If/When you go to siamesed Intakes?

[tpepmeie]

Originally Posted by alnukem

It got me wondering, when & what parameters to use this method. I do comprehend the concept of drawing from 2 ports. I am sure RPM & Engine Size dictates use, just curious when. And, if cylinder porting would be different. I doubt I would ever do, just curious how it is used. Thanks, Tim

650 rwhp and the inj housings are still divided on mine, and only 35mm ports. The plenum runners are the figure eight style like Bob posted. Definitely not the welded mono style.

Different ways to skin the cat, bigger isn't always necessary. LPE got good power for the times with the mono plenum runners. However, if you've seen pics of their inj housings they were not siamesed either. Either "D" port on the secondary, or "double D" ports, from what I've seen.

Todd

[Schrade]

Originally Posted by batchman

I would think the separation between runners would become important with respect to cam timing of the two valves - do they open in unison (stock cam) or is there a difference in cam timing?

- Jeff the curious, who will wind up with exactly one chance to get it right and still meet class rules....

This is a good question - the reason I asked if anyone has done flow test on the bench OR IN A LAB.

Airflow through the tubes - just like water flow - has dynamics - AEROdynamics. The column of air has LAMINAR flow - momentum, going through the tubes.

Introduction of turbulence can create eddies. But, DEPENDING on where it is in the intake mechanics, it can be good (think of GM's VORTEC induction), OR, it can be 'not beneficial'.

And I say 'not beneficial', as opposed to BAD, conditionally; with some reservation here.

Making a bigger hole WILL allow more air, which without question, will benefit an engine with the hammer on the floor.

But what about mid-range? And low end?

Best example that I can think of, is L98's intake manifold. Flow characteristics of L98 intake are 'templated' on flow characteristics of an LB9. L98 loses out top end, NOT because of the VOLUME THAT THE INTAKE ALLOWS, BUT BECAUSE OF FLOW DYNAMICS.

Another example came from another forum board - discussion of the 'Foil', on the throttle body. After thinking on it - how it would stop air from 'bouncing' (turbulence), off of the OEM TB divider (of the 2 TB openings), made me think further on it's benefits. Throw a rock in a pond, and watch the waves 'bounce', AND COME BACKWARD EVEN, WHEN THE WAVES HIT THE "No Fishing" sign. Then I posted that in a forced air induction system, it should REALLY be beneficial, to reduce the 'bounce'. User 'Joe', whom some of you probably know, after lurking about, posted up 'Bingo', on the forced air induction/ benefits.

A true MONOrunner plenum has dynamics already considered.

So I'm asking again here; has anyone done flow dynamics tests, of any sort, on OEM vs 'siamese-d' tubes? Or even, Before and After TQ/HP numbers???

[Kevin]

i'd like to see down into the IH of Mark H's 385. with that dropped plenum I'd like to see what LPE did there

[LGAFF]

Really what I would like to do it

Divide the plenum in two to create a helmholtz resonator
Create a air horn/veolicty stack entry into each set of runners

[RHanselman]

Originally Posted by LGAFF

The Siamese port actually started with Gulstrand and then TPIS who both made a siamesed TPI runner....TPIS version was more like the one Locobob and I did.....

Lee, I have to recover some brain cells lost at BG this past year however I ran into a guy that told me about the first true Siamese and it wasn't for Gulstrand. I believe it was for LPE or Jeal. I'll do some research and get back with you. You know, it might have been Graham telling me?? Guess I'll have to give him a call... Billy K comes to mind but again, those brain cells are dead...

Cheers,

[Kevin]

i remember the sheet metal intake that billy k made for his car.

[LGAFF]

I am talking about the TPI stiff Ron, TPIS/Gulstrand did siamese with TPI runners...which is were I think the term was first used......you are correct on the LT-5....I was just speaking to the way it was done on those...some combined with no center ridge, some did not

[RHanselman]

Originally Posted by LGAFF

I am talking about the TPI stiff Ron, TPIS/Gulstrand did siamese with TPI runners...which is were I think the term was first used......you are correct on the LT-5....I was just speaking to the way it was done on those...some combined with no center ridge, some did not

Copy, your talking L98 then. I wasn't sure because of the 1990's having TPI on the side

[RHanselman]

Originally Posted by Kevin

i remember the sheet metal intake that billy k made for his car.

I thought this thing was cool looking. You could see the top flex when he revved her up... Probably needed a little more volume and some stiffeners.

[LGAFF]

Actaully Ron, the first Siamese was the snakeskinner car......from sports car illustrated:

"The secondary throttles have been removed, so the engine is always drawing air through both runners. The intake runners have been siamesed along part of their length by cutting out the wall separating them. The cams are stock......."

This car ran 11.83@123 .....launching at 1600 RPM

This is from May 1992 mag...the 1989 Snakeskinner 1