barely noticed change after mods

speedfreak

Registered User
I have 90SC with an AOD. The early style blower has been ported nicely(sound ports filled, and triangular opening has been opened about a quarter inch all the way around) the inlet was also ported as much as it could be, and the inlet tube was ported to match. I have a custom blower top that allows the use of the whole 3 inch outlet tube(has no bottle neck at all). I have a cold air induction kit (inside fender style). I have a Racer Walsh overdrive pulley, which I believe is like 12%. The exhaust consists of removed cats, flowmaster resonator kit, and stock rear pipes finished off with thrush turbo mufflers. I did all of this and the car barely feels faster. I get about 15 lbs of boost right before shifting. I know the boost is probably where is should be, because of the less constrictive exhaust, but I really thought these mods would give at least some "seat of the pants" power increase. Does this sound right, or do I have a problem?
 
speedfreak said:
I have 90SC with an AOD. The early style blower has been ported nicely(sound ports filled, and triangular opening has been opened about a quarter inch all the way around) the inlet was also ported as much as it could be, and the inlet tube was ported to match. I have a custom blower top that allows the use of the whole 3 inch outlet tube(has no bottle neck at all). I have a cold air induction kit (inside fender style). I have a Racer Walsh overdrive pulley, which I believe is like 12%. The exhaust consists of removed cats, flowmaster resonator kit, and stock rear pipes finished off with thrush turbo mufflers. I did all of this and the car barely feels faster. I get about 15 lbs of boost right before shifting. I know the boost is probably where is should be, because of the less constrictive exhaust, but I really thought these mods would give at least some "seat of the pants" power increase. Does this sound right, or do I have a problem?


Sounds like you have stock exhaust manifolds? If they are not at least ported (headers would be best) they could be holding you back regardless of what you have behind them. You are also running stock rear pipes and you have a lot more air going into the engine. Missing out on the "seat of your pants" feeling may be the least of your worries if you don't further open the exhaust. My .02.
 
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You can port that early model M90 and the inlet plenum till the cows come home and it still won't flow worth a damn. Replace the supercharger with a late model M90 (94-95) or an "S" port or even better an MPII. All of these superchargers will require a late model style plenum and for best results the Magnum Powers plenum should be used.

David
 
I know the 94-95 m90 is better, largely due to the fact the the inlet is rectangular and raised higher. I got my blower ported for free, so I had nothing to lose. At least it sounds like it's doing something now...lol. I also have an 89 5 speed SC that is completetly gutted right now, being prepared for paint(which is where most of my extra $$ is going right now) that's why I chose to try the ported stock blower first. The car ran 15.01 @ 89mph with just the cats removed. Two weeks ago it ran 15.46 @ 89mph,but it spun badly off the line. I got the 90 for free and later found out that the rockers are completely gone, but the 89 is clean and I want to do it right. Should I not even bother using the ported blower that I have on it?
 
Is your cold air induction shielded from the engine compartment or just a filter exposed to the engine compartment?

Since you didn't mention intercooler, are you are running a stock intercooler and no IC fan?

With the pulley you are using you might be overworking your IC.

The car should feel like you have more power in the first 1/8 and then your car will lay down in the last 1/8. It could be that your IAC temps are getting to high and the EEC is retarding your timing.
 
The early model ported blower will help and I was able to run high 13s with the one I had and a bunch of bolt-ons. But it would have been much easier if I had upgraded to a better blower before doing all the other stuff I did.

It's been my experince that the three mods which will yeild the most power increases are as follows.

The supercharger
The fuel system
The camshaft

Sure...things like ported heads, free flowing exhaust, gears and better intercoolers all help....but IMO they do not compare to gains from the mods I listed above.

David
 
besides the mods that I explained in the original post, it is completely stock. I would ultimately like to have the 5sp car in the mid 13s. What bolt ons did you have, using the ported stock M90, to get it in the 13s? Which cam should I use? What size injectors or fuel pump will I need? (by the way- the stock fuel tank will be gone, I will be using a 10 gallon aluminum cell with an inline pump.) I dont use the trunk and it will free up space for the exhaust.
 
Most likely you have tuning issues and you may be running out of fuel. Your mods sound nice but you need to make sure you have adequate fuel and a proper tune. You have changed enough things that your OE tune is most likely no longer valid. Some people have had success without it but it's a total crap shoot. Your car should have no trouble making 240rwhp and should feel really strong. I don't see an IC upgrade on your list. A double IC and a fan should be considered mandatory.
 
How do I get it retuned.........is there somewhere that could burn me a custom chip, just knowing the mods that I have?
 
your tune should be ok you may need bigger maf or throttle body or exhaust ports you can tune with the eec tuner
 
It seems people forget these cars are getting around 16 years old and fuel pumps dont last forever. The SC ran a way to small fuel pump from the factory so now add 16 or so years and the pumps just cant keep up. I have seen many SCs that run way lean totally stock, you replace the pump with a 255lph and now it runs pig rich. My point is take it to a dyno with a wide band and have them check the A/F. if they are a SCT dealer they can burn you a chip right there. If you plan to mod the hell out of it then look into a EEC Tuner - SC tuner, only problem with tuners is little support and no manual.
 
Upgrade your fuel pump and if you have more than stock boost you need more than stock intercooling. Once you have taken care of that situation then dyno the car (with AF) and post the results. Otherwise it's just guessing.
 
what about the snow performance injection kit? I know that this kit is mainly designed to inable you to run more timing, but would it not cool the intake charge more than adding a double IC and fan? Just wondering...considering it would be quit a bit cheaper and this car will in no way be an everyday driver.
 
Well, that is a good suggestion. I would recommend it for your situation. Yes, it will be more effective at cooling the intake charge than a double IC. I can say that with 100% certainty based on my testing. Then you can add the fact that it will increase your fuel octane rating to well over 100 octane which will reduce the need for a tune based on high boost. It will also offer a certain amount of protection against a lean condition but I will not make any claims as to how much.

I would still recommend getting to a dyno after you get the system installed to make sure that things are not too far out of range one way or the other.

Email me at the link in my sig if you want to go ahead with it.

David
 
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