6200 rpm z24 stock

[ssnapz]

I'm getting tired of reading about how a stock z24 head will only turn 5k. My motor is stock inside. I have a custom built header ($40 to have flanges made, cut up a sb Chevy header, and about 4 hrs of cutting and welding), and 350 cfm Holley 2brl. Total of $100 in upgrades and I eat up zc Honda's shifting at 6000. Now I just put a cam in so once I get it dialed in I'll let you know where I'm at.

[Stoffregen Motorsports]

Are you saying you do run 6200 RPM or are you asking if you can?

 

Just because you can spin that RPM, doesn't mean that it's beneficial to spin it that high. If your power curve drops off before that, then running that high doesn't do anything for you. I remember when I had my first race car, I would spin the snot out of it before I shifted. Then I realized I would be faster if I shifted a bit earlier.

[izzo]

^^^ True story. My z24's would rev up that high. But they ran like shit. Maybe with your setup, it would be better. But at that high of RPM i could feel the power loss. Z24's are torque motors. they tend to do better at lower RPMS...

[datzenmike]

Better to say the stock Z24 runs out of steam by 5K. It was designed to pull a heavy ass 720 down the highway at realistic highway speeds of 3k to 3.5K and have very few emissions doing it. When you only have to rev that high you can do away with a head that moves a lot of air. The valves can be longer/heavier (they are slightly) because valve float isn't a concern. The intake ports can be lower down the side of the head causing a sharper bend into the combustion chamber, because it's never going to need to breath that hard. Compression is 8.25. Good for emissions not performance. Piston valve clearance is close because the lift is just fine as is and not going to be increased. Basically the Z series head was never designed with performance or future performance improvements in mind.

 

These 'performance' design flaws are hard to overcome.

[EricJB]

Are you saying you do run 6200 RPM or are you asking if you can?

 

Just because you can spin that RPM, doesn't mean that it's beneficial to spin it that high. If your power curve drops off before that, then running that high doesn't do anything for you. I remember when I had my first race car, I would spin the snot out of it before I shifted. Then I realized I would be faster if I shifted a bit earlier.

What? You mean your not supposed to rev it till it starts popping out the intake? Man, I've been doing it wrong all this time.

[ssnapz]

My motor still pulled up to 6200 I shift it at 6. Cam is in now and I'm still tuning it in so I'm only pulling 5500 now

[ggzilla]

Cam is in now

How did you run the engine without a cam? If you mean a hotter cam, it should run better at higher RPM. How does it compare to the stock cam?

 

If the stock cam still pulled at 6200 RPM, but the new cam only to 5500, it does not sound like an upgrade.

[ssnapz]

Got the carb dialed in now and it pulls to 5800 so ill add some timing. Cam is a little big so I won't see it till I get the turbo in. For now its good just beat a ls 400

 

[ggzilla]

Remember that if the timing is too far advanced, you won't be able to rev very high (but will have excellent power at low RPMs). So add the right amount of advance, maybe 34 degrees (Z needs less advance than L engine). Try it both ways.

 

Lexuce LS400 made 250 HP in a 3800 lb car. Z24 is 106HP in what? 3000 lb truck?

 

Still don't know what you mean by 6200 RPM. Before, you said you beat Hondas while shifting at 6000, but with a new cam can't get to 6200? The new cam may have a powerband below 6000.

[datzenmike]

Got the carb dialed in now and it pulls to 5800 so ill add some timing. Cam is a little big so I won't see it till I get the turbo in. For now its good just beat a ls 400

 

Turbos do not need big cams. All engines have a small amount of valve overlap when the exhaust is still closing while the intake is opening. Race or high performance cams have much larger amounts of overlap and a turbo will push air into the combustion chamber over the piston and right out the closing exhaust valve. This wastes boost pressure and looses power. A stock cam will work better with a turbo..

[ssnapz]

216 @ .50 with 450 lift @ valves lobe separation sucks 99 degrees but it was a regrind of a stock cam, I'm at 34 total timing 8 base. I'm still learning timing curve and Holley carbs. I'm just playing with the z24 until I have the $ to build my ka. If I blow it no big deal. And I'm at 2800 lbs and about 150 hp before the cam. March I get to do dyno runs. So far I just tune on my smog machine.

[ssnapz]

 

 

Turbos do not need big cams. All engines have a small amount of valve overlap when the exhaust is still closing while the intake is opening. Race or high performance cams have much larger amounts of overlap and a turbo will push air into the combustion chamber over the piston and right out the closing exhaust valve. This wastes boost pressure and looses power. A stock cam will work better with a turbo..

[ssnapz]

Good to know. I know almost nothing about turbos so ill make my mistakes on the napz not the ka. I plan on 6 to 8 lbs of boost only to overcome head design. This motor isn't worth pulling the head of to port and polish. Anyways I want the turbo experience AMD I'm told I can degree the cam to work under boost. Any advice is much appreciated

[datzenmike]

You can rotate the cam slightly to advance or retard it but overlap is overlap and stays the same.