PSI GUY

iTrader: (2)

Well, I took on a small project this week on a mini-stock car. Car is a 98 civic hatchback that races circle track at the local track in the 4cyl class. There are a lot of rules for the class, everyone tries to break them but they are pretty diligent with checking things so to keep the peace and keep the field even. They check compression, for cam gears, check for chipped ecus, not allowed variable valve timing and have to be stock oem parts right down to the airbox. The car I worked on was a good car, just didn't have the power to pull ahead and seems to always be a top 5 finisher but never close the deal. As far as a driver he is good, car handles great, has a good setup but just lacks power whereas the others have some work done to keep them ahead. Engine in the car is a OBD2 JDM D15B non-vtec, basically a 1.5 version of a Y7. So, where could we go as far as hp increase without getting into internals and we decided to throw some old parts that were kicking around together to try something. But first, we needed to get a baseline for the car, went to a buddies shop and put it on the dynojet and made a whopping 101whp and 96wtq......lol. Bonus to the situation is that the stock airfuel was a solid line at 11.50, so we knew there was some power to be made just in leaning things out.

I decided to take the center feed intake off the engine and throw it as far as I could and installed a Y8 intake manifold. I plugged the IAC ports and installed the three wire EACV throttle body on the manifold. I left the stock injectors in as I figured it would be a good base to start with as it was rich and more air would lean it out, I had a bunch of other sizes to work with when we went back to the dyno to dial in things. So, better manifold.......check.....now how do I get more air in the engine?

On the shelf I had an old Y8 head as well, took it apart and compared the rockers and by chance they all bolt up the same on the heads. So I took the Y8 cam and set it in the non vtec head and it fit perfect......hmmmm. Decided to take the rockers apart and lock up the rockers to lock the intake on the high cam as technically, it wouldn't have variable valve timing. In the end I used a long pin from a b series rocker and machined 0.030" off to shorten it and used the small pin from the d series as well to lock up the rockers. Installed the cam and rockers minus the lost motion assemblies and plate into the D15 head and torqued to spec. Adjusted the valves, put the intakes a bit looser to make things happy and the engine fired right up and idled. I had to open the throttle plate up a bit to take a bit of the chop out of the sound so it didn't attract attention from the bit of lope at idle.

Went back to the dyno, tried a few different ecus, an OBD1 p75 made the most midrange but he's not allowed to run a conversion harness so we ended up putting the stock P2E ecu back in. Timing was set at 16 degrees and the injectors were left stock as it put the airfuel at 12.50 right to redline which was great. Overall I was pretty happy and he is very eager to try it out tomorrow in practice. Not bad for an hours work and very little money. After the race I am going to take it back apart and inspect for wear on the rockers if there is any. Stock cam and valve springs shouldn't wear the rockers I don't imagine but will still have a look after a race to see. As far as doing this on a street car, I don't see why you couldn't. It is a bit more taking off as it would be with any cammed engine but for an engine that lives between 5000-7000 rpm on a track, this was a great upgrade for the last two races. Over the winter we will build a new better engine for it but this one should raise some eyebrows at the track this weekend and the tech guys should be scratching their heads.

Dynos were three days apart, same weather, and both corrected SAE. Here is a before and after, should be lots of fun.

WheresmyRice

Sounds fun

r_Senik

Woah. Nice numbers. He ever thought of doing y8 exhaust manifold and a b series tb with the 99-00 civic si stock intake arm and box?