406 head comparison E-TEC 200 vs AFR 220
 

I was looking to pick up some power on my street driven 406 6-speed 1988 Firebird (I know it is not a Vette but the engine management is the same so it applies). My goal was to have the same street manors as the current combination (Car drives great, good power, nice street manors, good gas mileage 22+ MPG on highway with the air on) and run mid 11's in the 1/4 at 116+ MPH on a 80 degree day. The current car (E-TEC 200 heads) has run a best of 12.00 at 114 MPH in good weather. The engine combination is as listed and is the same between both tests besides the head change:

-406 SBC
-10:1 compression
-Comp cams 280 XR HR13 cam 280/288 230/236 @.050, .576/.570 lift on a 113 LSA
-3" MAF sensor
-1-3/4 LT headers to a single 3" exhaust (No room in this car for dual)
-HSR intake for vortec heads with E-TEC 200 cylinder heads 64cc
-HSR intake with 1206 port for AFR 220 cylinder heads 65cc, competition ports
-6 speed car
-Pump gas

I am of the belief (general statement, other factors do come into play) that the better flowing the head, is the more power you will produce. I am also under the opinion that it is hard to get too big of a head on a 406 CI engine, it needs as much air as you can feed it. That being said here are the results of my head swap.

All numbers are rear wheel readings:

The head swap netted me approximately 70 RWHP (374 vs. 444) increase and a 30 RWTQ increase with almost no low end change in power. I have attached the dyno runs with comparison runs layed over each other.

Just some observations about power left on the table. My 3" air intake is too small, I had 2.8" of vacuum in the intake at WOT. My exhaust is too small the dual headers that dump into the single 3" exhaust pipe had 6.5 PSI of back pressure. Some day in the future I will change these two restrictions and I expect to see another 30 RWHP increase.

Thoughts?
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Yes....


WOW! I'd expect 70 hp increase over STOCK heads...but 70 over an aftermarket, 200cc head is incredible, IMO!


WOW...that is a lot of restriction! Wow.


WOW, again! That is a lot of back pressure! I can't believe your engine is putting down 444 to the wheels on a Mustang with those limitations. I have no doubt that you'll pick up a large gain w/an exhaust and intake. It will virtually be like adding FI to your current set up!

Over all thoughts? Killer gains. I agree w/your thinking on heads, but the gains over another aftermarket head are fantastic. :thumbs:

Love the scientific back to back, heads-only comparison

Thanks for sharing.

That is an unbelievable amount of back pressure.

Yes, I think you are correct in where the bottlenecks are.

That is an impressive increase! Very nice and thanks for posting the results with actual data to back it up.

IMHO, switching to afr heads on an ltx or sbc (and getting rid of the crappy l98 intake) negates the benefits of an lsx swap.

Agree, that is a huge gain and knowing theres more on the table if you feel like getting after it....theres some oval almost flat exh tubing thing 1989 transam has it on his but can be pretty pricy.

Glad you posted this, good info for all sbc guys Vette or not.
Would love to trade in my Darts some day for some AFRs...or a new head that Tony has out (its friggin:crazy: insane).

We live in a great era of tech where one can make outstanding power with a sbc....growing up getting 400hp out of a 350 required quite a bit!

Nice job!:thumbs:

Awesome. Shows the AFR220 can really flow some air.

Jim will love to see this.

Lot of gain off the head swap. Gotta love the 406. Ron, what new head is Tony cooking up?

you realise that as an Edelbrock head owner you have made me very sad ! :lol:

how does it drive on the street after the change ?

Thoughts? Great results!! And thank you for sharing info that BELONGS in C4 tech and performance!! 100% agree that a better flowing head will make more power, all things being equal.
Btw, back in the late 80's I had a 82 Z/28 with a 415" motor. I managed to run to 3" pipes down the passenger side tunnel stacked one on top of the other. Went over the axle and had the double offset mufflers stacked. Sort of mounted like the stock tranverse muffler with both pipes exiting on the drivers side rear. Looked like a V6 exhaust on steroids with 2 3" tailpipes. IDK if I still have any pics though.

Very nice Brian! We will have to line them up at WIR again. I might have to borrow your tires to win from now on!

The car drives well, it has an aggressive idle but as soon as you are off idle it is fairly smooth. I cruise at 60 mph in overdrive at 1450 RPM and the car drives well.

Yeah thats a nice cam but alittle small in a 406 imo but with great heads and intake small cams work.
I would have guessed 50 hp but 70 is really great! The 220 head is a great street strip head for 400" motors! Just shows how weak the etec 200's are in stock form on large motors. Tired of seeing big motor builds and people using typical 190-200cc small heads. 210-227 works great for big inch motors

So what is the max size head for a 383ci LT-1 with 224/230 duration and 530 lift 112 lsa. ? I would like to get at least 500 hp at the motor. I have port matched stock heads with 2:02/1:96 valves and mild bowl work, springs, roller rockers, etc. I know I am falling off hp at higher rpms. Is my cam large enough for 200cc + heads?
drive train is built 4l60, 3,000 stall and dana 44 with 3:73's.

I had AFR 195's on my 383 LT4 with a 233*/236* cam and it pulled hard all the way to fuel shutoff at 6800 rpm if I wanted it to.I could have made more power with more cam and larger heads but it was a street car and manners played a part in my choice.

I agree with you, I picked the cam because I drive the car every day 50 miles round trip to work and I wanted something that drove well but still had good power. This cam fits that bill, sure it could have been bigger but I wanted a smooth easy cruising combination. My other cars have the wilder cams and more aggressive combinations, but they are not my daily driver.

Nice work Brian. I am glad to see the AFR's work out for you.

Thats a fun drive to work!

Dyno sheet oughta leave a few scratching their heads (says 350 on it) :thumbs:

That was the combination when I first dynoed the car back in 2008 on that dyno. Since then I have made a few changes!