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-   -   Getting closer to getting the Porsche 928 SCCA classified as T1 (https://rennlist.com/forums/928-forum/1132316-getting-closer-to-getting-the-porsche-928-scca-classified-as-t1.html)

mark kibort 03-05-2019 09:47 PM

Getting closer to getting the Porsche 928 SCCA classified as T1
 
Ive been working on this during the off season and looks like we are making progress. soon, the Porsche 928 will be part of the SCCA Touring 1 class. I need the exact Throttle body diameter specification.. isn't it 88.9mm or something close to 3.5"?
thanks,
mark

mark kibort 03-06-2019 11:40 AM

Bueller?
anyone know???

rjtw 03-06-2019 12:40 PM

Good luck on this Mark!!! There are some measurements of an S4 throttle body here: http://www.928sg.com/intake.htm

Rick Carter 03-06-2019 02:10 PM


Originally Posted by rjtw (Post 15684373)
Good luck on this Mark!!! There are some measurements of an S4 throttle body here: http://www.928sg.com/intake.htm

Good info in that link.

Thanks Mark for continuing to carry the 928 racing banner, you're one of a very precious few.

928sg 03-06-2019 03:45 PM

74mm

http://www.928sg.com/intake.htm

mark kibort 03-06-2019 07:24 PM


Originally Posted by 928sg (Post 15684834)

ReALLY?????? 2.9"????? I have a hard time believing that! that's tiny... time to rip mine out.. maybe that's the bottle neck!! the euro is 3.3" (2valve) and I think the 85 S3 is something like 3.3 or 3.5. im guessing, but does anyone have confirmation?

mark kibort 03-06-2019 07:28 PM


Originally Posted by rjtw (Post 15684373)
Good luck on this Mark!!! There are some measurements of an S4 throttle body here: http://www.928sg.com/intake.htm

Thanks... wow... much smaller than I thought .. I might have given the SCCA guys some wrong info... I have to correct. I wonder if they mean at the plate or at the inlet of the throttle body? 80mm??

928sg 03-06-2019 07:30 PM


Originally Posted by mark kibort (Post 15685347)
ReALLY?????? 2.9"????? I have a hard time believing that! that's tiny... time to rip mine out.. maybe that's the bottle neck!! the euro is 3.3" (2valve) and I think the 85 S3 is something like 3.3 or 3.5. im guessing, but does anyone have confirmation?

I have pics and info on my site showing the big bore at 78mm but a typo on the page showing 79

mark kibort 03-07-2019 01:06 AM


Originally Posted by 928sg (Post 15685360)
I have pics and info on my site showing the big bore at 78mm but a typo on the page showing 79

so, its really 74mm and you bored it out 4mm as it showed on the pics (etched on the TB plate). interesting that the 85-86 has the bigger throttle body. we should probably list that as it is a stock component and you should be able to use different components interchangeably. anyone know what the 85 TB is in diameter? I'm thinking its at least the same as the euro 2 valve which is 3.3" at the throttle plate, which is 84mm.

mark kibort 03-07-2019 10:53 PM


Originally Posted by Rick Carter (Post 15684609)
Good info in that link.

Thanks Mark for continuing to carry the 928 racing banner, you're one of a very precious few.

Thanks Rick! My pleasure there is no reason the 928 cant join into the fun, right??????? :)

The goal was and always has been to find a class the 928 can compete in , on a national level and stage . I hope some take advantage of it!!!! T1 is a class where the 928 can flourish. im thinking a 928GTS bottom end, possibly the dual throttle body intake, and a hot cam. should be able to get in the 400 rwhp level while keeping the RPM in the 6600 rpm safe range.

mark kibort 03-07-2019 10:55 PM

IT'S ALMOST OFFICIAL
 
I just got word that the 928 will be part of the Touring 1 class eligible to run this season !!!!!!!

justaguy 03-07-2019 11:04 PM

Good work on getting the car classed, now that it it has a class the question is will it be competitive in the class? what other cars are in T1? I'll come down and run a race or two if there is a chance of having some one to race with.

mark kibort 03-08-2019 12:23 AM


Originally Posted by justaguy (Post 15688241)
Good work on getting the car classed, now that it it has a class the question is will it be competitive in the class? what other cars are in T1? I'll come down and run a race or two if there is a chance of having some one to race with.

Thanks! Yes, it will be competitive at the regional level for sure, but a little behind the curve with the allowance for the ex-GT world challenge cars they have allowed to run in the class. However, vs what I was having to run against, at least these are production based race cars rather than factory race cars , such as the GT3, or TransAm2.
T1 is pretty loaded and the cars you would run against are the newer Mustangs with the 440hp engines, caymanS Porsche 997, viper, corvette , NSX, camaro, and many others. the NSX was a little bit of a cheater car, but the cars in the bulk of the group were not too far off my times at Sonoma. I think I would stack up a little better at Laguna due to the track and the 928 characteristics. either way, a well driven 928 should be a top 3 car at any regional race, and top 10 at the national level. Ironically, the reason I got a top 10 finish , was due to the reliability of the 928... funny, right? ;)

justaguy 03-08-2019 10:58 AM

Car 51 currently makes 275 hp and 300 tq I could get it to 300/300 with some proper tuning but it's never going to make 400 hp which is what it would need to compete in T1.
Congratulations once again on the 10th place at nationals. That was great to watch

mark kibort 03-09-2019 03:55 PM


Originally Posted by justaguy (Post 15688939)
Car 51 currently makes 275 hp and 300 tq I could get it to 300/300 with some proper tuning but it's never going to make 400 hp which is what it would need to compete in T1.
Congratulations once again on the 10th place at nationals. That was great to watch

Thanks! yes, it was an exciting week at nationals. I'm just glad the car ran flawlessly the entire time and I had a chance to run REAL slicks on a tough track! they only have a day or so on them, so it will be interesting to see how they do at laguna later this month.

As far as the 928, yes, its pretty exciting to me that it is now nationally recognized and now anyone can run in this class. sure, you wont be able to run with the national front runners, but the idea of the class (fundamentally, but not actually) is to have production based cars with limited modifications. so you see Maseratis , Ferraris, corvettes, all with limited mods , DOTs and with your car, you will be right in the action with a lot of them at any local club SCCA event. AND, more importantly, you can go to any SCCA Majors event, (Super Tour events) which is pretty exciting as well. running a car below the T1 (Touring 1) spec is not uncommon. a few of the guys on the racing board have been doing this for years . I think we need to find you an S4 to pump up!


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