Engine build ideas, need some help (looooong story)

[bajango]

We'll shoot, maybe I should just throw an L head on the Z24/ Z bell 5sp I also have in the garage. I'd probably have to do something else than GSXR carbs. Or I'll just buy an extra head and have it as a side project too....

[Tom1200]

This topic brings up something that I've been wondering about; I see the dyno figures on L series motors and I'm surprised they are not higher. For comparison my A12GX motor with ports cleaned up, header and fitted with 39mm keihin flat slide carbs made 73 whp. After I added a roarty cam (286 duration 460 lift) it made a shade over 80. The current A15, flat slides, ported GX head with SI tapered stem valves, Delta 278 cam (.420 lift) and 11.5 compression is about 105 whp. If I dialed the timing back it would like run on 91 octane pump gas but drop 5-7 hp. The Keihin carbs were on a D-sports racer making around the 170hp mark, when doing testing they found the flat slides to be worth 5% over DCOE carbs. Note a fully race prepped A15s are in the 150whp range versus stock A12 40 whp.

 

The cam in the 80 whp A12 made it not streetable but the 73whp motor would have been. The A15 trundles around the pits just fine but if you want it to take off quickly it needs revs so it would be semi streetable. Fine as long as it wasn't a daily. Having to run on pump gas would likely equate to 95-100 whp. So again I would expect an L20 to make around 120 whp but I have almost no experiacne with L series street motors.

 

As for price of building the A15; the motor I got sat with water in the sump so the crank had to be turned as well sleeve the number to make the pistons work. I won't include the remedial costs. The custom forged JE piston set was $560, bore $125, balance rotating assembly $125, I got the Keihin carbs with manifold for $250 (an absolute steal), $100 for selection of jets, used Delta cam with lifters $100, header $100, race valve job $200, SI valves $120, the GX head on the car I paid $250 for 15 years ago but my spare GX head was $700 2 years ago and probably $50 in gaskets I didn't have (I have boxes of them). So we are talking $2000-2500 depending on the deals you manage to score. The associated costs on my car were $600 for a mid close box and upgrading to an H190 which was $600 for the needed bits to make it fit plus $1300 more for the LSD. So total for the project $2500 for a road car with open diff and minimum $4000 for a track car.

 

As for performance; At my local track, Spring Mtn Motorsports, I've picked up 10 mph at the end of almost every straight away. I used to arrive at turn 1 at 95ish not it's 103-105 and on the longest straight the difference is 96-98 to 110-111 mph. While not cheap by my cheapo racing standard it wa worth it.

 

Go with the largest bore you can and then focus on getting the best cylinder head you can. Keep the cam streetable. Even if you only pick up 25hp it will be a nice boost.

 

Tom

[datzenmike]

I think my 710 L20B says 110 hp but was BHP rated. The same engine later with NET hp rating was 93. 

 

http://www.datsuns.com/tech/datsundyno.htm

[Tom1200]

Mike I've seen that sheet, it's a good resource, but it's also one of the things I've read that left me wondering why L series motors people are building aren't putting out more. As an example one of,our local racers running SCCA GT-L gets 124 whp with an L16 running the required SIR. The motor was built by Rebello, unrestricted it's makes something like 40 more.

 

A stock L20 making 93 ish at the rear wheels makes sense to me.

 

Bajango mmmm cheap whore that I am I would slap together what I had in the garage and be done with it. Me I like to drive cars not work on them.

 

Due to my bike racing background I am biased towards the motorcycle carbs; I would still play with them, once you have the custom manifold done you can bolt them on. Getting them 100% requires all of an hours dyno even time. I was able to get mine about 98% before putting on the dyno.

[bajango]

I'm gonna try to do the long rod 2.1 build and shoot for gold(if I can find the parts). I'll hold back on the cam and compression a little though and see what happens. I'm gonna build the Z24 in the garage too because I want to compare the power difference.

[racerx]

Sure you can put out more hp but at what cost. Thats why a lot of younger gens will stuff a ka or sr motor and easily get 150 hp, w out a supercharger.

[bajango]

I'm gonna save the fun stuff for my Carina. The Datsun is staying oldskool. I can TRY to make a race truck, but I'll just leave that to the C10R guys.

[Tom1200]

I will tell you this; the extra 20 horsepower may not seem like much but in our car it drops 2-3 seconds off the 0-60 time. When I use the car at track days it slightly pulls a friends stock 99 Miata. Now initially this sounds pathetic until you realize the Miata has 1/4 mile time 6 seconds faster than a stock 1200. It should make a big difference in you truck as well.

 

Tom

[bajango]

It should be close to an extra 30-40hp going from a rock stock l16 to a modified L20b. I'll definitely feel it for sure!

[datsun 160J SSS]

Rotella T great oil . I run this oil in small generators and I swear I see improvements in cooling and longevity.

[bajango]

I'm not sure where I can find Rotella. To be honest I've never really looked for it, but I haven't seen it around either

[datzenmike]

NAPA has it, any auto supply will. Try a Shell gas station but the price will be through the roof. Get the 5 liter jug and you have extra for top ups.

[bajango]

Is there an online resource for rebuild tolerances? My engine build list is getting ever so... diverse... I'm currently looking at Aircooled VW rods and pistons and the rods are close, but I want to check the L20b tolerances before I try anything. I may not buy Aircooled rods because the longest length is 5.7" (shorter than stock L20), but looking around for even more Frankensteined setups reminded me that I don't have any resources/references for tolerances...

[Stoffregen Motorsports]

Doing a little outside-the-box thinking, are we?

 

Keep it simple.

[bajango]

If only finding Z20e and Z22e stuff WAS simple....

[scooter]

Just use l20b rods

[bajango]

I think I've found a good alternative to the rods. I'm not telling till my build thread! It took slot of part number digging

[scooter]

D81 rods

[bajango]

Aren't those Z-E rods?

[datzenmike]

You are in the middle of the PNW full of Datsuns and Nissans. The 6" rod you seek (actually 152.5mm) was used on ALL Z20E (EFI) and Z20S (carb) engines. If it's a Z20 it has what you want.

 

'80-'82 A10 or HL510 cars.... Z20S engine

'80-'81 S110 (200sx) .... Z20E engine

'84-'86 720 truck with 'Mileage Option' Z20S engine.

 

There must be hundreds of thousands sold here. Try Nissan dealer, tell them 12100-N8500 is the part but $100 each. Try NAPA or whatever/wherever and show them the number and the list of vehicles it came in. Phone wrecking yards.

[flatcat19]

If you find a set of Z20 rods with flat-top pistons attached to them...I'll gladly take the pistons off your hands.

[bajango]

Oh. I guess I got it myself all mixed up reading the Jason Grey guide. Oops. Perfect. Thanks guys.

[bajango]

Just bought this setup yesterday for $1000. I think I did good on it. Just about everything there to slap that head right on. Also threw in the SSS grill a "Datsun 1600" valve cover and some other misc 521 parts too. I may not use the 40 DCOE carbs, but I might adapt the bike carbs to the cannon intake. Should I use the mallory dizzy or keep my matchbox on?

 

[racerx]

nice

[bajango]

The guy was too kind! We need a few more Datsun guys like him...