jean

Hi All!

I have those sportsman 2 heads on my 355 chevy engine and I've read that on Jegs Site , Is it not a little optimistic?? What difference in HP brings a porting job on those heads??

Thanks lot

" Typical Application Street: 274 Cam: 230/236° .487''/.490'', Dart II Sportsman #955-061010 dual plane intake; 750 cfm carb, 1-3/4'' header. 430HP on 9.8:1 355; 480HP on 383 10.5:1 (varies with displacement and compression ratio).

cmack

those heads are really good and those hp numbers sound about right. the heads have 200cc intake runners and a porting would make them even less street able the heads flow good right out of the box

jean

Thanks for your answer

I've heard that the porting would help on the exaust side as it was the weak point of those heads , right or wrong??

cmack

it definitely will help on the exhaust side i wouldn't do much to the intake i've worked on a couple sets of these heads and they are pretty good but a deburring wouldn't hurt

jean

Hi,

I've also heard that to much flow not matching the engine size would be worse , so for a 355 and a 274 cam would I have benefit of porting those heads?

85Firebird350

iTrader: (3)

I have a set on my 406 with a custom cam making 574flywheel hp and about 530rwhp. Mine are ported polished and milled down to 63cc chambers.

customblackbird

iTrader: (15)

i read that the sportmans II's where good over a decade ago... but todays standards they are outflowed by a set of stock vortecs. the large 200cc runners arent efficent... not even as much as a set of vortecs. still the sportsmans are better than stock iron heads but todays aftermarket aluminum etc flow much more than them. again this is what ive heard. porting would prob help if u knew what you were doing and depending on ur setup.

on a 350... normally a 200cc head is exteme... cam and heads would have to peak at 6500-7500rpm

on a 383 195-210cc heads are normal and peak pwoer with cam should come in anywhere from 5500-6500.

anyone know the flow #'s on the sportsman II heads????? cuz i would love to kno so i can figure out if what ive heard was wrong. do they even have heart shaped combustion chambers?

jean

What I've read is all opposite...Sportsman 2 are still in the game and still better then the Vortec eventhough those are definitely the best stock heads out there.

85Firebird350

iTrader: (3)

I've heard nothing but good about them too, they come with fastburn combustion chambers now and I know mine flow like this...

LIFT VALUE
INTAKE FLOW CFM
EXHAUST FLOW CFM

0.100
68
53

0.200
144
106

0.300
206
144

0.400
242
173

0.500
252
195

0.600
257
205

jean

Ya not bad at all and putting out 430 hp on a 355 don't know wich heads would do much better on same kind of set up ....

customblackbird

iTrader: (15)

430hp with a 355 with 200cc heads.... isnt all that great... stock vortecs ive seen put out 430hp on 350s... and the lower 170cc runners will make a but load more tq.

those flow numbers arent that bad actually. i got a set of patriots 195cc that flow alil but more. 260's at .60 and 270's at .70 lift.

maybe it was an older casting... of the sportsmanII's...idk

85Firebird350

iTrader: (3)

Well my motor makes 575 hp on a engine dyno so I'm happy with the numbers and of course everything is matched perfectly with the cam so that helps a bit too.

customblackbird

iTrader: (15)

wats ur setup for 575hp?

im going 383 HSR (Ported, portmatched to felpro1206)
comp cams XFI280 230/236 .567/.571 113lobe
patriot 195cc heads 266cfm at .60 lift, portmatched to felpro1206
1.6rr
30lb SVO ford injectors
58mm TB
custom tune
grannelli maf
yadda yadda yadda.

they say 480-500hp. im hoping for that too...

85Firebird350

iTrader: (3)

406SBC
Holley 750HP series carb
Edelbrock Vic jr. manifld
Custom grind Compcams retrofit Hyd. roller .585/.599 lift 238*/248* dur @.050 113LSA
Crane Retrofit Lifters
Crane Hardened pushrods
World Products Sportsman II's ported and polished, angle milled, setup for roller cam with .700 lift
12:1 compression

jean

Would I get a real benefit to have my sportsman 2 heads ported on my 355?

85Firebird350

iTrader: (3)

I would think so, go out and buy a pair used and put the rest into porting. Take this like a grain of salt but my SP2's out flow by buddies ported TFS aluminum heads..

customblackbird

iTrader: (15)

u musta really ported the hell outa those sportsmans. u flow alil less than my patriot 195's on the intake but u flow about 10-15cfm more on the exhaust. theres no way they flow like that outa the box... thats all on your porting.

im hoping that u got 75hp more wit that 12:1 comp, u have more duration on ur cam along wit lift.... i wonder if thats 75hp... im convinced i should be gettin 500hp now lol

85Firebird350

iTrader: (3)

Well I get more HP for the bigger bore and more cubes, higher compression and yes the heads were ported pretty damn good,. It's a $1200 port job with the most work on the exhaust side to take advantage of my hooker 2210's. The cam also helps since its matched perfectly to the combo from COMP.

RU-QWIK

iTrader: (3)

I have a set on my 355 and they are heavily ported...Same as above, 1200 bucks in the porting, but they flow very well and the car makes plenty of power. Years ago, I drove the car daily, it runs good, gets great gas mileage, etc... They guy that built my engine and ported the heads advised me against buying a new set of AFR heads, said they would be a waste of money since my heads flow as good if not better. He flowed them but I don't remember what the numbers were..311cfm is all I remember, don't remember any more. I may call him to see if he saved any info...doubtful, it has been years.

Jason

85Firebird350

iTrader: (3)

311CFM? Thats more than AFR 210cc race readies... Mine dont flow nearly that much but would only gain about 25hp switchting to AFR's so I went against them. The new engine being bilt will be AFR 227's though

RU-QWIK

iTrader: (3)

Yeah, the flow sounded high, but he has a flow bench, worked for AFR many years as a porting tech. and now only builds high end race engines. He built mine only because we are friends, it is a very nice engine, but nothing like he usually deals with. I am curious now as to the numbers, hopefully he still has some info....

http://www.geocities.com/jasonsz28us/Pic8b.jpg

Jason

85Firebird350

iTrader: (3)

That port looks hogged out to nothing, good stuff. I want to get myself a pair of the motown 220s next

customblackbird

iTrader: (15)

yea i figured the cubes etc but wow the exhaust on that head looks great! i portmatched my patriot 195s to the 1206 that they require along with the HSR. but they said not to port and polish the intake runners bc the gas/air mixture likes to me swirled by the rough casting...mixing the gas/air better. once in the chamber it doesnt matter anymore. is that true? patriot hand ports the heads for the flow (half way up the intake runner is reallly hogged out, but very lil on the exhaust) and does CNC bowl work, i got the dual spring upgrade thats good for roller cam up to .670 lift, 5 angle valve job, vitton seals, stainless swirl polished valves. bc i would like to hog it out alil more if i could especially on the exhaust side. since mine dont flow as well as your 1200$ port job on the exhaust side. and im sure i can pick up a few poines with exhaust porting.

here are the patriot 195 flow #'s by skip whites flow bench.
starts at .4 lift
intake/ exhaust
.4) 223 / 170
.5) 252 / 183
.6) 263 / 184
.7) 270 / 185

85Firebird350

iTrader: (3)

I would think you could port out the exhaust side to get some more power. You can port the intakes but you do need to leave it a little rough.

customblackbird

iTrader: (15)

where would i port the exhause port? they already opened up the bowl area about 3/4" inside the exhaust port right behind the valve.... i dont wanna take the valves out either lol

bk2life

ever finish this combo?

customblackbird

iTrader: (15)

yea, ran it for 3 months and the car was stolen and gutted the power train. So I don't really have any idea but it ran strong.

QikNick

I run Sportsman 2 heads and have for years. They are on my current combo floating around 600ish horsepower. These heads respond extremely well to porting. Id put mine up against anything out of the box. Mine are heavily worked and you must know what your doing or you'll create dead spots and kill velocity. Mitchell put alot of meat in these heads with the intent the end user would rework them. Valve bowls are terrible out of the box but have awesome potential. I Love mine! Just my .02