Rod Ratios
 

Here is all you ever wanted to know about rod ratios! It is a very complete and nicely done page.

http://www.e30m3performance.com/tech...ech/rod-ratio/

Re: Rod Ratios
 

good stuff jet

Re: Rod Ratios
 

So can I rev my 2.4l to 9000 or what?

Re: Rod Ratios
 

Didn't you and Jim both try that already? :D

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Ha, yea. Over 11,000 didn't work so well.

Re: Rod Ratios
 

Good Lord!!!!! Wow!!!

Re: Rod Ratios
 

I was kinda disappointed. Several "what if's" and no real world horsepower curve data for any specific engine. As far as a performance engine goes, the 4G63/4's are still in their infancy on a large scale. I'm sure the bigger name guys like Buschur, Shepard, etc., have their engine programs in full swing, but for some reason it doesn't seem like much of it has trickled down to the masses.

Re: Rod Ratios
 

I don't think Buschur has any real tricks up his sleeve, he never made that much horsepower. John and Brent definitely have some tricks though.

Re: Rod Ratios
 

It's called methanol and 60psi of boost.

Re: Rod Ratios
 

It's not as simple as throwing boost and methanol at an engine. Shepard has an engine program that is trying new things, very successfully I might add, and overcoming the pitfalls along the way. The part that's even more amazing is he's doing it with a manual transmission when most DSM's can't even get out of the 10's with 600/700 horsepower at the wheels.

Re: Rod Ratios
 

Buschur built Shep's motor.

A light car and the ability to run high rpms help him run quick. Some of the special stuff guys like Shep and Brent do is running a solid filled shortblock, running special headstuds, running some insanely high lift Crane cams, staying 2.0l so they can rev the car to the moon, running modified aluminum rods meant for some drag V8 motors. Brent tried a dry sump on his car a couple years ago and it ended up causing some crank failures. Early this year he tried not running coolant to his head, because some of the drag motorcycle guys that do his headwork ran their stuff like that, but it ended up warping the head during the burnout and cost him a race. Brent picked up a lot of power midseason when Nopi changed the turbo size rule for 4 cylinders with an adjustable clutch. They made him goto a smaller compressor wheel, but Borg Warner made him a a couple special ones that actually made more boost and more power with a smaller diameter comp wheel. I think he recently also removed his intercooler, so maybe that is why he all of a sudden had his trap speeds go up so much.

Re: Rod Ratios
 

I forgot about that. I'm surprised since Shep obviously has built more than a few, and I don't remember Buschur knowing anything special about filling blocks.

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i guess old mr boocher has a few aces up his sleeve. the secrets to his super shep engine are hidden behind his awesome mooostache.

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Free mustache rides for Joe.

Re: Rod Ratios
 

Ick.

Re: Rod Ratios
 

The biggest thing rod ratio's play a part in is piston acceleration. Plug your numbers into their excel database and you can find out the force that will be put on your rods, wrist pins, etc. You can use that to decide if they will take it.

Re: Rod Ratios
 

I was reading on buschur's www site just a few days ago about this; part of the deal w/ buschur sponsoring shep by building his motor was that he had to always have a backup built & ready to go. Buschur built the first motor and then a second. The first was installed in shep's car in april and the second motor, according to buschur, is sitting on an engine stand in his ship 'collecting dust' (I'm sure not really but you get the drift).

http://buschurforums.com/forum/showthread.php?t=13429

Re: Rod Ratios
 

he never responds to my PMs :(

Re: Rod Ratios
 

They stated on the Bushur forums that Shep still runs a '63 block. It didn't occur to me ask if he is still running 150mm rods. You could probably get a few more rpm by using a stroker style piston in the '63 block and still run the long rods. I wonder what Crane would say if one of use mere mortals wanted the same grind they use. I sure wouldn't mind seeing the specs on them .

Re: Rod Ratios
 

Crane has all kinds of crazy grinds for the 4G63, but most of them require some work to make sure the retainers don't smash into the valve seals/valve guides and the valves into the pistons.