I searched the forum for Maxbore and found some info here. Then I googled for reviews. No huge gains, I did it anyway and now my bored, shaved throttle body is in the mail to me. Lets see if it's a waste or worth the bother. George of Maxbore doesn't like to work on our Euro throttle body's because they take more time than domestics. Perhaps I caught him on a slow week because he was willing. No scientific testing is planned. No before and after dyno. No 1/4 mile before and after either. Just the butt dyno sensitivity gauge. When it gets here I'll post my impressions.

Les

 

I will be interested in your impression. It's difficult to find anything that will give us any measurable gains, mostly because the engine is so well engineered. In the history of the automobile there is no magic formula on engine design, just chance, like the early Ferraris and their Colombo designed engines, or the Offenhausers at Indy. I truly feel ours falls into that category, very efficient, with a high output for so few ci's along with excellent reliability.

 

Still not in my hands. George had it bored and shipped in 2 days BUT it arrived at the local post office on Saturday and the Presidents said I have to wait. I'll get it on asap. Perhaps tomorrow afternoon.

Les

 

No hurry, my driveway looks like twin bobsled runs, I don't even have to steer. Some times the butt dyno is the best, I trust it myself and you being a racer, it's probably finely tuned.

 

Mail just arrived. I'm not overly impressed. The stock is 74mm inlet and bored out is now 75mm inlet. The stock outlet is 68mm and the bored one is 70mm and flairs out to 71. I had the shaft shaved but it still appears to be rather thick. Oh well, lets see when its mounted on the inlet.

Les

 

bored, or polished....lol.... Good luck Les.... doubt you see a gain, but you can see your smile while installing....

 

Crusty oledoc! I went through all the arguments pro and con before giving in to curiosity. Which in all reality is why I decided to try. I mean, if curiosity was enough to buy long tubes and install them ($3000) then what's this piddly sum? Follow me for a second. If a dual NW intake is good for beaucoup horses because of less restriction, then why not the throttle body? I've got more bolt ons than most so if it's going to benefit someone, it should be me.
It's so nice in my fantasy world ….. If I feel a big difference after the instal I just may, I say, just may put the stocker on, do a dyno, put the bored on, do a dyno and report to the masses. As a curiosity, of course.

Les

 

I see you peaking in Import! It's your TB that got the treatment.

Les

 

you'll probably notice an improvement in throttle response

 

I feel like confirmation bias is going to make you feel like there's a slight improvement whether there is or not....

 

Les, thanks for doing this experiment!

 

LMAO.... anything that improves air flow is an improvement.... even so slight... Not going to be a big improvement, but an improvement. We use to polish everything in the old days... Too old now... Just do the big gains now...

 

Ok, yes, I am curious, blue version. LOL Our cars are sensual!

 

when it gets warm and my new garage is ready I will still be trying to debug my dual throttle body design, it works just had issues in normal driving conditions, Enjoy. Woody

 

Very Cool! Could you expand on your statement that "it works"? Sounds exciting.

 

so If i take my TB to a machine shop and say bore it "polish it" to these specs.... I can have one like yours?

I'd love to see a new aftermarket TB for cheap that worked for our set ups.

 

No you can't. A new larger butterfly has to be fabricated and the shaft that the butterfly fits into must be elongated.

I put the throttle body on and went for a drive. First impressions on start up and pulling out of the driveway were, nice ….. smoother …. better than before. On the way back from the grocery store I wound it out in 2nd. Hum, it seemed to miss a bit for a moment and then the check engine light came on. Hum. Well, it's a P0505, idle speed control, strange since it idles perfectly. I cleared the code and will do a throttle reset before going out again.

Les

 

I suspect you may have gotten a lean miss - my dual throttle bodies will do this when engine is cool. May be too much air and mixture is off - lean. Woody

 

Today I did a throttle reset and went for another drive. No codes! The AFR's are leaner but still in a safe range. No difference on todays butt dyno. Who knows, tomorrows or the next days may show huge gains.

Les

 

I suspect that this modification would show a performance gain on a N/A car, not so much on the SC ones. I hope that you see enough to have been worth the expense, maybe on the track.