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Good performance mods for 3.4L DOHC


derrick

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I have a 94 cutlass supreme 3.4L DOHC and i am doing mods like dynomax mufflers and cat converter dogbone(motor mount) cold air intake underdrive pulleys and a chip but i looked and i can not found a chip for my year of motor or car please help with information on a chip/pcm.

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:oops: i missed that big time :lol: unless you wanna drive to ben's and lend him the car to make a chip, otherwise....sol on chippage

 

All of the major chip manuafacturers (Hypertech, Superchips, JET, Fastchip etc) make chips for 94-95 LQ1's...........

 

They don't make any power though (<1whp), nor do they usually change the shiftpoints.............basically they are an expensive governor delete.

 

 

 

 

 

My advice to "derrick" is to learn to drive his car first.........how to launch and where/when to manually shift........that should be step #1.

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BIGBULS, I would not take your advise. A 3.4L/auto will be faster shifting at 6,000rpm rather than 7 on a stock motor. I would just let it shift. The power fall off after 5500 on a stock 91-95 is huge.

 

As for launching, it isn't hard. Powerbrake to the max....

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BIGBULS, I would not take your advise. A 3.4L/auto will be faster shifting at 6,000rpm rather than 7 on a stock motor. I would just let it shift. The power fall off after 5500 on a stock 91-95 is huge.

 

As for launching, it isn't hard. Powerbrake to the max....

 

thats only true for the 91-93... the 94-95 the power dosnt fall off until 6k. and the 96dont fall off until 7k.

 

I have to admit for being a DOHC its quite torquey at mid rpms(3500rpms and up) in stock form but once you start modding it the higher rpms start to produce some nice gains with minimal loss of low end torque.

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BIGBULS, I would not take your advise. A 3.4L/auto will be faster shifting at 6,000rpm rather than 7 on a stock motor. I would just let it shift. The power fall off after 5500 on a stock 91-95 is huge.

 

As for launching, it isn't hard. Powerbrake to the max....

 

thats only true for the 91-93... the 94-95 the power dosnt fall off until 6k. and the 96dont fall off until 7k.

 

I have to admit for being a DOHC its quite torquey at mid rpms(3500rpms and up) in stock form but once you start modding it the higher rpms start to produce some nice gains with minimal loss of low end torque.

 

My '93 Z34 has a '95 engine in it, modded fairly well. Below 3500, it's kinda slow, but the gearing helps a ton. But, once it hits that mark, it's nuts. It kicks in like no other, and takes off. It really drops off around 6800-6900 rpm, but i let it go to where my FFP chips takes it(over 7000 rpm), mainly because it gets me better into the rpm range for the next gear.

 

Truthfully, now that I have my 96-97 intakes, I can't wait to get them cleaned up and swapped on. This car is gonna be a beast. I still need a UDP, and larger exhaust would help greatly. After that, nothing until next fall/winter :D

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I said on a stock motor, Sonyman's car probly has minimal drop off, mine pulls right to 7, and I'm sure the guy above me does the same. It isn't hard to do, but they need mods to do it. 94-95s were the same as 91-93s...Just with MAF...The chip does a lot for the post 5500 power curve for sure.

 

and larger exhaust would help greatly

 

No it won't. You might notice it becuz of your other mods, but you won't gain much at all.

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and larger exhaust would help greatly

 

No it won't. You might notice it becuz of your other mods, but you won't gain much at all.

 

Thats more along the lines of what I mean. With my other mods, a larger exhaust will help a ton. What I have now is pretty darn restrictive.

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BIGBULS, I would not take your advise. A 3.4L/auto will be faster shifting at 6,000rpm rather than 7 on a stock motor. I would just let it shift. The power fall off after 5500 on a stock 91-95 is huge.

 

As for launching, it isn't hard. Powerbrake to the max....

 

Thats funny....according to the dyno chart I have here....it should be higher than 6k.

 

3.4L%20DOHC%205%20speed%20dyno.jpg

 

Granted, that is a 3.4L DOHC with a Getrag 284 in a Feiro......but other than that, it was stock. If anyone has a stock automatic dyno chart, post it!

 

Now the gearing for the 4T60-E is.....

 

1st : 2.921

2nd : 1.568

3rd : 1.000

4th : 0.705

 

Remember....you want power at the top of the current gear to be the same as the power at the bottom of the next gear.

 

At 6k you have 150 whp.....the 1-shift has a drop of 54% (1.568/2.921). So off of a 6k 1-2 shift, the tach drops down to 3200 rpm. According to the dyno chart I posted, you've only got 95 whp. Not near high enough I'd say.

 

I'd actually shift at 7k.......You've got 135 whp with a drop too 3800 rpm...which is also *about* 135 whp.

 

Now the 2-3 shift has a drop of only 64%...so you don't have to shift as high. For a 6700 rpm shift it looks like you have 148 whp.....with a drop to 4300 rpm....which makes nearly the same power.

 

3-4 has a drop of 70.5%. I'd opt for 6500 rpm....you do the math.

 

So my shift points for an automatic would be....

 

1-2...7000

2-3...6700

3-4...6500

 

....but thats using a manual LQ1 dyno chart and not accounting for the slur of the torque converter. I also wasn't as exact as I could of been reading the dyno chart.

 

Now, all that said...can you even shift a automaitc LQ1 at those speeds?

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Well we need to know what the vin # is of the engine he used, to know if it was a manual or automatic motor. That can make a big difference. Also he had a K&N style warm air intkae, which also helps make power after 6000. I know it sound,s and he goes on and says it makes no difference, but anything to help the 3.4L breathe helps on the top side. So IMO his motor is also pulling a bit stronger after max power around 5500 rpm. I've never driven or been in a stock 3.4L that doesn't fall off bigtime after 5500, and his holds to 6. Not calling bullshit, but his seemed to perform well. Also an automatic is going to make less power (drivetrain loss) than a 5-speed throughout the board.

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Yep....an automatic will consume more power.....but it should be even accross the board. Like I said, if you have a dyno chart for a stock or nearly stock automatic LQ1, post it.

 

What are the maximum shift speeds for an auto LQ1?

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Well mine pulls right to 7, with minimal power dropoff. Although I have no dyno, my max power is made at about 6, and it holds it to 7. So I shift at 7200 outta 1st, 7200 out of 2nd, 7000 out of 3rd, and I normaly stop racing by redline in 4th, but I will shift out of that at 7 as well.

 

The 7200 is indicated, although I have a rev limiter at 7150, but I shift right before the rev limiter. By years of knowing/racing the car, I know exactly where the limiter comes in at.

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I just talked to my roomate (BIGBULS).............

 

Seems he DOES have a bit of logic for the shiftpoints etc. that he came up with.......

 

http://www.w-body.com/forum/viewtopic.php?t=17672&postdays=0&postorder=asc&start=45

 

He has a nice writeup of an ideal shiftpoint selection for an LQ1 auto (starting the 2nd post down on the page).

 

Turns out HE had a link for a stock LQ1 auto (a 95 in this case), AND used a video of somebody's Grand Prix auto to account for torque convertor slipage and TC lockup strategies...........

 

Funny thing is........even though it turns out that my post a liitle earlier in this thread was a little flawed (I didn't take into account a few variables), the shiftpoints I came up with ARE pretty close to optimal.

 

Weird :)

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