Acceleration

Q&A: Performance Technical Support
12 posts Page 1 of 1
ScottyC
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by ScottyC » Sat May 24, 2008 2:53 pm
ok... I find that my 97 sc2 has now gopt horrible acceleration...after adding a new header downpipe, high-flow cat. and 2 1/4 piping and my aem short ram it feels like i have lost alot of acceleration... what kind of mods or chnages can i make to produce better acceleration.... maybe remapping the ecu on the dyno......what you guys think is best way to improve acceleration. now i did add new plugs and ngk wires.... ill throw that out there to did i do somthing wrong or should i add more...

 

sc2_projekt_97
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by sc2_projekt_97 » Sat May 24, 2008 7:40 pm
you sure the Cat is installed facing the correct direction?

and you can not remap a saturn PCM. its stock and always will be, there is no way to change it.

 

PurpleRain
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by PurpleRain » Sun May 25, 2008 9:55 am
I don't know if it would affect it, but either way, you didn't use platinum plugs did you????

 

ScottyC
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by ScottyC » Sun May 25, 2008 12:32 pm
nope....how much of a difference would that make
......why cant you remap a saturn ECU

 

inflames625
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by inflames625 » Mon May 26, 2008 4:22 pm
i think i read that the saturn ECU's are all eeprom protected. I could be completely wrong because I used to work with modding xbox's and found they are too eeprom protected but is easly bypassed. i could be getting them mixed with each other. ....though sc2racer has a modded ecu. He told me he found a place but its outta business or something. good luck.

 

Stace
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by Stace » Tue May 27, 2008 10:11 am
platinum plugs melt at high revs, causeing too much unburned gas to enter the cat. This will cause the cat to melt.

manny of people have tried to reprogram the eprom but as far as I know NOONE has done it..except for moving the rev limiter.

try the geo TB mod mabye..

Saturns dont run well in dry heat, the pcm will mess with the timing if its hot and dry out. I found acceleration sucks in hot summer days. a mod that has worked but got lots of conserversy is the air intake risister mod. It wont get you awsome performance but it may trick the pcm in thinking its cooler out and stop it from messing the timing. Do your reasearch on this idea tho. and dont listen to half of what people say about it. Drag racers DO use it to gain a hundredth of a second on the 1/4mile.

 

sc2racer
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by sc2racer » Mon Jun 02, 2008 2:08 pm
Yeah I had my ECU worked on before but a shop in Toronto that has gone out of business, they took my comp for a winter a few year back and sent it to a manufaturer of chipping ECU's, they were also associated with AEM , which is why in my garage I beleive I started I have AEM software in my car.

The gains that I felt were awesome, you could really feel a nice pull in third gear, again research was the factor in me finding someone to chip my car, just don't go ahead with the first thing you find...So the moral is you can chip a Saturn as I had found out three or 4 years ago right when I got my car lol :)

I forgot what the chip did though, it had something to do with fuel and timing I beleive, it was such a long time ago I don't remember lol

But yeah check the cat to see if it's backwards .. I would have to agree on that one too lolol:)

 

slammedsl1
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by slammedsl1 » Mon Jun 02, 2008 2:53 pm
My exhaust is 2.5'' catback and I have no power under 3.5k with the mp2, but after that, the thing litterally pulls, feels pretty neat.
DaFuzzTSU
by DaFuzzTSU » Fri Sep 26, 2008 3:32 pm
!!!First things first. I am a newbie here so if this is retarded and a waste of your time I apologize!!!

anyway

Here is what I know that may relate to your problem. Your big lack of low end acceleration was noticed after adding several high flow exhaust components to your car most of which have I.D. of 2.5". This could very likely be due to improper pipe sizing for your application/too much flow. The explanation (which a lot of you may already know, I don't know)...

A car's ideal power range is greatly affected by the components in an exhaust system. if your exhaust system is too constricted it will stifle your engine, and ruin the volumetric efficiency of your engine. If your exhaust flows too freely it will not provide adequate back pressure to maintain the proper pressure gradient for your setup and your engine will sputter, and more than likely burn some piston rings, or gaskets.

What does this translate to in the performance tuning world?

A car whose exhaust is more restrictive (generally pipes with I.D. of 1.5" to 2.5") will yield a better efficiency in the lower RPM range, and then lose this effectiveness steadily as the RPM's rise. The reverse is true for a very free flowing engine (2.5" + pipe I.D.). The low end RPM's will be weak due to a lack of back pressure, but as your engine winds up and the exhaust gases begin to fill out the piping and create steady full volume flow the engine's effectiveness will increase.

From what I have been told for NA you want an I.D. of 2.5" or less, and for FI you want somewhere around 3.5", and this is for a larger engine than our rolling tupperware typically packs under the hood.

So, in closing, my not so expert opinion would be that you have too much freedom of flow in your exhaust piping/components and as such your acceleration will likely suck, but your top end performance should be pretty reasonable. This is likely what slammed sl1 is experiencing judging from his post. so hopefully this helps, and if it's all just elementary crap that you all knew before I was even born I am sory that I cluttered up your forum with my nonsense.

 

Slayer
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by Slayer » Sun Sep 28, 2008 12:45 pm
Da Fuzz, your replies werent shown becuse you werent a verified member yet.. (you are now) and i deleted your first post because it looked ilke a repeat of this post, but with less info. So anyways you wont have to wait for any replies to be posted from now on.

 

DaFuzzTSU
by DaFuzzTSU » Sun Sep 28, 2008 7:58 pm
thanks for the heads up, I was wondering if that was the case.

 

Viperoni
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by Viperoni » Sun Sep 28, 2008 9:51 pm
DaFuzz, 2.25" has been proven to be a good size for Saturns.
IMO it's better to stick to 2.0" before the cat, but it's probably too late for that now.

Also, you NEVER want restriction or backpressure in your exhaust. You want an optimal level of Exhaust Gas Velocity to help suck out the exhaust charge from the combustion chamber. Too much EGV hurts as much as too little.

slammed's exhaust is simply too big.
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