What to look for before buying an SR20DE Autech?

[GoldHawg]

I took the clutch out today; looked in pretty good shape. I'll go ahead and replace disc since its out, but it seemed like only a little wear towards the O.D. of the disc. But since I'm not used to changing clutches, this may be a lot. I was able to get the clutch disc #; it was a Nissan 91F14, indicating this autech was made after 00. Reading online, the Autech clutch disc can be the same as the one in the S13/S14 since its sprung. This one seems cheap enough:
http://www.ebay.com/itm/EXEDY-CLUTCH-DI ... Ig&vxp=mtr

Any comments on the condition of the flywheel/pp?

[pebbles]

Ive swapped a few clutches back in the olden days. Dont know didley about autech.
So i dont know if the pp and flywheel are plated for one time use, or if those are hotspots.
No idea if the flywheel can be turned or not dimensionally, but if it is possible, I would recommend it.
I would also recommend replacing the pp as well.
Just an opinion.

[greydog]

I hate to take off metal if it's not necessary.
I'd clean with carb cleaner. Glue some 180 grit to a smooth block and sand both pp and fw. then I'd put a straight edge on them in several places. If I don't see light under the straight edge, I'd use 'em as they are.
Neither shows the blue marks I've seen on bad clutches.
Dan

[syne']

You won't be able to use the beautiful Autech headers, ..

Hey spriso, you mentioned once cutting the steering column and adding some U-joints to get around the headers. Could that work on these headers to save them ? and if so has anyone done the steering column mod ?

I ask this because I'm also interested in an s15 autech swap.

[GoldHawg]

Once I get my engine on the mounts I'm going to put the header in and I'll take some pictures to show the interference--should be in the next month I have that up on my build thread. I think Michael also said it hits the frame.

[syne']

Once I get my engine on the mounts I'm going to put the header in and I'll take some pictures to show the interference--should be in the next month I have that up on my build thread. I think Michael also said it hits the frame.

sounds good Goldhawg! I'm glad i get to see this autech in progress, i've been waiting for someone to do this swap. By the way did you end up going with the 5spd instead od the 6spd ?

[RCMike]

The Autech headers are so pretty, but there are so many things in the way to try to use them.. And I would strongly recommend against adding u-joints to the steering.

[spriso]

Autech Headers, and why you need to forget them...

The beautiful stainless headers found on the Autech S15 SR20DE engine are a work of art:



I was so in love with these back in the day, that I actually bought a new set thinking that I could convert them to be used on one of our 510 or roadster swaps. With its investment cast flange, to generous stainless pipes, it is a lovely piece that would look amazing in one of our Datsuns. Alas, it was not to be.... Due to them being designed to use on a RHD car, we run into serious interference on the LHD cars here in North America.

A few years ago, we put an Autech S15 SR20DE into a Mazda Miata, and even on that car I had to massage the engine compartment to get it to clear-- this is a good reference shot to see how far out they stick:





All that beautiful piping will run into the frame rail, the steering shaft, and the frame down below...

If you really must have a header, then you will need to find something (or have a custom set of headers built) that will clear the steering shaft-- our best solution that we have found is a Nissan Primera manifold, but even that needs a ton of work to make it fit:



The outlet pipes are too long (as it is intended to run across and under the bottom of the engine as it was designed to work in a FWD application). So, it needs to be cut off about half way and new outlet pipes built with a collector and then a 90-degree turn to make it into the frame hole.

Stock collector on the Primera manifold that needs to be cut off:



What is nice about the Primera manifold is that it will just barely clear the steering shaft (cylinder 3 is the problem) -- and with a bunch of work, you can really make it look good-- here is one we did on Mikey's car:



So, that is what our experience has been with this manifold-- but I am eager to see other people's solutions!

Michael

[RCMike]

So, that is what our experience has been with this manifold-- but I am eager to see other people's solutions!

Michael

Nice write up!

The solution for my car was to buy a flange and have a header built from scratch, that did what I wanted. We used motorcycle tubing to get the bends I wanted, and dimpled 2 tubes to clear the steering.. Before that, on the stock motor, we used the SE-R manifold, which fits, easily, and works..

[syne']

NO FAIR!!!! lol those headers are so lovely looking ! so is the autech worth it without the headers and 6spd? it is fairly expensive.

[spriso]

syne' wrote:

NO FAIR!!!! lol those headers are so lovely looking ! so is the autech worth it without the headers and 6spd? it is fairly expensive.

There are several things to consider when looking at an Autech engine:

1. Horsepower: The Autech SR20DE engine is rated at 200ps (just under 200hp), which is 35 more ps (hp) than the normal SR20DE engine. Horsepower is not free-- so Autech had to get that power from somewhere-- where did it come from? Most of the horsepower difference is in compression. The Autech engine is a 11.95:1 ratio compared to the 9.5:1 ratio that a standard SR20DE has. So, how do they make that 11.95:1 compression ratio run on pump gas? you ask... well, in Japan, you can buy 100 octane fuel at the pump, compared to our 92 octane (or 91 in California) premium unleaded gasoline. If you want your Autech engine to live here in North America, you will either need to de-tune the ECU, and still use some octane additive, or you buy some very expensive race gas... otherwise the party won't last very long.

2. The Autech engine is a hand-built tuned engine-- They put all the goodies in it-- aggressive ECU tune, sodium filled valves (found in the SR20DET engines, light weight chromemoly flywheel, and the 6-speed transmission. The exhaust is a 2 3/8" version to get it to breathe... All of this comes at an expensive price premium, as they were sold in very limited numbers.

Is it worth it? Hard to say. We can't use that beautiful stainless header as it hits the steering shaft-- so we have found it might just be easier to buy a S14/S15 SR20DE engine and add the 6-speed to it. Yes, they are fun, the Autech powered Miata we built is a blast, but the owner is always on the edge worrying about detonation and gas quality-- where we just beat the living daylights out of our regular SR's without that worry...

Your mileage may vary, but that's my .02 Yen.

Michael

[syne']

WOW, you're really making me think twice about getting an autech. Sounds like it wouldn't make a good DD engine. i would hate to have a such a nice tuned engine be suffocated with all the restrictions we have to do just to run here in the US.

thanks for all the great info spriso.

[sfdaugherty]

Regarding the higher compression. . . Doesn't Rcmike run about 13:1 in his sr20de with the neo vvl conversion? He drives the heck out of that thing at 8000-9000 rpms. I'm sure he or Kevin D can weigh in on how they deal with the high compression. In addition, many sr20dets have been tuned to produce way more boost than stock and I haven't heard of the need for race gas even with the higher cylinder pressures.

Just curious.

Shannon

[spriso]

Shannon wrote:

In addition, many sr20dets have been tuned to produce way more boost than stock and I haven't heard of the need for race gas even with the higher cylinder pressures.

SR20DETs which run more boots typically have larger CC displacement injectors, a MAF change (to a 300ZX or Cobra unit), and computer remapping to take care of the additional fuel, timing, and air needs. The Autech engine could be retuned the same way if you can find a tuner to crack the S15 ECU or run a stand-alone system. On the Miata project, we ran the engine off of a remapped KA24DE ECU with modified fuel and timing maps to match the local fuel requirements.

I don't know the specifics of what Mike's VVL engine is running compression wise, but we know that it has had extensive tuning time with new computer maps to optimize engine performance.

Michael

[RCMike]

RCMike's motor was built with 12.5:1 pistons, then both head and block were decked after the mods were made to allow the parts to mate. So close to 13:1 is correct.. It is wild how different this made it, compared to the stock motor, which is SO MUCH fun, so happy to take abuse..

I asked for it to be capable of running on 91. When I asked for this, the tuner cried, just a little bit..lol.. It will run on 91, assuming I am reasonable with it. regular around town, and highway driving, I will run 91 straight. I CAN make it ping on 91 if I am not thinking about it. 91 with octane boost makes it bulletproof on the streets. Low RPM and full throttle on an uphill? no problem.. Spirited canyon or backroad driving will not cause problems, it just runs..

For track use, I run 100 oct.. Otherwise, around lap 3 I will start to hear pinging as everything heats up inside.. It is cheap insurance.

I am planning to shift it to a flex fuel system soon, to allow the motor to use higher octane fuel to make more power. Our tuner wanted e-85 the minute he heard the motor was close to 13:1.. But I told him it had to be useful for long drives through back country, where 'fuel' might not be available. So he is really happy that I want to go to flex fuel. Should be interesting to see what the fuel will do to power..

But Michael is absolutely right, this would not be possible without a good tuner, and a modified (or aftermarket) computer to make it happy. Same thing with the big turbo motors. They need time on the dyno, with an experienced tuner, to make the maps clean enough that they can take the added boost safely.

Stock motors with stock computers? Hook it up and start it.. it runs..