What is the highest PSI you know of that someone boosted a N/A motor with the stock N/A rotors without blowing something up? I mean someone you would consider reputable, or something you have seen yourself, not just someone talking Shiznit.

 

12A Turbo - 29lbs.
10.19 @132mph.

Street legal.

 

Did it have stock N/A rotors, or is this the J-Spec 12A turbo I?

 

You asked for stock NA Rotors, I gave you stock NA rotors.

The 12A's for some reason really, really, really like high boost. High compression rotors and all.

The old sayings about only 6lbs of boost on high compressions rotors is old school.

As long as there is enough fuel and spark at the right time (well tuned), a good intercooler system to keep the charge air temps down, with a well matched component system - Even more boost is possible. In Puerto Rico, guys run 45+ lbs of boost on high compression 12A's and 13B's.

 

Cool, I just wasn't sure if you were refering to the 12AT. I have some 13B rotors that are good. I want to boost the engine, but I wasn't sure if it would be safe with stock N/A rotors. I also heard that 6psi was the limit. I'm thinking more and more that I'll use the N/A rotors since nobody in the for sale section has wanted to buy them.

 

this is key!!! and just to add to what Directfreak said, another thing to consider is that during your build-up, you can alter the way the engine deals with the boost with the size and shapes of the ports.

 

Yeah, and keeping the boosted air temp down. I was seriously considering using a supercharger, but It would be more difficult to use an intercooler with a SC. But turbos need that computer controlled if you want to boost really high and stay safe. I may just have to go turbo if I keep the stock rotors.

Thanks for the input guys

 

well, given the choice between turbocharger and supercharger ... i must admit that i'll take turbo everytime! and yes, a good management system would be in order to take "some" of the guess work out of your tuning issues, but if you're still open to both ideas at this point, then just see how much more info you can gather on supercharging from sources in the know (by the way ... that would probably be anyone but me )

 

Two more things to keep it simple (carbed and ECU less)

1) Locked distributor, with timing locked for boost

2) MSD6BTM

 

Damn I'm part of the old school, I thought it could only put down 6-7 psi.....hmm project turbo might be revived. Time to read up on carbed turbo applications again.....Turbo SA

 

Only 6#'s? Sheesh.... If that was the case why would you even bother!

And yes a turbo SA is definately my next order of bizness!

 

Atkins rotary said that 6psi with the camden supercharger will increase hp by 30%

 

That's exactly why Project 12A Turbo was put on the shelf. I thought the only way it would ever be turbo would be a T2 swap.

 

if running BIG boost is that much of an issue, why don't you just have your 12A rotors machined by someone that knows what they're doing? i mean, you'd have to have them modded anyway if you're going to do it right, so why not just have them machined for lower compression while they're out and away?

 

That's not as easy as it sounds, then you need the correct counterweight, and have the rotating assembly balanced.

By the way guys,

You CAN easily blow your engine with 6 lbs of boost too.
Again, you need to understand, extra fuel, correct timing, and cold charge air are BIG factors in the equation.

 

As for fuel... How much psi should I run in the fuel system?

 

Get a Malpassi Rising Rate Fuel Pressure Regulator,
It will go up 1:1 with every pound of boost.

So basically, you tune the fuel pressure to work as an NA application, and the fuel pressure will work under boost with the right RRFPR.

EDIT:

Guys, a well done (and simple) 12A Turbo setup was already done by MoreMazda. He did a nice write-up HERE on how he did is 12A Turbo, with pics and everything.

 

well, naturally ... i guess i should have stated that as well. thanks for picking up the slack and mentioning those details ...

and yes, Directfreak is absolutely right. you can blow up a motor running 6 psi. fuel and ignition are critical to any motor's health, but they become that much more key when you're running an application with positive manifold pressure. so i guess the point i'm trying to make ... which is basically just my chiming in on what he has already stated, is that low compression is not going to save you from poor tuning. so you can use what you have, just make sure it's well planned and then done right.

 

It seems reasonable that the 12A could have a higher threshold for detonation because it is 10mm narrower. Of course high boost can be made to work on any engine compression if the fuel is the right amount, has a high enough performance number (octane), the right conditions of timing, temp, etc.

 

Also, 9.0:1 isn't really that low if you look at piston high boost applications, I've heard as low as 6.5:1, so 9.4:1 oh 1st gens isn't that much more than 9.0:1 and shouldn't make that much of a difference (all other things being equal)

 

Another thing I noticed is that the difference between N/A and turbo rotor copression is not that.

76-85 12A 9.44
74-78 13B 9.25
84-85 13B 9.45
86-88 13B N/T 9.44
86-88 13BTII 8.54
89-92 13BN/T 9.74
89-92 13BTII 9.04
93-95 13BT/T 9.04

 

people boost S4 N/A rotors because theyre stronger than the lighter S5 N/A rotors and from being stronger they can take more boost.
I have no idea how 12a rotors are though.