Anyone have info on head work?

[hansmaester]

Has anyone performed headwork on a S52US head? Ifso, how much improvements did it gain?

I have just purchased a dead cracked head ('95 325) that I am going to cut apart, so I know how much material can be removed. I understand the only difference between 325 head and M3 head is some additional machining work.

Next week I am purchasing an additional 325 head that I am doing the actual work on. Are larger valves possible in these heads?

Does anyone have pictures of stock and modified ports on any of these motors? Does anyone have stock flow patterns from a flow bench.

My plan is to get the most efficient head possible :) I will be recording flow patterns on a flow bench before and after. However, it will be on a stock 2.5L head.

Anyone have any recomendations or additional data?
Thanks in advance

[hansmaester]

Also, where can I get a descent valve spring compressor from and valve stem oil seal removal tool?
Thanks

[943184dr]

someone please correct me if i'm wrong but aren't the m52 and s52 head the same where as the m50 and s50 the same. not the m50 and s52 in this case? i sure hope i'm wrong. but given if i am i could see 15hp with some major machine work. all though you are F/I so i could see a bit more then that but you might loose a bit of low end torque unless you are running a good amount of boost.


Tom

[patrick S]

maybe us models have same heads but euro ones definately not

[VPD]

Has anyone performed headwork on a S52US head? Ifso, how much improvements did it gain?

I have just purchased a dead cracked head ('95 325) that I am going to cut apart, so I know how much material can be removed. I understand the only difference between 325 head and M3 head is some additional machining work.

Next week I am purchasing an additional 325 head that I am doing the actual work on. Are larger valves possible in these heads?

Does anyone have pictures of stock and modified ports on any of these motors? Does anyone have stock flow patterns from a flow bench.

My plan is to get the most efficient head possible :) I will be recording flow patterns on a flow bench before and after. However, it will be on a stock 2.5L head.

Anyone have any recomendations or additional data?
Thanks in advance

Improvements can be made to the stock ports, however this is best left to someone who has either done it before or has access to a airflow bench. In some cases bigger ports are not necessarily better and can actually hinder the airflow. The biggest and simplest gains can be made by improving the angle transition on the valve/valve seat. Flow increases can also be made by unshrouding the intake valve in the combustion chamber area. A stock port should flow around 200 cfm at full valve lift. You can get approximately 10-15% more airflow with a good 3 angle valve job and mild porting in the proper areas.

[nickdrivesm3]

your best bet could be to find a local machinist and ask him. If you know someone that could refer you, look for someone who does Drag heads so that they can bench flow it.

[hansmaester]

Yes, it will be done with aid of a flow bench. I have a sacrificial head that is being cut apart. But now I need to find a good head. Anyone have any ideas?

[ICS Performance]

Yes, it will be done with aid of a flow bench. I have a sacrificial head that is being cut apart. But now I need to find a good head. Anyone have any ideas?
Ill check I may have an extra cylinder head, ill be gladly to help you. :)

[hansmaester]

Thanks a bunch for looking!

[Turbo331is]

There are several companies that make oversized valves. Ferrea makes 1mm oversized valves, as well as VAC Motorsports, among others. 1mm is about the max you can reseat a valve. More than that and you are pushing structural limits. BMW heads, M50-S52 all come with a 3-angle valve job from the factory. The only improvements you are going to see are with a 5-angle, a mild port and polish, and a raised limiter. The valve springs on the S50/2 are pretty beefy from the factory, capable of 8000 or so rpms, which is more than you will see with your hydraulic lifters. Your hydraulic lifters will begin to fail at around 7700(You can thank the great engineers at BMW for this one). Once they fail, you are destine to float every vavle. Back to the subject, there are three companies I know of that make an off the shelf double valve spring setup. Ferrea, BMP Design, and VAC Motorsports all sell double valve spring setups. Pricing ranges from $400-$1200. Once you get your new vavles, and valve springs, you will notice the difference in weight of the lighter weight valves. To properly setup the engine, it is my advice to run titanium valve retainers. While 90% of this board will tell you they are garbage, myself and several others can vouch for the mileage put on the head, as well as the difference. The rotating mass up top is now reduced, but then you have to focus on your bottom end. There are several ways to reduce the mass down low. Your 3.2L crank is some 10lbs lighter than a 3.0L crank, so right there you are one step head. A properly built engine is a square engine, with all of its weights balanced, I.E. Balanced and Blueprinted. Reducing bottom end rotating mass will yeild you good gains, improved revving and power band(Supercharger), and a much free'er revving engine. Most people when building an engine just buy off the shelf JE, Wiseco, CP pistons, but don't take the time to balance everything. It wasn't until I was working that I realized this principle. A machine shop will balance your pistons, rods, and crank within 5 grams. 90% of machine shops will balance these buy adding weights to the pistons, rods, or crank. What most people fail to realize is that your new pistons are quite a bit lighter than you previous pistons...like this: Stock BMW 3.2L pistons mass at 600g. Your new pistons are 582 grams. What most machine shops will do is add weights to the pistons to get the piston/crank balanced, but then you just went against the reason for buying lighter forged pistons. Its quite simple, but most machine shops are skilled enough, so they just add weights to the pistons rather than machining the crankshaft. Once lighter pistons are bought, I would highly reccommend having your crank balanced via knife edging. You have to be careful, and make sure your machinest knows the mass of your pistons before he/she cuts excessive amounts off of your crank. Now everything is balanced there, but if you want to see greater power, here comes the rods. Rods are typical heavy and kill the rotating mass, but hey its needed to stop the rods from bending. But then comes in forged h-beam, or upgraded forged I-beam rods. You will knock off a bit of rotating mass with those, but again your bottom end will have to be rebalanced. If money is no object, Titanium rods are the way to go. The knock off some 2lbs of rotating mass, and are just a dream come true, but expect to pay upwards of $1000 a rod, or $6000 bucks.

The point of everything was to make you understand how deep building an engine goes, and what you have to be focused on. There is a lot more indepth things to talk about, but you just have to be careful when touching your top end. Nothing about building an engine is cheap, so just take it for what it is.

Any more questions about Ti retainers, or double valve springs, or hardened keepers, just ask!

Wes