Finally made it down to Street Flight dyno yesterday, even though I was having some car issues.

This is a JDM ITR header with the inner welds smoothed (dremeled) and rewelded on the outside. Also using a 2.5" test pipe.
I measured the collector size on each header.
The JDM ITR has a 2 3/8" collector while the USDM DC 4-1 has a 1 7/8" collector.

Final results were a maximum of 166.2 WHP and 140.6 TQ.
Thats a gain of 6 WHP and a loss of 1/2 FT-LB of TQ.
As can be seen...some midrange power was lost...on average around 1-2 HP and 2-3 TQ betwwen 4000 and 5300.



I was pretty surprised with the gains especially considering I already had a 4-1 aftermarket header before.





[Modified by HX_Guy, 8:43 AM 9/4/2001]

 

nice

finally a good compairson....definitly gonna get the DC JDM very soon...

 

um, i think he is saying that the JDM header is much better than the USDM DC 4-1. Again, this isn't clear from the dyno or the post. Which is which man?
-C

 

Blue line = JDM ITR header
Red line = UDM DC 4-1

 

woah, I just realized this is on a b20Z. The flow characteristics are going to be way different on a B18C (especially at 8-9K), so any assumptions on the difference on a B18 would just be speculation. Good numbers man! You'll be making crazy power once that Vtec head goes on.

 

What VTEC head? Who said theres gonan be one? Hehe

I have pretty good high RPM numbers because of the Crower cams...if I were to drop a stock B16 head on my block...I probably wouldnt see more then 170-175 WHP since that seems to be the average of stock head/block B20s. Also..that would be at around 7500 RPMs.

Im willing to bet that if I rasie my revlimit to 7500 or even 8000..I can make 175 WHP with my current setup. If I port and polish the LS head...maybe even around 180-185 WHP...who knows?
This is all with a stock bottom end so far..whatever head I go with I plan on some higher compression pistons and stronger rods.

I dont know..it will be more expensive to go with a worked LS head...but theres something I like about saying "all motor, NON VTEC"

 

all-motor non-vtec...

kinda like an oximoron? haha

 

Hey HX guy,
Have you tested the difference between the short ram and cold air yet?

Do you have a dyno plot of pre-cams and post-cams w/the cam gear tuning on same graph.

When are you going to the track next, I'd be very interested to see how it works out. Because you might want to move around you torque curve to match your GSR gears. 1-2 shift(@7000): ~4100rpm, 2-3: ~5000rpm, 3-4: ~5300rpm.

 

Awesome man!

I love watching your progress... The bigger collector really helps out on the top, huh.

This weekend I watched the near completion of a B20 swap into a 91 CRX. That's just gonna be sick! Poor guy still has stock wheels with 185 width tires, doubt they're gonna last long, hehe.

I also moved my cam gears from +6/+2 to +3+1 and richened up a little. I lost a tad below 4000 rpm, but the middle and esp from 6K up feel MUCH better. I think with a good header, I should see at least 5-10 HP on top...

BTW, did you also remove the anti reversion chamber like the guy from the ITR forum? It looks like it opens up the collector, but wonder if it really helps?

Take care,

FB

<EDIT> do you dyno like every week or something?

 

Havnt had a chanceto test short ram vs cold air yet..but I will real soon..I wanna know as well

Heres a coiple dyno charts of pre-cams vs post-tuned cams (but without the JDM header)...Ill post that in a new post...since Im proud of the results

 

Berkel: I did not remove teh anti-reversion chamber..didnt even know anyone did that until I read it on the ITR board after I had the header on already.

Im not sure if it helps or not..it may be too big afterwards and cause more midrange loss...so I think Ill leave it at 2 3/8".