Wonder why single plane intakes run, start and idle better than dual plane intakes on a big block?

G72Zed

Veteran Member
Sep 8, 2015
4,241
Canada
So the best dual plane was equal to a basic single plane?

Sorry, you picked up 3 thousandths. With a dual plane. Not convinced.

You can have 5 different dual planes, and each one could be "the best" one on 5 different engine combo's....

Sometimes the engines actual "performance" is in the heads/cam & trapped charge, think "positive harmonic" .

Sometimes the intake does nothing but hold the carb up.....

Also, why would you run a 4 hole tapered carb spacer on a single plane? Did you purposefully choke it to prove a point?

Your kidding right ????
 

1980RS

Veteran Member
Jun 17, 2006
6,559
MN
So the best dual plane was equal to a basic single plane?

Sorry, you picked up 3 thousandths. With a dual plane. Not convinced.
It just showed how equal both intakes were. Most said I would pick up 3 tenths with the RPM over the Single plane and others said 3 tenths the other way. Ask the guy with the 383 single plane intake AFR headed SBC Camaro what happened the day we raced when I ran my 358 with the Air Gap. Numbers don't lie. His 11.43 does not beat an 11.33 that I had with that dual plane intake. Next year I will test 2 more dual plane intakes on my L-29 engine. One with the divider cut down 1" and the other with the divider cut all the way down. My base ET to start with is a [email protected] after that's all done I will put my Team-G single plane intake on for a test, bet there won't be much difference.
 

G72Zed

Veteran Member
Sep 8, 2015
4,241
Canada
I actually wasn't kidding or joking about running a 4 hole tapered spacer on a single plane. I don't see any reason to do it.

Ah, OK, so you are being serious then Rustbucket350 ? thought sure you were joking.

FWIW, here's a dyno sheet of just 1 example out the last few dozen that have been involved in that benefited of some sort of 4 hole merged spacer, this was a 383 sbc mild pump street build. This used a 1/2 inch 4 hole on top of a 1" 4 hole tapered.

The others are race builds, and I won't share the results or pic's, but let's just say "they" $ee the rea$oning behind using one.


383 - 305 heads 4 hole merged 1.5 inch.jpg
 

1980RS

Veteran Member
Jun 17, 2006
6,559
MN
Ah, OK, so you are being serious then Rustbucket350 ? thought sure you were joking.

FWIW, here's a dyno sheet of just 1 example out the last few dozen that have been involved in that benefited of some sort of 4 hole merged spacer, this was a 383 sbc mild pump street build. This used a 1/2 inch 4 hole on top of a 1" 4 hole tapered.

The others are race builds, and I won't share the results or pic's, but let's just say "they" $ee the rea$oning behind using one.


View attachment 151457
If you can bolt on a spacer of any kind and pick up a tenth or a MPH than that's the cheapest performance you will get for your buck. Spacers are just another tuning tool that at times can make a crap intake look good. Just like carburetor tuning, there's a reason I can take an 1850 Holley 600 vs and put my engine in the mid 11s' with it. I still have people calling BS on that one but my Son was there and saw what I did and was laughing his arse off when he saw what I ran with that 600 on that day. Thanks for that graph with the spacer G72Zed
 

G72Zed

Veteran Member
Sep 8, 2015
4,241
Canada
If you can bolt on a spacer of any kind and pick up a tenth or a MPH than that's the cheapest performance you will get for your buck. Spacers are just another tuning tool that at times can make a crap intake look good. Just like carburetor tuning, there's a reason I can take an 1850 Holley 600 vs and put my engine in the mid 11s' with it. I still have people calling BS on that one but my Son was there and saw what I did and was laughing his arse off when he saw what I ran with that 600 on that day. Thanks for that graph with the spacer G72Zed

X2^^ Yes, you are absolutely right on the money 1980RS.

I use spacers (inserts) of all kinds of shapes and sizes just to see what the additional runner length and data says or indicates what the engine's intake tract wants or needs more or less of.....every one is different.

Then, the next thing is to see what the "lap counter" or ET says, it may or may not agree with the results, after all, unless it's an EMC effort, you don't race dyno's.

I was on the dyno one day tuning a new build, pump gas mild BBM, 470 cube. I made 590hp with my smallest 650CFM Holley, then on a 358 SBC LOL.

The engine can only use/move so much air, quality trumps quantity in many cases, but everybody likes big numbers as it sounds good LOL.
 




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