last night i tuned my ap1 on the dyno once again. since the last time i tuned it i've added the gm iat senosr and a hks 3 inch single exhaust. for those of you who did not see the first thread, here's the link:

https://www.s2ki.com/s2000/topic/884...yno-tuned-ap1/

at the moment, the car has the following modifications:

- diy 3 inch intake with blox filter and blox velocity stack
- hondata intake manifold gasket
- plm header and 2.5 inch test pipe
- hks 3 inch single exhaust
- injector dynamic 1000cc injectors
- e85 fuel
- gm intake air temperature sensor
- haltech platinum sport 1000 ecu

these were the final results:



and here is a graph comparing the previous tune with the stock exhaust to the current tune with the hks 3 inch single.



as you can see, i picked up mostly mid range and about 1 hp up top. i still had that dip after ~8200 rpm and my buddy suggested we test a longer intake pipe.

we added about 5 inches to the current intake pipe and this was the result:



my buddy was right! the dip after 8200 was due to the length of the intake. it wants a longer intake pipe. i lost power in the mid range but that was because it went rich. the afr's went to about 12.2-12.4 in that area. i think if i leaned it out i could've gotten the power back to where it was with the shorter intake pipe. up top where it picked up power it leaned out to about 13.2-13.3 so i think there's probably 1 hp to be picked up. definitely would've been over 228 whp if i would've dialed in the fuel with the longer intake pipe.

here was a picture i took last night on the dyno when we extended the lenght of the intake pipe. the bright silver pipe connected to the filter is what we added:

 

nice.. I always tell people that motors always make better power with a LONG intake.

Go to lowes and pick up like 5ft 4 inch pvc and see if that helps.. usually over about 220hp a 3 inch intake tube is too small.

 

it depends. i've played with intake length on k-series and the k20's tend to like short intake pipes for the most part but there are exceptions.

i want to try 3.5 inch piping for the intake but i think i am going to upgrade the throttle body as well. i don't think a 3.5 inch pipe will make much of a difference with the stock throttle body. i'm leaning towards the full blown motorsports 74mm throttle body.

i also think that the 2.5 inch testpipe is a restriction on the exhaust side of things. i may upgrade that to a 3 inch as well.

 

A long intake (like the AEM V1) causes a positive pressure wave that increases the intake charge of the NEXT cylinder in the firing order, and a very short intake (like the PWJDM) causes a positive pressure wave that increases the charge of the current cylinder. If the length falls between (like stock), then the positive pressure wave just bounces off closed intake valves. Obviously the exact lengths are determined by the targe RPM that you want the peak benefit.

You can't get any shorter than the PWJDM, which acts like an intake that is less than an inch long. However, if you play around with steps in the pipe diameter at various points (like the AEM V2), you can create resonant humps in multiple places in the RPM range..

 

Forgot to mention ... that torque curve looks sweet!

 

Makes me want to get tuned ASAP sense I have a similar set-up, but I'll be getting a bigger TB first. I'd imagine that the 2.5" test-pipe is holding back the gains from the 3" exhaust.

I'm curious...what is VTEC set at? 5500?

 

Nice. I have the same header, tp, and exhaust. I just bought flashpro. I want to ditch the HKS and go with berk because it seems like there is a smoother transition from the 2.5 collector to the 3 inch tp

 

vtec is set at 3800. on the previous tune, vtec was set at 4700.

 

Nice. Only 2200 lower than OEM lol You're probably loving the broad powerband.

Thanks for sharing the results from the intake to. I wanted to do a test very similar. I'm also wanting to test a 3.5" pipe.

 

Go for 3" test pipe. I don't think there's a header with a 3" collector though, not sure if that'd help.