Georgia Fiero Club Forum
All Things Fiero => General Fiero Discussion => Topic started by: GTRS Fiero on March 15, 2017, 06:33:31 pm
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How does the 3800SC compare to the 4.9? Will the 3800SC keep up off the line, or just take over once moving?
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No one has driven both?
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I've never driven a 3800.
The 4.9 is a torque monster, though. I think it would get out of the hole quicker. But it's all done by 5K.
I can give you my admittedly biased opinion, but since that's not what you asked for, I will refrain. (You might be surprised.)
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Somewhere, I read that the poster thought their manual 3.4 was as fast as their 4.9 auto, off the line.
I thought RobsFieros. had done some 3800SC conversions. It seemed to me that the supercharger took a bit to kick in. A lag, if you will.
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Somewhere, I read that the poster thought their manual 3.4 was as fast as their 4.9 auto, off the line.
I thought RobsFieros. had done some 3800SC conversions. It seemed to me that the supercharger took a bit to kick in. A lag, if you will.
That was me. Sort of.
My 3.4 felt like it had as much power as the 4.9. Not as quick off the line, though. (Although I did make a Spec 2 clutch really unhappy, and shattered a Getrag.)
The 3.4 was mostly top end. It would wind to 6K, and keep pulling.
Hard to quantify, really. My apologies for the confusion.
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Sorry. My memory fails me...along with a lot of other things.
Hmmm. I thought the 3.4 ran out of steam about 4,500RPM.
My understanding with the 4.9 was that it was good until about 120MPH, but I've never been that fast with a 4.9. I drove one with a 4T60. It was quick, and pissed off the Corvettes, but I was afraid to get on it too hard, for fear of destroying the transmission.
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RobsFiero and Flyboy81 were working together and Derek did a built 3800SC for his Formula. That may be what you remember.
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Sorry. My memory fails me...along with a lot of other things.
Hmmm. I thought the 3.4 ran out of steam about 4,500RPM.
My understanding with the 4.9 was that it was good until about 120MPH, but I've never been that fast with a 4.9. I drove one with a 4T60. It was quick, and pissed off the Corvettes, but I was afraid to get on it too hard, for fear of destroying the transmission.
A 3.4 with a stock intake will be starting to get unhappy by ~5K.
I had a Trueleo intake, ported heads and lower intake, FOCOA headers, big injectors, and a Crane 272 cam. It was quite fast, but I spent way too much time and money to get there.
The stock 3500 in my G6 makes more power (220 HP), right out of the box, than that 3.4 ever thought about making.
The 4T60E is what came with the 4.9, in a car that was nearly 1000 lbs heavier than a Fiero. If it's in a good state of repair, you ain't gonna hurt it, by punching it, if the only difference is that the Fiero is wrapped around it instead of the Deville. You'll probably make a lot more noise, however. :D
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I don't know that I ever got my 2.8 up to 5K RPM. I hope I won't have to rev my 3.4 that high, either.
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I don't know that I ever got my 2.8 up to 5K RPM. I hope I won't have to rev my 3.5 that high, either.
Why not? If it's in a good state of repair, it's designed to run to 6K. GM wouldn't have put that 6K redline on the tach (or the 6200 RPM rev limiter, in the pre 88s) if it was detrimental to spin it that high. They were, after all, responsible for warranty repairs.
The lower end of a 3.4 (rods and crank) are essentially identical to the 3.4 DOHC. People spin those things to 7K all day long.
Once you get your car back, and sorted out, take it and put it on a dyno. Run it to 6K, at least once. (You won't hurt anything.) Watch where the power starts to drop off.
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Won't I feel it drop off on the highway?
Shouldn't it be driven easy for the first few thousand miles.
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Sure. Drive it easy until you're comfortable that it's broken in. I didn't mean to do it as soon as you got it home. Sorry.
You might or might not feel it fall off, on the highway. When my 3.4 was stock, it felt "pretty strong". Especially compared to the 2.8.
The dyno chart told another story. It started to fall off at around 5K. Maximum power was about 135 HP. (That was through an automatic trans.)
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I have to correct one misguided notion here, if I may.
Contrary to popular belief, you should NOT baby your new engine while breaking in. You should avoid going over 4k for a 1000mi or redlining it, but definitely punch it a few times to set the piston rings. Don't use cruise control and drive unsteady paces for the first 1k as well.
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Well, mine is SUPPOSED to get a 500-mile break-in, because I don't want to be that idiot on the highway who won't pick a speed, and I don't want problems driving 950 miles by myself.
Yes, I'll have some fun coming home (that's the plan, anyway), but I won't scream the engine, either.
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I had fun being that idiot (first time ever, i promise!) that couldn't pick a speed all the way from Augusta, ga to Memphis, Tn breaking in my last build. I was careful not to pace anyone and piss them off, but one slipped through the cracks and some guy driving a u haul was up for the challenge. Needless to say, he did me a favor. I got another chance to set my piston rings and have fun smoking an easy target, all while keeping it under 4k. Good times.
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I have to correct one misguided notion here, if I may.
Contrary to popular belief, you should NOT baby your new engine while breaking in.
I suppose I may have misspoken. I never meant that it should be babied. Just not "beaten upon".
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I don't see where you said to baby it. I didn't mean to call you out, Radar. I was commenting on the general direction of the line of questioning and just intended to steer the conversation a little. I hope nobody was offended. I've read so many opinions on the break in subject that I drew a general inference that:
1st start- 20 mins@minimum of 1500rpm to break in the top end. Drain and refill oil and filter
2nd start- run hard under load a few runs, but don't go over 4k, in order to set the rings
Break in- hard runs, no over 4k and varying speeds to properly break in cylinder walls, bearings, and finishing valve train break in.
If you maintain a steady speed, your bearings will have a flat spot, potential for egging.
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I created a new thread to keep this one on topic.
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The dyno chart told another story. It started to fall off at around 5K. Maximum power was about 135 HP. (That was through an automatic trans.)
Wait. HP at the wheels on your 3.4 was only 135? I thought you had 200 at the crank, with your mods. 65HP is a terrible driveline loss.