I'm no expert on the manifolds that are being used. but from what I read earlier in the post, I understood the LO intake didn't flow as well as the stock one. The larger TB wouldn't affect the intakes flow that much unless the TB was that much smaller than the intake port on the manifold. The fact that he used the larger TB just resulted in taking away some of the restriction from the TB and showing that its the Manifolds restrictive nature.
He really didn't gain any power. What he did was allow the car to accelerate faster when the RPMs are higher, That is usually accomplished by restricting airflow.
I did this experiment with my older car granted it was a V-8 and not an I4 but the same stuff applies.
my original engine was a Stock 350 engine in a 1984 Camaro.
What I did was I changed the manifold to an aftermarket High flow manifold, it brought the power curve down into lower RPMs.
I then put a manifold that provided faster airflow, but at the cost of more restriction. The result was more horsepower in the upper part of the RPM band and less torque, but the torque was also moved into the upper part of the RPM band.
Now provided the engine still gets plenty of air and fuel to fill the cylinders you won't loose horsepower, but you'll gain torque. And Torque is what gives you speed, HP is what provides the acceleration.
11 whp gain on just a simple part you can get from the junkyard is pretty damn good. <br>
log style vs 4 into 1 style humm! they say that the stock intake flows better also? humm! i need to see the graphs to compare where the torque fell off at. Because my brain is telling me that the intake that makes more power in the upper rpm ranges flow's better. we need to see where the air fuel ratio it during the run also. to see if it is a tunning issue.
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see ya!
It is quite possibly a tuning issue. and I was just going by what I was reading in the forum. I know this rule applies to ungoverned V-8's and to TPI injection. Whether it applies to I4's and V6's with MPI your guess is as good as mine.
themarin8r wrote:11 whp gain on just a simple part you can get from the junkyard is pretty damn good.
Now here's someone that gets it......
10+ wheel horspower for under a $100 and a hour or two of your time.
No other changes and no tuning!
Probably more power in there with some A/F tuning.
If I owned a 2.4 I'd be on ebay looking for one.
I have acess to a 2.3 HO manifold, so we may be test fitting this weekend. What is the TB size on a 2.3 HO manifold? Do you know if the 2.4 TB will mount, or does it need to be modified? <br>
FU Tuning
hey guys anyone interested, i have an ho and lo intake manifolds, with throttle bodies, let me know if anyone needs ones.
Did you match up the ports at all? <br>
O noes!
If you have no way of posting the sheets, you could go to say kinkos or a place like that, and fax me the two sheets, i will then scan them and host them on a site and post them up. if you want to do this email me at neternms@netscape.net and ill give you my fax number. or you can always find a friend in the area that would scan them for you, hell maybe even just scan them at a place like kinkos and then just save it to disk there and put it on you computer. <br>
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Or you could simply do a 100 rpm data sheet where every 100 rpm you list power and torque. That should take all of 5 minutes to do. <br>
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John Higgins wrote:I have acess to a 2.3 HO manifold, so we may be test fitting this weekend. What is the TB size on a 2.3 HO manifold? Do you know if the 2.4 TB will mount, or does it need to be modified?
the 2.3 HO TB is a 56mm
the 2.4 TB will fit but you have to open up 2 of the holes for the larger bolts. <br>
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64Cutlass Convert.
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thanks OLDsman1. We are going to work on this tomorrow. <br>
FU Tuning
I just need this clarified cause it's bothering me:
Quote:
What he did was allow the car to accelerate faster when the RPMs are higher, That is usually accomplished by restricting airflow.
Quote:
I then put a manifold that provided faster airflow, but at the cost of more restriction. The result was more horsepower in the upper part of the RPM band and less torque, but the torque was also moved into the upper part of the RPM band.
Quote:
Now provided the engine still gets plenty of air and fuel to fill the cylinders you won't loose horsepower, but you'll gain torque. And Torque is what gives you speed, HP is what provides the acceleration.
You guys keep talking about the HP gain, well ok. A gain is a gain. But, a gain is not a gain if you lose somewhere else worse than what you gained. Uh, read that again, I had to and I wrote it
. This is why you need to look at the dyno chart before you go buying parts. Peak HP does NOT tell the whole story. My 2 cents. <br>
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anything about the dyno sheet? <br>
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you know... im finding it awfuly hard to belive that you can snatch up 11 whp from an intake manifold and a TB thats only 4mm larger. Theres some other force going on there. If you can truly gain that much power from a log mani, a serpent manifold should yeild some astounding numbers. <br>
"it may mean nothing but I don't care..............it don't feel like nothing"
the butt dyno loves the ho mani and throttle body........so do my ears
yeah i'm with excidium it probably gave good peak power but his powerband could have shifted and his tq and hp curve are different and possibly lower with a higher peak. <br>
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1) As soon as i saw your findings, i wanted dyno sheets. After reading the rest of the post, i still want dyno sheets
I wanna know where the trade-off is here. The torque loss is negligable, depending on where in the powerband it was lost. Its interesting that the peak hp shifted down though.
2)John Higgins, check this out
ny-jbodiesHOmani-how-to If you wouldnt mind, let me know how it goes. Im interested in doing this.
Cam: I'm working on polishing the manifold now. Hopefully nest week, I can actually start getting it ready to be mounted. I will post once I get it on. Depending on how it goes. I'm thinking about doing a dyno with the stocker on there and the HO manifold. Would be interesting to do at the Bash. <br>
FU Tuning
The interesting thing, when the LD2's manifold was changed to the log style one in 90 the LD2's HP rating went from 150 to 160. <br>
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I've been trying to keep up with information regarding this manifold (HO/LO) for over a year now. I for one, do not want to sacrifice lower RPM torque to gain a little HP. I enjoy the "powerband" being a little bit low. Now, granted the manifold looks good and sounds better than the stock one, I don't see these as good enough reasons to use this manifold. True, there are success stories and Karo is running a kick-@!#$ engine with this manifold, but i've also heard problems about it. If you're that curious about what it does/what it will do, buy one and put it on your car. I'm still skeptical about doing this. I believe that just getting a larger tb on your stock manifold will yield some gains but probably not 11 whp. Personally I'm thinking about the RSM manifold with the 62mm tb so if anyone has information about that let me know.
Well I'm working on putting the manifold on. I either need a close up picture of a 2.4 TB on or a better idea of where the TB sits to connect the cables to it. Thanks <br>
FU Tuning
White_Z wrote:Just by the looks I don't think that it is more restrictive, and wouldn't that cause a loss of power???? It also has a bigger throttle body which would flow better, especially at HIGHER rpm's
WHAT? ok, so i decrease torque and thus i increase power... uh... no. Horsepower is a function of torque an rpm, fella. To increase horsepower, i need to make more torque somewhere. He lost peak torque, but gained higher rpm torque. His torque has been shifted around so he makes power in a usable part of the rpm range. Who gives a rats @!#$ about tug boat torque, cause you're not gonna use it while racing. His overall power curve is different now, and he should make more *average* torque, and he should make it higher.
Runners that flow LESS will favor LOWER rpm power. Runner's that are longer, also, will favor low RPM power. Runners that have smaller plenums will favor lower rpm power and will have better throttle response.
Now, the 2.3 manifold is more restrictive than the 2.4, but not overly so. The runner lengths are also different, but not by much. What the major difference lies in is this : the LO and HO plenums are huge compared to the 2.4's tiny plenum. The 2.4 manifold was tuned specifically for tug boat torque.
What gave him the extra power boils down to 2 factors. #1 INCREASED PLENUM VOLUME. Larger plenum volumes favor high rpm operation, but will hurt low end torque production #2 LARGER THROTTLE BODY. Again, the 2.4 throttle body is designed to promote the production of tug boat torque, thus purposely too small! We don't want that, so we use the 2.3 tb which is actually perfect for the 2.4L.
Personally, i will chose not to use any 2.3 manifold. The 2.4 runners are tuned perfect for the engine. It just needs a bigger plenum. And, there are cheap ways of increasing plenum volume WIHOUT getting a new manifold.... <br>
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crap i just quoted the wrong person, teehee. sorry. <br>
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