Generally, when you pick fuel injectors, you need to guess how much HP you will be making, and work backwards.... a real PITA, but the only real way for guys who don't have an unlimited budget to try every injector on the market:crazy
Changed 58mm for 48mm, raised fuel from 44-47psi and put on Ram Air
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UB2 SLOW
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I set the Fuel pressure down to 45. Ed Wright programmed the computer to 47psi. I went with the 30# injectors and the 58mm, because Pace Performance said that was the best combo to run with their kit. Since I have taken off the 58mm and put the Ram Air on with the 48mm the car is running better. The Idle is now about 200rpms higher and the car has an eratic idle when cold. It jumps up and down and then smooths out some one it warms up. The engine is not running as smooth as I think it should, but I am not sure if this is due to the cam or something else. I changed the plugs again, but I really did not notice anything. I put a new opti on it when I had the engine out, so I hope I did not get a lemon. All the plugs are tight and I did not notice any arcing.
your cam will give you a bit of a lopey idle... What heat range plug did you go with? I probably would have gone 1 range higher because of the added power... It sounds like you are running a better mix now... that rough idle is actually a good sign... have you used the G-tech again, now that you have the lopey idle? Also, I still think your 58 mm TB is overkill, but should work better than the 48, assuming a proper tuning... you may want to give it a try again.
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UB2 SLOW
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I went from BOSCH platinum to NGK 55. I plan on getting my hands on a 52mm as soon as I can. After that I dont know what else to try. I considered pulling the cam back out and putting it back in, but I dont think the cam is the problem. I have yet to find anyone that can tune the computer while in the car that lives in NC. I plan on going back to the track and seeing if the Ram Air and 48mm made a difference. The last time I G-teched after the TB swap I ran a 12.9 at 106. The best I did at the track was a 13.02 at 105.
The cam is fine, you just have a bottle neck at the TB, and a bottle neck in the exhaust... If you can live with the sound cut out the resonator, it shouldn't cost more than 50 bucks to put in straight pipe where the resonator is...
I think your computer is tuned pretty well... you are on the mechanical side of things until you can tune it up better... Your air/fuel ratio is the most important thing... with those big injectors, you could probably run 40 PSI (because of the small TB)... also, what did you do to the MAF? i don't remember you saying anything about taking off the screens or going aftermarket
I think your computer is tuned pretty well... you are on the mechanical side of things until you can tune it up better... Your air/fuel ratio is the most important thing... with those big injectors, you could probably run 40 PSI (because of the small TB)... also, what did you do to the MAF? i don't remember you saying anything about taking off the screens or going aftermarket
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UB2 SLOW
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I pulled the screens out. When I had the Air/Fuel done on the dyno it read 13.0 at 44 psi. It started at 13.5 at 4400rpm and dropped slowly to 13.0 and stayed steady until 5500 rpm and then started to climb back to 13.5 until 6200 rpm. We got the most HP with this setting. I was told by Ed Wright that this was too lean and that I should raise the fuel pressure to 47 and I should have a AFR of 12.8. I would prefer to do something other than straight pipes. I already have the Muffler Eliminators on. I cant take the cats off due to emissions.
Agh, the dreaded emissions! Looks like you'll have to do some improvising or go to one of those expensive systems. I believe Basani (sp?) makes a 3" mandrel bent system for the LT1/4's. I also believe it's the least inexpensive, but it'll still drain your wallet of roughly $550 or so.
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UB2 SLOW
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There is a local guy who can make me a custom exhaust from the Cat back. I was thinking about losing the resonator and put on the best flowmaster mufflers I could find. He said he could make me a 2 3/4 in true dual. What do you think?
-=Jeff=-
Well-known member
I really think you need to invest in a scanner for your 96.. Like EASE or Datamaster or LT1 edit or something.
I have a feeling something is off. if you scan and datalog the engine info and send the info with the PCM back to ED he should be able to dial it in better. it is tough to do it without the car, but I think this will be one way to get the most power.
Also did you reset minimum air when you swapped to the 48mm TB?
I have a feeling something is off. if you scan and datalog the engine info and send the info with the PCM back to ED he should be able to dial it in better. it is tough to do it without the car, but I think this will be one way to get the most power.
Also did you reset minimum air when you swapped to the 48mm TB?
I think a true dual 2 3/4 is plenty enough. It can be debated that 3" is just excess for a 350. I think someone once told me that in a 3" exhaust system, the air would not flow smoothly through the system.
I think Flowmasters are great, I have them on mine and they sound great. I don't know in terms of comparison to the other mufflers how restrictive they all are compared to each other. Flowmaster is generally less expensive, but I think it's more because of the material rather than the quality of the product.
I think Flowmasters are great, I have them on mine and they sound great. I don't know in terms of comparison to the other mufflers how restrictive they all are compared to each other. Flowmaster is generally less expensive, but I think it's more because of the material rather than the quality of the product.
AFR of 12.8 is really rich.... Your attemt is to get it to 14.7, which is perfect (according to the numbers game) Your engine will already run better slightly lean (but it also isn't too good for your engine, so rich is safer)
I would drop your fuel pressure more, get your number closer to 14.... this will add some missing HP.
Exhaust:
Just make sure the guy is doing a good job, pipe bends kill flow.. the idea of cutting out the resonator was a temporary fix until you find what you like... also, Ecklers has a 3" KBD (mandrel bent) for about $500... that may be a better way to go? I don't know what the local guy wants to charge you.
I would drop your fuel pressure more, get your number closer to 14.... this will add some missing HP.
Exhaust:
Just make sure the guy is doing a good job, pipe bends kill flow.. the idea of cutting out the resonator was a temporary fix until you find what you like... also, Ecklers has a 3" KBD (mandrel bent) for about $500... that may be a better way to go? I don't know what the local guy wants to charge you.
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UB2 SLOW
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DOH.
I did not reset the minimal air. That is done by adjusting the throttle stop on the left side of the TB right? As far as the scanner, its on the X-Mas wish list. Unless someone can let me borrow or sell me one. 
I did not reset the minimal air. That is done by adjusting the throttle stop on the left side of the TB right? As far as the scanner, its on the X-Mas wish list. Unless someone can let me borrow or sell me one.
I am still looking into the scanner that hooks up to a palm pilot... It looks like it works really well, but I haven't found anyone that uses it.
-=Jeff=-
Well-known member
That Palm Pilot scanner is made by EASE. I use the Ease program with my laptop and love it.
I was looking at one from auterra, thanks for the EASE info... i just found their web site... The auterra software supports color palms and is cheaper than the EASE though... any palm users out there?
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UB2 SLOW
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How much does the ease program cost? I got the laptop already.
-=Jeff=-
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P-ColaVette
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Sluggish under 2500 RPM....
Hello UB2 SLO
I just wanted to get my .02 in on your problem. I haven't heard any other CAC members complain about losing the bottom end grunt of thier cars after installing the muffler elim's, however any street based engine has to have a certain amount of back pressure to operate efficiently, and be responsive to the throttle. We have a member here at CAC who is an engineer that was part of the team which developed the exhaust system for the C-5's, and what he has posted some time ago is that the optimum pipe diameter for LT4's is actually 2.75", not the 3" factory diameter. What he said was that every junction, such as the transition from Catalytic converter 2.5" back to 3" pipe, created a turbulence that ultimately restricts flow through out the entire system. Personally, on my LT4 powered car, I am still running factory cats, deleted the factory resonator and replaced with 2.5" pipe back to the factory 3" pipes out to a set of DynoMax UltraFlow mufflers, which are 3" in and 3" out. My car sounds good at low speeds, it has a deep rumble, and she really wakes up the nieghbors at full throttle. I would also say that resonance is non existent at highway speeds with this setup. To date, with this exhaust, I have run a 13.1@105 mph, and that was with a 2.2 60 ft time. My car has turned a 1.90 60 ft time as well. Hope this helps, and my apologies for the novel !
Steve
Hello UB2 SLO
I just wanted to get my .02 in on your problem. I haven't heard any other CAC members complain about losing the bottom end grunt of thier cars after installing the muffler elim's, however any street based engine has to have a certain amount of back pressure to operate efficiently, and be responsive to the throttle. We have a member here at CAC who is an engineer that was part of the team which developed the exhaust system for the C-5's, and what he has posted some time ago is that the optimum pipe diameter for LT4's is actually 2.75", not the 3" factory diameter. What he said was that every junction, such as the transition from Catalytic converter 2.5" back to 3" pipe, created a turbulence that ultimately restricts flow through out the entire system. Personally, on my LT4 powered car, I am still running factory cats, deleted the factory resonator and replaced with 2.5" pipe back to the factory 3" pipes out to a set of DynoMax UltraFlow mufflers, which are 3" in and 3" out. My car sounds good at low speeds, it has a deep rumble, and she really wakes up the nieghbors at full throttle. I would also say that resonance is non existent at highway speeds with this setup. To date, with this exhaust, I have run a 13.1@105 mph, and that was with a 2.2 60 ft time. My car has turned a 1.90 60 ft time as well. Hope this helps, and my apologies for the novel !
Steve
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UB2 SLOW
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Thanks, I am still debating what to do with the exhaust. You have made me think about something new. I will not be able to make any changes to the exhuast for a couple of weeks.
maxrevs85
Well-known member
Ub2, I have mensioned lately about a high idle problem and overall drivibility being not the greatest. Soooo, I changed out my 58mm TB for my stock 48mm and my idle problem went away and it is much better to drive . the low end throttle response is amazing. I can't keep the tires pinned down in first or second and thats from a 20 to 25 mph role. Lay down the throttle and it cooks the tires. I have lost some high rpm muscle which is to be expected. I related this to TPIS which i have been working with and they want me to send the 58 back to check out . They also told me i might need to use the 52mm they have tweaked more cfm out of. 940cfm I think. Terry the guy I talked to said he went from the 58 to the 52 also and it worked much better. he also has a 383 much like mine. Just thought I'd share this info.
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