Pro charged 300

Pmelsness90

Well-known member
I was advised to start a thread here for a pro charged 300. Looked high an low for someone who has done this didn't come up with nobody but doubt I'll be the first, between me an my machine shop were putting together a .40 over 300 with a fully ported and polished head with oversized valves along with some roller rockers, cam and pistons are still to be determined beins my original plan was to be naturally aspirated. Now after speaking with my machinist were goin with a p-1sc-1 pro charger, we agreed that ten pounds of boost is what were going to try to make it happy with.i have a offenhauser c series intake with some efi manifolds, my two questions is has anyone done anything with the Holley sniper efi setup? And what do the boosted 300 guys do for ignition/timing setups? This will be driven every chance I get an will be on 92 ethanol free pump gas.
 
The Holley efi will work for your boost levels, but I'm pretty sure they are only rated to like 13 psi. So that doesn't leave alot of room if you decide to push it further. The FiTech 600 and 1200 Hp systems are rated to a little over 20 psi boost pressures. As far as how well they actually work, I cannot offer any firsthand experience but on YouTube reviews they seem to slightly outperform a well tuned carb. Either system will likely work just fine
 
The Holley Sniper EFI 4150 Super Sniper 650 will handle up to 21 lbs of boost. PART# 550-519

Use a DS2 distributor, lock both the mechanical and vacuum advance so the trigger signal never moves from where it is set.
The signal is fed to the Holley Sniper by way of the MSD adapter cable #8869
The Sniper now controls the timing and triggers the MSD ignition by the White wire from the sniper to the white wire of the MSD ignition box.
The MSD 6AL has a rev limiter.

You can start conservative and retard the timing 1 degree for each pound of boost.
 
If the Procharger is to run at 10 lbs of boost, at what rpm will that be at and what drive ratio between the engine's crankshaft pulley and the supercharger pulley will you use?

The reason for asking is a centrifugal superchargers boost or pressure increases as the engine rpm increases.
The other problem is Procharger has never released compressor maps so it is hard to pre-determine a drive ratio.
You have to guestimate and try a ratio, then based on results you can then make changes if needed.
Looking at Vortech's compressor maps it appears a 1.7 drive pulley ratio may get 10 lbs of boost by 5500 rpm.
I will be at the PRI trade show this Dec and will visit their booth.

The other part of this is the engines volumetric efficiency needs to stay high at 5500 rpm in order to keep the superchargers compressor running near the center of the map and not veer off towards the surge zone.

Looking at a ported big valve head with intake flow numbers just over 200 cfm and a cam profile with (not less than) .050" intake durations in the 230s and exhaust durations in the 240s on a 112* LSA in order to keep the VE from dropping off at a steep rate
 
The Holley sniper efi with the ds2 sounds like what I'll end up doing, will be able to keep the wiring to a minimum that way, as far as rpm to boost levels will go 10 pounds is the initial goal, I'm hoping that it will peak power around 4500-5000 just so I don't have to wrap it to the moon to get power out of it, as far as pulleys pro charger said to give them a call back an they could advise me on some pulleys so more than likely it will be trial an error on those, this is my first forced induction build so I'm trying to make sense of all the witch craft and magic needed to build a boosted engine.
 
As far as boost levels go and correct me if I'm wrong once I get the pulley sizes correct why couldn't I put a blow off valve on it to control the boost in the higher rpms so I could get full boost down low be able to maintain it threw the RPM range.
 
pmuller9":314dv4f0 said:
The Holley Sniper EFI 4150 Super Sniper 650 will handle up to 21 lbs of boost. PART# 550-519

Use a DS2 distributor, lock both the mechanical and vacuum advance so the trigger signal never moves from where it is set.
The signal is fed to the Holley Sniper by way of the MSD adapter cable #8869
The Sniper now controls the timing and triggers the MSD ignition by the White wire from the sniper to the white wire of the MSD ignition box.
The MSD 6AL has a rev limiter.

You can start conservative and retard the timing 1 degree for each pound of boost.
How did I not find that one?? I might go with that over FiTech as it seems to have a lower profile and just looks better visually.
 
Pmelsness90:3rnepg01 said:
As far as boost levels go and correct me if I'm wrong once I get the pulley sizes correct why couldn't I put a blow off valve on it to control the boost in the higher rpms so I could get full boost down low be able to maintain it threw the RPM range.

Here's what it looks like if you blow off the extra boost.

Below is a Vortech map that is close to the ProCharger p-1sc-1
The yellow vertical line represents the supercharger geared for 15 lbs of boost (pressure ratio of 2) at 6000 engine rpm and hits 10 lbs of boost at 5000 engine rpm (pressure ratio of 1.7)
Notice the compressor rpm is about 43K at 15 lbs of boost.

The horizontal line is where you hold the boost at 10 lbs (pressure ratio of 1.7) by blowing off the extra airflow.
At 6000 rpm or 43K compressor rpm the horizontal line goes to the far right where compressor efficiency is low.

It looks like it can be done.

Vortech%20Map.jpg
 
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That makes pretty good sense , once I get my motor back from the machine shop and start getting it put together and tuning I'm sure more questions will arise.
 
That makes pretty good sense, once my motor returns from the machine shop and tuning begins I'm sure more questions will arise.
 
For a distributor the current one I have is the original 240 that I put a pertronix ignitor kit in, I am able to wire that in to a msd so is there a reason I will need to switch to a ds2 or will my current one work?
 
If you use the Holley Sniper the distributor wires into it not the MSD box.
The MSD box is triggered from the Holley sniper.
To answer your question, the Holley Sniper can be wired to your present distributor with the pertronix unit.
 
I forgot to ask you which Pertronix Ignitor do you have. Ignitor, Ignitor 2 or Ignitor 3
The Ignitor 3 is multistrike and cannot be used to trigger another device.
 
I will have to look I can't remember off the top of my head I believe it's the ignitor 1, I was researching that earlier an came up with that, I'll check when I go to the shop tomorrow.
 
I'm leaving that up to my machinist, I'm sure pistons will be forged as far as rods I don't know what the plan is, tell you asked I assumed stock 300, I've got 240 rods that could be used as well
 
The 240 rod requires a piston with a 1.2" pin height. Not the best match for a street blower piston.
The pin needs to be lower in the piston so there is room for a wide upper ring land and a deep dish.
Also for supercharged use you want longer piston for bore stability.
This is the piston for a 240 rod on a 300 crank.

The rod for your build needs compression strength and more so than for turbocharging.
The stock 300 rods should hold up to 10 lbs of boost but I would not want to limit myself incase I wanted more power in the future.

You have two options for reasonably priced "H" beam rods.
They are BBC rods with the small 2.100" journal. The rods are 6.385" long versus the stock 300 rod at 6.210"
The rod width at the big end is the same as the 300 rod at .992"
Molnar CH6385NTB8-A or the Callies/Compstar CSB6385DS3B9AH
https://www.dropbox.com/s/dwdhm0yxuqrs57q/molnar-rod-side 1.jpg?raw=1
https://www.dropbox.com/s/xcoizohhszoez5x/Compstar rod resized.JPG?raw=1
 
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I will pass this information along to my machinist, I'm going to assume stock rods will be used but I don't know for sure.
 
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