'91 Dyno'ed

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20 January 2014
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Just want to post this up to see what people think. "Power" mods (from previous owner) are K&N filter, DC Headers, and Magnaflow muffler (as far as I know). Car has 85K miles. Dyno was performed on this type of dyno: http://www.superflow.com/Dynamometers/Chassis/880_awd.php . Also, it was a little cold for California outside, possibly 50F. Personally, I think my numbers are a little too high. My friend who went right after me has a 2006 RSX-S with I/RH/IM Spacer had DJWhPw = 212 and STPPwr = 197. I'll update this thread whenever I go back with more mods. The important thing is I go back to the same place, ideally close to the same weather conditions, right?

IMG_20140207_093303960.jpg


IMG_20140207_084330591_HDR.jpg
 
282.9 seems a little high for a 3.0 with your mods. Most NA1 cars with I/H/E will dyno around 260.
 
Based on the legend it is saying you have 257 hp and 196 tq which is not bad for your mods.
 
Honcho: I agree. If I remember correctly, the DJWhPw and DJWhTq numbers are artificial numbers the tech used to simulate what my Dynojet numbers would look like.
venomous42: Yes, I believe so.
Rope: I can live with those numbers.
 
Anyone know the stock exhaust pipe diameter? I searched and found 1 7/8". Can anyone confirm this?

I went under my car and measured 2.25" which could explain my higher-than-expected 257whp. I previously thought it was the stock piping with magnaflow mufflers but it could be a custom exhaust. Also, does anyone have any experience going from 2.25" --> 2.5" exhaust (searched this too but I didn't find anything)? Butt dyno experiences are welcome but real dynos preferred.
 
Thanks Albert, super helpful. Looks like my exhaust is a custom job: 2.25" pipes with two Magnaflow mufflers. 257 whp makes way more sense now.

Anyone go from 2.25" to 2.5" and experience a significant difference?
 
I'm no expert on this but my reading suggests that exhaust gas velocity is affected by pipe diameter.
The manufacturers spend a lot of time studying exhaust gas scavenging and try to use pipe diameters that optimize this scavenging.
In theory your larger than stock diameter pipes would handle more exhaust volume but the velocity of the gas would be slower.
I think this means that bigger pipes don't necessarily mean more power.
 
JD Cross said:
I'm no expert on this but my reading suggests that exhaust gas velocity is affected by pipe diameter.
The manufacturers spend a lot of time studying exhaust gas scavenging and try to use pipe diameters that optimize this scavenging.
In theory your larger than stock diameter pipes would handle more exhaust volume but the velocity of the gas would be slower.
I think this means that bigger pipes don't necessarily mean more power.
Click to expand...

+1 totally right. Bigger is not always better. You want maximum flow, but with maximum velocity and scavenging. It is a delicate balancing act (just look at the current F1 headers) and there is a bit of art to it. On the NSX, big pipes only really matter for FI or major displacement mods like stroker. In fact, many aftermarkets have a "NA version" exhaust with smaller pipes and "FI version" with bigger pipes. SoS is one, I think.
 
Yep, totally agree with you guys, which is why I was asking for feedback from people who are NA and have gone from 2.25" --> 2.5" exhaust. To be honest, I'd be happy if someone chimes in and said "it's a waste of time, I didn't see any gains on the dyno, listen to Honcho and JD Cross here." I know it's different for everyone's setup, but it gives me a data point to prioritize my funds elsewhere (for now).
 
I went from the RM (2.5") back to the stock muffler (1.8") and was STUNNED at the improvement in throttle response below 5,000 rpm. I noticed no reduction in power.
 
Albert86: Still interested to see your results though.
Stuntman: Located in California, the smog check capital of the US. Yes I have cats. I'm leaning towards not going 2.5".
Honcho: Very interesting. What are your other mods?
 
Thanks naaman, but it only looks good at that distance haha. Far from a show car but I've only had her for two months.
 
Thanks Honcho and to everyone here. I think I'll stick to 2.25". From my search, it seems that the exhausts available to us (especially N/A) don't vary much in performance (+- 5whp?) but vary a lot in sound. I've already purchased Pride resonated test pipes. Now for the exhaust, I've narrowed it down to the Angus AP-X and Pride V2 strictly based on positive reviews of each product.

Can someone justify the $700 or so price difference of the AP-X vs. the Pride V2? In my opinion, no one was able to for an early model NSX in this thread: http://www.nsxprime.com/forum/showthread.php/161573-Angus-APX-vs-Pride-V2. I'm leaning towards the Pride V2.
 
Between the following two setups on my 3.0 liter:

'05 OEM exhaust manifolds, test pipes, '00 OEM muffler

'05 OEM exhaust manifolds, test pipes, adapters, GTLW

I'd have to agree with Honcho in that the throttle response down low definitely seemed better with the OEM muffler.
It definitely screams up high with the GTLW, but just seems to lack a little of the punch compared to the OEM muffler.

My reasoning was that it might have to do with the smaller diameter of the OEM muffler piping and it being more restrictive in comparison to the GTLW, therefore creating more backpressure which gives the sensation of being more "torquey" (especially at low RPMs).
But at higher RPMs it definitely seems to "flow" more with the larger diameter and less restrictive GTLW.

This of course was all measured by my butt, so take it for what it's worth, lol. (plus possible varying factors include weather, various weight reductions, and differences in unsprung weight between the feel of the two setups)

Bottom line though, I definitely agree with the well known fact that headers/newer exhaust manifolds are a vast improvement over the cast manifolds.
 
relapse said:
Thanks Honcho and to everyone here. I think I'll stick to 2.25". From my search, it seems that the exhausts available to us (especially N/A) don't vary much in performance (+- 5whp?) but vary a lot in sound. I've already purchased Pride resonated test pipes. Now for the exhaust, I've narrowed it down to the Angus AP-X and Pride V2 strictly based on positive reviews of each product.

Can someone justify the $700 or so price difference of the AP-X vs. the Pride V2? In my opinion, no one was able to for an early model NSX in this thread: http://www.nsxprime.com/forum/showthread.php/161573-Angus-APX-vs-Pride-V2. I'm leaning towards the Pride V2.
Click to expand...

Power. The AP-X is a free-flowing, straight through design and will give you about 10 more whp above 5,000 rpm. The V2 may actually reduce power slightly due to its complex layout. But, some people love the sound of the V2 so much they don't care about the power issue.
 

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