Changed 58mm for 48mm, raised fuel from 44-47psi and put on Ram Air

UB2 SLOW · 09-07-02, 01:24 PM

Okay everyone, I dont have official results, but after taking your recommendations about swapping the 58mm to the 48mm, raising fuel pressure from 44 to 47 and putting the Ram Air on. The car feels allot stronger. The response is quicker also. I took the car out and did a 1/4 mile run with the G-tech. It showed 12.9 @107. The best I could do at the track was 13.02@105.89. Assuming the G-Tech is accurate, that is a big difference. The car is still sluggish below 2500 rpm. I think this is due to the LT4 Hotcam. I will swap the BOSCH for Autolites later. I am also thinking about going with a Cat Back instead of the Eliminators. What do ya think? Good or Bad Idea.
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BigRed · 09-07-02, 02:14 PM

Now Im still learning here but is there a way of advancing the timing so your not so sluggish off the punch?

I know onw way that'll guarantee a LARGE difference in acceleration. Use a Aftermarket Ignition box it'll deliver 60% more spark plus fire each plug not once but three times. I put the MSD 6A on my car and WOW what a difference.

Also my friend bought a 91 Stepside and he said out of all the mods he did to it (He spent like 4000) the MSD was the most noticable difference.

And for like 250 Bucks (300 with a Coil) you can't go wrong. You'll be pleasantly surprized.

BigRed · 09-07-02, 02:16 PM

Oh not to mention your going to GAIN fuel mileage! And I mean ALOT.

My car used to run around 21-23 MPG on the highway now its 25-28 MPG. It took me 1 1/2 tanks to get from Vancouver BC to Calgary Alberta. (If your not sure how far that is look at a map your be impressed.)

FX GS · 09-07-02, 02:48 PM

If you don't mind another suggestion, I would go with the NGK
TR55 spark plugs and why your at it, replace your plug wires with MSD 8.5 Super Conductors.

UB2 SLOW · 09-07-02, 03:03 PM

The only way I could advance timing would be to reprogram the computer. I dont have the software or the equipement to do it. I am still looking for someone in the area that does.

I am going to look at autolite and NGK this afternoon. Do you know what they cost?

I have been thinking allot about the MSD's. I plan on putting a supercharge on next. How will that combo work together? I only plan on runing 6-8psi boost due to a 10.2 compression ratio. If my math is correct, with 6-8psi I should have over 500hp at the crank and 430 at the wheels. This should put me deep in the 11's.

WhalePirot · 09-07-02, 10:07 PM

You can time the engine, static, after putting the ECM ignition timing in bypass. It is a brown wire on my car, near the distributor. The ECM assumes that this static advance is whatever the emission tag calls for.

I find the Delco plugs in my 406 work very well. Don't recall the #; sorry.

Anyone need a set of slightly run, Accel 265S plugs?

I may, also unload my unused MSD 6. I don't need it.

UB2 SLOW · 09-07-02, 10:32 PM

Got a new problem with the car. After raising the fuel pressure to 47 from 44, I now get codes P0171/P0174 system too lean, bank 1 and 2. I raised the fuel pressure to 48 and the idle increased and I still got the same codes after 50 miles. Any suggestions?

Edmond · 09-07-02, 11:43 PM

You could probably find someone to swap that 58 for a 52; look around. There's probably some guy out there who has a nice 52 that wants to upgrade to a 58.

I read that the Vortex is good for two tenths off the 1/4. There are a couple of reviews here in the forum for it.

If it were me, I'd stay with the eliminators instead of the catback.

BigRed · 09-08-02, 01:20 AM

What have you done about your O2 sensors? With all your mods especially regarding exhaust your O2 sensors are going to freak! TPiS sells a cheater plug to deal with them so they trasmit normal readings.

The MSD will actually complement the supercharger. With the added air your going to have added fuel so wouldn't be a good idea to have added spark? All the Twin turbo tuner guys run MSD's.

I run a MSD 6A, MSD 8.5 Wires, MSD Blaster 2 coil, Bosch Plat four plugs and Im very happy.

UB2 SLOW · 09-08-02, 08:42 AM

I think I will looking for an MSD in a couple of months. I am really strapped for $ after all of the mods.

I think I have found someone willing to swap TB's. If so great. If not Look out ebay!

Do the cheater plugs affect emissions?

Mad-Mic · 09-08-02, 06:17 PM

i run the bosch plat +4 plugs and man what a difference! car is strong all the way to 5000 grand but still got all stock stuff on her. this winter i'm gonna start modding it pretty good

UB, you can put a thicker gasket on for your heads if your gonna do the whole upper end (would be wise for the supercharger0 this will give you around 9.5 to 1 and a good piece of mind. superchargers are hard on the valve train!

Vettelt193 · 09-09-02, 09:06 AM

with the top end done up like you have it, you can kiss your bottom end goodbye with 6-8 psi... You have to realize a couple things about superchargers... when you buy one from a company, they are figuring your car is stock... so when they send you a pulley rated at 8 psi, and you put it on your high flow intake/heads etc. it will look like maybe 4 psi... Your setup, with a 6 psi pulley is how a friend of mine blew up his LT1 (and it only was showing under 4psi of boost). If you plan on supercharging, you have to stay under 5 psi because of the cam and heads.

about the codes.

I think your fuel pressure is so high now, the computer is fighting back with a shorter pulse... this is causing a bad spray and burn, so the computer thinks it is lean.... even when it tries to increase pulse, it gets a bad spray, further confusing the computer... since it increases pulse length without a better air/fuel mix, the computer thinks the pressure is too low. when you tuned the fuel pressure did you reset the computer first? It isn't easy getting the right pressure, especially since the computer runs differently when it is cold, when it is idling etc.

about MSD

LT1/4 engines have very good ignition systems, even with your setup, MSD is a waste of money. I have never seen an LT1/4 run faster with one, even with superchargers or cars set up like yours (L98 is a different story though)

Edmond · 09-09-02, 09:23 AM

So it would be useless to use the MSD on 92 and up while 91 and down would benefit? What kind of benefits would the L98 get from the MSD?

Vettelt193 · 09-09-02, 09:26 AM

the stock L98 ignition is fine for stock to mildly modified cars, but when you start getting into things, a modified ignition system can really help... all it does is make a better spark, so a cleaner burn... generally resulting in more power only if your engine isn't getting a solid burn as it is.... basically, if you start getting into fuel pressure adjustments on an L98, you could benefit from a better ignition.

Edmond · 09-09-02, 09:34 AM

Okay, so the lesson from all this should be that no matter how many mods and adjustments you've made, it all won't benefit much unless you get the brains in the car reprogrammed to work with the muscle. Am I on the right track here?