Just wondering if a 3.4 is worth the work.... what is the 1/4 mile time witha stock 3.4 DOHC??

and what would it be with a turbo up grade ?

high to mid 14's stock driving hard.

possibility of low 12's with a pretty serious build when turbo'd.

Some have gotten in the low 14's on stock DOHCs but a "safe" guess on a manual one is mid 14s.

My bone stock 3.4 DOHC swap into an 87 SE using a 5-speed getrag ran a 14.15et @ 98mph with a slipping clutch. The clutch was slipping during engagement that run because I tried to launch it at 4000 rpm and it didn't like it too much. Of course it was just a stock replacement clutch; nothing performance oriented.

-ryan

Don't let people here fool you. the 3.4 DOHC is a monster waiting to be unleashed. You also have to remember you can stretch out the gears a very long way compared to other engines because of the exceptionally high redline.

A turbo will net you huge HP out of this engine as well. There's a member on here that's over 400 at the wheel IIRC, and he has a stock bottom end. And before anyone says the 3.4 DOHC can't hold 400 ponies stock, there's a guy on here that's had a 350+ WHP 2.8l going for around 20k miles...

Problem is, they're big, heavy, and not just heavy but top-heavy.

If you really want a 60 degree you might try a 3900 instead!

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86GT Modded 3.4l V6/Getrag with Trueleo - 210WHP
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My 88 runs mid 14 on hot day last time I checked non turbo. What I like is the how it pulls all the way up the powerband. The fastest I have been is 120mph @ 4300rpm in 5th. Engine redlines at 7100. Car needs wings but I'm not trying out for mine at those speeds it's stupid unless you are on a track. I think the Getrag is at about it's limit with this engine in stock form as far as longevity. I'm using a stock clutch for the reason I figure it is less expensive to replace it than a getrag or transaxle.

I like the engine, I was not trying to convince you not to do it. I almost bought one about 2 years ago.

In my opinion the pros are: Sounds great, install is pretty simple, pulls hard to redline, great for adding a turbo
cons would be: timing belts, top heavy, and not a really impressive MPG engine

I believe I've heard of 3.4 TDC's cracking 13's with a stock engine in an optimized chassis (and driver mod).

Yeah, it is very heavy for its power output, but it has a wide powerband that goes much further toward making a faster car than the lower revving but equivalently powerful Caddy 4.9.

mine is a low 13 second car with the 4.10 four speed, custom intake and custom exhaust and in the 12s with a boost of nitrous

quote Originally posted by Erik: mine is a low 13 second car with the 4.10 four speed, custom intake and custom exhaust and in the 12s with a boost of nitrous

That is really impressive. If only the 4.10 had a 5th overdrive gear it would be the "perfect" transmission.

The 3.94 gearset for the 282 gets you pretty close. The 1.03 fourth will give a 282 car the advantage on top-end acceleration. You can keep the 0.72 fifth or go with the 0.81 fifth.

Hey DougE I tried calling you, have you changed your # Hit me up via PM with a contact ph

ME WANT 3.4L DOHC!!

Great thread. I had a chance to run mine down the track last month. I chickened out because if I broke something, I could not get home (over 100 miles away). I will do it maybe in the fall, and post the time/speed. I have a 05 GTO that has done 12.3/112 at the track, and I know im not even close to that. But I hope im in the 14's with it. My next motor will be a LS3.

Rob

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88 Coupe, CJB T-TOP, 1996 3.4 DOHC and a GT clip

If you evaluate the power band of the 3.4TDC engine; it makes most of its horsepower at the top end. Therefore we can assume that 1/4 mile times for this engine are heavily dependent on gear ratios. With a 2.94 FDR the engine is probably a slug but with a 3.90 or 4.10 FDR it's probably respectable. With a turbo and four valves per cylinder the power is probably awesome. I believe Matt Hawkins is the one making over 400 HP with this engine. The 492.5 lb weight is something that needs to be considered but the swap is basically a bolt in and rewire/reroute job.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: If you evaluate the power band of the 3.4TDC engine; it makes most of its horsepower at the top end. Therefore we can assume that 1/4 mile times for this engine are heavily dependent on gear ratios. With a 2.94 FDR the engine is probably a slug but with a 3.90 or 4.10 FDR it's probably respectable. With a turbo and four valves per cylinder the power is probably awesome. I believe Matt Hawkins is the one making over 400 HP with this engine. The 492.5 lb weight is something that needs to be considered but the swap is basically a bolt in and rewire/reroute job.

Dennis again I have to correct you about the weight of the DOHC. Have you weighed it? I have so I should know. ..it is 465 lbs dressed with the manual flywheel. VERY close in weight to the 3800SC

Aaron over on RFT has a 3.4 DOHC turbo and it aint no slouch 417whp/427wtq) I would expect it to run in the 11s

[This message has been edited by Erik (edited 06-05-2010).]

quote Originally posted by Erik: Aaron over on RFT has a 3.4 DOHC turbo and it aint no slouch 417whp/427wtq) I would expect it to run in the 11s

Aaron's car is not a great example. His car only made ~330whp on the dyno, but he is using the crazy 1.25 (+25%) correction factor for his high altitude to get the 417whp number. The generally accepted limit for using power correction factors accurately is +/- 7%.

quote Originally posted by RacerX11: Aaron's car is not a great example. His car only made ~330whp on the dyno, but he is using the crazy 1.25 (+25%) correction factor for his high altitude to get the 417whp number. The generally accepted limit for using power correction factors accurately is +/- 7%.

That is not as bad as you make it out to be. There is a 15% drive train loss. So 15% + altitude adjustment adding up to 25% total is only 3% more than the +/- 7% that you are concerned about. If we use just 7% added to the 15% driveline loss then his car still makes 402 hp at the flywheel.

Yes, but the post said whp, not flywheel hp. Still that's impressive.

I cannot comment on strip times. I don't agree with the MPG statement. I just got 25.679MPG. I was not driving for MPG either. When I do get to the strip I will post a slip. I honestly don't think I can pull the best time possible for my car. I keep shifting at the spedometer's redline, 5500RPM. I will probably need at least 2 or 3 passes to get a nice time.

quote Originally posted by dratts: Yes, but the post said whp, not flywheel hp. Still that's impressive.

I misread it then. There are supposed to be no adjustments for wheel hp. The whole point of wheel hp is that it is exactly what is being put down at the wheel.

quote Originally posted by Doug85GT: There is a 15% drive train loss.

No, there isn't. Not with a FWD stick.

quote Originally posted by Will: No, there isn't. Not with a FWD stick.

There is always drivetrain loss between the engine and the wheels. The question is always how much. 15% is a reasonable number for a FWD stick. It may be even higher given the fact that a stock 3.4 DOHC dynos ~175 whp but is rated at 210 hp. That is about a 17% drivetrain loss.

It's not 15%.

Do the swap. Dyno the car on a chassis dyno. Change from iron to aluminum flywheel. Re-dyno. What happened?
In the above scenario, you'll get different power gains in different gears and/or at different acceleration rates.

With my turbo I have run 11.9 @ 118. My best fuel economy has been 28 MPG on a highway run.

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62 Buick Special
86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo 415 WHP, 11.9 @ 118
88 Toyota Supra Turbo

quote Originally posted by Matt Hawkins: With my turbo I have run 11.9 @ 118. My best fuel economy has been 28 MPG on a highway run.

Very nice.

I ran the numbers for a 3100# car (with gas and driver) and your trap speed here and your hp and trap speeds come out perfect. ET is a little off but in the ball park. For these kinds of calculations ETs are never quite right because everyone shifts at different speeds and automatics shift faster than manuals.