2nd gen Engine/Drivetrain Engine/Drivetrain Modification Discussions for 1995-1998 Models Only (BH chassis)

Head swap on the Z5 engine

Old May-16th-2004, 01:07 PM
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Head swap on the Z5 engine

So, The Z5 has the exact same bottom end as the B6, so why not a B6T head, intake manifold and exhaust manifold (Turbo etc) swap?

The intake manifold would sit too high for the stock hood, but it could be modified, or the Z5 one could be port matched to fit.

This would eliminate the mounting and wiring issues of the BPT to 2nd gen swap.

Just some thoughts.
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Old August-9th-2004, 03:42 PM
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Whoever told you that is incorrect.

The z5 and B6 have only the following things in common.

They are Mazda engines

Both are DOHC 16 valve four cylinder engines.

They can be found in the second gen protege (however the B6 was not available for the second gen in the North American Market)

They have almost the same displacement.

Sorry, you're out of luck.
The only hope is an engine swap or turbo. I believe there was a variable valve timing version available in Japan or somewhere overseas though I could be wrong. I might be thinknig of the ZL-VE.

Aside from that, you're going to have to go turbo. Essential Speed is currently developing a turbo kit or perhaps they have already developed it, I'm not too sure.
They also have Headers an intake and Catback available for your car. Don't really expect much from the I/H/E though. I'd guess that you would be lucky to get 15hp.
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Old August-13th-2004, 09:40 PM
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According to RandyS of www.solomiata.com (who really knows his stuff), the Z5 and B6 share the same short block.

He may be wrong, but he's correct about a good many things, so I'm inclined to believe him.

The 'Z' engines are a new family which is an evoltion of the 'B' engine. The head is entirely different with round ports and narrow valve angles but the shortblock is nearly the same as the B6
This is from this page, on his website. If you haven't read it, it details out almost all of Mazda's 4 cylinders.

http://members.aol.com/solomiata/MX5Engine.html
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Old August-14th-2004, 10:02 AM
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Matter of fact I have read that article, several times. I guess I overlooked that part, or just didn't bother paying attention to it.
Thanks for setting me straight, This does open up some possibilities.
I think a good way to figure out if they would interchange is to get a head gasket from a B6 and a z5 and compare the sizes of the bore, water jackets, oil passages, and head bolt holes etc..............
Manifold gaskets would be useful too for comparison.
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Old August-14th-2004, 12:17 PM
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I think the ideal setup would be the Z5 intake manifold, mated to the B6 head, with the B6T exhaust manifold and turbo.

Timing belt length may be different due to the different head designs.

I think the only real difference between the bottom end of the two engines is compression ratio. Does anyone know the Z5 C/R?
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Old August-14th-2004, 03:46 PM
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Originally Posted by FlySwat
I think the ideal setup would be the Z5 intake manifold, mated to the B6 head, with the B6T exhaust manifold and turbo.

Timing belt length may be different due to the different head designs.

I think the only real difference between the bottom end of the two engines is compression ratio. Does anyone know the Z5 C/R?
I think the real ideal setup would be a custom intake manny if the B6 manny is too tall, its difficult to say wether or not the z5 piece would work or not. The compression ratio of the z5 is 9.4:1

The compression ratio of the B6-E is 9.3:1 however that is the SOHC 8 valve engine not the DOHC B6 used for the B6-T. THe z5 has a timing belt which runs a single cam gear. The other camshaft (not sure which one is driven and whih is drive) is run from another gear attached to the belt driven gear by a chain, so a B6 timing belt might have to be used. I'm not sure how the compression ratio of the z5 bottom end would be affected by the head swap if it does work, but it should be somewhat easy to figure out if you can find out the CC volume on the B6 head and the BDC and TDC volumes of the z5 block as well as the approximate thickness of a crushed head gasket though I'm not sure which could be used z5 or b6.
If you want to do this, I'm quite interested to see the results if such a swap is possible.
Keep me informed since if it works it opens up HUGE possibilities for the z5 since as of now there is little to nothing for the z5 as far as cams and other engine parts go.
Right now there are really only a set of headers a catback and CAI for it. A turbo kit however, is under development for the Z% but I don't know if it is completed yet.
I'm not a Mazda guru by any stretch butI'd be happy to offer advice wherever I can.
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Old August-15th-2004, 12:47 AM
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Well, my protege is my wifes daily driver, but I noticed you can get a low milage Z5 off ebay for $350. I might just buy one to tear it down, and attempt the head/manifold swap.

I'll keep you posted. If someone wants to help provide a DOHC B6 head for me I'd be very happy.
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Old September-11th-2004, 12:51 AM
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Well you should talk to Edwin about the question of the same block. If anyone was to know if they were the same, most likely it would be him.
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Old May-4th-2005, 06:25 AM
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i would like to say that by trying it myself, the B6 head will indead bolt onto the Z5 block. they carry the same head gaskets as the bolt holes, oil passages and the water passages all align perfectly. the difference in the sort blocks is that the B6 block is much stronger, with fatter crank and rods. and yes the timing belt from the B6 would have to be used cause it is longer since it has to go over 2 cam gears instead of one. neither the exhaust or the intake manifold from the Z5 can be used. they will not match back. however the throttle body and throttle sensors will bolt onso that the ECU can be retained.
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Old May-5th-2005, 01:03 AM
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That's awesome stuff! How much power capability are we talking about if this were to work out? I would also assume a clutch and tranny upgrade, but how would you upgrade the trans? Replace it with different and stronger one altogether or what? Or could it take the power increase? Sorry about all the questions, but I just want to know. Oh, that would be a trip trying to fit the turbo in the 2nd gen's engine bay...these cars would be sleepers though (well, not huge ones, but you get the picture). Thanks for the heads up guys.
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Old May-6th-2005, 07:01 AM
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The truth is that i have not dynoed the setup. but by feel of the pants, i is a great improvement. there is only one tranny upgrade that i have heard about and that is to change from the F25M-R tranny to the G25M-R which is suppose to be much stronger and there is an lsd for it. the stock lsd for the mazdaspeed protege is suppose to fit right back in.
As for a turbo setup, even more potential can be seen from this setup, but you have to remember to pay close attention to the cam timing as the overlap for the N/A setup is different from a Turbo application and you should use camgears to adjust the cam timing, or alternatively you can retard the exhaust cam by one tooth which would decrease the overlap.
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Old May-6th-2005, 07:48 PM
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Originally Posted by Twincam16
i would like to say that by trying it myself, the B6 head will indead bolt onto the Z5 block. they carry the same head gaskets as the bolt holes, oil passages and the water passages all align perfectly. the difference in the sort blocks is that the B6 block is much stronger, with fatter crank and rods. and yes the timing belt from the B6 would have to be used cause it is longer since it has to go over 2 cam gears instead of one. neither the exhaust or the intake manifold from the Z5 can be used. they will not match back. however the throttle body and throttle sensors will bolt onso that the ECU can be retained.
Details.
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Old May-6th-2005, 09:53 PM
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Originally Posted by Twincam16
The truth is that i have not dynoed the setup. but by feel of the pants, i is a great improvement. there is only one tranny upgrade that i have heard about and that is to change from the F25M-R tranny to the G25M-R which is suppose to be much stronger and there is an lsd for it. the stock lsd for the mazdaspeed protege is suppose to fit right back in.
As for a turbo setup, even more potential can be seen from this setup, but you have to remember to pay close attention to the cam timing as the overlap for the N/A setup is different from a Turbo application and you should use camgears to adjust the cam timing, or alternatively you can retard the exhaust cam by one tooth which would decrease the overlap.
So the difference between the F25M-R and the G25M-R is just generations or what necessarily? And G25M-R bolts straight on to the Z5 block? That would be nice. I would also assume switching out to better half shafts would be in order as well...just to cover the bases.
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Old May-7th-2005, 06:25 AM
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for the gearbox question, check out this FAQ website, it gives you generation of the different gearboxes and also things like its gear ratios and cars it came on
http://web2.airmail.net/theman/protegefaq/
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Old May-7th-2005, 08:59 PM
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Thanks
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