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[jagojon3]

I still have the stock z6 TB on my setup, have a feeling it is a major restriction in my intake. Stock Z6 IM. How much of a difference have you guys noticed with an upgrade to a port matched IM and 60mm TB? I have these laying around somewhere, just gotta find em.

Check out this pic of my high cam fuel map, it drops off more dramatically up top than previous setups I've done. It's tuned to run around 12:1 at low boost and 11.5:1 at higher boost. Haven't revved it over 7200

[chris]

Track times on bone stock d16's with ported manifold/b series oem throttle bodies were .2-.3 tenths of times with 2-3 mph gains. No tuning. I did this testing back when when I was still in college and did not have access to afford dyno's etc. If stock motors react in a positive manner then you should see gains well beyond what is found on a stock motor. These were in my opinion crude version of port work as they were done when I first started. Excessive material must be removed from the d16z6 manifold for it to perform. The nice part about the d16z6 manifold is that its plenum design allows for alot of porting blending due to the smooth/straight angle.



You will see increased throttle response also this is something that is desirable when you being to upgrade into the world of larger turbos.


Also if you ever plan on upgrading your camshaft a 60mm throttle body which already isnt enough for a boosted motor will again become a major restriction. Increased valve lift will allow a much larger throttle body again gaining more power again and throttle response with both the combination of both the camshaft/throttle body should net gains once again.



You will also see the powerband want to carry to a higher rpm.

[QikEnuF]

Random question, at what point does a TB get too large diameter/flow wise for a given application?  Is there a noticeable drop in throttle response?  Or it just stops gaining?

[bgdriver]

A throttle body is too big when it flows more than the engine. It will stop gaining power and decrease driveablility.

[QikEnuF]

How does the driveability decrease?

[jagojon3]

You'll lose throttle resolution.

[turbob16hatch]

i biggest fear/concern with bigger throttle bodies, not b series big but 65-70mm+ big. Is that when trying to part throttle cruise it will be real jerky and almost imposible to just cruise.

i think there is a point where driveablity out wiegh's the performance gains. although this all comes down to personal preference and opinion. i still think stock like drivablity should be retained as far as throttle response er w/e the term is.

chris, or anyone with some good real world experience can you explain where the t-body size really starts to effect drivability?

[QikEnuF]

Does it work the same for boosted cars?  Cause at that point, don't you just shove x amount of air into the bish anyways, so the TB just loosens the restriction on how much of X air goes in at once?  Or can you still have too large of a TB on a boosted motor?

[dvst8r]

Does it work the same for boosted cars?  Cause at that point, don't you just shove x amount of air into the bish anyways, so the TB just loosens the restriction on how much of X air goes in at once?  Or can you still have too large of a TB on a boosted motor?

You can on the vacuum side, if it is a street driven car, not so much on the boost side.

[chris]

i biggest fear/concern with bigger throttle bodies, not b series big but 65-70mm+ big. Is that when trying to part throttle cruise it will be real jerky and almost imposible to just cruise.

i think there is a point where driveablity out wiegh's the performance gains. although this all comes down to personal preference and opinion. i still think stock like drivablity should be retained as far as throttle response er w/e the term is.

chris, or anyone with some good real world experience can you explain where the t-body size really starts to effect drivability?

I have run 70mm throttle bodies on stock d16z6 and never had problems with driving issues. This again is another internet rumor. The Hond amanifold can only accept to a certain point regarding throttle body size due to iacv spacing in the manifolds


Again I have more testing with throttle bodies than most people will in a lifetime and JERKING I have no idea what concept that would apply too. The d series motors are horribly tuned down from the factory so that the larger B series motors can shine in the more expensive chassis.


Honda cylinder heads flow well beyond what other brands due and this applies to intake manifolds also.



If you guys ever sit on a flowbench you will come to the conclusion that everything you read on the internet is pretty much bullshit. Volume kicks ass.

[98vtec]

your fuel curve typically has a close relationship to the torque curve on a dyno graph.  I'm sure you could use a bigger throttle and gain more top end.  I dont have any true experience with that tho, just speculation.

[crxvtec91]

I am gong to be running a 74mm tb on my built Z6!

[92CXyD]

i biggest fear/concern with bigger throttle bodies, not b series big but 65-70mm+ big. Is that when trying to part throttle cruise it will be real jerky and almost imposible to just cruise.

i think there is a point where driveablity out wiegh's the performance gains. although this all comes down to personal preference and opinion. i still think stock like drivablity should be retained as far as throttle response er w/e the term is.

chris, or anyone with some good real world experience can you explain where the t-body size really starts to effect drivability?

I have been driving on my d16z6/y8 with one of Chris's 70mmTB and at idle on up w/0 the S/C engaged and I had no idling, drivablity, or acceleration issues. I DD my car whith no issues.

BTW with the S/C engeged the TB/spacer/port matched z6 mani made a huge difference. ;D :yes:

[turbob16hatch]

I have run 70mm throttle bodies on stock d16z6 and never had problems with driving issues. This again is another internet rumor. The Hond amanifold can only accept to a certain point regarding throttle body size due to iacv spacing in the manifolds

Again I have more testing with throttle bodies than most people will in a lifetime and JERKING I have no idea what concept that would apply too. The d series motors are horribly tuned down from the factory so that the larger B series motors can shine in the more expensive chassis.

Honda cylinder heads flow well beyond what other brands due and this applies to intake manifolds also.

If you guys ever sit on a flowbench you will come to the conclusion that everything you read on the internet is pretty much bullshit. Volume kicks ass.

that is some good information, but i'm still not getting the answers i guess i'm looking for. Now the 70's seem to work well as you have stated. But at what point does size become a negative factor? 75mm, 80mm, etc. i also understand you said there is a size limitation as to the location of the iacv.

[chris]

You can only go to a 68mm throttle plate on newer b series manifolds. Older b series only 65. D series only 65mm. This is why i came up with the tapered throttle spacer with centered iacv port



Now again the plenums of these manifolds can only go so large and even aftermarket manifolds the way they are designed are limited to a 70mm throttle plate from what i have seen. I believe the new skunk2 manifolds allows slightly larger.



This is the limit I have gone with b series/d series for obvious reasons. Any larger will require one off manifolds/fabrication/iacv adapter etc.


So is there a limit sure. have I bothered to go any more drastic than I have in my personal experince,NO. Im a poor white trash kid from the ghetto so i dont have money to play with one off crazy shit. My experince has been with Honda manifolds 99 percent of the time due to the price and gains I have achieved with them. The casting is beautiful compared to the aftermarket ones making porting them a dream compared to cheaper casted manifolds from Asia.



Unless your running a crazy all motor car with a .500+ lift camshaft the sizes that fit onto your standard manifolds are enough to keep both motor/driver happy. The 300 whp all motor h series car i tuned a couple years back was running 2 83-77mm throttle bodies. But again this motor ran one off cams,head that flowed into the 350 cfm range. Basically there is maybe 2-3 h series motors ever built all motor wise that can benefit from such induction.

[boosted15]

Is there a point to use a TB that is is much larger than your charge pipe though? I have 2.5" piping, would say a 65mm be more effective than a 70mm in this case?

[turbob16hatch]

That is another good point,  in a boosted application how big of a roll does throttle body size play a part vs n/a applications?

I would think that it is less important then when N/A. but i'm no expert.

[chris]

Your running forced induction trying to force that air into pee size inlets,yeah it makes a huge difference.


You will see boost sooner,more throttle response out of boost and you will shift your rpm range up allowing a more useable power range.



Its a win win and the cheapest thing you can do on the top end.

[92CXyD]

Agreed it made a huge difference I was running 10psi. on S/C setup last summer with a H23 tb redline at stock p28 setting and the car seemed fast.

Then when I put Chris's 70mm tb on with 10psi on my S/C setup it was a lot faster and I can run the engine all the way to 9k if I want to.  ;D