Engine Compression/Parts Questions

Trupiano · Dec 12, 2010

Ok guys so I'm doing alot of reading trying to understand the parts of an engine a lil more and how it all works, so when I purchase a blower and internal parts, Ill know what Im looking for. So I get the Hemi comes from the "hemispherical shape" of the pistons "domed shaped head", and our compression is 9.6:1. So eventually I'd like to lower my compression to 9.5:1 or a lil lower for boost. Ive found that 9.5:1 or less is recommended. Couple guys were telling me that when I redo the internals I should do the 392 stroker kit (6.4), for a lil more power and I'll get some nice forged parts. But the 6.1 has a 10.3:1 compression ratio which is waaaaaaay to much for a boosted applications, so the 6.4 would be far too much. But lets say I did decide to go with a 6.1L crankshaft, couldn't I get dished pistons to reduce the compression to around 9.5:1. Just throwing ideas out there and seeing what info I get back. Let me know what you think and any technical info you have. Please keep this one on topic :greenchainsaw:

03MopaRamman · Dec 12, 2010

Interesting, Kenneth will prolly chime in on this one or even Greg!

Trupiano · Dec 12, 2010

You know me Danny, lol I'm always leaving room to go bigger! And I love reading all this and learning more about how it works.

Trupiano · Dec 12, 2010

Ok so I just read the main difference in the 5.7 and the 6.1 is the stock bore size. Stock for a 5.7L is 3.917 inches and 6.1L has a stock bore size of 4.055/4.060 inches. So a 6.1 is about the same as a 5.7, so a 6.1 crank wouldn't do anything.

Ok new question, 6.4L crank and dished pistons. What would the compression be?

Redtruck-VA · Dec 12, 2010

Ok, here is what I know. If you want big boost you can go 8:1 compression and basically there are combinations of pistons and chamber sizes to get anything you want in between. Probably a 8.5:1 compression and a cam designed for forced induction would be what you want. Inertia has a the Embalmer cam they say is for Forced induction. Also they can do custom chamber work to dial in a specific piston to a CR of the customer choosing. I been looking at 6.1 heads with custom chambers to get 10.25 CR on a stock block. But just researching at this point. Folks with real experience with doing this should pipe in and give you the skinner. Use my input only to stimulate ideas.

Trupiano · Dec 12, 2010

I prolly wouldn't go over 12 lbs of boost. Yeah 6.4 crank is out of the question, and 6.1 wouldn't do much. So for boost, it's stick to OEM specs, but I can upgrade to forged/lightweight parts. I can get flat-top or deep-dish pistons and over-bore to reduce compression to anywhere from 9.5:1 to sounds like 9.1:1 which would be perfect. I definately learned a ton tonight! Thanks VA and Danny! If you got any other ideas opinions lemme hear them.

Redtruck-VA · Dec 12, 2010

My 2 cents is forged pistons, 8.5 CR, 15# boost. Spend a lot on a inter-cooler upgrade. No need to spend a lot on heads as Force Induction takes care of flow. Clamp the timing to keep from breaking the engine and tune it on a dyno for max output. That truck will be more fun then a room full of naked ladies.

chefred112 · Dec 12, 2010

wanting to learn some of this as well...

KGBIGCOUNTRY · Dec 13, 2010

I have no idea to be honest. Pm Sam or hit up either Sharadon or Inertia to get you going.

Trupiano · Dec 13, 2010

Redtruck-VA said:
My 2 cents is forged pistons, 8.5 CR, 15# boost. Spend a lot on a inter-cooler upgrade. No need to spend a lot on heads as Force Induction takes care of flow. Clamp the timing to keep from breaking the engine and tune it on a dyno for max output. That truck will be more fun then a room full of naked ladies.

The procharger is the one I like, centrifugal (which is more efficient) and it's easier to up the boost, with a smaller pulley. Also the procharger comes with a pretty big intercooler, so that's a plus. I know the higher compression you have (and boost levels): the lower coolant temp you want, higher octane to reduce any KR(knock) and the lowest intake temp you can get(cooler air).

So like I said, dished pistons, and over bore will significantly reduce the compression. Forged everything, port the heads, and possibly a better/lightweigh crankshaft. But these are just ideas right now. I have to get the fuel system the way I want it first = P

edit: and a cam to match!

HKkid · Dec 13, 2010

Trup, its only money...what are you waiting for it will grow back. Or there's this chick named Visa that gives out money so I've heard.

Trupiano · Dec 13, 2010

Hahaha, engine internals wont be till the truck is paid off in a year and a half. Procharger will be as soon the gears/DTT are done, and all the fuel supporting mods are ready. I'll get a loan before I ever use a credit card. I use my credit card only for gas, and then pay it off each month. Emergency situations all it's for really.

truckin151 · Dec 13, 2010

If and when I decide to go this rout (which I probably will eventually) I either want to go with the SMS kit which is a twin screw design which has no lag and will build power as soon as you touch the gas, or go with the procharger with the quiet bearings so it makes no noise but acts more like a turbo system...

Trupiano · Dec 13, 2010

What I like about the procharger, is the truck runs just like normal if you stay out of the boost(higher rpm's) but as soon as you floor it, VROOOOOOOM! Heard it's a lil more efficient as well, and it comes with an intercooler. SHIBBY!

truckin151 · Dec 13, 2010

I don't know man if I'm dropping the dough on a supercharger I'm going to want the power throughout the power band not just in the upper rpms

HKkid · Dec 13, 2010

Trupiano said:
Hahaha, engine internals wont be till the truck is paid off in a year and a half. Procharger will be as soon the gears/DTT are done, and all the fuel supporting mods are ready. I'll get a loan before I ever use a credit card. I use my credit card only for gas, and then pay it off each month. Emergency situations all it's for really.

I hear that man...I have no card, too much of it would be spent on the truck. So how far out before the fuel mods will be done?

Trupiano · Dec 13, 2010

Nah, Im planning on 12-15 #'s of boost. In lower rpm's the truck wont be driveable. I don't wanna spin out every time I hit the gas a lil. This way I'll feel the normal power plus a lil more down low, and take off like a 747 when I want to hit it! Lol I can chage the cam out for a more torquey one, and that'll be enough for me.

truckin151 · Dec 13, 2010

That's the thing, with the twin screw you are building power witht the rpms increasing, so you won't be running a full 12psi at idle or part throttle but it will be there on demand. Its more stream line power than the turbo or procharger as you are not waiting to bild the boost before it kicks in

Trupiano · Dec 13, 2010

Fuel Mods
1. 255 Walboro Fuel pump... one, maybe two of them in a dual setup, not sure yet.
2. New stainless fuel lines
3. Fore Precision Works Billet Fuel Rails
4. Siemens 80# Fuel injectors (8)
5. Aeromotive 13129 Fuel Pressure Regulator

Supercharger Mods
6. Srt-4 Map Sensor
7. Boost Guage
8. Fuel Pressure Guage
9. AFR Guage

10. Procharger

Once those are done, it's ready for the supercharger! So I would say, I'll be done with the 4.56/Dtt by April, Fuel Mods by August, and Boost Mods by November.

More Boost Mods 12-15#'s
11. 6.1L Crankshaft
12. Forged Dished pistons
13. Ported Heads
14. Forged Lightweight Connecting Rods
15. 6.1L Springs/Retainers
16. Inertia Built Custom Supercharger Cam

17. Possible Over Bore, but not far a LOOOOOONG time.

truckin151 · Dec 13, 2010

all im seeing there is $$$$$$$$$$$$$$$$$$$ and a whole lot of FUN

Engine Compression/Parts Questions

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