Minimum spark plug gaps, Hi boost and VP fuel limits.....discuss

[fastblackracing]

Most of us know that when the boost goes up the plug gaps need to tighten up slightly, What is the minimum plug gap that can be used and not have issues driving and racing, I am talking about boost in the 35# ++ range. What are the boost limits when using vp c16 or c23 assuming the tune up is good and fuel system is up to task and charge air temps are good, this would be on a small 233 inch engine at 800 or so Fwhp. I will be reading the plugs but was curious of the fuel limits if you have pushed the limits. Time to let her eat.

 

[Mr.Spool]

I am talking about boost in the 35# ++ range.

a different world at this level,with the proper tune the hard parts become the failure point and to get to this level it goes beyond the plug gap.what exactly would you like to discuss as this thread could be a recipe for turbobuick disasters?

 

[Mr.Spool]

What are the boost limits when using vp c16 or c23

this depends on the combo as lots of things come into play like motor comp,heads,etc.

 

[bison]

Turbobitt ran 8's on the stock ignition. I don't know what the plug gap was but the engine was clean over 7000rpm and the car wasn't light at all. It was over 110lbs/min of air. He ran Sunoco maximal. I regularly run 32-33psi on 93/alky with the same coil and module he used since he switched to coil on plug and the gap is a little under .030". I'm at about 80lbs/min on an 8.3:1 engine. I have never seen the detonation limit on an engine using c16 or maximal or other brands high octane race fuel. The timing, CR, and cam will determine the cylinder pressure at/near tdc and that's what tears things up. Not boost. On a 9.5:1 233ci you can get over 90lbs/min with boost around 30psi still with a 3 bolt.


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[turbobitt]

Turbobitt ran 8's on the stock ignition. I don't know what the plug gap was but the engine was clean over 7000rpm and the car wasn't light at all. It was over 110lbs/min of air. He ran Sunoco maximal. I regularly run 32-33psi on 93/alky with the same coil and module he used since he switched to coil on plug and the gap is a little under .030". I'm at about 80lbs/min on an 8.3:1 engine. I have never seen the detonation limit on an engine using c16 or maximal or other brands high octane race fuel. The timing, CR, and cam will determine the cylinder pressure at/near tdc and that's what tears things up. Not boost. On a 9.5:1 233ci you can get over 90lbs/min with boost around 30psi still with a 3 bolt.


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Plug gap was whatever they were out of the box. No sense messing with the cut back electrode and trying to gap it. Plugs were AR473.
AG.

 

[fastblackracing]

Turbobitt ran 8's on the stock ignition. I don't know what the plug gap was but the engine was clean over 7000rpm and the car wasn't light at all. It was over 110lbs/min of air. He ran Sunoco maximal. I regularly run 32-33psi on 93/alky with the same coil and module he used since he switched to coil on plug and the gap is a little under .030". I'm at about 80lbs/min on an 8.3:1 engine. I have never seen the detonation limit on an engine using c16 or maximal or other brands high octane race fuel. The timing, CR, and cam will determine the cylinder pressure at/near tdc and that's what tears things up. Not boost. On a 9.5:1 233ci you can get over 90lbs/min with boost around 30psi still with a 3 bolt.


Sent from my iPhone using Tapatalk

Plug gap was whatever they were out of the box. No sense messing with the cut back electrode and trying to gap it. Plugs were AR473.
AG.

Thanks guys, I believe it to be 1 pound of air to equal 9 or 10 horse power, and since precision does not have or at least let it be public knowledge compressor maps I can not say what my 71 hpq compressor moves at 3 to 3 1/2 + to 1 pressure ratio....... I do know that on the dyno we made 680 rear wheel at 30# at 6200 and the pulls were clean to 6600. the converter seemed a little loose and working backwards is how the 800 flywheel guess is made. 680 + 18%. We are going to a track rental at the end of the month we will see how it goes, I will try to have it close before we get there and turn it up from there....... This is why I ask about the c16 limits and if anything better is needed. I will gap my next set of plugs to .025 and see how it drives.

 

[J-B Racing]

I heard people go as little as .028" when running around #35 boost.

 

[Mr.Spool]

At 35+psi run the gap down to 24 with no problems on the street

 

[fastblackracing]

Thanks guys, I believe it to be 1 pound of air to equal 9 or 10 horse power, and since precision does not have or at least let it be public knowledge compressor maps I can not say what my 71 hpq compressor moves at 3 to 3 1/2 + to 1 pressure ratio....... I do know that on the dyno we made 680 rear wheel at 30# at 6200 and the pulls were clean to 6600. the converter seemed a little loose and working backwards is how the 800 flywheel guess is made. 680 + 18%. We are going to a track rental at the end of the month we will see how it goes, I will try to have it close before we get there and turn it up from there....... This is why I ask about the c16 limits

At 35+psi run the gap down to 24 with no problems on the street

and if anything better is needed. I will gap my next set of plugs to .025 and see how it drives.

Thanks for the input JB and spool, thats inline with what I am thinking.

 

[J-B Racing]

No problem. Mine are always at .030"