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3.4L DOHC top speed


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Guest Anonymous
Posted

Does anyone know what the top speed is for a 3.4L DOHC (1995) is in a grand prix? I haven't taken it over 88, for fear of frying the car (its old). The speedometer goes to 115 but i heard a rumor about it being up towards 130. Whats the truth/fiction?

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Posted

The governor on auto trannied LQ1's cuts in the 117-122mph range at around 5400-5600rpm if you lock it into 3rd gear (which gives the fastest acceleration, as in "D" it shifts 3-4 at ~110mph/5200rpm).

 

If you bought a chip for it (FFP is working on an SFI LQ1 chip, and the major manufacturers already have them), it'd probably hit around 130ish (6K+rpm in 3rd) and simply run out of power...............either way, it will NOT pull 4th gear...........it just doesn't have the midrange power.

Posted

Also.............I should point out that 5 speed's generally cut a little higher than autos............121(mine)-125mph is the average (4200-4400rpm in 5th, or 6500-6750rpm in 4th), although I know of at least one that pulled to 129mph (actual.........the HUD said 125).

 

 

 

 

Either way, if you want to test it, go find a secluded, FLAT and long (3+ miles) road somewhere and take along a GPS for accuracy.............as I've said, the speedometers aren't all THAT accurate.

Posted

Yeah.............with 3.73 gears.

 

The stock 3.43's just put you too low in the powerband to go faster in 4th than in 3rd gear..............remember, 6500rpm in 3rd (about the end of the effective power curve on an LQ1) is only ~4600rpm in 4th (1:1 3rd gear vs 0.705:1 4th).............that's a BIG ratio gap.............and it's (6500rpm in 3rd/4600rpm in 4th) also right about 140mph.............and the LQ1 does NOT make enough power (even with bolt-ons) at 4600rpm (or 6500 for that matter) to pull any higher ..............in fact, it's going to be DAMN hard to even get THAT far.

 

Hell......even with 3.73's, 140mph in 4th gear is at or a little shy of 5K rpm...........and since even a full bolt-on LQ1 is NOT going to be making more than 175-180whp at that rpm (5K), I just don't see the car getting too much further...........

Guest Anonymous
Posted

I've considered all the engine upgrades and such, but my 3.4 has enough power for what I need it for (running around town), and its not worth sinking a shitload of money into an older car. Im scraping up pennies for a GTX i found nearby.

Posted
I've considered all the engine upgrades and such, but my 3.4 has enough power for what I need it for (running around town), and its not worth sinking a shitload of money into an older car. Im scraping up pennies for a GTX i found nearby.

 

Grand Prix "GTX" or a Plymouth GTX? :wink:

Guest Anonymous
Posted

grand prix, of course, but I don't have the cash for one now...

unless someone wants to conviently hit my 95 GP and insurance could cover me :D

Posted
Yeah.............with 3.73 gears.

 

The stock 3.43's just put you too low in the powerband to go faster in 4th than in 3rd gear..............remember, 6500rpm (about the end of the effective power curve on an LQ1) is only ~4600rpm in 4th.............that's a BIG ratio gap.............and it's (6500rpm in 3rd/4600rpm in 4th) also right about 140mph.............and the LQ1 does NOT make enough power (even with bolt-ons) at 4600rpm (or 6500 for that matter) to pull any higher ..............in fact, it's going to be DAMN hard to even get THAT far.

 

Hell......even with 3.73's, 140mph in 4th gear is at or a little shy of 5K rpm...........and since even a full bolt-on LQ1 is NOT going to be making more than 175-180whp at that rpm (5K), I just don't see the car getting too much further...........

 

get NAWZ!!!!!!!!!!!!!!!!!

Posted

I'd get that 3.4 checked out, my old 91 GP 3.4 could slam the limiter in 4th all day long. My Z34 will also hit the limiter in 5th pretty decent too. Both limit at 125.

Posted

the auto-trans limitor as set on the chip in at least two stock programs (AYSZ and BHAK) is set to 120mph, I've hit my speed limiter many times.

 

--Dave.

Posted
I hit 139mph in 3rd on the dyno.... it's roughly 6800 rpms. 8)

 

YOU sir, have a slipping torque convertor (a little at least)................139mph in 3rd should be around 6500rpm on a healthy 4T60-E (with normal amounts of WOT slip).

Posted
I'd get that 3.4 checked out, my old 91 GP 3.4 could slam the limiter in 4th all day long. My Z34 will also hit the limiter in 5th pretty decent too. Both limit at 125.

 

And YOU should remember that we are talking about auto trannied cars (the GPGT owned by the thread originator is an auto [it's a 95]).............as I have already posted, manuals WILL hit their governor at high rpm in 4th (6500+), or much lower rpm in 5th (4200-4300 on average).

 

 

 

Oh.....in case anybody was wondering...........while even a chipped LQ1 auto will struggle past 130mph, the manuals should have no problem getting past 135mph.............they have a more efficient tranny, and better gearing (to access more of their power at top speed).

 

And that's stock............modded, 145mph in 5th gear (~4900rpm with 225/60R16 tires, or ~5100rpm with 245/50R16's) should be quite doable.

Posted

Oh...........in case any of you 3.1L MFI guys (those with chips) were wondering...........

 

A 3.33 geared 4T60/4T60-E 3.1L MFI will NOT get much past 120mph on flat land unless it's modded..............even then, getting past the 130 barrier is going to be virtually impossible without different gearing, forced induction, or some solid internal work to the engine (or a tailwind or downgrade :D).

 

They just don't have the power to overcome the aerodynamic drag.

Guest Anonymous
Posted

Play nice now... :)

 

There is nowhere near me that I could even take my car to hit 120 or 130, its all curvy back roads up here in the sticks if NY, unless I had a death wish.

 

I could take it on the highway, but theres a ton of traffic and its swarping with cops

Posted

i'm not talking bolt on mods, u ever been in a 3.4 car with a new motor running 10.5:1 compression? how about ported heads and some cam timing? and when u used to go that fast i would take 3rd gear to about 7100 cause it would pull all the way, then i would start out in 4th right about 5700 if i remeber correctly. trust me a modded auto 3.4 can pull 4th no problem. wanna hear something cool. when my motor was first broke in me and 5SPEEDZ34 took it out for a ride. he was like it doesn't feel that fast, then we went in his 5 speed. my auto could wind out gears faster than his 5 speed. lol

Posted
YOU sir, have a slipping torque convertor (a little at least)................139mph in 3rd should be around 6500rpm on a healthy 4T60-E (with normal amounts of WOT slip).

:roll: Wow, it must slip like crazy if there is 300 rpm difference! :roll: :lol:

Posted
i'm not talking bolt on mods, u ever been in a 3.4 car with a new motor running 10.5:1 compression? how about ported heads and some cam timing? and when u used to go that fast i would take 3rd gear to about 7100 cause it would pull all the way, then i would start out in 4th right about 5700 if i remeber correctly. trust me a modded auto 3.4 can pull 4th no problem. wanna hear something cool. when my motor was first broke in me and 5SPEEDZ34 took it out for a ride. he was like it doesn't feel that fast, then we went in his 5 speed. my auto could wind out gears faster than his 5 speed. lol

 

Wow, im learning more and more about my car every day... Josh, is the cam timing mod still on there, or am i gonna have to do that?

Posted
no, its not on there its stock. but its easy to do

 

Hmmm... If your coming to the kensington meet, bring the tools, and i'll bring anything else we'll need to do it. I'll have some tools in my trunk.

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