Pulley Question

acb92sc

Registered User
I Am Putting A 95 Blower And 36 Lb Injectors On 89 Sc, Along With A Custom Fmic. I Have A Full Exhaust, 255 Lph Pump, And A Cai. I Did Not Get A Pulley With The New Blower, And All I Have Is The Overdrive Pulley From My 89 Blower. I Am Not Sure If It Is A 5 Or 10% Pulley. It Is 3" Diameter. Can I Safely Use This With The Newer Blower And My Current Setup Or Do I Need To Find An 89 Pulley To Overdrive The Newer Blower?
 
I've done this swap myself. first thing that I'd do is not use the injectors unless you get a tune. You can use an OD pulley, but you've got to get your computer tuned to be using the correct fuel. I do not know how much 30-36 injectors would affect the a/f ratio, but I don't and would not recommend anyone changing the injectors without an immediate tune. If you're getting it tuned, the the OD pulley will be fine. Even without a tune and keeping the stock injectors you should be fine. It's when you start messing with the injectors that you start running into serious a/f ratio issues.
 
Getting...

You cannot use a PCM from a 95 in an 89. The processors are not compatible. I would use the stock injectors for now, install the blower, the pulley is a 5% which is a 8% overdrive on a 95 blower. I would look for a 89-93 pulley for the 3% overdrive as this will help your long term motor health.

Then, look into getting someone that can tune the car and get the goodies that you might want.

I do not like the 10% overdrive on ANY stock blower....Just my .02


Don
 
It's not a direct bolt in...the pins may line up, but on a '94+ the computer controls the transmission, and there's a lot of other things that are not the same. Way too much to swap out the EECs. I used a ported '95 supercharger with a 5% pulley with my 30 lb injectors and it worked fine up to about 250-255 rwhp. Only at that level and about 5200 rpm did I start to run out of fuel, thus requiring larger injectors. If I were you, I'd stick with the stock injectors and try to find a pulley that you can live with (no more than 5% which is about 8% OD on the late gen M90s). Then get some dyno time to chech your air/fuel ratio to make sure that it's still safe.
 
36 lb injectors

007_SuperCoupe said:
first thing that I'd do is not use the injectors unless you get a tune. It's when you start messing with the injectors that you start running into serious a/f ratio issues.
You can run 36 pound injectors, with your '89 computer (w/o a special tune), as long as you use a 36 lb. sampling tube in the (aftermarket) MAF, or use the late model MAF. Been There, Done That, it's not a problem at all!!!

It seems like the current "Hip" thing to tell everybody that they Must have a tune. "I' bought new tires", "OMG, Don't run it till you get a new tune, to compensate for the different rubber compound"!!!!!!

68COUGAR
 
68COUGAR said:
You can run 36 pound injectors, with your '89 computer (w/o a special tune), as long as you use a 36 lb. sampling tube in the (aftermarket) MAF, or use the late model MAF. Been There, Done That, it's not a problem at all!!!

It seems like the current "Hip" thing to tell everybody that they Must have a tune. "I' bought new tires", "OMG, Don't run it till you get a new tune, to compensate for the different rubber compound"!!!!!!

68COUGAR
All the 91 up 70mm MAFs have the same transfer function. You can't drop in a 94 SC MAF and run 36# injectors.
 
Ok, I Get It.... Call Dave. Lol. On To The Second Part Of My Question: What Blower Pulley Do I Have If It Is 3" Diameter On The Outside Of The Grooves?
 
68COUGAR said:
You can run 36 pound injectors, with your '89 computer (w/o a special tune), as long as you use a 36 lb. sampling tube in the (aftermarket) MAF, or use the late model MAF. Been There, Done That, it's not a problem at all!!!

It seems like the current "Hip" thing to tell everybody that they Must have a tune. "I' bought new tires", "OMG, Don't run it till you get a new tune, to compensate for the different rubber compound"!!!!!!

68COUGAR

When giving advice you err on the side of caution. I've seen a couple guys here do a few mods then run it for 3k-6k miles only to blow their HGs because they were off on the A/F ratio. One guy as he was driving to a tune, the other guy, the day after the tune. $325 + dyno time for a tune or much more for changing head gaskets? I'm going to tell everyone to get a tune every time. It's just good advice.
 
i AGREE....

I was running my 95 5-speed and thought it was all running great with the MPIII on it. I had the MPII and same mods. All I changed is teh double IC and the blower and TB. I was 13.8-1 under boost. This is considered dangerour territory by ANYONE that knows about forced induction motors. The air/fuel ratio you opt to achieve is about 11.5-11.8 to 1.

The other fact is that the calibrated MAF's that C+L sells are calibrated close, not exact. Only running the car with a sniffer or wide-band O2 will show actual air/fuel ratio. Those of you who remember carburators will remember the days of re-jetting a carb so that you got the proper air/fuel and then messing with the mixture screws to get it right.

No different except that the chip is the jets and some is remotely turning the screws.

Don
 
One Other Thing I Dont Get Is How Adding Bigger Injectors Can Make The Car Run Leaner? Doesnt Add Up In My Thinking, Anyway.
 
acb92sc said:
One Other Thing I Dont Get Is How Adding Bigger Injectors Can Make The Car Run Leaner? Doesnt Add Up In My Thinking, Anyway.

More than likely it won't, however, it's worth noting that you can cause just as much damage running rich as you can running lean.

And since you have more mods that you are looking at doing, you could very well end up with a lean condition. If you did nothing else but install the injectors on an otherwise stock car, then you'd be rich...but if you perform mods from the intake back to the supercharger, you can find yourself in a lean condition in a hurry.

I recommend a tune, because I hate to be the person who says "told you so" but it's happened more than once, and I don't hesitate to say it. Learn your lessons from others, not yourself. That's my advice. Ultimately you will do whatever you want to regardless of what you hear here. If you're A/F ratio is off and it causes damage, there's no one to blame but yourself. That's the way I see it. It may be rough, but that's kind of how I am at times.
 
I See... I Hope To Somehow Get Hooked Up W/ Dave Dalke,but Who Knows When I Can Get In Touch W/ Him. Im Sure Id Have To Drive To Him, And From Teh Sounds Of It, I Dont Want To Risk That, Even. Torture, I Tell You, Torture.
 
A x B = C & D x B = C, Then A = D

Shockwave said:
All the 91 up 70mm MAFs have the same transfer function. You can't drop in a 94 SC MAF and run 36# injectors.
If the early & late transfer functions are the same, and the early models have 60mm MAF w/30# injectors, & the late models have 70mm MAF w/36# injectors, then explain why you can run 36# injectors & 70mm MAF, on the early (same) transfer functions?

68COUGAR
 
because the calibration is in the computer not the MAF. And in '91 they went to the 70mm MAF with 30lb injectors and didn't upgrade the injectors until '94. That is why you can take a MAF from a late model and directly bolt it into an early model...the functions are in the eec, not the MAF. The injectors is where you run into your issues.
 
I thought the early ones were 55mm, but that's neither here nor there. I think what Sam is saying is, why not play it safe so it doesn't BITE you in the wallet later. A tune is a lot cheaper than doing head gaskets or whatever other problems you might encounter from not getting a tune.

When I finish getting mine together, I need to get one myself. I haven't changed injectors, but did some other bolt ons. And I'd rather be safe than sorry.
 
All Right, One Last Q- If I Get It All Together, Take It To The Dyno, And My A/f Ratio Is Good Across The Board, It Would Be Safe To Drive Then, Correct? Or Is There Something Else To Worry About, Too?
 
acb92sc said:
All Right, One Last Q- If I Get It All Together, Take It To The Dyno, And My A/f Ratio Is Good Across The Board, It Would Be Safe To Drive Then, Correct? Or Is There Something Else To Worry About, Too?


I would say that you are OK if all is good. A good A/F is between 12.0-1 and 11.0-1. Make sure it's the same all the way across the board.

Then go to town!!!!

Don
 
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