Boring Out Throttle Body and Heads

[WickedBimmer]

I recently remembered that one of my friends owns a machine shop, n he told me he can bore out all of my parts for free etc...


so my question is... i heard the Dinan Throttle body for my 94 318is (4 cyc) car is basically just a bored out version of the stock throttle body..

does any one know the exact specs of the Dinan or any other performance company, in which i could tell my friend and have him bore out my intake throttle body...


or any specs for any parts that could be bored out for that matter...

heads, intake throttle body... (not sure what else can be bored for performance...???) ghead


also any suggestions or comments welcome...

Thanks in Advance, Wicked Bimmer!

[WickedBimmer]

basically what i need is the Specs of the aftermarket parts.. so i can have my stock parts bored out to the same specs...

Thanks again guys!

WBimmer

[Scarface]

I am interested in this as well, I am about to start saving some cash to go all out n/a on my 325i....gotta pay a few bills first!

[buuhh99]

be careful and make sure your friend knows what he is doin if you have him bore out your pistons or somethin like that and it is not exactly the right size of the piston i reall mean exactlly your engine will be so screwed up it isn't even funny. I have had some expirences with boring out snowmobiles and 4 wheelers and when someone messes up it isn't fun. the throttle body isn't so much to worry about but i would just make sure your friend knows what he is doin other than that go for it it would be sweet if it worked. take some pics while u do it so i can see

[Autotechnica]

You have an M42 correct?

My throttle body is bored to Dinan's exact specifications. ONLY the larger plate is bored 2mm larger, from 54mm to 56mm I believe. The smaller plate is left untouched. Dinan pretty much just bores out a stock throttle body, there's no trick to it. You just pay a hell of a lot more for god knows what. However, hopefully your friend does good work and makes a proper butterfly plate. If not, you'll have a very unstable rough idle.

Performance 318 exhaust pipes are usually anywhere from 2.25"-2.75". I'm using ANSA and I believe it's 2.75" all the way through.

Reguarding the heads. I think you'll be able to bore a maximum of 1.9-2.0L without going with a stroker kit. 1.9L is probably the safest as the heads on the M42 are quite thin, there's not an awful lot to take off. I don't know the exact bore specs, sorry.

Bry

[WickedBimmer]

Thank you very much Auto Technica!

yea, my friend owns a race shop, n i forgot that they had added a Machine shop n all of that this year... so he told me he can do of this work for free, so i figured why not... if anything id just pay one of his emplyoess a couple bucks to do it after work or sumthin

Thanks again!

if any one else has some exact specs, id appreciate it!

Thanks, JR

[EXtech]

To properly and effectively bore out a throttlebody it must be done all the way through. This means you also have to find a larger throttle plate. Secondly, I don't know what sort of racing and machine work your friend does but you must realize that porting a small block chevrolet head is nothing similar to porting a 4banger bmw head. It's not simply a matter of just hogging out metal. It's knowing exactly where, at what angle, what depth and how much to do so. Also, you will need other parts and upgrades with what you are wanting to do. Porting and polishing your cylinder head and opening it up for more flow will do you little to no good if you do not upgrade your camshaft. Often times changing the camshaft and porting the cylinder head will alter your engine's HP and TQ curves which therefore means you may need to change the gear ratio in your rear differential in order to realize the power. You will also need to consider your dme programming as well as fuel delivery. Then of course you need to consider your exhaust. A well and properly built engine is an orchestrated balance of engineered parts designed to work together to maximize horsepower and torque. I sincerely advise a carefully researched and organized approach to what you are wanting to do rather than yank a cylinder head and just start cutting metal or else you will end up with an expensive cylinder head for a paperweight and a 318 for yard art.

Just my two cents and expertise

[dutchbmw]

I can give you some measurements for the piston:
Standard: 83,93 mm (all for M42)
Max.: 84,48 mm

Boring (cilinder):
Standard: 84,00 mm +0,014 mm
Max. 84,500 mm +0,014 mm

This are the original BMW maximum overhaul diameters.
Hope you can count in millimeters, otherwise this is the convertation to inches:
25.4 mm = 1 inch or 1 mm = 5/127 inch

[Autotechnica]

Originally posted by dutchbmw@Mar 26 2004, 03:52 PM
I can give you some measurements for the piston:
Standard: 83,93 mm (all for M42)
Max.: 84,48 mm

Boring (cilinder):
Standard: 84,00 mm +0,014 mm
Max. 84,500 mm +0,014 mm

This are the original BMW maximum overhaul diameters.
Hope you can count in millimeters, otherwise this is the convertation to inches:
25.4 mm = 1 inch or 1 mm = 5/127 inch

great info, where did you find this?

[dutchbmw]

Originally posted by Autotechnica+Mar 26 2004, 10:00 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Autotechnica @ Mar 26 2004, 10:00 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-dutchbmw@Mar 26 2004, 03:52 PM
I can give you some measurements for the piston:
Standard: 83,93 mm (all for M42)
Max.: 84,48 mm

Boring (cilinder):
Standard: 84,00 mm +0,014 mm
Max. 84,500 mm +0,014 mm

This are the original BMW maximum overhaul diameters.
Hope you can count in millimeters, otherwise this is the convertation to inches:
25.4 mm = 1 inch or 1 mm = 5/127 inch

great info, where did you find this? [/b][/quote]
Found this in the 'Vraagbaak BMW 3-serie, met alle afstelgegevens' Translation: 'Questionguide BMW 3 series, with all adjust information'..... So when you need some tighten forces, ask me!!