Hey guys
I was always under the impression that us turbo guys don't need to spend lot of money on porting heads and manifolds etc like you would on a NA engine.
I'm running out of the box edelbrock rpm performer heads. While my engine is a part will it be worth me spending money on porting the heads or would I just be throwing money away as I can just turn up the boost.
Is there any advantage to porting the heads on a turbo engine or would it only gave me a few extra horsepower.

 

Anything that makes more hp in na form will make more hp in boosted form, but as you make more hp na, your turbo needs also change. If you can make your desired hp on reasonable boost, theres no need to port.

 

I'm making 650 to the wheels on 15psi on a 9.3 compression engine. Once I have rebuild my engine with forged internals I would like to bump it to 20 psi max to see what I can make and leave it at 20.

 

Just run the boost up.

 

Do you have a horsepower goal in mind? Head porting increases in value as the horsepower goal rises.

 

Just as a bench mark, Chief is running a basically stock width Edelbrock port and manifold system (vs a wide port E-Head).
Everyone knows how fast he has gone on methanol and how many races he has won over the years against 600 cid BB Chevy
turbo engines with much higher flowing heads. More to it than just port airflow with a turbo engine.

In 1996 a Pontiac Guy went 6.95 in the quarter with a 240-260 cfm intake port cast iron head on methanol. You planning on running 6s?

Tom V.

 

6s down the quarter. Now thats fast. Im not planning on going that quick.
I'm currently 645 horsepower at the wheels with 15 PSI
I won't run 20 psi and was hoping to push the horsepower up as much as I can with the extra 5 psi. As you know boost is a measure of restriction so my thinking was if I ported the heads it would
take less boost to make the same power.

 

That's a good reason to do the porting

 

The gains aren't always big enough to make it worthwhile though. If you follow Matt from Sloppy Mechanics, he did a dyno test of cnc ported heads on a 5.3, and the gains weren't worth the cost for most on a forced inducted engine imo. If you're looking to make the most hp on low boost, or max out a combination, it's probably worth the effort, but if you have room to up the boost and make your goal, I don't see it as worthwhile/cost effective for many.

That being said, I do plan to pocket port my latest build because I have the heads off and apart, and I have ported plenty in the past so it won't take long....and its free.

 

I've got a few prices back for porting and I'm starting to lean that way myself. Cost of porting is a lot more than I thought it would be. Considering last time I was tuning I was adding 1 psi and pulling out 1 degree of timing and getting 30 horsepower gains each time.

 

I don't think a blanket generalization can effectively be made regarding the original question because the answer is largely dependent on the cylinder head. "Performer RPM heads" doesn't quite tell the whole story. Being that the OP is working with LA Chrysler cylinder heads, I respectfully submit that even basic DIY porting would be worthwhile considering that LA Chrysler Performer RPM heads leave quite a bit on the table in terms of performance potential. They're not a bad casting, but they can be *significantly* better with even just minor clean-up work, gasket matching, and a proper valve job as compared to out-of-the-box.

The standard width Pontiac E-head mentioned earlier is an animal compared to the LA heads, especially if comparing output potential on similar displacement engines such as a 406 Pontiac versus a 408 Chrysler, which, if I'm not mistaken, the OP intends on building. Without a bit of work, the 408 is going to hit the choke point of that particular Edelbrock casting very early relative to RPM and mass air flow through the engine, which, in my mind, translates to less HP-per-pound of boost in a forced induction application. If gains can be had via porting, particularly in the mid-range, that end up requiring less overall boost pressure and that provide an even wider window of both tuning and power potential, why wouldn't those gains be pursued?

Also, Marty's iron heads were well prepared all things considered. A Pontiac iron head doesn't go 240-260 cfm with just touch-up work. Further, and I know Boost Engineer already knows this, but I think it's still worth mentioning; 240-260 cfm through one intake port model is not the same as 240-260 cfm through another intake port model. I get the point of mentioning Marty's heads and the performance they helped provide, but I still don't think it's an entirely helpful comparison (respectfully, of course... Boost Engineer is both more intelligent and more experienced than I could ever aspire to be).

 

I agree 100%, some heads respond to porting much better than others, and dated cast iron heads probably are right up near the top in % of gains. There is also something to be said about matching heads to the build as well. You can spend plenty on reworking what he has (given you can't do the work yourself), or buy something that's better suited. Porting and head work isn't a bad thing, it's just expensive, and can easily be messed up if you're not sure what you're doing.

 

I have seen big flow head numbers that did not work that well in a NA application.
A Boosted engine just has a higher density charge going into the engine vs the NA engine.
ALSO BECAUSE OF THE HIGHER DENSITY CHARGE the Push on the piston/crank assy is for a bit longer and that helps the torque
capability of the engine. Corky Bell in his books explains this very well in easy to understand terms. Well worth reading his books on
boosted engines.

There are people out there who do not understand any of the math that can port a cylinder head that will make 1600 hp with boost.
I had the pleasure of watching a gentleman port a Pontiac Head (he did Martys heads) and he knew in his brain what the port needed to look like and he ported heads exactly the same every time. Just like a cnc machine but a human. May he rest in peace. His heads did not flow big numbers (like I said 240-260 cfm numbers) but they were good enough to make 1600 hp with a 406 engine and higher boost levels.
A different example, a guy with a Pontiac 455 2-bolt main engine and edelbrock "lower compression heads" made 863 hp at only 13 psi of boost pressure.
Those heads were 300 cfm heads. No way was he going to ever need more hp than that on his street car. There are Race Cars run on the street and there are street cars that make good hp on the street. At some point the $$$$ to get the power to the ground costs more than the engine costs.

I am not against porting a head, I am just saying that a 600 cid engine with boost is not always as fast on the street as a 482 cid engine with a good chassis and boost on the street. A guy named Chief proves that point every week on TV. Boost is just one of the players on the 'Team"

Tom V.

 

My time at Underground Racing taught me a few things in this regard. I had been in 1200 hp Dodge Vipers that would smoke the tires from a roll at 100 mph, and I had been in 1700 hp Lambos that would completely eat from a dig due to the AWD. Before the Lambos they were stroking 8L v-10's and using lots of meth to hit 1500. Now, they're well over the 3,000 hp mark with a 5 liter and 5.2l v-10. Smaller engine, but a lot more airflow capable. Stock, the lambos are in the 500-600 n/a range.

Airflow and traction will trump most anything.

 

Its a way to squeeze more horsepower out of what you have by making it more efficient .Remember that an engine is an air pump .and the more air you can squeeze in there the better,

 

But... If you're close to the limit of your compressor you could push it off the map. In that case it's probably better to up the boost. Anytime you change your na hp by a decent amount, you should be looking at your turbo choice as part of it. If you're over turbo'd its not really an issue, but the op isn't imo.

 

What is the current setup and budget like? Many times you gas out the turbo with a good port job as well and end up running out of steam early. For a mild setup like yours, a professional port job isn’t worth the $ vs HP gained in most cases IMO. Esp. the “CNC” programs.


A simple DIY home port job is usually worth 10-20HP (crank) depending on your skills and the head. That gain roughly doubles for each 15-16lbs of boost you run. So IMO it’s worth grabbing some cheapie china burr tools and watching a YouTube video or 2 and mildly porting what you have. Don't go overboard and take your time.

 

Very TRUE words there.
That being said, you really do not want to:
1) Just copy what someone else did unless you have the same budget they have or a larger budget.
2) Assume that after you built this "killa" Turbo Set-up that you will be happy at say 12-15 psi of boost.
(The 4 cylinder Pontiac Guy started out at 12 psi and eventually was running 39 psi of boost. This was
after several upgrades on parts.) Engine Parts, Transmission parts, EFI parts, intake manifold revisions,
different camshafts, different turbos, different header design, etc
The only thing he basically kept were his EFI system and his Inter-cooler system.

TURBO CARS AND ENGINES ARE AN ADDICTION.

Tom V.

 

AWD is like training wheels you take the training wheels off and they’ll be on the next car fail video on YouTube lol

 

You might want to try driving an Evo or a WRX on street tires from a dig or a slow roll, and that makes an honest 800+ WHP (let alone a 2,000+ WHP Lambo) to better inform your opinion. Sure, AWD is advantageous, but those cars can still be a handful and still require driving talent.