s/r or 915?

[70gtx]

well i still cant make up my mind.i definitly need closed chanber heads to get comp/ratio up.i fould 915 ported, and all new for $1200 or s/r & $2000.problem is i have these trw's without reliefs so i probably wont be able to go more than .500-.540 cam lift.will i just be wasteing money on aluminium heads with small cam?will i be in trouble with cracking on 915 flowing
270/210.
car was headers ,hooker mufflers ,6 pack,3.91, com/ratio should fall around 9.5 to 1 with either heads ;.
any input would be appreciated. walt

[451Mopar]

If your on a tight budget, remember that with any of the aluminum heads you need to buy a head stud kit (about $100), and they may need special length pushrods that could add another $100 to the cost.

[70gtx]

not on a budget anymore ,wife said i wont be happy till i get it the way i want it so do it .i was just wondering if i will get anymore HP from aluminium heads with small cam.i fould new for 1799 + 250 for installation kit .

[72Challenger]

All else equal, you will get less horsepower with the aluminum heads, but it has nothing to do with flow. It has to do with the heat transfer properties of aluminum versus iron. The aluminum transfers heat much faster, thus drawing energy out of the combustion chamber. You need another 1/2 to 1 point higher compression ratio to offset this. As for flow, what you need to consider is flow at the lifts you will be using. Just because a head can flow to lets say .700 lift, doesn't mean it won't work well at lower lifts. Often times a head that isn't designed for super high flow will have better velocity and flow at the lower lifts. You need to graph the flow numbers of each head and compare the flow at the lifts you will be using. The flow at lift numbers will make a curve on the graph, and you want the head with the most area under that curve, up to the lift you will be using.

I think you need to start with deciding what sort of driveablity characteristics you want, then pick a cam to match. Then pick the heads that will flow best with that cam. Then see if your existing pistons will give you the right clearance and compression. If not, sell them and get ones that do. If you mix and match components based on trying to fit whatever you already have, you're not really chosing your components, you're having them chosen for you. You'll get the best results with matched components.

[Brian_wo]

Originally posted by 72Challenger:
All else equal,

The only thing about that is thats the SR's and the 915's are not equal,the SR is a much better head and for the little bit more the SR's are over those 915's you talked about it would be money well spent,this way some day down the road if you upgrade the motor you are port work away from a killer motor,now listen to your wife,you won't be happy till it's right,she's probably tired of hearing about the car huh?
As Herb McCandles told me,it's cheaper to go fast the first time.

[DartGT66]

If you are getting more power with 915's than with SR's everything else being equal, you must be Harry Houdini. It's true that Aluminum heads need more CR than iron heads, but at 15:1 you will amke more power with aluminum heads than with iron heads, simply because that's too much CR for iron heads. Alunum is also lighter and way easier to work on, that's why they are used in every serious race engines, and almost all modern production engines. I have used aluminum heads in the street for over seven years, and I can't understand what head studs has to do with aluminum heads? At least our Stage VI's stay on just fine with the stock head bolts with washers, and my Indys have bolts too.

[72Challenger]

I'm being misunderstood! I never said that his head choices were equal. I stated the fact that aluminum needs more compression than iron. What I was trying to get at is that 70gtx is limiting himself making his choice based on the pistons he already has. Yes the SR's will make more power than the 915's. But also, other changes should be made as well to get the most out of them. He never stated his goals, maybe the SR's are overkill for what he wants. I just wanted him to consider all the factors which go into a well-balanced engine package.

[DartGT66]

OK. Of course you have to make the engine work as a package, but a good cylinder head is a win/win situation if the port size isn't bigger and the velocity poorer. Although I have not used aluminum heads in under 10:1 engines, I must say that even the Stage VI's which are considered the worst of the pack gave a noticable improvement in performance compared to template ported iron heads. There was a cam change too, from MP 280/.474 to a custom mechanical 260/.510" cam but the CR remained the same; the ET of the 3600 lbs car with 3.23 gears went from 12.9/109 to 12.16/116 mph with regular 205/75/15 radials.

[440 Jim]

My 2-cents:
Look hard at that $250 installation kit. I believe buying the components separately is a better idea. The external oil line kit is only about $50 and the head bolts and pushrods are widely available. Especially the push rods. You may need/want custom length for your motor (decking, head milling, rocker gear, etc.) And you can pick the wall thickness, diameter, and heat treatment you pick rather than whatever is in the kit.

[ChristianCuda]

I think what was meant to be said earlier was that comparing the 915's and the S/r's with the same chamber volume that the 915 will have more compression thus more power due to the heat exchange on the aluminum heads becase both heads are at 65cc. If the S/R's had a smaller chamber volume then the S/R's would be better but that will also depend ont he lift of the cam and the valve notches in the pistons and how much you have to cut off the heads to up the compression that .5 to 1 point.
I think as long as he has 10:1 compression now that the S/R's will not decreas performance that much if at all but any less and you can expect a decrease. Figure it as if you were dropping compression 1 point. At 9:1 you will now effectively be at 8:1. At 8:1 you will effectively be at 7:1 (ouch)!

Christian

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Http://ThunderRacing.Knudstrup.net/

68 'Cuda 383 Best of 8.363@83.78 in the 1/8mile which is a mid 12 with a 1.89 60ft
Formula S recreation not original but making like they should have at the factory) Working on adding EFI
69 'Cuda Race Parts Car
76 Duster 273 recent transplant
95 Neon 2.0 SOHC best of 16.96
84 Dodge Ram D50 transplanting 360

[70gtx]

im going to the bank in the morning if all goes good i'm a gonna go for the whole bowl of wax. new ross flat top's (with reliefs).030 over,eagle rods, indy s/r heads with a little bowl clean up,i have a cam 312/316 .540 .560 lunati solid, new 3000 ?stall and the six pack.
what make and size stall should i have? got 391 gears runs about 3400 at 60 .not sure on the size because motor should put out some good horse and torque.

[70gtx]

oh something else piston should come to about .017 to the deck andheads are 75-79cc should get me to 10.5to 1 or so, the way i figure.any reply or thoughts on this combo before fri. night would be great.what do you think crank rod & piston balance should run?

[Dragracerr]

You may want to re-calculate that CR. Based on the data you provided and excluding the impact if/any valve relief’s will have, I calculated ~9.6 to 1 Cr. This is also assuming you are not going to cut the heads, and will be using a 446 (.03) with FEL-PRO 1009 head gaskets.
Would however make a nice cruiser combo with the occasional No2 squirt. Any idea what the cam center is? If you already have the 3G converter give it a try, although hold out on some of mom's bankroll, I have a hunch you may need a little more stall

[70gtx]

I USED PRESTAGE.COM CALCUL;ATOR 4.350,3.75 DECK .017, GASKET.040,HEAD 79CC,PISTON RELIEF 3CC. IT COME UP TO 10.52: 1

[Sport]

GTX.Dont run to the bank to soon, You are doing a lot of good research for your build up. Keep it up, dont let the Mopar Fever get to you ,or you could end up with parts on your living room floor that you dont want 2 weeks later like I did .If your positive about what you want then go for it ( Quote its cheaper to go fast the first time)has a lot of truth to it .But you can still over do it . I read all the posts I can so I can pick up info for my next build, up A low deck 71 block 400 stroker that Ihave been sitting on for 10 years. This post of yours caught my attention because of the S/R vs 915 I want to see the S/R vs B1/BS comparison. Iheard the B1/BS flows the same or more out box 290 cfm intake but has smaller combustion chamber 65.cc. vs theIndy S.R.@75 cc.Does anybody have more info on this.Sport

[Sport]

GTX.Dont run to the bank to soon, You are doing a lot of good research for your build up. Keep it up, dont let the Mopar Fever get to you ,or you could end up with parts on your living room floor that you dont want 2 weeks later like I did .If your positive about what you want then go for it ( Quote its cheaper to go fast the first time)has a lot of truth to it .But you can still over do it . I read all the posts I can so I can pick up info for my next build, up A low deck 71 block 400 stroker that Ihave been sitting on for 10 years. This post of yours caught my attention because of the S/R vs 915 I want to see the S/R vs B1/BS comparison. Iheard the B1/BS flows the same or more out box 290 cfm intake but has smaller combustion chamber 65.cc. vs theIndy S.R.@75 cc.Does anybody have more info on this.Sport

[DartGT66]

440Jim, the SR installation kit price may sound high and the price pf the oil hoses may be true, but the Indys use manley head bolts or studs. They are different length than the stockers and come with a 9/16" hex. Also the pushrods are longer than stock because of the 1/2" longer valves. Actually they are BB chevy +.100" 11/32" stem valves, so you might get a better deal buing them empty and get everything from cheapo sources, but I kind of doubpt that too. I have heard that the B1/BSand the SR's are about equal performance wise, when max ported the Indys should have a little more potential. For some reason almost all big name mopar builders use the Indys, B1/BS are relatively rarely used. I'm so simple that it makes me think the SR's might be better.

[70gtx]

i was thinking somemore if i end up .017 deck ,do they have a head gaset .030 so i can get quench at .047 or do i need to deck the blok ..010 is there other benefites to decking the block .if im going this far whats a $200.

[70gtx]

ya SPORT,i went with the s/r today compu flow is going to do some bowl work andgasket match intake.suposed to make heads flow with the cam i have. and all the rest of the parts i talked about earlier.going to deck the block to .005 to pistons & balance crank. HOPE THE REST HOLDS UP. HOPE IT'S CHEAPER GOING TO FAST ALL THE TIME

[Sport]

GTX Great choice on the heads ,someday I will have a set myself,or the B1Bs.The Ross pistons are top guality Ihear also, But you said they were going to be .030 over.And you said your block was .030 over with the TRWs I take it you dont plan on reboring this block? I reringed a stock block,piston engine that I have and everybody jumped me for not boring it. But it turned out fine and it runs great! But if you are going to put $550. Ross pistons in I would highly recomend a rebore. And if your not make sure you remove any ridge from the top of the cylinder bore left by the TRW,s As the new ring lands of the Ross,s will be different than that of the TRW,s. And if there is any ridge it will surely turn out to a ring breaker for the new Engine.I left out honing but thats giving.If Im telling you something you already know ,my apologys but you had typed .030 Ross,s Sport
.

[70gtx]

no i dont plan to rebore . just minimum honing. only has 1000 miles on the trw's new rods and bearings look like brane new. crank is .010/010 shiney as can be .but will use all new bearings with eagle rods. makes me wonder if i should even doing this but that one time at drag strip brought the kid back out .i will have the machinist check to make sure i got the right clearence for new rosses( i think .0055)
anyone want to buy trw and rods.

[440 Jim]

Originally posted by DartGT66:
440Jim, the SR installation kit price may sound high and the price of the oil hoses may be true, but the Indys use manley head bolts or studs.

I am making that decision now. From what I know, the $250 kit contains push rods, head bolts w/washers, and the oil line kit. Separately these cost:
$100 custom pushrods or cut to fit (Crane/MP)
$055 Manley head bolts for the Indy heads
$050 Indy oil line kit.
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$205 Total. Am I missing something? Even the valley pan spacers are only $12.00

[440 Jim]

Originally posted by Sport:
I heard the B1/BS flows the same or more out box 290 cfm intake but has smaller combustion chamber 65.cc. vs theIndy S.R.@75 cc.Does anybody have more info on this.Sport

Sport,
If you want 65cc, just mill the Indy 0.060 and you will have 65cc. That will cost you around $100, but the B1/BS valve gear can cost alot more than the "stock" geometry that fits the SR.

[70gtx]

installation kit ,ill let you know soon but ithink it is just the 3 items.then i got told i would have oil leak problems un less you buy the custom valley cover.

[Sport]

440Jim thanks ,I had thought that with the B1Bs heads that everything would interchange.Through you and other posts I have learned that you need offset rockers.I already have a new set of crane 1.6,s Scatcth the B1Bs,s Indy Sr,s it is and yes I do need the 65cc. combustion chambers to keep my thermal comp. ratio up switching from iron to aluminum ,thanks for the math .Sport

[WEDGEMAN3]

GTX....,Im going to quote SPORT "Dont run to the bank too soon!".I cant believe all the great information I have gotten just by reading the posts on this site ! I am planning a 440 for a 68'Dart I just got my hands on and im like a " Kid in a Candy Store" Anything you want to know about and all you have to do is ask.Doing it right the first time sure makes alot of sense to me !

------------------
WEDGEMAN3

[DartGT66]

OK 440Jim I stand corrected about the good price of the assembly kit. However, don't use the MP cut to length pushrods, they are thin wall soft tubing with loose ends if they haven't changed their supplier lately.

[Dragracerr]

'70 GTX, I apologize, you are absolutely correct, somewhere along the process of punching the calculator buttons I apparently hit the wrong key. Being a "old school" guy I have always calculated the CR by hand. You obviously don’t need this formula, but here it is if you want to bounce numbers around without the conveniance of today’s software programs.

Comb. chamber CC's + Gasket CC's + deck CC's + (CI x 2.0483*) *different standard for different # of cyl's this on is for 8
_____________________________________________

Comb. chamber CC's + Gasket CC's + Deck CC's

I have been watching the posts regarding these head comparisons, the last couple have pegged the influences dead middle. Don’t compare the B1S1 to the Indy SR's, the B1S1 is more parallel to the Indy -1's.
The SR's were designed by Indy to fill the gap between OEM and Race heads for the dual purpose application, and would be more appropriate for most of the applications described on this and several other threads listed here and the Dragracing forum.

-- JK

[440 Jim]

Originally posted by DartGT66:
OK 440Jim I stand corrected about the good price of the assembly kit. However, don't use the MP cut to length pushrods, they are thin wall soft tubing with loose ends if they haven't changed their supplier lately.

The kit price is not bad, just doesn't save any money and you get the pushrod length they send. I had Crane make me the custom length pushrods in my 440, $117 with shipping. They are 3/8, but not heat treated (a few more $$$). Do you know any good cut to length kits? Maybe I will just have Crane make them for my 451. I think the heat treatment (hardened) will add some strength.

[440 Jim]

Originally posted by 70gtx:
installation kit ,ill let you know soon but ithink it is just the 3 items.

Let us know what Manley part number you get too.