wwe_champion Posted March 10, 2004 Share Posted March 10, 2004 Gday all, i just have a question. My mate and i both have 180sx and both have RB20's in them. Mods wise they are very similar in that there isn't really any. But when we are travelling at similar speeds are revs are very different. E.g when im doing 100km/h my car reads out that im doing 4500rpm while my mate at the exact same speed is only doing 3500rpm and they are both in 5th gear. Could anyone tell me the possible reasons for the difference in revs and could this be a problem. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/ Share on other sites More sharing options...
sewid Posted March 10, 2004 Share Posted March 10, 2004 RB20's? Sure you dont have SR20's? Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-718382 Share on other sites More sharing options...
MJ Posted March 10, 2004 Share Posted March 10, 2004 im sure he knows what engine he has they both got swapped for rb20's by the sounds of it. Sorry i cant help ya mate Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-718402 Share on other sites More sharing options...
robbo31 Posted March 10, 2004 Share Posted March 10, 2004 do u have different diff ratios??? Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-718424 Share on other sites More sharing options...
Pekatu Posted March 10, 2004 Share Posted March 10, 2004 yeah it would either be diff ratios, gearbox, or you tacho is wrong, my rb20 sits at about 3000 ish at 100kph Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-718454 Share on other sites More sharing options...
gtrken Posted March 10, 2004 Share Posted March 10, 2004 Some Silvia/180sx's had 4.3 diffs and some had 4.1's. If it is a Jappo dorifto style it may even have 4.4 or 4.6's in it along with an LSD. Cheers Ken Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-718470 Share on other sites More sharing options...
usuckpoo Posted March 10, 2004 Share Posted March 10, 2004 another possibility is that you're running ex-auto diff ratios...although im not too sure what the exact ratios are... Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719212 Share on other sites More sharing options...
sewid Posted March 10, 2004 Share Posted March 10, 2004 im sure he knows what engine he has they both got swapped for rb20's by the sounds of it. Sorry i cant help ya mate yeah youd think so, but he said he and his friend have no mods. why would you go through the effort of swapping the SR20 for the RB20 anyway? If you were going to swap to an RB you would at least go for the RB25. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719341 Share on other sites More sharing options...
blind_elk Posted March 10, 2004 Share Posted March 10, 2004 Can we safely assume you are driving side by side, so you know you are both doing the same speed. sewid - maybe RB20s are a lot cheaper than RB25s. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719349 Share on other sites More sharing options...
MJ Posted March 11, 2004 Share Posted March 11, 2004 yeh rb20's are heaps cheaper then rb25's and they might not have been sr20's they could have started life as a ca18 which was getting old. Yeah now i think of it if the car was auto it will have a different diff ratio too. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719486 Share on other sites More sharing options...
wwe_champion Posted March 11, 2004 Author Share Posted March 11, 2004 would it be best if i could get the ratio changed? Who is best to do this? Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719584 Share on other sites More sharing options...
Mrman Posted March 11, 2004 Share Posted March 11, 2004 Why would you want to change it. If you have an auto diff ratio and your car is manual it means you will have a quicker take off then your friends car. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-719925 Share on other sites More sharing options...
wwe_champion Posted March 11, 2004 Author Share Posted March 11, 2004 In actual fact his is quicker, why i don't know they are roughly both running on same psi, but his definitely is quicker. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-720111 Share on other sites More sharing options...
dojobi Posted March 11, 2004 Share Posted March 11, 2004 Just to check that the tacho isn't wrong (as 1000rpm seems like a huge amount more for a 4.3 diff over a 4.1 one), do the engines sound the same when they cruise at that speed? I mean does your one actually sound like it's doing 1000rpm more than his? Since yours is slower, it does sound like your diff isn't some super high ratio one. Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-720198 Share on other sites More sharing options...
wwe_champion Posted March 13, 2004 Author Share Posted March 13, 2004 Im not the most knowledgeable when it comes to the mechanical side of cars, but can someone please explain what the difference is with the diff ratio and how it effects the car. Is it related to the gear ratio. Im sorry if this is a dumb question but i don't really know. Tah Link to comment https://www.sau.com.au/forums/topic/36017-whats-the-reason-for-the-difference/#findComment-722587 Share on other sites More sharing options...
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