Jump to content
FB73tii

Newer head casting preferred for M10 race engine?

13 posts / 10832 viewsLast Reply

Recommended Posts

Any preference on the age/mileage of heads that will be ported for a race engine build? I know to stay away from thermal reactor heads, but other than that, if the head is in very good shape (enough thickness, no cracks, passes pressure test, water passages not thinned out by corrosion), is there any concern about using an older head? Or should I look for an NOS head and/or one with a later casting date?

The reason I ask is that I already have a 1969 casting 121ti head and a 1973 casting E12 head. On one hand I might send the candidate head to a pro for the full valve/porting job, and on the other hand I am considering having a shop do a good multi-angle valve job and throat cut, and then do some mild valve-pocket porting and intake/exhaust port-matching myself.

I have not done porting before but am interested to learn. Perhaps this argues for using one of my old heads in case I make a mistake. I am re-reading "How to build, modify and power tune cylinder heads" (Burgess & Golan, 2008), and will read David Vizard's new book, "How to port & flow test cylinder heads" (2012).

BTW, the build will be 2.0L, 45DCOE, Schrick 316, +1mm valves and roughly 11.5:1 compression. All necessary bits will be used to make sure it holds together.

Thanks, Fred '74tii & '69GT3

Share this post


Link to post
Share on other sites

when it comes to aluminum cylinder heads (no matter what the make of car) new is always (always) better than used (you are probably saying wtf, no kidding), I sold my Schnitzer head which was new and decided to refurb my used head which is very good. Prior to that a 3d party engine guru dude and I had this same conversation and that is exactly what he told me - I didn't listen. My opinion is that if the head hasn't been cut too many times and is tested etc., you are porbably OK. If I were going to sink money into porting, changing the CC etc., I would go for the newest casting I could afford that was in the best shape. Less heat cycles = better. Just me. Good luck with your project.

www.alpinabmw2002.com

Share this post


Link to post
Share on other sites

Unless you have experience on a flow bench and have one, don't port your own heads. Just shine them up and make yourself feel happy doing like a very minor adjustments. Porting them isn't easy. Vizards book is a good start but you'll learn alot on your first five heads.

Share this post


Link to post
Share on other sites

To: FB'73Tii,

If you haven't sawed thru your cylinder head yet, maybe these pics will be of interest to you........................and your machinist.

Might help you before you start "porting & polishing". Give you some ideas about "where and how much".

Good Luck.

mac.

post-16466-13667666116668_thumb.jpg

post-16466-1366766611754_thumb.jpg

Share this post


Link to post
Share on other sites

Fred,

The advantages of using a new head casting are two fold.

1. Less heat cycles with a new casting (as Mark stated).

2. When the new heads were cast, the exhaust stud holes are closed off to the inside. This is different than the original heads that would eventually allow engine oil to weep from the stud/studs.

Our rebuilds these days and for quite some time use only the new castings or new heads. If we get lucky and have a good clean original casting the machine shop welds the holes closed.

HTH

R

Share this post


Link to post
Share on other sites

Thanks to all for your input. Mark--sage advice, for sure. Kris--I figure I have 15-20 years left to learn new skills and put them to use on the track. I'll need to look carefully at whether I want to put in the time to learn how to port heads correctly. Mac--thanks for the cross-section photos, they are great. I do have a junk head I could have sectioned so I could really understand the port profiles. Rob--what do you consider as new castings? The E30 318i head? What are the latest casting dates you have seen on the earlier 121 and E12 heads?

The following M10 cylinder heads appear to still be available through BMW. The list price on all is $1107.17 and the best price I found (same for each type) is $830.38 at Husker BMW. If I got any of the part numbers or info below wrong please correct me. I did not come across a part number for the 121TI head.

2002 121 Cylinder head

11120721008 (01/1968 - 08/1973)

2002 E12 Cylinder head

11129061432 (04/1971 - 12/1975)

E21 320i M10 Cylinder heads

11121262178 (to 07/1979)......(2.0L)

11121268720 (from 07/1979)....(1.8L)

E30 318i M10 Cylinder head

11121273918 (07/1984 - 04/1991)....(1.8L)

Is it correct that the E21 320i heads have injector holes that need to be plugged and the E30 318i heads do not have these holes?

Fred '74tii & '69GT3

Share this post


Link to post
Share on other sites

I have 79' 121t head left for porting and tuning under alpina standards 48/39 valves. Head is from 79' 2002ti that was built by BMW worker for itself. He made 3 2002ti's, and when i got mine side by side with 69' 121ti there was no difference in any other way just the material was more rough on 69, probably different mixture of aluminium, first heads were much more likely to make a cracks than later e21 and e30.

Share this post


Link to post
Share on other sites
Thanks to all for your input. Mark--sage advice, for sure. Kris--I figure I have 15-20 years left to learn new skills and put them to use on the track. I'll need to look carefully at whether I want to put in the time to learn how to port heads correctly. Mac--thanks for the cross-section photos, they are great. I do have a junk head I could have sectioned so I could really understand the port profiles. Rob--what do you consider as new castings? The E30 318i head? What are the latest casting dates you have seen on the earlier 121 and E12 heads?

The following M10 cylinder heads appear to still be available through BMW. The list price on all is $1107.17 and the best price I found (same for each type) is $830.38 at Husker BMW. If I got any of the part numbers or info below wrong please correct me. I did not come across a part number for the 121TI head.

2002 121 Cylinder head

11120721008 (01/1968 - 08/1973)

2002 E12 Cylinder head

11129061432 (04/1971 - 12/1975)

E21 320i M10 Cylinder heads

11121262178 (to 07/1979)......(2.0L)

11121268720 (from 07/1979)....(1.8L)

E30 318i M10 Cylinder head

11121273918 (07/1984 - 04/1991)....(1.8L)

Is it correct that the E21 320i heads have injector holes that need to be plugged and the E30 318i heads do not have these holes?

Fred '74tii & '69GT3

Fred,

Will go over the numbers and fill any blanks. Busy Friday here - will post after checking with the details. Thanks for making it easy. 8^)

R

Share this post


Link to post
Share on other sites

Most would choose a 121 head over an E12 one as it has a smaller combustion chamber and better squish areas. If you are putting 48mm inlets and 39mm exhaust valves in larger seats will have to be fitted anyway.

I have built up race style engines with both heads with the 121 having some gains in power over the E12, as the piston did not require as large a lump on top which inhibits the flame front somewhat.

Share this post


Link to post
Share on other sites
Thanks to all for your input. Mark--sage advice, for sure. Kris--I figure I have 15-20 years left to learn new skills and put them to use on the track. I'll need to look carefully at whether I want to put in the time to learn how to port heads correctly. Mac--thanks for the cross-section photos, they are great. I do have a junk head I could have sectioned so I could really understand the port profiles. Rob--what do you consider as new castings? The E30 318i head? What are the latest casting dates you have seen on the earlier 121 and E12 heads?

The following M10 cylinder heads appear to still be available through BMW. The list price on all is $1107.17 and the best price I found (same for each type) is $830.38 at Husker BMW. If I got any of the part numbers or info below wrong please correct me. I did not come across a part number for the 121TI head.

121 TI was a designation that was used on the early cars. It seems consistent that it was a combustion chamber shape vs. a model or specific year. We have a 1983 casting showing a simple "121" above the year. We used to see 83/84 castings on factory rebuild engines. The new E12s heads that we have are cast '87.

2002 121 Cylinder head

11120721008 (01/1968 - 08/1973)

Looks like a good # inventory would have to be checked See note above

2002 E12 Cylinder head

11129061432 (04/1971 - 12/1975)

Number looks good inventory should be checked

E21 320i M10 Cylinder heads

11121262178 (to 07/1979)......(2.0L)

11121268720 (from 07/1979)....(1.8L)

Part # 11-12-1-262-178 E21 Head (9/75 to 7/76 2.0l 2002)

Other #'s are good - check inventory

E30 318i M10 Cylinder head

11121273918 (07/1984 - 04/1991)....(1.8L)

Good # - same as above

Is it correct that the E21 320i heads have injector holes that need to be plugged and the E30 318i heads do not have these holes?

It has been quite a while since I have seen any of those cars so cannot confirm w/certainty as to which ones have the holes in the head, etc.

Fred '74tii & '69GT3

Although a dealer website may show inventory of any part, it is usually best to check the actual inventory in the US or Germany.

Share this post


Link to post
Share on other sites
Guest Anonymous

Are you changing the combustion chamber configuration (as in changing to a full hemispherical domed pistion)? If so easily done with a 121 and probably more easily done with an E21 2.0, not as easy with an E12 (my understanding is that an E12 needs to be welded in certain places then the material removed (not exactly sure on that one......). Many (many) years ago I had AlpinA make me up an new head for my engine, the head they selected was an E21 2.0, new casting easy to get from stock and easy to convert to full hemispherical chambers.

http://www.alpinabmw2002.com/2010/07/alpina-a3-cylinder-head-nos-great-story.html

Share this post


Link to post
Share on other sites

No, not on this car (the '69). On the big engine ('74 slide throttle project) we did a full hemi dome and it did not require any welding. Compression ended up around 13.8:1. Thanks to Alan and Rob for the additional input. Good to know what to look for in terms of late casting heads and also squish considerations. Great story on the Alpina head Mark!

--Fred

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.