Well, I have a B18C5 with a JUN head package, Mugen headgasket, Hy-Tech header, carsound cat and 2.5 inch exhaust, I also have a JUN ECU and a V-afc. After getting used to the car initially, I have noticed a flat spot in the powerband between 6200 and 7000 with the V-afc at stock settings. I have a 5700 rpm VTEC point. I have leaned it out from 6000-7500 and had good results to a point, I am just looking for advice on my potential bottlenecks and what not (IE catalytic converter, exhaust, etc).

I just recieved my Victor-X intake manifold, and am planning on getting a testpipe and full race exhaust made (both for track only events). I hate this flat spot and would hope I could tune it out with the V-AFC/ Any help from you tuners would be appreciated.

 

do u have any work to the bottom end?

Never Mind the Test Pipe, just Gut out the Cat.........

nick

 

Don't ever gut a cat, do you realize how much a used cat goes for?

That's like throwing money away, not to mention harmful for your health.

 

First question. Stock bottem end, only 11:1 compression ratio with Mugen Head gasket.


I would gut the cat (I am no conservationist) but I have emissions to deal with and the stench and $1000 fine are unappealing to me at this time, I also heard that gutting a cat can hurt performance. I think the JUN ecu is dumping to much fuel at VTEC hi lobe engagement and the cat is restricting my exhaust flow. from around 4500 until VTEC and after 7000 the power is excellent.


[Modified by slowerthanu, 5:51 PM 6/22/2002]

 

Just GUT THE CAT!!!!

 

That's fine if that's your thing, but I rather use a 2.5" test pipe and sell my old cat.

That's just me though.

 

That is wierd, I have not heard of any problems using the JUN ECU. I pull hard from 6000 all the way to 9300. I am using Hondata though, and I am not fully tuned (timing not touched)

Please post your dyno when you are done

 

That is actually my plan when I have time, new job at hospital, they work me too much. I really do need to dyno it in order to get an idea of what the a/f is and were my power is, i have got a feeling it isnt going to be nice and straight, plus I hate getting on it on the street to tune with it. It oddly enough does'nt feel like a power loss, it just feels flat, like it levels off and then starts making power again.

 

I have the same setup as you, minus the header Anyways, with the JUN ecu I would not touch the VAFC unless you are on the dyno. try moving your Vtec x over to 6000 or 6200. 5700 is to early, that's why you probably have the flat spot.

I have a VAFC but have not messed with the fuel settings, because I know i'll jack them up. I am waiting to get on the dyno, before I mess with it. Other than the flat spot, do you like your setup? You should be putting down some solid power.

 

I love the setup as a whole, I have the road race ECU program which runs richer fuel settings so I have the V-AFC so I can trim it down if need be, I will try the higher VTEC setting though, thanks.

 

I am sorry that I can not help you out, but I was just wondering if you had dynoed your setup. Reason being is that your setup is exactly what I am planning... Info would be great.. Thanks!

 

ttt

 

the only way to fix the problem is on the dyno...

 

Just curious...what kind of intake are you using?

 

Don't use the VAFC for fuel tuning. The only thing it's good for with the Jun ECU is adjusting the VTEC x-over. The Jun ECU run a higher clock rate and I've been told by more than one person that the VAFC is basically too slow for the Jun ECU. I know a couple people who tried using it and they said the VAFC actually hurt performance.

 

hmmmmtough one
although i dont like the idea of the thin head gasket
did you dial in your cams as they are prob slightly retarded on both if the gears are at zero
and your valves are prob real close to the pistons
mine are like 30 thou... but thats with JE 12.5 pistons
other than that
I have no flat spot anywhere
and dyno dyno dyno

 

ditto

 

I would raise the vtec/xover a little higher, speaking from experience.

 

even with high compression..those big lobes can be like hitting a brick wall

 

yah if you dont have the fuel it isnt gonna cut it
DYNO

 

Gutting the cat creates a rather large abrupt change in exh diameter which
can actually do more harm than good.

 

AHAHAHAHAHAHAHAHAHAHAHA
All 96+ ECUs are faster than their older counterparts. But thats not the reason
why the AFC doesnt work well.

 

What kind of damage r we talkin about?

Nick

 

Your flat spot is due to your enfine not beingable to breathe. Your taking in more air and your exhaust system is to in adequate for those cams. You need a header that has a 2.5 inch collectorand either a 2.5 inch cat or testpipe and a 2.5 inch exhaust with those cams. VTEC cross over on the ecu is there for a reason dont change it. JUN does not recommend a VAFC with their ecu.

 

He has a Hytech header! and 2.5" exhaust!