So I keep hearing people say that the chrome thickness on a turbo housing is thicker then that of a non turbo housing... but I have compared them to the best of my ability and can't see any differences... is this something that only an electron microscope will see



where does this information come from. Is it myth or fact?... and if it is fact, can someone please provide me with the facts



thanks

nope that part, the expensive hard part, is the same.

not sure what ur sayin there j9fd3s,but does that mean they are the same?(except maybe porting style from n/a to turbo)

I suspect that there is no difference at all. Thicker chrome would require that more iron be removed in the grinding operation. Also the heat transfer rate would go down as the chrome gets thicker. Just my opinion.



I could be wrong.



Lynn E. Hanover



This is a Ford powered Riley chassis at Michael Shank Racing.

interesting,would love to know if they are different for sure.

Between housings of a given series, the only difference between n/a and turbo is the diffuser in the exhaust ports on n/a housings.

And machining for water ports or not...



And knock sensors...



Minor stuff!

Have you verified that the S4 turbo housings had the casting for the knock sensor above the spark plugs? I may be wrong, but I thought the S4 knock sensor was in the center iron near the oil filler tube. Ive always heard that the S4's had the casting, but all of the cars I can remember had the sensor in the iron.

what about port timing? is the n/a port timing and port same as the turbo ones?

Knock sensors? What are those https://www.nopistons.com/forums/pub...DIR#>/wink.gif

yep. the na's have a different exhaust sleeve though

I don't know the turbo engines too well, other than that they had knock sensors.



A friend of mine does have some S4 Turbo bits lying around and there are drilled/tapped bosses above the trailing plugs, I would assume those are for knock sensors.

Like I said before, this train of thought goes against what Ive always thought about S4 turbos, but anyways... Why would mazda cast bungs and tap them for the knock sensor on rotor housings when S4 knock sensors are on the center iron by the oil filler tube? I could see in S5 and S6 where the knock sensor is actually in the housing, but I dont believe its the case with s4.

Parts commonality? It costs less to make all of the parts with a drilled/tapped boss than it does to figure out how many drilled/tapped and plain housings, then do production runs of each, twice as many part numbers to inventory, and so on.



How many rear side housings have the machined, drilled, and tapped flange for the old top mount starter, complete with casting depression in the cooling passage? If I'm remembering right, they kept that feature right up until the 13B-REW.

as far as i know, you can tell an s5+ housing form the knock sensor hole, the s4's had the knock sensor in the center iron.

ok,so how bout this.



i get 2 n/a 13b housings,put my s4 turbo sleeves in them and i have 2 turbo housings at fraction of the cost.do-able? yes or no?

yep. over here that doesnt work, cause new na and turbo housings are the same price, and used are all bad

i know where you have been mislaying the facts

housings firstly-



turbo and non turbo housings of the same year are the same, except for the exhaust port insert

( NA have the baffle )



s4 housings ( which do not have the threaded knock sensor hole )

have different leading spark plug locations to s5/s6 ones



as for the chrome-----

the s4 ONWARDS housings have a revised trochoid calculation and surface

- this is because when the 2 mm apex seals are in the "lay down" position ( trailing edge not perpendicular to surface )

they do not express the same dimensions as a 3mm seal , and the housing has been resurfaced bigger to suit

( compared to the GSL-SE and before housings )



rotors -

the TURBO s4 and s5 ROTORS have chrome plating to the apex seal SLOT, when NA ones do not

as a result the typical apex seal when installed is fractionally tighter fit

TURBO side seals are also moly disulphide coated, NA ones not





PS

i have used earlier 3mm rotors quite successfully in late housings, despite very small trochoid differences

i have used NA housings sans the insert AOK on turbo motors

i have successfully used 9.4 2mm ( s4 NA ) and 9.4 3mm ( GSL-SE ) rotors no problem in s4/ s5 turbo hybrids

i have not payed much attention to finding moly side seals either, both perform fine

I have laid Series 4 rotor housings dowel to dowel on early housings and I couldn't detect any place where the dimensions were different. A straightedge laid across the surface laid flat against both housings at all points.

while i have seen it myself, and also read it across many sources

- i suggest you read page 3, article B

even cerment agree

the housings change trochoid , especially when it went from 6 mm to 3mm and from 3mm to 2mm apex seals

http://jhbperformance.com/downloads/jhb-te...performance.pdf

Perhaps then I had the rare 3mm seal FC rotor housings, or the 2mm seal 12A housings. (Not likely!)



It is good to actually measure things and experiment instead of playing librarian and repeating what everyone else says.



For instance, there was a diagram in the late 60's put out by Ford detailing the upgrades made to their small block when they bumped the displacement up from 289ci to 302ci. (1/8" more stroke, biiig deal) On the graph was a notation that the cylinders were made deeper to accomodate the stroke. This may have been something the engineers intended to do, but somewhere in the lead time between making the graph and actual production of engines, that dimension ended up NOT changing. So you get a lot of people regurgitating that the 302 has a longer cylinder wall, you can't put 302 cranks in 289 blocks or all manner of bad things will result, and so on. And the people who bother to sit two blocks next to each other and measure find out that it's been the same thing all along, and the diagram was in error...





Do not also forget that for the FC engines, the turbo rotor housings are drilled for coolant flow to the intake manifold and the non turbo engines are not. This needs to be dealt with if cross-pollinating.

LOL

is black blue?



i can aslo recall seeing the mazda article showing the changes to the trochoid

so your calling mazda and cerment liars??? could it be that your wrong??



have you seen the very slight housing contact that 13B 3mm rotors make near the combustion zone under boost in 13Bt housings ?



i have

i have also lay-ed the two different housings on same dowels and i could see the difference with naked eye



the rotors will swap, and run OK, but not optimum OEM sealing pressures or angles





thanks for your misinformation



take it or leave it,, at least i provided some backup for my statements

( thanks cerment , though apparently you don't know how to measure a housing, and should get out your straight edge ????!! )

i have done the swaps, and noted the results

i failed to take photos of this sort of crap because--

gee- pre digital camera days , and mazda state it plainly