Performance option: Bored out stock Throttle Body

[CRZ_for_me]

So I was looking for a way to boost power and boring out the TB is always an option on just about every car. I won't go too too much into the background but different cars will respond different to boring out the TB. Basically, bigger engine = more noticeable difference. Quality of the boring and knowing how much to bore out are factors too. I came from the Corvette world and boring TB would pick up 0 whp - 5 whp. The biggest advantage was not whp but a noticeable increase in throttle response was the payoff. It cost $150 to do it in that world and it was a no-brainer mod. Ok enough of this.........

What about the CRZ? My interest was piqued when I saw the J's Racing oversize TB they sold. They gave the dimensions they used. Perfect! Now, using a reputable company such as Maxbore we can replicate the same thing for hundreds less. $575 for the J's Racing piece is ridiculous.

Here is the transcript of my email conversation with Maxbore:

Hello,

I was wondering if you bored TBs for the 2011 Honda CR-Z? It's a 1.5L but I'm not sure what the engine code is or if it is used in something else.

J's Racing sells an overbored TB for this car (one of the only mods available so far). Here is the link to a place that sells it and I'll copy and paste the excerpt.

Go Tuning Unlimited



Description:

Fits 2011+ CR-Z models
Uses OEM throttle body
Made in Japan

Expands the opening of the throttle body from 58φ to 60φ and at the butterfly from 50φ to 52φ for an increase in air flow area. Improves throttle response and overall engine power.
I have no idea what that symbol is. Maybe Japanese for millimeters? Anyways, could you bore to match these dimensions (or maybe a little more if you think it wouldn't cause a CEL)?

Response:

Hello
I can bore it. They say the bore is enlarged by 2mm over stock.
The symbol is diameter, so they bore it from 50mm to 52mm.
I bore Tbs 3 to 4mm on average, but it really depends on the casting.

I then asked how much. $125 shipped back.

So $125 or $575..........I plan on doing this when things warm up a bit. Will be interested in seeing the difference.

Maxbore site: Maxbore.com throttle body boring service

They have a great rep.

[taikahn]

Subscribed for results.

[CRZ_for_me]

I'll take before and after pics too.

[JCRZ]

Def interested in results.

[CRZ_for_me]

You know, you guys can do it too! Don't have to wait for me!

The only negative is you have to take the TB off and ship it off. Turnaround is like 3 -4 business days. So second car is kind of a must.

[GoHuskies]

Get yours back quick!

I have vacation coming up end of January so the car won't be needed for a week. If this mod really offers some better acceleration feel on the cheap I'm down!

[CRZ_for_me]

Originally Posted by GoHuskies

Get yours back quick!

I have vacation coming up end of January so the car won't be needed for a week.

I haven't sent it off yet It's been so damn cold here I haven't wanted to. I don't know if I'll meet your deadline.

If this mod really offers some better acceleration feel on the cheap I'm down!

Well, in the Corvette world it def. did. I know apples vs. oranges but this does work. It will just be a matter of whether on a 1.5L boring the TB is really worth. I don't mind spending $125 to find out. J's Racing made a TB for reason, IMO.

See my response in bold

[Stealth]

Originally Posted by CRZ_for_me

See my response in bold

Larger diameter throttle bodies work best in conjunction with some way to manipulate the a/f ratio and an enlarged intake tract (port polish is also a good finishing touch). I don't know how much difference this will make on its own, but its worth a shot...

[SS2CRZ]

Subscribed!

This information sounds very useful; as it sounds like a max bored throttle body would be a perfect fit for my newly-found knowledge on the stock intake manifold (from another thread today).

Basically, the so-called "Spoon Bigger Capacity Intake Manifold" (Plastic "Plenum" chamber) that some companies are selling for $335 (painted "Spoon Yellow, mind you...) is nothing more than a stock, OEM 2010+ Honda Fit intake manifold "chamber". The Honda part number is: 17110-RB1-000 and Bernardi Honda's price on it is $123.50

Apparently it is about a 45 minute job--a simple OEM parts swap. We're still waiting on Dyno numbers from two forum vendors, but this swap apparently has "unbelievable" gains.

Basis Sport Tuning Edition Manifold!

Hopfully, these two mods will start squeezing some juice out of this sweet little car!

[James]

Doesn't spoon have a TB out as well? What are those specs?