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| Re: L-series engines |
Subject: Re: L-series engines
by andrewjdonoghue on 2002/1/12 10:30:00
L20 crank journals can be ground down - most people wouldn't bother because you just start with a L20 block anyway - heaps cheaper. However there's plenty of people who don't want to let
people know exactly how big their engine really is and cheat this way - it used to be a VERY common trick in Class N rallying in South East Australia (capacity restrictions and all that).
The point here to Mareo was the originality and the sentimental value of the car, not doing things the cheapest way....
The blocks can be taken out a bloody long way beyond what is considered reasonable. Toyota Corona Pistons (88 mm instead of stock 83 mm) used to be an old favorite for oversize bores. 120"
overbore was never a problem on L16 or L24 motors. Bigger is possible, but at signifcant cost and risk. Strangely with a 5mm overbore your stroke to bore ratio comes out pretty good....
Even using the 88mm pistons brings you out near to 2250cc using a stock 20b crank, let alone one with increased stroke (hey - if you're regrinding the base circle of the crank anyway!!).
Doubt me not people, the money some of these rally guys were throwing away was enormous - and eventually led to changes in rules of the class to ban such cars.
L18's were a stroke job only of L16's so using an L18 crank in an L16 gave L18 not L17.... At least that's the way it was with Australian models. Likewise L26 was only a stroke job of L24 (
(83*73.7 to 73*79mm).
2150 is considered a "normal" overbore size, and I have seen this used on L series blocks running in excess of 25psi boost (T3, T3/4 hybrid and T4 turbo) with no problems.
A friend of mine was running such an engine in their bluebird until they lit it up just a bit too much at a roundabout one day....
Aussie Zoom readers would have seen a SA 1600 running a 2150 twin turbo setup in an L series - Greedy's yellow one - later shown with blue paint and an SR20 conversion.
As far as U20's being the basis for L24 engines, that's to do with the whole development from Roadster to the Z which replaced it. Note that the L series never ran anything like those carbs
until the Z came out, but twin Su's and Solex's were used on the 2000 roadster. I've got the interim design drawings from Roadster to Z in some books here.
I know there were L20 and L23 motors around at a similar time - check the carburetion and cam profiles compared to the Z....no similarity at all.
Note Japanese models of the Z are still called the Fairlady, and early Japanese Z's had a number of different engines in them, including a number of different 2 litre SOHC, DOHC models not
seen elsewhere - such as the 432R DOHC S20 engine, with triple 42DCOE webers (from the standard 2 litre triple solexes).
Checking out a few internet links shows significant differences between Aussie delivered roadsters and American ones, but I think you're right about the R16 not the J16 - J series engines
were used in a Datsun 1500 and 1600 utes of the same error and may be the cause of my confusion - we wrecked one and rebuilt one the other day at a mates wrecking yard. The two are different
engines, but I dunno how similar they are or anything about parts compatability - there's very few of either of these types of engines left in Aus.
Did america get the 3 seat roadster?
Anyway it's been a long time since I've seen much of the inside of a roadster with a genuine engine - something like 8 years since I helped a mate restore one. the few I've had a good look at
since then have got L16's, L18's or fuel injected jobs.
Maybe if I sell the ute I'll get one.
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