New Supercharger installed! Need some advice on gears...

[01STG2ROUSH]

I just installed a Saleen Series II blower on my car and have a few questions I would like advice on. I will list the rellevant items installed and then ask from there...

Saleen Series II blower, 75mm Accufab TB, 42lb injectors, 90mm Lightning Mass air, Chicane Ripp Kit, 255 Fuel pump, LFP heat exchanger w/ twin Spal fans, Bassani X-Pipe, Magnaflow Mufflers, King Cobra clutch, and 4:10 gears...

Obviously those are the essentials for the question, so what I am wondering is whether or not the 4:10's are to low of a gear for a roots style blower. I just took the car out on it's first drive " NOT TUNED, so driving was minimal". In any case it didn't seem to make boost "@10 psi" until about 4000 rpm in
3rd gear. I wasn't able to make a clean pull from 1st on up but quite honestly 1st and 2nd gear were so short I never really pulled above 5 psi. I'll be taking the car up to be tuned next week so maybe on the dyno I will be able to see or possibly when I get back if with a proper tune it will work out better but in the mean time I'll be wondering bout those 4:10's. Any input on what gears I should run? I'm kinda thinking 3:73's may be the way to go. Any input from you guys on this greatly appreciated. -Trent

 

[hotmustang331]

Depends on how much power I guess....from what I can tell, you will want some 3.73s. Its not a good idea to go into boost before you get it on a dyno, or have a wideband and an X cal to reduce timing and add fuel if needed.

 

[01STG2ROUSH]

Depends on how much power I guess....from what I can tell, you will want some 3.73s. Its not a good idea to go into boost before you get it on a dyno, or have a wideband and an X cal to reduce timing and add fuel if needed.

I can't emphasize enough how gentle I was on it. It was maybe a half mile test lol. I'll be towing the car up to AZ dyno chip (bout 2 hours away) but wanted to make sure that it was going to work alright given that I bought the blower used off Ebay. I'm hoping to see 400 @ the rear when I'm done. The cars a convertible so as far as Drag racing I'll be kinda limited. It's more of a weekend fun toy with the occasional "Forbidden " street race mixed in... -Trent

 

[Dope 97GT]

i say 3:73's because the s/c will still make good boost down low not like a centrifugal s/c.

 

[hotmustang331]

I can't emphasize enough how gentle I was on it. It was maybe a half mile test lol. I'll be towing the car up to AZ dyno chip (bout 2 hours away) but wanted to make sure that it was going to work alright given that I bought the blower used off Ebay. I'm hoping to see 400 @ the rear when I'm done. The cars a convertible so as far as Drag racing I'll be kinda limited. It's more of a weekend fun toy with the occasional "Forbidden " street race mixed in... -Trent

Ok lol . What sortof tune do you have in the car right now?

 

[01STG2ROUSH]

Ok lol . What sortof tune do you have in the car right now?

Right now it's the stock tune from Ford. It was a stock Stage 2 Roush so I don't think there were any changes made to it as far as I know. The car is running pig rich with the new setup and as I mentioned before, a clean pull was out of the question as it is nowhere close to where it needs to be as far as a tune...

 

[hotmustang331]

WOW you are the luckiest people alive! That motor should have blown sky high @ 10 PSI for any amount of time lol...I bet your A/F was in the 15+ range or worse. No doubt it had detonation, guess it wasnt enough to blow the motor.

Again, you are VERY VERY luck....and please dont go WOT at all...or even remotely close to it until your tuned.

 

[jstreet0204]

WOW you are the luckiest people alive! That motor should have blown sky high @ 10 PSI for any amount of time lol...I bet your A/F was in the 15+ range or worse. No doubt it had detonation, guess it wasnt enough to blow the motor.

Again, you are VERY VERY luck....and please dont go WOT at all...or even remotely close to it until your tuned.

He has the stock tune with 42's so he was WAY rich, not lean. Either way he shouldn't be driving it, much less going into boost without a tune.

To the orginal poster, I run 4:10's with the same supercharger. I was running drag radials which made it much better. With the 4:10's it will appear to not make boost down low, but it really just because you don't stay in the lower rpm band long enough to make full boost. I seldom see 8psi in 1st or 2nd, but see just over 10psi in 3rd and 4th.

 

[Dope 97GT]

To the orginal poster, I run 4:10's with the same supercharger. I was running drag radials which made it much better. With the 4:10's it will appear to not make boost down low, but it really just because you don't stay in the lower rpm band long enough to make full boost. I seldom see 8psi in 1st or 2nd, but see just over 10psi in 3rd and 4th.

so would you say 4:10s are too much for the setup or do you like it getting through the gears that quick?

 

[Kilgore Trout]

Do not drive without at least a handheld programmer tune

If you can afford a blower you can afford a handheld programmer...

Anyways, you should go with 3.73 gears.

 

[jstreet0204]

so would you say 4:10s are too much for the setup or do you like it getting through the gears that quick?

I like 4.10's when I have the drag radials on I've got some pep boy tires that I put on there last weekend to get me through the winter, and they suck.

 

[01STG2ROUSH]

He has the stock tune with 42's so he was WAY rich, not lean. Either way he shouldn't be driving it, much less going into boost without a tune.

To the orginal poster, I run 4:10's with the same supercharger. I was running drag radials which made it much better. With the 4:10's it will appear to not make boost down low, but it really just because you don't stay in the lower rpm band long enough to make full boost. I seldom see 8psi in 1st or 2nd, but see just over 10psi in 3rd and 4th.

Just to clear this up "I did not beat on the car to all ends of the world." it was a drive around the block with an entirely new setup to confirm proper operation before I tow the car for two hours to go get tuned. It's running PIG RICH with the new injectors so to go lean is not a worry at this point. I was in boost for such a short amount of time that I actually began to wonder about my original question of how the gears might be responsible for this though I am not sure. The car has Drag radials on it and as of now I am thinking it would be performance beneficial to swap to the 3:73's... Any others?

 

[hotmustang331]

He has the stock tune with 42's so he was WAY rich, not lean. Either way he shouldn't be driving it, much less going into boost without a tune.

To the orginal poster, I run 4:10's with the same supercharger. I was running drag radials which made it much better. With the 4:10's it will appear to not make boost down low, but it really just because you don't stay in the lower rpm band long enough to make full boost. I seldom see 8psi in 1st or 2nd, but see just over 10psi in 3rd and 4th.

I believe roush has a performance tune from the factory. There is absolutly NO gaurentee that he was rich. It depends on the pulse width...with a stock motor, the pulse width on the stock injectors would be pretty low. Depends on what the pulse widt if the 42s would have to be at...none the less there is no sure fire way to tell.

Also dont forget about the timing man...its running N/A timing with 10#s of boost being shoved down the engine. Ill stand by my statement that he was lucky as heck. Im just glad nothing happened.

I just want any peeps reading this to NOT think that they can shove 42# injectors in their motor, bolt on a S/C and have at it because its going to be "rich" . Its all speculation until its on the dyno....better to be safe than sorry IMHO.
Good luck and keep us updated on the progress

 

[Superhereaux]

pulse width being equal a 42#er will spray more fuel than a 19#er



i knew a guy in tech school who had a procharged zo6 with 42# injectors and no tune and that thing was stupid rich

 

[01STG2ROUSH]

I believe roush has a performance tune from the factory. There is absolutly NO gaurentee that he was rich. It depends on the pulse width...with a stock motor, the pulse width on the stock injectors would be pretty low. Depends on what the pulse widt if the 42s would have to be at...none the less there is no sure fire way to tell.

Also dont forget about the timing man...its running N/A timing with 10#s of boost being shoved down the engine. Ill stand by my statement that he was lucky as heck. Im just glad nothing happened.

I just want any peeps reading this to NOT think that they can shove 42# injectors in their motor, bolt on a S/C and have at it because its going to be "rich" . Its all speculation until its on the dyno....better to be safe than sorry IMHO.
Good luck and keep us updated on the progress

I would assume the black smoke would be a good indicator of running rich... I also wouldn't say that I went out to "Have at it"...
I appreciate the concern though...

 

[hotmustang331]

That last statement wast directed at you. People will see that you went WOT and its ok, and figure that they will be safe to go WOT all the time.

Its going to be STUPID rich durring cruize and part throttle, because it thinks it has 19s...so its spraying WAY too much fuel. Im concerned with WOT...10PSI of boost is ALOT of air going into the cylinders.
I was saying that it may have not been rich the brief moment you saw 10PSI. Sorry may not have worded that correctly.

Yep, no problem...I like to keep people safe. Last thing I want is for someone to loose an engine.

I just dont want the situation to be taken lightly by any other readers...im not trying to come down on you or anything LOL.

 

[jstreet0204]

I believe roush has a performance tune from the factory. There is absolutly NO gaurentee that he was rich. It depends on the pulse width...with a stock motor, the pulse width on the stock injectors would be pretty low. Depends on what the pulse widt if the 42s would have to be at...none the less there is no sure fire way to tell.

Also dont forget about the timing man...its running N/A timing with 10#s of boost being shoved down the engine. Ill stand by my statement that he was lucky as heck. Im just glad nothing happened.

I just want any peeps reading this to NOT think that they can shove 42# injectors in their motor, bolt on a S/C and have at it because its going to be "rich" . Its all speculation until its on the dyno....better to be safe than sorry IMHO.
Good luck and keep us updated on the progress

I agree nobody should be hitting boost untuned, but he was definately rich. There is no speculation about it. When the eec calculates pulsewidth, it needs to know the injector size. The larger the injector, the shorter the shorter the required pulsewidth to deliver the same amount of fuel. The difference between the pulsewidth for 19's and 42's is about 40%. The LMAF he was also not tuned for will lean it out some, but not enough to make up for that much extra fuel.

 

[jstreet0204]

Just to clear this up "I did not beat on the car to all ends of the world." it was a drive around the block with an entirely new setup to confirm proper operation before I tow the car for two hours to go get tuned. It's running PIG RICH with the new injectors so to go lean is not a worry at this point. I was in boost for such a short amount of time that I actually began to wonder about my original question of how the gears might be responsible for this though I am not sure. The car has Drag radials on it and as of now I am thinking it would be performance beneficial to swap to the 3:73's... Any others?

I say just keep the 4.10's for a while until you get used to it. If you still don't like it change them. I have no plans on changing mine. They are great on the highway. It will go from 65 to 110 in no time, and with the drag radials traction is not terrible.

 

[John Smith]

I used to have 4.10s with my setup but found that they were too low. First was way to short, almost to the point of being useless. You dont need 4.10s to get a Roots or Screw type blower car off the line. I have since switched to 3.73s and I am much happier this way. I have first gear back, and can cruise comfortably at 50mph in 4th gear now. You will still be able to pull on the freeway with the 3.73s up to and beyond 110mph. Fifth gear may not feel as strong as with the 4.10s, but you will actually be better off dropping into 4th.

 

[Pennywise2]

FRPP 3.55's will help alot with any traction issues.
I wouldn't go with too low of gears with a Saleen
blower.