Re: Single plane vs. dual plane intake
[Re: mopartruckguy]
#239673
03/02/09 10:32 AM
03/02/09 10:32 AM
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Anonymous
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Anonymous
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We had a very good discussion on this in this thread; https://board.moparts.org/ubbthreads/show...rue#Post5029247From the thread, you will see that I am a dual plane advacate, but the benefits of the dual plane would be less with TBI than with MPI, as you would only have charge volume, not mixture issues to deal with because of mismatched flow.
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Re: Single plane vs. dual plane intake
[Re: Stanton]
#239675
03/02/09 11:04 AM
03/02/09 11:04 AM
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Anonymous
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Anonymous
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Stanton;
Actually, you wind up with more problems with MPI than with TBI because the fuel is put in exactly same on each cylinder (assuming untrimmed). Any difference in airflow not only affects your charge volume, but mixture also, as the fuel is fixed. With TBI the mixture is set before the runners, so it is consistent, leaving you only with charge volume issues.
With a carb, you get both issues, as you get some mixture issues back because of carb signal issues with a single plane.
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Re: Single plane vs. dual plane intake
#239676
03/02/09 11:14 AM
03/02/09 11:14 AM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
With TBI the mixture is set before the runners, so it is consistent, leaving you only with charge volume issues.
That's assuming your intake provides good fuel distribution as well.
If I was to run a TBI, I would definitely go with a dual plane. Carbs perform better on dual planes and dual planes tend to be designed for better fuel distribution and better every day type driving. TBI won't need the strong vacuum signal that a carb likes, but it also depends on your efi controller. If you go port injection, then I think you could go either way. Like booster said, port injection delivers the same amount of fuel to each cylinder, so you really need to get an intake that delivers the same amount of air flow to each cylinder as well to keep your a/f ratios consistant between cylinders, be it single plane or dual plane.
On the mopar 4cyl cars I've toyed with, on the port injected cars I've found even air flow balance to make much more difference than single plane/dual plane type, where single plane type intakes that look like they should have performed awful actually ended up providing the best throttle response and performance.
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Re: Single plane vs. dual plane intake
[Re: DaytonaTurbo]
#239677
03/02/09 11:35 AM
03/02/09 11:35 AM
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Anonymous
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Quote:
Quote:
With TBI the mixture is set before the runners, so it is consistent, leaving you only with charge volume issues.
That's assuming your intake provides good fuel distribution as well.
Perhaps I didn't explain that part very well. Because the fuel and air are mixed before the runners/distribution system, you will have very consistent mixture in a TBI. You may get more/less of that good mixture to each cylinder because of the runners, but it will all be the same mixture. This of course ignors other things like vacuum leaks or fuel drop out. In general, though, the TBI are not very good for performance as they do not atomize all that well, and put a lot of restriction to the airflow.
As Daytona says, it isn't really the single/dual plane that is the issue. It is the airflow balance over the entire rpm range. I like dual planes, because the (can) have much better matching of the runners (and longer runners) for better flow match. Other than that, there is no inherent benefit to a dual plane, as the other thing they do well is put a strong signal on the carb, which doesn't matter. If you do run a dual plane, you are actually better off to cut out the divider to pick up the top end.
I also have seen (one) single plane give suprising performance with a MPI setup. It was a street dominator on my 340. It gave fantastic response and power. Unforturnately, the bad distribution caused it to detonate under boost (turbo), foul some of the plugs, and get 2 mpg lower than the good dual planes.
I guess the net result is that you shouldn't get hung up on dual/single for any other reason than flow balance. You will find some very bad dual planes (Wieand 8007 for one), so just going dual plane is not the answer. I have not found any single plane that is close to the good dual planes.
Techinically, all the very well matched OEM stuff on new cars are single plane.
If you look at the other thead, there are a lot of pics and explanations that might make things clearer.
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Re: Single plane vs. dual plane intake
[Re: bacaruda]
#239679
03/03/09 12:45 AM
03/03/09 12:45 AM
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Anonymous
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Anonymous
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No tests here, but know of a TT440 (feets) with one on it that he is happy with. It has a big advantage as tunnel rams tend to have very well matched runners, so cylinder balance will be good. The downside is that the runners tend to be very large, so you will lose velocity.
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