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Re: How much turbo boost can a base, stock b-engine handle? Posted by Gary Stottler [Email] (#1463) [Profile/Gallery] (more from Gary Stottler) on Thu, 5 Apr 2012 05:51:53 In Reply to: How much turbo boost can a base, stock b-engine handle?, BAAB [Profile/Gallery] , Wed, 4 Apr 2012 21:18:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
BAAB,
As you add more boost, you run into two sets of problems:
1) Short-term pre-ignition which occurs when the air/fuel ignites due to the heat of compression in the cylinders before the spark plug fires. This can quickly melt pistons and cause catastrophic engine failure (literally in a matter of a few seconds). You might or might not hear "knock" or pinging when pre-ignition is occurring. This can be avoided at higher boost by richening the mixture (use a wide-range air-fuel ration in the exhaust and shoot for no more than 12 to 1 under boost), and by using water injection.
2) long-term engine wear due to temperature. Early (78-80) 8-valve engines had a different valve grind which was very prone to wear the valve seats and guides and result in burned exhaust valves - this would be accelerated by higher boost. The "bottom end" of the engine is pretty robust.
All that said, you could probably get away with 12psi on the 79 and avoid pre-ignition by using premium fuel (which was not available in 78-79, that's one reason the CR was so low) and an 82 degree thermostat. However, I would use an air-fuel sensor. If you get into non-stock enrichment and water injection you can probably do 15psi or more.
A lot of early cars ended up with blown engines because people just started cranking up the boost. Goes real good (for a little while, anyway)!
Good Luck,
Gary
posted by 198.208.15...
_______________________________________ Gary Stottler
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