Author Topic: compression with higher dosage of nitro  (Read 1405 times)

Offline wideopen231

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compression with higher dosage of nitro
« on: July 12, 2021, 03:13:19 PM »
 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.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline hemidakota

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Re: compression with higher dosage of nitro
« Reply #1 on: July 13, 2021, 04:34:40 AM »
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
If it jams force it, if it breaks it needed replaced anyways

Offline Curly1

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Re: compression with higher dosage of nitro
« Reply #2 on: July 13, 2021, 07:32:08 PM »
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.

Offline msundstrom

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Re: compression with higher dosage of nitro
« Reply #3 on: July 13, 2021, 10:13:55 PM »
I run 11.7:1 in a BBC (different animal than a hemi) but this seems to work for me at mid 40ís%. 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 etís 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, donít break stuff and I make plenty of power.

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #4 on: July 15, 2021, 07:23:38 PM »
 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
« Last Edit: July 15, 2021, 07:28:16 PM by wideopen231 »
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #5 on: August 08, 2021, 08:35:59 PM »
After this weekend with A/Fuel TA/D it is going to get higher on both.  Running 15.5:1 with 95% is just too xxxx much fun.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline hemidakota

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Re: compression with higher dosage of nitro
« Reply #6 on: August 08, 2021, 09:10:47 PM »
Love it, Intake Valves kissing the pistons in every hole...
If it jams force it, if it breaks it needed replaced anyways

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #7 on: August 09, 2021, 06:37:33 PM »
no intake kissing but exhaust makes out pretty good. Remember the heads are fat head style with lot smaller chamber than std Hemi. Easier to get high compression. Owner said Prock spent about 6 hours one day profiling cams and pistons to get even  more compression. Two hours chatting off and on with Procl might be coolest part of weekend.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #8 on: October 17, 2021, 08:20:09 PM »
Love it, Intake Valves kissing the pistons in every hole...

At least if they just kissing they are little ways away from getting-  -----d up.LOl Had quite a few setups where they marked top of pistons a tiny bit.Polished them out and sent them back again.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #9 on: October 17, 2021, 08:22:51 PM »
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.

100% positive we are running that high with 94.3 t0 94.8 in tank. What amazed me was if run lean it will drop cylinders.nothing else happens.We have to roll some bearing in her,but thats about 15 minutes.
« Last Edit: October 23, 2021, 09:19:06 AM by wideopen231 »
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline msundstrom

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Re: compression with higher dosage of nitro
« Reply #10 on: October 17, 2021, 09:16:45 PM »
Does it drop holes because the ground straps get burned off?

Offline Supercat

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Re: compression with higher dosage of nitro
« Reply #11 on: October 18, 2021, 04:45:29 AM »
Our new 560" is 14.5 to 1 NA looking forward to what amount of Nitro it likes or doesn't like I guess.

Offline msundstrom

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Re: compression with higher dosage of nitro
« Reply #12 on: October 18, 2021, 10:15:34 AM »
I donít think the Intake valve closing point should be left out of the static compression conversation.

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #13 on: October 18, 2021, 12:40:11 PM »
Our new 560" is 14.5 to 1 NA looking forward to what amount of Nitro it likes or doesn't like I guess.

Nope. No ground strap on these plugs. They are NGK bUE. Prock had avideo of them on JFR test stand and they looked like football fiel lights next to 75watt buld cmpared to ngk 1o plugs. Dropping cylin der because Anthony set BDK for wrong setting and car was too lean.Didn't burn anything. We figure to run BK pressure back up for extended time on topend. Been told its not lean but all indication say other wise. So if we keep pressure up and  then pull fuel on top and cylin der either lives longer or all the way we will know our idea is working. We have cpl old run data logs that Prock made up and had some low 5.20 runs,going back to those as much as weather and track will allow.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline wideopen231

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Re: compression with higher dosage of nitro
« Reply #14 on: October 18, 2021, 12:53:31 PM »
I donít think the Intake valve closing point should be left out of the static compression conversation.

Agree 1000%. To prove point.Knowing cam in my car is TOO big duration wise. I advanced it and ran CC check. 4* gasined 20 lbs,8* gained another 20 and last 2* gained 15 more lbs. es I checked piston to valve and had a ton left I need more material in valve pockets. I figure there is about a full point to be gained and or more lift. My plan is to get compression as high as can with thin gaskets and if need less compression I can add gasket..Loty easier than trying to build it. 2.45 cc's per .010 of gasket so going from .040 to .09 or .100 meas 12 plus cc change and that comes out to almost 2:1 and puts me same place I am at right now but with .125 larger bore with new piston and rings I ordered.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot