What Would I Need

-

h340

Well-Known Member
Joined
Aug 13, 2005
Messages
57
Reaction score
0
Location
pennsylvania
I have a 1969 Dart 340, forged crank and forged flat top pistons, H beam rods, Hughes solid 5256AS cam, 750 Holley, J Heads light porting, rpm air gap. What would i need to do a Paxton blower on my car. i have MP Chrome Box and Distributor, would i need all MSD Stuff? What do i need for a carb? Do you recommend a bonnet or the big box piece the carburetor goes inside? Should i run Meth/water injection? i have a Mech. Fuel Pump now i am figuring ill probably need an electric one. Also how difficult is it to tune a blown carb motor? should i figure on putting in an A/F gauge? Sorry for all the questions, new to forced induction, any help would be great or some links to some build threads close to my situation.


Thanks in advance, Chris
 
What is your current comp. ratio? I assumed the engine is built. This may be a mistake. But if it is not, a set of low compresion forged pisons shoule be looked into. IMO, 8.5-1 max, low is better. (For the most part)

What would i need to do a Paxton blower on my car.
Paxton has kits that go from outta the box and on to the car complete. Use of the airbox is a good idea as to keep it simple. The extra cost is small @ around $500, or so bucks.

i have MP Chrome Box and Distributor, would i need all MSD Stuff?
I would go with the MSD (or equal) set up. It is actual easy to put togther.
What do i need for a carb?
A regular carb will work, but a blow through carb will really be a nice thing to have! If this will be "On the Cheap" as money will allow, then worry not and upgrade later.
Do you recommend a bonnet or the big box piece the carburetor goes inside?
Answered above. The box IMO isn't a bad thing.
Should i run Meth/water injection?
It may be needed like it or not. The more pressure introduced to the engine, the more of a need you'll have.

I'll let the been there done that fill you in.

i have a Mech. Fuel Pump now i am figuring ill probably need an electric one.
IMO, great idea.
Also how difficult is it to tune a blown carb motor? should i figure on putting in an A/F gauge?
I think a A/F gauge for any car and engine set up is a great idea and way to monitor the engine and it's running status. Tuning with one IMO is an excellent idea.
Sorry for all the questions, new to forced induction, any help would be great or some links to some build threads close to my situation.

Same boat here. I just try and make a list instead of a parrgraph of questions. :-D
 
I have a 1969 Dart 340, forged crank and forged flat top pistons, H beam rods, Hughes solid 5256AS cam, 750 Holley, J Heads light porting, rpm air gap. What would i need to do a Paxton blower on my car. i have MP Chrome Box and Distributor, would i need all MSD Stuff? What do i need for a carb? Do you recommend a bonnet or the big box piece the carburetor goes inside? Should i run Meth/water injection? i have a Mech. Fuel Pump now i am figuring ill probably need an electric one. Also how difficult is it to tune a blown carb motor? should i figure on putting in an A/F gauge? Sorry for all the questions, new to forced induction, any help would be great or some links to some build threads close to my situation.


Thanks in advance, Chris

Ideally, you'd need forged pistons that provided an 8.50-9:1 compression ratio, a Paxton blower and its mounting plate, a carb (600-750 cfm) that has been modified to "blow-thru" status, a bottom crank pulley to drive the supercharger (serprntine system, probably) and an idler pulley and mount for it. A serpentine belt of the right dimensions.... Cast pistons are OK IF you limit boost levels to 4 0or 5 pounds...

Also, depending on how much boost you want to run, a meth/water injector might be necessary. Up to about 7 pounds, you might get by without one, on pump gas. Over that, I'd bet you'd need one for staving off detonation.

MSD makes an ignition system for boosted cars that will retard your ignition timing with a dash-mounted knob, that gives you the opportunity to control timing "retard" either 1, 2, or 3-degrees per pound of boost, up to 15 degrees; your choice. This would seem to be a plus for pump gas users. The system is called an "MSD Boostmaster" and, as I understand it, it is an analog system and totally unlike the multiple spark discharge systems such as a 7-AL. I have one on my supercharged car, and, the output is said to be in the 42,000-volt range, which works just fine on my 10-pound, Vortech-boosted 360 Magnum.

You'll need a carb "bonnet" and plumbing from the blower to the intercooler or carb bonnet. I don't know anything about the enclosures that are used as an alternative to a "bonnet." Sorry.

An intercooler would be unnecessary below 10 pounds of boost, IMHO.

You'll need a boost gauge...

Blown engines like big exhaust.... at least 2 1/2", but, preferably 3" or more....

Get used to buying PREMIUM gas at the pump....

Speaking of gas, you'll likely need a fuel-system makeover. How extensive will depend on the boost level you choose.

You will probably need a new cam; supercharged and turbocharged engines seem to run best (fastest) with cams that have a lot of lift, but not much duration. Not much duration = 210-215 @ .050". Also, they like lobe center spacing in the 114-degree range. See... a new cam...

Hope this helps!!!:read2:

PS, remember, 8 pounds of boost increases your 340 (340 + 170) = to 510 cubes, theoretically...:cheers:
 
Bill, How do you come to this?


It's the new math... my mind gets fuzzy after midnite... Should have said 337 cid, Sorry

Logic, mainly. Ambient atmospheric pressure is generally referred to as 14.6 psi.
That is what a normally-aspirated engines has shoving air and gasoline into the cylinder when the intake valve opens,

Double it, to 29.2 psi and you now have twice as much air and gas (ideally) entering each cylinder, virtually doubling the output.

A 225 would act like a 450 cid engine, if two atmospheres (14.6 psi, ambient, + 14.6psi. of boost) were going into the engine.

Cut the boost to 8 pounds (an atmosphere plus a half, virtually) and you have a 337 (225 X 1.5) motor. Those are ballpark figures, but the concept is backed up in a lot of forced inducton books.
Makes sense when you realize that basically, an engine is an air pump, and more air moving through it is going to affect its output on a quantative scale.

Hope this helps,
 
One thing to watch for is comp ratio.
I don't know a lot abt forced induction but I have picked up on a problem with mine.
It's a 360magnum with a KenneBell kit on it at 8psi.
It wants to make hp but I have to pull too much timing out of it to stop it from detonating which is killing it's potential.Currently at 28deg total to stop detonation.
I believe some of the reason is that it's just a blower plonked on a std compression (8.9:1?)engine.
I'm led to believe an intercooler will overcome most of the problem so that's the route I'm going.
 
One thing to watch for is comp ratio.
I don't know a lot abt forced induction but I have picked up on a problem with mine.
It's a 360magnum with a KenneBell kit on it at 8psi.
It wants to make hp but I have to pull too much timing out of it to stop it from detonating which is killing it's potential.Currently at 28deg total to stop detonation.
I believe some of the reason is that it's just a blower plonked on a std compression (8.9:1?)engine.
I'm led to believe an intercooler will overcome most of the problem so that's the route I'm going.

I would look into the AIS Meth Injection System before you start chopping on your car to install an Intercooler. With only 8PSI it should work well.

Look into this kit here for around $360 it will fix your problem in a hurry!
 
One thing to watch for is comp ratio.
I don't know a lot abt forced induction but I have picked up on a problem with mine.
It's a 360magnum with a KenneBell kit on it at 8psi.
It wants to make hp but I have to pull too much timing out of it to stop it from detonating which is killing it's potential.Currently at 28deg total to stop detonation.
I believe some of the reason is that it's just a blower plonked on a std compression (8.9:1?)engine.
I'm led to believe an intercooler will overcome most of the problem so that's the route I'm going.

Put one of these on it and be done. This is the one I am using,
 

Attachments

  • MSD BTM 001.jpg
    86.9 KB · Views: 134
One thing that hasn't yet been mentioned is a higher-than-stock output charging system. Using an MSD, electric fans, electric fuel pump, etc. is going to kill your battery really quick and a stock low-output alternator won't be able to keep up with it.
We found this out building our latest club charity raffle car with a Paxton-supercharged 360. The last mod we did was add a higher-output alternator.
 
-
Back
Top