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The Myth of VPi adjustment for fuel capacity


mender
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I keep hearing about this idea that VPi has some sort of factor for fuel capacity. That is used as justification for saying that certain cars have a low VPi because of a small tank and that everything is fair and equitable as a result.

 

I've gone through the cars that I know well on the VPi list looking for differences in VPi due to fuel capacity and I can't find any. Anyone?

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The only thing I can come up with is a response I got from tech regarding the difference in values between s4 and s5 rx7.

 

(Im paraphrasing, not quoting) The reason for the difference in values is due to the larger fuel tank and 15 hp increase between the series.

 

So, how much is the 15 hp worth?  How  much is the 2 gallons worth?

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49 minutes ago, wvumtnbkr said:

The only thing I can come up with is a response I got from tech regarding the difference in values between s4 and s5 rx7.

 

(Im paraphrasing, not quoting) The reason for the difference in values is due to the larger fuel tank and 15 hp increase between the series.

 

So, how much is the 15 hp worth?  How  much is the 2 gallons worth?

Good question. So 75 points between S4 and S5. Probably easiest to take the hp out of the equation first and see what's left.

 

First gen had 100 points between the 100 hp 12A and the 135 hp 13B. What other differences were there?

Edited by mender
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5 minutes ago, mender said:

Good question. So 75 points between S4 and S5. Probably easiest to take the hp out of the equation first and see what's left.

 

First gen had 100 points between the 100 hp 12A and the 135 hp 13B. What other differences were there?

Different brakes, efi, lsd, bigger rear axles, etc....

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First gen 12A at 100, first gen 13B at 200, second gen S4 13B at 275, second gen S5 13B at 350.

 

First gen 12A to 13B had a different diff ratio and larger axles if I remember correctly, other differences are minor as brakes are within 2X.  13B first to second gen was a complete redesign and not comparable cars with a change to aluminum suspension components, independent suspension, heavier, etc.

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13 minutes ago, karman1970 said:

4th Gen V6 Camaro got a 100 point hit for what appears to be 1.3 gallons (though it's a year off).

One has to be careful to separate the AIV hold-overs in the VPi values of cars; '98 was a styling update so a different market value and I suspect the reason for the change.

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Not according to my sources for the 3800 transmission.  The 3.4 carried through at least 96 in some cases ( I believe in .CA, the 3800 would have been available late 95).

 

I would like to look into this more to see if I can open my search for more years for spare transmissions.

 

Edited after more research..  96 was the last year of the 3.4.

Edited by wvumtnbkr
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3 hours ago, wvumtnbkr said:

Not according to my sources for the 3800 transmission.  The 3.4 carried through at least 96 in some cases ( I believe in .CA, the 3800 would have been available late 95).

 

I would like to look into this more to see if I can open my search for more years for spare transmissions.

 

Edited after more research..  96 was the last year of the 3.4.

 

Is the T5 any different behind a 3400 vs a 3800?

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6 hours ago, karman1970 said:

 

Is the T5 any different behind a 3400 vs a 3800?

Yep.  Starter pocket position as well as trans bell housing pattern change as well as clutch fork versus hydraulic throw out bearing.

 

Also, to be clear a 3400 is not the engine in the camaro.  The camaro engine is the 3.4.

 

All 3400 were fwd and never had any manual transmission.

Edited by wvumtnbkr
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On 4/1/2018 at 2:36 PM, wvumtnbkr said:

The only thing I can come up with is a response I got from tech regarding the difference in values between s4 and s5 rx7.

 

(Im paraphrasing, not quoting) The reason for the difference in values is due to the larger fuel tank and 15 hp increase between the series.

 

So, how much is the 15 hp worth?  How  much is the 2 gallons worth?

depends on what you are starting with.. starting with a 80HP Miata engine 15hp sounds great, already have 300 or so...ehhh. 2 gallons for us would be nice but probably only worth another 10 minutes (track depending) 

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VPi list for 944 shows a 25 point increase from '85 to '86 and again from '87 to '88. Tank size is 21.1 gallons for '86 and later, up from 17.4 for earlier ones re: internet.

 

Changes:

'85 to '86: 4 hp and 3.7 gallons (among other things) for 25 points

'87 to '88: 40 hp for 25 points

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3 hours ago, mender said:

VPi list for 944 shows a 25 point increase from '85 to '86 and again from '87 to '88. Tank size is 21.1 gallons for '86 and later, up from 17.4 for earlier ones re: internet.

 

Changes:

'85 to '86: 4 hp and 3.7 gallons (among other things) for 25 points

'87 to '88: 40 hp for 25 points

Wrong. There are 3 cars to consider for the 85-86 years.  

1985- small tank, narrow wheel track, steel front control arms, 147HP

1985.5- big tank, narrow wheel track, steel front control arms, 147hp

1986- big tank, narrow wheel track, aluminum front control arms, 147hp

1987-big tank, wide wheel track, stronger wheel bearings/spindle, aluminum front control arms, 147hp

1988-big tank, wide wheel track, stronger wheel bearings/spindle,aluminum front control arms, 157hp, short 5th gear

1989-2.7L engine, big tank, wide wheel track, stronger wheel bearings/spindle, aluminum front control arms, 163hp, short 5th gear

 

all of the above is for 944 base only.

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3 minutes ago, TiredBirds said:

Shouldn't "VPI be based on the ACTUAL value of the car? Such as a POS clapped out E39 can be had for $300, but a nice 540 5 speed in  great shape can cost $3000+ Just saying....... and which is cheaper in the long run? (hint not the $300 car). 

AIVSUX.

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Just now, TiredBirds said:

what be AIVSUX?

Average Internet Value = AIV, a system whereby cars were given a market value that had little to no relationship to reality. The E36 appeared during that era even though only one region of the required four had rusted out E36s that could be bought for below scrap value.

 

AIVSUX was dogtired's standard line.

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3 hours ago, TiredBirds said:

don't get me wrong I like Chump/Champ but they way they figure "price" is a tad crazy. it has zero to do with actual build costs. Same with "points" for add ons.. JMHO

"Price" is long gone. Supposedly all about performance potential now. Except for the 2x stuff and any other hold overs from the AIV days.

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8 hours ago, karman1970 said:

"Price" is long gone. Supposedly all about performance potential now. Except for the 2x stuff and any other hold overs from the AIV days.

 

Price is in the formula for determining VPi.

 

"Vehicle Performance Index

All competing vehicles will be assigned a Vehicle Performance Index (VPi) by ChampCar. The Vehicle Performance Index is a POINT value that is developed and based on the General Market Value of your car... PLUS... a Performance Evaluation of your car. While some vehicles may have a very low General Market Value, they have a very high Performance Value. Similarly, some vehicles may have a very high General Market Value, but they are considered gutless-wonders. ChampCar maintains a database of both market value and performance information to develop the Vehicle Performance Index. In order to compete, all vehicles must maintain a Vehicle Performance Index of 500 POINTS or less, as described in Section 4 of ChampCar's Basic Club & Competition Rules (BCCR); or, maintain a Vehicle Performance Index of between 500 and 1,000 POINTS with the understanding that these vehicles will receive penalty laps."

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1 hour ago, Hayne said:

 

Price is in the formula for determining VPi.

 

"Vehicle Performance Index

All competing vehicles will be assigned a Vehicle Performance Index (VPi) by ChampCar. The Vehicle Performance Index is a POINT value that is developed and based on the General Market Value of your car... PLUS... a Performance Evaluation of your car. While some vehicles may have a very low General Market Value, they have a very high Performance Value. Similarly, some vehicles may have a very high General Market Value, but they are considered gutless-wonders. ChampCar maintains a database of both market value and performance information to develop the Vehicle Performance Index. In order to compete, all vehicles must maintain a Vehicle Performance Index of 500 POINTS or less, as described in Section 4 of ChampCar's Basic Club & Competition Rules (BCCR); or, maintain a Vehicle Performance Index of between 500 and 1,000 POINTS with the understanding that these vehicles will receive penalty laps."

I get it but if you want a true "cheap racing league" actual cost would be the way to go...  Not $500 mind you but say $3500-4000 (less safety gear) I think 3-5 is the range we all have in our cars by the time it is said and done. 

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