The truth about NA1 vs. NA2 OEM Header/Exhaust - Dyno inside!

Well, after hearing all the hype here on Prime about the 1997+ OEM Header/Exhaust combo, I decided to try it after I found out that Vance was selling his 2003 OEM Header/Exhaust/Cat combo in the classifieds. Everyone kept saying that the header design was going to improve overall power.

Since my 1995 has the NA1 exhaust manifolds and OEM muffler on right now, I figured I could get a good jump in performance for pretty cheap (~$1000 for the headers, cats AND muffler) yet keeping it all OEM. So I went ahead and did it and even had it Dyno tested to see if there were any gains.

So I went up to Speed Oracle Performance in Valencia to have it done, since Robert offered me a free Dyno if I got the work done.

Did a baseline run of 233.7HP & 188ft-lbs with OEM NA1 Exhaust Manifolds, NA1 OEM Muffler, NA1 OEM Cats, a Downforce Intake scoop, and the 18/19" Gram Lights wheels on.

After removing the NA1 stuff, we compared it and I was a little surprised to find out that all the diameters of the NA1 exhaust were EXACTLY THE SAME for the 3.0L to the 3.2L. INFACT, the piping diameter coming straight off the block on the NA2 3.2L Header is actually slightly smaller than the exhaust manifold off the 3.0L NA1! See pictures below. I must admit, I was quite surprised and a little nervous that it wouldn't show any gains.

Anyhow, we put it on. . .which took over a day to do the whole job. Here are some comparison pictures.

Front is the 2003 NA2 Muffler. Back is the 1995 NA1 muffler with custom tips. Despite the what it may look in the picture, the pipe diameter is exactly the same.


Here are the front header comparisons. Left is the '95 NA1 exhaust manifold. Right is the NA2 '03 header.


Here is a closer look at the pipe diameter. Note that the NA1 exhaust piping is slightly larger than the NA2 design . . Weird. . . (Again, Left is the '95 NA1 exhaust manifold. Right is the NA2 '03 header.)


Finally here's the dyno. The 3.2L graph is mislabeled. The peak is actually 248.3HP. Torque was ~197ft-lbs. This ends up being a gain of 14.6HP and 9ft-lbs. Gains were across the entire board!

Not a bad gain for $1000. But then again why not just pay another $1000 and go with some DC headers, GTLW exhaust, and some straight pipes? You'd probably gain another 15-25 hp and have a better sounding/performing setup. Not to mention the 50lbs in weight loss! Then again if you calculate the HP/$ it is about the same either way, so there is no real economic benefit, especially if you wanted everything to stay as close to oem as possible.

Pretty interesting.

Great info................I've always thought that aftermarket after '97+ was not worth the $$$$

Excellent work !!!

This is the kind of testing that I like !! :biggrin:

Since the exhausts between the earlier and later models are practically the same, your gains are probably entirely due to the better design of the headers versus the earlier manifold.
If you would now change the exhaust from the OEM exhaust to a more freeflowing design like the Taitec GTLW you would probably gain another 10 HP.

Thanks a lot for the info. And, once again, this NA1 header is a real piece of art !!!

Adrian thanks for coming out and allowing us the chance to work on your very mint condition nsx and to meet you in person.

uninstall was a nightmare. :biggrin:

im sure if you have an aftermarket exhaust, you would see 10-15 on top of that. i believe most of the HP where netted was from the exhaust manifold 3-1 collector pipe design. Since the piping after the colletor was all the same diameter.

bring it back for those brake lines and also get that front type R brace bar de-tweeked

If you have any questions about your car, give us a call.

It was pleasure meeting you Adrian.

Rob.:smile:

Adrian,

Thanks for the write-up... very well done!

Diablo360 said:

Not a bad gain for $1000. But then again why not just pay another $1000 and go with some DC headers, GTLW exhaust, and some straight pipes? You'd probably gain another 15-25 hp and have a better sounding/performing setup. Not to mention the 50lbs in weight loss! Then again if you calculate the HP/$ it is about the same either way, so there is no real economic benefit, especially if you wanted everything to stay as close to oem as possible.

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Simo, where's your write-up? :biggrin:



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nsx1 said:

Simo, where's your write-up? :biggrin:



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I never did one. I left all of my dyno sheets at Rob's that night. We ended up doing something like 10 runs that day. The first couple came out low (260sih) due to the very high tire pressure (42psi ). Once that was brought down (to around 37psi) I was running in the low 270's on every run, with a messed up A/F ratio. I didn't do a baseline, but i'm guessing my #'s would have come out as strong as, or a little weaker than Adrian's, due to my cars higher mileage. So i'm guessing with my I/H/E setup (which is typical) he would have similar or better numbers......

Come pick it up :biggrin:

here are a few more pictures from the day.



Both piping where about the same size.

I would bet that almost that entire gain is from the header... and if you did a back to back with another better flowing aftermarket muffler, the gain would be even more. I think its well documented now that the NA2 header is a good one.

So, are we to understand that the 97+ OEM headers are good for 15hp over the 91-96 manifolds? If this is the case, that would mean all of the other improvements Honda made to the 3.2 engine versus the 3.0 engine were only good for another 5hp. (270hp vs 290hp)

ericwgnsx said:

So, are we to understand that the 97+ OEM headers are good for 15hp over the 91-96 manifolds? If this is the case, that would mean all of the other improvements Honda made to the 3.2 engine versus the 3.0 engine were only good for another 5hp. (270hp vs 290hp)

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Not really. The 290 and 270 figures are measured on an engine dyno at the flywheel. What this means is that the rwhp of a 3.2 would be about 35 (20 bhp + 15 rwhp) more. Take away some driveline loss, differences in peak hp on the graph, and the fact that you might see a little more restriction from the extra flow on a 3.2 motor over a 3.0 might result in only a 30 rwhp gain.

Regards,

Danny

Eric, i was thinking the same thing :wink:

It would be interesting to see what kind of HP gains are to be had with an after market exhaust.

I got 2 aftermarket ones sitting here at the shop but they are for the AP1 and i dont have the adapter pipes. :frown:

.. we could just dyno the car with out exhaust.

lowellhigh79 said:

Not really. The 290 and 270 figures are measured on an engine dyno at the flywheel. What this means is that the rwhp of a 3.2 would be about 35 (20 bhp + 15 rwhp) more.

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Danny please help clear this up, cause something doesn't sound right to me.
His stock hp is 270, his rwhp is 234 that's about 14% drivetrain loss. Now what I've just read your saying he would need about 35rwhp to equal a stock 3.2L, am I following you correctly so far?
Adding 35 would put him at 269rwhp. So your saying a stock 3.2 290hp is putting out 269rwhp? That's would only be a 7 - 8% loss.

Help me understand this, before I go search the for sale section for some OE headers.:smile:
Thanks

Now let's see dyno with aftermarket exhaust and see what happens! Thanks for actually testing the whole 97+ manifold being better theory.

Jim jr said:

Danny please help clear this up, cause something doesn't sound right to me.
His stock hp is 270, his rwhp is 234 that's about 14% drivetrain loss. Now what I've just read your saying he would need about 35rwhp to equal a stock 3.2L, am I following you correctly so far?
Adding 35 would put him at 269rwhp. So your saying a stock 3.2 290hp is putting out 269rwhp? That's would only be a 7 - 8% loss.

Help me understand this, before I go search the for sale section for some OE headers.:smile:
Thanks

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I would expect the stock 3.2L motor to put down about ~250 whp based on a 15% drivetrain loss. Does anyone have a stock dyno for a 3.2L motor?

Forgot to mention that I did these runs with my 18/19" Gram Lights 57S Pros mounted. I wonder how the dyno would change with the OEM 16/17" Solaris wheels, which are slightly lighter. . .

lowellhigh79 said:

Not really. The 290 and 270 figures are measured on an engine dyno at the flywheel. What this means is that the rwhp of a 3.2 would be about 35 (20 bhp + 15 rwhp) more. Take away some driveline loss, differences in peak hp on the graph, and the fact that you might see a little more restriction from the extra flow on a 3.2 motor over a 3.0 might result in only a 30 rwhp gain.

Regards,

Danny

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HUH?!!!

If the 3.2 is rated at 20HP more, that translates to probably about 17 RWHP more. Sounds to me like you are going the wrong way Danny. You are adding power to the engine for drivetrain loss? The 20 HP difference is not RWHP, it is at the crank.

Ericwgnsx, I suspect a couple of things in the small HP difference. First of all, peak #'s and real world HP and most importantly torque, may be very different on the 3.0 and the 3.2. Second, the 3.2 may be on a more conservative fuel and ignition map, trying to improve emissions.

My car and Devin's are VERY similar, The motor builds are almost the same and the same turbo and muffler are installed. I used the oem header on my 2000 and he went with an equal length aftermarket header

mine

Devins


seems the torque trails off a bit more but not a significant difference

Hapa88 said:

I would expect the stock 3.2L motor to put down about ~250 whp based on a 15% drivetrain loss. Does anyone have a stock dyno for a 3.2L motor?

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I think your absolutely right, they should put down about 248 - 255. Just as a reference when I got my car I put it on the dyno (engine is all stock just k&n filter) with 19's on the back also, it put down 234.4.

all dynos are different and depending on how "Generious" the shop owner is, you get totally different numbers.

i gota same dyno as autowave, but they consistantly put out 30-40 more HP than my dyno on the same car/same mods. :tongue: not pointing fingures, just stating facts.

Compairing one dyno number to another dyno number is just about apples to oranges

best test is one base line of before and after your mod to see how much HP you gained. Also if you keep to one shop, all your runs will have the same consistant adjustment (inflated numbers) so you can see what each mods gained you.

Dyno is only a tool, not the authority on HP.

Also the DynoJet's are very loose on HP numbers. It only takes 1 beer to loosen those belts as oppose to 5-6 for the DynoDynamics dyno ( untweaked)

Best HP estimate from car to car / dyno to dyno is 1/4 mile time and speed and use reverse calculations based on your car's weight with driver inside to get your HP. :biggrin:

Hapa88 said:

Forgot to mention that I did these runs with my 18/19" Gram Lights 57S Pros mounted. I wonder how the dyno would change with the OEM 16/17" Solaris wheels, which are slightly lighter. . .

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You will probably see even more of a gain. Like you said, the OEM wheels are slightly lighter, but they also have a smaller overall diameter (essentially different gearing).

JeffShoots said:

Great info................I've always thought that aftermarket after '97+ was not worth the $$$$

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Indeed, this is excellent info, but it does not prove aftermarket headers won't free up additional power on a 3.2L. In fact, several past back-to-back dynos show 10-15 HP gain on 3.2L with just aftermarket headers. It is a smaller bang-per-buck on 3.2L vs. 3.0L, of course.

MvM said:

Since the exhausts between the earlier and later models are practically the same, your gains are probably entirely due to the better design of the headers versus the earlier manifold.

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It could be, but we certainly don't know this for a fact, since there was another variable: the cats. It's quite possible some of the +14.6 HP and +9 ft-lbs net increase was due to replacing the old cats (which could be 10+ years old) with a much newer and lower milage pair.

Great info, Hapa88!

bit of a hijack.
but was the NA2 full system plug and play on the NA1 ?
I was thinking to swap my NA2 stock setup onto my NA1 and swap over my NA1 aftermarket onto my NA2.