Question for Winfred about his +5mm Throttle body

[DanDombrowski]

I was wondering how you enlarged your throttle body if you happen to have machined it yourself. I was thinking of doing it to mine, but I keep running into snags. First, I can't put the thing in the lathe because of the weight imbalance. I might be able to put it in a BIG lathe, but if I tried that on our smaller ones at the schools machine shop the guys running it would **** a brick. Anyway, I was then thinking I could mill it, but I don't know how to make a circular cut with a standard mill, only on our CNC. Just wondering how you did it before I reinstall the CAD program to cut on the CNC. Thanks.

[ryan roopnarine]

but if your serious about doing it, and can wait, i have a spare m50 throttle body in orlando that i could pick up during spring break, so you don't end up fuxoring your primary means of transport

[
QUOTE=DanDombrowski]I was wondering how you enlarged your throttle body if you happen to have machined it yourself. I was thinking of doing it to mine, but I keep running into snags. First, I can't put the thing in the lathe because of the weight imbalance. I might be able to put it in a BIG lathe, but if I tried that on our smaller ones at the schools machine shop the guys running it would **** a brick. Anyway, I was then thinking I could mill it, but I don't know how to make a circular cut with a standard mill, only on our CNC. Just wondering how you did it before I reinstall the CAD program to cut on the CNC. Thanks.[/QUOTE]

[DanDombrowski]

Actually, I was going to do it to the spare volvo TB for my volvo first, then if that worked out, to a spare BMW one. I know my skill with the machine tools, and I'm almost planning on screwing up the first one. Stuff on the lathe I'm decently good at, but I don't have much practice on the mill which is probably what I'm going to need to do. If it gives any kind of increase in torque I might even make a few to sell.

[Dave M]

Go Dan.

Keep us posted,

[632 Regal]

the higher the power band will be, kinda like over carbureting. It will likley kill more low end.

Just my 2¢

[winfred]

i have a buddy with a machine shop that figured out that a m50 butterfly will bolt to a m20 shaft, and is around 5mm larger then the m20, i miked the walls of the throttle body and they are down to 1-1.5 mm thick. the m50 and m30 have the same size butterfly for those wondering

[DanDombrowski]

so basically your M20 TB is the same size diameter as an M50 TB?

[winfred]

it is now

[winfred]

at the moment i almost have enough torque to smoke em without dumping the clutch in a straight line, it's fun on wet roads, no surface can handle more then 1/2 throttle in 1st, almost all surfaces can't handle 2nd above 3500 rpm and some times it will even break em loose in 3rd when it gets on the cam, 3.73 posi, i don't even wanna think about a 4.10, 1st is usually useless in a I with a 5 speed and a 4.10. the coolest experament i've done with the 325, was a close ratio 5 speed from a e36 318, sob would come off the line like a bat outta hell but i missed having a overdrive, i do too much interstate driving to deal with 4+ grand at 80


the higher the power band will be, kinda like over carbureting. It will likley kill more low end.

Just my 2¢

[DanDombrowski]

all this from a +5 mm increase in the TB? SIGN ME UP! Haha, well, if I plan to bore mine out, I'm going to have to machine my own throttle plate, but that shouldn't be a problem- just get the diameter of the new intake size and lathe down a piece of aluminum, drill two holes (mabye even put the holes in the right places?). Now this introduces the question....will I have a lip from the opening on the intake manifold and have to grind (plastic, I know) that out, or will it accept a bigger bore TB?

Thanks for the advice also, Regal. Since I have Vanos, don't you think that my motor would make better use of more airflow in the mid to upper range?

At the very least, even if I can't bore the thing, I plan on knifing the edge of the throttle plate and grinding down those small set screws that hold it in place and running it through the flowbench to see if it helpes.

Dan in Gainesville

[winfred]

dinan chip, bosal top sport catback, 19# mustang disc type injectors, 5mm ob tb, mildly ported intake, bas full length jethot coated (about the same heat as stock manifolds) headers, modded 535 afm (tb aint worth **** if the afm is the same size as the old tb) mounted to a modded stock airbox, that's about for the current mods, it's about the same accelleration as a stock e30 m3, i dragged the boss once when he was in his 88 m3 before all of the mods, and i can pull a stock 325i with the same gearing as me at about the same rate the m3 pulled me. but i have two more pistons so my power band is a little lower, id like to put a 4.10 in my 325 and drag another e30 m3 and see how it does with the same gearing as the m3.
future mods, 2.9 stroker with steel crank, lumpy cam, thinking about a 286 shreck, extrude honing through out the intake and head, hot wire/film ams conversion, i am thinking about 9.7:1 compression forged pistons, possible larger valves if the airflow needs of the motor demand it, otherwise stock valves to keep port speed up..... blah blah blah

[DanDombrowski]

Oh I was kidding, I knew it wasnt just from that, I saw the few mods you had from your sig. My volvo has a hot wire AFM, if I could find some info on calibration, I could easily modify it to the BMWs, as I've taken classes and labs on instruments and measurement (hated that class, hated it). Basically, I could modify the output voltage so its what the ECU should expect, but I would need to know a couple of "If I have this much air going through, this is my output voltage" data points for calibration. Holy ****....I'm learning in school! Time for more beer!