Yes, it'll fit (almost everything is interchangeable) but, on a 5.7 it is not as efficient as it is on a 6.1. Some time ago one of the Automotive magazines (I think Hot Rod or Mopar Muscle) did a test using the 5.7 automobile, the 5.7 truck, the 6.1 and Edlebrock 4bbl. carb manifold, and on the 5.7 the one that comes on the Charger, 300C, Magnum and our Jeeps gives the best all around performance. If you're going to put the 6.1 heads on it, they'll fit too, but again won't work as well as the 5.7's do on a stock/relatively stock 5.7. If you go to a larger displacement, then you'll be in good shape though.

If you do something like this you'll need to put the 6.1 headers on it, and some sort of performance cam. You'd probably then want to ditch the 5.7 MDS valve lifters. You should also raise the compression ratio, as the combustion chambers in the 6.1 are larger which lowers the compression ratio on the 5.7. Overall, unless you go big, you should stick with 5.7 stuff and maybe think of doing some mods. to it. It's not too difficult to pull another 100-150 hp. out of a slightly modified 5.7.....see my mods. in my signature below. Right now I am about done and am running about 120 more hp. than stock and also now get 22-23 mpg on the highway.

 

Yes, it'll fit (almost everything is interchangeable) but, on a 5.7 it is not as efficient as it is on a 6.1. Some time ago one of the Automotive magazines (I think Hot Rod or Mopar Muscle) did a test using the 5.7 automobile, the 5.7 truck, the 6.1 and Edlebrock 4bbl. carb manifold, and on the 5.7 the one that comes on the Charger, 300C, Magnum and our Jeeps gives the best all around performance. If you're going to put the 6.1 heads on it, they'll fit too, but again won't work as well as the 5.7's do on a stock/relatively stock 5.7. If you go to a larger displacement, then you'll be in good shape though.

If you do something like this you'll need to put the 6.1 headers on it, and some sort of performance cam. You'd probably then want to ditch the 5.7 MDS valve lifters. You should also raise the compression ratio, as the combustion chambers in the 6.1 are larger which lowers the compression ratio on the 5.7. Overall, unless you go big, you should stick with 5.7 stuff and maybe think of doing some mods. to it. It's not too difficult to pull another 100-150 hp. out of a slightly modified 5.7.....see my mods. in my signature below. Right now I am about done and am running about 120 more hp. than stock and also now get 22-23 mpg on the highway.

thanks man seems like a lot of work haha, i just like the look of the intake manifold

 

I thought I'd elaborate a little on this 6.1 to 5.7 parts switching. On the intake manifold, you'd have a pretty good mismatch in port size and, to make it work as good as it could, you'd have to port match the 5.7 intake ports in the heads. Since the 6.1 ports are bigger, you'd have some 90* obstructions when the airflow hits the smaller 5.7 ports. Taper matching would probably work, but you'd have to remove the heads to do this properly. You also have to deal with the EGR issue....the 6.1 doesn't have one so there is no opening in the 6.1 intake to accept the tube going from the 5.7 EGR Valve to the intake. This would be a biggie if you're in an area that has an active "smog nazi" program with periodic inspections. Also, the 100% airflow maximum (volumetric efficiency) of the stock 5.7 is significantly smaller than the stock 6.1, so any airflow though the intake would be slowed down instead of hopefully accelerating it.

On the cylinder heads, pretty much the same airflow issues would come into play. The 6.1's bigger ports, valves and slightly smaller combustion chamber volume would, with an otherwise stock 5.7 could probably cause you to lose power, instead of increase it. There is a guy on one of the HPTuners forum that has done all this and more, and is not happy the way his stock compression ratio 5.7 works. He did 6.1 heads, intake manifold, overcammed it (longer duration with too much overlap which blows some of the compression out the exhaust) and then stuck headers with 1 7/8 in. primaries (too big for a stock 5.7) on them. He's done almost everything he could wrong, but everything right if he had hung all this stuff on a somewhat larger displacement short block. To give you an idea on the 5.7 cylinder heads, Hot Rod Network did a test with stock 5.7 heads and mild cam (almost identical specs. as mine), then with ported/polished and same cam, and finally, the same ported heads with a larger (6.1) displacement and a more radical cam. Here's the reference to the article....pretty amazing differences, EXCEPT when going from the stock heads to the ported heads....only 12 hp. increase. That's why I milled .030 in. off my heads to increase the compression ratio about a half point.
http://www.hotrod.com/articles/hemi-head-test-mild-and-wild/ What this shows is that the stock heads on the 5.7 are, pretty much, more than adequate for the displacement. In our (WK) case, the biggest choke point adversely affecting VE and performance is the crappy exhaust logs.

 

I have a 6.1 with 5.7 heads. I would like to put a Speedmaster injection manifold on. If i port match and mill the heads .030 would this work?

 

Welcome to the forum.

Huh? How did you end up with a 6.1 with 5.7 heads, unless you've picked up a short block or did a bore/stroke job on a 5.7? To answer your questions, yes, anytime you change the intake and/or exhaust setup, for best results you should port match everything. On my 5.7 setup with ported/milled heads, I port matched the exhaust ports to the ARH long tube headers, but not the intakes. I didn't match the intake manifold ports to the new intake port size because I didn't want to possibly contaminate the intake manifold plenum with plastic debris and the ports are smaller on the manifold so there won't be any restriction/blockage of airflow like there would be if it were the other way around. I also port matched (by tapering) the throttle body area of the intake so it would match the 90 mm throttle body I use.

My ported/milled heads are "supposedly" good for up to 650 hp. and will work much better on a larger displacement engine (like yours) than they do on the 5.7. The stock 5.7 heads are good for a slightly modified 5.7 engine but, on mine with both porting and milling, I figure I've only picked up between 20-25 hp.....maybe a dozen or so from each modification (porting/milling) to the heads.

Hot Rod Network did a test with stock and ported 5.7 heads (no port matching was indicated) on a mildly modified 5.7 engine (mild cam and headers) and the ported heads picked up only 12 hp. over the stock heads. They then put the same stock 5.7 heads on a 6.1 with the headers and a more radical cam and picked up 41 hp. FYI, the mild 5.7 with stock heads, mild cam and headers pulled 401 hp., the mild 5.7 with the ported heads pulled 413 hp. and the 6.1 with a bigger cam and the stock 5.7 heads pulled 486 hp. With the ported 5.7 heads on the 6.1, the horsepower jumped to 527 hp. Not too shabby, IMO. Some day I may do this, except I'd probably go with an MDS equipped 392 or 410.

I don't know anything about your Speedmaster injection manifold. What is it, type of injection used, size engine designed for, etc.?

On yours, I say, GOOOO for it!!