Critique my First Engine Build

[slowcamaro]

SBC 383

Crank- 4340 eagle crank 3.75" stroke
Rods - 6" eagle h-beams with ARP L19 bolts
Pistons- SRP dish
Heads- AFR 195s or 210 SPEC heads(if still available at the same price)
Cam?? - 230/242, .520/.560 lift 114 LSA
Intake/Carb- RPM Air Gap or Victor Jr. and 750DP

9.25:1 CR

Now the cam is where im unsure as at first the car will be carbed and later i'll be adding a centrifigal supercharger and fuel injection.

Tell me what you think and what may need tweaked a bit. Im pretty set on the bottom end as my friend works at the machine shop and i can get a deal on the eagle/srp rotating assembly.

[slowcamaro]

I did a little reading on the ATI site and they suggest a cam with .010 more lift and 10* more duration on the exhaust side.

would 235/245 .535/545 work a little better?

[yody]

the second cam you mentioned would be more suited to the motor if you can get the compression up some, 10.1 would be perfect for a decent street motor with alm heads, even 10.75-1 is easily doable, but since you didn't mention HP goals 10-1 would perfect for the street, and teh second cam you mentioned with it. A lot of people design motors and say what they are going to be doing later, you should really make some decisions, if its going be awhile off before the charger I would put a cam with less split duration and less LSA, and change the cam out when you go with the supercharger/injection.

[Blown353]

I was going to say bigger on the cam too. My cam is 242/254 @ .050, .540/.580, 114 LSA. Max lift will vary based on what your valvesprings can take, but I would go more duration, especially on the exhaust side, than what you have listed. A very well respected centrifugal supercharged engine builder helped me spec my cam, and the combo works EXTREMELY well.

Definately try for the 210 spec heads. The exhaust port on the 195's is OK but I'd like to see more exhaust flow down the road when you add the supercharger. The more exhaust port flow you can have, the better! (but don't forget the intake too, better intake ports mean you can make the same power with a larger supercharger pulley, meaning lower intake temps.) Honestly, even on the 210 spec heads I'd like to see better flow numbers on the exhaust port at .200 and .300 lift; while not bad they could certainly be better. A good rule with heads for blown engines is shoot for as high of an I/E ratio as you can.

Yody has a good point. If you're not going to add the S/C for a while then put a different cam in it that will run better naturally aspirated and change it again when you're ready for the supercharger.

Something else you didn't mention, but definately have the pistons ceramic coated on the top, and I'd dry moly cote the skirts while I was at it. Also don't forget a little bit wider ring gap since you're planning to add boost.

Troy

[yody]

I just realized somethign!! your 9.25-1 is for the supercharger.....duh. Just make sure you definetly are going super charger and not pipe dreaming. 210's will be a good choice, for the reasons mentione above. A little big for an N/A 383 with 9-1 compression, but will still work good. 195's will work either way, but will more of a compromise if you really stick the charger on. I think you need to decide 2 things
1. are you really going to supercharge it
2. what kind of power are you looking for? max HP or give up a little power for streetability?

[slowcamaro]

Well first off thanks for all the input. Now let me try to address some of the issues/questions.

1. Yes I really plan on supercharging it, though it may not be immediate.
2. Power wise I dont really have a set goal, Id like to get 400 to the wheels N/A..on the boost well thats just a bonus.

So assuming the engine is at 9.1-9.5:1 compression with the 210 heads *though not optimum now* can you recommend a cam?

[zbugger]

If you're going to run that low compression, I'd recommend tightening the LSA to 112. 110 even would be better, but maybe not necessary. You'll get better cylinder pressure which will help combustion for you.

[Lowend]

A couple of notes here.
#1 I would run a 5.7" rod if you intend to have a supercharger. The benefit from the longer rod is minimal at best and in this case you are better served by getting the rings out of the piston pin area.

#2 definately use a Vic Jr style intake manifold

#3 Definately use the 210cc heads, they are much better suited to the supercharger. Beware the 210's are spec'd with Solid Roller springs, so if you intend to run a hyd roller cam (that is what those specs look like to me). You need to specify the springs.

#4 take out a few minutes and work out a good evac system. This motor with a supercharger will not be properly served by a breather in each valvecover. I would suggest working out a remote breather tank setup.

#5 I am not one who tends to advocate the use of high duration cams with superchargers. They just don't respond well to a lot of duration (open exhaust valve builds no boost). I would keep the cam in the 230/240 range and keep the Lobe Seperation in the 114 range. Overlap is the enemy here.

#6 Budget extra for good fasteners in this engine. You should stud the mains for sure, and consider studding the heads.

#7 Buy good rings. Superchager engines are VERY hard on the piston rings. I believe SRP has a boost spec'd set of rings in the back of their catalog. DO NOT RUN BUDGET RINGS.

[slowcamaro]

1. I was thinking 5.7 seven rods originally but had found the 6.0 selection for the same price even a bit less than the 5.7's. If 5.7's will have a noticable benefit I will consider the minor cost.

2. Ok

3. Noted. Still looking for input on the cam. My original thoughts were 230/240 cam aswell..or at least close I was trying to keep the torque convertor in a reasonable range....I like to see everyones opinion. Springs will be purchased to fit the cam I eventually select.

4. Thanks...something i hadnt thought too deep into yet.

5. See 3

6. Mainstuds are definate, I wasnt sure about head studs but i was considering it, I'll talk to the machinist and see what he suggests, he builds a lot of high power dirt track engines.

7. Any brands you like here?

[Lowend]

I like Total Seal rings, but in general look for rings designed for use with a boosted application.

The 5.7" rod will not help with horsepower in any respect. The reccomendation is based on durability. If you look at a piston designed for a 3.75" (383) stroke and a 6" rod you will notice that the lowest ring land actually goes into the piston pin hole, leaving the ring unsupported in that area. This is ok with a naturally aspirated engine, but superchargers, N20 and Turbos produce really extreme cylinder pressures which can stress the rings. With a 5.7" rod the piston pin moves "down" on the piston and gets the pin out of the ring lands.

I will warn you on the head studs... they are a pain in the ass. They make it pretty much impossiable to remove the heads with the engine installed in the car. BUT again with a supercharger you are dealing with much higher cylinder pressures and studs will seat the heads more solidly on the engine. Along those lines, use good Head Gaskets; if they cost less than $35 each don't use them. I like the Fel Pro 1003's myself.

Take a look at the breather system I helped devise for Bob Spears' 69 Camaro if you want to get an idea how to pumb the system

[Blown353]

Other suggestions now that I think about it:

Find a machine shop that can provide a good enough surface finish on the block and heads to allow you to use MLS head gaskets (Cometics or otherwise.) That pretty much takes care of all the worries about blowing a head gasket, but be warned, if the surfaces don't meet the manufacturer's spec you'll be chasing leaks. Hopefully the machine shop has a GOOD surfacing machine, the right cutters (I like a single point PCD setup), and knows their feedrates/spindle speeds.

If you're really serious, considering picking up a piston oil sprayer kit from CV products. The relatively cool oil showering the underside of the piston will keep piston temps down (even with coated domes) which will not only help durability but stave off detonation. This trick goes back years and years and years and nearly all boosted OEM applications utilize piston sprayers. The kit isn't that much money, and you're starting from scratch anyways, so I'd highly recommend the little bit of extra effort to install them.

Troy

[yody]

all of that extra stuff is nice, but if you aren't running huge amounts of boost i wouldnt' worry about it, good rings and studs are a good idea though, and the correct camshaft

[cad]

Since you are set on AFR heads, and I can understand why since I'm running 195s...here are several articles/builds that AFR has provided that used their heads. Several are blown....
http://www.airflowresearch.com/articles.htm

[ProdigyCustoms]

We spec out and sell a lot of small block Prochargers, P1SC blow thorughs, for 600 HP. We usually end up in the 240 / 245 range, 114 LCs. I would see what you can do to get the compression down in the high 8s as the blower would like to do more work, but low 9s is OK. Heads, with a blower, never to much (within reason), and same for exhaust. She will be retty soft till you blow it, but will become a animal when you do.

[slowcamaro]

Thanks for the input guys, I'll see what I can do for the CR i could probably work it out to bring it down a bit more. As soon as figure out how much my tranny is going to cost me to rebuild, Im sending the block to the machine shop.

So I still have time to work on this combo.

[ProStreet R/T]

Definitely stud the heads and main caps, head studs can be a pain but well worth it. If you need to pull the heads with the motor in the car you can remove the studs (allen wrench in the center) and it's not a huge deal.

Cometic gaskets are awesome for strength but you better be spot on with the tune or other things will give way.

Do you want it to scream on the blower or work well N/A? mixing the 2 won't give you optimal results either way. If it's going to be a 6 month wait till the blower then screw it and build the thing for boost. If your talking years then put an N/A cam in it till then.

I prefer not to overcam blower motors, you build a lot more power under the curve and it makes for a much more civil vehicle to drive. 232/242 .540/.560 114 would be a killer blower cam and still make reasonable cylinder pressure when not in boost.

For blowers, D1SC or Paxton N2k, I personally love the paxtons but they all have their own quirks.

If your going to go efi do it right from the start, no need to buy all the stuff twice. You can find the FAST systems for a very reasonable price if you shop around.

[Frank69]

I don't have much experience with supercharged motors, so I'm looking to learn something here. Why wouldn't you want to use a small, dual profile hydraulic cam, like one of the Comp XE's (230/236 @ .050, .490/.490, 110* LSA)? Would be a great cam for his combo, normally aspirated. How do you guys think it would respond when supercharged? Too much cylinder pressure?

I also like the idea of using the 5.7 rods.

Frank

[ProStreet R/T]

With a FI motor you want a wider lsa to reduce valve overlap.