AlanG

8000rpm.

Lateral Performance

iTrader: (20)

Oh, ok. 8K on the PPG with 4.44's would normally give 136-140mph in 4th, but the 3.9's are far better overall.

Very small wheels, or wheel spin


Mark.

AlanG

Oh, ok. For more accuracy, the car crossed the line at 7700rpm, but at that rate of acceleration, it's as near as dammit on the rev limit. Ideal for the 1/4 mile though...

I see your figures as being typically optimistic Mark At 8000rpm i only see 4th good for 134mph, so 7700rpm is 128mph, which is probably about right for the spec the car was in at the time. Average terminals back then were around 124-126mph.

Lateral Performance

iTrader: (20)

LOL..............

134mph would be on a pretty small diameter wheel, 600mm on my gear calculator.

Anyway, you need to change your "location", to "Used to have"


Mark.

AlanG

PMSL!!

A 17" wheel is 431.8mm in diameter. Add to that 40% of the tyre width (in this case 215mm) = 86mm in tyre height (x2).
That gives a grand total of 431.8+86+86 = 603.8mm in diameter. (for a 215/40x17" set-up)

So erm.... yeah. Well.... I suppose 17's are a bit small nowadays....

I like the get out clause... "Anyway, you need to change......."

Your right about the used to have though.

AlanG

{snigger}
Anyway... Forget comparing horsepower and times, let's compare calculators!!

wrx450

I am a bit confused. I always thought and over the years learnt that shorter gearing helped acceleration and you would end up with a quicker car. Had various V8s over the years and always would transplant the shortest diff gearing possible and would end up with quicker ET and real world car.

I have done the opposite and gone from 3.9 to 4.44

With my 97 WRX with 3.9 gears and GT35 found a lot of lag . In Australia could run 11.5 quarter, but found that was rubbish in traffic. Dynoed at 365hp atw. Was running PAR dog box, not 100% sure of the ratios. Since moving to Cyprus this problem was compounded by the twisty mountain roads. When I say twisty I mean series of very tight bends up very steep inclines and not being able to pull away from turbo diesels 4wd Had to go back to first on many ocassions.

Tried various things including 0.63 turbo housing instead of 0.82 which helped a bit. The fix came in the form of 4.44 ratios, and the car was transformed. Dont know if it is any quicker over the quarter, ran 12.3 at 112mph with only 1.2 bar instead of 2.1bar and normal synchro gerbox. It is certainly quicker in the mountains and traffic with 0.63 housing and 4.44 gears. Am now campaigning in hillclimb championship and will be running PPG straight cut gearbox and 205/40/17 tyres. Will it now be too short?


My peak torque is at 5500 rpm and peak power at 7200pm. I usually change up 7800.

Have I got it wrong?

AlanG

Not got it wrong as such, it's down to what you want to use the car for.

In terms of the 1/4 mile and the way in which my car made power on the GT35R (peak torque at 5000rpm, peak power at 7000rpm), it would have saved an extra gearchange over the 1/4 mile and hence reduced the 1/4 mile time.

Bear in mind that on the 1/4 mile you are continually in the upper rev range, so changing gear would keep the engine "on the boil", so to speak.
Twisty mountain roads like you describe, point to having to reduce speed low enough to negotiate the bend which means you could have dropped out of the power band.
It's horses for courses. I was happy with the 4.444's on the GT35R for road use.

If i were to go into hillclimbing i'd be inclined to change the turbo from a GT35R to a GT30/40 and keep the 4.44's. Would spool up quicker than the GT35R and have more torque over a wider rev range. Ideal for twisty stuff.

wrx450

I was crossing the qtr mile in 4th at 7500, so was just able to save having to go into 5th , with the PAR synchro set. Cant remember back to 2001 with the PAR dogbox, but i think still in 4th as had 3.9 gears.

Yes I will be changing down, to the smaller turbo at end hillcimb season as the GT35 is still a bit big for a 2.2ltr. It requires half a second or so to wake up after each corner and then it wheelspins like crazy when full boost hits at 4000rpm. I would recommend a 2.5 for this turbo if you are doing anything apart from drag racing. I want to see how much quicker car is with PPG dog set and fully seam welded cage and chassis, and bit more experience over last year. Hopefully with the lightning gear changes will have less chance to fall off boost. Then next year run with the smaller turbo.