Was going to do a 383, but I am currently thinking of revising that down to a 355, just so much easier on parts, and what I really want is the RPM potential over raw power. (gearing and speed issues)

The other joy of a 355 is that a performance 355 can have a 2.5" exhaust and not be choked. And 2.5" exhaust systems are a COTS item.

So I am thinking of a 355 that operates under 7200 RPM. With a solid roller cam with a 4/7 swap ground in. I like dealing with Cammotion, but compcams I think has gentler lobe profiles which is going to be an issue on a motor that is going to require longevity and reliability.

I am leaning towards Hypereutic pistons because of the low expansion properties, and at 10.4:1 compression with flat tops detonation is not a huge concern of mine.

I am leaning towards a weiand Team G or Edelbrock Vic Jr, with a 1" HVH spacer.

A holley 750 will sit on top of that.

I have some 6" billet rods, a Fluidampr (the good one and not the streetdampr), a mcleod aluminum flywheel. I need some pistons, and a crankshaft.

I am not quite sure about heads at the moment. I theorize I need something about 185cc and 282cfm at .6 lift. Which as I am finding a mythical item. I dont want to get to big with the heads, and definitely keep them under 200cc, and definitely 64cc or smaller chambers. There is always AFR 195 competition heads I guess. Though the Big valve on a 355 gives me the creaps, as modern engine design keeps moving to bigger ports and smaller valves. So I wonder if some GMPP fastburns and give them a good once over would do the trick? I would appreciate some thoughts on the issue.

This brings me to the camshaft. I like dealing with Cammotion in Lousiana, and I loathe dealing with Compcams. Dont have much experience from Crane. I was sorting through the cammotion catalog, and for what I want to do I am leaning towards 274/274 112 LSA 4 degrees of advance or there abouts. 50 degrees of overlap will do good things for engine vacuum with the single plane, and if I get heads with a good exhaust valve the single pattern wont hurt me. The cammotion lobe I was looking at was 274 at .02, 239 at .05 and .405 lift at the lobe. Is this too aggressive for a street motor, or should I tame it down with something closer to the compcam lobe of 274 advertised, 236 at .05, and .376 lift at the lobe?

I have a monster oiling system, and I believe I have hooker supercomps already (sitting on the car), and magnaflow is coming out with a 2.5" C3 exhaust. I have a howard stewart stage 3 water pump, so It would be kept pretty cool.

Hmmm I wonder about an 800cfm Q-jet sitting on top of a spreadbore edelbrock RPM intake...... I could hook up some of these miscellanious wires that are hanging around in my engine bay, and better cruise economy.

 

Having tried victor Jr single plane on 355s no way I would run it over
a dual plane. What modern engine are you talking about with small valve.

 

LS1 and 2s use a 2.00 and 1.55 inch valve on 5.7L and 6.0L motors.

The LS7 on the other hand has HUGE valves. 2.204" intake and 1.614 exhaust valves.

I have single plane on my L82 that the previous owner put there.

 

Well the LS1 has 2.00 for a 3.90 bore when they went to the 4.00 bore
LS2 It still had a good percentage of valve area for the bore size.
The old 2.02 valve size in a 4.00 bore, percentage wise is not as good
as the 2.00 in a 3.90 bore. obviously when the bore size went to 4.125
for the 427 they needed bigger valves to help the percentage to bore size. The small 4.6 liter overhead cam fords have a very tiny around 3.50 bore they have two intake valves, they have a huge percentage of valve area for the size of the bore. All of the modern 4 cylinder, V6s and V8 japanese or german cars have two intake valves means they have huge amounts of valve area, with the added luxury of two small cross section intake runners.

 

LS1 has a ratio of intake valve area to bore area of 26.3%
The 350 SBC ratio is 25.5%
the LS7 ratio is over 28%

So I am sold on the AFR 195s, the 2.08 valve will give me a ratio of only slightly more than the LS1 (27.04%)

 

hyper pistons have a upper rpm limit. mine smeared in the bores exceeding 7000 rpm. SRP Forged with 6.125 - 6.250 rods is the way to make higher rpm 355's

 

i have a set of speed pro hyper pistons if you want but there .040 over, w/coated skirts. 2k miles on them

 

well I already have 5.7" H-beam Eagle Rods
and 6" Crower billet rods.

I intend to use one of those 2.

I figured that they would be good because of their use in Oval track racing.

Guess I have start relooking into forged pistons.

 

What length rod are they for?

 

5.7
there were in my 'enginefactory' stroker engine

 

Think I will pass. I am looking to do a long rod motor.

 

So I have been looking at solid roller companies.

The crane cam "street rollers" are little better than a hydraulic roller, might was well not even bother.

Who else makes an easy on valve train solid roller camshaft?

I think I need an IVC between 60 and 67. (so 64ish)

 

The cam ramp rate of a Crane street roller is only going to lift the valves slightly fast than something like CC EX series of hydro rollers. You have to dig down to lobe profiles and figure out a custom combo to get fast open and closing valves.

 

Since most of the rest of the stuff I am slowly collecting is crower, I might as well get the matching set.....

I am noticing that the difference between a lot of cam companies difference between .05 and advertised is somewhere around 40 degrees. Crane SR run around 50.

What I need is a cam company willing to grind me a step nose solid roller cam with a 4/7 swap. Cammotion will press on a cast distributer gear. I suppose that if I have a low lift lobe, I could go with a large rocker ratio.

Crower makes some good large ratio rockers.

What is the reliability of that idea?

 

So lets see here:

Overall engineering criteria:
Reliability and ease on parts
Maximum use of component capabilities

Redline 6800 rpm (7000rpm tachometer)
Top speed 158 mph (160 mph spedometer)
3.36 rear end (required for speed and RPM criteria)
M21 4-speed

So if I cannot get .6 lift there is no point in using the AFR 195s. Leave to much on the table as far as potential. If I am going to be limited to .5-.55 lift based upon the reliability criteria, I may have to move down to the AFR 180 Competition package. Then I would definitely be using everything the heads had to offer.

 

If you want a low expansion forged piston check Mahle. I think SRP makes one too.

 

That is the way I am leaning. I think both mahle and SRP are made of low expansion 4032 aluminum.

 

BTW ... much-vaunted newer LS7 427 based on LSx w/ over 500hp has hypereutectic pistons ... so does new 430hp LS3 ... but keep in mind both based on designs intended for computer-controlled mixture & timing that prevents detonation. However, new CT525 circle track crate w/ + 520hp has hypers too (as do ALL GMPP CT crates) but it has carb intake. There's a ton of GMPP CT motors running short track w/ carb & dist ... I've never seen one suffer a catastrophic failure ... no smeared pistons or otherwise. I'm sure some have blown up somewhere, but I've not seen it ... and those are the GMPP crates that have NO warranty.

true ... many mfgs have forged offerings in both low & HI-expansion.

Common low-exp forging alloys are VM75 & 4032.

Conversely, 2618 is common HI-exp forging alloy ... it usually requires lotsa clearance & is noisy when cold.

 

Do you know some good Hyper flat tops that will survive sustained usage between. 4500-7000 rpm?

On another note:

If I use the AFR 180C package (they only advertise flow upto .5), I could possibly use a single pattern cam with these lobes:

R-2381 270'(.02) 238'(.05) 0.325"(lift)

With some 1.6 ratio rockers that would have a nice mild .520 lift. Not really sure if that is even worth the solid rollers, but I guess i can call. If I were to use those lobes I would probably put it on a 110 LSA with 5 degrees of advance.

 

Just a comment on your exhaust logic. If you are going to spin a 355 faster than the 383 you are pretty quickly going to need the same exhaust as the bigger engine. A 383 @ 6500RPM is pumping out the same amount of exhaust as a 355 @ 7000RPM.