Hello all, I’m thinking about having my TB bored and was wondering if the butterfly plate would need to be bigger or if anything else needs to be modified?
I would assume the car would sit at a high idle and/or throw code and would like to try to prevent that if possible.

 

Yes, you would need a larger butterfly. I'm not aware of anyone boring these throttle bodies at this point.

 

Do you think a local Supercharger shop would be able to do it? I’m bringing my M112 to have it rebuilt and stage 2 ported to a shop near me that specializes mainly in supercharges but also performance mods.

They say they can bore the throttle body but said they would need it in-person to see if they could make the bigger butterfly.

 

There's other threads on here that talk about boring the TB, you'd find the max size you can get to there. I can't remember who said it, but I recall reading it. A search might find it, if you ask the right things.

 

Maxbore was only about 30 miles from me, first his machine broke and couldn't do them anymore, then he passed a few years back.

The initial bore was 78mm, then it went to 82mm and that was with a resleave I believe. If you just want to know results to get info after the work is done, do as Hooli said and do a Search....just put in maxbore.

 

I thought the guy from MB retired?

There is a place in cali that will port above and below the butterfly but not bore it out.

There is a thread within the last year of a forum member going all gung ho having his AJ26 TB bored as he has access to some machine shop. I hope he made it happen. I don’t believe he has followed up on his progress on here though. Perhaps a thread search, post an update on his progress (if any) or a PM would get him to post any updates in return. I don’t remember his screen name.

 

That gung ho guy is me. I completed the throttle body including the throttle plate but have not yet gotten the car back together. My original plan was to wait and make sure there were no issues before updating the thread etc. I will do so now though.

The throttle plate is not easy to make. It’s difficult to get a very precise measurement on what the angle is when it’s closed, so as a result it’s difficult to do the math on how much larger it needs to be to properly correspond to whatever your bore winds up being. In addition, the shaft needs to be modified as the slot the plate sits in needs to be made wider.

The stock plate leaves approximately .001” gap all the way around when closed. Mine is at around .002” This may result in an issue, but only testing will show for sure.

 

Cool! I’m glad to hear that the TB is back together at least. Not many people have access and/or willingness to take on such a project. I hope it turns out well for you. 😊

 

Sorry . I have been busy lately with my personal matters. I don't have much time to repeat. But I rebuilt my TB and SC the past 2 years with all possible upgradeupgrades.

You can search my threads. My TB is ported not bored. NoT by maxbore . So butterfly flap is original then rebuilt.

​​​SC i rebuilt basically with all the option boxes checked.

I can share all of the vendors information

 

Yea if you wouldn’t mind providing the company names that’d be great.
Im looking to rebuild and port my supercharger but shipping it to powerhouse is double what the cost of the service is.

 

Porting the throttle body without increasing the diameter of the throttle plate isn’t going to yield anything at all. You can do it, but could also just save a few bucks. Porting the SC is basically the same. A gen 5 unit is cheap on eBay and those are optimized from the factory. Just save your money.

 

I don't want to grill you on the forum as a newer member but theory and reality are 2 different things.

I have been with this forum longer than I could even remember. you are not all wrong porting is not as good and ideal as the full bored. but saying porting both TB and SC are not going to do anything and save a few bucks is a wild statement that I could not hold myself anymore to respond.

I did it ,tested it and experienced the power gain and exactly the difference it makes so I have the solid right to say what I can say from my primary source and first hand experience.

we should be humble some times....a lot of things I still need to learn here

 

I don't want to grill you on the forum as a newer member but theory and reality are 2 different things.

I have been with this forum longer than I could even remember. you are not all wrong porting is not as good and ideal as the full bored. but saying porting both TB and SC are not going to do anything and save a few bucks is a wild statement that I could not hold myself anymore to respond.

I did it ,tested it and experienced the power gain and exactly the difference it makes so I have the solid right to say what I can say from my primary source and first hand experience.

we should be humble some times....a lot of things I still need to learn here

 

Isn't it true that we all have various perspectives on what has worked for us...
or what has not worked. I find it a great big positive that we have such a
wealth of opinions that each of us can weigh for it's own merits.

 

Randy. I know you are a true gentleman and your words are too kind.

​​if that really isn't working based on the person experience let's say AFTER the Porting and near no power gain. It's a fact and preference we all respect. But just saying with a theory.. That's something different.

But some times the seasoned members need to teach the young bucks to behave.

 

No need to get emotional. I stand by the fact that modifying the throttle body without enlarging the butterfly is not worth the cost with a machine shop. Maybe like 5hp being generous. We’re talking somewhere in the 1% range from stock. I also didn’t say porting the SC was worthless, I said the gen 5 Eaton from a later Jag is optimized meaning you can swap to that for a lot less money and see the same gains. These cars are worth like 5k, why spend 2k to get like 20hp from what you’re describing? For most people it’s not worth it when you can get 98% of that for like 400 bucks. People can be sensible no matter how long they’ve been on a certain forum lol.

Anyways this conversation, like any of this nature, is totally pointless without dyno numbers.

I will admit that super cringe “behave” got me.

 

a habit doesn't need to make financial sense and I could have done a LS swap for more power per dollar if that is the case. but that is not the point of owning a Jaguar and more specifically a X308. yes. We DO spend 5 thousands dollars on a 3K worth car. don't those Honda EK fan boys do that also.

there is a lot cheaper and fast cars and expensive and fast cars. Jag is none of any of those. Before standing for your point, show us what you personally got on your Jaguar. Fact and data can be all found on the internet...we wont need to bother you stating the fact here. yes, we are those 2% you didnt mention kind of people and you don't sound like any of us. that is a disrespect you are paying to the fellow members, yes you do pay respect the seniority here and humble. we dont talk like this as Jaguar guys....

just like Porches...they are not fastest and cheapest...people love them also for a reason...

if you can read what you say again..everything is maybe 5hps....somewhere 1%.....worth 5K....spend 2K...like 98%....like 400 bucks.... where did you come up with those? all random make-up numbers...

we dont care about numbers here...welll...maybe the correct part numbers....