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#1 Velict

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Posted 31 August 2017 - 02:15 AM

My 1987 Nissan Sunny Truck has shipped to the United States. So while it floats towards the land of the free, I want to put a parts list together for an engine rebuild. 

So, I've been looking at datsun1200 website. They're are quite a few posts about A15 engines making or breaking the 150HP mark NON turbo'd. 

I'm really itching to build an A15 with a T50 gearbox. I want to have some occasional spirited driving moments, but usually stick to shows and have good streetability. So that I can get a mass of parts on order, ready and waiting, does anyone have an idea what I need to do to an A15 to get it to dart and scoot pretty nicely? 

 

My guess / research. What I listed below is what I assume will be a definite "yeah duh dude". Please add more items to this list that is required for a darty drivetrain. 

Oversized Pistons 79mm

Ported and flowed head

More aggressive cam, but streetable (where to purchase?)
Oversized Valves (what size? can any engine shop port the head and cut the stems to accept them?) 

T50 Transmission with mount kit/bell mod. (What driveshaft do I need for an extended bed Sunny Truck 1987?)

 

Of course take it to a good tuner for the carb. 
 

 



#2 Lockleaf

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Posted 31 August 2017 - 06:57 PM

I'm pretty sure member Toms1200 builds race spec A series engines. Try looking him up.

Half Pint ('71 510 Goon) http://community.rat...agon/p?=1269361

 

Audrey ('69 Roadster 1600) http://community.rat...rey-the-ratster

 

Tiny Havok ('85 720 DIY built Crewcab 4x4) http://community.rat...ache/?p=1395455

 

720 Shenanigans http://community.rat...20-shenanigans/


#3 datzenmike

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Posted 01 September 2017 - 05:30 AM

My 1987 Nissan Sunny Truck has shipped to the United States. So while it floats towards the land of the free, I want to put a parts list together for an engine rebuild. 

So, I've been looking at datsun1200 website. They're are quite a few posts about A15 engines making or breaking the 150HP mark NON turbo'd. 

I'm really itching to build an A15 with a T50 gearbox. I want to have some occasional spirited driving moments, but usually stick to shows and have good streetability. So that I can get a mass of parts on order, ready and waiting, does anyone have an idea what I need to do to an A15 to get it to dart and scoot pretty nicely? 

 

My guess / research. What I listed below is what I assume will be a definite "yeah duh dude". Please add more items to this list that is required for a darty drivetrain. 

Oversized Pistons 79mm

Ported and flowed head

More aggressive cam, but streetable (where to purchase?)
Oversized Valves (what size? can any engine shop port the head and cut the stems to accept them?) 

T50 Transmission with mount kit/bell mod. (What driveshaft do I need for an extended bed Sunny Truck 1987?)

 

Of course take it to a good tuner for the carb. 
 

 

The closer to 150 hp the less streetable it will be. Think about it. That 150 is probably made at 9,000 RPMs on the track, so just how well will it idle and start in town? Even 100 hp would be pretty hairy. I don't suppose you would care for an L20B transplant?  


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#4 Stoffregen Motorsports

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Posted 01 September 2017 - 08:06 AM

My A12 had 100 hp, but it had a very large cam which meant more valvetrain maintenance.

 

150 hp from an A15...? Well I guess it could be done, but as Mike said, it won't be very fun to drive around town. The only A motors I've built that had that kind of hp were full blown race motors. You've got to ask yourself what it is you're trying to achieve. If it's 150 hp, the A series may not be the right engine. If you want to keep the A15, then that's a different route.

 

Cost wise, getting an A15 to that hp won't be cheap. You will spend probably $2000 on intake alone as carbs are not cheap these days and dual carb manifolds don't exactly grow on trees. Then you'll spend another $1500 on the head porting. The bottom end will not be cheap either. I would guess maybe $3000 on bottom end. A full length header (probably custom unless you can find a Nissan Motorsports header) and a large custom exhaust will be required for that amount of hp too.

 

Then finally, can the trans handle 150 hp?



#5 Tom1200

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Posted 01 September 2017 - 06:37 PM

Velict, I got your PM and will answer it as well but wanted to post up here as well because this is a frequent question for people new to A series builds.Regardless of wheter it's an A12, 14 or 15 the parts are more or less the same.

A full race A15 is going to be 150hp at the rear wheels and isn't even remotely streetable; needs 110 octane fuel and rebuilding every 6-7 hours of run time. For a full race A12 those are between 100 &110 at the wheels. These motors make no power below 5000 RPMs.

The motor in my car now would be somewhat streetable; it's a bit unhappy under 4500rpms but will at least pull away from a stop at 2500rpms, albeit not rapidly. The idle just ok and the gas mileage is poor (9 mpg on track, maybe as hig as 15-18 around town)

We're doing some fine tuning on it and I'm expecting around 110-115hp (currently 105) at the wheels which probably equates to 135-140 at the crank. Here is the spec; A15 76.5mm JE forged pistons, stock crank rods balanced, 14lb flywheel, Delta cam 278 degrees duration .420 lift, Ported GX head, 11-1 compression, SI 37mm intake & 30mm exhuast valves (SI makes them with a narrowed stem to increase port flow), 3 angle valve job, Iskederian dual valve springs, 39mm Keihin FCR Flatslide carbs on custom intake manifold, Nissan header, 210 electronic distributor set to 38 degrees at full advance (no vacuum advance) modified stock oil pump (gives 60 psi pressure) I got some smoking deals on some of the parts so I only have about $2500 in it.

The power is in the cylinder head:

You'll want the GX cylinder head, these will cost between $400 and $700 depending on what's been done to them.

Porting them isn't a huge deal, I actually did mine using a dremel. The biggest issue is the valve seat actually protrude into the port by 1mm all the way around, meaning you have a 2mm smaller port at the valve seat. Just getting rid of that makes a huge difference. Look at the pictures on Datsun1200.com of what is done around the guide / bowl area. After that match the manifold and gasket to the head. Also CC the combustion chambers so they are all the same (you can look this up) I use a piece of lexan and a basting syringe (get it in the kitchen utensils section of Walmart/Kmart etc.)

For valves use one of the Nissan prep manuals specs 38/32mm intake exhaust (as noted above you can use SI brand as the the stems are narrowed so they flow a bit more) the SI valves are 37/30. I do not remember the exact cost but I want to say they were around $150 for the set.

Delta Cams in Tacoma will do regrinds for around $100 (you'll need new lifters) as well as dual valve springs Isky sells them for a-series engines, I think they around $150

Custom JE Pistons with rings wil be around $600; you can go the Subaru Justy route for 79mm in a A15 but by the time you order up two sets have the block decked etc. it's almost as much as just buying custom pistons. Note on an A12 76mm is as large as you can go.

I prefer the Flatslide carbs but I got the deal of a lifetime $250 for the carbs and the custom intake manifold. You can price out 40-44mm DCOE carbs and compare that to having an intake fabricated and using 4 cylinder bike carbs.

For for headers / extractors you can buy the works of art Tomei ones that are a mere $3000 or generic types for $200 used. For a street car it likely won't matter. Use 2" exhaust out the back.

The one part of the equation rarely talked about are the gear ratios; the harder the motor is tuned the more it needs close ratios; a mid close box will do the job for a street car. I have both a mid close and an ultra close ratio 4 speed 56 series gearbox, these are fine for an A12 but the built A15 will eventually break them. I currently use a stock 60 series 5 speed, while I whine about the horrible rpm drop from 2nd to 3rd I recently turned my fastest laps ever with this gear box. The stock box is annoying but apparently not as bad as I thought, my motor is moderately tuned by race standards so I can get away with it.

Last is the rear end; I can't remember what is in the long wheelbase Utes, H165 or Borg Warner. If you're using a 5 speed then using a 4.11 or 4.38 ring and pinion is not a huge deal. A series motors will turn 5000 RPMs for hours on end so the lack of an overdrive won't matter to the motor but the passengers will get tired of it. Limited slips can be found but they are not cheap figure $1000-$1500. I paid $1300 for H190 LSD diff in my coupe.

#6 Tom1200

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Posted 01 September 2017 - 07:55 PM

This link is a great reference for A-series motor prep.

http://www.datsunche...Rennteile75.pdf

#7 Velict

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Posted 02 September 2017 - 02:56 AM

Hooooooollllyyy... that's way more in depth than I thought it was going to be! aha. 

Thank you for that massive amount of information. I'm going to have to mull this over on what I want to do. Seeing this, I might change my mind on bringing it back to Japan. Decisions decision.....



#8 Velict

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Posted 02 September 2017 - 02:59 AM

I have to get out of the mindset of "big horsepower" considering that my last owned car was an r32 with some kick to her. 


Alright editing this: 

I've decided that it's going to be an A12 build. Just because I want to keep the originality of the truck. The question remains though, how bad is the drivability at 80HP for street? 

Also, as for the 56 transmission (4 speed which I have), is there any kit that strengthens it? such as better gears, snychros etc? 



#9 Velict

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Posted 02 September 2017 - 04:41 AM

Velict, I got your PM and will answer it as well but wanted to post up here as well because this is a frequent question for people new to A series builds.Regardless of wheter it's an A12, 14 or 15 the parts are more or less the same.

A full race A15 is going to be 150hp at the rear wheels and isn't even remotely streetable; needs 110 octane fuel and rebuilding every 6-7 hours of run time. For a full race A12 those are between 100 &110 at the wheels. These motors make no power below 5000 RPMs.

The motor in my car now would be somewhat streetable; it's a bit unhappy under 4500rpms but will at least pull away from a stop at 2500rpms, albeit not rapidly. The idle just ok and the gas mileage is poor (9 mpg on track, maybe as hig as 15-18 around town)

We're doing some fine tuning on it and I'm expecting around 110-115hp (currently 105) at the wheels which probably equates to 135-140 at the crank. Here is the spec; A15 76.5mm JE forged pistons, stock crank rods balanced, 14lb flywheel, Delta cam 278 degrees duration .420 lift, Ported GX head, 11-1 compression, SI 37mm intake & 30mm exhuast valves (SI makes them with a narrowed stem to increase port flow), 3 angle valve job, Iskederian dual valve springs, 39mm Keihin FCR Flatslide carbs on custom intake manifold, Nissan header, 210 electronic distributor set to 38 degrees at full advance (no vacuum advance) modified stock oil pump (gives 60 psi pressure) I got some smoking deals on some of the parts so I only have about $2500 in it.

The power is in the cylinder head:

You'll want the GX cylinder head, these will cost between $400 and $700 depending on what's been done to them.

Porting them isn't a huge deal, I actually did mine using a dremel. The biggest issue is the valve seat actually protrude into the port by 1mm all the way around, meaning you have a 2mm smaller port at the valve seat. Just getting rid of that makes a huge difference. Look at the pictures on Datsun1200.com of what is done around the guide / bowl area. After that match the manifold and gasket to the head. Also CC the combustion chambers so they are all the same (you can look this up) I use a piece of lexan and a basting syringe (get it in the kitchen utensils section of Walmart/Kmart etc.)

For valves use one of the Nissan prep manuals specs 38/32mm intake exhaust (as noted above you can use SI brand as the the stems are narrowed so they flow a bit more) the SI valves are 37/30. I do not remember the exact cost but I want to say they were around $150 for the set.

Delta Cams in Tacoma will do regrinds for around $100 (you'll need new lifters) as well as dual valve springs Isky sells them for a-series engines, I think they around $150

Custom JE Pistons with rings wil be around $600; you can go the Subaru Justy route for 79mm in a A15 but by the time you order up two sets have the block decked etc. it's almost as much as just buying custom pistons. Note on an A12 76mm is as large as you can go.

I prefer the Flatslide carbs but I got the deal of a lifetime $250 for the carbs and the custom intake manifold. You can price out 40-44mm DCOE carbs and compare that to having an intake fabricated and using 4 cylinder bike carbs.

For for headers / extractors you can buy the works of art Tomei ones that are a mere $3000 or generic types for $200 used. For a street car it likely won't matter. Use 2" exhaust out the back.

The one part of the equation rarely talked about are the gear ratios; the harder the motor is tuned the more it needs close ratios; a mid close box will do the job for a street car. I have both a mid close and an ultra close ratio 4 speed 56 series gearbox, these are fine for an A12 but the built A15 will eventually break them. I currently use a stock 60 series 5 speed, while I whine about the horrible rpm drop from 2nd to 3rd I recently turned my fastest laps ever with this gear box. The stock box is annoying but apparently not as bad as I thought, my motor is moderately tuned by race standards so I can get away with it.

Last is the rear end; I can't remember what is in the long wheelbase Utes, H165 or Borg Warner. If you're using a 5 speed then using a 4.11 or 4.38 ring and pinion is not a huge deal. A series motors will turn 5000 RPMs for hours on end so the lack of an overdrive won't matter to the motor but the passengers will get tired of it. Limited slips can be found but they are not cheap figure $1000-$1500. I paid $1300 for H190 LSD diff in my coupe.

I've been hitting up a bunch of Japanese shops. I've some small experience in engine building. (currently have an rb26 build on hold due to military stuff). But it's the only engine i've ever.. studied immensely. So this is all learning all over again and I appreciate your massive assistance on this. 

 

 

The closer to 150 hp the less streetable it will be. Think about it. That 150 is probably made at 9,000 RPMs on the track, so just how well will it idle and start in town? Even 100 hp would be pretty hairy. I don't suppose you would care for an L20B transplant?  

Thank you for explaining that 150 HP is pretty much overly exhaustive. I'm going to stick with 80-ish HP atw, considering you said that 100HP would be "hairy". I'll stay away from transplants at the moment. 

Sidenote: 

If anyone here hasn't really researched all inclusively for parts, here are a list of japanese websites I've found that make parts for sunnys and such. 

http://matsuoka-m.com/?cat=4
http://south-yokohama.com/
http://www.kamearien...CONTENTS-2.html

http://aobaauto.com/
http://www.pitroad-ts.com/
http://www.eeecustom.co.jp/



#10 Tom1200

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Posted 03 September 2017 - 02:13 PM

80hp atw would be streetable, I was still using pump gas at that level.

As for the gearbox; the syncros aren't the issue it's the actual gears, usually 3rd, they shred teeth. Worn bearings will exacerbate the issue. Note the gearbox is not neccesarily weak; I used a 56 series box for years without issue. Where the problems start is when you install either high output motors or the larger A15. I think I had about 8 race weekends with the A15 before 3rd went in the mid close box. I should have rebuilt it before that as the gear noise was noticeable. For a moderately built A12 in a street car I wouldn't worry about the gearbox besides make sure the bearings are good. I've read conflicting opinions on things like cryogenic treating gears, again unless it's a race car I wouldn't bother.

The gear oil is one thing that will do a box in; make sure you use GL4; either redline or sta-lube. I would not use anything that says GL4 / GL5 compatible. I inadvertently used some of the combo stuff that said it was yellow metal compatible, after the event I drained the lube and there was a faint gold sheen / flecks in the gear oil. Clearly bits of powdered syncro rings.

#11 Velict

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Posted 03 September 2017 - 10:26 PM

Yeah that's all good information. Okay, so i'll be going for an A12 build most likely. I'd like to rebuild tha 56 gearbox though. What is there for a rebuild kit / strengthened kits?

A



#12 Stoffregen Motorsports

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Posted 04 September 2017 - 08:39 AM

There is one major difference between the A12's and the A13,14,15. It's the distributor location. On the A12, the distributor is up front and the alternator is low on the driver (left) side of the vehicle. The other motors have the distributor further back allowing the alternator to be placed on the passenger side above the frame rail. Don't know if this matters to you, but it did on my 320.

 

I don't think there are any kits for these Datsun transmissions, and there definitely aren't any upgrades, but a good place to buy parts from is the Nissan dealer. They still have a surprising amount of parts available for these older cars and trucks.

 

You could also try All Transmission Parts in Portland, OR.



#13 Tom1200

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Posted 04 September 2017 - 07:53 PM

The later model A12s (A12A) had the mid distributor location and possibly the alternator moved to the high right side (passenger side for USA) location.

As for the gear box buy the good quality bearings, SKF or Nissan. For the syncros I have to look but there are two types; one type has the tangs all the way around the other has three sets of 4 spaced every 120 degrees, you want the later type. I'd have to research it a bit to find the numbers. You'll to disassemble the box before you order the parts as you need to check the clearance on the syncros. If the syncros are within spec than there's no reason to replaces them.

I don't know Utes well enough but you'll also need to see which 56 series gearbox, it's likely the later type which are stronger but none of the close ratio gear sets will fit so you have to live with the standard ratios, not that it will matter on a street car. Also I don't know if the alternate syncros are available for the later box.

As for the motor I PMd some of this; you can fit an A14 crank, use A12A rod (19mm small end) and A15 pistons (30mm pin height). The counter weights on the crank will need to be slightly skimmed so they clear the pistons. This will give you the same displacement as an A14. It's probably worth about 8-10hp, it does limit the rpm but your not likely to be revving the motor to 8600 rooms. Combine that with head work and you should get where you want to be.

Upgrade the brakes(see 1200.com for some cheap options), add some anti-sway bars, decent dampers and some 185/60-13s it will be good fun to drive. You can go with 14" or 15" if need be to keep the stock gearing but as long as you don't have long freeway jaunts I'd opt for the lower gear of the low profile 13".

#14 Stoffregen Motorsports

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Posted 05 September 2017 - 08:48 AM

Personally, I like the A12A or the A14. Best bore/stroke ratios and smooth as glass.



#15 Velict

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Posted 06 September 2017 - 05:25 AM

Awesome. I got my build planned. Going for the A12 with A14 crank and A12 bored rods to 19mm. Just looking for some good 76mm pistons. I'd rather not want to go through the sonic testing of the block for 77mm pistons. 
 

Does nissan still make the 76mm competition pistons? 



#16 Stoffregen Motorsports

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Posted 06 September 2017 - 08:28 AM

I doubt Nissan Motorsports still makes anything for these motors.

 

Does anyone here know of a reliable source of Nissan Motorsports parts?

 

Troy Ermish, Dave Rebello, Steve Epperly - I'd start with these guys.



#17 Tom1200

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Posted 07 September 2017 - 09:31 PM

I ordered my pistons from JE. I'll dig through my receipts and see if I have the order number, which you could probably use to at least get a quote. I ordered the pistons without the valve notches, more radical cams need the tops of the piston notched but I try to stick with less radical cams.

Nissan Motorsports doesn't have much for A-series motors these days.

Confirm which A12 is in your car; if it's an A12A those have a 75mm bore, I think one of the Honda motors uses pistons with a 75mm bore and 30mm pin height. That would save a few bucks on machining. If you can find the older A15 piston with the shallow center dish, that piston dish is something like 6cc, coupled 77mm stroke and the .8mm thick GX head gasket gives a compression ratio of around 9.8 to 10-1. You likely don't want more than that as you won't be able to use pump gas. Use one of the online compression ratio calculators.

Remember the power is in the cylinder head and also don't forget the power is in the head, did mention the power is in the head.

#18 Velict

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Posted 08 September 2017 - 05:41 AM

Remember the power is in the cylinder head and also don't forget the power is in the head, did mention the power is in the head.

I'll make sure to remember that and inform my wife. 

 

 

Also, I definitely know I have an original A12 (non-A) unfortunately. Just need to know where I can get forged pistons,then I'm off to a rolling start. I wonder if JE can cut 86mm pistons shallow dished to keep that 9 / 10 - ish compression ratio. Really wanting to build this right the first time, and not worry about it for 300,000KM. Just wanna be a badass A12. 



#19 Stoffregen Motorsports

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Posted 08 September 2017 - 06:19 AM

It sounds like you're in a hurry. Slow down and take your time to measure and confirm things like the cylinder head. Go ahead and cc the chambers to get an accurate number then do the engine math to figure out the target cc for the piston (whether it be positive or negative cc).

 

Tom mentioned JE as a source. There's also WIseco. Those are my two top picks.



#20 Tom1200

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Posted 08 September 2017 - 05:10 PM

If the distributor is in between is in the middle of the block (between cylinder #2 & #3) that should be an A12A, if that's the case the bore will be 75mm. I looked and its Honda D16 pistons that are 75mm bore with 30mm pin height, they have a 2-6cc dish depending on which year, so in theory those would work with an A14 crank. Me personally I wouldn't worry about the 1mm bore.

Here is what I would do; start looking for a GX cylinder head or very least a H89 head. Regardless of which A12 the car has you would be using the same head. Peter Zekert may have a GX head, he's an SCCA racer and kind of the guru of A-series race cars.

I will also reiterate go slow; when I built my A15 I ordered pistons before I took the block to the machine shop, one of the cylinders was bad enough that it was going to need to be bored out to 77mm and OOPS I ordered 76.5 mm Pistons. The machine shop ended up putting a sleeve in. That cost me $250 more than it would have if they just bored it to 77mm.