351w Combo Advice

[4SPDFOX...+1]

Current setup:

.040" over 351W block
Fully balanced rotating assembly, stock crank and rods
KB 151 pistons
Everything CC'd, ACTUAL compression came out to 10.1:1
C9OE 351W heads- stock on the intake side with 140cc port, exhaust port "hogged", looks huge next to an E7, aftermarket stainless 1.84/1.60 valves, Comp springs, 97 lbs on the seat
Stock 5.0 HO roller cam
Howard linkbar lifters
TF 1.6 roller rockers
RPM intake
Eddy 800 cfm carb
Short tubes
Full O/R exhaust
T5
3.55 gears

Made 298hp/328tq to the tires

Doing head/cam swap real soon here. Seeing as mine are basically stock, i'll be looking for ~360rwhp. Cam will be Comp XE282HR with upgraded springs as well. Can't decide on heads. Thinking TW 170s? Want max power at 6,100 rpm so I can shift at 6,500 rpm. HELP!!!

 

[NIKwoaC]

You're going to want something bigger than the 170s. AFR 205s or TW CNC 185s both flow in the 300 CFM range at .600" and would be good choices. A TW 205 would also be great, too (315ish CFM @ .600).

There are lots of other good heads out there too, but I would be looking for something that flows high high 200s @ .600" as a ballpark starting point.

 

[4SPDFOX...+1]

I am just concerned that if I go big on the heads it will shift my powerband way up high. The bottom end is balanced but it is just a stock crank and stock rods with stock rods bolts. I like to shift after my power starts to drop off by a few hundred rpm so that when I hit the next gear I am closer to peak power again. I don't think I should take this engine any higher than 6,500 so my peak power will need to be in by 6,200. With the stock heads and cam my peak power is already at 5,400 and doesn't drop until 5,800. I am worried that 205cc heads will bring my max power to like 6,800 rpm.

 

[NIKwoaC]

If it were me, I'd put a nice set of heads on it and then cam it to get the RPM range you want. If you do it the other way around, you'll be kicking yourself if/when you build a bottom end that can handle more power and RPM, but your heads can't.

Just my thoughts, you can achieve your goals either way!

 

[98gtvert]

Love my Afr 185's. Pulls hard to 6500

 

[88LX5.Oh]

I'm with Nik. Get a nice set of heads THEN choose the cam. Most people go out and buy some ridiculous cam and then try to build around the cam, when what you should really be doing is choosing the cam LAST.

 

[hoopty5.0]

^ yep

 

[68stang351]

Don't be afraid of a bigger set of heads. On my 351w, I have a set of tfs 170's with a comp xe284 cam, and I really believe that I left some on the table by only using 170's. Keep in mind that the cross sectional area of TFS heads are larger than others of similar ratings, they are more comparable to afr185s. But I still feel I should have went with something around 205. This is why I have a set of Roush 200's sitting in the floor right now, lol.

 

[4SPDFOX...+1]

Thanks for the help so far. Heads have more of an impact on an engine's powerband than the cam. Stock 5.0 with aftermarket heads will make peak power at 6,000+, stock LS1 pulls to 6,500 rpm with a cam similar to stock 5.0 HO cam. If the heads make max power at 7,000 rpm, putting a 5,000 rpm cam in the motor will just kill the whole combo. I've seen it and done it. Want to pick heads that match the XE282HR cam and RPM intake, which are both rated to 6,500 rpm. AFR 185s seem to be a popular choice., but i've had ppl say they went 11.8x @ 117 mph with ootb TW 170s on a 357W. Compression will be 10.4:1 with whatever heads I get because i'm going with 58cc chambers. The ppl that are chiming in with thier own personal combos- keep it coming! Love to hear the numbers and trap speeds you are getting.

 

[4SPDFOX...+1]

What i'm getting at is I know what rpm range I want and the XE282HR is right on the money. It also has a great rep and made great power in a friend's 347. 6,500 rpm shift points, i'd like max power to be at 6,200 rpm.

 

[bentley429isBAC]

Atleast 205's, and get a custom cam. Figure out what you have to do to get to 11.5:1. You want longtubes too, shorties are a joke. Atleast 1 3/4" primaries and 3" collectors. RPM is a weak intake, look into a victor. Tranny is going to fall out and around a 3.90 gear would be a better choice.

 

[hoopty5.0]

Atleast 205's, and get a custom cam. Figure out what you have to do to get to 11.5:1. You want longtubes too, shorties are a joke. Atleast 1 3/4" primaries and 3" collectors. RPM is a weak intake, look into a victor. Tranny is going to fall out and around a 3.90 gear would be a better choice.

The short, unaltered truth. Maybe a little high on the compression though.

 

[NIKwoaC]

What i'm getting at is I know what rpm range I want and the XE282HR is right on the money. It also has a great rep and made great power in a friend's 347. 6,500 rpm shift points, i'd like max power to be at 6,200 rpm.

Choosing a cam first and then building an engine around it is like buying a key and then having all the locks in your house custom built to work with it. The cam is the glue that ties a combination of parts together to make it run the way you want it to run, that's why there are custom cam grinders that will develop one-off cams for you to get your combination of parts to perform exactly how you want it to.

Like I said, you can achieve your goals either way, but I think you're approaching it backwards.

 

[FastDriver]

Ask Nik about his combo. I get the idea that you're looking for low end torque which you will find with a long runner Intake and appropriate cam. Select heads based on displacement. You will be fine with a 205 - 225 cc Intake runner. Oh and btw. Peaking at 6200 is actually pretty high for a street motor.

 

[FastDriver]

Oh yeah. Forgot to tell you that my motor peaks at 6300 with a 228/224 cam even though I have a box intake and AFR205 heads.

 

[NIKwoaC]

Ask Nik about his combo. I get the idea that you're looking for low end torque which you will find with a long runner Intake and appropriate cam. Select heads based on displacement. You will be fine with a 205 - 225 cc Intake runner. Oh and btw. Peaking at 6200 is actually pretty high for a street motor.

Haha, after driving a 302 with 205s for almost 2 full seasons now, I can definitely say that heads this big are overkill for a mild mannered 302. Glorious overkill with 100 miles of growing room left, but overkill for the current state of my combo, nonetheless. That may change before next summer though. Anyway, I wouldn't hesitate to put them on a 357... In fact, I may end up doing just that.

Oh yeah. Forgot to tell you that my motor peaks at 6300 with a 228/224 cam even though I have a box intake and AFR205 heads.

Not to mention it's a 331 (a damn healthy 331 with gobs of boost to boot )

 

[FastDriver]

Whoops! yeah forgot to say that too. So you think you would drop to the 190s if you did it over?

 

[NIKwoaC]

Whoops! yeah forgot to say that too. So you think you would drop to the 190s if you did it over?

Nope, I would probably do it the same way if I did it over again, only because I know that I will eventually put that 319 CFM @ .6" to use by means of more cubes and/or boost. Like I've said before, the idea was to eventually "grow into" these heads, but with that said, they are blatant overkill for a sub-6500 RPM naturally aspirated 302. The car works just fine and is a solid runner, but I'm sure similar results could have been achieved with less cylinder head and only a little more cam. Or I could have just thrown a set of 170s on it, used the stock cam and my old Explorer intake and put a Vortech on it and went faster for about the same amount of money lol.

 

[FastDriver]

Cool. I'm happy with my decisions thus far, as well. Though once I get the entire car finished, I could definitely see myself trying different intakes to see what happens, or shooting for the moon with a solid roller and a suitable high revving intake like a victor. That's if I ever turn it into a race car, though...