All out performance bbc

[rustbucket79]

There is no reason for a tiny rod pin, if you’re looking for performance, you’re looking in the wrong area for (presumably) a grass roots race class.

Again, power/performance is found mostly above the short block. Find a head porter that knows what he’s doing with the heads you have to run, then once those are done a mold of the chamber can be made and sent off to the piston manufacturer so they can work their magic in terms of dome, ring pack, gas ports etc and fill the gap between the crank pin and piston.

What style and class of racing is this for?

[englertracing]

A 1.88 rod journal in a bbc sounds very flexy
Cylinderheads and camshafts are where power is made.

[FC-Pilot]

well i was thinking 13:1. 6.385 long rods.

anyone ever done a 1.88 rod journal in a bbc?

or low tension oil rings?

Both have been done successfully. If all out I would use much more compression. If a gm block must be used then use a bow tie block and start with a better foundation. Go with a larger bore which helps unshroud valves and then you can use a shorter stroke. As all have said, power is made above the short block. Larger cam core and .937 lifters (or larger) will help with valvetrain demands and then heads and induction to suit the power demands.

Post the class rules so we can help. As of right now we are playing darts in the dark.

Paul

[CamKing]

If they allow DLC coated lifters, we can make a tool steel cam that will handle a lot more spring pressure then the cast iron flat tappet cams.

[BillK]

Is this going to be a drag engine or long duration like road race or marine ??

[evilbanshee]

drag racing.

baically i have too come in at 440ci maxx. compression rule is maxed out at 13.5:1. not allowed too exceed .650 lift at the valve.

good idea on the billet cam core.

lets assume my heads and cam combo are maxed out too perfection.

thats why i was asking about a bottom end. ideal for max power.

[lefty o]

good windage control, vacuum pump, bored out to your max allowed inches.

[CamKing]

Have the lifter bores true'd, and if they allow larger diameter lifters, go with either .875" or .904" diameter.

[DeezNutz]

For all who claim there is no power to be made in the short block.... can you explain NHRA stock eliminator engines?
Truth is its there, just less gain for the dollar.

[evilbanshee]

Basically owning a engine dyno for about 5-6 years now, i have learned alot above the short block. I have tried dozens of cams. Heads flow great.

I just wanted some insight on what guys are using for exotic bottem end stuff. Cant run a vaccume pump.

I am currently using gapless top 043. gas ported bottom 043. 3mm standard tension.

Would .9mm and low tension oil rings be worth a look?

Also again the 1.88 journals if scat or someone will make me a crank.

I am currently making about 650hp.

I dont/ cant say whAT CLASS i am running sorry guys lol

[Old School]

Basically owning a engine dyno for about 5-6 years now, i have learned alot above the short block. I have tried dozens of cams. Heads flow great.

I just wanted some insight on what guys are using for exotic bottem end stuff. Cant run a vaccume pump.

I am currently using gapless top 043. gas ported bottom 043. 3mm standard tension.

Would .9mm and low tension oil rings be worth a look?

Also again the 1.88 journals if scat or someone will make me a crank.

I am currently making about 650hp.

I dont/ cant say whAT CLASS i am running sorry guys lol

Just curious, what et and mph are you running? How heavy is your car? Auto trans?

[KnightEngines]

Ditch the gapless top ring.
Steel 1mm low tension, vertical gas ports.
2nd Napier cut 1.2mm
Oil 3mm 12lb low tension.
That'll be worth a solid 8-10hp over your current ring pack.

Don't bother with Honda journals, pretty much nothing to be had there.

Largest bore you can go & match the stroke to get your cubes - the less stroke there is the less HP you're wasting pulling the rings up & down the bores.

Deep sump with full tray & big kick out, close fitting crank scraper.
0/30 oil.
Std vol oil pump, keep pressure at 50psi.

I beam rods - less windage than H beam.

Vac-u-pan if allowed, pulling from a valley breather.

Lightweight rotator doesn't hit the converter as hard on launch or gear changes, but accelerates faster in gear - juggling act, with a 3 speed you'd go heavier, 2 speed lighter.

[TMSJoe]

This class sounds NHRA stock.... ish. If so I think the rod dimensions are already dictated to you. BUT if you are allowed anything you want I would likely go with a +.400 rod. This would give you a 1.73 rod to stroke ratio which seems to be desired. I built a combo like this for my fathers car except we went with a 4.600 bore as there are no rules for us. I could have stuffed a longer rod in there which would have made for a lighter piston. But conversations with the piston guy and the cam guy directed me to the +.400. For RPM sake I would lighten the crank any way you can. If that means 1.888 rod pin, so be it.

In fairness, a target RPM range would be helpful since that flat tappet cam looks to be the biggest challenge here.

[evilbanshee]

now we are talking guys. good insights here.

aluminum rods worth anything? lightest crank i can get?

what rod? 6.185? 6.385? 6.535??

i use a turbo 400 trans. no brake allowed.

[evilbanshee]

also i currently go through the traps at 7500rpm.

78-8000 might need too happen on this new build. flat tappet cam is only allowed. the billet cam core is something i will look into.