BDC

Hey guys. Nick Barnett (Kurgan) originally posted this in the 20B Forum underneath this forum here but I wanted to toss it out here and get some feedback from you guys. Per a simple idea I originally got from Shane Tofts that I expanded on and developed some, I've been doing some 2nd gen throttle body porting and polishing jobs. I've already done several and look forward to doing more. I originally tested this mod on my own throttle body to see what it would do. It includes the "standard" mod which removes the 4th and 5th (secondary) butterflies and rotating shaft/thermowax hardware as well as re-shaping of the insides to allow for a better airflow transitioning from the inlet to the outlet of the body itself. I've taken a gander at the FD Tbody and I don't believe it's worth pursuing. It can be knife-edged a bit and cleaned up in terms of polishing but I'm not convinced there'd be any benefit to it.

Here's a couple of links of two pictures:

20BREW Throttle Body Modified

13BT Throttle Body Modified

The things I've noticed from this modification are substantially better throttle response (even over the removal of the secondary set of plates), much better throttle on-off jerkiness, as well as drastically improved low-end power and turbocharger response. I have no dyno figures as of yet but hope to have some showing some before and after graphs in the next couple of weeks. My aim is to widen the torque curves on our cars and increase the efficiency of each (stock) component to make the vehicle run better in general. This is just one of many areas that needs improvement, in my opinion.

It takes me not quite all day long (standard work day) to perform one of these modifications as they're all done by hand. I'm currently offering this modification to anyone who'd like to give it a whirl. Since I'm having problems finding spare cores, downtime will be about 2 days per TBody I receive to do work on. I can be reached at bdc196@attbi.com. Toss me a line and let me know what you think as well as any questions you may have. Thanks.

B

RICE RACING

BDC, I taught shane that mod !

I have been doing them for the last three years, and have noticed all the benifits you mention. Devcon is needed on the most radical versions I make as there are a lot of "holes & gap" that open up after "hi flowing" the TB.

I believe it is worth up to 2 to 3% in engine power alone.

Nice work, good to see others doing it

BDC

Yep =) I originally got it from Shane one day but wound up evolving it over time into how it's turned out now. It's kinda one of those "why didn't I think of this!" ideas, ya know. =) Makes me look more closely at everything else in the engine bay (and specifically the entire intake tract) to see what else can be done.

Thanks a bunch. Glad you enjoyed it =)

B

duboisr

Garfinkle does 3rd gen TBs ,he uses counter sink screws to hold the plates in to improve flow . he plugs all extra holes and ports from the outside and blends the plugs on the inside so nothing can come lose and get sucked in .

Bitchn7

Heyt RICE, does this work with the S6 T-Body (or in my case a 20B t-body)?
Shane has just recently told me about this and has offered to do mine fo me and I have a spare to send him if its worth it on a 20B T-body

HWO

I'd say it works for any throttle body with multiply butterflies...................

months back Peter told me about this, i did it to my TB and had good results, I then told Brian about it who did it and had good results who then did it to a few other guys TB's

to use Peter's phrase "its worth its weight of alloy grindings in gold"

BDC

Yep. One of the two pictures I posted was from a 20B throttle body. It works well !

B

twister

Hi, here is a link to a throttle body injection system used on a Gen 1 racecar here in OZ, this one is producing (bp) approx 290 hp at the rear wheels.

Judge Ito spoke to Rohan recently in NY re this I believe.


http://www.gurumotorsports.com/engines/ambrose_efi.jpg

HWO

umm ....... whats that got to do with getting higher flow from the factory S4/5/6/7/20B Throttbel bodies? that set up is for a N/A motor not a force feed one.

Anthony Rodrigues

After removing the extra butterflies to encourage less interupted inlet flow, there is no out right power gains to be gained from s.4/5 or 6 throttle bodies without extensive inlet manifold modifications. The lower section of all of the above inlet systems are the weak link in the inlet. It does give better throttle response that is why we have been doing it in Aus for the past 5 or so more years, but that is about it.
Regards-Anthony

cach22

Anthony:

Yeah i agree, i was actually having a look in my jc cosmo plenum, and the ports look quite small, especially if you consider the circumference of the engine inlet port compared to the circumference of the port in the manifold, is this basically what you are saying is the restriction?

cheers

BDC

The point of the TBody mod is to reduce four flat spot areas. The idea is to retain intake charge velocity through the entire throttle body, increasing low and mid-range response and torque. Overall power increase probably is fractional.

B

Anthony Rodrigues

If you flow the top, bottom sections and the t/b seperately, you will find the least cfm flow in the bottom section. regardless of changes to t/b or upper section mods, you cannot improve on the total flow.
Regards-Anthony

BDC

That's correct, Anthony. Total flow throughout the throttle body is not being changed as evidenced by the fact that the throttle butterflies aren't being changed at all. There's no claim to increase in total flow, but I'll tell you right now that total flow isn't the only thing that equals more power. If I can widen your torque curve and make it "become alive" 500rpm or even 300rpm earlier than it would have by retaining intake charge velocity, your car will accelerate to an even speed more quickly than it would have, which means it's faster. The purpose of this modification is to essentially remove a bottleneck; not make the bottle any bigger.

B

Kurgan

My 20B TB that BDC did looks awesome. I also have a port matched upper and lower intake, and the lower intake is port matched to the engine ports. I have a stock TB as well, unmodified for the 20B. I plan on gettin the car up to par with Bryans TB, then getting a Dyno reading... then swapping the stock TB in and seeing what the difference is on the dyno...

My car SHOULD be running next weekend... I just keep running into problem after problem. The bumper I ordered was warped, my headlights are still in Japan... when stuff like this happens, I just don't have motivation to go and do anything to her... After mounting the Fluidyne and black magic fan this week, its fairly obvious that with the angle I had to use to get the 19" tall radiator in the engine bay, that radiator is just too damn tall... so now I'm selling the radiator and getting a custom one... much wider and a bit shorter. After that, and IC pipes and a downpipe, it'll be ready to run on the back roads... since she has no headlights or front bumper, I gotta watch it I just want to drive it so bad.. blah.

Anyhow, expect some 20b TB modification, before and after dyno results here within a month, I'm guessing.

Kurgan

Here are my 3 favorite before and after pictures, notice how he plugged the butterfly holes and made it all smooth... great job B!

Before:


After 1:


After 2:

silverrotor

iTrader: (1)

Is their any drawbacks to doing the TB Mod? I've been wanting to do this for awhile but I want to know the Pros & Cons.

BDC

Quite honestly, Silverrotor, I haven't noticed any drawback at all. The one thing I did have to do was modify my throttle pumps a bit on my Haltech setup, but other than that it's all pro's all the way around. I've put alot of thought into this and can only see a throttle/accelerator pump issue rise but I'm not certain of it. From what I can tell, it's beneficial across the board.

B

silverrotor

iTrader: (1)

I'm not sure what throttle pumps are?

Is this for an N/A. Mine Is a Series IV.

Did you connect the engine hose to the BAC after the removal of the Thermowax?

So far this mod sounds very enticing. But has this effected your Idle or anything like that?

BDC

It'll work fine for an NA. As far as removing the thermowax and the coolant lines, you can either route a new hose directly from the back of the water pump to the rear iron housing or you can plug both ends and be done with it (preferred).

Yeah, the modification affected my idle in that I had to turn it down as it suddenly jumped from 700rpm to 1500rpm. =)

B

BDC

One more thing -- A throttle/accelerator pump is a function of an EFI system that bumps up injector duty cycle for a split-second during the time there's a heavy transition on the throttle from off-throttle to on-throttle condition. A burst of fuel is sent in to keep the mixture within operating ratios per the blast of air that the engine all the sudden sucks in. The throttle body modification I do (and the ones that other DIY'ers do that remove the secondary set of plates and shaft) change the off-to-on throttle characteristics; that "blast" of air I mentioned a second ago is shorter in time duration yet substantially stronger. The original secondary set of plates are meant to make that same throttle transition a nice, smooth, 'ramp-up' instead of a spike that's produced from the modification (and further exacerbated by my own porting and re-shaping job).

B

B

silverrotor

iTrader: (1)

Thanks BDC for taking the time to answer my questions. I may very well do this mod after I Install my Pineapple Sleeves.

user 84205

Just my 2 cents...

My mech just did his for his T51R sideported . I guess the normal bore is 3mm, and you can bore it to 4mm, and he did his to 5mm. DAMN! thats all I can say, there is like no metal between the the three spaces. Im curious of how good it will be when he gets his back in....

Jason
www.jt-imports.com

BDC

Yep. I've considered doing that, too, but there's just not very much metal there at all. I figure this mod is worthwhile. Besides, the TBody is plenty big enough in my opinion.

B

setzep

This Devcon that you are talking about, it is the same a JB Weld or can it be used the same? I'd just hate to have a chunk of that stuff find it's way into my engine. Also what is the bit/bits of choice when grinding away the material?