Adviced on engine combo

Advice on engine combo

Hello All

I'm having a hemi built at the moment.

It is a build of mainly old fuel parts.

here is what we are planing to use

My old mag buzzard alcohol injector.
TFX billet block.
AJPE stage II Fuel heads
New fuel pump and system.
MSD 44 single magneto.
SSI prepped fuel blower.
billet low run fuel crank, that has been checked.

This engine is meant for my Top sportsman / pro street '68 camaro, behind a powergilde transmisson, or if needed be a BJ converter drive. I used to run a 555 blown bbc in it.

I am not looking to rotate the earth or anything. just to have some fun with a reliable engine.

My main question about this is whether to have the sleeves bored out to make this a 526 or keep it at 500.

I know it is not really about those 26 inches, my main concern is the compression ratio. With fuel rods and pistons we can get it up to around 10:1, If we use the long rods combined with the high pistons and a skinny head gasket
If i opted for boring the sleeves we can get any compression we want as i would have to get alcohol rods and pistons.
It is my understanding that 10:1 is on the lowside of what is workable in an alcohol engine. My old BBC had 11,5:1

As for overdrive on the blower, well somewhere around 30% - 40%.

So will 10:1 do? or will it just lay over? I would really like to stay with the fuel parts as that will ease my access to spares alot.

Sorry for the long post, and thank you Will for a super site

Thanks

Sune Larsen from Denmark

 

i have a new set of alky 4.28 pistons (10) and a very nice set of used rods i will make some one a hell of a deal

 

If you can get a true 10:1 compression ratio and already have access to the parts, run it. Yes, it is a little on the low side, but you'll have more of a tuning cushion with boost and timing without hurting anything, since you say your objective is to have some fun and reliabilty. As always, you'll eventually want to go faster, you can step the compression up then. Years ago, I built a 9:1 blown gas Hemi for a dragboat, changed over to alky with timing and blower boost changes and had fun with it for two years in an index class changing plugs and setting valves only. Its all about what you want to do with it and determining what it takes to get there. Good luck with it.

 

Depends how fast you want to go. 10:1 should provide reliability, as you said, and if you get the tuneup right, should put you in the 7 second range (don't know much about door cars, but a dragster would run low 7's or high 6's). Be careful about boring the block out too much, the blower, especially a standard fuel blower, will have trouble filling the hole if you make it larger. Bigger cubic inches is not necessarily better.

 

combo

Just remember those fuel pins, rods, and pistons are really heavy. example pins 300 + gms. pistons 800+ gms. you get the idea. By all means run them just beware of rpm flywheel speed etc. Keep us posted and have lots of fun. Alot of us forget the fun factor after awhile. Don

 

I agree with everything on this post, 10:1 comp is a little low for big hp but the tuning window should be wide and easy to learn.

Run it for a year or so maybe and if its still not impressive enough, then get some compression in it.

 

Thank you very much for your replies.

After your comments I have to say i am thinking about just doing it right from the get go instead of messing about with the fuel rods and pistons.

What would be a a good soild workable compression ratio to shot for, I am still looking for a setup that is low maintains, but wont be a turtle either?

The fuel rods and pistons, are not free to me they are just available. so instead of spend $ on the wrong stuff i would rather buy the right stuff from the get go.

This engine will never see the amount of runs that you guys put on your stuff in the states.

@ ken stiko

Is the blower concern really an issue ? with only 26 more inches?

thanks

Sune Larsen

 

If you are running full out, trying to run your best numbers all the time, and you were to bore out the cylinders and use the same blower, I believe you would slow down. If you are running a conservative combination, and have lots of room to tune, you would be able to compensate.

We once bored out our TAFC motor to increase the size from 511 to 526 cubic inches with a roots blower, lost almost a tenth and couldn't get it back.

 

I assume that you didn't change the camshaft with the increase in displacement? Gives new meaning to the phrase 'no replacement for displacement.'

 

Nope, just used the standard R296-500 cam that everyone else uses. Don't have the time or money to experiment.