While building the next generation turbo motor for the 914, thoughts turn to putting the power down. I'm currently autocrossing with 205-50-15's on 7" wide Keizer rims, with a slight pull of the rear fender, the return lip cut off, and some spacers to keep things from rubbing on the inside. Puts about 8.3" on the ground for the 710's I'm running currently. I'm expecting around 200 whp, with a class min wt for the car of 2150 or so. I don't see a need to convert to 5 lug, as I have some nice panasports for street driving that I like, and the bigger brakes wouldn't buy me that much in a 60 second autocross. On a road course, yup, bigger brakes better, for autocross, lets keep it light. Car runs in what used to be SM2, is now SSM. Here's the kicker- even with 4 season old 205's, in 150+ car grids, with several national jacket winners and a dozen or so trophy winners, I can put the car in the top 20, top 10 if I have a great day. So how much more tire do I really need to have fun locally, which is what the intent of the car is. I know it will never be the perfect weapon for a season of divisional/national events in SSM.

Here are some options I'm considering:

- run 225-50-15's on the same 7" rims, do a little metal pounding/pulling to keep a basically stock looking fender profile. This would add about an inch of rubber on the road from the 205's, and be the cheepest solution, other than just staying with the 205's

- run 245-50-16's, which would require new rims in a 16 x 8 size, 4x130 bolt pattern. Diamond racing makes a 20# rim for $150 that would work, (but is a little porky) has a 4 1/2 back space, should fit under a standard GT flare, but this means more $$$, rims, FG flares, install, in addition to paint. It only adds about 1.5" from the 205 size contact patch, only 1/2" from the 225's. I don't expect I could get all that much for my Keizers, and new ones would be what, 1200 to 1500 or so? Thats alot of green.

- run the hoosier 275-35-15's, which like a 9.5" rim. I could get new hoops for the keizers, and keep the inside hoop and hub, which would keep the correct back space and bolt pattern for the car, would still need flares and paint. This tire puts 10.8" on the ground, approx. 2.5" up from the current 205's. Haven't checked lately, but don't think I can tub the car in SSM, although in XP that would be allowed.

Anyone running the 275-35-15 on a 914, or anything similar in a tire/rim/flare combo? Can it be done w/out making the car stupid wide, which of course would not be the best for slithering thru a slalom? Up north here in WI, the guys running slicks have problems for 1/2 the season- it just is so hard to get even the softest of them up to temp unless we have hot sun and 90 degrees out, so I would plan to stick with the DOT "R" rubber.

Thoughts?

You will do much better autoxing with 15" wheels.

How much torque in the motor?

I have been running 225's on 8" rims under stock front fenders and pulled rears (no cutting). Great fit. Fills the wheel wells nicely from an aesthetic standpoint. You won't gain as much as you hope by just stuffing 225's onto the 7" wheels. If you're really looking for cone-dodging performance, you need to get whatever tire you're using onto as wide a wheel as you can.



A problem with 245/50-16's is that your gearing will suffer pretty badly. And on tighter courses you may actually find yourself needing to reach for 1st. With that motor, I'd be nervous for the 901 gearbox. And, with that much sticky rubber, you need to start thinking about chassis reinforcement.



If you're really wanting to build the car into a beast for autox, that's what I'd recommend. If low power DSP and FSP cars are already going that route, it can only be a good thing. 9.5" rim is too narrow to get the most out of those tires. At least 10" if not 11". On a 9.5" rim, you're basically pinching the tire to fit (the minimum rim width for that tire is 9"), and loosing a lot of your contact patch and responsiveness in doing so. You can't tub the car, but you can cage it, and that will help considerably. Again, with big sticky meats, you really gotta look at chassis reinforcement.

Watch FSP this year at Nationals for the Mannix/Wenzel mobile. They've built a beast of a BMW 2002. Less power by far compared to yours, similar weight, and running the 275's on 11" wheels.

Me, I'd LOVE to graft big flares to my car and run the 275's. But it's not in my financial reality...

-Josh2

...4... four seasons>>> is that four years?....age and heat will "harden up the compound". a lot...get a new set of tires, and do some shorter gearing.,which just may get you into the top ten ,or class winner faster..keep the 15" wheels. :

Some follow up- yes, 4 "seasons" = 4 yrs. I know I'm WAY overdue for new skins, but the old ones still seem to have a little life in them, and more time/money has been directed to the turbo project. I suspect that even with newer 205's the car would be much faster, even though I properly store the tires each winter.

Some tire and wheel info:

205.50.15, 22.9 diameter, 5.5-7.5 rim width
225-50-15, 23.8 diameter, 7-8.5 rim width
245-45-16, 24.6 diameter, 7.5-9 rim width
275-35-15, 23.0 diameter, 9-11 rim width

I'm expecting around 200/200 for whp and wtq, we'll see what I get. I'm going with a moderate amount of boost, keeping some compression and timing, and a smaller turbo with a big intercooler to make this a fat TQ motor, not a 9000rpm honda ricer turbo, with 25 psi boost and 7.5:1 cr, and no power below 6000 rpm. I'm shooting to give my friend and his elise a run for the money, and his car is around 2000lbs and 190 chp.

Wheel size- yes, width DOES matter that much. I had some 205's initially on factory Fuchs rims, pinch city. Just moving them onto the 7" Keizers really woke the tires up, so I can see what Josh2 is saying about going to an 8" rim for the 225's. On the 7" rims, the 205's look like steamrollers, and they're only 205's.

As my wife does like a ride in the car from time to time, a world beating autocross car in not in the cards for me, until the next wife comes along. Not a likely event. So. No gutting the car, no cage, it will remain a 75% car. Nancy has 3 rules for car prep, shorter than the scca bible, but just as restrictive: Has to look like a 914 when I'm done. Has to run on pump gas we can get anywhere. Can't morph into something that needs a truck and trailer to get to and from events.

Josh2, what rims are you running? I like the idea of keeping the car looking "mostly" stock, not incurring the expense of flares, install, paint, keeping the car narrow, and maybe just re-building my Keizers to 8" and rolling with the 225's. Add or link up a bunch of pics of the wheel openings. So you didn't need to modify the front at all for the 225/8" combo? I'd love more pics, close ups if possible, of the front and back of your set up, as this is the direction I'm leaning. If you have any pics of the pulling party to mangle out your fenders to fit, that'd be cool to see too. If its to much to add or link to, PM me and I'll send you an email addy to send the pics to.

While those 275's would be tempting, I'm not sure the added width would be worth it for a 75% car, with no cage or additional bracing. Now for that magical 100% car we'd all build if/when our ship comes in, well...

(I suspect that when my ship does come in, my dock will be rotted away, and it'll have to pass me by and end up at some other guys place.)

Doesn't matter that you store them properly (well, okay. It matter a -little-). What -does- matter is the number of heat cycles those tires have gone through. Most 914 autoxers will turn DOT R tires to rocks long before cord is showing. With 4 seasons of regular autoxing on those tires, they're now rocks. Little doubt.



Two sets of rims right now. Keizer and Diamond. Both 15x8 with just under 5" backspacing.



Fronts were untouched. The rears I used the "fenderizer", a rounded hardwood 2x4. Considerably more aggressive than the baseball bat technique, but it got me around 1-1/2". Paint cracked and little, and the metal's not perfectly smooth, but it got the job done. More time and effort, could have done it alot nicer.



Here's what I've got right now. I can try and get you some more in a couple days.

Click to view attachment
Click to view attachment

It's a tight fit to be sure. Fronts rub only at full lock.

-Josh2

8s (with 5 inch backspace) work up front, 10s don't. 9s, with all the backspace that will fit, might work. I'd try 8 X 15 with 225s up front, 9-10 X 15 with 275s in back. You'll need the 275s if you get the torque/hp you expect.

The 275/35 X 15 are 23 inches tall.
Look here for info:

https://www.hoosiertire.com/rrtire.htm

click on "specs".

One thing to consider is how hot it gets where you AX. I've seen times when some of our big AX 914s just don't get the heat the tires need in our feb- march and november AXes. Going to a 275 for our light little cars makes it really hard to get heat in them. I had 225 50 r15 V710s on my car and I now have Hoosiers 225 45 r 15s on there. I can aready tell a BIG difference with the gearing and the stick. I have only had one event on them so far but I'l let you know more after this weekend .

With the power you're talking about I would think a 225 to 245 would be perfect in the rear. 225s in the front is all you really need on a stockish type body. Just try to get the lowest profile tire you can..... 40 or 45 if you can find it for a 15" rim is perfect.

JP: don't know how I missed the 23" on the 275's, I corrected the prior post.


Josh2-

Agreed that my current tires, no matter how carefully cared for, are now rocks.

Keizer and Diamond. Drys and wets? Which to you prefer, and why? I was surfing the Diamond site, they look to have a 15 x 8 rim for $110 or so, coming in at 16 lbs. I always thought the Diamond/Circle racing steel wheels were tanks, but for anything less than a million dollars per wheel for a 4bolt pattern rim, that doesn't sound half bad. I'll need to look into the cost of updating my Keizers to 8" also.

"Fenderizer". OK then, that looks like one solution. Did the gaps at the door or trunk suffer when the fender was moved? I tried something similar, but less aggressive on my fenders, some pvc pipe, and jacking the air pressure way up in the tires, it was a kinder, gentler pull, but not enough to fit 8" rims. Going to be in Rice Lake, WI anytime soon? Bring the big tool, I'll go out for the beer and pizza, you have at the fenders while I'm gone and I won't have to watch then...

Pics- thanks, and of course, more would be welcome. Close ups if you can. How much is your car lowered? Hard to tell in the pics you added, but the back looks a little higher relative to the front. Could be your preferred set up, braking and wt. transfer, or does the back need to be set like that to clear the tires?


Phoenix: I'm thinking 225 all around, easier to rotate tires, 4 matching rims, all that stuff. Sure, if the motor comes together and makes crazy power, I might be wanting for more tire in the back, but we all need to keep in mind, this is intended to be a still streetable weekend toy for me to tinker on and toss money at, not a full tilt rule the world autocrosser, so if I have a little more HP than handling, I can dial the boost back a little, exercise rt foot restraint, or figure out how to fit the 275's on at that time. Our early and late season events can see 50 degree high temps, so I certainly don't want to go TO big on a tire for a local event car. Agree w/you on that for sure.

Like the sound of that 225.45 tire. Its about the same size as my current 205.50's. I recall way back when the AVS intermediate was the tire to have, I got some 195.50's, down from the 205.50's I had been running. Even that small change made a big difference in how the car would jump out of corners. Made for some pretty high revs on the highway at 80 mph, but was hard off the line and out of the corners. When I had burned those up, and went back to 205.50's, I thought the car was broke, it seemed so much slower off the line. I checked and bled the brakes several times thinking one was dragging...


More thoughts: If the 225.45's on 8" rims are a tight fit, how about this for a plan. Order up some Diamond rims in a 15 x 8, 4 1/2 back space, sell the keizers, add some flares, and a few spacers to widen the tires to fit the max width available by the flares. This does concern me as I don't want to fatten the car up to much and take away some of the slalom-abilty it now enjoys. And the flares would cost a little more for materials and labor than the "fenderizer"...

Again I'm assumimg you're gonna have the power you want. There is a reason for the fat rear tiar recommendation....the traction circle. All your front tires have to do is turn and can use all their grip to do so....more on this in a bit.
Your rears have to turn & and push the car forward, thus less grip is available to turn. The more motor you have the more critical this becomes......big sideways looks cool but it's not the quick way around. The grip of the fat tires allow you to get on the gas sooner.

Up front, you need to watch out for excessive scrub radius. I wasted a whole season trying to get rid of a tight turn push using 10 inch wheels. The steering effort was also very high. All my efforts to cure this made the car oversteer like a bitch on the fast stuff.
I finally figured out the scrub radius deal. Went to an 8 inch wheel (which reduced the scrub by 1 inch) and we were in business. The front tires are only slightly smaller. Spacers up front will also increase the scrub. As you said, getting heat in the fronts is a problem on cold days. Getting heat in the rears is less so...if you have the grunt.....push rears its head again.

I run 9" GoodYear slicks on 7" rims (see my avatar). The R250 is a very soft compound which works well for AX.

You'd have to do some creative pulling on those fenders to make them work, but at least you wouldn't need new wheels ...
Andy

Got the diamonds first, to make sure of fitment. Ran them with the 225's for a few years. Got the Keizers 'cause they're LIGHT. Stupid light. <10 lbs each. Unsprung rotational mass, that's the kicker. FOr autox, weight is everything.

I was lucky though, I bought 'em used from a fellow world member. I if were to buy new, I think I'd go with Spin Werks. They had the best product at the best price when I was looking a few years ago.

The Keizers are for autox only. They're very light, but they're also very soft. I will only trust ONE tire guy in town to work on them. And one "oops" at the track, and I could easily prang one of the rim shells.

Diamonds for the track (for now), Keizers for the cones, and Fuchs for the wets.



Diamond makes a great wheel, but they're not super light. The price however is hard to refuse.



There were a few "popping" noises when I was doing it, and I may have stressed the bottom corner at the door when I did it. I think it was impatience more than anything else. If I had taken more time, I think I could have been easier on the steel....



Not anytime in the foreseeable future. Here's what I did...

1) I got a hardwood 2x4, and bullnosed it with a hasp.
2) Put an old 225/50-15 DOT R tire on the wheel.
3) Jacked the corner up.
4) set the spring perch (I have adjustable perches, I think that helps) really high.
5) Placed the 2x4 (bullnose in and rounded part facing up) on top of the tire.
6) Slowly lowered the car down 'till the jack was clear.
7) Slowly pull end of 2x4 down 'till it made contact with the wheel.
8) Jack the car up again, relocate the 2x4 along the fender, repeat.
9) Keep doing this in different places along the fender 'till it's really easy at all places, then lower the spring perch a little and repeat it all again. Keep going 'till you can get the spring perch really low...

It didn't take me more than a few hours, but I'd recommend doing it in the afternoon of a hot sunny day, so the paint is as flexible as you can get it. The hotter the paint, the better.



I'll see if I can get some more pics. I run a light rake, but coincidentally, both of those pics are when I was trailing into a turn. So the weight transfer was forward.




Not enough backspace. You need 5" (or as close as you can get) backspace. My diamonds have 4-7/8" backspacing. They -just- fit.



Keep the Keizers and just get new outer rim halves.



If you get more stick under the car, you'll be able to consume slaloms like nobody's business. Stick is good, more is better. If you want to make the car a real a cone-carver, big ol' tahrs can't be bad...

-Josh2

The rears of a 914 will support 5 1/2" back space as will the fronts.

I run 22.5 x 9 x 15 Slicks and are nearly the same size as the 275.35 Ho's

DSP as I remember does not allow flares. at least not 914 GT style.

Stock fenders can not be stretched big enough to a 275

Turbo motor puts you SSM, flares and 275 Ho's are all good.

Like JP and Josh said More rubber the better.

Yup new rubber is the only way to go fast.

top 10 of 100 with your old tires tells me your pond is full but lacking any big fish. How do you fair with SSM PAX?

Oh and yes you can get heat in front 275's with a lite 914. It's called go faster. Gas is on the right, it goes to the floor.

Then there's the hammer dolly method....bout 5000 whacks per flare.
There is a 10 inch slick under there. I do a full range of suspension compression/lock check, no contact.

Really?? I have 4-7/8"backspace, and I'm right on the edge of rubbing the inner fender well on both sides. Just a reminder, all 914's are built a little differently...



Are you running standard GT flares? The big tahrs will fit?



Actually, SP has even more liberal wheel and fender allowances than Prepared. SP you just sawzall the clearance and let the tire hang out there in the wind. Prepared, you have to cover at least 1/2 of the tread face if I recall.



Yeah, fitting 275's require



S'TRUTH!!

-Josh2

Still researching and thinking... I have a friend on hard times and he had to mothball his Emod 914 autocross 914. It does have GT flares at all 4 corners. Another guy at our club runs the 275-15 Hoosier. Maybe I need to get one of his take offs this fall, and get it to friend #1, and just see how it fits in the wheel well. We may need to get it mounted to one of his rims, but could be an interesting experiment, as he runs hoosier slicks, not a DOT "R" tire.

Yes everyone- I know, I KNOW that I need fresh rubber, whatever size I decide it to be.

Joe, as for our little pond, here are the results from the recent CenDiv event in Milwaukee, WI.

http://www.scca-milwaukee.org/Solo/2009/E5/event5_fin.htm

Our guys were:

1 and 2 in: BS, BSL, STS, CSP, DSP, FMod
3rd in ST
1 and 4 in STX
2 in STU
2 and 3 in XP.

Not to be bragging, but yes, maybe a little- our driver education program has been growing the last couple years, and the results are starting to pay off for our members.

Back to tires... If the 275's will fit inside the GT flares... I called Keizer, and its $130/wheel to have the rims inspected and outside hoops changed to any size I choose... a 914 making 200/200 hp/tq running those skins could be interesting...

Looks like a good event, Dave, but where are the 914s?

Here is our last SCCA event.

http://scca.com/popup/raceresult.aspx?even...22&file=795


Btw, I have nearly 3/4 inch tire to inner fender clearance at the back.
I also have rub marks on the inner fender wall. At some point we neeed to keep the tire pressures up to forstall this problem. When you're really pushing the envelope tire deflection can become an issue. Note the rear tire.

Question,
If a 5 1/2" back space allows rear inner fender well clearance.
If the rear is tubed, how much more back space could be had before the control arm is an issue?

Using a 5 inch backspace on my car I have about an inch clearance to the trailing arm....but remember, tire deflection. Also think about cantilever slicks. Using my fronts on the back....same 5 inch backspace, 8 inch wheels , they would hit the inner fender and be within about 1/4 inch from the trailing arm. I run only -.5 deg camber to boot.