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| L18 engine build advice please http://www.ozdat.com.au/forum/viewtopic.php?t=3936 |
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| Author: | fr3ak [ Sat Dec 04, 2004 8:20 pm ] |
| Post subject: | L18 engine build advice please |
Hi. I've got a 180BSSS which my Father and I will be sharing for weekend racing. This includes clubsprints (both of us) and drift (me). I've bought a motor with, what i believe to be, a fairly 'worked' head. The only thing not touched is the valve size. However, the cam is only 270' duration with 0.305 inchs of lift. This is the same size of cam in my Dad's 'street' 180BSSS. We had his car dyno-tuned on Thursday and then took it for a road test. My Dad liked how i goes now (compared to standard), but i still reckon it's gutless. Obviously we don't want 2 of the same car, so how should we go about getting my engine more suitable for track work? The bottom end will get new bearings etc and bigger flat-top pistons. Now comes my next question: How hard can we rev the standard crank? This (and along with the fact we only have 40mm Delorto's) will determine what cam goes into the engine. I don't really want to fork out more cash for too many more parts, and as such, want to keep the Delorto's. Advice and experience needed as i'd like to compare what you guys think, to what my engine builder thinks. Thanks For more details on engine see my website *below* |
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| Author: | fr3ak [ Sat Dec 04, 2004 8:50 pm ] |
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I've got a book called: How to HOTROD and RACE YOUR DATSUN It says the crank only has problems when "the racer who twists his engine to 6,000 RPM or more for hours on end." Is this true? If you only rev it hard for a short time, how far can you go over the 6,000RPM limit? The crank will likely get the once-over to smooth its surface etc. How long do last then? They are forged from he factory too! Is this any consolation? |
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| Author: | fr3ak [ Sat Dec 04, 2004 9:08 pm ] | |
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a S2 Bluebird crank is a fully counterweighted steel crank from the factory... thats the way to go
So i bolt this in and go racing? Or is it only for a S2 Bluebird?
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| Author: | fr3ak [ Sat Dec 04, 2004 9:47 pm ] |
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I've always wanted to use the L20 bottom end, but cuz the car is duel-purpose, it has to stay 1.8lt (historic racing dream of my Dad) So the question remains: How far can i rev the stock crank, and therefore, what cam do i choose? |
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| Author: | Nozzer [ Sat Dec 04, 2004 9:54 pm ] |
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A guy who tweaks spanners for a Supercar team once told me that the best rev limit for a stock bottom end is whatever the stock redline was on the car. Not knowing what that was on a 180B SSS I cant say with certainty, but that would be a working point maybe. |
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| Author: | fr3ak [ Sat Dec 04, 2004 10:32 pm ] | |
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A guy who tweaks spanners for a Supercar team once told me that the best rev limit for a stock bottom end is whatever the stock redline was on the car.
![[ img ]](http://memimage.cardomain.net/member_images/8/web/488000-488999/488691_54_full.jpg) I like that logic (especially in this case) and if i weren't swayed by anyone else would adhere to that. Does anyone out there circuit race their L18? I'd also like to know your suspension rates 
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| Author: | lampy [ Sat Dec 04, 2004 10:59 pm ] |
| Post subject: | |
hey guys the l18 crank properly prepared can rev to 9000+, look at the BRE 1600 race car, that rev's easily to 9000. There is a video on dimequarterly of it on the dyno at 9000. But a l20b is not going to rev that high due to the longer stroke. use toyota flatops 89mm on a shotpeened and magnafluxed bottom end with a high comp head and large valves/ports. For road racing use the wildest cam you can find and a vernier cam gear to dial it in. You will also have to recurve your distributor. I belive cam timing and distributor curves are really the key with l series engines and big cams. Buy the books "How to race and hotrod your datsun" and "How to modify your nissan datsun ohc engine" with these two books you will be able to build a very compeditive engine |
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| Author: | jdmdatsun510 [ Sun Dec 05, 2004 12:27 am ] |
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What power did your SSS make on the Dyno fr3ak?? |
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| Author: | fr3ak [ Sun Dec 05, 2004 11:09 am ] |
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My Dad's Datsun 180BSSS made 52kW's at wheels It has: Extractors, Twin SU's, mild CAM I actually told him it's making standard power!  But i doubt too many owners dyno's their cars 30 years ago, so i have no clue what they made stock standard when new.The aim of the dyno session was to get a flat a/f graph. We got close, but we're still looking for more needles to get it better. And yes, this current tune is superior to Stewart Wilkins' effort. |
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| Author: | jdmdatsun510 [ Sun Dec 05, 2004 3:23 pm ] |
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Is that a 4 or 5 speed manual ??? |
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| Author: | fr3ak [ Sun Dec 05, 2004 3:37 pm ] |
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5 speed. Why do you ask? Also, i've read my Datsun book. It says reving over 6000 limits the life of the cranks, and they should not run over 7500 because the centrifical forces at that RPM cause the oil to leave the crank, and then it dies. They suggest plugging the oil holes to prevent this. I won't rev mine above 7500rpm. Problem solved? Pick a CAM that makes power before this limit a good idea? I think so. |
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| Author: | jdmdatsun510 [ Sun Dec 05, 2004 3:40 pm ] |
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only asked cause my 180B SSS makes 10 more rwhp and its a auto. I might be putting a manual in it soon . 25/65 Cam is great. with the correct springs you could rev it to 7500, but it aint gonna be making power that rpm, chances are power will drop off before 6000 rpm. So unless you in top gear there would be no poiint in revving it to 7500 |
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