Author Topic: dual trottle bodies (Read 4718 times)

4banger · « **on:** February 20, 2010, 07:23:37 AM »

anyone ever toyed with the idea of dual tb's? wonder if something like this could be adapted to our m42's. http://www.extrudabody.biz/servlet/the-90/2-dsh-ITB-dsh-KIT-dsh-40mm-fdsh-45mm-fdsh-48mm-or-Single-DCOE-fdsh-IDF-fdsh-IDA/Detail

4banger · « **Reply #1 on:** February 20, 2010, 08:14:21 AM »

after a little more searching on extrude a body's site they have the flanges too. to me this looks viable. http://extrudabody.com/Products/BasePlates.html

the tb's have injector ports machined in to them. you could run a dual stage injector setup. if you used a dual tb setup you would have a total of 6 injectors. if you ran a 4 itb setup you could have 8 injectors. kinda like the s42

Victorymike18 · « **Reply #2 on:** February 21, 2010, 06:20:16 PM »

I'm not sure I quite understand what you're getting at.

Are you talking about mounting these in pairs, to the head (so each throttle bore lines up with the intake port)? If-so, you are essentially thinking if individual throttle bodies (ITB'S) which is an often-discussed topic.

Or, are you thinking of using a single (pair of throttle bores) one of these, to replace the stock throttle body on the M42, while retaining the OEM intake manifold?

4banger · « **Reply #3 on:** February 21, 2010, 06:23:56 PM »

it would use a custom manifold where the runners would be paired up. 1 tb for 2 cylinders. 2 50mm tb's would be more than enough to feed 4cylinders. and the tb's have a standoff machined into the base. you could do a dual stage injector setup.

Victorymike18 · « **Reply #4 on:** February 21, 2010, 07:26:32 PM »

I see on their website that the bodies are available in 40mm or 45mm diameters. I haven't personally had the manifold off my M42, so I have no idea of the stock intake port bore size.

That being said, I'd suggest running four individual bores of a smaller diameter each, over two larger bores feeding a pair of cylinders. The reason I say this is because using four throttle bodies would naturally isolate the pulsations from each intake bore (especially beneficial when running large duration cams).

If you use only two bodies feeding two bores each, the pulsations will negatively interfere with each other on the intake stroke. There are ways to design around this, but it's much easier to simply run one throttle body per cylinder.

Another thing to consider: What engine management are you going to run these throttle bodies on? If you plan to run the stock fuel injection, then you might want to reconsider, as this will be a very high cost for little to no benefit. In-fact, you'd probably loose low-end torque, and gain little top-end.

Do you have any cylinder head modifications?

Now, I believe there's a good thread on here regarding ITB's on the M42. If I recall correctly, it's been shown that expensive intake modifications are of little gain unless the head is worked accordingly. I'll see if I can find the thread to reference it.

All that being said, I'm new to these motors, so take my comments with a grain of salt.

Quote from: 4banger;88060

it would use a custom manifold where the runners would be paired up. 1 tb for 2 cylinders. 2 50mm tb's would be more than enough to feed 4cylinders. and the tb's have a standoff machined into the base. you could do a dual stage injector setup.

4banger · « **Reply #5 on:** February 21, 2010, 07:39:54 PM »

not if you pair up the runners with the pulsations. same goes with a header. im well aware about the ITB setup. ive read the thread and i do have a shit load of headwork and hot cams waiting for my solid lifters to come in. . this is just a idea but to me duals seem viable. it will be running megasquirt. ive thought all of this out. guys are running 35-40mm bike tb's i dont see how 2 50mm's could do worse plus you have the option of potentialy having 8 injectors like a s42. itb's may be easier but its also $1000 more on the tag.

Ryann · « **Reply #6 on:** February 21, 2010, 11:49:34 PM »

There used to be a legendary intake manifold called the Lynx for the 2002 that used one twin-butterfly DCOE sidedraft Weber, and it was split in half by firing order (1&4, 2&3) so that each throat/throttle of the carb was utilized by two bores, lacking the negative effect that Victorymike's talking about.
At the risk of sounding like a nay-sayer though, I think it's tough to out engineer BMW on a proper intake setup that'll deliver more power and retain drivability.
On the other hand, if it's all about throttle response it could be a worthwhile mod.

e30_03e · « **Reply #7 on:** February 22, 2010, 01:51:10 AM »

looks no one's heard of dbilias?

?
Otto from KOED was selling his but I'm sure they are out there....

4banger · « **Reply #8 on:** February 22, 2010, 04:38:16 AM »

yes we have all heard of dbilas. but look at the price too. 2002faq.com sells them in their store. $2800 and takes 2 months to get. http://www.bmw2002faq.com/component/page,shop.product_details/flypage,/product_id,111/category_id,18/option,com_virtuemart/Itemid,59/ for under a $1500 inluding megasquirt i could put this setup together and still have allmost a thousand left over for tuning costs. dyno time ect.

ryan using the firing order/pulses is how alot of headers are built. when i built mine i paired up cylinders 1&3 2&4.

Massimo · « **Reply #9 on:** February 24, 2010, 01:00:09 AM »

Has anyone ever tryed these

http://www.efihardware.com/products/716/race-series-4-cyl-economy-kit-DCOE

They are heaps cheaper and all you need to do is make an adaptor plate or buy one from these guys.

I just realised that probably not because they are Australian. Anyways they are alot cheaper. If i got itbs one day i might try these out.

deekay · « **Reply #10 on:** February 24, 2010, 01:16:31 AM »

Quote from: Ryann;88079

There used to be a legendary intake manifold called the Lynx for the 2002 that used one twin-butterfly DCOE sidedraft Weber, and it was split in half by firing order (1&4, 2&3) so that each throat/throttle of the carb was utilized by two bores, lacking the negative effect that Victorymike's talking about.
At the risk of sounding like a nay-sayer though, I think it's tough to out engineer BMW on a proper intake setup that'll deliver more power and retain drivability.
On the other hand, if it's all about throttle response it could be a worthwhile mod.

the lynx is actually still available.

http://www.racetep.com/weber/0245single.html

the idea of getting one of these manifolds and megasquirting an m10 with a dual-TB unit from TWM has crossed my mind. would be quite a good street setup, i think.

and not to be argumentative, but BMW kinda did cut corners on the e30 version of the m42 in a few places... i am very happy with the changes made by the dbilas setup myself, but then i didn't pay $2800 for it, or even half that... at that price i'd be looking for a different solution also.

anyway OP i support your efforts, and think the suggestion of using something designed like the lynx manifold is a great idea.

4banger · « **Reply #11 on:** February 24, 2010, 01:41:14 AM »

im going forward with it. i got a lower intake cut up and milled the runners down. waiting for runner tubing and the TB flange from the guys i linked. 2 45 or 50mm tb's with a secondary injector setup. after i get everything fabbed up then ill move on to the engine managment bit.

deekay · « **Reply #12 on:** February 24, 2010, 02:29:25 AM »

this brings up interesting questions. stuff i never got far enough to think about when i was considering an m10 car.

i wonder how you're going to want to size them, first off. is the fact that you're drawing two intake strokes through each TB going to warrant going bigger than you would on a 4-TB setup? or since the intake strokes through each TB are going to be 360deg opposed (right?) are they effectively going to not interfere with each other and you can run about the same size? i'd investigate how the 2002 guys change the carb setups on single- vs dual-sidedraft setups.

are you going to be able to set up megasquirt (or whatever) to use two injectors and fire twice as often?

i love seeing people blaze trails. good luck.

4banger · « **Reply #13 on:** February 24, 2010, 02:50:23 AM »

i havnt got the intake totaly worked out yet but i was leaning towards having the TB's as a true side draft. but then my runners wouldnt be equal length. ive got a few lower intakes i can hack up and use. i supose it will be trial and error but isant that how R&D work goes?

planning on mega squirt. it will use the 4 injectors mounted in the bosses on the intake and 2 secondaries mounted on the tb's. s42 used 8 injectors why cant i use 6? the biggest cost is gonna be the tb's and the engine managment. ill be doing all the fab work my self and by chance my dad is a machineist by trade so i have access to a well stocked shop.

edit* after looking at the lynx m10 manni again after my bends on the runners and bending for space at the flanges my runners may come out to be damn near equal length. i still think its viable for under the $3000 dbilas set up.

deekay · « **Reply #14 on:** February 24, 2010, 12:50:45 PM »

i don't know if you're going to need that much fueling, honestly. 24lb'ers had my car cooking when i was using the alpha-N; after going back to the AFM i found it worked the best with 21lb/hr and a little extra rail pressure. still need to get my wideband in so right now it's just tuned by ear, but yeah... if you're going to retain the mounting bosses in the part of the original lower manifold that you use, i really think you'll be good with one of those two choices and the FPR you're working on.