Building a 302 / 3.00" stroke / 8,500 RPM, V-8 Car Options

[drive-ability]

I have started gathering parts to build a large journal 302. This is the engine this car needs to really work. The 350 is made to move a truck, where as a 302 makes the best balance of HP and torque. Ya the parts are expensive about 3 times the cost of a 350 but you only live once. (IMG:style_emoticons/default/beerchug.gif)
I'll keep you V-8 guys posted!

[byndbad914]

Driveability - I would be scared of a short block that was under $5K and meant to live at 8500rpm. I built a number of small block Chevy race engines including my own and can promise you I built either 3 or 4 302s (can't recall if we used a 400 block and spacers on one - I think I actually built one of the 302 cranks into a 400 block by getting fuzzy - about 6-8 yrs ago).

I did one for a "budget" and in the end I think the stock rods were the weak point and couldn't handle it even with ARP bolts, shotpeened and blah blah. 8500rpm is a LOT of rpm guys! Think of what it takes to make a NASCAR engine live at that rpm for a few hours of running (now they are above 9K but just a few years ago at 8500rpm those engines had serious guts).

And by "live at 8500" I mean put $$ in the crank, rods (really strong steel I-beam or H-beam, but H-beams can be heavy - mine were), pistons and valvetrain.

And wait until you have to change the chrome-silicon spring set each year if you really run it up to that rpm a few track days. Maintenance on an 8500rpm motor is not cheap as that will take a pretty serious cam.

If you want a 302 to live at 8500rpm, it is going to cost you some bucks frankly. I have about $10K in my destroked 400 (353 cubes with 327 crank - a combo I built a ton of for circle track motors and another member mentioned this combo earlier) and I only run it up just over 7300rpm and really don't have anything exotic - stock 400 block that I machined for splay-main 4-bolt caps 2-4, stock 327 steel crank, Eagle 6" H-beams, SRP off-the-shelf (OTS) flattops, Canfield 195cc heads (with serious port work now), cheap(er) Probe shaft-mount rockers, solid tappet Elgin cam that was $60, so forth. Nothing really that outstanding, tho' all the parts are right to spin to 8500rpm, but not live there. The cam won't get it to 8500rpm, but the other parts would go there a couple times (IMG:style_emoticons/default/biggrin.gif)

I built a DZ302 to shift between 8500-9000rpm for a 69 Z/28 the guy used for drag racing. Big roller cam, big heads (220cc IIRC), crower crank, ti valves on the intakes, Jesel shaft mount rocker arms, etc. The short block was definitely not cheaper than $5K - the Crower crank was about $1500. I think that was about a $15K carb to pan but it lived at that rpm no problem. I used aluminum rods in that one IIRC. That or another high rpm 302 I did for a Z/28 was a steel I-beam rod motor.

BTW, I think Eagle is making a 302 crank now, but if you are serious about 8500rpm, I don't know if I would trust the Eagle tho' I have built some serious motors with their cranks. By the time you find a stock crank and machine it, lightweight the counterweight, etc and do a heat treat of some sort, probably could just get a Crower crank or similar quality and pay the $1500-$2K.

I have $1100 in my 327 crank to get it down to 42lbs. The 302 crank is lighter to begin with, but to spin that rpm I would pendulum cut/bullnose and knife-edge/drill the rod journals and run a quality light steel I-beam rod and an OTS SRP piston. That = $$.

Not trying to rain on anyone's parade, but I can't tell you how many times I had guys come in wanting to build 302s that spin 8500rpm - which seems to be everyone's magic # for that combo, tho' really closer to 9-9500 is where that engine would work best based on rod/stroke ratios, etc.

Lastly, if you assume you want to drive this thing around town periodically, that cam won't make any real power below 6000rpm. My car is too obnoxious to drive with a big tappet cam that maxes the outputs between 5100-7300rpm. Below 3K it will lug the light 914 around the track no problem, but when it gets up to around 5K it takes off like a raped ape straight to 7300 when my shift light comes on.

FWIW.