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SR20DE/KA24DE Roadster Engine Swaps

To: datsun-roadsters@autox.team.net
Subject: SR20DE/KA24DE Roadster Engine Swaps
From: michaelspreadbury@attbi.com
Date: Mon, 01 Apr 2002 17:28:22 +0000
Hi Alan,

I have a few spare minutes this morning, so I thought I 
would catch up on a little e-mail. Your post brings up 
lots of good points, and really when you think about it, 
all engine swaps come down to personal preference for 
what is going to work best for a persons skills 
tenacity, mechanical ability, and their desire to do 
something different. 

The KA24DE found in the Nissan 240SX makes for a great 
swap into a Datsun Roadster. I have seen several of 
them, and the owners that I talked with have all been 
very happy with their conversions. The KA-series has the 
advantage of easily sourced parts, and now that lots of 
240SX owners are pulling them out of their cars to 
install the SR20DET engine, they are cheap and easy to 
find on the used market.

With its 2.4-liters of displacement, the KA24DE makes 
lots of torque, and as we all know, torque is what makes 
our cars fun to drive. However, a lightweight car like 
the roadster still responds extremely well to the 2.0-
liter SR20DE. 

However, ask anyone who has buzzed both a KA24DE and an 
SR20DE to their respective redlines and I think you will 
find most will agree that the SR20DE is a much more 
refined engine package. The SR is so smooth all the way 
to the redline, it really is remarkable. Another 
advantage of the SR20DE is its all-aluminum 
construction unlike the KA24DEs aluminum head, iron 
block arrangement. 

Both engines use nearly identical engine management 
systems (my SR20DE is running on a KA24DE harness and 
ECU), and the gearboxes are the same internally (though 
the SR20DE has a different bellhousing).

RWD SR20DEs can be purchased very cheaply from engine 
importers, I have seen them as cheap as $500, all the 
way up to $2000 depending on what you are getting. Of 
course you would want to buy as complete of a package as 
possible, be sure to get the engine/transmission, and 
most important, get the starter, it is unique to the SR-
family. I like to estimate ~ $1200 for a super clean, 
low mileage power train.

Using a FWD SR20DE can (and apparently has) been done. I 
have never seen photos, so I really cant comment, but 
since RWD SR20DEs are not that difficult to source, I 
would not waste my time converting a FWD SR20DE engine 
into a roadster. Why invest your time reinventing the 
wheel?

The notch that is required to clear the front sump oil 
pan goes to the first set of welds on the inner 
structure of the crossmember (about 1.5 in from the 
outside edge). If you have ever cut one apart, you will 
see that there are a couple braces welded into the 
center of the crossmember. Basically, the notch we make 
butts up to the first reinforcement. The notch is mostly 
to ease installation of the engine and transmission, I 
have heard of people just smashing in the crossmember to 
clear the front pan, but I prefer to remove the material 
and weld in a new cap rather than using a hammer to gain 
the clearance. With this material removed, the engine 
and transmission install into the Roadsters engine 
compartment very easily. 

Anyway, enough rambling. Both the KA and SR make a great 
swap into a roadster, my preference has, and always will 
be with the SR-series engines, and I think if you ever 
get an opportunity to drive a roadster with this engine, 
you would agree! I have yet to have someone take my car 
for a spin that was not sold

Michael Spreadbury
1966 Datsun Roadster (with SR20DE power)
1969 Datsun 2000 Roadster (soon to be with SR20DE power)
1970 Datsun Bluebird SSS Coupe (SR20DET/6-speed project)



>Michael,
>I really appreciate you taking the time to respond to 
my question. I will
>ask a couple more if you don't mind. The reason I was 
considering the
>sr20det was the increased HP. With my admittedly 
limited knowledge of this
>engine, it seems to me that the ka24de would make more 
sense than the NA
>sr20. I know the ka's are more readily available and 
cheaper. I think also
>(correct me if I'm wrong) that a ka24de makes more HP 
than the sr20de and
>have heard several people on the list speak of how 
simple of a swap it is. I
>don't recall anyone saying that the crossmember had to 
be notched (although
>maybe it does since these 2 engines are a direct swap 
in the 240sx) to
>accept the ka. However, at the same time, I know there 
are many 240SX owners
>opting to remove the ka in favor of the sr, something I 
don't really
>understand. I guess I'm sort of rambling here, so I'll 
just list out a few
>questions for you.
>
>What are your feelings SR vs. KA?
>Are the transmissions interchangeable on these two 
engines?
>Are you aware of body or frame mods necessary for the 
ka?
>What do you consider a fair price for a 40,000 or less 
mile SR20de?
>What kind of mods would be necessary to use a front 
drive engine in a rear
>drive application?
>How much of a notch was required in the crossmember for 
the SR?
>
>Again, thanks for your time.
>
>Alan Horton
>
>P.S. That is a beautiful job on your 66.

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