subscribing.
This is great stuff.
Kory

 

Copying an F-1 style intake is exactly what i'm talking about. Though I think they adjust the height of the injectors (called trumpets) towards or away from the port to change the torque curve. Still, it couldn't be that hard to build.

 

Those "stacks" are called ram tubes. Long=low end,Short- high end TQ&HP.

 

F1 used variable-length "trumpets" (or ram tubes for us Colonials) on the 3L V10s but they were outlawed with the 2.4L V8s now in use. I believe they moved about 50mm (2 in.).

 

http://www.dellorto.it/_Inglese_/tab...sottosezione=2

That is a link to a dellorto web page with a picture and description of the variable length setup used on the Ferrari Enzo, it's at the bottom of the page. Looks like they are getting at least 4 to 5 inches of length variation in that application. Wouldn't be terribly hard to duplicate but it looks like you might have to get creative to fit it above the lifter valley on the LT1 F-body cars.

Here is a description of the Lamborghini variable geometry intake, which is made by Audi:

It is also endowed with dual-length intake manifolds..... This set-up allows for a resilient, flat torque output. To achieve all this the charge efficiency was increased at various speeds by adopting accurate and precise measures for gas dynamics that occur in the inlet and exhaust tracts.

To this end the continuously variable geometry intake manifold guarantees the correct base gas dynamic characteristics at low and high rev ranges. In the low ranges the long runner set-up is used, while in the high ranges the short runner set-up is in use. It's this arrangement that allows for 80% of the 510Nm to be churned out at just 1 500rpm. The opposite scenario is the case when it comes to power outputs occurring at the high rev ranges reaching 7 800rpm.


Pretty intersting technology that lets a motor with a 7800 RPM redline produce 80% of it's torque at 1500 RPM's. Of course it also uses variable intake valve timing and maybe a variable backpressure exhaust ( which the 1000cc sportbikes have used to bulk up the low end with great success since the late 1980's). We have all seen proof from dyno charts on TPI and LT1 intakes that longer runners can kick in a 20% or more increase in torque in the midrange at wide open throttle. One thing I rarely hear people consider is that the torque increase at low throttle openings ( say 1/8 or 1/4 throttle) in the midrange using tuned runners is probably closer to 50%. That's what made the stock TPI's feel like 454's when you blipped the throttle at 2500 RPM's.
Anyhow, whether one used a continuously variable length runner like the Ferrari Enzo or two separate runners, one short and one long like the Lamborghini the results would probably be pretty impressive.

 

The answer really is simple, CUBIC INCHES and a long LSA short duration cam will give you what you want. Low end grunt.

IMO, the reason the above engines were done that way was to help a smaller CI engine make torque in lower rpm ranges. A large bore V8 doesnt have that issue...but if you want to split hairs and re-invent the wheel, you got more time than I have...have fun. GM spent a few $'s on engineering the LT1 intake, overall it does a damn good job. Past that a carb conversion, and past that a sheetmetal....Stock LT1 intakes have gone in the 10's normally aspirated, and low 11's with stock heads....but let us know how it goes.


David

 

Certainly using tuning tricks like variable intakes are a good idea on small engines. The Ferrari Enzo is a 6.0 liter engine and the Lamborghini engine I mentioned is 5 liters. Neither really what most would call small engines but they are cammed up for a lot of topend power (660 hp at 7800 RPM's on the Enzo). The intake and exhaust resonance tuning lets them produce bigtime horsepower yet avoid the crappy lowend and midrange that usually comes with the territory. It's interesting to consider that with a functional variable resonance intake you can install more cam/head and still wind up with strong midrange.

 

Ford used that system with the flaps in '86 an the V6 Escort and every 4.6 has it.
It's 20+ year old tech.

 

So could a system be built for an LT1 to control exhaust flow? Maybe you could use a nitrous window switch to control it? I'd love to be able to overcam my motor and not suffer low-end torque loss.

 

Ford just controls the intake.
Ya control the exhaust with cam timing NOT with flaps that will be burnt up/stuck in no time.
The LT1/4 isn't a 500,000 dollar exotic where if ya owned the 500,000 dollar car ya could afford the up keep.

 

I have an exhaust valve here off a Suzuki GSXR 1000, I bought it off ebay a while back to play with a variable back pressure exhaust on a four stroke motocross bike I was modifying. Never had time to do that but the variable intake I was playing with on the same bike made a huge improvement in low/mid with a small loss of overrev.
The exhaust valves on many of the bikes is a simple butterfly valve, the housing shaft and plate are all stainless steel. I imagine the stuff on the Ferraris and such is similar. The sport bikes are getting around 180 horsepower per liter now ( 1026 horsepower if you had a 350 with the same hp/liter) and obviously aren't cammed for low end. With the exhaust valves they are pretty damned responsive and linear in the low/mid RPM ranges. They don't pick up a great amount of wide open throttle horsepower from the exhaust valves but the part throttle improvement is very impressive.
Why an exhaust valve would necessarily be unreliable and expensive I'm not sure. The ones on the bikes are plenty reliable, at least as reliable as the valvetrain used with big cams in the race motors a lot of people on here build. The electric exhaust cutout valves are pretty reliable and yet they see a good deal of heat.
I think that even with a simple control system like a vacuum solenoid that would open the exhaust valve as manifold vacuum dropped you'd see a good gain. I think the reason more people don't tinker with stuff like this is they are stuck in an intellectual rut and only think in terms of "old school" technology they are familiar with like fuel injection or bigger cams which have been available for 40 years. Don't let other people scare you away from tinkering with new stuff, it can be fun and even occasionally rewarding.

 

"Old School Tech has won many of race and unless ya got the budget of a F-1 team then trying to reinvent the wheel on a SBC is ridiculous.Ya can make them run in the 6's and if ya need more then go to a mountain motor where parts are readily available. THAT'S OLD SCHOOL THINKING.Real smart IMO

 

I dont know of ANY sportbike making 180HP per liter, ZX-14 is the closest, it is 1.3 liters and makes 170 or so HP at the crank. Again a small bore engine needing rpm to make power as most all exotic car engines(small bore, multi valve engine setup)

If the flapper in the exhaust is so good why did all my buddies throw them in the garbage with an aftermarket pipe, picked up upwards of 12 RWHP(with a map) and were MUCH faster? Just like EVERY other sportbike rider? Including myself( Hindle race pipe on my Busa) .


Most guys who raced 4.6 mod motor Mustangs took the flapper valves out of the intake and made more power and went quicker.



David

 

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Ya could have something like these if ya didn't spend all your time and money on diddling with stuff.

The bottom car runs 6.60's with a 4.6 twin turbo.Fastest 4.6 on the planet.
The Teal one has a 4.6 with a Vortec blower.First 4.6 in the 8's
I raced/turned wrenches on both cars for John when I lived out there so the flapper blade thing is understood on a Ford. Got a fair understanding on building race engines also.

 

So at what point does a sheet metal intake start showing gains for a ported heads and big cam combo?

Do you need to go to aftermarket heads or could something like an LE2 heads and cam combo benefit?