Frankenplenum

[tpepmeie]

Originally Posted by LGAFF

I anticipate 15hp or so...its actually already been proven when they were developing the LT-5

On a 350 cu in. engine? Call me skeptical. I think this really benefits the bigger c.i. engines when the TB becomes a restriction. Not sure you'll see that much on a smaller engine. Interested in what you get, nonetheless.

[LGAFF]

How big was the plenum on that Aurora V8 indy motor.....opinions vary but some say you need a minimum of 1ci of plenum to 1ci of motor....some say 1.5. Really what you are trying to do is come as close to atmosphere as you can...we will see.

[LGAFF]

http://www.can-amcarsltd.com/photo/engine_aurora.jpg

[LGAFF]

http://rejsa.nu/im/_annat/12288-new_...2-bild_006.jpg

[LGAFF]

From Enginelabs....just so one thinks I am full of ****; Todd Berry Custom intake manifold designer

Berry mentions that with custom intakes, the volume of an intake plenum generally matches the displacement of an engine. This means if an engine displaces 500 cubic inches, then the volume inside the plenum is typically going to also have a volume of around 500 cubic inches. Under this type of design, ideally no cylinder is starved for air because the volume inside the plenum is enough to fill all the cylinders simultaneously.
If the volume of the intake plenum is not properly matched and is too small for the application, an engine could develop a stall or sluggish response from an engine at the starting line or after each shift, as combustion events literally draw all the available air from the manifold faster than it can be filled by incoming air. Engines with too small of a plenum may perform well at lower RPM but suffer as RPM increases

[LGAFF]

As I stated, I spoke to two lotus developers on the LT-5, they said best results came with a plenum 1 liter larger than stock. Minimum to start with is 350cu...

[Bearly Flying]

That's quite the set of exhaust headers on the Aurora.

You might have trouble fitting them into your ZR-1.... lol....

Keep up the Good Work Lee,

[LGAFF]

Convertible LT-5



You can see the roof sat right on top of the runner

[XfireZ51]

Originally Posted by LGAFF

How big was the plenum on that Aurora V8 indy motor.....opinions vary but some say you need a minimum of 1ci of plenum to 1ci of motor....some say 1.5. Really what you are trying to do is come as close to atmosphere as you can...we will see.

When doing dyno runs, one thing to look at is the MAP value. This can indicate if there is restriction somewhere ahead of the intake. In the runs I have recorded on my 5.7L, kPa at WOT ~ 97-98 and it doesn't drop hardly at all after peak.
That's pretty close. I also check my KEY ON MAP signal because unless u are at sea level, your MAP won't be at 100kPa anyway.
I'm a bit skeptical like Todd but it's good to have someone like you Lee who'll test it out.

[LGAFF]

Quotes from LT-5 Engineers

"Lee,
As you rightly say splitting the plenum would lend itself more favorably to even cylinder firing events. The net result of doing this on the LT5 plenum would be more torque up to around 2-3k rpm and less everywhere else. As an aside the LT5 is inherently compromised on plenum volume for high rpm operation in its stock form."


"Hello Lee, we found the best results were from adding a liter of volume to the plenum"