Magnum intake

w0158981 · Post by **w0158981** » Thu Oct 01, 2009 9:06 am

The magnum intake manifold stock add's power on a base neon, but without the butterflies i've read it actually it can cause a loss of power, Now i'm assuming that a port and polished intake without the butterflies would provide a severely worse loss in power? correct?

hul kogan · Post by **hul kogan** » Thu Oct 01, 2009 9:21 am

Not necessarily. I'd imagine it might be slightly worse, but I don't see the loss being too drastically different than a stock manifold without butterflies. All you are doing is improving flow a bit.

w0158981 · Post by **w0158981** » Thu Oct 01, 2009 10:24 am

see thats what confuses me, if i'm improving flow, how am i losing power? i understand with the exhaust a certain ammount of back pressure is needed unless you are pushing enough power out that a straight pipe is beneficial. But as for intake wise wouldn't more flow be better?

r/tguy02 · Post by **r/tguy02** » Thu Oct 01, 2009 10:55 am

the loss is only in a specific rpm range, not a loss across the board. if they stay open all the time you will see a drop in power from ~3,500-5,000rpm only, there are dyno graphs showing this.

JeffM · Post by **JeffM** » Thu Oct 01, 2009 11:10 am

r/tguy02 wrote:the loss is only in a specific rpm range, not a loss across the board. if they stay open all the time you will see a drop in power from ~3,500-5,000rpm only, there are dyno graphs showing this.

That's because at that range the butterflies are suppose to be closed, causing more vacuum, and allowing the correct amount of air. If you don't have the butterflies you are just supplying extra air that is not particularly needed.

I would imagine a P&P would be good for the rest of the RPM range but still giving you that loss at 3500-5000.

Post by **occasional demons** » Thu Oct 01, 2009 12:14 pm

It's more about the velocity, or speed of the air flow, not how much is there. If the runner diameter is too large the air slows down, making it harder to pull into the cylinder. The butterflies help keep the speed in the sweet spot, to get the air into the cylinders. This is why the Indy suck balls for N/A, the runners are too large. With boost the velocity is made up for, because the air is being pushed past the valve, instead of relying on the pressure drop created as the piston drops in the bore. So with a bone stock engine a little porting prolly won't affect it too much, but majorly hogged out might cause a loss of low RPM torque. From the IM shootout on the other .org, it seems the Magnum IM can't be prted too much, due to the thinner walls.

ZeroChad · Post by **ZeroChad** » Thu Oct 01, 2009 2:10 pm

I love posting this graph. As long as you have the shaft for the butterflies, making new ones is pretty easy.

anomalous0 wrote:when you get the secondaries hooked up your life will be much better.
Bottom end might still not be as good as stock, but that might just be because I have a magnum cam if you swapped one in with the magnum head that might be part of it. Your top end will feel like a whole new animal. No more choking at 5000 RPM
The magnum cam needs the magnum intake manifold to reach it's true potential, and the magnum intake manifold works best with at least a magnum cam, as the stock cam doesn't flow as much air or have as much duration, and so contributes to the choking problem. Together, they make up at least half of the 20 whp difference between a stock SOHC and a magnum SOHC. The exhaust ports on the magnum head are better designed, true, but that doesn't really become an issue with the stock head till ~150 whp (I'm going to keep citing my example of the guy who made 177whp on a stock SOHC head on a stock computer with ITBs and a longtube and a few other goodies).
I noticed a little gain with the magnum exhaust manifold, but who really expects to gain more than 3 peak whp from a shorty header?
and the ignition timing on the magnum is slightly more aggressive, but bear in mind that even an AFX race, which bumps up the redline (which goes a long way towards making more power if you have the right stuff), only makes maybe ~10whp over stock unless you have a big cam, LTH, custom IM, etc. Tthe AFX race is alot more aggressive than the magnum computer, so I wouldn't expect the magnum computer to really make up much of the difference either.
Then there's this neat dyno chart which shows a dyno of an R/T with the secondaries open (blue) and closed(red).
The spike at the end of the red is when they suddenly opened the secondaries.
20whp gain (with all the rest of the magnum stuff of course.)
You'll also notice that with the secondaries closed, it picks up around 10 ft/lbs of torque in the midrange.
I think this guy was stock except for a CAI and an AFX street/strip (maybe race?) He might have had an UDP. Note how the cam keeps making power a bit after it's peak

zpi28 · Post by **zpi28** » Sun Oct 11, 2009 10:05 am

Runner length is a huge factor with intakes. Why do you think a box intake is so good in the upper RPMs. Just like the difference in a TPI and LT1 intake..

ZeroChad · Post by **ZeroChad** » Sun Oct 11, 2009 3:57 pm

Pic fixed

Post by **occasional demons** » Sun Oct 11, 2009 8:42 pm

Damn Lamer, check your Photophucket once in a while.

Does this mean if something should happen to us, that all the pics we host through PB will be lost after 90 days?

Post by **racer12306** » Sun Oct 11, 2009 8:55 pm

I don't want to turn this in to a big deal, however.

Back pressure is bad. Period. No exceptions, you don't want back pressure.

zpi28 · Post by **zpi28** » Wed Oct 14, 2009 11:25 am

racer12306 wrote:I don't want to turn this in to a big deal, however.

Back pressure is bad. Period. No exceptions, you don't want back pressure.

I totally agree..

Post by **racer12306** » Wed Oct 14, 2009 11:36 am

Finally, someone who agrees and won't drag this out to being a 5 page thread about backpressure

hul kogan · Post by **hul kogan** » Wed Oct 14, 2009 12:05 pm

racer12306 wrote:Finally, someone who agrees and won't drag this out to being a 5 page thread about backpressure

Well then...

I disagree Frank, you are sooooo wrong. And I hate you.

Post by **racer12306** » Wed Oct 14, 2009 12:07 pm

Don't start princess

tominator · Post by **tominator** » Fri Oct 16, 2009 1:13 am

Go see that post that his stickied in this section, you'll find very informative stuff about the mag intake.

http://forums.neons.org/viewtopic.php?f=8&t=349006

I also wrote to Arthur for the porting of my mag intake and he was kind enough to answer me this,

Sick95SOHC

but basically what i did was remove the small throttle neck and replace it with a 60mm one, then i opened up the runners from the pathetic 38mm to 45mm. I don't suggest going that large because the mag runner walls are really thin, maybe go up to about 42-43mm, open up the ports on the head about 2mm wider than the manifold ports. That's pretty much all i did.

Fuzzyneon · Post by **Fuzzyneon** » Fri Oct 16, 2009 4:37 pm

racer12306 wrote:Finally, someone who agrees and won't drag this out to being a 5 page thread about backpressure

WRONG

back pressure equals mad hp

excon · Post by **excon** » Fri Oct 16, 2009 9:05 pm

wasn't the debate over flow?

Post by **occasional demons** » Fri Oct 16, 2009 10:10 pm

That was just some warm fuzzy sarcasm.