What can you tell me about the 74mm TB?
 

I am working on my 996 turbo.

I realize the 986 and 996t share the same throttle body, 68mm
part number 986 605 115 01

Then I saw a 74mm throttle body from a 2.7 boxster, but all my part references show the same number for all 986 boxsters.

So does the 74mm come on the 987?

If so, are they interchangeable?

Thanks!

my understanding is that 996, 997, and cayman/3.4 987 boxster tbs are all interchangeable and 74mm ID. tt runs a smaller tb because the air is compressed and you don't want to uncompress it by increasing the pipe/tb diameter.

interesting... it seems if you buy an IPD plenum they say you need to use the 74mm TB, but I'm wondering if the 74mm TB is a direct bolt on.

My 996 is running 1.55 bar on bigger turbos, so I'm not worried about de-compressing. :)

Welcome, it's a popular mod discussed quite frequently here for rather cheap. About 20 or so hp by adding the 74mm TB+ 997 Distribution-T and 987 Air intake box. I'm about to embark on that mod myself.

I realize that. I'm not working on a 986 so I'm trying to understand if the 74mm TV will work with my oem plenum.


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Is there dyno data available to support that?

What can you tell me about the 74mm TB?
 

Seems that I have found my answer. The 74mm TB which is a 997 part number does not work on the 996 turbo oem plenum.

Sort of sad since the cost of the 986 part number is almost triple that of the 997.

As JFP said... Even in the highly modded 996t world I haven't seen convincing enough data to drop that much money into buying the nearly 1000 plenum to make it work on my car.

I make 700 to wheels with the small 68mm TB. I just figured if it was cheaper to get the 74mm is give it a shot since I have to replace the TB anyway.

Last question, in the 986 community, do you guys find TB failure common?





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Could you elaborate a bit more, Please..?

On my 996 turbo not a boxster.


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I have dyno'd my last S before and after the 74mm throttle body, 996 plenum and larger MAF to tb intake. It gave a little over 5bhp.

That is more inline with what I would expect.

I don't have a previous dyno number to compare my added hp from the mod Lapister listed, but it's way more then 5 hp. EDC didn't list the mod Lapister listed, it's 20 HP on my car at the least.

If you add in exhaust system, remap then the total increase was 20-25bhp but the throttle body and plenum alone was just over 5bhp. All with before and after on dyno. The butt dyno always felt stronger to me too but the reality is it's not as much as you feel.

He didn't just list a TB and plenum change he also listed the 987 air box. You changed to a larger MAF housing, even with a tune I believe that's a mistake. It's way more then 5 hp.

I think you keep confusing my cars and listing things which I haven't done! I have had 2 Boxsters both modded, but both different. One is a 550 with the standard 987 airbox and the other an early S.

I did the most work and dyno runs with the S. Mods as in my sig and posted previously ie no MAF change or 987 airbox and it totalled 20-25bhp.

As I mentioned, the TB with intake in isolation gave about 5bhp.

You don't have the same mod as Lapister posted. You can not compare what you did to what I did, they are not the same. I misinterpreted what JFP quoted you on, you listed larger MAF to TB pipe.

I'll stick by this mod gave the car way more then 5 hp gain. Even the 2004 550 Spyder had a 6 hp gain with just the 987 air box.

I've run a 2010 style Camaro SS and there was nowhere the Camaro could pull away from my Boxster. A 2010 Camaro SS has a ptwr of 0.1091983556 and in order to set with that, a 986 Boxster would need a 25 hp gain. My intake upgrade was done meticulously, not just thrown together.

Of course the mods are not exactly the same as the other poster but given that nobody else seems willing to post up before and after dyno's or simply hasn't done it then I put my data up as a point of interest for comparison. It's not the be all and end all but at the end of the day I am not making these numbers up or telling you how it feels. I am just showing what those mods mean. My dyno plots show 5bhp or thereabouts for the intake, plenum and throttle body.

Nobody is questioning your intake. I'm sure every home DIY'er has got largely the same thing just made a slightly different way. Mine was just simple aluminium tubing and 4 ply silicone hose. I'm sure yours like mine is not using some fancy engineering computer program to test for optimum flow etc.

I wouldn't read too much in to the power and weight of other cars because if you go that far then you might as well consider diff ratios and gearing etc.

I wouldn't doubt your numbers, you didn't really do anything to help the car breath better using the stock 986 air box. You're probably lucky it gave you any hp increase.

This is what I would expect as well. I don't see the stock intake, TB, and plenum as a significant restriction with stock displacement. Unless you add 3.4L the result will just be a narrowing of the torque curve. Maybe a few Dyno ponies above 6k rpm but overall slower lap times on a race track. Less than ideal results.

I'll have to disagree with that. The 3.2l will benefit from this mod. I have first hand experience with the mod, the cars pulls strong throughout the rpm range. If anything his dyno shows the results of when you don't fully execute the modification.

I don't know much about 996T's, but you're the second person in a week contacting me about buying a 68tb to put on their 996T. The other guy made it sound like it's common to the 68TB in the 996T. Maybe the heat gets to them?

I've posted the plots a few times before so I won't post again but for all the mods I did each one showed a power and torque gain after about 3500rpm. It's not just a peak last 1000rpm gain.

Ha, I was the one that told the other guy about you!

I'm not sure the 996 guys suffer failures often, but they do. I'm not 100% positive that's my problem but its very similar to what happened last time.

The 996 turbo part number is the same as the 986 part number.

They are all the same. Sadly on the 996 turbo, the plenum is very different from any of the NA motors, so it's not as simple as buying the 997 plenum for 50 bucks!

Gotta buy the stupid IPD for 900. Even at big hp levels the plenum/TB combo is "said" to make 20 to 30 whp. And THAT is for guys pushing 700 to 900 hp.

I have a hard time thinking it would be anywhere near that for the NA folks, but like I said I don't know.

I apologise in advance for the hijack, but I have to question this statement. looking at EDCs before and after dyno posts for his mods (and those posted by ipd which I typically try not to reference as they are biased) the tb/plenum change doesn't appear reduce torque at anyplace in the rpm range, so the statement about narrowing the torque curve is incorrect from my interpretation. I too wondered about the loss of low load intake tuning due to the opening of the intake path, but everything I've seen seems to indicate otherwise. *** edit to add that edc appears to have beat me to this ***

I know I've been involved in this dialog about intake modifications, but have never made any claims about hp increases on my car. I too think claims of 20 hp are optimistic when unsupported. a quick note about the ability of mods to affect hp, however (porsche hp figures, summary of changes upon review of porsche parts catalog):

2000 S: 250 hp.

2003 S: 258 hp - intake tube change, head and cam change (valves and lifters same size) ecu change to 7.8 (but no variocam+ until 2007 with the change to 3.4).

2004 Anniversary: 266 hp - airbox change.

2005 987 S: 280 HP - exhaust change, intake plenum change.

uncertain what role factory tuning played on these hp increases.

at this point Porsche retired the 3.2 and started using the 3.4 in the boxster. note that 280 is the same power:displacement ratio as the 911 3.4, so it is like Porsche gradually removed the restrictions from the boxster engine over 5 years.

I figure we should be able to find that same 30 hp using the same approach Porsche did (perhaps even using the same oem parts). we might even be able to get more if we are willing to do things Porsche wasn't (due to liability concerns?) -larger tb 5 hp proven (but causes a twitchier throttle) udp 5 hp proven (but reduces alternator output) tune 5 hp proven (but can affect engine longevity). of course these gains may not be additive, but it is fun to think that 45 hp might be boltonable (new word for the day).

hijack over!

I don't know much about the turbo plenums, but what about this one?

07 08 09 Porsche 911 997 Turbo Air Intake Distributor Tube 99711021570 | eBay

Pretty sure that's for a 74mm tb isn't it?

You know what though... We had a similar discussion on our PCA region's facebook page. I don't know the best way to link to it...but here is a copy paste.

Installed my 82mm PORSCHE GT3 plenum & throttle body. 20% increase in power BABY !!!! Can't wait for the B&B exhaust system I order to come in ...
David Cavazos's photo.
David Cavazos's photo.
Like · Comment · 1042
10 people like this.

Michael Baynton 20% increase?
March 2 at 8:24pm · Like · 3

Sudhi Ranganathan
March 2 at 8:55pm · Like · 1

David Cavazos YES SIR!
March 2 at 9:15pm · Like

Michael Baynton Is there a mini turbo tucked inside?;)
March 2 at 9:21pm · Like · 1

Sudhi Ranganathan 2 Hamsters with 10% each in a wheel is embedded inside that huge plenum tongue emoticon
March 2 at 9:37pm · Like · 1

Philip Rogers Wow, 300hp to 360hp just from a plenum and throttle body? I need to buy these magical parts.
March 2 at 10:23pm · Like · 3

David Cavazos No 295 to 350 .. K&M Filter, GT3 82mm Plenum and Throttlebody and B&B exhaust

987 Competition Cayman 3.4L Plenum: HP Gains 20+ / Torque Gains 18 Requires upgrading factory 74mm Throttle Body with 997 GT3 82mm Throttle Body...See More
David Cavazos's photo.
March 2 at 11:26pm · Edited · Like

David Cavazos Double boom !!!
David Cavazos's photo.
March 2 at 11:08pm · Like · 1

Alan Simmons wow
March 2 at 11:45pm · Like · 1

Sudhi Ranganathan David Cavazos - How about a dyno result once you are done with all these mods?
March 3 at 6:41am · Like · 1

David Cavazos Once all is installed I will.. I plan to
March 3 at 7:55am · Edited · Like

Philip Rogers Just don't be disappointed with the discrepancy between real world whp and marketing.
March 3 at 8:55am · Like · 1

Michael Baynton 20HP? Sure. 20% bump? Hmmmm
March 3 at 9:01am · Like · 1

David Cavazos You mean to tell me all this years, the people that have been adding bigger carburetors, larger intake manifolds, larger fuel pumps after market performance products but got no results ?

Your probably to type a persons that seen the white & gold dress. ...See More
March 3 at 9:19am · Like

Philip Rogers Who said anything about not getting results?
March 3 at 9:35am · Like

Robert Conyers Jr Have you dynoed your car in its current state? To gain 55hp on a NA engine of 3.4L from exhaust (minus headers, and air inlet mods) is a lot. That means your car is being choked to Hell in its current state. I'd say a maybe 25-30....only way to know is before and after on the dyno or before and after on the drag strip (trap speed).
March 3 at 10:03am · Like

Sudhi Ranganathan You know what David Cavazos - If after you put your mods you feel good'er when you drive, it's priceless. I suppose I will take back the Dyno recommendation. You drive on the roads and on track - not on a dyno smile emoticon If it feels good, it's good. That's all!
March 3 at 11:05am · Like · 2

Robert Conyers Jr Do a before and after dyno David. That's good data for everyone to have. That's how we all learn what works and what doesn't. Just like on my Corrado. Neuspeed advertised X amount of HP gain. When I went to the strip, consistently the factory airb...See More
March 3 at 6:10pm · Like

Brad Roberts We regularly see 50hp gains with this plenum/Cayenne V8 throttle body, real headers and using 997 3.8 Cats and high flow mufflers, but.. we tune for torque, so typically they end up around 340hp and an awesome torque curve. Someone above said: "choked ...See More
March 3 at 6:41pm · Like · 3

Robert Conyers Jr Nice! If big gains like that can be had, that will be awesome. I always wondered if the cars are really restricted exhaust/intake wise. I haven't changed anything on my 997.1s, but I'm curious on what real world improvements would be had from intake, exhaust & hi-flow cats.
March 3 at 7:22pm · Like · 1

Taylor Stilovich Brad Roberts, who is we?
March 3 at 9:25pm · Like

Brad Roberts Taylor, I use a custom tune on each car by a guy who handles 20-30 pro cars in Tudor. He tunes all the BGB cars.. I had him tuning for me before he met BGB. Custom tunes, not BS generic tunes.
March 3 at 11:37pm · Like

Taylor Stilovich No I meant who or where do you work. I mean no offense at all I'm pretty new to Pca so I don't quite know who is who.
March 3 at 11:39pm · Like

Taylor Stilovich I guess I don't who or what BGB is.
March 3 at 11:40pm · Like

Brad Roberts BGB races Caymans professionally.. and has for years.
March 4 at 12:36am · Like

Scott Carlberg
Scott Carlberg's photo.
March 4 at 1:36am · Like · 1

David Cavazos Brad, thank you for proving my point 😎
March 4 at 6:59am · Like

Michele McMaster Hart So..David - when is your next track event so we can all go whip your ass on the track? Or you can prove everyone wrong. wink emoticon
March 4 at 7:12am · Like

Taylor Stilovich I'll admit it does seem like a big increase for what the mods are. Although I suppose it does depend on what restrictions are present from the factory. I was under the impression that porsche had the cars pretty wrung out for naturally aspirated ones.
March 4 at 7:22am · Like · 1

Robert Conyers Jr David, Brad did say with the addition of "real headers" & the car being tuned for all of those mods he saw that much gain. When are you getting tuned? . Tuning can make or break the car. . I want to hear the exhaust when you get it on. Will it be here in time for cars & coffee?
March 4 at 7:58am · Like

Michael Baynton David, I'm rooting for you, too. But I do want to see corrected before and after dyno pulls to substantiate a crank HP increase from 295 to 350-ish.
March 4 at 8:50am · Like

David Cavazos Okay half empty glass kind of guy lol I'm waiting for the exhaust to come in and I will
March 4 at 11:07am · Like

Colt Klatt Excited for you brotha. Haters gonna hate
March 4 at 11:44am · Like

David Cavazos The exhaust won't be in till Next week .. I've installed the throttle body and plenum.. The coilovers are next .. Then Roll Bar, seats, belts ... On and on ..
March 4 at 11:52am · Edited · Like

Robert Conyers Jr Oh ok....Awesome anyway!....New parts are always exciting. Which coilovers did you end up going with? Are you having someone do it or doing it yourself? Let me know if you need some help. You are going to make me buy something for my car if you keep this up. LOL
March 4 at 11:56am · Like · 1

David Cavazos Should consider exhaust or bypass .. Victor Verissimo 's car exhaust notes are a symphony .. He did a bypass I believe
March 4 at 12:02pm · Like · 1

Robert Conyers Jr Yea, I heard it. Sounds awesome. He has the Fiskers or whatever they are called. I thought about doing that and having the exhaust minus the headers ceramic coated. I hate seeing the rusty/corroded exhaust.
March 4 at 12:13pm · Like · 1

Brad Roberts Video showing one of the 987 3.4 340hp conversion cars we did. We are testing a new launch control module in this video.http://youtu.be/42QJFFwdUqU

PCA OCR Autox 4/17/11 - BSP Boxster
This video was uploaded from an Android...
YOUTUBE.COM
March 4 at 12:22pm · Edited · Like · 2

Robert Conyers Jr Brad, nice! What rpm was it holding at?
March 4 at 12:32pm · Like

Brad Roberts I believe I had it set for 2800rpm, right before Variocam kicks in. It's programmable. I raise it lower it as the tires and surface warm up. In another video you can hear the flat shift feature. No lift ignition interrupt upshift like a Cup car.
March 4 at 12:34pm · Like · 1

Philip Rogers Brad what are they putting down to the wheels? 340 = 305whp or so given an average 10% loss?
March 4 at 1:45pm · Like

Brad Roberts I use 15%
March 4 at 2:02pm · Like

Thanks, but here is the issue. This is the IPD 996t plenum I couldn't find the oem pic...but this is what the vacuum stuff needs to resemble.

http://www.911tuning.com/custimages/...01145637AM.jpg

I see now. Here is a oem picture if you need one.

http://c1552172.r72.cf0.rackcdn.com/227204_x800.jpghttp://c767170.r70.cf2.rackcdn.com/G99611021571.jpg

Search 99611021571 - 99611021571 - Turbo Intake Plenum - ES#1483665

Crazy there is no 74mm option for you besides the IPD piece.

Maybe you could have someone with a 3D printer do one for you. There is a member on the forums here doing some 3D printed plenums to get a 74mm tb on the Boxster and keeping it pretty close to the factory location.

http://986forum.com/forums/diy-project-guides/55966-intake-plenum-911-throttle-body.html

Sorry, but I think it is a massive leap of faith to assume that the HP increases happened only because of a change in some bolt on intake components.

I agree; any idea where the hp came from? Porsche was able to increase by 30 hp; the only significant, impactful changes I can find are detailed in my post.

Curious, did Fabspeed fudge the numbers on this video? They ended up with a 27 hp gain with new exhaust, slight intake mod and tune.

<iframe width="640" height="360" src="//www.youtube.com/embed/WN_h9juITLk?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>

Protip: Sometimes marketing folks lie. :D

I was wondering. They have in the description it was at the crank. Don't they have to put some kind of variable in the system when figuring the crank hp when doing the dyno from the wheels?

On my dyno jet a well serviced 3.2S will put down 230HP in stock form.

We wear our dynes out here (we have two engine dynos and a chassis dyno) doing development. You learn a lot over time, but most of what you learn is that most dyno operators are completely lost.

Call your favorite supplier of go fast goodies and ask the first person who answers the phone what the 4 strokes of a 4 stroke engine are. You'll be transferred 2-3 times before anyone can tell you. Guaranteed.

Most of what people do to these engines result in LESS net power.

I have 996TT here now that one of these "tuners" and their products killed. They installed larger intake tubing without ensuring the suspension didn't contact the larger tubing with the car on the ground. Up in the air there's a ton of clearance, but on the ground the suspension punctured the tubing, generating debris which passed through a 3,000 dollar turbo and then sent that debris into the engine. The result is a 40 thousand dollar lesson being learned by the owner.

That sort of sounds like an install error. Although I do know of some inlet piping that previously was sold as a ready to fit product only later to realize it needed to altered to make work.
I feel that is a totally different subject. I originally started this thread based on a question about fitment of a throttlebody. I can see how adding a bigger throttlebody to a Boxster platform is a controversial issue. Maybe I'm a little sensitive because I have a 996t but for sure not all tuners are created equally.


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The larger TB will usually hurt torque and only gain marginal HP, but over a very narrow power band. This is due to the intake plenums of the Boxster engine, as well as runner characteristics.

All combinations will vary in performance gains.

Finally got some time to compare my good v bad throttle body just FYI. https://vimeo.com/131321825


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That ending line is your saving grace. I can tell you without a doubt, cross my heart and hope to die, that my intake mods has made my car a beats. It has not lost any torque or a narrow in power band. My car is flat out hauling through the whole RPM range. I don't need a dyno to tell me the car has gain a substantial performance gain. It flat gets with it. Do it right and you will be rewarded.