Experience with 323 GT-R head?
 

Anyone some experience with a 323 GT-R head in the 1.8 miata?
As far as i know this thing got bigger valves, better head geometry, modifyed in and outlet channel, better hydraulic valve lifters etc....

i need a new one and a tuning company offered my this head completly rebuild and modifyed.

But i am not sure if its worth or not!?

As far as I know, it should just be a worked 94-97 spec head.

BPD

The mazda BPD engine (also commonly referred to as a BP2) was a revamp of the original BP engine (sometimes called BP1 for clarity's sake). It featured a larger crank nose, larger piston oil squirters, a main bearing support plate, better flowing inlet and exhaust ports. This was also the base engine for the Mazda Familia GT-R and GT-Ae. It is commonly known as the 'big turbo' variant as it utilised a much larger IHI RHF6CB watercooled turbocharger(vj23). The BPD was used as the basis for the engine, with changes such as sodium filled exhaust valves, larger (and front-mounted) intercooler, larger (440 cc) low impedance fuel injectors and stronger engine internals helping to up the performance of the engine to produce 209 hp (156 kW) and 184 lb·ft (255 N·m). The VICS system of the N/A BP has been removed, as well as the boost cut from the ecu. This engine was designed to power Mazda to a world rally championship win, and was thus used in the limited production Mazda Familia GT-R (2,200 built) and GTAe (300 built).

If they have over sized the valves then it will probably not be sodium filled valves...which from my understanding was to increase the life under high heat and stress while being slightly lighter.

The intake manifold was different to the standard BPT as it had a smaller plenum with long runners. From memory the head still has the turbulence tags to improve atomization for improved low end torque. The valves were the main highlight of that head.

Most of the GTR / GTaE improvements were in the bottom end, turbo and gearbox with shot peening and additional webbing on the cast items.

Hope it helps.

for me the most important question, is this cylinder head a major improvement compare to the stock one and is it wort to spend around 1500€!

i want to build the engine setup for a 300+ bhp engine. I already GT-R pistons and K1 rods and i need a new cylinder head anyway, the old one is broken. but if the GT-R head only make sense at a minimum of 400bhp, then i get with the stock one.

hope you understand what i mean!?

and thx for all the helpfull answers by now!

The stock head will EASILY make your power goals. :)

I wouldn't spend 1500 pounds or whatever that is for a BPD head.

For 1500€ that better include some fancy fucking porting and a blowjob too!

not worth that much!
better to buy an NA head mild port with new cams IMO.

Sounds like the shop essentially removed everything that makes the head desirable. The intake ports have a restriction to try and help low end torque. I doubt it will be the limiting factor on horsepower under 400hp though, overseas people seem to make good power on stock bpd heads. The sodium filled valves are the real gems in the head. I take it the head has the turbo bp26 cams?

For that kind of money I think I would rather just have a stock casting head built up, hopefully for less money.

For the money it sounds like you could get a 99-00 head and do some work on it. That's what i'd do.

yes, it is expensive, but the head is complette with special cams, valves etc. and got all the ports modifyed with a cnc maschine...

But thx for the feedback, i guess i will leave it and go with a stock one.

A head could easily be worth 1500 if it has custom cams, port work, etc. But like others have eluded to, it is not really necessary for what you are doing.

I would love to know what that cylinder head flows. Is there any chance the seller has that information? It would certainly help in determining if it is a good deal or not.

For your goals it is not worth it.

due to the lack of available heads, i guess this would be easy but most of the heads are alaready quite old and the cam bearing are out of tolerance, i go and get the modifyed one. maybe it is expensive, but it works.... hopefully.

The tuner told me the head brings the same bhp at 0,1bar less boost and even have lower exhaust temps.

We will see....

i guess there are no flow charts available. currently the head is at the mashine shop and get the ports modifyed. as soon as i get it, i make some detail pictures from everything if you are interessted....