JRW'S 91 318is turbo build

[wazzu70]

Chances are really good you will screw up DIY porting more than helping. The BMW heads are usually pretty good from the factory!

If you want to do something, blending the pressed in valve seat to the head casting is where most of the gains will come from in a majority of port jobs. You will see there is a slight lip in that area, so smoothing that out is helpful

Blending the manifold to the head port would be something you can do as well.

[jrw21]

Yeah, I decided not to touch it. I talked to the head builder at the machine shop today and he said he would take a look at it and do a good valve job on it too.

So here are the parts all ready to go:

Supertech Valve springs
Supertech Titanium valve retainers and seats
Supertech 6mm Valves
6mm oem valve guides
Supertech 6mm seals
VW INA hydraulic lifters

[jrw21]

Started tearing out the rest of the underside tonight.

[benz-tech]

If you decide to blend  the manifold, I very very highly recommend the honeycomb shaped tool in post number 5 of this thread- last picture, all the way on the left. I have ruined a few ports in my day until a pro told me that I absolutely must buy this one tool. It never digs into the sides since its always on the arc of the bit and it will make you feel like a pro. You could very easily not sand after using this tool but you really should do some minimal finishing. I think the one I have is even slightly less aggressive also.
Here's the thread:
http://sr20nation.com/ga16forum/showthread.php?1014-Cylinder-Head-Porting
similar to this one but longer is easier to use:
http://www.cylinderheadsupply.com/ac6312002.html
and nice to finish off with these:
http://www.cylinderheadsupply.com/2661.html

[jrw21]

On a street motor 135mm vs 140mm rods wont make a huge difference. Longer is better, but if you are trying to use OE pistons, just use the rods that are the best match.

Shaving the piston crowns that much could definitely cause issues. The piston crowns on turbo motors are usually thicker than atmospheric engines due to the higher temperatures and combustion pressures.

Really, custom pistons are worth the cost for this. You get the exact CR you want, the ring land spacing you want, crown thickness you want, ect! Small price for many benefits!

You talked me into it. I have decided to ditch the s52 pistons and go the custom route. Now, I just need to dial in what CR to order pistons.. somewhere between 8.3 to 8.9 is what I am leaning towards. 8.9:1 is what I would like to run just concerned about detonation at the higher CR.  Any thoughts guys?

[romkasponka]

Why you want so low compression ratio? All my friends which are building dozen turbo engines per year are not going lower than 10:1 these days. Check that compression ratio standart cars have these days.
http://www.youtube.com/watch?v=sptsXGSRkDY
He runs on ron 98 fuel also but with not so agressive map and lower boost.

[wazzu70]

8.9:1 is where I would shoot for in that range. As mentioned, no real need to go lower than that.

[jrw21]

Interesting to know. I always thought it was best to stay in the 8's when in high boost. Planning on running 93 octane, and 20-25psi (now that I am going forged pistons). I want to be somewhat conservative so I wouldn't feel comfortable running 10:1. So, maybe go 9.5:1?

[romkasponka]

Lots of people go with low compression ratio because there is no good tuner available and they afraid of their inability to make proper map. But in this case you will loose some spool up time, power, thermal efficiency.

In case you can get fuel with ethanol (E85) you can go even with higher compression ration.

[jrw21]

Lots of people go with low compression ratio because there is no good tuner available and they afraid of their inability to make proper map. But in this case you will loose some spool up time, power, thermal efficiency.

In case you can get fuel with ethanol (E85) you can go even with higher compression ration.

e85 is not common in my general area. But, it is very common about a 40min drive from me in each direction. Honestly, I never thought about going with e85 I may have to check into that. But, not sure if that is something I want to limit my car to.

 

[jrw21]

Todays progress:

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Had to stop somewhat early, interior work kills my back! Whiskey and Ibuprofen to make the pain go away.

[wazzu70]

Looks like the inside of my car not too long ago! It was a relief when it all went back together.

Id stick with 9:1 compression if you want to stay on pump gas just to be safe.

[jrw21]

Yeah, its a mess right now! Today I am going to sort the wires.  I dumped that huge HVAC unit and associated pieces, speakers, radio, ABS, SRS, and any other meaningless pieces. So, that should make putting things back together a bit easier.

I need to find new carpet as mine is TRASH!

Also, it appears my heater core was leaking into the drivers side floor pan as the carpet was a bit wet by the pedals. The car has been in storage for about 5 or 6 months so no rain water... Oh, and no I wasn't going to smell it to find out if it was radiator fluid 23 years of nastiness on that carpet.

[wazzu70]

Funny, I did the same thing. I put the HVAC back in though, but removed the heater core so its just a fan now. My heater core was also leaking from the valve into the drivers floor

Its amazing how much room there is without all the extra modules. I removed all the excess wiring too!

[jrw21]

Its hard to believe that there are this many wires in a car that's this old. There a about 4 dozen wires going into my door and all I have is window go up and window go down and power mirror.  I took all the tape off the wires while the loom was still in the car and chased wires for hours cutting out "unnecessary" pieces. Ok, jokes aside. I have decided the only amenity I am keeping are the power windows!  I can't even begin to imagine what it would look like doing this to a fully loaded vehicle these days.

No progress today as its literally 0 degrees outside and there is apparently a shortage in propane. We are being charged between 3.5 and 4.5$ a gallon for propane right now, if you can even get it... so going to "try" to limit my shop time this week.

But, I did order pistons!! Wiseco 86.5mm 9:1!