Technical > Spud Miller's Cave

compression with higher dosage of nitro

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wideopen231:
 Ordering ne pistons for  second motor. Its basically new TFX92 block and KB crank with 4.375  and and new GRP rods. All good stuff. Going to order pistons with more compression and thinking that with this set up I can run about as much compression I want . I know the A/fuel car I work on runs 15:1 and all the load they allow.LOL

Any reason not to go ahead and get some 14 or 15:1 pistons even if I figure to run a bigger load say 50& plus before I quit adding,yea probably not quitting till I max it out. I know converter will limit amount of fuel I can get it to burn and going to need a new one or a bolt together so I can change stall as I add nitro.

  How much does extra compression change the tuning window? Yes I always buy 10 set pistons, in case of.

hemidakota:
There is a local clutch guy that runs an afuel car, compression is not an issue from what they say...Love to learn about all this stuff

Curly1:
Are you sure they are running that much Nitro with 15 to 1?  From my experience it detonates bad with high compression. I would think with 50% or more they would be 11 or less to 1.

msundstrom:
I run 11.7:1 in a BBC (different animal than a hemi) but this seems to work for me at mid 40’s%. I used to run 12.45:1 and always had loose flex plate to crank bolts and Valve cover bolts. Tuning window was very small. Now it is very forgiving and no bolt issues and et’s are way better. I think Gene Adams spoke about a max of 11:1 for NA nitro in a hemi but that was a while ago. I believe Spud was around 12:1 in his SBC at 100%. My maintenance and cost is low, don’t break stuff and I make plenty of power.

wideopen231:
 Talking with guy who owned car before Larry bought it 15:1 with 95% load is  normal TA/D A fuel setup.which is reason you have to be so careful about making sure cylinders are open(both plugs out ) and lines are loose before rotating motor once you get back from run. Screw up and its bad day in you neighbor hood.  Most already know that nitro is hard to lite off but easy to make explode if compressed. Harder to detonate when have huge ass pump pumping butt load of it thru engine.Now that is big show a/fuel not nostalgia with huge pump.

Thinking about sending one of my old 1200's off and havng restrictor added to reduce it to 11.6 gpm. Kind of like A/fuel nostalgia does. I know I can not burn as much fuel with TQ converter as a clutch car can due to lack of pull against motor. Also know converter will have to be changed or totally different converter(best option) all together, Figure 3.20or 2.90 gear with different converter will still give me lots of lug on motor. Not something I would do with motor in car,but it just so happens I have another short block same components  except bigger that I could build for large dosage runs. Got to get this deal worked out first,but options are nice. As long as I don't airyated block I am fine with killing few soliders or bearings. Always buy ten set pistons and rings,plus have about 20 sets bearing and cpl sleeves upper rod bearings left over from out old deal. Never been scared to hurt parts as long as block and crank are not included in destruction.Oh yea and driver.LMAO

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