427 small block

anyone here read the story of the 427 sb build in mopar muscle? what size cam was used and what hp tq did it make? can't find the rest of the arcticle.

Thats one main reason i dumped MM, all those engine build shootouts and very little real info and specs

yeah, i don't get it any more either. just picked up the oct issue at wal mart and now all i can find is jan issue.

The second part of the article will run when there is space for it. Should be showing up soon. The engine was designed to mimic a Viper power curve and that is basically where it ended up. Basically a 500/500 type of motor with an 800 rpm idle.

Andy, why not a 426???

It is what it is. 427.2 ci according to my calculator. I suppose a marketing person would've called it a 426.

i was thinking about rebuilding the 408 one more time before moving on to the 499 project,but i ran the 427 combo across my desktop dyno and it only made a few more hp than my 408 using the same cam and heads. not sure this build would be worth it. i would need a 4.125 crank,new flat tops and 6.2 rods.

Remember the hot rodder rule of thumb....every Dollar invested in head flow is roughgly worth 3 in the short block.

Andy I thought you did it just so you could put those Chevy "call out" badges on your fenders

I have a 427 build I started years ago. Just don't need it.

It is 4.125" bore with a 4" stroke. Considerably more worth while than a smaller bore with longer stroke. You have to remember stroke pretty much moves your power range down in RPM. I did it due to J heads and 59 degree lifter angle. No neeed to turn it 8,000 with a 4" stroke can make the same power at 7,000.

Main reason we did it was to make as much torque as possible without breaking the bank. The 4.125 stroke is about the limit in terms of reasonable solutions. The next step up requires more money for balancing and you start to have clearance problems with the oil pump pickup, etc.

Power peak with the Stage III heads from Hughes is 5800 rpm which works out to 155+ mph in this car. The car will pull it on the back straight here at Portland International. If we tow to a faster track we might bump up the rev limiter a little bit and see where it stops pulling.

This isn't a drag race motor so we didn't care about big peak numbers. Just looking for a smooth idle and tons of torque down low so the car would be nice and easy to drive.

when i run the numbers for the 427 and keeping current compression with the 408(10.65) the 427 losses 6hp but gains 6 ftlbs tq. bump the compression to 12.0:1 and gain 17hp and 24 ftlbs tq over my curreny 408 combo. this 427 combo would cost me about $2500 to do using most of my 408 parts. i think i'll pass on this combo.

With the same heads once you go over 4" stroke you're rate of gain per cube increase will slow down, above the torque peak the RATE of acceleration slows as the VE drops, in your case (same heads and compression)the longer stroke isn't getting the proportional rate of increase in airflow to offset the increase in frictional losses.

Long stroke small blocks like Andy's example are built and tuned to achieve the highest average torque, and a flat broad torque curve without much variance (achieving at least 85% of peak torque over a ~2800-3400RPM band...the right intake manifold is important here too)...peak HP is not really the primary target. If Andy wanted more hp at that approx size he would have bored that 340 Resto (siamese) block to it's max ~4.22" IIRC) and shortened the stroke to something like the 3.79" , plug that in and you should see more HP per cube but a little less peak torque...and at a somewhat higher RPM...if you really examine it you'll see the frictional losses are lower....because the piston speed is lower at any given RPM. This is most apparent above the peak torque RPM.

Our block is a water block. Max bore size is 4.080 and we're currently at 4.060. Should last a long time if it doesn't get any damage but it won't be capable of very many rebuilds.

A larger bore size would've made more power but that wasn't really an option at the time. Also, I wasn't too sure if the siamesed block would work for our application. I didn't really want to get a ton of money invested into the motor and then fight cooling problems at the track.

i'll have to pick the mag off the stand and check it out, i'm about ready to do a 427" but with a massaged 71 intake and exhaust manifold, and "gasp" J heads..

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when i run the numbers for the 427 and keeping current compression with the 408(10.65) the 427 losses 6hp but gains 6 ftlbs tq. bump the compression to 12.0:1 and gain 17hp and 24 ftlbs tq over my curreny 408 combo. this 427 combo would cost me about $2500 to do using most of my 408 parts. i think i'll pass on this combo.

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What all is done to your 408?