I have the b34 with 8.0 cr....
Has anyone messed with using epoxy to raise cr?
I know i can measure the outcome with oil/fluid.
What would be the results if attempted?
Robert
04' 325Ci (Daily Driver)
03' X5 (Wifes)
I can't imagine the outcome would be worth the trouble, why would epoxy in the cylinders be a good idea? You can easily find forged pistons for just about any engine, or you can look for a set of B35 pistons if you want to raise the CR...
Or do a B35 swap like I'm currently undergoing. There's lots of good documentation on mye28.com, engine mounts are available, and you go from 8:1 to 9:1, 182hp/210ft/lb to 208hp/225ft/lb. Slightly better fuel economy, and 264 degree cam over the B34 260 degree.
Plus B35 came in a lot of high-production cars, like E34 535i and E32 735i, so finding a good one shouldn't be a big deal. Or get one out of a 1988-1989 635CSi.
EDIT: Just noticed you've got a 633, so you'd notice an even bigger difference over a 635CSi.
Last edited by volac; 06-17-2012 at 04:45 PM.
85 635csi Resto-mod: Holset,Megasquirt,Billies,H&R's all the goodies.
Pure and simple, that is rediculous. You will crap up your whole engine. Just get your head milled, use an adjustable cam gear to compensate for the milling and be done with it, or step up, spend the money and do a B35 engine or a proper rebuild on your engine. HP costs money and no easy way out.
81 Euro undergoing total nut and bolt restoration
pictures at: flickr.com/photos/bertsphotos
Ok, i think i have the general thought on this.
What would be the advantage(s) in milling the head to get say a 9.4 cr; on a stock/semi stock 3.4?
Robert
04' 325Ci (Daily Driver)
03' X5 (Wifes)
With no offense meant to the OP, I'm afraid this may be a case where a little knowledge is dangerous.
Although you don't specify where you are going to add "epoxy" to reduce the cylinder volume (either on top of the pistons or in the head combustion chamber) to achieve the higher compression ratio you desire I cannot see where you could do this effectively for any long term purpose. I realize that there are some magic expoxies out there but I haven't heard of any that will withstand the dynamics that are involved inside the 4 cycle/4 stroke engine. I'd like to know if you have found one and how you intend to accomplish this endeavor.
Quite simply I believe that your best option is to do what the other posters have suggested rather than experiment with something that may entail a lot more R&D as well as expense than taking the "standard" way out. However if you have some info regarding the use of epoxy in regards to reliably raising compression ratios I would like to know as if something new is available to do so I'd like to learn about it.
As I said, I mean no offense, I'm just interested if you've come across something new. Although I'm retired now, I've built high performance and race engines for over 35 years and ran a race engine machine shop and haven't heard of this before.
Thanks,
Tom
Tom
Current Rides:
1995 318i-Da Kid's Car Now!, Great Little Car "Pearl"
1987 Porsche 944 "Liebchen"
2002 Porsche Boxster "Sunbeam"
2004 X3 "Xander"
Past Rides:
Over 50 Years Worth..Way Too Many To List, But There Were Some Really Fun Ones!!!
www.ttrs1.com
Reminds me, in all due respect to OP, of the story on the Audi board of the guy who put sand in the motor to sandblast clean the cylinder wall and combustion chamber.
Reminds me, in all due respect to OP, of the story on the Audi board of the guy who put sand in the motor to sandblast clean the cylinder wall and combustion chamber.
Reminds me, in all due respect to OP, of the story on the Audi board of the guy who put sand in the motor to sandblast clean the cylinder wall and combustion chamber.
Reminds me, in all due respect to OP, of the story on the Audi board of the guy who put sand in the motor to sandblast clean the cylinder wall and combustion chamber.
really.....
Epoxy is used in manifolds all the time to contour radius'.
A bit much to compare the thought to filling sand into a cylinder.
And yeah... i do take it personal. why else would you have posted the comment?
Nice multi posting by the way.
Head porting. http://www.allpar.com/fix/holler/head-porting.html
TJC1 - the idea was to just apply it to the sides, in between the valves. Just to gain a little more cr. I haven't seen much of anything on using it inside the cylinder head(cylinder), but as the hyperlink shows it is used inside the runner.
Last edited by rvaughnp; 06-17-2012 at 09:53 PM. Reason: Automerged Doublepost
Robert
04' 325Ci (Daily Driver)
03' X5 (Wifes)
Using an epoxy product in an intake runner is not that uncommon, but understand the intake has a cool/cold air and sometimes fuel charge coming through it. Also the intake valve is mostly closed (allowing for overlap) during the igniton, power and exhaust phases of the four stroke cycle which account for the greatest heat in the combustion chamber.
The thermal dynamics inside a combustion chamber is a much different circumstance.
EDIT:
Also, if you attempt to "fill" the combustion chamber of the head as you suggest you will effectively change the internal design in such a fashion that you will "shroud" the valves which will lead to extremely inefficient combustion and a loss of power. One of the key goals in head and combustion chamber porting is to create an atmosphere that promotes as complete combustion as possible and one way to achieve this is by "unshrouding" the valves. Keep in mind that any combustion chamber design whether it be pent, hemisperical, or whatever is designed in conjunction with the piston head design to provide an area for the air/fuel mixture to be as atomized as possible so when it is compressed and ignited maximum energy without waste may be achieved to give the most power and efficiency for the particular intent of that engine or car it is being used in at the time. I could go on and on, but this isn't really the place for a full dissertation! Now granted today's engines and designs along with engine management systems are far more advanced than what these old Sixers were so it would be unfair to do a comparison so if you are to work within the parameters of what you have I still suggest that you consider some of the suggestions given by the previous posters as your best alternative to getting the power that you desire.
Last edited by TJC1; 06-17-2012 at 10:42 PM.
Tom
Current Rides:
1995 318i-Da Kid's Car Now!, Great Little Car "Pearl"
1987 Porsche 944 "Liebchen"
2002 Porsche Boxster "Sunbeam"
2004 X3 "Xander"
Past Rides:
Over 50 Years Worth..Way Too Many To List, But There Were Some Really Fun Ones!!!
www.ttrs1.com
As evidenced from the other replies, your vague description in your original post led us to believe you were going to slap some expoxy in the combustion chamber, and as such, IMHO, nothing wrong with a little humor. You should get in touch with Paul Burke who's a frequenter on Mye28 for a most qualified opinion. I'm not one to cause strife on the boards, so I'm sorry that I insulted you.
Wish I could find the link, it's a fun read.
I could only imagine the responses if the question was posted on mye28...
Last edited by ShapeShifter; 06-18-2012 at 09:22 AM.
Car 1: '86 BMW 635CSi - Delphin Grey Metallic, K&N Cold Air Intake, Miller Performance MAF Conversion, Chipped, 17" Wheels, Bavauto Short Shift, Bilstien Heavy Duty Shocks, Ireland Engineering full exhaust 246,000 miles
Car 2: '99 Cobra - Black on Black, UPR Underdrives, JLT Ram Air Intake, Short Shift, Bassani O/R X-Pipe, MAC 2.5" Catback, 3.73s 205,000 miles
1996 Saab 900 Turbo - Sold
1995 VW Jetta - Sold
2007 Buell XB12R - Sold
1981 Honda CB750C - Sold
1986 BMW 535i - RIP
IMO if you're swapping engines don't even go for an M30. Go for an M52, S50, S52, or M54. All of them should be able to swap into the E24 without much hassle.
http://www.b15sentra.net/forums/showthread.php?t=168736
I laughed when I saw the bricks
Mine: 1988 635CSi Euro in Diamantschwarz Metallic, 1989 ALPINA B10 3.5 in Alpineweiss II, 1981 528i in Kastanienrot-Metallic, 1958 Isetta 300 currently in rust repair
In the family: 1958 Isetta 300 in Federweiss/Pastellblau, 1987 635CSi, 2000 M5
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You can change your compression ratio by;
1. Milling down the head.
2. doming your pistons.
I've never seen anyone fill in the valve area. When you stated "has anyone messed around with epoxy to change their CR", we all assumed you were going to dome a piston with epoxy. You cannot mill a head down with epoxy. Then you state that you "know I can measure it with oil/fluid". This means measuring the volumes of the head and the bore and comparing the ratio between the two. So you inferred that you were going to reduce the head volume at TDC by doming the piston.
To answer your question "what would be the result?" You would destroy your engine.
Mixing dissimilar materials is never a good thing. Epoxy at high temperatures bonded to steel is never going to be durable. If you have an engine with a CR of 8.0, Turbo it!!! That's the perfect CR for a turbo conversion and you can really up the boost.
To be fair to the original poster I jsut looked at both links, the epoxy porting link (not for CR) and the "watch me tape a steel plate to my piston" link.
Firstly - Taping a steel plate to the top of the piston is so shonky (think your plumber giving you brain surgery), so hack that it is not funny. Why not just strap a boot to the top of the piston? I’m sure that will soak up some volume. This must be the worst back yard engine mod I’ve heard of in a long time. Seriously, high compression pistons can be got from $600 new for 6. Second hand you may only need to spend a few hundred.
Epoxy'ing a cylinder head to improve flow/swirl may work, for poor flowing heads but will in no way affect CR. Swirl is used to mix the fuel and air. Most heads, despite injectors spraying the fuel into the head, end up with fuel dripping in, in drops. This is why porters say that you need as rough a surface as possible when you port. The rough surface does not improve airflow (and we all think we want more air in so smooth surfaces. Guys more air in does not mean more combustion or hp, sometimes more air means less combustion) but does cause eddies in the airflow. Little tornedos or whirlpools you could say. This mixes the fuel and better giving improved combustion and hp. Mixing the air and fuel in a solid steel head without a mixer is the trick. There’s where you maximise your hp.
The B34 head is a good head. Porting helps to open up areas but it is an advanced head. The B35 head is the next step up. I've talked to M30B35 racing engine builders who all say that "there is little this head needs". The B34 head can never be ported up to a B35 head. If you port a B35 head your main aim is to better mix air and fuel. BMW got the best out of their heads that they could. American muscle car heads were low tech and could really benefit from porting. B35 BMW heads are much closer to a performance option.
Last edited by Shipper; 06-18-2012 at 08:08 PM.
1977 633 CSi RHD Euro. S38B38 3.9L M5 Transplant. 5 Speed Getrag Dogleg. 3.73 LSD. 417hp, 369lb/ft
1971 3.0CS E3 2dr Alpina Special Coupe Racer, 347hp, 295lb/ft
To all those who took this question with some relevant thought... thanks.
To all the other immature children who didn't......
Shapeshifter and Adambath... that was actually cute. I like humor.
Done.
Robert
04' 325Ci (Daily Driver)
03' X5 (Wifes)
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