new to this forum, I have a 98 z24 (2.4) that I am getting ready to race at my local 1/4 mile dirt track, I want to keep up with the civics and neons, my question is how much compression can I run before the knock sensor retards the timing? I am doing the "secrete cam" and 2.3 injectors, and port and polish. ( I am thinking of milling the head for more comp. Thanks.

are you allowed to tune the pcm?


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

as far as i know high compression in these engines has absolutely zero bearing on knock. i just witnessed a datalog from paul tjepkes' 201whp all motor dyno run and it had zero knock with domed pistons and .040 over bore.

if you are allowed aftermarket pistons go with wiseco domed.

if you are not, go with the 99-02 FLAT TOP pistons and retain you're 98 head but get it decked and install a set of sivalves.com stainless steel valves. doing this you're compression is going to go up. the valves have less 'dish' to them than stock and the pistons you have in that engine have a tiny dish to them.

or, you could always do the 2.3 head swap. this will increase compression quite a bit.



I must confess... I feel like a monster!

the rules state "stock" , but I know there are a bunch of guy's not stock. I considered tuning but don't want to spend that much money on tuning because we have a $500.00 claim rule, any one can come to the track with $500 and take your car, you get the money and your seat, they get the car, so the mods I am doing are what I can do myself. what does a tune cost anyway, what all is tuned, running 2nd gear all the time I dint think I will be much over 6000 rpm and only about 60 mph. in the straight.

on a $500 dollar claim switch makes, your never gonna keep up with the hondas, unless you have a very well built ecotech. The 2.3 and the 2.4L are better on the 3/8 to the 1/2 miles. My buddy runs a saturn w/locked diff that runs pretty good too very well built ecos, 2.3 and 2.4L


fast cavy

I do plan on running at a 3/8 mile asphalt up the road now and then, just want to make sure I am not last. and if I do loose the car for $500, I can build another.....to go faster. so if I do the cam swap, inject. up the comp. do I need to tune the computer?

no but it would help.....When I got my computer HP'd it was only like $150 for the credits.


fast cavy