DP 914- What does it take?, Spinning this off from Nat Thread.. Options

[7275914911]

The 2011 Nat thread talk about getting competitive in DP is not the first time I have had thoughts on this. After bringing a "Knife to a Gun Fight" the only 2 times I have competed on the Nat Level (SSM and FP) in my 2056. I am only going to help someone else win tires in that company.

I will be back in Oct in Blythville tho because its in my local region and it's a blast even when you are bringing up the rear!!

Enough rambling back to the topic...
What would a competitive 914 have to look like from top to bottom. What can/can't be done and what can/can't be replaced?

Thoughts/ideas/input are always welcome.....

[J P Stein]

What would it take? MONEY!

There isn't enogh room here to answer your question, but the answer lies here:

http://www.scca.org/documents/2011%20Tech/...olo%20Rules.pdf

Pg. 199 is not a bad place to start reading. All the pages relative to your quest are spread all over hell & gone within the rules. You'd best become familiar with THE BOOK..

As a side note, the fastest time for DP at the Packwood NT was about 2.5 sec under the fastest XP time......one of them pesky Miatas, very well driven & under better better conditions......but NOT 2.5 sec better. His time was 1 sec + better than the CP national champ in his monster 600-700 hp Mustang running in the same group.

[7275914911]

I was afraid that MONEY would be the simple answer...

And I know I will need a lawyer to really figure out that BOOK out??

But read I will...

[PeeGreen 914]

I am building for GP which may make more sense for a 914. DP is a bit more expensive. (IMG:style_emoticons/default/beerchug.gif) GP starts on page 212.

[J P Stein]

Yes, reading the book is a challenge but doable....even I can. (IMG:style_emoticons/default/blink.gif)

The good news is that you would not have to spend a bunch of money on light weight body parts.
If your motor is 2000 ccs the weight figures as follows:

2000 X .95 + 250 = 2150lbs

You can spend all your money on suspension, chassis stiffening, wheels & tires, engine & trans.....more than enuff to put you in the poor house. (IMG:style_emoticons/default/biggrin.gif)

Then there are those pesky Miatas......the 4th place time in DP would have won XP at that NT......which J. Daniels pointed out to me with a grin.

2011 Packwood National Tour
July 16-17, 2011

**** UNOFFICIAL RESULTS (INFORMATIONAL ONLY) ****

Class standings for DP [5 Cars] (7/17/2011 2:48:01 PM)

---------------------------------------------------------
T 1 194 Ron Bauer 2011 Mazda MX-5 Green/G Hoosier
47.883 47.720 47.076 92.924
47.151 46.340 45.848
---------------------------------------------------------
T 2 96 Keith Brown 1990 Mazda Miata orange Avon
48.843 48.565 47.929 94.977
47.048 47.341 48.538(1) (2.053)
---------------------------------------------------------
3 94 Karl Coleman 2011 Mazda MX-5 Green/G Hoosier
54.863(3) 48.235 48.349 95.502
49.432 47.395 47.267 (0.525)
---------------------------------------------------------
4 90 Jim Daniels 1994 Mazda Miata Red Hoosier
48.781 48.884 48.779 96.054
49.670(1) 47.825 47.275 (0.552)
---------------------------------------------------------
5 41 Derek Loree 1990 Mazda Miata red Hoosier
53.047 54.630(1) 52.159 102.946
52.206 51.356 50.787 (6.892)


I didn't get a chance to talk to Mr. Bauer but I think his engine is 2000 ccs and modified. The 2nd place car has 1600 ccs, (1760lbs minimum) but less tiar. It ain't about HP but handling.

[7275914911]

Jon, I had glanced at GP but did not see the 914 listed on the car list?

My car is 1900 lbs so I would have to gain weight in DP. Wanted to keep motor, maybe Ham heads would be only new expense there. Would 5 lug conversion kill me in either GP/DP?

Suspension/stiffning looks like biggest cost with the car I have to work with.

[jhadler]

Suspension, suspension, suspension.

The 914, as great a car as it is, has an inherent disadvantage when building for a class like DP.

The first is the formula for displacement vs. weight. The same 2000cc displacement is VERY different between a miata and a 914. The former being a high compression, multi-valve, DOHC motor. The later being an air-cooled, two valve, pushrod motor. Not that a 2.0L TypeIV motor can't be made to be a screamer, but it will take considerable investment to develop a TypeIV motor to get to the same level that a warmed over miata motor can deliver.

However, power is not what wins. And the miata has a VERY good suspension design. A lot of work, and a lot of money will be needed to engineer a suspension for a 914 to even that playing field.

And then there's weight. That gets back to the motor thing... Weight is critical, and having to haul around extra weight is gonna be a killer.

I love the idea of a competitive DP 914, but the reality is that it'll take someone with a ton of money, and a fiercely stubborn attitude to get it done.

-Josh

[J P Stein]

5 lugs are a bonus if you have them already. Lots of wheels are available. I've found that you're pretty much limited to an 8 inch wide wheel (std 911 offset) in front.

Well put, Josh.
Let's face it, the guys at the pointy end of the classes are hardcore.
The 2nd place DP guy at tht NT *will* (IMO) show up with bigger tires at the Nats.
He was experimenting with 13 inch Avons IIRC. Bauer was experimenting with 16 inch R75 Hoosier radials. Such is life at the pointy end.

[PeeGreen 914]

Scroll down further in the GP section and you will see the 914. The engine size is limited to 1795 and weight min is 1795. Wheel size is 7" max. However, you must use the original calipers so the 5-lug conversion may not help.

[7275914911]

Maybe I did see that on the GP cars...Also limits to 32 carb size IIRC.

Lot's of good info coming out here. My car might not be the right car to build out to DP. But I know a guy that has a roller(@scottyB's), stroker 2270 t4(just needs assembly) and a tranny(evil just needs to know what gears) just waiting to be put together. Not sure about suspension but it is a 5 lug conversion that is getting flares.

It looked like 7" wheels w/o penalty. 8's slight weight penalty up to 10's. As Josh states weight looks like a killer...

[PeeGreen 914]

Maybe I did see that on the GP cars...Also limits to 32 carb size IIRC.

Lot's of good info coming out here. My car might not be the right car to build out to DP. But I know a guy that has a roller(@scottyB's), stroker 2270 t4(just needs assembly) and a tranny(evil just needs to know what gears) just waiting to be put together. Not sure about suspension but it is a 5 lug conversion that is getting flares getting flares.

It looked like 7" wheels w/o penalty. 8's slight weight penalty up to 10's. As Josh states weight looks like a killer...

You should be able to fit a decent size tire on a 7 for the 914. Fordahl seems to think I can build a 150hp 1.8l (formula is his) for this class. He feels a 914 would tear up the competition in this class. I'm not sure how it will do but I have someone who is a VERY good driver and myself (not too shaby) to test this with next year. We shall see how it goes (IMG:style_emoticons/default/beerchug.gif) . It's really not too expensive to build this and if it doesn't go the way I am planning it will be ready for a big type IV (IMG:style_emoticons/default/beerchug.gif)

[7275914911]

On my car know i have been able to get 245/45 A6's on my 7x16 fuch in the rear after a little baseball bat massage. I would think on a flared car you could run this size on all corners.

I am actually AXing with 225/50 A6s all the way around this summer. Had to stretch the front just so slightly. I ran take off 205/45 A6s last summer. Bigger(wider) is better I've heard....i was also told by a local Nats trophy winner that he never liked anything taller than a 45 aspect because of rollover. I went with the 225/50's mainly because I could rotate all four tires...theoretically last longer maybe? CSOB i guess...I believe I have felt rollover once this season and that was a small, tight local setup.

[PeeGreen 914]

For the GP car I would think a 225 45 r15 would be a good start. The smaller the radius the better since you have to deal with low power. I dunno, that is where I am going to start and work from there.

[Britain Smith]

Just use the cantilever Hoosier slick that I am using the in front. It is built for a 7" rim and has a thread width of 9.2"

-Britain

[7275914911]

@Brit...the 225/50 A6 has 10.2" and the 245/45 has like 10.4" tread (both are recommended for 7.5-9.5 rims). The 205/45's are around 9.2"(6-8" rec. rim). Those can be run under narrow body without any issues on 16's.

@Jon...i thought about 15's but I am looking for all the gear I can get with 16's. I'm even revving to 6200 now and thinking of going 200 more to see if it starts to float. I figure it is thru making power just hate to shift if i don't have too

[jhadler]

A 245 tire on a 7" rim is a waste of an expensive tire. It's not the number on the sidewall that matters, it's the contact patch it makes on the ground that matters.

A 245/50 tire that's shoehorned onto a 7" rim will pinch the sidewalls considerably. Sure, the tire can fit, but much of the tire will actually NOT be contacting the ground. At the next autox you're at, take a look at the stock class cars that cram as much tire possible onto their stock rims. See how the sidewalls bulge? When the sidewalls bulge, the contact patch of the tire lifts off the road surface. On a stock category car, where alignment, suspension, and sway control are limited, the only option left is to regain contact patch lost because of body roll. So that's done by cramming over-sized tires onto stock width rims. But that is an inelegant solution that is much better taken care of once you're allowed to muck about with the suspension and alignment of the car.

For a Prepared category car on radials (where your rim width is limited), you will want the opposite. You want the sidewalls of a radial tire to be as square you reasonably can. Now, in a category such as street prepared, where rim width is unrestricted, you would want to S-T-R-E-T-C-H the tire onto as wide a rim as you can. 275's onto 11" rims are not uncommon.

I second Brit's suggestion of running cantilever tires if you're stuck with 7" rims. ** the cantilever tires were made specifically for cars that have restricted rim widths.

As for your contact patch numbers? I'm not sure where you got them, but a 245/45-16 tire on 8" rims will give you a 9.2" contact patch, not 10.4". That's the contact patch of a 275 tire on a 9" rim. The narrower the rim, the smaller the contact patch for the same tire.

FYI: I'm getting nearly the same contact patch with a 225/45-15 on an 8" rim as a 245/45-16 on the same rim width. 9.0" vs. 9.2" contact patch. As Jake Raby often says..."it's all in the combo". ** and it's lighter, and geared shorter than the 245.

-Josh2

[7275914911]

Not sure what I was looking at with those 10" figures. The 245/45(9.2" width per Hoosier) were take offs and where used when stretching fenders. They are 7.5" wide at rim. The 225/50(9") that I did buy new are perfect fit on 7's per Hoosier. That is what I am stuck with at least till they wear out...

I'm learning more and more tho. Like pinching and stretching effecting contact patch. Good stuff for a real newbie!

[PeeGreen 914]

I am planning on using the cantis but still not 100% sure as it will depend on what tire I want to campaign for contingicies (IMG:style_emoticons/default/smile.gif) .

[J P Stein]

Maybe I did see that on the GP cars...Also limits to 32 carb size IIRC.

Lot's of good info coming out here. My car might not be the right car to build out to DP. But I know a guy that has a roller(@scottyB's), stroker 2270 t4(just needs assembly) and a tranny(evil just needs to know what gears) just waiting to be put together. Not sure about suspension but it is a 5 lug conversion that is getting flares.

I do believe the class limit for 914 DP engines is a 2.0L + a .040 over bore.
You might wanna double check that.

[Randal]

Yes, reading the book is a challenge but doable....even I can. (IMG:style_emoticons/default/blink.gif)

The good news is that you would not have to spend a bunch of money on light weight body parts.
If your motor is 2000 ccs the weight figures as follows:

2000 X .95 + 250 = 2150lbs

You can spend all your money on suspension, chassis stiffening, wheels & tires, engine & trans.....more than enuff to put you in the poor house. (IMG:style_emoticons/default/biggrin.gif)

Then there are those pesky Miatas......the 4th place time in DP would have won XP at that NT......which J. Daniels pointed out to me with a grin.

2011 Packwood National Tour
July 16-17, 2011

**** UNOFFICIAL RESULTS (INFORMATIONAL ONLY) ****

Class standings for DP [5 Cars] (7/17/2011 2:48:01 PM)

---------------------------------------------------------
T 1 194 Ron Bauer 2011 Mazda MX-5 Green/G Hoosier
47.883 47.720 47.076 92.924
47.151 46.340 45.848
---------------------------------------------------------
T 2 96 Keith Brown 1990 Mazda Miata orange Avon
48.843 48.565 47.929 94.977
47.048 47.341 48.538(1) (2.053)
---------------------------------------------------------
3 94 Karl Coleman 2011 Mazda MX-5 Green/G Hoosier
54.863(3) 48.235 48.349 95.502
49.432 47.395 47.267 (0.525)
---------------------------------------------------------
4 90 Jim Daniels 1994 Mazda Miata Red Hoosier
48.781 48.884 48.779 96.054
49.670(1) 47.825 47.275 (0.552)
---------------------------------------------------------
5 41 Derek Loree 1990 Mazda Miata red Hoosier
53.047 54.630(1) 52.159 102.946
52.206 51.356 50.787 (6.892)


I didn't get a chance to talk to Mr. Bauer but I think his engine is 2000 ccs and modified. The 2nd place car has 1600 ccs, (1760lbs minimum) but less tiar. It ain't about HP but handling.

Is that right, 400cc cost you the difference between 1760# and 2150#? Wow.

Or maybe there is a penalty in there for mid engine?