Snagger Posted December 15, 2019 Share Posted December 15, 2019 16 hours ago, youngengineer said: 70mph at redline yes. But who drives around at redline? Again, how are you calculating your speed? My friend would constantly boast about doing 70mph in his series 2A fitted with a 200tdi until he blew it to pieces driving up from leeds to Scotland. Again his speedo would show 70mph but in reality it was not close to real speed. I have had the speedo calibrated accurately and tested it against a few other vehicle’s speedos and radar trap speed displays. It’s is within 2%, so I know what it’s doing, and even with the 12J engine and a standard transmission plus overdrive I was able to get 85. If yours is topping out at 45, running out of revs you have a very nonstandard transmission or running out of torque something is desperately wrong with the engine. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted December 15, 2019 Share Posted December 15, 2019 Is that a 1 tonne chassis? My 109 with standard petrol gearing feels slightly uncomfortable at 60, tested against GPS (waze on the phone). At this speed you can have a conversation, albeit with slightly raised voices. This TDi 200 has a performance head from Turner, a performance IP from Diesel Bob, and defender turbo on a disco engine. It has a cheapo air filter cone (horrid thing), and a roof rack and is running on BP ultimate. The intercooler is a Chinese "performance" eBay special form a Fabia RS. I've lined the bulkhead and bonnet with building materials (Flashband) as I see no difference from bitumen from a builders merchants and bitumen from an expensive car audio supplier at 10 times the price. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 15, 2019 Share Posted December 15, 2019 60 was about as much as I would ever push my old 2.25 petrol lightweight, and wouldn't sit there for long, 50 was much more comfortable. But it is all relative Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 16, 2019 Share Posted December 16, 2019 On 12/15/2019 at 6:29 PM, Bowie69 said: 60 was about as much as I would ever push my old 2.25 petrol lightweight, and wouldn't sit there for long, 50 was much more comfortable. But it is all relative What size tyres did it have? It would make a difference if it had 6.00s or 6.50s, (or the speedo for those with 7.50s, so was underindicating). Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 16, 2019 Share Posted December 16, 2019 I forget now, was a while back! It wasn't 7.50s for sure, but never looked as small as 6.00, so I guess 6.50s. It would keep doing 60, I just didn't like doing it! Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 17, 2019 Share Posted December 17, 2019 Standard for Lightweights was 6.50, until late on where they used 7.50s and had to add spacer tubes to the back of the bumper to push it forward of the front cross member to stop the tyres hitting it (1/2” or so). That’d probably give a 10%+ variation over 7.50s (or the indicated speed if you had the bigger tyres but hadn’t recalibrated the speedo). Still, you’d have gotten more than 45mph unless something was broken! Quote Link to comment Share on other sites More sharing options...
youngengineer Posted December 18, 2019 Author Share Posted December 18, 2019 (edited) On 12/15/2019 at 5:00 AM, Snagger said: I have had the speedo calibrated accurately and tested it against a few other vehicle’s speedos and radar trap speed displays. It’s is within 2%, so I know what it’s doing, and even with the 12J engine and a standard transmission plus overdrive I was able to get 85. If yours is topping out at 45, running out of revs you have a very nonstandard transmission or running out of torque something is desperately wrong with the engine. Theres nothing wrong with the engine. It will go to redline. Compression is great on all cylinders. I'm running a hybrid turbo, loads of boost and fuel mods. Spins the wheels up all day. I'm just not comfortable driving around with the needle bouncing off the limiter. I dunno, maybe I need to invest in ear defenders but it does not feel or sound good. Your getting 85Mph with 3.54 diffs and an overdrive I assume? Thats quite different to what I had which was no overdrive and standard diffs. So comparing apples to oranges really. If you really are running 85Mph on 4.7 diffs, series box and overdrive then you must be running some outrageously large rubber! Edited December 18, 2019 by youngengineer Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 18, 2019 Share Posted December 18, 2019 No, I got 85 with standard transmission and diffs with overdrive and regular size tyres (7.50 while I had the 12J engine, 238/85 with the Tdi in standard tune). Not nice on the ears, but nothing blew up. Cruising with those specs is easy at 60-65mph and is a long way from harming the engine. With the 3.54 diffs too, then it was still fairly calm at 70-75, but it would rarely reach that speed and any incline or headwind slowed the vehicle enormously. It was a horrible gearing combination. Quote Link to comment Share on other sites More sharing options...
youngengineer Posted December 18, 2019 Author Share Posted December 18, 2019 (edited) 85Mph on 32" tyres (assuming 238/85 used), series diff, series box & TC and overdrive gives you around 4800RPM (according to Ashcroft) so something is not adding up. 🤔 Edited December 18, 2019 by youngengineer Quote Link to comment Share on other sites More sharing options...
Chicken Drumstick Posted December 18, 2019 Share Posted December 18, 2019 On 12/14/2019 at 12:00 PM, youngengineer said: 70mph at redline yes. But who drives around at redline? Again, how are you calculating your speed? My friend would constantly boast about doing 70mph in his series 2A fitted with a 200tdi until he blew it to pieces driving up from leeds to Scotland. Again his speedo would show 70mph but in reality it was not close to real speed. Had a 200Tdi in my 88 SIII. Stock gearbox/transfer box and 3.54 diffs. Ran various tyres from 7.00 x 16 thru to 8.25 x 16's. I GPS clocked it at 89mph on the level and it wouldn't go any quicker. I forget what tyres it was on, probably some 7.50's. Would happily sit at 65-70mph if you wanted too. With the 4.7 diffs I forget how it ran, but was more like 60-65mph top speed, but I never tried to Vmax before swapping the diffs out. Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted December 18, 2019 Share Posted December 18, 2019 4 hours ago, youngengineer said: 85Mph on 32" tyres (assuming 238/85 used), series diff, series box & TC and overdrive gives you around 4800RPM (according to Ashcroft) so something is not adding up. 🤔 Might be worth having a quick glance through this thread if you haven't already: Do you know for definite what transfer box you've got because skimming through stuff it sounds like the ratio might be a 1 tonne one. Quote Link to comment Share on other sites More sharing options...
youngengineer Posted December 18, 2019 Author Share Posted December 18, 2019 (edited) On 12/14/2019 at 10:07 AM, youngengineer said: 1-ton box would give me 3900RPM at 50Mph... I'm not even close to 3000 at 50mph. This.. I've definitely not got a 1-ton box. My gearing is perfectly inline with ash-croft calculator. As far as I know, all series have the same high range ratio gearing, 1.15:1. Obviously apart from 1-ton. Edited December 18, 2019 by youngengineer Quote Link to comment Share on other sites More sharing options...
Snagger Posted December 18, 2019 Share Posted December 18, 2019 4 hours ago, youngengineer said: 85Mph on 32" tyres (assuming 238/85 used), series diff, series box & TC and overdrive gives you around 4800RPM (according to Ashcroft) so something is not adding up. 🤔 Something is wrong there. Mine definitely made 85 with overdrive and 4.71s, and that was diesel. It was ragging it on a shallow downslope, but I have crosschecked that speedo in several ways and it’s very accurate. Without overdrive, the same engine rpm would give 66mph. That is a pretty reasonable figure for such a vehicle and consistent with wide experience. My figures are also consistent with other folks on this thread. You need to find out what transfer box you have, what diffs are fitted and what speed you’re actually doing for a given indicated speed as the potential for some previous owner fitting lower ratio diffs or transfer box or a faulty speedo system are not small. Quote Link to comment Share on other sites More sharing options...
youngengineer Posted December 18, 2019 Author Share Posted December 18, 2019 3 hours ago, Snagger said: Something is wrong there. Mine definitely made 85 with overdrive and 4.71s, and that was diesel. It was ragging it on a shallow downslope, but I have crosschecked that speedo in several ways and it’s very accurate. Without overdrive, the same engine rpm would give 66mph. That is a pretty reasonable figure for such a vehicle and consistent with wide experience. My figures are also consistent with other folks on this thread. You need to find out what transfer box you have, what diffs are fitted and what speed you’re actually doing for a given indicated speed as the potential for some previous owner fitting lower ratio diffs or transfer box or a faulty speedo system are not small. You're actually not wrong. I revisited Ashcrofts ratio calculator to double check and it looks like the overdrive numbers and graph are placed seperately lower down on the page. So at 85mph it's showing around 3500rpm which is still crazy high but within the rev range of the engine so certainly possible. Quote Link to comment Share on other sites More sharing options...
Chicken Drumstick Posted December 18, 2019 Share Posted December 18, 2019 I have a gearing spreadsheet I built ages back, before Ashcorfts online one. 4000rpm with 32" tyres gives and 4.7 diffs with stock gearboxes: Roamerdrive 88.1mph Fairy OD = 90.4mph Suspect you'd do very well to actually get to 4000rpm in top though. So I believe 85mph with a bit of downhill assist is possible 1 Quote Link to comment Share on other sites More sharing options...
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