what can I take from BP-4W?

[russian239]

also given the popularity of Miatas and BG-chassis **** in LeMons, I wouldn't put money on those nerds not noticing a difference between a BP05 and BP4W head. it's not some redneck circle track ****...

Yes, not redneck. Still, look what they call my B3 > BP swap: http://blog.caranddriver.com/lemons-...y-two-seconds/

[FE3-323]

pull the whole motor & be done with it.

[russian239]

I have removed the head & hidden it at the yard - my plan is to buy it 50% off during the sale next weekend.

Funny thing - there were three BP engines in the yard (this miata, older miata and an escort gt). On all three the valve covers are gone. Who the heck would need so many valve covers? I know both miatas were added to the yard THIS week.

Anyway, on top of the intake mounting another difference is the coolant inlet - on the miata head it's on the head, between the cam gears.
What is the plan? Which inlet should I use and which inlet should I plug? What about the coolant passages inside the head and between the head and the block - is this going to work at all? I guess I should check if head gasket is the same but something tells me it is not.

I will go PM ftjandra

[ftjandra]

Plug the hole on the front of the Miata head with a freeze plug (30mm iirc). This makes the front identical to a Protege head.

The rear (Miata orientation) of the head is also slightly different. The Protege head has a pressed in fitting that consists of two nipples - a large one for the heater core feed and a small one for the oil cooler feed. The Miata head only has the smaller one. Easiest way to get the heater core feed back is to use a spacer between the head and thermostat housing with a barb for the heater core (pre-thermostat).

Use the Protege head gasket.

--Ferdi

[russian239]

Plug the hole on the front of the Miata head
...
Easiest way to get the heater core feed back is to use a spacer between the head and thermostat housing with a barb for the heater core (pre-thermostat).

Thanks a lot for the prompt response!

We are already running without heater - the hose is just looped instead (that's a race car and this way it saves us a minute on each engine swap). I guess we will simply shut the heater line down, I guess that's the same as running with heater turned off?

[ftjandra]

Water is always flowing through the heater core whether the heater is on or off. There is no bypass valve like on some other cars.

A small amount of coolant needs to bypass the t-stat for everything to function correctly (I forget the actual reason). If you are blocking off the heater core hoses completely, I'd drill a small hole (~3/16") in the t-stat to act as the bypass. That's what we did on our race car.

I bet your race car takes forever to warm up with the lines looped.

--Ferdi

[russian239]

If you are blocking off the heater core hoses completely, I'd drill a small hole (~3/16") in the t-stat to act as the bypass. That's what we did on our race car.

Actually, there is no t-stat inside the housing. So far this has worked for us (24 + 14 racing hours on current engine)

[ftjandra]

Does your engine ever get up to temp? Especially where it's cold like in Chicago?

--Ferdi

[russian239]

Does your engine ever get up to temp? Especially where it's cold like in Chicago?

It was maybe 60F/15C outside during our last race and the engine was about 130F/55C while racing and 170F/75C while driving in the paddock. Not super sure about these numbers but that's my recollection.

[ftjandra]

That's not really optimal for wear or anything. Ideally you'd want to be at least 180°F. You'd get better mileage too as it would be running super rich at those low temps.

--Ferdi

[russian239]

That's not really optimal for wear or anything. Ideally you'd want to be at least 180°F. You'd get better mileage too as it would be running super rich at those low temps.

Super-rich and bad mileage actually ring a bell! Maybe that's why we are running rich (because we do)! Thanks for this hint, too. I guess we should re-evaluate the t-stat approach and actually put one in and drill a hole in it.

[Kitty]

Funny thing - there were three BP engines in the yard (this miata, older miata and an escort gt). On all three the valve covers are gone. Who the heck would need so many valve covers? I know both miatas were added to the yard THIS week.

People that powder coat gank valve covers and a few other parts desirable parts quite often to sell directly or decrease the return time to the end customers if they have a specific demographic.

[Chrisgtx]

I've got a bp4w head,and I'm still undecided on if or how to get it ported,I believe there is an optimal valve seat angle,which I can't remember at the moment,or what cams to run with it,or,just port match it and leave it stock?

[FE3-323]

15/45/70

[russian239]

Work is still in progress but here are some pics:







I think what Jim did here is just beautiful.