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1990 Seville 4.5L PFI

Old 04-29-2016, 07:09 PM
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Default 1990 Seville 4.5L PFI

Anybody have a 0-60 time for one of these cars?

I've been tweaking and messing with mine since I got it back in 2003. I always knew the 4.5 and 4.9 engines had more potential than their stock, factory tuning. My grandma no longer drives, her 1991 Seville with 4.9 engine has now become my daily I had taken it when it was due for emissions and got it running correctly. It passed. My 1990 passed. Both with flying colors. Of course, to get it to pass, had to retard ignition timing otherwise they'd surely fail on the NOx. My 1990 is in much better condition, albeit it has higher mileage, I take care of my cars. I had my windows tinted...the 1991 did not, and the sun did a number on the interior. Baked the leather to a crackling crisp and discolored the dash and door panels. She never waxed her car and paint is popping all over. Sad, because the car only has 60,000 miles on it. Summer project.

I looked up the 0-60 times for some Cadillacs, perhaps factory listed times. For the 2002 Eldorado ESC, it lists 0-60 in 5.7 secs and 1/4 mile 14.2. I can't verify this, but, the same information also said the 2004 DTS with vin 9 engine had a top speed of 142mph..or 146...I forgot exactly, and on a trip out west in a 2004 DTS vin 9, I can verify that. So I trust the numbers listed are fairly accurate. The 1990 Cadillac Allante, 4.5 engine, 2 door coupe, which is lighter than a 4 door Seville - not to mention the allante was known for it's intake and higher output than what was put in the 90 sevilles and devilles...listed 0-60 in 8.1 secs.

If you read my post on the Cadillac Sail-on problem finally solved...I posted a pic of my 90 Seville and listed all the mods I had done to it. Nothing major. Your basic tune up, plugs, wires, cap + rotor....etc. I am running base timing at 14 degrees, 93 octane gas, factory base idle untouched gives me a curb speed of 525 ish rpms...I disregarded the TSB of lowering that to 450rpms to fix sail-on conditions, and have my TPS adjusted to 2.1 degrees at curb, 15.8 degrees max ISC extention, plunger gap .043"...I run a K&N air filter, denso O2 sensors, I opened the bottom of the air box slightly as it most definitely is restricted from factory...I understand that pulling in hot air from under the hood does no good, but, drilling 2 or 3 1 1/2" holes in that airbox increased midrange power, if you put your hand over the holes and blip throttle, you can feel it sucking. Not enough passage into the air intake from behind the headlight. The timing advance makes a huge difference. My TPS setting is probably the ideal combination for power enrichment and shift points without any sail-on condition or coast down angle problems. I replaced factory injectors with 19.5# accel. Like I said, no major surgery just routine repair and maintenance and some slight tuning.

Car had sat in storage all winter. I took it out, with stale gas (or at least, gas I had added some marvel to as stabil just doesn't work as well as marvel IMO), I ran a 0-60 time under 6 secs. I didn't smash the pedal down, as i did not wish to burn my tires, but a firm push to 20mph and WOT....I clocked the speedometer with my cell and watched the counter. It did a clear 5.9 sec 0-60, perhaps it could shave that with fresh gas...or if I smash down the gas pedal and bite in.

I have raced my buddy's DTS in the past, and it will take a N* up until 70mph where the 4 valve engine can breath.

Wondering what kind of performance others are getting out of your 4.5 and 4.9 cars. To me, getting a 4 door sedan that weighs quite a bit to do 0-60 in 6 or under is quite good. I will continue to tinker until I can't get it any better. Although, I probably can't get it any better than it is. 4.5L engine outperforms the 4.9L Seville. The 4.9 should have an edge on the 4.5....I am going to have to investigate that. I think there may be an exhaust restriction. The 4.9 is very torquey off the line, but bogs in the 30-50mph (2nd gear really) area where my 4.5 rips right through it. The stroked engine no doubt is going to have more low end torque, but, I haven't romped on my 4.5 to compare as I have brand new rubber on it. But before I changed tires I know it will easily light them up.

Anyone else have 0-60 times? Any performance mods you'd like to share?
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