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Discussion Starter · #1 ·
Dear Hotrodders,


I am new to forum and would really appreciate your help with my stroker build. I have a local engine workshop putting together a SBC with forged internals, the block is a 4-bolt 2 rear main seal block that has been already machined to 0.040 over so the engine will be 385cid. My goal is to make the most power and remain streetable, a classic goal one might say. I have researched and looked into others projects but since all builds differ slightly I would appreciate if someone has a desktop dyno to check this combo and maybe someone here has already built a very similar engine.


Feel free to suggest better parts but keep in mind that no power adders allowed in here by law, and no NOS. Only N/A 385 with 98 oct fuel. which means basically max. around 11:1 CR. Stall will be around 2800-3000rpm, transmission is a Hughes TH-700r4 (600hp) and Rear gears will be most likely 3.90:1 (maybe 3.73:1). The car is a somewhat stripped Camaro -1971 if that matters, app. 3100lbs. This is not meant to be a strip only car for fastest possible 1/4mile but more of a weekend beast. Nevertheless, since this is going to be done I want to see max outcome of this build. Money is limited, therefore some items have been decided.


Main components that are already purchased:


- Block 0.040" over, and will be decked to 0


- Internals Scat forged crack and connecting rods


- Heads Trick Flow 23 Super 215cc with 67cc chamber “out of the box


- Intake Holley Strip Dominator single plane


- Headers full length 1 3/4" Summit





Items that I plan to install, you may suggest something else:


- Comp cams XR286R Mechanical Roller, 248/254 @ 0.576/0.582, LSA 110 degrees with 106 degrees centerline. Custom grind is also possible.


- Rockers 1.5 or 1.6?


- Carburetor around 800-850cfm, vacuum secondaries. Not a Double pumper! Which one, Holley, QFT or something else?


- MSD Distributor, which one?


- Forged Pistons. Maybe trickiest decision, since I aim to have around 11:1 CR and SCAT 4.9cc pistons would be 10.7:1 CR even when zero decked. Custom pistons may be an option if there is no other way of getting high enough CR...


The goal is to see maybe even 550+hp to as high as possible. Torque can’t be sacrificed completely since this is on the street but I assume that a 385 will make enough torque anyway to move that Camaro…




Do I get there with 11:1 or is higher CR needed? Can this be done with less CR?


What about the cam selection, more/less?


If someone could desktop dyno this combo and let me know what to expect. 385cid is not a huge engine but I believe a good 1.5hp/cid might be obtainable. What would it take parts wise? How to get most out of this build?

 

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your combo sounds around 500 hp or a little more? Need head flow numbers to pick the camshaft. I would use an 850 cfm carb of your choice(I like the double pumpers) The transmission/torque converter/rear gear ratio is a complimentary combination determined by primary use. 10.7:1 cr is great. Im guessing the 215 heads will be done around 580 hp so concentrate on that decision?

I say bigger cam/heads and carb and maybe bigger headers or step headers.
 

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Discussion Starter · #4 ·
Hello Vinniekq2,


thanks for your fast reply. First of all, my apologies, I did place this question to Engine-forum but don't know how the hell it ended up in Basics?!? If someone knows how to move it please advice and I will move it.


Back to the build. The head flow chart for TFS 215 is as follows:


Lift - INT - EXH
.100” - 66 – 58
.200” – 141 – 108
.300” – 199 – 147
.400” – 244 – 180
.500” – 273 – 202
.600” – 282 – 214
.700” – 287 - 223
They have made 622hp in a 406cid with 12:1 CR.
If I get 11:1 and 385 maybe we are looking at 520-540? Is this all its got?
Would you care to explain the suggestion more aggressive lift for cam? Maybe we starts facing idle problems or so...since more aggressive cams are 3000rpm++




.600” – 282 – 214


.700” – 287 - 223

 

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Discussion Starter · #5 ·
Hi hcompton,


thank you for your reply. Weight saving tips well noted. First I'll build the car up to par, engine up and running and then start shaving weight if needed.


Also copy/paste does not work well, duly noted :)


What do you think power wise? Any parts that are better changed to something else? Cam specs especially and CR? I think that the headers, carb etc "external" parts we can swap at the dyno but I need to nail the internals at this stage.
 

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Discussion Starter · #6 ·
Hi,


thanks for the input. This combo is what we came up with my engine builder, so therefore I assume that it is quite balanced and quite enough for street use and occasional strip. The whole car is under construction, all the Energy Suspension polybushings and mounts have been purchased and subframe connectors are next on the list. I think I need cowl hood since the engine will have single plane high-rise intake. 1.6 ratio rockers will be checked, if they are in the clear we will go with that. Here we have 98oct fuel so I think 107:1 is a safe bet. More CR will not likely bring much more HP anymore?
If you find any dynos, or threads with similar setups I would love to take a look.
 

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If Richard comes to this thread he might dyno sim your combo. Remember dyno sims are optimistic.
First thing I would do is bump the cam. standard .420 lobe on 108º square. I would use shaft rockers with a split. I would probably use 250º@.050 intake and 258º exhaust.
carb minimum 850 cfm but also consider a 950. Heads, I would use 227 dart/afr or equal profiler. These heads go in for light custom smoothing by a professional head porter(just a clean up).
headers would have primaries 30-36" long, collector length could be tuned on dyno tune day.The primaries could be as small as 1 3/4" stepped to 1 7/8" at the half way mark to the collectors.
This should peak around 6700 rpm,,,with usable power over the top
 

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Seems like a well thought out choice to me, I think it will easily make your 550HP goal.

I'd do a 1.6/1.5 split ratio on the rockers, the exhaust doesn't need the added lift and slight perceived duration bump, and 1.6 matched on the exhaust side typically just reduces torque without helping make any more upper rpm HP.

I'll agree a 950 carb would be best, QuickFuel is my pick over Holley as they typically have more added value features at a lower price point than Holley. Holley has been sitting on there butt for years, lagging behind Quickfuel and custom builders when it comes to value for the money spent.

Heads are pretty good for that 215cc port volume. Are there better? Yes, but nor better enough to just toss aside the Trickflows if you already have them. The Dart 227, Brodix 227, AFR 235 Eliminator, and Profiler are all a bit better, but we are talking just 20-30 HP on a potential 600 HP build. Since you already have the TF's, I'd just give them a smoothing over with 80 grit so everything is blended nice, that will pretty much get you 7-10cfm across the lift range and is dead easy to do

If you want that last little bit of missing compression ratio, have the heads flat milled .020"(.5mm), that will reduce the chamber just a hair over 3cc and bump you right to 11.1:1. Cheaper and easier than switching to a custom piston at this point.

Just for comparison, a friend over here did a similar combination of 377 cubic inch(4.155" x 3.48"), the Trickflow Super 195's with a hand blend, 257/267° [email protected]" .600/.600" lift, 108° LSA, 104° ICL Howards Mech Roller Cam, 10.7:1 compression, worked over Bowtie single plane intake, 850 carb, 1-3/4" headers.
It made 561 HP @ 6900 RPM on pump gas when dyno'd at Roush in Livonia, Michigan.

If you want to really get a better cam, check with either Chris Straub(he is "Straubtech" here at hotrodders) : Welcome to Straub Technologies. . .The Source of Custom Camshafts and Valvetrain
or
Mike jones at Jones Cams, fill out his cam recommendation sheet : Jones Cams
or
Terry Walters Performance and use their Cos-Cam service : Small Block Chevy


All in all, I think you've got a decent plan, a lot better than 90% of those who come on the board and ask.
 

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Discussion Starter · #9 ·
End result of the build

Hello guys and thanks to all for comments. Some time has passed and I decided to let you know how my engine build turned out. Many of the build threads start with high expectations but the actual build is not completed, or the results are not posted [probably due to disappointment :D ].
But I want to share my experience for the ones who want to know the end result.


So, I took the engine to a motor shop/builder who took it apart for inspection. It turns out that the seller had screwed me over! The engine was not a stroker at all! Fortunately the engine was actually overhauled and bored 0.040" over. The engine had not been used since, and it did have forged pistons. So basically I had to do a 357cid instead of 385...


We'll that was a bummer. Nevertheless on we go with the build. The cam was mild ~224 degrees, as well as the intake manifold was an Edelbrock RPM which is not the the best choice nowadays. My engine guy and I decided to stick with the Edelbrock RPM 60899 heads that I already had on the engine, and we deciced to go with Performer Air Gap intake. I also purchased a Lunati Voodoo 60104 cam to make the valves open more. Here is the list of parts:


SBC 350 0.040" over, stock crank
Forged Pistons 6.1cc (pistons ~0,025 down so head gasket is 0,015" for 0.04" quench)
CR 10.3
Performer RPM heads 60899
Performer Air Gap intake
Lunati Voodoo 60104 cam - 233/241 Hydr.flat tappet
Updated push rods and 1.5 rockers (Trickflow), old ones were some cheapos
Quick Fuel Slayer 600cc Vacuum Secondaries
MSD Hei distributor
1 5/8" Summit headers


The builder installed everything in the engine and it was transported to Engine dyno. He suspected that the combo would make no more than 350hp since the heads were those Edels, but I had played around with the desktop dyno 2000 and selected all the components based on using conservative estimates (I got estimate of 408hp/399 ft lbs from the DD2000).


With first pull carb-out-of-the-box we got roughly 380hp and 400ft lbs. Well there goes my builders estimate out of the window :D
We decided to add a 1" spacer with the carb and it was well worth it! We got instant gains of 25hp!
Some pulls during adjustments were up to 415hp but the lambda on the dyno revealed that the mixture was then running lean. So we went on to adjust the carb and switched the original jets (68/74) to 70/76. We got the a/f under control and improved on lower end also.


Final figures after all the adjustments were 403HP (@5300) and 573Nm (@4400) which is 422 ft lbs.


Of course since the original idea was to build a 500-550hp 383cid the results were not so impressive. And after the engine turned out to be just an overhauled stock engine I decided to use as much of the parts I had and see what we have. Ok, we might have made much more power with 383 stroker kit, but then again I would have to ditch my Edel heads for better ones, change to even more aggressive cam, buy bigger carb, buy the stroker kit, change rockers, pushrods etc etc. It is not cheap. So I am quite happy with the result since this was a budget build.


So when you think about the fact that I had to change only intake and cam (with pushrods/rockers) and I got to re-use my internals and Edelbrock heads, the figures are actually quite allright. Also to point out that the torque is above 500Nm all the way from 2700rpm-5700rpm! Avg.torque throughout the range is 542Nm or exactly 400 ft lbs! That is quite impressive for a standard size small block.


So, many of you guys probably have a dream or plan to build and engine. I'm sure that many times they probably do not get built due to various reasons, and in this case I ended up with something way different that I tought in the beginning.
But at the end of the day I do have 403HP/422Lbs 358cid, with the parts that I selected, and the combo is dyno proven so I must say that at least this build is completed.
As I fell far from the wanted power levels, I decided that I will use an OD tranny, either 700r4 or 200-4r and posi-lock with 3.73-3.90 gears to make the best out of the situation. The setup will go to a Camaro 1971 for street use, it is not a strip machine.


So, let me know what you think, hopefully this combo helps out someone who is building a 350!
 

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the extra cubes of a 1/4 inch stroker only adds maybe 40 hp potential. I think you build a nice mild street engine and should really enjoy the power too. Thanks for posting dyno results. Could you post the dyno sheet to show the final tune specs? complete with bsfc?
 

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Discussion Starter · #11 ·
Hi Vinnie,


sure, attached! Unfortunately the attachments are limited to 2mb so no video...
Bsfc, or fuel consumption I am not so familiar with, on the chart there is some figures, that is all info I have.


I think that reaching 400hp is pretty good with Edel heads with this torque curve. They sell the top end kit themselves with these heads and even wilder cam, but that combo is lacking torque compared to my results.
 

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bsfc figures show the efficiency of the engine and of course the a/f ratios show the tune you used. Both figures are good for future improvements if wanted.You make more torque than hp above 5200 rpm so there is power left on the table. As is, it will be a lot of fun with power all through the rpm range.
NOTE: the 1 inch spacer adding a lot of power says your engine wants to breathe deeper,,,
 

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Discussion Starter · #13 ·
Hi Vinnie,

I am too a little concerned about the fact that peak was reached before 5700rpm. The dyno expert said that the engine does not run higher rpms. Also his next concern were the valve springs, float not preferred :)

What do you mean exactly by "engine wants to breathe deeper"?
Any suggestions?

I think that the cam could be bigger but most likely its all in the heads since the cam specs are quite "high" for a 357:

Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,200-6,400
Intake Duration at 050 inch Lift: 233
Exhaust Duration at 050 inch Lift: 241
Duration at 050 inch Lift: 233 int./241 exh.
Advertised Intake Duration: 276
Advertised Exhaust Duration: 284
Advertised Duration: 276 int./284 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.504 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.525 in.
Valve Lift with Factory Rocker Arm Ratio: 0.504 int./0.525 exh.
Lobe Separation (degrees): 110

I did think that the engine would run up to 6000rpm. I see a couple of problems with my combo:

1. Heads - out of the box, might be limiting factor (can not do porting work to the heads within budget, it would cost the same as new heads)
2. Cam, maybe still too small, at least lift should be more (maybe even ~240/248 with ~0.570). And this is Hydr.FT, I know sucks *** but I do not want to spend on HR retrofit
3. If 1 and 2 were udated the carburator would be the next limiting factor, if not limiting the current combo already
4. Next thing I would assume would be 1 3/4" headers

So, with the parts I have and can not change (except for cam which is the cheapest) I think my combo will not push much more power out of it just by changing one element. If I would order new heads, lets say retail 1700$, when they reach my house the shipping, customs and tax would have brought the price up to 3000$. New cam is easy, around 300$ shipped but also then I would need new headers which are easily 700$ shipped and bigger carb another 600$. So in order to squeeze max out of 357cid I decided to use what I have. Now my builds total bill is around 3200$ on top of the parts that I had (price incl.work, changed parts and dyno)

Is there something I can easily do? Half a day at dyno costs around 800$ so I am not too keen on changing one part and doing that again either just for couple of horses...

And, as you all are thinking, my idea is to run the engine a little, get used to it, build a stronger one and then sell this one :D
 

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The carb spacer added plenum volume.
A dual plane intake uses a bigger carb than a single plane.
I would change out that cam anyways
use a solid cam with pressure oiled lifters
having the higher lift on the exhaust side with longer duration on the exhaust side is probably an issue
a bigger solid cam would likely idle better while making more power
750 cfm carb or 850 if you plan a radical build later

where do you live?
 

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Discussion Starter · #15 ·
I live in Finland. You can basically double any prices you find for parts in US...
So cam with less separation between intake/exhaust might be better?
And also a bit more carb.
 

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I think a cam swap and way bigger carb will net more than 30 hp. If you use a flat tappet hydraulic I don't see much power left in the engine.
With a solid I believe you can make 450 hp. How much camshaft can you live with? The bigger the cam the later the power comes on. Also the off idle power will start to soften but not much,,,,
 

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Hi Vinnie,

I am too a little concerned about the fact that peak was reached before 5700rpm. The dyno expert said that the engine does not run higher rpms. Also his next concern were the valve springs, float not preferred :)

What do you mean exactly by "engine wants to breathe deeper"?
Any suggestions?

I think that the cam could be bigger but most likely its all in the heads since the cam specs are quite "high" for a 357:

Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,200-6,400
Intake Duration at 050 inch Lift: 233
Exhaust Duration at 050 inch Lift: 241
Duration at 050 inch Lift: 233 int./241 exh.
Advertised Intake Duration: 276
Advertised Exhaust Duration: 284
Advertised Duration: 276 int./284 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.504 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.525 in.
Valve Lift with Factory Rocker Arm Ratio: 0.504 int./0.525 exh.
Lobe Separation (degrees): 110

I did think that the engine would run up to 6000rpm. I see a couple of problems with my combo:

1. Heads - out of the box, might be limiting factor (can not do porting work to the heads within budget, it would cost the same as new heads)
2. Cam, maybe still too small, at least lift should be more (maybe even ~240/248 with ~0.570). And this is Hydr.FT, I know sucks *** but I do not want to spend on HR retrofit
3. If 1 and 2 were udated the carburator would be the next limiting factor, if not limiting the current combo already
4. Next thing I would assume would be 1 3/4" headers

So, with the parts I have and can not change (except for cam which is the cheapest) I think my combo will not push much more power out of it just by changing one element. If I would order new heads, lets say retail 1700$, when they reach my house the shipping, customs and tax would have brought the price up to 3000$. New cam is easy, around 300$ shipped but also then I would need new headers which are easily 700$ shipped and bigger carb another 600$. So in order to squeeze max out of 357cid I decided to use what I have. Now my builds total bill is around 3200$ on top of the parts that I had (price incl.work, changed parts and dyno)

Is there something I can easily do? Half a day at dyno costs around 800$ so I am not too keen on changing one part and doing that again either just for couple of horses...

And, as you all are thinking, my idea is to run the engine a little, get used to it, build a stronger one and then sell this one :D

I think your missing what the dyno operator told to you. He's talking about the springs limiting RPM. What he means is they are losing control of the valves which is usually noted as valve float but what actually is happening is the spring lets the valve bounce off its seat when closing at high RPMs. This vents the compression and power pressures either into the intake or out the exhaust depending on which valves are bouncing thus preventing the engine from making any more power or RPM. So at whatever RPM where the valve float problem starts to affect power production that's the RPM and power the engine becomes limited to. This is easy to see on a dyno pull when it gets into this range as the power just curves over while the RPM rate of gain slows then finally stops its rate of climb.


Your parts selection is plenty good enough to support higher RPM's and power from a breathing standpoint. But the valve springs need replacing to something more stable at high RPMS. The usual place to start is with the springs the cam manufacturer kits with the cam. This would also apply to retainers and one cannot ignore valve weight either. Springs supplied with heads except for street and minor performance use are not suitable for large cams which you have and high RPM. The cam manufacturer knows more about the specific design spring the cam needs than any head manufacturer. Springs also have bad days they are very fussy about the manufacturing process and small errors in things like heat treat can result in springs that initially test well but fall down on strength after a few minutes of use. All springs do this to some point it's called taking a "set". The cam designer/manufacturer designates a spring that has need tested to insure its set strength will be sufficient to control the valve in the desired operating RPM range. This is a very complex subject that includes the weights of the spring, valve, locks, retainers, rocker, push rod, and tappet and how the spring reacts to this accumulation. Lubrication also gets involved as to how the tappet and rocker move with the oil some oils just can't meet the needed requirement. Saw a magazine article where they were testing rocker arms the oil they used was something of Roman Royalty and color but it couldn't keep the ball and socket fulcrum from burning at reasonable but high RPM with a very short time at that RPM . They blamed the ball and socket rocker design, but given that many engines ran big cams like they used at RPMs they went to but did so for long periods of time back in the "good old' days" without encountering this issue to any great extent, I'd say that this modern oil wasn't right for the application. They replaced the rockers with roller fulcrums to solve the problem that an oil brand/type change could have fixed. This simply points to the need to take everything into consideration before just changing parts.


Bogie
 

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Discussion Starter · #18 ·
Hi all,


OK, so valve springs most likely need an upgrade also. On the dyno the operator just did not even try to go past 5700. Maybe that is based on his experience, maybe I should have made him go a bit higher but since hp/tq curves were already falling I figured he knows best and besides what's the point of beaking something when there is no more power with current setup...By the way the engine was idling very smoothly around 800rpm and even this 60104 (that some consider almost not streetable) was pulling nice and steady. I still see that up to 6200-6500rpm is considered very streetable and there is power I can use every day.


Springs not able to keep up is a little surprising since I would think that Edelbrock would supply adequate springs to match the valves with their assembled 60899 heads as they have ran their own tests up to 6500rpm. Maybe the fact is that the Edel heads are on their flow limit without porting. I looks like anyway there is no one factor to adding power, all parts should be slightly different. If I change cam, I have to change valve springs and carb at least.


What I have done now is I contacted 5 cam specialists: Comp cams, Crower, Howards, Isky and of course Lunati.
I provided them with my dyno info, engine specs, car/trans/gear specs etc. Lets's see what they recommend. If they all say I have easy 30-40hp in sight, I might do it. If only small gains, no one would other than me would even notice that.
 

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Discussion Starter · #19 ·
Also, the dyno operator did not mention anything about valve float. I don't think we were even close to that.
 

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Who assembled the engine? Was the cam dialed in at exactly 0º?

How much thrashing are you willing to do on this engine?
Have you considered split ratio rockers?
 
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