I'm assuming the internal parts are free and you can up the compression to 12-1 or beyond. With the other mods you're allowed I'd say 85HP tops but likely closer to 80. The stock carb is very small, the key will be matching everything, not going crazy with valve sizes (assuming you can change them) and matching the cam.

Tom

Back when I was helping wrench on an SCCA ITC 1200 it dynoed out at 74 hp at the rear wheels. The only mods were a 32/36 Weber, porting for an inch on either side of the head/manifold surface and a header.

Grover since I didn't specify my guess was 80-85 at the flywheel. I was trying to remember what the guys at Nissan Comp got out of their ITC car. 74RWHP for an ITC car is very good, with moderately ported GX head GX cam and 39mm FCR flatslide carbs I got 73HP at the wheels..................and I was really happy with that.

Tom

PS what Region did car run..............Cal Club had 3, Red and White one pictured in the catalog a Green one and a Blue one, they would occasionally run at LV Regionals. Also there was an immaculate orange GT-5 car with the best flares I've ever seen, coke bottle shape and they were blended in perfectly...........most GT-5 1200's full flares were obviously added on.

Tom, This was in the San Diego Region back in the late 80's-early 90's. The car was number 56/red. The owner and engine builder was Jack Tietjen who was the head of Tech for SD for a number of years. Our best year was 11 class wins in 12 races in the SD winter series.

If you wanna unload a hug wad of cash, (And your class rules permit) get some custom super lightweight pistons, and Aluminum conrods. Knife edge your crank, and get some aftermarket rocker arms. (with a higher ratio) I'm gonna guess that if you aint allowed to change your carbs and header, all the other goodies will be taboo too?
Get some lightweight titanium vlaves. Buy some tomei lightweight valve retainers. Then you might get up around 110 with the right cam, and everything else right too. Perhaps hunt out a gx cast iron header.

I have a feeling Junior Sedan probably has some strict engine regs, if they ban extractors. So it probably has to be the original engine, maybe with an overbore limit, cam restrictions,etc. Must look up the category regs. Basically, get everything square & parallel, the line bore for the crank straight, the piston bores at right angles to the crank, the conrods straight & the pistons square, the combustion chambers equal, no drag from the bearings. Basically what is called Blueprinting an engine.

All this means you might get 90-95 HP from the motor, or maybe a bit more, but the engine should be a bit more willing to rev. Do you have a web site we can look at to check engine regs? Have you emailed or PM'ed Ernie (BigE) here in Sydney? He does speedway engines & probably knows the engine regs for Junior Speedway already. Ernie might be able to point you in the direction of an engine builder in WA who can help with the engine.
AS for the most HP I heard of out of an A12, I've heard of 1300 cc A12's making about 130 hp at the crank, with a cam life of about 30 minutes. Thats right, I haven't seen this for my self, but the person telling me about it was someone I've had do work for me over 20 years & I trust him. Note that this was in a Formula 3 race car when they had 1300 cc push rod engines back in the 70s-80's & the camshaft was thrown away after 30 minutes running, basically one race meeting. Somebody in Melbourne was all he could recall about who.

My 1298cc A12 I had in my 1000 hillclimb car made probably about 105 HP at the crank, never got it measured, but it was enough to do high nine second eighth mile times, with revs about 8500. Lasted over 2 years in the 1000 before it was sold to a rally driver who ran it for a few years winning his class in PRC 0-1400 in a 1200 sedan. The driver told me he always changed up at 7000 rpm because he knew all sorts of fun was just about to occur if he revved it further. That engine had a speedway grind cam it in, with plenty of low down torque & lots of lovely horsepower.

Aww man, all this talk recently about A12 power has got me wanting to build one and compare it to my A14. Was pretty chuffed that I am making just under 95hp at the wheels with it running lean as, like 14+ :o

But yeah I'd love to get one of those A12 blocks to rev past 8k

I was revving my A12 to 8600 pretty regular...............they start to where out quickly with that kind of treatment.

Peter Zekert has said his full race A12's are right at 100 HP at the wheels, the engines are gone through pretty often. Think 6-8 hours. Another US racer Dave Patten's A15 (without the restrictor) managed 156hP at the wheels..................14-1 one compression, Revved to 9K and all sorts of other goodies..............nowhere near streetable.

Grover I started with the SCCA in early 1989, new lots of SD Region folk, mostly corner workers. The old 200SX emergency car we used was donated by San Diego Region.

Junior Sedan sorry for Hijacking the thread.........

Tom

If it's anything like ministock racing here, you aren't allowed to do bugger all to the motor. I once browsed the ministock rules, and to get an edge, you'd really need to build the engine clever. (I can think of a few small things that could be done)Downsize the rocker shaft a little bit, and fit offset bushes to the rocker arms to gain a little extra lift. (and if they ask to check your lift, remove the rocker shaft, so they can measure it at the push rod) Can you run flat tops? If not skim a few thou off the crowns, (To widen the squish bands on the pistons a bit) and then zero deck the block. Back cut the valves. Since you're gonna be stuck with a small cam, get that bit more flow at low/mid lift. Plus the valves only see peak lift once, but they see the mid/low lift twice during an intake cycle. is painting/polishing/coating the engine internals allowed? Coat the crank and rods with the oil shedding film to cut down on windage losses. use a lower profile lock nut on the tappet adjustor. That tiny bit less weight means the valve train can accelerate just a wee bit quicker. Make some lighter weight valve reatiners. Probably not legal, but done right it'd be hard to pick.
Since you're hamstrung by the rules, you have to do lots of little things to gain just the slightest edge. I wonder it you could use ring spacers, and run super thin rings for less drag on the bore wall?

in reference to question of thread,
the people who are most likely to try and extract the most hp from their NA race a12 1300cc would probably be from japan,have deep pockets and also access to very high quality parts that were developed just for racing.i.e nismo,tomei parts etc etc.Chances are they are not on forums to answer this type of question.i.e japs 1200 tomei owner.and if they are,they will be on japanese forum.Most hp from an a12 will mostly depend on how much your willing to spend.

that said, japan 1300cc ts cup a12 engines claim 170ps.this is what i refer to as "worked" a12s !!!