Which turbo?

carbureted

Well-known member
I've been contemplating a turbo for my 300, but I don't know which one. Keep in mind that this is just an idea for now. If this is a terrible idea, tell me now. I've never messed with them before so I'm not 100% familiar with what's out there but I have a decent understanding of how they work. My diesel buddy is suggesting a Holset HE351CW off a Cummins or another similar 60mm turbo, which I think would be a good choice, but I can't help but wonder if excessive wastegate mods would have to be done to tune down that turbo. I want to run low pressure in the 5-6psi area. (?) Whatever is low enough to keep it on no more than 94 octane and not destroy things.

What turbos are everyone else using? Here's my build so far. It's just a parts collection. I haven't had any machine work done yet.

300 block
240 head if NA or 300 head if boosted. (I have both at my disposal)
240 C5AE non oil hole rods.
Probe 11938 forged pistons with a 20.1cc dish. (CR with 300 head with unmodified combustion chamber is 8.38)
3/8" pushrods.
Crower 19212 camshaft.
Roller rockers.
Cloyes timing gear set.
Full internal balance.
Offenhauser C series intake
F600 HD exhaust manifold
And a Holley throttle body EFI (boost compatible) that I have yet to buy.
 
Need to change the actuator to reach your pressure limit, not a big deal. Actuators are readily available. The wastegate port is too small on that turbo. You will need to increase the diameter of the port to prevent boost creep.
 
Turbo_B":1zvet5sb said:
The wastegate port is too small on that turbo. You will need to increase the diameter of the port to prevent boost creep.
Do you think it would just be easier to weld it shut and run an external wastegate? I'm seeing talk online of diesel guys who have to open up the wastegate diameter to an inch and they're obviously using much higher pressures than I will be.
 
I've decided I want to fork out the money for a quality, water-cooled aftermarket turbocharger. I've kind of narrowed it down to two turbos but am still open to suggestions. One is the Garrett GT3076R, but I'll probably want the 0.82 A/R instead of the 0.60 on the graph.

GT3076R_enlarged.jpg


My other option is the Garrett GT3582R.

GT3582R_enlarged.jpg


Both of these are actually on Garrett's website under a tech article using a Ford 302 as an example, so they're good for the engine size. I'm leaning toward the 3076 because it's smaller and would spool quicker and be better for lower-RPM street driving. The 3582 is a bit bigger and more for top-end.

Do you guys see any issues with either of these?
 
if the heads are not ported and without an intercooler, at 6 lbs of boost and 5000 rpm
the pressure ratio will be 1.4 with 30 lbs/min of air.
If you run a good intercooler the airflow could go to 35lbs/min.

The GT3076R would be the better match.
Spool up time is determined more by the turbine housing A/R.
You have a choice between .63 or .82
The .63 will give much better low rpm spool time for street use.

The Crower 19212 is not an ideal cam profile for a turbo application on a 300 six.
The exhaust duration should not be more than the intake.
If you are going to use a restrictive stock log exhaust manifold it would be best if the exhaust duration was less than the intake duration.
Crower will custom grind a turbo cam for you.
 
pmuller9":2k2019it said:
if the heads are not ported and without an intercooler, at 6 lbs of boost and 5000 rpm
the pressure ratio will be 1.4 with 30 lbs/min of air.
If you run a good intercooler the airflow could go to 35lbs/min.

The GT3076R would be the better match.
Spool up time is determined more by the turbine housing A/R.
You have a choice between .63 or .82
The .63 will give much better low rpm spool time for street use.

The Crower 19212 is not an ideal cam profile for a turbo application on a 300 six.
The exhaust duration should not be more than the intake.
If you are going to use a restrictive stock log exhaust manifold it would be best if the exhaust duration was less than the intake duration.
Crower will custom grind a turbo cam for you.
The head will be ported and an intercooler will be added, for sure. My plan will be, should I proceed with a turbocharger, to have it dyno tuned to get the most boost and timing without detonation, because a dyno chart will see detonation a lot easier than I can hear it.

I'm glad you agree with me that the GT3076R would be a better match. That was my belief but I'm completely new to the turbo world. I'm just tossing up the pros and cons of a .63 and .82 A/R and trying to decide on one that I'll want, but from what I've been reading online it sounds like the .63 is the way to go.

What would be a good cam spec, do you know? Cams aren't that expensive. I'm willing to buy another one.
 
carbureted":d5be2rwg said:
The head will be ported and an intercooler will be added, for sure. My plan will be, should I proceed with a turbocharger, to have it dyno tuned to get the most boost and timing without detonation, because a dyno chart will see detonation a lot easier than I can hear it.

I'm glad you agree with me that the GT3076R would be a better match. That was my belief but I'm completely new to the turbo world. I'm just tossing up the pros and cons of a .63 and .82 A/R and trying to decide on one that I'll want, but from what I've been reading online it sounds like the .63 is the way to go.

What would be a good cam spec, do you know? Cams aren't that expensive. I'm willing to buy another one.
A cam with a 210* intake and 202* exhaust duration on a 212* LSA, valve lift around .450" would give you full boost from just below 2500 past 5000 rpm.
The intake lobe center would be set at 108* ATDC
I wouldn't go with any less intake duration without lowering the compression.

You should be able to run at least 10 lbs of boost with proper timing control.
That should put you around the 400 hp range.
It would be a shame to waste the power potential of such a good quality turbo using only 6 lbs of boost anyway.
 
pmuller9":1c1mjzos said:
A cam with a 210* intake and 202* exhaust duration on a 212* LSA, valve lift around .450" would give you full boost from just below 2500 past 5000 rpm.
The intake lobe center would be set at 108* ATDC
I wouldn't go with any less intake duration without lowering the compression.

You should be able to run at least 10 lbs of boost with proper timing control.
That should put you around the 400 hp range.
It would be a shame to waste the power potential of such a good quality turbo using only 6 lbs of boost anyway.
I only figured around 6psi because that's what I thought would be the safe zone, but like I said I'll do what I can to crank it up as much as possible while maintaining proper, safe combustion. I'd happily have 10psi if I could get away with it. Thanks for the help. I'll contact Crower.
 
I'd happily have 10psi if I could get away with it.
Since you are going to use an intercooler you can

And a Holley throttle body EFI (boost compatible) that I have yet to buy.
You must be looking at the Holley Terminator EFI where you have to download the HP software to make it work for boosted application?
 
pmuller9":12dyqga1 said:
You must be looking at the Holley Terminator EFI where you have to download the HP software to make it work for boosted application?
Yes, exactly. It is a free software upgrade which allows the computer to operate under a boosted application. The FAST self-learning system is incompatible with boost.

pmuller9":12dyqga1 said:
A cam with a 210* intake and 202* exhaust duration.
Is this @ 50?
 
carbureted":32tvyemk said:
Yes, exactly. It is a free software upgrade which allows the computer to operate under a boosted application. The FAST self-learning system is incompatible with boost.

After the upgrade will it still be self learning?
The reason that I ask is because the HP software is user programmable only not self learning.

FAST felt that it was too risky to have a self learning program try to cater to boosted conditions for both turbo and supercharger applications.
So this year they added the User Tunable XFI Sportsman unit that will work with their throttle body injection.
It's good for up to 5 bars of boost.

It would be better to go with the full blown Holley HP unit and use it with their throttle body.
You get Data logging, boost control, distributorless ignition, water/methanol injection control, rich/lean safety shut off ....ect.

I personally would go with their HP universal port injection system and mount the injectors on the Offy C manifold.
Then you wouldn't need to heat the intake manofold.
You also get to do sequential injection with individual cylinder tuning.

One of my favorite reasons to do "coil on plug" ignition.
It eliminates distributor phasing where the rotor needs to point directly at the cap contact at full boost timing.
I've spent many hours modifying distributors for this reason.

carbureted":32tvyemk said:
pmuller9":32tvyemk said:
A cam with a 210* intake and 202* exhaust duration.
Is this @ 50?

Yes, that's at .050"
The .006" or advertised duration should be at least 56* more. This is the minor lift intensity.
It effects the DCR and also how easy or harsh the valve is lifted and set back down on the seat.
So your looking at 266*/258* minimum.
 
pmuller9":4s5mywsb said:
I personally would go with their HP universal port injection system and mount the injectors on the Offy C manifold.
Thank you so much for mentioning the existence of this kit. I'd actually always wanted to do a multiport injection setup but I didn't think it could be done at an affordable price, but this kit is the same price as the TBI setup. I really like the idea of the better fuel distribution and especially the forgone need to heat the intake manifold.

pmuller9":4s5mywsb said:
One of my favorite reasons to do "coil on plug" ignition.
It eliminates distributor phasing where the rotor needs to point directly at the cap contact at full boost timing.
I've spent many hours modifying distributors for this reason.
Is there a good writeup somewhere of how to swap over to a COP setup?

I just want to take the time to thank you for all the help you've given me so far. It means a lot.
 
carbureted":2qrrgd5n said:
Is there a good writeup somewhere of how to swap over to a COP setup?

I just want to take the time to thank you for all the help you've given me so far. It means a lot.
There are 3 basic coil arrangements for a distrbutorless ignition system and all 3 are supported by the Holley HP system.

The first would be 3 twin tower coil packs where each coil fires 2 plugs at a time, one plug at the start of the power stroke and the other cylinder 360* away during it's exhaust stroke or what is called the waste spark.
This arrangement doesn't need the cam sync signal to identify when cylinder#1 fires.
Dodge Hemi, Ford and others.

Then there is the near plug coil like on the GM LS engines that normally mount on the valve cover.
You would need 6 coils and a cam sync signal to identify which coil is cylinder#1.
The LS2 truck coils are more powerful and are identified by a visible heatsink for the driver transistors.

Last is the coil on plug that simply mounts on the spark plug connector. No plug wire.

In all 3 cases 12 volts is supplied to the coil driver which is part of the coils and the HP system simply supplies a 5 volt trigger pulse.

There are several ways to supply a spark trigger signal and a cam sync signal for sequential fuel and/or spark control.

The most accurate is to mount a 60-2 tooth wheel to the harmonic balancer and a sensor.
The cam sync signal is then generated by grinding off all but one of the reluctors in the distributor and timing it to 60 degrees before TDC for #1 cylinder.
 
There is a great post by "thesameguy" in “Electrical, Audio, and Electronics “ section with the details of his build of a stand alone EDIS system (Wasted Spark) for his small block Ford six. Maybe it will be of some help, Enjoy :nod:

viewtopic.php?f=7&t=67718
 
carbureted":f4ydpuba said:
Which system would you suggest?

I would take a look through a wrecking yard for a LS2 system 2005 and later.
The Gen IV engine coils 2005 and later have more output than the former Gen III LS1.
If your lucky and find a 2005 and later Vortec truck engine with the coils that have the visible finned heat sink, those coils produce the most spark energy.
Vortec engines also include Cadillac Escalade and GMC Yucon Denali

Grab the coils, mounts, wire harness and the 60-2 crank wheel and sensor.
 
pmuller9":2dvq6n1m said:
carbureted":2dvq6n1m said:
Which system would you suggest?

I would take a look through a wrecking yard for a LS2 system 2005 and later.
The Gen IV engine coils 2005 and later have more output than the former Gen III LS1.
If your lucky and find a 2005 and later Vortec truck engine with the coils that have the visible finned heat sink, those coils produce the most spark energy.
Vortec engines also include Cadillac Escalade and GMC Yucon Denali

Grab the coils, mounts, wire harness and the 60-2 crank wheel and sensor.
When it's not so frozen out I will go have a look. Thanks.
 
For the cam sync signal, would I have to do something like the user in the Ford EDIS link posted above, or do you have another idea?
 
carbureted":2uggve7g said:
For the cam sync signal, would I have to do something like the user in the Ford EDIS link posted above, or do you have another idea?

Use the Duraspark distributor that has the 6 reluctors.
Grind off 5 of the reluctors leaving just one.
Remove the mechanical advance and lock the plates together.
If you want to remove the vacuum advance just for looks you will have to find a way to lock down the breaker plate.

Make a cover to replace the distributor cap just for looks.
 
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