im about to get boost, but i heard that if you were boosting on the highway for extended amounts of time in boost, then its bad for your motor.. is this true?? if so would a supercharger on the highway for extended amounts of time bad since the boost is from the start?? or would it be the same as turbo and just stay under low rpms?? also...would a supercharger be able to keep up topend witha turbo??? thanks


tony.

ps. sorry if this is the wrong spot to post...and if its a bad question..


Modified by BoostedEMone at 11:10 AM 12/8/2005

 

Eh... as far as Supercharging for long periods vs Turbocharging for long periods, it's all the same. It's all forced induction. Mostly it depends on how much youre boosting, but it shouldn't be a problem unless you're redlining it in every gear down the high-way. Granted with a lapse in tuning or a probable issue here or there could be the only problems to a FI setup done well. So there shouldn't be much of a problem if you did everything in a well fashioned manner.

 

mm well i was only planning on boosting at 7 on a stock motor w/ tune for now. but later i want to go pretty far.... i have a si and i know it has pretty short gears...when i go out of town im pretty far up there in the rpms... from what i heard you can stay out of boost with turbo and still be ok... where as supercharger has boost from low end....

 

it all depends on how you are driving. the turbo won't spool unless it is under load, so just crusing on the highway you will be out of boost, thus no worries.

 

Look at it in terms of this:

A normally aspirrated engine runs on it's normal mixture of fuel and oxygen. The only two things needed for combustion(besides catalyst). Fuel can easily be increased with fuel pump and injectors. The oxygen however will remain the same unless you get an intake(doesn't help a ton) or force air into the motor. Therefore forced induction comes to be. More(forced) air into the to mix with more fuel equals more power. And thus forced induction works.

Now how does this differ from NA? It is just more power moving through the cylenders, and with the stock internals it causes a problem without good tuning.

It's not so much the gearing that's going to be in question here, moreso the tuning. Granted a well tuned car can't peak and hold at redline all day, something will faulter here and there. However it can safely move throughout the powerband without any risk what so ever. The question is moreso on your engine than the gearing. Can your engine propprely hand boost through the RPM's that your tranny allows for your engine.

 

When you are under boost, your PCV doesn't open, right? So you therefore have gases around the crank which would usually be vented and is bad for the engine (which is why a catchcan is used on most turbo applications correct?).

So by this logic, being under boost for a looong period of time would be detrimental, but if you aren't under load, you won't build boost.

If I am wrong here, I would appreciate the correction so I can learn more

 

well....as long as you're not boosting hardcore, you'll be ok. i made a 3 hour trip down to salem, oregon last weekend. and my car is ok. i was going around 70mph no boost though

 

Motor gets heat soaked over time on long highway boost pulls, having water injection can help this.

 

thank you everyone

 

the PCV system is your biggest concern here because the PCV valve is a one way valve and when u boost this system it keeps the one way valve closed and then crankcase pressure begins to build which is why extended periods of boost on the highway is bad. When u boost the crankcase oil can get pass the rings and cause detination and fry rings, crack pistons, or broken ring lands. Get a crankcase ventalation system and you will be much safer for extended boost situations.

 

i drove 6 hours at 70-100 mphs the entire time in and out of boost and my car is fine , watch your egts and water temp

 

Its fine to boost on the highway you will not have you foot down for long as you bypass the speed limit/safe driving speed in no time at all. In my teg I drive down to our holiday home its about 300kms I drive spiritedly the whole way most of its highway miles, then some nice twisty mountain roads. Never had a problem you need a good tune for sure that is all.