Intake spacers

[kenthompson]

Would there be any interest in delrin spacers for the plenum rather than phenolic?

[Paul Workman]

Originally Posted by kenthompson

Would there be any interest in delrin spacers for the plenum rather than phenolic?

Forgive my ignorance as I'm new to the LT5. But, are you referring to the (Lingenfelter) heat barriers that isolate the intake from engine heat? If so, I guess the remaining question is how well does durilin work, and what do you want for them?

P.

[kenthompson]

Yep, same thing, different material.

I'm 100% sure delrin is the material to use. But I'm not convinced wood is either.

KT

One of the big problems with the spacers is .... not everybody can run them. Some people had hood interference issues.

The spacers also help control heat loosely. You have to remember the whole motor is a heat sink and when it starts to heat up it will radiate the heat. The plenum will still get hot.

The one big problem is they require multiple sets of gaskets. Unless you secure one side of the sapcers to either the plenum or injector housing, you run the risk of not only buying 2 gaskets, but the possibility of 4.

[kenthompson]

Originally Posted by Jeffvette

One of the big problems with the spacers is .... not everybody can run them. Some people had hood interference issues.

The spacers also help control heat loosely. You have to remember the whole motor is a heat sink and when it starts to heat up it will radiate the heat. The plenum will still get hot.

The one big problem is they require multiple sets of gaskets. Unless you secure one side of the sapcers to either the plenum or injector housing, you run the risk of not only buying 2 gaskets, but the possibility of 4.

Kinda wondered about the heat sink issue.

The gasket issue was one I had thought about. Wouldn't make economic sense to use four 35 dollar gaskets. That why I was thinking about o-rings for seals. I need to look at the stock gaskets I have to see if there's enough material around the ports to machine grooves in the delrin to fit an oring.

Of course, that all changes again when we go to 36 MM ports!

[tpepmeie]

Adding length to the runners will also change the tuned RPM slightly, from the stock 6800 rpm to something more around 6600 (w/ 0.5" increase). The stock intake is tuned by the second harmonic to 6800. Adding significant taper to the runners can act to shorten the effective length somewhat.

Just theory, of course. I don't build engines

Todd

[Paul Workman]

Originally Posted by Jeffvette

The spacers also help control heat loosely. You have to remember the whole motor is a heat sink and when it starts to heat up it will radiate the heat. The plenum will still get hot.

I hear ya, Jeff. The barriers are only effective to the degree they reduce the flow of engine heat into the plenum by way of direct conduction. Radiation from the engine will not be affected. After a hot soak in a parking lot on a summer day, the plenum will be very close to that of the engine, regardless of heat barriers. Only after the engine runs for a few minutes - the faster the better - will the plenum cool (somewhat) and air density increase (theoretically).

I'm intrigued by the plastic plenums used on the LSx engines... The entire plenum is a very low conductor of heat, and has a relatively low 'specific heat' value (read: it does not retain much heat & will cool rapidly). And, the inside of the runners are glass smooth...not a bad thing! So, it's fun to think about what value such a plenum might offer to the LT5 as well...

Just makin' conversation here...

P.