Modified throttle bodies survey/thoughts

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Modified throttle bodies survey/thoughts

Post by bpoliakoff »

I am thinking of offering a service to enlarge throttle bodies by 2mm including new flappers which would allow for more aire flow. cost should be in the $125-$140 range plus return shipping. Thoughts?? Brucey please chime in.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: Modified throttle bodies survey/thoughts

Post by Brucey »

I would be interested in knowing if this either makes for a meaningful increase in power by itself, or is more of an 'enabler' so that you get more value out of other tuning changes. Everything makes a difference of course (all the flow resistances adds up) but the single biggest restriction is the valve time/lift of the standard camshafts. With a revised camshaft very healthy gains in power are possible, even without other changes, albeit that they come with less low rpm torque too.

I suspect that the TB being the size it is was originally because without at least a slight choke to the flow, there wouldn't be a good vacuum signal (esp near WOT) to control the ignition timing when using a distributor with vacuum advance.

IIRC the casting is pretty thin walled; I'm not sure if there is a real danger of breaking through or not. But overall it is one of those things that could do some good and (with the possible exception of breaking through the casting) oughtn't do any harm.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ron
Platinum Member
Platinum Member
Posts: 4569
Joined: Sat Jul 10, 2004 11:35 am
Location: South Wales U.K.

Re: Modified throttle bodies survey/thoughts

Post by ron »

"Jordanmilos" used to modify TBs. Lots of info. if you do a search.

I think he bored it out by around 4mm. I had one on MILI before I sold it. Can't find the pic now.
They are ALWAYS rustier than you thought!!!!!!
'85 M #228
'87 M #367
'88 High line.
'10 X5
‘84 Alfasud 1.5 ti
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

I have one of Jordan Milos' TB's on my car now, which hasn't been fired yet. I believe he was only taking them out 2MM but when I get over to where the car is I can throw a caliper on it and compare it to a stock unit. Jordan was also charging $250 per.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

This comment from the E9 forum..."Had a modified one on a Porsche, also on the 3.5 that was originally in my e9. Both improved responsiveness."
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
User avatar
Klaus
Posts: 221
Joined: Mon Dec 18, 2006 4:03 am
Location: Las Vegas, NV

Re: Modified throttle bodies survey/thoughts

Post by Klaus »

Bert, I might be interested in that, also have a few extra, early throttle bodies if you need some to play around with!

Klaus
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

Hi Klaus,Been a while. When I go to my machinist in a week or so to pick up my spin on oil filter adapters, I will bring him an extra Motronic body I have and we can measure it up and figure out what we can take out of it. He has been doing this to corvette TB's so knows what he is doing. Anyway, once we figure it out I will post up some more info. I bought mine years ago from another fellow that was doing them, but he was charging $250 for the same thing.Go figure!! Anyway, I will keep everyone in the loop
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
User avatar
clipper47
Posts: 596
Joined: Mon Oct 10, 2011 12:22 am
Location: Ontario, Canada

Re: Modified throttle bodies survey/thoughts

Post by clipper47 »

I would have thought that the highest airflow restriction would be at the Air Flow Meter not at the Throttle Body.
Dave
_____________
1985 635CSi US
Cosmos Blue/Pearl Beige
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

Read the comment from an E9 member 3 posts up
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
Kurtamine_
Posts: 66
Joined: Sun Nov 18, 2018 8:55 pm
Location: FL

Re: Modified throttle bodies survey/thoughts

Post by Kurtamine_ »

Would taking off that extra 2/4mm apply to only late model TB or would this also apply to early models too?

Anyone have pictures of this? or a link?
'81 E24
'99 miata
'84 E30
'99 eclipse
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

It will only be 2mm. First one is at the machinist being done at his liesure. We decided going any bigger is pushing it.that is on a Motronic TB
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
User avatar
Jordanmilos
Posts: 221
Joined: Mon Oct 23, 2006 9:33 pm
Location: Dulles, VA

Re: Modified throttle bodies survey/thoughts

Post by Jordanmilos »

I don't recall ever charging $250 for a throttle body. Even the ones that I powder coated and upgraded the linkage on, I think the most I ever got for one was $200. Stock throttles were in the $165 range with shipping included and no core. There is a good amount of work to get a throttle to seal properly, which includes machining the throttle body while following the original bore as it was machined from the DVG factory.

2mm is not anywhere near the limit of the throttle body if you set up the axial runout properly.
Big Bore Throttle Bodies, Gauge Kits, and more.... No more actually.
bpoliakoff
Platinum Member
Platinum Member
Posts: 3312
Joined: Thu Sep 28, 2006 9:28 pm
Location: scottsdale, arizona
Contact:

Re: Modified throttle bodies survey/thoughts

Post by bpoliakoff »

Jordan This seems to be turning into a pissing contest of some sort. i got my throttle body from you somewhere around 8 years ago . We exchanged parts for them and the value on the parts I traded to you, if I was to sell them, they were parts I was producing them at the time, was $250 as that is what I would have sold them for. Now maybe you figured them at a lesser value as the price you put on your throttle bodies was a lesser value so each one of us had a different idea of value at that point. Surely not something to debate when you take that into consideration. Usually in any kind of a trade each person has a different idea of value on their side. Same as in a car deal!
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
User avatar
Jordanmilos
Posts: 221
Joined: Mon Oct 23, 2006 9:33 pm
Location: Dulles, VA

Re: Modified throttle bodies survey/thoughts

Post by Jordanmilos »

It seems that every time you chine in on something having to do with my transactions, your facts are skewed to make yourself look like whatever it is you feel you need to look like.


Post by bpoliakoff » Wed Jul 16, 2014 4:50 pm

Rubber not available separately. Years ago, I was having identical,die extruded rubber to match the originals. I ran out of them and never had more made. I was the only source doing this world wide.

I have to order them in quantities of 10 sets. So if 10 guys step up, I will do them for $150 a pair providing the fellow who made the dies for me still has the dies and and extrusion machinery and is still "kicking"


I gave factual info on the bore size and expalined to anyone who was willing to read and get that information, that the inflated value of what you claimed I charged was simply false.
Last edited by Jordanmilos on Mon Jan 21, 2019 1:24 pm, edited 1 time in total.
Big Bore Throttle Bodies, Gauge Kits, and more.... No more actually.
User avatar
TBM
Posts: 342
Joined: Tue Apr 15, 2014 4:05 pm
Location: California
Contact:

Re: Modified throttle bodies survey/thoughts

Post by TBM »

I would like to chime in regarding the increase in bore. Since I am on a path of increasing flow to the head I have done some research regarding boring. I would first concentrate on Throttle body Bore size as a velocity is vital in atomization. There is research and Real world results that show that converting a throttle body to a shafless unit will increase flow by up to 12 percent when you get rid of the "hump" in the butterfly. It's more complex to convert BUT as I am working on this now I may be able to help later with input.
AT-Power .jpg
AT-Power .jpg (60.44 KiB) Viewed 11051 times
'84 M635csi
'86 Lotus esprit Turbo (sold)
Kurtamine_
Posts: 66
Joined: Sun Nov 18, 2018 8:55 pm
Location: FL

Re: Modified throttle bodies survey/thoughts

Post by Kurtamine_ »

Jordanmilos wrote: Sun Jan 20, 2019 2:20 am It seems that every time you chine in on something having to do with my transactions, your facts are skewed to make yourself look like whatever it is you feel you need to look like.


Post by bpoliakoff » Wed Jul 16, 2014 4:50 pm

Rubber not available separately. Years ago, I was having identical,die extruded rubber to match the originals. I ran out of them and never had more made. I was the only source doing this world wide.

I have to order them in quantities of 10 sets. So if 10 guys step up, I will do them for $150 a pair providing the fellow who made the dies for me still has the dies and and extrusion machinery and is still "kicking"


I gave factual info on the bore size and expalined to anyone who was willing to read and get that information, that the inflated value of what you claimed I charged was simply false.
With this being said I would be interested in being apart of the group of 10.
'81 E24
'99 miata
'84 E30
'99 eclipse
Kurtamine_
Posts: 66
Joined: Sun Nov 18, 2018 8:55 pm
Location: FL

Re: Modified throttle bodies survey/thoughts

Post by Kurtamine_ »

TBM wrote: Sun Jan 20, 2019 2:59 am I would like to chime in regarding the increase in bore. Since I am on a path of increasing flow to the head I have done some research regarding boring. I would first concentrate on Throttle body Bore size as a velocity is vital in atomization. There is research and Real world results that show that converting a throttle body to a shafless unit will increase flow by up to 12 percent when you get rid of the "hump" in the butterfly. It's more complex to convert BUT as I am working on this now I may be able to help later with input.

AT-Power .jpg
TBM, I not only agree but I also value your input on the subject of removing the shaft hump from the scenario of obstructing volumetric flow. Have you tried this setup on your car yet? Anything noticeable?
'81 E24
'99 miata
'84 E30
'99 eclipse
User avatar
TBM
Posts: 342
Joined: Tue Apr 15, 2014 4:05 pm
Location: California
Contact:

Re: Modified throttle bodies survey/thoughts

Post by TBM »

Kurtamine_ wrote: Fri Jan 25, 2019 12:23 am
TBM wrote: Sun Jan 20, 2019 2:59 am I would like to chime in regarding the increase in bore. Since I am on a path of increasing flow to the head I have done some research regarding boring. I would first concentrate on Throttle body Bore size as a velocity is vital in atomization. There is research and Real world results that show that converting a throttle body to a shafless unit will increase flow by up to 12 percent when you get rid of the "hump" in the butterfly. It's more complex to convert BUT as I am working on this now I may be able to help later with input.

AT-Power .jpg
TBM, I not only agree but I also value your input on the subject of removing the shaft hump from the scenario of obstructing volumetric flow. Have you tried this setup on your car yet? Anything noticeable?
I'm in the process of setting it up. My results will be hard to quantify unless I run back to back with Original ITB's when we flow the head.. I will try but not sure if I will have the chance.
'84 M635csi
'86 Lotus esprit Turbo (sold)
VintageRacer
Posts: 87
Joined: Sat Jun 24, 2017 2:49 pm
Location: Waco, TX

Re: Modified throttle bodies survey/thoughts

Post by VintageRacer »

Just curious why everyone wants to stick with the OEM TB?? There are plenty of generic, Honda and mustang throttle bodies out there for 50-150$ all day long new and used. These range from 65-105mm depending on the application. All you need is a simple four bolt adapter made from 1” aluminum plate. Pretty easy to make even on a manual machine. The mustang 5.0L BBK 70mm unit I got for 75 on eBay even has the idle air control and TPS.

A little research and the plug on the mustang IAC is the same as the motoronic one. The tps would require some fab to use the stock one but I’m going to be running Megasquirt.

I suspect that anyone needing a larger TB to this magnitude won’t have issues with these minor fabrication tasks.
User avatar
Jordanmilos
Posts: 221
Joined: Mon Oct 23, 2006 9:33 pm
Location: Dulles, VA

Re: Modified throttle bodies survey/thoughts

Post by Jordanmilos »

It comes down to a matter of cost. You’ll be likely to spend twice as much getting a different throttle body on the car, and then you have to open the manifold to match any higher bores.
Big Bore Throttle Bodies, Gauge Kits, and more.... No more actually.
Pod
Platinum Member
Platinum Member
Posts: 4492
Joined: Tue Mar 16, 2010 8:32 pm
Location: usually in the barn, Kent, England.

Re: Modified throttle bodies survey/thoughts

Post by Pod »

TBM wrote: Sun Jan 20, 2019 2:59 am I would like to chime in regarding the increase in bore. Since I am on a path of increasing flow to the head I have done some research regarding boring. I would first concentrate on Throttle body Bore size as a velocity is vital in atomization. There is research and Real world results that show that converting a throttle body to a shafless unit will increase flow by up to 12 percent when you get rid of the "hump" in the butterfly. It's more complex to convert BUT as I am working on this now I may be able to help later with input.
I'd be very interested to hear how your installation works out!
Post Reply