Roy James

While im rebuilding this 4 port block that had N/A rotors in them i kinda just wanna know what series these rotors are. Is there any identification numbers on the rotor itself? If so where is a identification chart at i can look at to tell the differnce?

Thanks

mazdaspeed7

You can tell the series, but i dontknow about the compression ratio. The bathtub shaped indention on the face of the rotor is machined in S5 and later, and as cast in S4 and earlier.

www.mazdatrix.com has some info on identifying rotors, I believe.

hypntyz7

Experience helps a lot, but here is a good way to tell:

if the surface of the rotor faces is smooth, they are s4 rotors. IF the surface has lines in it, they are s5. IF you have a really accurate scale, you can also weigh them s4s are heavier than s5's.

IF you put a turbo rotor beside an NA rotor, the difference is pretty obvious. BUt, just for an untrained eye to look at one, it iwll be hard to tell. THe turbo rotors have a much deeper dish than NA rotors. IF in doubt, use a measuring tape to check the depth of the "bathtub" mentioned above. YOull have to post back here what you find out, as I dont remember the depths off my head, but I have plenty of rotors I can measure downstairs,.

Roy James

cool man, ill go check that in a lil while after im done eating, its an S5, but i cant tell turbo or not. Im almost 100% positive its an N/A bc it pulled pretty good, but.. you never know. I just want to know for sure, not just by "butt dyno". Thanks man

Roy James

I rough messured the dip as well as i could and it was roughly .5". It is an S5 bc i took an S4 N/A rotor i had laying around and the S5 had the machining marks. I think it is a TII S5 rotor bc i compaired it to the S4 N/A and it seemed a lil deeper, but **** if i can really tell. Thanks guys

Roy James

bump. Any word on that messurement Kevin?

hypntyz7

s4 t2...1/2" 8.5 comp.
s4 NA 3/8" 9.4 comp.
s5 NA 11/32" 9.7 comp.
s5 t2 ??(less than 1/2" but more than 3/8") 9.0 comp

s5's will have machine lines on the faces, and s4's will not. The bathtub of an s5 will be smooth with machined lines, and the bathtub of an s4 will be rougher with pits.

Roy James

Cool, Thanks man!, im going to go get a more accurate messurement, if what you say is correct, and my messurement is correct, then this TII motor has S5 N/A rotors..... No good for turbocharging. --POP!---.. unless you think it will make more power with the N/A rotors if its tuned VERY CAREFULLY with a wideband (i have one on the way).

hypntyz7

Frankly Im pretty ******* confused about the whole deal. You first said it was a t2 block with NA rotors, then you said you thought they were s5 t2 rotors, then s4...or wait, was it...??

Best to take some detailed pics I guess. What youre talking about doesnt make any sense...what did you start with, and what are you trying to do?

Roy James

LoL, sorry about that man. Well, here is the spill on this block. I got it from a freind that pulled it out of the J yard and slaped it in his 87 base. The block, from the J yard, was a TII block with an N/A intake on it, (the lower intake manifold was bored out to hell and back and had an adaptor plate so it can be used for the TII block) and was fast as ****, just had a coolant seal blown. I suspected a ported/built TII block with N/A rotors. After what you and Adam have told me, i have come to the conclustion that they are S5 rotors and more than likley (due to the power of this thing) are N/A for sure. I dont think anyone would want to run TII rotors for N/A... thats just stupid. I want to rebuild this motor and turbo charge it for my 86 Base. I was just going to turbo an N/A block that i have on the way, but, i think this one will give me more power and flow better. I asked you, in my last post, if you think the S5 N/A rotors will be "OK" to turbo if tuned VERY CAREFULLY with a wideband. Like, do you think the power increase per PSI/CFM is going to be worth it? Thanks and sorry so confussing.

hypntyz7

Ok, that makes a bit more sense. Someone built this engine to be a 4 port NA. simple as that. the turbo terminology threw me off. You use turbo end and int. plates for larger ports.

So, put it back just like it was. Screw a turbo...you could never get that to work right. Think about it dude...how many years adn millions of dollars do you think mazda spent engineering the t2 in stock form? They set the car up to last for years under a variety of conditions, This means they allowed a lot of room between what the car *could* do, and what they set it up to run.

Now, think about how many stock or lightly modded t2's you see blown up. Why is that? These were set up as low compression, rich running engines from the factory? All it takes is a hot day or poor fuel to do away with all those safeguards.

Now imagine doubling your chances of failure. That's what youre talking about doing. Going from 8.5:1 comp. with stock tuned EFI programmed to run rich(stock turbo setup that is on the edge all the time) to 9.7:1 comp with a modified/hacked control system. What are you trying to do? lol

Roy James

eh, just thought i would ask. Thanks for your honest answer. Well.. you wanna sell me some TII rotors?

hypntyz7

Just put it back like it was...it'll be cheaper and if you port it out a lot and do basic IHE mods it will run like a stock turbo II with better mileage and mor reliability. Trust me on this one. You do not want to try adn do a turbo conversion on the cheap. I prefer a tuned NA engine anyway. No ****. Im trading my t2 for an NA.

Roy James

Man, you are nuts. Speaking of nuts.. LoL. you are going to laugh at my stupid *** so much right now. I went out there AGAIN, just now.. and looked at it. I looked at the dishes (the combustion chamber dishes) and both the S4N/A and the "mystery rotor" have the same lil crater type marks in them.. putting them side by side, the "mystery" is way ******* deeper... its a damn S4 TII rotor... what.. THE HELL IS GOING ON HERE! When i saw "machineing marks" i saw them on the sides of the rotors, the lil small dime sized dishes on the sides that looked more machined on the "mystery" rotor and the S4N/A rotor i already had. Man oh man someone help me. How in the hell is a TII block with N/A intake fast? I messured the two, the "mystery rotor" was a hair under .5 (i got a good clean accurate ruler this time) and the S4 N/A i had was right at 3/8 like you said.