Forced induct,Port & Polish w/ angle job, perf cams & retainers

triplebeam · #1 (**permalink**) 12-07-2003, 10:08 AM

Doing this to my engine will raise my compression, right? & then in the furture I want to add a supercharger or a turbo, Iam in danger to blow my engine doing a all motor setup then adding a forced induction????? let me know what u think

BMWGuy206 · #2 (**permalink**) 12-07-2003, 10:14 AM

Port and polish or any type of headwork isnt really worth it for a forced induction engine.

NA cams wont work well with a turbo setup.

Upgrading the valvetrain is a good idea but depends on how much power you plan on making.

Those mods will increase your effective compression ratio but not your static compression ratio. The only "mods" that do that are the headgasket, rods, crankshaft, pistons, and milling the head.

Try to avoid serious all motor mods, like cams, if you're going to do FI.

josh@werksgroup · #3 (**permalink**) 12-07-2003, 12:03 PM

Increasing the VE of any motor can help performance. There are a lot of tricks when preparing a cylinder head the will help with detonation. From ports to chamber to seats…. Not to mention by increasing the flow of the head you will decrease the charge pressure for a given mass air flow. This in turn lowers the charge temps lessening the chances of detonation. Camshafts can certainly help. Just depends on what you are doing with the car, what kind of power band you want. The factory M cams are reasonably aggressive so they are a good starting point.

dk_ · #4 (**permalink**) 12-07-2003, 06:25 PM

Quote:

Originally posted by BMWGuy206
Port and polish or any type of headwork isnt really worth it for a forced induction engine.

it's too bad you think that- your car could be making a lot more power.

BMWGuy206 · #5 (**permalink**) 12-07-2003, 08:27 PM

Wow.. that must be too bad for professional BMW engine builders and real owners having that type of mod and quoting that to me.

Maybe for NA setups it will work better but for forced induction I dont think its necessary because you're "Forcing" air into the chamber.

BTW a certain project car from European Car is actually going from a port and polish head to a factory one.

LordofMpower · #6 (**permalink**) 12-08-2003, 08:48 AM

the bottom line is anything that increase the VE of your motor increases its potential to make HP while these mods may make miniscule differences a properly tuned motor will make use of them whether NA or FI

josh@werksgroup · #7 (**permalink**) 12-08-2003, 08:59 AM

Jon,
I don't know you or your credentials. What I do know is European car is no source for technical information. I own every issue of the rag since it was VW&Porsche and I've watched it turn into a worthless pile of drivel with tech info that is designed to sway readers to the advertisers... In any case a properly ported head works with forced induction regardless of the fact you are "forcing" air in to the chamber. The merits of porting that I mentioned in my above post are very much true. Common thought is just crank up the boost and you’ll get more power anyway. Perhaps that’s true, it’ll cost you in the end though.

LordofMpower · #8 (**permalink**) 12-08-2003, 09:05 AM

well said !

freshstart · #9 (**permalink**) 12-22-2003, 03:25 PM

I may be able to shed a little light on this topic. Not that I'm in the engine building business or anything but I did just have a port and polish job on my factory head.
I honestly could not tell a hp difference from the seat of my pants but we can all be certain that as long as the job was done properly that there is indeed a hp increase, and the potential for more increases down the road because of the increased efficiency(sp?) of the motor.
To think that increasing the ve of a motor isn't really going to help just because it's forced induction exposes the knowledge and experience of whoever thinks that.
Just crank up the boost!lol

Barker

TYE · #10 (**permalink**) 12-22-2003, 04:47 PM

If you do decide to PnP the head, it a very mild pnp. Too much and low end torque decreases as certain turbo bmws have noticed and switched back to their stock heads. So, if it came down to it, there are other things you could do with the money for pnp rather then doing that. And for those that want to argue, two of the most reputable BMW Engine builders have told me that. A 5 angle race valve job would be beneficial. If you are going to turbo in the future, you should consider building a low compression turbo motor. You really need to decide what you want exactly, before just jumping in now, so yo ucan save yourself a lot of money and heartache.