Thanks Rob..i`m barking up the wrong tree with that question i think.Try again
What i would like to do is change the gearing in my Astra Gsi to the same as i had in my old F reg 1.8 Sri.Rob assures me that an f20 cr is just a beefed up f16 cr but they must have had different final drives?Does any one know the final drives for the two,and most of all,could the f20 final drive be replaced with the f16 as this would make 5th in mine far more usable?
you are right about the F20 and F16 being identical. Your XE engine comes with a box anyway dont it ? Why dont you save the hassle and just run with the F20, it will take anything you can throw at it. And with the relatively low torque of NA engines you can hammer it till the cows come home.
Top speed`s not too high....i`d like more.Ya dont think that mine is gona hit 7800 in 5th with an F20 do ya?I could lower the final drive which would make 5th more usable and still have the same top end..just use a few more revs to get there.
yeah i know what you mean mate. lower the FD ratio and the revs will be higher in all gears, which makes 5th better for accelerating on the motorway. same 145mph top speed or whatever, you'll just be at 7500 instead of 7300 (say)
didnt put any thought into those figures, just illustrates a point
what you really need is a better speedo mate, that needle was going banana shaped
try a digidash or turbo clocks maybe
Ive just built my Astra turbo back up with an F16 box!!! Its not finished yet so I havent run it!!! When I had the F 20 in it I would see 154 mph but as you dont get to do those sort of speeds all the time I thought I would go with the F16 for better take offs.
Have I made a big mistake here???
i wouldnt try and break the box cos the shaft could get pushed through the flywheel. bits fly everywhere if it goes kabloooey in spectacular style.
normally the cogs just get shredded, but a lad i used to know had a track mini and half the box ended up in the engine lmao dunno what happened tho, i was too busy laughing at him crying as it was taken off the trailer
Yeah..does go a bit bannana shaped.That was at only 6500 which eqates to just under 140 in the real world!I really dont think theres much more to go after that unless your on a down hill runway even with 190+ bhp which makes me wonder if the Mk3 astra has got the aerodynamics of a brick?
Originally posted by 16vastra what you really need is a better speedo mate, that needle was going banana shaped
try a digidash or turbo clocks maybe
Erm i wouldnt rely on a digi dash either, i did a bit of a high speed run in the early hours of this morning on the way home from southend (3am ish) I topped out in 4th at 130 ish, went to fith, dash crept up, 135, 137, 140, rev counter starts flashing (indicates redline of standard ecu 7200rpm) revs climing, digi dash start flapping, 136, 139, 135. Bastard, well, i got to about 7400-7500 in 5th, i dont know what that equates to taking into account gear ratios etc. But it must have been 145 ish, maybe more.
Well...thats odd,oddball.7500 rpm in mine would equate to around 160 mph.Mine wont rev above 6500 in top(even though it seems that it is).I can get 130 in 4th easily and then 140 in 5th in no time but not much after that.****....if i ever saw 7000 in top i reakon id well cak me pants
hmmm, well unless my tacho is wrong, but it was screaming, with the digi rev guage flashing at me. I used a nice little downhill section to get me up to speed but the actual speed run was up an incline as its the only straight bit of motorway i know.
plus my 16's are slight smaller rolling radius than the original 14 inch and tractor tyres.
anyway, i asked richie, he told me the theoretical top speed of my car with F20 and 7750 rev limit was 156, so maybe your source for the ratios is out ? 7400rpm at about 145 seems to work with the above.