Asked by Mar 16, 2009 at 03:51 PM about the 1991 Chevrolet Camaro

Question type: Car Customization

I came up with a crazy off the wall idea. I am thinking about putting a 5.7 HEMI in my camaro. I dont think this swap has ever been done before. What do you guys think? The only problems i can think of are the motor and transmission mounts and possibly the radiator. This is an idea ive been considering for awhile and im just now acting on it. Any suggestions or ideas are cool, or if you want you can tell me im just plain dumb, but thats what hot roddings about. Who wouldnt want an easy 420 HP with a stock cam?

32 Answers


I really wish i could help you with this one. But, given my history on hemi's (none at all) i cant say anything more then. I know your going to have to refab up some new Motor mounts and tranny mounts. As well as possibly a new front cross member. maybe even a tranny crossmember if its heavy enough. Also one of the most important factors to do is messure a hemi valve-cover to oilpan then head to head across the back and front, then front to rear. Then measure the engine bay in the camaro. Then if your getting a FI model make sure u can run the wires and mount the ECU somewhere safe, but thats not the hard part lol. The rear end should be fin i know u can put a Chrysler in a GM car no problem, but i would get a better chrysler to go with the power the open dif on the RS will go boom at some point. Overall you're in a for one hell of a job. I've seen alot of crazy things done in my life but this shouldnt be to difficult as long as u make sure its all going to fit and stay sound in the car.


Would be cheaper to just build a chevy motor and slap it in! What your gonna spend on the Hemi you can build way more powerful and cheaper chevy motor that will bolt right in. If you have lots of money to spend then sure it would be cool I have never seen it done before.


i can get a 5.7 hemi, transmission, ecm, and wiring harness for about $3500 not as pricey as you would think. I just thought it would be kinda cool to do something that hasn't been done yet. I know a lot of people will hate me for it though.


oh yeah, and 420hp in stock form.


Its not the cost of the engine, tranny, and wiring harness that you should be worried about, unless you plan on doing all the fabrication work to fab up engine mounts, transmission mounts, and modifying the cross member, that is going to be the real cost. Not to mention you will need to order a custom driveshaft, and you will have to stiffen up the body and frame. What I would be more concerned about would be Emissions Regulations. I now a few states that follow C.A.R.B. require that if you do an engine swap, the engine that goes into the vehicle be of the same make and vehicle category, and at least the same modle year or newer. With the '91 you may be safe, but before you do this I would check out the emission legislation in your state.


why not for for an lsx engine, lighter, likely cheaper, and still a chevy engine so i would imagine making it work would be quite a bit easier


its the custom driveshaft thats going to cause you the most problems i think. if youre good with a welder you could make your own mounts and such so thats not a big deal but the driveshaft will cost some extra money. and if you are going to go with a hemi go with the 6.1L instead of the 5.7L. ive got the 5.7L in my 300C and i love it but you can start out with a much better building block with the 6.1L. it puts out 425 hp stock anyways haha


the motor and transmission mounts are available aftermarket, so im not worried about that. i havent thought about the driveshaft yet. theres a place near me called universal products that specializes in custom driveshafts. and the 5.7 hemi actually dynoed out at 420hp with just headers


what 5.7L hemi are you talking about man? i have a 2005 model and it makes 345 hp. the 6.1L is the hemi that makes 420-425hp. unless its a built 5.7L it doesnt make 420hp.


it makes 345 rated horsepower. they are really underrated. on the dyno they will make 420 horsepower at the crank. i would guess that this is for insurance purposes.


have you ever herd of break horse power i guess now


bhp on brand new hemi that just came out is 390. the 2005-2008 bhp = 345


i don't know where you got your numbers but you're way off. they're rated a 345hp, but i've personally seen 3 different 5.7's on and engine dyno putting down only around 340bhp. don't forget this was on an ENGINE dyno, not a chassis dyno. so there was no drivetrain loss. the only HEMI out right now that makes anything over 400bhp stock is the 6.1. if you wanted to be at over 400bhp stock, just get an LS3 430bhp, and they have the best flowing heads of any of the LSx engines. cam only LS3's have been known to pick up nearly 70bhp. an LS1 only gains about 45-50bhp with a huge cam.


who would want an engine with an extremely weak powertrain. the piston rods can't even hold up in those engines.


are you talking about the hemi? that engine is amazing. what would you suggest?


In my experience, trans-brands engine swaps have never worked well. Too much hammer job, welding bases, cooling systems, transmission-rear gear never combine, electrical problems, engine accessories, exhaust, etc., etc., etc. After investing a lot of money, you'll have a car worth a lot less than when you started.


you could a 350 crate engine that already has about 450 horses after you put the intake and accessories on for cheaper than what you are talking about doing.


i never said the hemi swap was a good idea so i dont know what your saying im talking about doing. i just said the hemi is an awesome engine. and in these cars a crate motor isnt the best way to go. an ls series drivetrain conversion is probably the best bet


Mitchell Merritt has the right idea on this. The LSx swap into a thirdgen is very well documented and all the parts are available off the aftermarket shelves from places like Spohn Performance. You'll get better power with less fab-work and there are a lot of guys who have done similar swaps (mainly LS1 engines) that can help you get past the harder parts. Check out if you aren't familiar with it. A Hemi is the last thing I'd want to swap into anything. Maintenance on those engines is pricey (16 spark plugs makes for an expensive tune-up) and the powertrain issues you'll have aren't worth the power. Fitting the Hemi-car trans under thirdgen sheetmetal will be tricky, while you could use a factory '98-'02 T56 with the LS3 engine, and only make a single floorpan cut. You'll also have to rework the fuel system for the Hemi, and the factory instrumentation will be useless. Just my $.02.


i agree with you. ls series engines are the best option for the 3rd gen. find a wrecked gto with the ls2 and take that drivetrain. but just so you know if you do the spark plugs outrself which is very easy its not expensive at all. having a shop do it costs a lot though yes. i was quoted around $300.


I completely agree with the LS swap over the Hemi idea, although I think a better fit would be a Carburated 350. They are a great engine, and there are lots of parts available in the aftermarket. The best part is however that you won't bastardize what is a beautiful car. If you want Good Solid power that is fairly inexpensive (LS series engines and Harnesses are fairly expensive even used) GM Performance Parts ZZ4 engine or the 350HO Crate Engine from GM Performance Parts.


the LS swap is a good idea also.


i'm not goin to dog it or anything but i'm a chevy guy, only ford i own is my 88 1ton cuz i didn pay for anything one it since my buddys jus give me the parts to build it but thats besides the point. puttin a hemi in a chevy in my opinion is a waste, build a nice high output small block, i got a 350 punched out 60 thow over to 355 and i'm pushin jus over 550hp in my lil 63 acadian, way cheaper and u with have a really nice engine when u r done. cheers


In the name of preventing the spread of disinformation: If you bore a 350 block .060" you get just over 360cid, and thin cylinder walls. Not a 355. Just so you know.


The 350 isnt a bad idea, but i want to do something different than everybody else does. Nobody has a 3rd gen Camaro with a new hemi in it. The 420hp numbers are from Car Craft with no engine acessories, electric water pump, etc. Sorry about the confusion about that. The factory break horsepower numbers are done with all the engine accesories a/c, alternator, water pump, power steering, etc. That would make for huge parasitic loss in the motor.


I say-go for it!! be original!! I once,installed an olds rocket 455,out of a 71 cutlass,that was too far gone to restore--into an 88 Berlinetta v-6 camaro,,and(until the rear axle exploded) Had one heck of a fun toy!! I installed a ford 9 inch rear-end in it,and to this day--My ex-wife,in Irving Texas,is still driving it!! Good luck,and have fun doing it!!


if you dont think it has been done you are very wrong. i personally have a 1991 camaro rs with a 5.7 hemi, dont get to far ahead of your self mine has a shift kit in it and it is a very high maintenance car i have to go over every thing about 2 or 3 times a month it is a lot of fun and trust me it will burn rubber like no tomarrow BUT again it takes a lot of work AND a lot of mone to keep it running just right


why don't you get a grip and build your self a real 302 and it will blow any hemi don't be a fool man or all the work it's easier to build a new engine..think about that for a moment,or go back to smoking crack and think of another idea.Lamo


Good in theory, Not very cost effective, or practical, a Chevy engine would be the correct way to go .


another option over a newer ls from a car is the truck motors LQ4 and stuff. they are cast iron but pretty mush the same as the aluminum. a little cheaper but will do great with boost. also the f- body gto and others parts part on to the blocks.


I'd just build a chevy motor, get a Rebuilt 350 block and build it with the good stuff, Forged Crank, forged rods, forged pistons, Lunati Voodoo cam & lifter kit with an rpm range of 1400-5800, 1.6 roller rockers, vortec heads, 52mm throttle body, and upgrade to 32lb Injectors, a Magnaflow 3" cat-back exhaust topping it off with a k&n C.a.i. and thats enough to make well over 425hp, now as far as the rear end goes the RS had highway gears on it so naturally your going to want to swap them out for a nice 3.73 posi and upgrade the 10 bolt to an 8.5 ring and pinion if your on a budget, but if money is no object then find a ford 9" at a junkyard or buy a brand new Moser with 31 spline axles and you'll never break it.

5.7 Hemi is not a real Hemi 4 valve engine is not a Hemi

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