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-   -   my n/a supercharging project complete (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-n-supercharging-project-complete-289791/)

Bauer778 04-09-04 11:02 AM

I have a question about the idler pully, is the purpose of this just to adjust to tension of the belt or does it have another function?

Thanks
Dan

wozzoom 04-09-04 11:07 AM


Originally posted by Bauer778
I have a question about the idler pully, is the purpose of this just to adjust to tension of the belt or does it have another function?

Thanks
Dan

Correct. A Supercharger blower takes a lot of HP to turn. The idler pully keeps high tension on the belt so it doesn't slip.

For example, the Eaton M90 blower that zBrown installed requires ~50 HP to turn the unit to 14,000 RPM @ 10 PSI. (40 HP @ 5 PSI) Without proper tension, you'd melt the drive belt.

This is why I can't believe that zBrown's v-belt isn't slipping at higher RPMs.

Bauer778 04-09-04 11:14 AM

Thanks wozzoom

Is there a way that you can convert the belts to serpintine ones ?

Chimeron 04-09-04 11:19 AM

CAS = crank angle sensor. And as far as the 14k rpms, he said it's only seeing up to about 11k, but still close so you have a point.

wozzoom 04-09-04 11:22 AM

This is going to be the trick... I don't think we need to convert the entire engine to one serpentine belt but it would make things easier. Atkins Rotary has a kit that supposedly converts a 13B to serpentine belts, but there are no pictures of it on there website. 3rd gens also has a serpentine belt.

From the pictures that zBrown posted, it looks like he used the stock Power Steering pulley to drive his SC. (He has no power steering now) It should be possible to remove the stock power steering pulley and replace it with a 6-8 ribbed serpentine belt pulley.

wozzoom 04-09-04 11:24 AM


Originally posted by Chimeron
CAS = crank angle sensor. And as far as the 14k rpms, he said it's only seeing up to about 11k, but still close so you have a point.
http://www.magnusonproducts.com/images/mp90g2.jpg

We're still looking at 25 HP to drive the M90 to 11,000 RPM.

Bauer778 04-09-04 11:30 AM

If it takes 25 hp tp drive the Sc how much power are you actually getting out of it? For example when they say that the get 40 hp out of it , is that 40 hp on top of the 25hp, or is that 40hp and the minus the 25 hp to get the thing to run, so your net gain would only be 15 hp?

wozzoom 04-09-04 12:38 PM


Originally posted by Bauer778
If it takes 25 hp tp drive the Sc how much power are you actually getting out of it? For example when they say that the get 40 hp out of it , is that 40 hp on top of the 25hp, or is that 40hp and the minus the 25 hp to get the thing to run, so your net gain would only be 15 hp?
The HP gain is measured at the rear wheels. so using your numbers, the increase in engine HP would be 65 HP.

fg0d 04-09-04 01:13 PM

25hp lose compared to the gains is still worth it.

Would it be possible to hook the m90 to a TII?

It has to be feasible. A sc'd turbo :)

One drives the pulleys, one uses the exhaust gases.

SonicRaT 04-09-04 02:06 PM

You would be overworking them and exceeding their abilities. Instead of atmospheric pressure, you'd be feeding it 8psi and expecting it to compress that more, when it can hardly do that with 0 atmospheric pressure. I don't believe it could be done without swapping hardware.

DEZERTE 04-09-04 03:35 PM

when u say it takes 50hp to run the SC, are u saying that it saps 50hp or it requires 50hp... sapping 50hp would suck.

SonicRaT 04-09-04 03:47 PM

Basically, they're saying if you had the supercharger just flowing into a tank or something, it'd suck 40hp off the engine. But since it can help power itself, it removes that and then nets a gain, how big of a gain we can't tell until the car is dyno'd. But as it stands, it's definatly under 200hp as the injectors can't support higher without detonating.

wozzoom 04-10-04 09:19 AM


Originally posted by SonicRaT
Basically, they're saying if you had the supercharger just flowing into a tank or something, it'd suck 40hp off the engine. But since it can help power itself, it removes that and then nets a gain, how big of a gain we can't tell until the car is dyno'd. But as it stands, it's definatly under 200hp as the injectors can't support higher without detonating.
that's exactly what we're saying. There is no such thing as free HP! :p:

This is why the propper ammount of fuel is so important. Assuming you're adding ~60-70 HP to the total output of the engine. (40 of that is being used to power the SC, 30 is going to the wheels) The stock NA fuel system CAN NOT handle 70 more HP!

Peruvianrx7 04-10-04 10:18 AM

HOLY SHEEEET!!!!and I thought all the rotary gods had blown an apex seal...

Zbrown is my new Master Enthusiast!

P.S. I dont know if you answered this... but do you have an intercooler hooked up or thinking of buying one? Also I would not attempt this just cuz I would want to get a rebuild turbo 2 tranny, and a better clutch just in case my old stuff blows up so my price would be around umm 1300 bucks or something still good as hell...

DEZERTE 04-11-04 10:54 AM

do we get some specs/pictures of the bracket :D?

DCRotor 04-11-04 06:33 PM

well i have some pictures but i need more info ( see my post on the third page). Right now im working on the TB braket. All that is left is to fabe the mounting braket and make the other pictures more acurate.
\mm/
-B-

surfpac 04-12-04 10:40 AM

Any more pics? I'd like to see some with the piping in place and the V belt pulley.

wozzoom 04-13-04 08:22 AM

New question: Vacuum Source

The Fuel Pressure Regulator requires vacuum to operate. Since the intake manifold is now pressurized under boost, the FPR will no longer function. Correct? Should the vac source for the FPR be re-routed? Where to? Before the SC?

Next Question: Relief Valve

Would the stock TII relief (blowoff) valve be enough for this setup?

are_one 04-13-04 11:45 AM

Im know Im late, but DAMN!!!!! That is one of the greatest mods I've ever seen for our cars, Im going to nominate you for the Nobel prize. Your excellency, could we please get a write up, please!

SonicRaT 04-13-04 11:53 AM


Originally posted by are_one
Im know Im late, but DAMN!!!!! That is one of the greatest mods I've ever seen for our cars, Im going to nominate you for the Nobel prize. Your excellency, could we please get a write up, please!
What more do you need that's not already here?

wozzoom 04-13-04 12:42 PM


Originally posted by SonicRaT
What more do you need that's not already here?
Exactly. zBrown was the guinea pig. He did the initial install and inspired all of us NA owners. Some people are already following in his footsteps.

If you don't feel like doing the engineering to make this project work yourself, then you'll have to wait till someone finishes their install and posts their work.

Can we please quit it with the posts requesting a "write-up"?

gerbraldy 04-13-04 01:03 PM

I'm gonna put a s/c on my 88 vert ass soon as I get the s/c. I can make any brackets for anything, have a bunch of 1/4" steel and cutting and welding torch. The only this is, will my afm still actually work proparly?

SonicRaT 04-13-04 01:35 PM

The only thing missing is how to make the bracket itself, which is 'CUSTOM', I'm not a fan of the way it was setup though. I'd of attempted to use the airpump's mounting points, as well as the intake bolts to fab something up, a little easier and more workable in my opinion.

DEZERTE 04-13-04 02:29 PM


Originally posted by scathcart
And run out of steam big time on the top-end...
are u saying its going to "run out of steam" more-so than if there were no SC?

wozzoom 04-13-04 02:34 PM


Originally posted by SonicRaT
The only thing missing is how to make the bracket itself, which is 'CUSTOM', I'm not a fan of the way it was setup though. I'd of attempted to use the airpump's mounting points, as well as the intake bolts to fab something up, a little easier and more workable in my opinion.
I would think that the ACV bolts on the lower intake manifold would make a great mount for a bracket...assuming of course that you removed the ACV.

the air-pump mount is a little to far forward to use as a primary support, plus the aluminum waterpump casting there is prone to breaking.

that leaves the intake itself and the engine mount.


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