Can my motor handle a procharger? - Lateral-g Forums

MaxHarvard · #1 06-30-2006, 03:27 PM

I'm seriously looking at getting one, once i find a real job in the real world! I'm just wondering what you guys think if i were to put it on the current motor... or would i need to beef it up, rebuild it and start over?

Currently, its a SBC 350 making 445hp and 445tq
4 bolt mains
stock crank shaft
forged rods
forged pistons
AFR 195cc heads, 2.02, 1.60
Xtreme energy 284 cam
6 qt oil pan
air gap intake
demon 750 carb
HEI distributor.

I'd really like to hit 550-600hp. Is my combo going to hold up, or do i need to replace some stuff?

Blown353 · #2 06-30-2006, 06:35 PM

What's the compression ratio and exact cam specs?

You'll probably be OK for a low-boost setup if your CR is around 9.0-9.5:1, although I would highly recommend a teardown to coat the pistons and open up the ring gaps a bit, which means while you're there you could benefit from a SC-specific grind cam.

What headgaskets are you currently running?

Carb mods and a boost retard of some sort (MSD 6BTM or equivalent would be easy) would also be a must.

550-600hp is not asking much if your CR is in the right ballpark.

Still, don't expect to do this for less than $4K or so, it adds up quick (SC & bracketry, good carb hat, carb mods, fuel system upgrades, etc, and I highly recommend spending the extra $200 or so to retrofit a GM spring tensioner on the SC bracket. Procharger's stock tensioner, in a word, sucks.

ProdigyCustoms · #3 06-30-2006, 07:07 PM

Well, as Blown mentioned, compression and camshaft arer the two major factors. And he is correct, the 550HP to 600HP is a cake walk. I disagree on his cost estimate, $3000 should cover it. If the motor is 9 to 1 or so, and has the peoper camshaft, it will only need about 8lbs boost to make the goal. It will not take any rocket science to do a low boost carb mod, a special hat will not be required for just 600HP. There is plenty of $$$$ for fuel system upgrades left after the super charger pruchase (if you buy it at the right place hint, hint) and still do it for less then $3000 total.

Blown353 · #4 07-01-2006, 12:39 AM

Frank is right (as usual) but I'd still spend the money on a good hat even at low boost because the poor airflow distribution characteristics of junky hats will lead to some cylinders being leaner than others and may cause detonation issues. This isn't as big of a problem at lower boost / volume compared to high boost / volume but I strongly believe buying a good hat is money *WELL* spent. All sorts of driveability and performance issues can plague the engine with a poor hat and a good one isn't much more money.

There are a lot of bad hats out there and only a few good ones. I like SDCE's hat, CSU's hat, and the EV hat. I know Scott @ SDCE put a LOT of time into doing flowtests on all the hats out there, and I know he spent months doing the R&D on his hat to make sure it would deliver a very uniform amount of air to each barrel in the carb with all sorts of flowrates and boost levels with the hat pointed in any direction.

MaxHarvard · #5 07-11-2006, 11:25 AM

Thanks guys... A lot for me to think about. I have 11:1 compression right now. I know i'd have to turn it down a bit.

Do you think those AFR heads are big enough? Also, will the stock crank hold that kind of power? I know the rods and pistons will.

The head gaskets i think are fel-pro... nothing too fancy i think.

EDIT:

How about selling this motor i have... and buying a Nelson Racing Engine blown 355? How would that be for you guys?

You think i could get $4-5K for my current motor with only 800 miles on it?

nitrorocket · #6 07-11-2006, 12:23 PM

Lower the compression to 8:1 and you will be fine for 600+ RWHP with a Intercooled D1SC on 91 octane. The crank is by far the week link, it will be on the edge for sure.

Good luck!

Blown353 · #7 07-11-2006, 01:10 PM

Quote:

Originally Posted by nitrorocket

Lower the compression to 8:1 and you will be fine for 600+ RWHP with a Intercooled D1SC on 91 octane. The crank is by far the week link, it will be on the edge for sure.

Good luck!

8:1 is too low and outside the efficiency range for a centrifugal IMO. I'm running about 9.2:1 on 91 octane, non-intercooled for now (water injection though) with 15 psi of boost through an intake that flows 305 per port and heads that flow 290/220 @ .600 (and have very good midlift flow and a very good I/E ratio across the board)-- so that 15psi of boost doesn't mean I'm trying to shove too much air through crappy heads/intake.

Given that supercharger cams are longer duration and "nastier" than turbo cams, having the compression ratio too low means poor overall efficiency when off-boost. That's OK for a race car but a bad move for a street car IMO. Better to keep the compression up some and the boost down a little to maintain off-boost mannerisms. Granted, you will sacrifice some of the all-out HP and boost potential that you could have with a lower static CR and more boost but the engine will be much more pleasant when off-boost with the higher CR.

Like anything, it's a series of compromises, and for a street car with a centrifugal going more compression and less boost is the way to go.

nitrorocket · #8 07-11-2006, 03:23 PM

His cam really is not that big?

Blown353 · #9 07-11-2006, 04:15 PM

Quote:

Originally Posted by nitrorocket

His cam really is not that big?

True, his current cam isn't big (he would benefit from a SC-specific grind with much more exhaust duration) but the combo will still be much more efficient off-boost with higher compression-- and you can still run plenty of boost with compression in the low 9's.

Majik16106 · #10 07-19-2006, 04:51 PM

have to agree here with blown. i tell people the same things when building motors for turbo import street cars. we bump supras all day to 9 or 9.5:1 to up the response time, run less boost and keep her 91 oct friendly.

Keeping the compression higher and boost lower results in some sick throttle response across the rpm band, which is great for passing while cruising without sounding like your going wide open to 8k rpm. from a roll races catapult the car forward if gearing is right. plus once again, the off boost driving is much nicer.. much easier to drive a car around a parking lot, or in traffic like on a cruise night or something.

im building a similiar set up.. 9:1 d1sc intercooled 355. I did opt for the forged crank and rods to go with the pistons, as this car is a street car, but when it hits a track , it would live at road atlanta, so thats a ton of high rpm corners and straights. makes for much better out of turn torque on twisty roads.