I'm just throwing ideas around but how does a 383 compare to a 427 as far as power delivery and power output are concerned? Is the extra $5k or so for the 427 worth it? A very broad question I know but had to ask.

Thanks,
Joe

 

uneducated opinion: 427 > 383 :D

 

Before you get into the value question how do you plan to use the motor? Street, drag or road racing? Do you plan to stay with a small bore block or go with a C5R to build the 427?? The 427 made from a large bore block is a kick-butt motor no doubt, and should be reliable in endurance road racing. If you plan to get to a 427 from stroking a small bore block I (and many engine builders who's opinions I respect) say you would not get the reliability you might want to road race the car. Even a 396 is beyond the curve for endurance applications. Street and an occassional trip to the drag strip and you could be fine going to a 427 from a small bosre, personally I wouldn't do it.

Just my .02, no flames please.

Les

 

The car will be primarily a street car with ocassional drag races here and there and likely never roadracing although sometimes my street driving can qualify as road racing ;)

I was thinking the resleeve of the small block for the 427 and I am with you it makes me nervous. I resleeved my racebike before and it was never right. Maybe things have gotten better though........

If I go with a C5r block then that bumps the price up for the 427 another $5k :eek:

Joe


[Modified by CRUZMISL, 12:07 AM 12/14/2003]

 

Until available head/intake combos flow better, the major difference will be 30-50 lb.-ft. of RWT. As the displacement rises, the ability of the LS6 head and intake to breathe above 6k becomes the limiting factor. You'll certainly feel the torque difference, and street traction in first and second (MN6) will be close to nonexistent.

Good, clean fun.

 

I cannot answer your question - beyond my scope. BUT, I was at MTI yesterday with a few friends. Some of my good friends have had a lot of work done by MTI, and we have gotten to know Jayson (the owner) pretty well.

He set up a demo for us yesterday to show us his new boring machine, and the "427" sleeves he uses. You'd have to see his new boring machine to appreciate it. Jayson has spend MAJOR dollars for this machine. It is really state of the art for an aftermarket engine buildler. And the sleeves are really something as well.

Jayson really knows his stuff. And what really impresses me is his approach. He believes in building engines that are proven, and he doesn't like to stray from a proven package because he offers the packages with a two year warranty. His 427 package on a MN6 car puts out right at 500 rwhp - with the warranty!

I'd contact him to answer your questions.

 

I needed to make that choice as well before I went with the Lunati 382 stroker kit :yesnod: There is something to say for reliablility and all matching forged parts which work together. The Lunati package has been a very good choice for me...the street manners have been excellent and the the strip performance is there!!..Of course, no matter which way you go ALOT will have to do with the PCM tuning . It will need to be just right :smash:..it may take a couple of trips back to the tuner and LS1 Edit for the best end result program..

Find a tuner you trust ..that has done this before and has a warranty on the work..You only want to do this once..Get it right the FIRST time.. :chevy

 

Good post, good advise. BTW in my case I went with a matched Callies rotating assembly, a little cheaper than Lunati (which I ran in my other race car) but every bit as good.

I hold to my recommendation about a 427 (and resleeve), I know of at least one person who has had problems with two of those motors and gave up - that was enough for me, especially with input from two well known engine builders in my area (Garry Grimes and Lamar Walden).

If you want a bit more than you can get from a 383 conside a 408 iron block, my builder makes a killer one - Lamar Walden, 770 855 7141.

The comment about tuning is key, it will take several trips to a good tuner to get it dialed in. I have road raced my car for a full day at 'lil Talledega, motor was perfect, and still got 28 MPG on the trip home :)

Good luck with your decision Joe.

Les :cheers:

 

With all the added HP and torque of a 383 or 427 ci would it be advisable to upgrade the suspension to some like the T1 suspension ??

There are a more then a few ppl that have HIGH HP and BIG CI engines from well known tunners ( and they spent BIG BIG BUCKS ) but did not do the suspension on their cars. I wonder if these cars get twisted or bent in some way from all this torque??

 

The 427 will make a lot more power just because of the bore. You can put bigger valves in the heads. Bigger valves = more airflow.

Personally, I couldnt afford a C5R block and at the time I did mine, my tuner suggested that he didnt trust the reliability of a resleeved LS6 block so I went with a Lunati kit.

I think you can make 50hp more with the 427 over the 382.

 

:withstupid: Did the same thing myself. I run N20 and will have a TT by the year end so the extra ci. are not that important to me. Really did the stroker to get the best and strongest parts on the market.

Here is what I would do...if you know 100% without a shadow of a doubt that you will definately never run any type of FI then I would bit the bullet now and go with the 427. If at anytime you might go with N20 or FI then I would get the strongest components and stick with the 383. :yesnod:

 

Go with the 427 motor and if you don't want to pay the outrageously expensive C5r block the new DARTON SLEEVES that MTI is now using and many others looks like it will be the REAL DEAL for 100% realiabily and at leat 50% cheaper than the c5r block. However, if you can afford the C5r block i can attest to the fact that it is ONE HECK OF A MOTOR!!!! And yes, if you go with a 427 you want to make it the 100% reliable and battle tested way that the C5r engine/race car makes the cubes, that being a 4.125 bore and 4.00 crank. Many tuners have said before and i agree with them that a LS1 motor should not use more than a 4.00 stroke as the rod/angle with a huge stroke is not desirable and go lead to oil consumption, reluctor wheel crank issues and other issues concerning long term reliability, etc. Before going with my MTI 427 C5R block Ls6 headed motor i had the big 4.125 stroke on a smaller 4.060 bore on a ironblock and had issues similar to those mentioned above prompting me to pay the extra $ to do it right!!!

Call JAYSON at MTI as its hard to beat a battle tested race motor 427 that they build and get a 2yr/24K mile warranty with it, as long as you use no N20 or other F/I. That being said, you could N/A drag race it every day of the year and if the motor fails MTI will fix it up 100% no questions asked (unless you used the laughing gas, etc.) and that's pretty AMAZING!!!! :cheers:





[Modified by MTI 427 Roadster, 2:08 PM 12/14/2003]

 

I have an MMS built 388 All-Bore(4.125" bore) and have not had one single problem with the sleeves. I also spray the motor. The one thing I notice of the all-bore over stroking alone is how it revs faster. The all-bore will possibly have less torque but you will achieve more hp going all-bore which will equate to better 1/4 mile times. Of course if you can do the all-bore then you might as well just spend the extra 3k and stroke it to a 427-434-436... :yesnod: My buddies 434 was just unreal when he stomped on it with no power adders.


[Modified by C5-VERT, 6:03 PM 12/14/2003]

 

Bigger motor will always have better area under the curve (everything else being equal)
Peak HP may be hindered by intake restriction (today), so peak HP might be comparible between the two.

However, don’t forget that once a good intake (LSX maybe?) comes out, just swapping it out may uncork “the difference” between the two.

The bigger motor will always be much nice to drive on the street either way due to extra bottom end. :D

I guess it depends what you wanna do with it. For ¼ racing you can always just gear down, so TQ doesn’t matter, on the street/highway it’s a different story….

Hope this helps :cheers:




[Modified by EuG, 9:58 AM 12/15/2003]