Throttle Body Size...power gains?

cuco · 07-03-2013, 02:49 PM

I found this interesting site that calculates the TB size according to engine size/rpm/bore/stroke...etc...this helps determine the correct TB size for engine application, even takes into account if engine has tuned exhaust and cam.

Here's the link:
http://dairally.net/daihard/chas/Mis...8&Button=Reset

I know there is a lot of debate about the power gains, if any, on boring the TB to 79mm (like the Dinan TB). I also found this other site that explains the science behing TB size selection and why sometimes a bigger TB size doesn't yield any gains.

http://www.musclemustangfastfords.co...t/viewall.html

From what I've read, it looks like no one can label that 'x'mm increase in TB size will yield 'x' amount of net hp. The TB power gains depend more on the intake/exhaust CFM capacity, intake air pressure, cam timing and other factors.

Enjoy

SDemetris · 07-03-2013, 05:33 PM

If someone wants to figure out the ideal number for our car, I have an extra tb and a lathe so I could bore one out and see if it makes a difference. I probably would just be gains according to the dyno, but it wouldn't take long to set that up

cuco · 07-03-2013, 07:17 PM

I played with the TB calc for a while and 79mm looks like a good number. My gut feel tells me that a stock car won't see much improvement cause of the intake and exhaust restrictions, but I'm pretty sure there will be a difference felt on cars with headers, 3 stage inake and tune. Also, Im sure Dinan did some research before coming up with that number. Here is a screen shot of the calculated results considering that the engine has a modded exhaust and tuning.

The values at the lower right represent the ID size in mm. The results represent different calculation methods.

andrey_gta · 07-03-2013, 09:13 PM

Somewhat cheap to check.

Buy salvaged TB
Maxbore.com

Under 350 total cost

SDemetris · 07-03-2013, 09:54 PM

I got one attached to my three stage. The thing Im worried about is getting an error or something because i would have to take it apart to get the throttle off the bore the whole way through

07tundra · 07-03-2013, 10:36 PM

[QUOTE=SDemetris;14266684]If someone wants to figure out the ideal number for our car, I have an extra tb and a lathe so I could bore one out and see if it makes a difference. I probably would just be gains according to the dyno, but it wouldn't take long to set that up[
Never mind

07tundra · 07-03-2013, 10:42 PM

Sorry guys I didn't see this was under na. I just hit new post and it was interesting so I posted. Sorry again!

mapleridge · 07-04-2013, 12:31 AM

as you guys know me and throwing money at my n52b25. I would probably try this too.

smellthebeans · 07-04-2013, 06:08 AM

Quote:

Originally Posted by andrey_gta

Somewhat cheap to check.

Buy salvaged TB
Maxbore.com

Under 350 total cost

Wow...compared to the $990 Dinan product.

cuco · 07-04-2013, 07:32 AM

Quote:

Originally Posted by SDemetris

If someone wants to figure out the ideal number for our car, I have an extra tb and a lathe so I could bore one out and see if it makes a difference. I probably would just be gains according to the dyno, but it wouldn't take long to set that up

If you bore it out, a new, bigger butterfly would have to be made too. I would also compare the ID of the intake hose that connects to the TB. If they matched then I would polish the ID of the TB after boring.

Quote:

Originally Posted by andrey_gta

Somewhat cheap to check.

Buy salvaged TB
Maxbore.com

Under 350 total cost

I checked maxbore.com and it looks like he does the boring/tapering, new butterfly, polish etc.

GTKrockeTT · 07-05-2013, 01:17 PM

i have a spare throttle body and plan on having George @ maxbore bore it out. don't expect any noticeable gains, but filing this in the "might as well" category...

SDemetris · 07-05-2013, 01:47 PM

Quote:

Originally Posted by cuco

If you bore it out, a new, bigger butterfly would have to be made too. I would also compare the ID of the intake hose that connects to the TB. If they matched then I would polish the ID of the TB after boring.

Actually that is not necessary in our cars since the tb is open all the time. we dont need the plate at all in reality. but for every other car that isnt a n52/n55, yes that would have to be done

GTKrockeTT · 07-06-2013, 12:08 PM

Quote:

Your TB uses a system to hold the butterfly in place that I cannot duplicate.
The TBs I bore use screws and a smooth faced butterfly. Your TB uses slots in the butterfly and what seems like very special clips to hold the butterfly in place.
Sorry I can't work on it.

George
www.maxbore.com

Looks like I get to save my money.

Tim603 · 07-06-2013, 04:53 PM

Quote:

Originally Posted by GTKrockeTT

Looks like I get to save my money.

lol figures

cuco · 07-06-2013, 05:02 PM

Quote:

Originally Posted by GTKrockeTT

Looks like I get to save my money.

Hmm, so it requires some additional machining and fab. Can anyone with a spare TB take it apart and take pictures of the butterfly assembly?

nate5ks · 07-06-2013, 07:49 PM

Quote:

Originally Posted by SDemetris

Quote:

Originally Posted by cuco

If you bore it out, a new, bigger butterfly would have to be made too. I would also compare the ID of the intake hose that connects to the TB. If they matched then I would polish the ID of the TB after boring.

Actually that is not necessary in our cars since the tb is open all the time. we dont need the plate at all in reality. but for every other car that isnt a n52/n55, yes that would have to be done

The butterfly serves as a backup in case you have a valvetronics motor failure. I forgot to connect the valvetronic motor wiring after changing my vcg and didn't notice it for a week.

Lifted07Duramax · 07-06-2013, 07:51 PM

Quote:

Originally Posted by 07tundra

Sorry guys I didn't see this was under na. I just hit new post and it was interesting so I posted. Sorry again!

Greedy motherFer. Already wanting more power lol

07tundra · 07-06-2013, 09:29 PM

Me wants more!! I think it wld be worth looking at

freon480 · 07-06-2013, 10:16 PM

no need to upgrade a throttle body on a n/a engine unless you have internal upgrades to support. you will see no power gain. it will feel different since it is the throttle you are messing with
a but there is no need to introduce a larger volume if your engine is not calling for it. if you had to drink a mcdonalds milk shake from a cup would you be able to get more out with a straw with a hole the size of a half dollar? would you be able to get more tasty beverage in faster? or would you have to pull harder and most likely get less. i cant think of one na car bmw or others ive worked on where the throttle body unlocked power unless compression was increased. s

cuco · 07-07-2013, 07:29 AM

Quote:

Originally Posted by nate5ks

The butterfly serves as a backup in case you have a valvetronics motor failure. I forgot to connect the valvetronic motor wiring after changing my vcg and didn't notice it for a week.

Hmm, im not familiar with this, I'll have to dig in. So is the buttefly open all the time when the valvatronic motor is connected?

Eagle1oh7 · 07-07-2013, 01:50 PM

Quote:

Originally Posted by freon480

no need to upgrade a throttle body on a n/a engine unless you have internal upgrades to support. you will see no power gain. it will feel different since it is the throttle you are messing with
a but there is no need to introduce a larger volume if your engine is not calling for it. if you had to drink a mcdonalds milk shake from a cup would you be able to get more out with a straw with a hole the size of a half dollar? would you be able to get more tasty beverage in faster? or would you have to pull harder and most likely get less. i cant think of one na car bmw or others ive worked on where the throttle body unlocked power unless compression was increased. s

Wouldn't a wider TB combined with a tune be beneficial though?

cuco · 07-07-2013, 02:04 PM

Quote:

Originally Posted by Eagle1oh7

Wouldn't a wider TB combined with a tune be beneficial though?

go over post #1, #3 and click on the links, I don't want to turn this thread into a "is it beneficial or not" discussion.

07-03-2013, 02:49 PM	#1
cuco First Lieutenant 49 Rep 318 Posts Drives: 85 BMW R80 Join Date: May 2012 Location: Cincinnati OH iTrader: (1)	Throttle Body Size...power gains? I found this interesting site that calculates the TB size according to engine size/rpm/bore/stroke...etc...this helps determine the correct TB size for engine application, even takes into account if engine has tuned exhaust and cam. Here's the link: http://dairally.net/daihard/chas/Mis...8&Button=Reset I know there is a lot of debate about the power gains, if any, on boring the TB to 79mm (like the Dinan TB). I also found this other site that explains the science behing TB size selection and why sometimes a bigger TB size doesn't yield any gains. http://www.musclemustangfastfords.co...t/viewall.html From what I've read, it looks like no one can label that 'x'mm increase in TB size will yield 'x' amount of net hp. The TB power gains depend more on the intake/exhaust CFM capacity, intake air pressure, cam timing and other factors. Enjoy __________________ Airhead//Caffeine//Junky//Beemer//Fan
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07-03-2013, 05:33 PM	#2
SDemetris FSAE Dude 68 Rep 759 Posts Drives: E90 328xi Join Date: Jul 2012 Location: Pittsburgh, PA iTrader: (0)	If someone wants to figure out the ideal number for our car, I have an extra tb and a lathe so I could bore one out and see if it makes a difference. I probably would just be gains according to the dyno, but it wouldn't take long to set that up
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07-03-2013, 07:17 PM	#3
cuco First Lieutenant 49 Rep 318 Posts Drives: 85 BMW R80 Join Date: May 2012 Location: Cincinnati OH iTrader: (1)	I played with the TB calc for a while and 79mm looks like a good number. My gut feel tells me that a stock car won't see much improvement cause of the intake and exhaust restrictions, but I'm pretty sure there will be a difference felt on cars with headers, 3 stage inake and tune. Also, Im sure Dinan did some research before coming up with that number. Here is a screen shot of the calculated results considering that the engine has a modded exhaust and tuning. The values at the lower right represent the ID size in mm. The results represent different calculation methods. __________________ Airhead//Caffeine//Junky//Beemer//Fan
	Appreciate 0 Quote

07-03-2013, 09:13 PM	#4
andrey_gta Brigadier General 327 Rep 4,040 Posts Drives: 130i coupé ;) Join Date: Nov 2011 Location: Bimmerpost iTrader: (1) Garage List 2008 BMW 128i [10.00]	Somewhat cheap to check. Buy salvaged TB Maxbore.com Under 350 total cost __________________ 128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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07-03-2013, 09:54 PM	#5
SDemetris FSAE Dude 68 Rep 759 Posts Drives: E90 328xi Join Date: Jul 2012 Location: Pittsburgh, PA iTrader: (0)	I got one attached to my three stage. The thing Im worried about is getting an error or something because i would have to take it apart to get the throttle off the bore the whole way through __________________ 2007 TiAg 328xi: AA Tune, AFE intake, Full exhaust, 335xi Brakes, H&R RSB, UUC FSB, H&R Sports, Billy Sports...BBS SR 17x8 1985 Gazelle Beige 325e: Poly everything, e24 3.25 LSD, 225 lb weight reduction, Corbeau FX1, Shifter machined by me, roll bar, harness, all the other goodies. My "Racecar"...15x7 BBS RA
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07-03-2013, 10:36 PM	#6
07tundra Lieutenant Colonel 128 Rep 1,524 Posts Drives: 8.1L Chevy 2500hd Join Date: Jan 2012 Location: New Mexico iTrader: (9)	Rb [QUOTE=SDemetris;14266684]If someone wants to figure out the ideal number for our car, I have an extra tb and a lathe so I could bore one out and see if it makes a difference. I probably would just be gains according to the dyno, but it wouldn't take long to set that up[ Never mind Last edited by 07tundra; 07-03-2013 at 10:45 PM..
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07-03-2013, 10:42 PM	#7
07tundra Lieutenant Colonel 128 Rep 1,524 Posts Drives: 8.1L Chevy 2500hd Join Date: Jan 2012 Location: New Mexico iTrader: (9)	Sorry guys I didn't see this was under na. I just hit new post and it was interesting so I posted. Sorry again!
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07-04-2013, 12:31 AM	#8
mapleridge Banned 166 Rep 2,638 Posts Drives: E90 N52 AT Join Date: Apr 2011 Location: Vancouver, BC iTrader: (4)	as you guys know me and throwing money at my n52b25. I would probably try this too.
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07-05-2013, 01:17 PM	#11
GTKrockeTT Second Lieutenant 23 Rep 198 Posts Drives: Join Date: Sep 2007 iTrader: (1)	i have a spare throttle body and plan on having George @ maxbore bore it out. don't expect any noticeable gains, but filing this in the "might as well" category...
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07-06-2013, 09:29 PM	#18
07tundra Lieutenant Colonel 128 Rep 1,524 Posts Drives: 8.1L Chevy 2500hd Join Date: Jan 2012 Location: New Mexico iTrader: (9)	Me wants more!! I think it wld be worth looking at
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07-06-2013, 10:16 PM	#19
freon480 12:34 70 Rep 606 Posts Drives: 06 E90 325xi Join Date: Oct 2011 Location: wastechester NY iTrader: (2)	no need to upgrade a throttle body on a n/a engine unless you have internal upgrades to support. you will see no power gain. it will feel different since it is the throttle you are messing with a but there is no need to introduce a larger volume if your engine is not calling for it. if you had to drink a mcdonalds milk shake from a cup would you be able to get more out with a straw with a hole the size of a half dollar? would you be able to get more tasty beverage in faster? or would you have to pull harder and most likely get less. i cant think of one na car bmw or others ive worked on where the throttle body unlocked power unless compression was increased. s __________________ pics of my e90 lci conversion--> http://www.e90post.com/forums/showthread.php?t=753713 follow me on instagram :freon480 https://www.facebook.com/media/set/?...7036780&type=1
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