for my forged 357 build i am considering RHS heads. i *think* i want to go with iron heads so i dont have to worry about heat soak considering this will be a drag car.

the pistons are flat top with valve reliefs and from my calculations 10.5:1 SCR with 64 cc heads. although i am not sure about deck clearance.

http://www.racingheadservice.com/Inf...hevy_200cc.asp

i am looking at the 200cc heads and i am intrigued by the heads all having Comp Cams components and at the price of $460 a head.

http://store.summitracing.com/partde...&rsview=sku&Ns=

the cam i am going with is has .504/.498 lift with 1.5 Rockers (i will be using 1.7's) with duration at .050 of 247/254 and adv duration of 284/291. the cam is solid flat tappet.

with the 1.65 the lift goes to .554/.548 and the max lift on the heads is .560. the flow would be about 26X/158 CFM int/ext.

any thoughts? they flow better than Dart's iron heads as well as brodix's iron heads, but not as much as the AFR 210cc's so what do you think?

 

RHS has great numbers, but the Dart IronEaglePlatinums have wet-flow that's proven to make more power from the same airflow. Platinums aren't as cheap as the RHS, but I'd go Platinum. And I feel the weight does offset the heat soak, which I feel you have backwards anyway. So I'd go with the Dart Pro1Platinum 200s, unless I was using nitrous or boost, then the AFR's superior exhaust flow would matter more to me.

 

according to both manufactures websites the RHS heads flow better than the dart heads and dart is not showing the conditions that the heads are measured on the flow bench... how mauy in Hg? what size bore? etc.

its not the cost that is most importiant. i will keep the dart heads in mind though. also i do not know what components that dart uses in their head, and i like the fact that RHS uses all comp cams components.

but i am still open for further suggestions.

 

Dart uses 50 for r&d, then 28 for what to publish. If you want all comp parts, buy the darts or AFRs or whatever, bare.

 

the weight definitely makes a difference, but i have already shed a lot of weight in the engine bay with no a/c p/s smog junk/ and various other things.

the reason why i am concerned about heat soak is that my maro has a flexalite fan ran by the water pump and turning it off in between runs makes it more succeptable to high temps than if i was running an electric fan.

you may feel as i have it backwards, but i am not sure if i think i am.

 

i was looking into the details of the flow bench test and i think the darts flow better due to the fact that at RHS heads were tested with a 4.200" bore and the darts are at 4.030" bore and the numbers are close.

i could also up my Rocker ratio to 1.7 or 1.8:1 and get about .60X of lift on both sides of the dart which that amount of lift is not compatiblle with the RHS heads. and the darts are also dual valve spring as opposed to single.

so now i really dont know...

 

any thoughts on the flow with the different bore sizes as tested?

 

I have purchase RHS 220s, and had them flow benched by a local guy here in town, and beleive it or not, they flowed better than advertised! They actually flowed just a tad less than adv. at low lifts, but well above the adv. numbers at high lifts, so I must say that I am very impressed with RHS so far!

 

thats good to know. what is the rest of your setup?

 

Just get the heads setup with the right valve springs for the cam you will be running. As long as the spring has the pressures needed to keep the lifters on the lobe at all rpms you'll be running, and can handle the lift, you'll be good to go.

Whether you go iron or aluminum is up to you. I love aluminum's weight advantage...thats 50lbs difference which is helpfull and can add up when combined with other weight losses to give you some free ET

Anything over 10 to 1 compression with Iron may not be pump gas friendly, so you'll want to mix in some race gas or run race gas. May not be a problem for a drag build but pump gas is nice to have since its so much cheaper and available everywhere. Aluminum at 10-11 to 1 compression can run fine on pump gas and probly make as much or near as much power as that iron headed motor. Being abit lighter it may run abit better too. If you get a good aluminum head that flows more than the irons, it probly will make more power than the less flowing iron head that needs a mix of racegas or much less timing to control detonation. Thats a bonus in getting a better flowing aluminum head at those compression ratios.

Depends on what your budget is and etc. RHS does have some good heads. 200cc and that cam will do well.

 

now looking at aluminum heads, that puts me back to AFR because the set of

RHS 220CC aluminum heads costs $1200, and the

AFR 210 eliminator are only $1500
and that is what i was initally thinking going with AFR and their reputation is probably one of the best in the racing world.

but if i go with the 220cc iron RHS i am under a grand and could put that $500 into something else.

 

How fast are you intending to go? How high rpm do you want to turn? A 200 cc head should probly be all you'll need with that setup. That cam is a nice sized cam, but AFR210's or RHS 220's on a 357 should be for setups trying to turn abit over 7K rpm. I think that setup would be done by 7K or so rpm, depending on what intake you run and such.

AFR 195's or RHS 200's would be up to the task of feeding that motor to 7K. AFR 195's have fed my 383 to 6800 rpm no problem, and the older style 195's have fed my buddy's 406 to near 7K as well. My car went mid lower 11's all motor and my buddy's 406 went high 10's all motor

 

i am definitely winding it up to 7k, the 195's or 200cc's would do the job, but i think i am going to do some spraying so i am not totally sure.

 

I just think you'll be giving up too much on the low end which will hurt your off the line performance. 195-200cc would give that back and make that car strong off the line but still have solid top end. 210-220's are much better for larger motors

whichever ones you get, just make sure they have the right valve springs for your cam. Nitrous wont make too much difference on head selection. Spray away

 

i think i will go with the RHS 200cc heads.