So I'm planning on engine swapping my 84 C4. I want to have between 300-400 HP, but I also want to keep the same gas mileage if not a bit better. Anybody know some good recommendations, need one that can bolt into the stock transmission.
Price range is about 4000-6500.

 

Easiest is to get a later car with a LT1...

 

An LS swap could be pulled off with that budget with room to spare if you do the work yourself. The LS is just about a drop in replacement, it gets good fuel economy and is cheaper to make NA horsepower on.
You didn't mention what trans but, the autos will need a 0.4" flex plate spacer to work with the 700r4, the 4+3 will need an LS1 clutch and flywheel, BBC bellhousing, and a hydraulic throw out bearing or a custom mount for the stock slave.

 

I second the LS swap. Is the car an auto or a standard? If it's an auto don't waste your time using the 700r4. Get a 2wd 4L60e with the motor you want. If your goal is 300-400 hp then all you need is literally any LS. Even a 4.8L can make that power easily if you get a gen IV with the 799 heads already on it. Then all you need is a mild cam, an LS6 intake and you'r there. A 5.3L or a 6.0L will obviously make more.

You could LS swap and 4l60e swap (If it's an auto) for half of your budget. Take the extra money and get a nice stall converter.

 

Get a vortec 350 and convert your cfi over to tbi. You'd be pretty close to 300 I'd guess.

 

Thank you this helped a lot, and yes its an auto. The first thing I did when I got the car was rebuild the trans and put a bigger torque converter on it, but I'll look into what you recommended.

 

Not sure. Rebuilt to what? Stock rebuild might not hold. As to the TC, you might still have to change it to suit the system you created.

 

If you actually rebuilt the '84 700R4 you want to review everything that you've done. Many internal 'hard-parts' - input spline counts and many things about 'most' '84 700R4 are certainly 'non desirables'!

 

Actually, you should have put a smaller torque converter in it.

 

Rebuilding it to a 383 stroker would get you where you want to be HP wise. Budget would depend on the shop you use for the work

 

And install if he can't do it himself and maybe a torque converter if it isn't suitable and a rear end to handle the power. My rear end (ring gear) broke with the 383 and street tires. Other people have had luck running it.

 

I completed a Performance GM Crate Engine, Fast Burn ZZ4 w Hot Cam and Several LSX engine transplants

I love the ZZ4 crate engine. Great engine, warranty, good fuel econ if you keep your Foot under control.. I had a new 4+3 and rebuild the OD, rebuit the Dana 44 to 3:73 gears, great combo. Utilizing a TPI is a great idea. I'm goign to remove the TPI from my C4 Convert and install a LS3 ECM and wiring harness. My Z4 has the never timing cover and I can swap in a GM timing cover for the Crank sensor. And EFI Connection has the 24 or 56 tooth gear for the crank, and a host of any parts one might need.

LSX, ,... It is NOT a simple upgrade swap !! One needs to be a competent DIY person with patience, and friends to assist. However it's Well Worth the effort !! There's posts on Guys who have completed this swap and love he LS engine, rec that you Read them in entirety.. Installing a 4+3 behind a LSX, the OD will not live long. Best I can recommend ist hat you find a Donor Car, a total w a 6 Speed. The Tremic 6 Speed is a magnificent trans ! With a Donor you have at hand the wiring harness and many parts that you'l require. Sice the C4's have a Fuel Return line to the Fuel Tank USE IT. IT keeps the injectors and fuel pump Cool and Happy. You'll need to deal wit theTrans mount, but you'll find out about everything in current posts.

I completed a LSX swap w Tremic 6 Speed. ZO6 clutch kit (retained the GM hydraulic Clutch Release), a 9 inch,, etc etc. in my '56 Chevy 210 back in 2007. The very best thing that I've ever done to my old '56 Betty. I bought the engine, trans, wiring, bucket of misc stuff from a close friend of mine, less than 2k miles. His new Fire Bird WS6 Trans Am was sideswiped and totaled. But you'll need to rebuild your Diffy down to a 3:50 .great ratio. Depends a bit on Tire Height. My '56 has 3.50 and my C5 Corvette has 3.42's but a slightly taller tire size.

To this day the only thing I've done to this running gear in my '56 is to change fluids and replace the GM "Seeping" oil psi gauge Twice. The running gear is still clean, no leaks, no tune ups, no repairs and great economy - Except on those Spirited Drives.. The Torque is absolutely amazing.

good luck

Michael...

 

I swapped a LS (LQ9) into my 85 C4 and used the 700R. I didn't need to use the spacer for that transmission. To be honest the early C4's are a piece a cake to swap to an LS engine. I did my car in about a week's time.

 

I can't say I agree with you here. I have built several small blocks over the years. I had a 383 and a basic 350 in my 84. The LS swap was the easiest thing I have ever put in. A junkyard motor with a cam swap is all you need to make 400 hp at the crank. You don't have to bolt on heads or put in pistons. You don't have to plan anything. Just swap a cam and springs. And run the show with a good aftermarket controller like a Holley. It becomes drop in at that point. I felt it was much easier to get the power I wanted with way less work.

You will of course have to upgrade the fuel system with any motor that is making that kind of power.

 

That's odd, the LQ9 did not have a long crank variant only the LQ4s did, did you use a 4l80 or swap flex plate? If you didn't it would be darn near impossible to properly register the converter into the pump without a massive amount of shims.

I'm with Phobos on this one, the motor with swap plates drops right in, and you can either pay for or convert a stock harness into a 4-wire harness using the information at lt1swap.com. The only time it becomes difficult to make power on an LS is when it comes down to forced induction and space in the C4. As for the OD argument, I'll be testing that out on my 85, with a cam and springs you're looking at stock TPI torque and just under double the horsepower, but that's irrelevant to the conversation, OP has a 700R4.

 

84 4+3 has a great point. Is the car special to you? Are you wanting to do the engine swap as a challenge? If all you want is a faster car, if your 84 CFI is in great shape, you may be able to sell that classic for about the price of a ‘95 or ‘96.

Certainly, if you got decent money for your 84 plus the 6k you are willing to spend on the engine swap, a very nice late C4, hell maybe a high mileage ZR1 may be in your budget. There’s your HP.

Just stepping back a little on your question. The project does sound interesting though.

 

How much is an 84 worth again? How much do you think a higher mileage ZR1 goes for? Not sure it will take 6k more. I suspect higher.

 

Forum member VinnieP is asking 12 for his very nice 84. There is a 90 ZR1 for sale on this forum for 22 asking. (I was offered a ZR1 needing engine work with a salvage title for less than 10k a while back.)

His 84 would need to be very very nice and the ZR1 would not be a show car, but even on this forum there are two within 3500 using the OP’s motor budget figure. (12K+6500=18,500 - 22K = $3500.)

Just food for thought. That is all I was bringing up for the OP.

 

Yes this C4 is very specials to me, my dream was to own a C4 between 84-89. I want to build it for track days and every day use as it is my daily driver. The car runs perfect and there is no rush into this project just wondering what I should use for the future. Currently in the prosses of redoing the interior

 

In doing some research for my car, I have come across some stunningly powerful N/A LS's...

OVER 600 rwhp (!!!) from heads/cam/intake/header LS7's!!!

Who would have imagined a streetable, well behaved small block sized motor could do that?