I bet you where thinking someone was looking for help on how to do it.

I'm looking for people that have done it and drive it daily or atleast quite frequently.

What sort of gas mileage are you getting with the swap?

Was the swap worth it going with say the supercharged 3400? For the amount of work and fab involved would have been better to just build the stock motor and boost it?

I have a ld9 that I will turboing shortly but have always wanted to do the swap but not sure if the extra weight was worth it or not.

Thanks for the info.

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

Well I'll tell you what. With the stock injectors maxed out on the 3400 you get 14mpg highway. The 3400 doesn't come supercharged, so you must be thinking about the 3800? The 3800 s/c I would say depends. Having the iron heads will make it heavier but there's a TON of aftermarket for it to suck more power out of it.

I'd say that if you're a fan of anything that involves driving the car hard around corners and such, that you're probably best off going with the boosted 2.4. I've noticed that my V6 seems to throw the handling some. However during normal driving you'd not notice it there til you put the pedal to the floor.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

I will agree with SHOoff. The handling around sharp corners you can feel the rear of the car get loose. I quit a bit more then with the stock 2.4 in it. A friend of mine has a 2.4 with a turbo on it. From a rolling 30 start its a head to head run with him sometimes pullin a little ahead but not much. From a dig I can pull up to 2 or 3 car lengths on him and keep it. Gas MPG is not good at all. But I didnt build the car for gas milage. If you do the swap you might want to look into a Megasquirt 2 or 3 ECM. Recently installed a 75 shot of N2O. With street tires best time was 13.784 in the 1/4 mile. Hopefully this helps.

I love my swap. Gas mileage is not good with the swap but its very unique and people ask a lot of questions when they see it. I built mine heads, cam, ported upper and lower intake and all solid tranny and motor mounts. I'm running an average 14.3 in a 1/4 mile on street tires with my centerforce clutch slippin and still the engine has more potential and more mods to come, Grand Am turbo kit, 3800 sc injectors just to name a couple. But you're probably better off to boost that ld9 and can make just as much power for cheaper than a 3400 swap without the headache of wiring, tuning, trans swap, guages, A/C, cruise and getting those things to work. I just wanted something different.


C:\Users\Phillip\Pictures

the swap was worth it in my car but i did do it just as a toy a the 3800 is a torque monster but i will say if i could do it all over i would do a 3400 i just put one in my step dads 89 z24 with a t25 turbo and it will smoke my car from a roll but from a stop i have more traction

its def worth it and fun. my 3500 swap drives just like wen it was still a ld9 until i punch it. theres def way more power and have a ton of fun with it as my daily. gas milage well thats another story. mostly bad due to a bad tune wich has me running rich all the time.

How about getting through emission testing? Here in AZ all they do on 95+ OBD2 cars is plug thier machine into the OBD2 port and read the computer. Is that still possible after the swap?

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

DSMskyline wrote:How about getting through emission testing? Here in AZ all they do on 95+ OBD2 cars is plug thier machine into the OBD2 port and read the computer. Is that still possible after the swap?

AFAIK, most states that require the actual scan are only looking for error codes (to make sure you don't pass inspection by disabling the actual check engine light). However, you'll have to check your local laws about it. Talk to someone who does inspections and ask what they look for.

RockinRay wrote:I will agree with SHOoff. The handling around sharp corners you can feel the rear of the car get loose. I quit a bit more then with the stock 2.4 in it. A friend of mine has a 2.4 with a turbo on it. From a rolling 30 start its a head to head run with him sometimes pullin a little ahead but not much. From a dig I can pull up to 2 or 3 car lengths on him and keep it. Gas MPG is not good at all. But I didnt build the car for gas milage. If you do the swap you might want to look into a Megasquirt 2 or 3 ECM. Recently installed a 75 shot of N2O. With street tires best time was 13.784 in the 1/4 mile. Hopefully this helps.

Ray, what are you running for a tune on that? If you got ahold of a tune from me or someone on here it most likely was something that came around from my car, and will eat tons of gas because there's a whole ton of room to cut it back. I got 14mpg because my AFR was coming out to 10.5:1 @ WOT and likely lower at less throttle. I turned it back and noticed a difference right away in MPG. Can't tell for sure what I do get now though, because I rarely drive the car.

DSMskyline wrote:How about getting through emission testing? Here in AZ all they do on 95+ OBD2 cars is plug thier machine into the OBD2 port and read the computer. Is that still possible after the swap?

On that you'll definately wanna run the N-body PCM for your swap. Megasquirt would give you and instant fail as it doesn't tie into that port at all. I don't have E-testing here, so I don't need to worry about it.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

Etesting, just use a stock(ish) tune... it took me 3 tries before I passed, but my 3800 isn't exactly stock.

For a 3400 5spd gas mileage estimate, give me til the end of the week then I'll fill up and give some official numbers. I could go mileage vs. gas gauge, but from full it made it to 3/4 at 135 miles and to 1/2 at 195 miles. So we'll see what it comes out to.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

Wow my gas gauge is messed up.

Anyways, the official results:

At 265 miles I had to put in 11.480 gallons to fill it back up. That comes out to about 23.1 MPG I'd say my MPG should show close to what average is. Most is driving to/from work, which is a lot of 55mph in the country with some stop signs and traffic lights here and there.

EPA rating for the car STOCK is 22 city, 33 highway, 26 avg. And the 99 Grand Am GT is rated at 20mpg average (which is where the motor came from) So I guess 23 isn't too terribly bad.

Though, I must note. It's not like I was driving the car really nice to get this number. The beauty of driving a 3400 J-body is the acceleration. So a lot was probably wasted there. That and if I didn't feel the need to pass everyone on the road on the way home from work. And with some tuning adjustments (if I could find my damn USB-Serial converter) I'm sure I could get the number higher. But 23 average isn't too bad I suppose.

No i'm curious as to what the guys with factory PCM's (i'm on Megasquirt-II) are getting for MPG.




i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

I am running a n-body pcm in my swap, but the miles don't turn over so I can't get a guess as to how many mpg I get. Are you piggy backed to tun the gauges sho off?


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

I have MS-II and a factory J-body PCM to run the gauges.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

I only use the stock computer for my speedo, but since the cav doesn't plan on being legal anymore I don't even need that, just four wheels and an engine.


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

Heh. There MAY be some illegal things about my car. Not limited to, lack of emissions controls. Removed safety features (air bags and headrests for example). And a disabled check engine light.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

LOL. Well the bad news for today is that when I got in the car so I could move it to get my truck out. I came to find out that I've waxed another starter, good thing I got a lifetime warranty starter last time.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

SHOoff Im not sure where the Megasquirt tune was pulled from. I didnt tune the car. Had a friend of a friend do the tune. The car is a gas monster. Only thing I done to his tune is retard the ignition around the WOT positions for N2O. If you have any suggestion or info it would be greatly appreciated. Right now the car is in the garage. Im going through the front end. The sub-frame has pulled away from the car in spots.

another starter eh jason what is the issue with your car and starters??



JBO since July 30, 2001

My 2.2 ate starters, the 3100 is still using the starter that came with it.


- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs

NOTa2_4 wrote:another starter eh jason what is the issue with your car and starters??

I don't know what the problem is. EVERY time it's the solenoid. It'll engage the flywheel for a split second then drop back. It's also associated with a bunch of grease that's on the inside of the starter, almost like it's blowing out a seal and losing everything from a bearing. Almost looks like antisieze on this one (still had all the stickers on it from when I bought this one).

It doesn't sound like it's staying engaged to the flywheel or anything because you can hear after I let go of the key. The thing does crank for a bit, as I need to adjust some issues with startup fueling in the MS. All the heatshields are on the exhaust manifolds. Perhaps I should try the bigger radiator, I see a lot of my fins are bent up good on mine along with the fact that it's got 160,000 on it. But the thing isn't overheating, so I have no idea.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

Thanks for all the info so far guys. Looks like I will be building 2 cars now.... my build LD9 and a v6 sedan...

Everyone that has done the swap seems to have used the 3x00 sfi motors, has anyone used a DOHC? Is there a reson no one has?

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

The OHV is pretty much a drop in due to the way the mounting works on it. With the DOHC there is a different mounting system, and the heads are wider making it a lot tighter fit. Probably why it's not been done. However I think I do remember seeing a picture of 1 car with it done. Looked really cool, but on helluva tight fit.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick

Makes sense. I saw a fiero with a 3x00 dohc swapped in with a single turbo making 430 whp. That would be pretty sweet in a j.

"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"

its not really a 3x00 dohc swap on a fiero its accually not ever called a 3400 its just 3.4 DOHC you don't call the 2.4 a 2400



JBO since July 30, 2001