Quick Revving L28

[Diseazd]

http://www.classiczcars.com/forums/showthread.php?42488-New-engine&highlight=

Ted.....Sorry I came in late to your thread. Is this the engine you're trying to build? I haven't finished it yet, but it sounds like what you're trying to build. I can't wait to see how it runs. The P79 head is ready to be bolted on. Good Luck..........Guy

[madkaw]

Dave,

I'm a little suprised these terms baffle you as much as you have been on this site. Not being critical and also very thankful for all your contributions to the Z world, just suprised .

Anyway we have kind of stomped all over this thread and not sure if you should start another for advice. i will PM you

[jmortensen]

Just found this thread. I'll just quickly agree with John, Dave, Leon, and others that what makes the engine spin up is its power. If you want it to spin faster (increase rpms faster) then you want more power or less mass to move or both. If the stroker makes more power, it will rev faster than the non stroker. If the cam makes more power, it will rev faster with the cam. The shorter stroke and resultant r/s ratio decreases piston speed when the piston changes from going up to going down, and this allows for a higher redline before the pistons shake apart, but this isn't related to how fast the motor revs. It has more to do with how high it can rev.

Dave....I agree with Jon Mortenson.....I've got two Stage II builds and two Stage III builds. Go with the Stage III cam. You'll be happy you did......you can really feel the difference between the two. Guy

Thanks, but I would actually say Stage IV if you're talking Schneider. Yes, for a street car. I had a cam that was .490/280 and it ran GREAT with my 8.3:1 L28 with SU's, was a bit small for triples. One could make the argument that a smaller engine needs less cam, and I haven't built an L24, but my inclination is still to go with something in the .490/280-290 range. I was pulling down mid 20's mpg on the highway with that cam and SU's.

Notching the block means removing metal from the top of the cylinder near where the valve opens up. Generally this is done by tracing the headgasket onto the block and removing metal with a die grinder. Same can be done for the head, which is called unshrouding the valves. Whether you need to do this or not is a different story. For Dave I think this would be wasted effort. The reduction in compression from removing the metal is probably about the same as the increase that could be expected from better flow. He's not racing, and doesn't have the rest of the head optimized (port and polished, cc'd chambers, etc). If it's an all out race build with custom pistons and really high compression, then it makes more sense to worry about that stuff.

Custom slugs just means custom pistons. That's not very descriptive in and of itself. Again for your usage, I'd get an regular old oversized cast piston. You're not turning super high rpms (so far as I'm aware) and the increase in cost of the forged pistons will net you no power and probably some piston knock when it's cold. It will be more durable if you miss a shift and over-rev or something like that, but how often does that happen?

[Zs-ondabrain]

I think I'm still on the OP's original topic, to a point. I'm building a motor, want it to be ballanced and high and quick revving, and need some input. Maybe some of what is explained to me will help the OP in his own build.

I HAD a clue as to the Notching. And was thinking Slugs were pistons. I'm looking at the .040 over pistons on zcarsource. http://www.zcarsource.com/piston-set-040-1-00mm-oversize-70-74-new_8_52804_50971.html Fair priced (under $200 and includes 6 Pistons, 6 Wrist Pins and Ring Set. Simple set. Using my ownrods that will be matched to each other. everything will be ballanced to the microgram.

The ballanced internals and lightened/ballanced flywheel will help it rev faster and cleaner. and obviously the bored motor, with stage 3 cam and new SU's should increase the HP to help get it in the upper RPMs faster.

Like I said, I want streetable with decent gas milage, but able to drop it down a gear and wipe the smirk off some idiot Rice Racer's face when I need to.

Dave

Edited December 21, 2011 by Zs-ondabrain

[madkaw]

Well Jon,

you just kind of confirmed everything I sent to Dave in a PM. I mentioned unshrouded based on what i have read from Racer Brown articles-that basically every head shoud be unshrouded for breathing purposes. Also for the fact that if larger valves are possibly installed and if the head needs to be resurfaced that unshrouding won't hurt -just help.

Glad you weighed in on the OP theory. Still like to see his results from a mixed batch of engine parts!!!

Couple of pics for you Dave