Question about Boosting

[BlackbirdOfPrey]

I just have sort of a general question about boost in general. If you look at our cars most of us start at 10 Psi of boost and usually have more, with small turbos, but on a honda or some other car, they may only run 7-8psi even with larger turbos. what is the main factor in determining this? I know airflow is part of this, but if you go with a large turbo on our cars they usually go 20Psi and are about the same as the 7-8 Psi boosted honda. Or another example is a 420A motor running far less boost than the 4g63 yet both having 16Gs. Is it based on internals, displacement, reliability, or what? Its something I've always wondered.

 

[trbotaln]

they only run low boost becuase thats all the motor can take with stock internals. If your car comes with a turbo then your motor is beefed up from the start and you could run more boost. Also when you turbo a N/A car they usually have too much compression to reliably boost a lot on the motor.

 

[BlackbirdOfPrey]

Ok let me make sure I have this straight. Lower boosted vehicles usually have weaker internals that can't take the pressure. And higher compression = lower boost? Does this also apply to supercharged vehicles as well (usually don't run more than 6 psi or so)? THanks for clearing that up.

 

[iowaboostin]

Ok let me make sure I have this straight. Lower boosted vehicles usually have weaker internals that can't take the pressure. And higher compression = lower boost? Does this also apply to supercharged vehicles as well (usually don't run more than 6 psi or so)? THanks for clearing that up.

I would think it'd be the same for SC vehicles, it might not be as drastic as turbocharging a N/A engine, but to a point, you wouldn't want to throw a huge SC on a Ford Tempo and run it to its max.

 

[BlackbirdOfPrey]

THanks for the info guys. I like to know why things are and what I'm doing to a car before I do it, that way when things blow up (and they will on a DSM) I know why and how to fix it. It was just one of those things I had wondered about for some time.

 

[Catbox_95]

Yeah, it's all about compression - the more you have, the less you can safely boost. It is the same for both superchargers and turbos. Even nitrous too.

 

[xcelr8n]

THanks for the info guys. I like to know why things are and what I'm doing to a car before I do it, that way when things blow up (and they will on a DSM) I know why and how to fix it. It was just one of those things I had wondered about for some time.

Its good to know how things work before you work on them yourself true, but just becuase its a DSM doesnt mean its gonna blow up, in fact these engines and the stock 14b are very strong from the factory. As long as you dont push the car beyond its means in terms of to much boost, or a overly lean condition you should do just fine.

 

[99gst_racer]

Ok let me make sure I have this straight. Lower boosted vehicles usually have weaker internals that can't take the pressure. And higher compression = lower boost? Does this also apply to supercharged vehicles as well (usually don't run more than 6 psi or so)? THanks for clearing that up.

Yeah, you have it right. Even supercharged vehicles run low boost (ei. 6 lbs. or so).
Many N/A vehicles came with high compression, because they were not designed to be used with forced induction. Our cars, on the other hand, were designed to be turbo'd and thats why our compression is lower than most N/A's. N/A vehicles have weaker internals because they weren't designed to be used with the added pressure of a turbo or supercharger.