OK. I have been really looking forward to completing the 383 over the next several months. I have been slowly accumulating the parts for the build. I have not yet purchased the new rotating assembly. I was planning on getting an external balanced Eagle rotating assembly for $800-$900.

I am using the Vortec heads with the Crane Powermax 272 (.454/.480). I already have the shortblock for the 355 with about 5000 miles on it. Granted, it does not have your typical performance pistons, it has the stock cast dished pistons. Therefore, it will cost be approximately $900-$1000 more to build the 383.

I was playing with the numbers last night on Desktop Dyno 2000. Here are the numbers that I got:

w/ H.P. Manifolds and mufflers:
383 - 330 hp @ 5,000rpm; 392 ft.lb. torque @ 3,500rpm
355 - 327 hp @ 5,500rpm; 367 ft.lb. torque @ 3,500rpm

w/ small tube headers and mufflers:
383 - 368 hp @ 5,000rpm; 418/419 torque @ 3,500/4,000
355 - 367 hp @ 5,500rpm; 391/397 torque @ 3,500/4,000

Do these numbers seem accurate to you guys? If so, do you really think the extra 1 hp and 22 ft.lb. torque (w/ headers) is worth the $1,000?

To me, it seems that the money would be better spent elsewhere. What do you guys think?

 

The numbers that you're seeing are correct. With the whole intake and cam the same additional CI will have nearly the same HP at a lower rpm and the TQ will grow in relationship to how many ci added.

So what you have to do is gain air flow. Bigger carb/manifold/heads/cam to feed the bigger ci motor. Or just be happy with a TQ monster producing all that power at lower rpm

 

That's what I was really hoping for was the additional torque. But 22 additional ft.lb. of torque just doesn't seem like much. Is that enough to have a noticeable difference when driving the car?

My goal starting out was to get about 350hp and 400 torque. It appears that I can achieve the hp numbers and almost achieve the torque numbers with the 355. The 383 just sounds enticing, but I don't want to pop for the extra money if the gain in performance won't be noticeable.

 

KB Not my favorite brand but here's something that'll work well with what you have & make about 9.6:1 SCR 383" w/ your vortecs ... and not break bank:

KB164 hyper pistons w/ -19cc reverse dome for 6" rods ... about $250 on ebay.

scat or eagle capscrewed 6" rods .... about $225 on ebay.

scat or eagle cast INTERNAL 3.75" stroke crank ... about $225 on ebay.

Looks like about $700 for crank, rods & pistons ... local shop'll probably charge about $125-$175 to balance the assembly.

A cheap set of 8 1.6:1 RAR on INTAKE will help your cam alot for the 383.

I dunno if your numbers are any good or not ... but there's no replacement for displacement ... that's true here too ... go 383". Long stroke make lotsa low-mid tq. In a street car ... tq is what you feel & use most of the time.

Alternatively... you could spend your $ on a lower rear gear set & achieve similar sensation.

 

You might just need to run the DD2000 using the Crane 278 cam.

DD2000 is more accurate if you pluggin all the valve event numbers at .050 from the online cam cards.

I just know that when i went from hot rodded 355 ci making low 400 hp to a very hot 383 it was a world of difference. I had so much more TQ that I didn't even shift down to pass people. I just left it in OD

 

won't the vortec heads have to be machined in order to run the 1:6 rockers?

 

I am in the process of also assembling a 383 stroker. I called Dirt Track Thunder. The were great to deal with. I am getting the whole assemble balanced to 7000 RPMs. Just remember the eagle kits are not balanced. The come either internal balance or external balance. These guys spin balanced the whole assembly. I went with a Eagle 6" rod bushed rod, Eagle stroker crank for internal balance, Wiseco Forged Pistons, and all the bearings and rings. All balanced and shipped for $1049. I heard about them from some local guys who were very pleased. I was going to go for the $875 Eagle kit but I wanted it balanced. It is very hard to count Desktop Dyno it is either close or way off.

 

I cannot use the 278 cam because of the stock torque converter. It has too much duration. I think I did input the valve event numbers from the online cam card. I put in the degrees when the valves open and close.


James B: I believe the only machining that needs to be done is to drill the pushrod hole to a larger diameter. However, I also ran the numbers with the additional lift that the 1.6 rockers provide and it only added 1-2 hp and about the same amount of torque. Of course, I ran those numbers with 1.6 on both the intake and exhaust.


windsoreight: The kit that I was looking at was the Eagle Strip/Streep externally balanced from CNC-Motorsports. They balance it prior to shipping. It is about $825.00 shipped to your door. The site is www.cnc-motorsports.com


I guess I am just running up against the limits of what I can put in the car with the stock torque converter. Of course, if I could even go with the bigger cam, it would just reduce my lower end torque. I just thought that the 383 would make tons more torque than a 355.

 

i had a very nice 355 with a Crane 272 and Edelbrock 2101 Performer and Holley rojection and Hedman headers with trick flow heads. i don't remember the dyno numbers but HP and Tq were both in the 350 range.
See sig for the 383 I'm running now.
In addition higher peak numbers, the 383 has a very flat TQ curve so that the power is useable at much lower RPM. With my Keisler 5 sp, I can accelerate nicely from 1400 rpm in 5th gear.
No way I could do that with the 355.

I other words, you have to look at the area under the curve. The 383 has much more area under the torque curve and hence more usuable torque where you operate most of the time - in the 2000 to 4000 rpm range.

 

The 383 makes a lot more torque dow low so you need to look at the curve. It makes more torque BELOW the peak. This is the reason to build them for a street car or even a road racer. If you were considering building a 383 for a drag strip only car, the added torque below the peak is not a big draw.

Do a DD2K model of 2 identical engines and only change the stroke. The peak numbers only go up a little due to the displacement but the torque curve is FAT in the lower RPM ranges. This is good if you want to keep the stock converter too.

-Mark.