lap times vs. weight - any way to estimate?

i am thinking of moving to gp from itb with my crx si and want to get an idea of how competitive i may be without going big bucks on the motor.

the obvious thing is the 100+ of lead in the car i had to add to go from ita to itb.

now don't laugh, but i may be able to save money by racing in the national class by racing at nearby tracks for both regional and national events without traveling 600 miles round trip to other tracks.

600 miles at 12 mpg is 50 gallons and at $2.50 per gallon is going to add up not to mention motels and food, etc.

oh and i tend to consume more barleypops when away too.

tia,

tom

I have an 86 CRX that I run in GP. At a regional prod race you might do ok. Here in the southeast at a regional I have finished third overall in the prod group. In nationals I finish in the top three in GP. If you just want to get more track time then go do it. You will not be a backmarker.

Blake Meredith

The Club Racing Board will soon approve a 100 lbs weight reduction for the 84-87 CRX Si in GP (as well as a compression bump to 11.0:1) , so that should help out even with a stock motor. :023:

You'll enjoy GP, and once you get on real racing slicks it's SOOO hard to go back to DOT tires. :eclipsee_steering:

MC

(former ITC racer now GP racer...and frequent tormentor of Blake and his CRX! :006: )

thanks for the feedback. it may be difficult to get more weight savings than just the lead and keep the car itb legal.

but for a track like mid-ohio, is 100# gone something like 0.2 seconds or 2 seconds?

that's part of what i want to try and figure out so that i can compare to other racers.

also, what would the slicks be worth on my car? 1 or 2 seconds at mid-ohio?

tia,

tom

p.s., thanks for not laughing regarding my plan to save money. i need to sell this to my wife with a straight face. i keep practicing with the mirro but have'nt done it yet.

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Originally posted by tom91ita@Dec 20 2005, 04:25 PM
thanks for the feedback. it may be difficult to get more weight savings than just the lead and keep the car itb legal.

but for a track like mid-ohio, is 100# gone something like 0.2 seconds or 2 seconds?

that's part of what i want to try and figure out so that i can compare to other racers.

also, what would the slicks be worth on my car? 1 or 2 seconds at mid-ohio?

tia,

tom

p.s., thanks for not laughing regarding my plan to save money. i need to sell this to my wife with a straight face. i keep practicing with the mirro but have'nt done it yet.

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Don't know if this will directly correlate, but when I converted my ITC Scirocco to GP I did the following:

* removed all bumpers, door glass, headlights, etc. Dropped about 180 lbs out of the car total. (Bumpers were 80 lbs alone!)

* put on slicks

* Went to a SMALLER engine (1457cc vs. 1588cc ITC engine) with an IT bottom end and an IT head w/ mild race cam. No porting was done. Probably made 5 hp
more than my ITC motor and less torque.

* installed a close ratio gearbox

Between the weight loss, slicks, and a better gearbox, I dropped FIVE seconds off my times at VIR, and FIVE seconds at Kershaw. That put me at the front of the regional pack, but mid pack nationally.

Hope this helps with your decision.

MC

thanks. just the type of info i was looking for with regards to lap time improvements even if it is with both tires and weight.

i may do the weight part first and use up the old tires before i go to the slicks.

tom

Quote:

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Originally posted by tom91ita@Dec 20 2005, 02:49 PM
thanks. just the type of info i was looking for with regards to lap time improvements even if it is with both tires and weight.

i may do the weight part first and use up the old tires before i go to the slicks.

tom

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Tom: The car already has a fuel cell, fire system, etc that are required in PROD?

I follow this type of thread carefully since I am planning on the day when I go either FP or EP.

no the car is not ready for prod. but to justify the cost of the fuel cell, etc., i could rationalize that i could race closer to home instead of longer tows and trade-off fuel bills for car development.

i still want to go to the fort wayne brat bash each year but other trips could be minimized. i am in michigan and could race at grattan and gingerman for both regionals and nationals.

it would end up being a mixed bag between being somewhat competitive in itb or not as competitive in g-prod.

part of what i want to know for losing the weight and gaining slicks is if each item is worth about 1-2 seconds per lap, i can look at laptimes for last year and get some idea of where i would be/ could be.

the stupid nasa deal at mid-ohio also has me thinking about honda challenge and running enough of their races to qualify for H5.

lots of options and no decisions! i need to study the prod rules closer too. don't want to spend money on anything in ita or h5 that does not advance g-prod or is not allowed in g-prod.

tom

Tom,

Have you posted your question on the Production Car Discussion Forum? There are people over there who have moved from IT to Prod. They can probably help you with this question and others that are sure to come up as you convert your car.

Good luck,
Perry
Former SM now F Prod Miata

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Originally posted by tom91ita@Dec 20 2005, 12:25 PM
but for a track like mid-ohio, is 100# gone something like 0.2 seconds or 2 seconds?

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Go download Bosch's amazing simulation software "LAPSIM" from their motorsport site.
http://www.bosch-motorsport.de/en/pu...ion/index.shtm

You can find a Mid-Ohio track file on the net somewhere if you look hard enough. I woudl also bet some of the Honda tech forums may have Honda car config data you can plug in. Perhaps some of the HART engineers can help you there?

Then you can find out more than you ever wanted to know about exactly what changes will do for your laptimes.