[steve25]

Many factors come into play to answer that exh to intake ratio question, like Cam specs, compression ratio, but two main things are the motors fast piston speed due to its stroke and if your racing and running open headers with a well set up tuned collector lenght, and especially if there merge collectors making a lot of vacuum at overlap.

Many times there’s no substitute to find out what the motor wants but for pure empirical testing back to back at the race track on the same day.

[ta man]

Once I get on a decent track..I will be testing 2 carbs and at least 3 different spacers..possibly a few more.

[Steve C.]

Throttle body and plenum area.

Switching from a carburetor to fuel injection with a four hole throttle body and and direct port injectors. On the dyno with the carb it liked a 2" open spacer the best. Any reason it would change with the swap?

https://www.yellowbullet.com/threads...-area.2627101/

( Information provided in this post does not represent any endorsement and it is not based on personal experience and is offered for general interest only. Not Pontiac specific with a Torker II intake ! )


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[djustice]

I can confirm the 4-hole spacer whistle-fix. I have an edelbrock performer , and with an open edelbrock heat insulator gasket 1/4" thick there was a loud whistle under part throttle, i bougth a 3/16" (i think) 4 hole spacer and that solved all the noise problems.

[Tom Vaught]

Even the very old NASH 4 BBL manifolds liked a spacer above the plenum.
And some added Plenum Volume on engines larger than the 366 CID by enlarging
the Bottom of the intake plenum by dropping the floor of the plenum.

Most "hid" that modification in the old days on their 455 type engines and had "cover plates"
over the runners so you could not see the plenum mods.

Tom V.

[Tom Vaught]

Carb metered and made more power with the spacer because the fuel charge was BOTH "more even" to all of the cylinders but also because the proper amount of air was able to to the intake runner requesting it in the time allowed.

EFI systems like large plenum volumes to the runners.

Look at a Marcella manifold or a Hogan manifold. LARGE PLENUM AREAS

Tom V.

[Steve C.]

With the custom fabricated intake style like those from Hogan that large plenum allows individual runners to have the same cross section, length and all with a straight shot into the heads. Much different that a Torker II intake that has only four of it's runner lengths the same. And the Torker II has only two of it's runners with the same amount volume (cc).


With direct port fuel injection it has been stated one of the advantages of having a dry plenum and runners is that they can twist and turn more sharply to equalize airflow between cylinders without disrupting the air/fuel mixture. Does that apply with the Torker II intake ?


Edit: The statement here about the Hogan intake style was an assumption on my part. Tom, correct me if it does not apply.

[Steve C.]

"EFI throttle-bodies are different than carburetors because they don't need a "signal" to get the air/fuel charge moving. And in a port EFI system, the intake is dry; there's no fuel through the throttle-body or intake runners to fall out of suspension. But there's still the issue of total system volume versus engine airflow requirements, so in that sense spacers could still prove to be of benefit on EFI setups, although less so than in a traditional carbureted application."

Source:

How Carburetor Spacers Affect Performance

https://www.motortrend.com/how-to/pi...t-performance/


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