I wanted to go around the track because of the supercharger heat soaking. But at the street and at the drag or roll racing it will MURDER a Corvette or a viper with very little mods ( maybe a $100 supercharger pulley?)
The Ford GT has crazy TOP End Power and one of the most reliable engines that was proven time after time to take well over 1k HP of supercharger or twin turbo. No Viper or Corvette engine out of the factory never achieved anything close to that reliably speaking with only 5.4L of displacement. LOL @ 7 liters or 8 liters pushrods...
Viper and vette have come a long way with their Chassis, suspension, aero, weight reduction, tires, brakes, looks, etc... But not on the engine and tranny itself... Sorry. That to me is frustrating because I wanted to see them growing in those areas too.
"LS7's had quality control issues on a minority of engines"
That is not true. There were A LOT of blown CHEVY LS7 Engines. I know at least 3 guys that blew theirs racing. One was drag racing, the other one was road racing and the last one was doing a couple pulls at the highway against another car. The first two dropped valves and god knows what happened with the third one since that one caught on fire after it broke the
motor. Call up any engine Chevy engine builder in the States and I am sure he/she will help to clarify that and even state other failures that the LS7 was prone to. That was one of the
main reasons I choose the viper instead of the Z06 in 2010.
"It's not DOHC that gives Ford an edge at some racing it is BOOST! They lack the bottom end of the LS let alone a Viper V10 "
NOT true again. Boost is just the icing on the cake for an already superior engine. Your boosting 2 intake valves and 2 exhaust valves instead of only 2 of the pushrod engine. That makes the gains even higher. That is one of the reasons why the bigger motor ZL1 camaro gets embarassed at the drag track by smaller displacement gt500s and even N/A 5 liters.
You talk about DOHC engines like they are honda civic engines. These engines that I am talking about all have 5 or more liters of displacement and over 400 horse.
I drove a z06 and one time driving my viper I almost got embarassed by a 2011 5 liter on roll racing with boltons and he had no boost or major mods. The dohcs of today have great bottom end and top end well, I won't discuss that anymore.
"Did you know the NA LT1 makes 460hp and can exceed 40mpg"
I am not impressed by the horsepower nor how far I can go with one tank tank of gas on that ugly car.
People shouldn't buy SPORTS cars for fuel economy. I want something that will go fast and will consume fuel accordingly. If you want more great MPG just buy a hybrid. My wife did and she is happy. I on the other hand bought a triple fuel pump system with huge lines and 1000ccs injectors for my mustang and want that thing to DRINK and to perform.
Your beloved 460HP transformers vette is running 12.3 stock in the quarter mile bone stock in a HEAVIER CAR tha BEFORE. Do you call that a great achievement by GM? I call that fail because a 5.0 mustang can run faster than 11.8 bone stock in the quarter mile and costs 28K instead of +60K
"don't tell me pushrods are inefficient when they pack more cubic capacity into a smaller lower space, have better bottom end torque and are more fuel efficient at cruise."
WOW... So pushrod is the perfect engine for everything them, hum? So why Formula Indy and Formula one are not using them since they are the holy grail of the racing and technology?Because only the DOHC design allows those engines to spin to 22.000 rpm and achieve over 900 HP if they want out of a 2.5L engine. No pushrod ever did that and never will, so yeah for that type of racing( (that stands on top of all others) they are dead. Please, don't tell me that pushrod is more efficient than what I just mention because is NOT.
It doesn't matter anymore if you can pack N/A pushrod power in smaller space since you cannot extract the ponies out of it like you can do with OHC. No, you can't throw a nasty cam ona pushrod engine out of the factory and pass emissions. It is not going to happen, not even in your wildest dreams.
I don't care about BTW because it is slow compared to F1 and Indy where a pushrod if allowed to race would always finish LAST.
Lastly, This MPG thing is such a lame excuse OMG, OK I will sacrifice some miles per gallon to have the BEST under my muscle or sports car hood!
Viper, ZR1 both great cars but they could be better. They need to change their mentality first or I am afraid the viper can die.... I don't want that. I want the car to evolve in this competitive sports car era that we live in...
Your thinking about being green and fast is dinosaur cave man stuff. It's not about what you can afford but being ****ing responsible given your children might see the end of oil, if not theirs will, don't be so selfish. Emissions and mpg do matter today. You sound like a young person.
In racing OHC comes into its own at rpms way above what any OEM wants to warranty on a big engine. At rpms a big street engine can turn and be warrantied - push rods can hold their own. Each has their pros and cons.
I don't give a fig about your flying OHC Fords, they're great engines, but there's plenty of push rod engines that will beat them. A guy up the road has a 1078hp sub 400 ci small block Ford push rod engine that turns 11,000rpm in his 6 second rail NA on carbs and gas. Try that in your modular 4V.
V10, have you considered that what you are looking for in a car is different than what the Viper was designed to be? You clearly are willing to accept a heavier engine with a higher CG, which is fine for drag racing and street racing (which I grew out of a long time ago), but are detrimental at the road courses. If SRT wanted to rule the streets, they also would've gone with all wheel drive. Forced induction also works well for short bursts of acceleration but gets heat soaked at the hands of a skilled driver on the road course. So for you, a big heavy AWD DOHC forced induction car is the ticket. That's not at all what the Viper is about.
SRT's mission in designing the Viper was clearly stated by the team - road course dominance. A lightweight, normally aspirated big-cube pushrod V10 is the ticket. Lap times don't lie. Mission accomplished.
Regarding your suggestion that the LS7 engine is unreliable, that is patently false. They in fact are quite the opposite. All of Corvettes are extremely reliable on the track, as are Vipers. I just returned from driving Corvettes at Spring Mountain. Guess what? They've NEVER blown a Corvette engine. Never. And they've been running Z06s, ZR1s and Grand Sports for at least 8 years, a large fleet of them in the Ron Fellows school.
OHC only has one benefit over OHV. Valvetrain stability at high rpm. That is the ONLY benefit. That being said, can we at least agree that any OHC engine that doesn't at least rev to 8K rpm - is just a waste of the OHC's only benefit.
OHV has a few benefits over the OHC.
-Much smaller packaging/dimensions, given the same displacement.
-Less cost to manufacture
-Lighter weight, given the same displacement.
-Lower Center of Gravity
So, I still stand by my beliefs that the pushrods are a better alternative to sub-8000 rpm engine builds. If a DOHC can't rev, it isn't worth much.
I've also owned and modified both the OHC mod-motor Mustangs, and the LSX OHV engines. The LSX engines kick the crap out of any Ford engine, mod for mod. I'm not talking about boosted applications, as that doesn't have to do much with the valvetrain design, just a factor of pushing more psi.
Example about Formula 1 cars is cute. How about NHRA record setting pushrod 500ci V8 engines that make estimated 8,500-10,000hp? That is real man's power.
New LT1 OHV is no longer simple nor light. No doubt OHV is cheaper to manufacture but it is not as nearly as efficient as OHC, especially DOHC using multiple valves ran off separate camshafts. The difficulty of stabilizing valve trains at higher RPMs in OHV is very well documented through LS7 failures. Emission restrictions are dealt considerably easier with OHC than with OHV, these are facts.
Please drop the LS7 failures stuff, that gets overplayed by the anti-LSX crowd. They built thousands of those cars, and the failures are related to using crappy quality valveguides. We've been spinning LS1 engines up to 7,000 rpm since 1999, when we first started getting aftermarket valvesprings and Ti retainers that could keep up. That was 7 years before the LS7 came out. I had a 434ci LS6 back in 2001 that revved to 6,800 rpm and made 535 rwhp. That was a lot for 2001.
I also owned a 3-valve Mustang GT that had the piston contact the cylinder head, so should I assume all mod motors are junk? Nope, that would be ignorant. But, my LS7's never failed, so they are perfect right? Nope, again. Isolated cases, which is normal on a mass-produced mechanical device.
I am not sure what 'problem' people are trying to solve here by suggesting OHC versus OHV in the Vette and Viper engines?
My old 32-Valve 281 Mustang Cobra engine was monstrously large compared to a Vette engine. Vette engine not efficient? With DI, Cylinder Deactivation, and gas mileage in the 20s?
Let's just go to Pneumatic Valves...
Deja Vu...Seems like all Gen V threads turn into a turd fest...
Yeah, what was this thread about again? Oh yeah...
Anything mechanical fails sooner or later. Manufacturing defect is one thing, the conditions under which it affects the engine is another. LS7 problems are not isolated, they are massive. Only the users who typically experience these problems are seldom, since not too many Z06 owners take their cars to drag strips or tracks. Assuming GM is telling the truth, any LS7 prior to 2011 "correction" IF raced, has a great potential to dropping the valves (at higher RPMs).
You mistake fuel efficiency with THERMAL efficiency of ICE.