Motor is a JDM H22A
Stock Ignition
Stock Intake Mani
I/H/E
Piecing together a new fuel system with a Walbro 255, new fuel rail, new FPR, slightly upgraded RC injectors, trying to decide on a throttle body. It’s an N/A car and I have no immediate plans to turbo it. I’ve read some anecdotal evidence that an oversized TB can be detrimental to performance so I’m trying to avoid that but I’d like to upgrade a little. There’s an apparent vacuum issue with either my current TB or IAC and I’m in “screw it I’m replacing things” mode. We will be dyno tuning the car after install so the ability of the stock map to cope with the TB is not a concern. I am currently looking at a 68mm TB.
Question: Is there a real reason that a 68mm TB would be detrimental or in any way be the wrong choice?
Yes. An oversized throttle body can affect a few things.
If your IM is not port matched to the larger throttle body, then it is doing nothing. If you do match the IM port to the big TB, and the head/cam choice is suboptimal, you’ll do nothing but shift your powerband up to a possibly useless RPM range.
Unless your duty cycle values are way up, there is absolutely no reason to put in larger injectors without an intake tract sized accordingly to pull in air, and a head package that allows the use of more flow. Fuel rails are worthless in general, and a bigger fuel pump isn’t going to do anything. If your car is almost totally stock, you aren’t even close to maxing out the OEM delivery system.
Is there something your are building towards…that will necessitate the above modifications?
If you are going to TB it, then I’d be looking for a type-s IM to go with it. I know I didnt hook up the IAB when I put the motor in ( ), so might as well get a less-complicated piece in there.
I don’t have any illusions that my motor is overtaxing the capacity of the stock fuel system or the flow properties of the intake. I have intentions of PnP/building with Type S cams in the head and next year doing a low boost turbo, so the parts are serving two purposes for me, replacing a couple of parts that are currently suspected of intermittent failure while also making some provisions for future fuel/air demands.
68mm is the smallest aftermarket TB I’ve been able to find at a decent price, I’m just trying to confirm that it won’t be detrimental if I run it prior to the head upgrades. If the answer appears to be yes I’ll just get the stock TB cleaned up or rebuilt and look at a larger bore later.
It may be nominally deterimental, but if you are going to need it in the near future then go for it. Domination bores TB’s for a great price…so that is an option as well.
The TB I’ve been looking at is listed for the ITR (which is 62mm stock) but at least a couple people are running it and it’s supposed to bolt right on. I know Skunk2 TBs are cross listed for every Honda engine family (B/D/F/H) so it seems any Honda TB should bolt up.
I just foudn a 65mm TB that seems like it would be a good compromise between stock and the more common 68mm stuff. I have heard good things about some “Maxbore” guy in Florida as well, though the price is not much less than a new TB. I will have to look into Domination’s bore service. Have you used them, Steve? I assume they cut a new butterfly and everything?
I have read (on the always reliable internet) that H22’s are very “picky” about intake manifold changes. There are dyno charts showing that the Skunk2 IM actually makes less power on a stock head. Supposedly Skunk2 recommended over the phone that the IM only be used for raised comp/turbo/engines with head work. Still looking for a direct comparison with the Type S intake.
T-minus 2 months before I buy an H22 block from JTech and start building something stupid.
I have personally seen some of Dominations (Jay) work and it is very nice (say it like Borat).
I haven’t used them personally, but I have used OEM re-bored units in the past from Maxbore. Either way it worked…Domination is closer and cheaper.
I have heard stories about H22’s touchy intake nature before, but I have a hard time swallowing it…not sure what to say about that since I don’t own/drive an H.
I would not mess with it right now. Leave it as is, and upgrade later when you have the mod support for it. You still have plenty of room to make power before that becomes a restriction.
), so might as well get a less-complicated piece in there.
coulda woulda shoulda