Help me with some engine build decisions, please............

Now on the other hand I just put a SP1 and MT Scavengers on myold mans car and it made a world of difference, the butt dyno was impressed, but this was done a 13.85 comp iron head engine with a 499 lift 107 window rattler, so it was rather stifled with the stock intake and exhaust manifolds on it

 

Well, I'm staying with my ported iron exhausts and Performer intake. Now, on to the heads. If I buy a pair of the TA Aluminum SEs would it be smart to do the "little extra" porting before mounting them and, if so, should I buy them bare instead of fully built?

 

That's what I'm thinking too. I like stock appearing and low 12s are fine for this street cruiser. If I want to go any faster I can jump into my WE4 Turbo T and go mid 11s. (also a street car)

 

Oh yea no doubt, id go with assembled heads probably cheaper in the long run if you dont have any hardware to swap over, but a gasket match and bowl work will easily put you where your goal is and even moreso down the line, plus the better the head the less cam is needed further maximizing the sleeper effect

 

I'm not convinced that more cyl port flow will help with a performer. Up to you.

 

Any chance you could put up some video or audio of that 107 cam?

 

I been trying to get a decent video but thru my phone it sounds like static, but I will say between the cam, compression, headers and being a 4 speed it sounds absolutely amazing, I wish it had true duals and not the X pipe.but nonetheless its still nasty

 

I got my ta se heads from trishield. Jim had a special going big valves with extra porting and spring set for your cam. Call him and check.

 

I'd love to have Greg G. do my porting but, as you know, he isn't taking any head work presently. I'm gonna contact Tri-Shield. But, on a side note, with my mild build (Performer, QJ, ported iron exhaust, 230/245 TA cam) do you feel the extra porting on the TA SE heads is warranted?

 

you won't need that big of an overlap with the S1 SE's .. ported or stock

 

Your current build limitation is the exhaust manifolds. With what your talking about, an iron exhaust manifold motor (ported or not) is going to put out around 465-475 HP with the TA SE heads, with the upgrade work, flowing 315/220 at .500.

That same motor with headers, no other changes, puts out 515-520 HP.

Torque increase is even greater-- in the 50 ft lbs range typically.

I think Greg Gessler said many times that headers are worth .3 and 3mph on a wide variety of the typical street driven GS's.

I have built multiple different combos over the years, and played around a lot with camshafts, and those generalities are always the same.

There does not seem to be a magic "silver bullet" camshaft for iron exhaust manifolds.


AS far as extra porting, the bowl/chamber work is really fundamental when doing a set of alum heads. For the extra $350 they pick up a whole lot of flow. I can't imagine doing a set of those heads and leaving square corners on the short turns.

But I believe if you want to stick with the ex manifolds, a good set of $1500 or so ported small valve heads would work just fine.

If your going to go with alum heads, get the extra porting,and bolt up a set of shorty headers... they will go on outside the vehicle just like exhaust manifolds, and you can enjoy the extra power.. they are only about 8 numbers off a full length header.

JW

 

OK, I've made most of the decisions on the engine build except for the cam and compression which is the purpose of this post. Here's what I have so far:

Short Block - .040 over, Wysco forgings, stock crank, stock rods, GM NOS timing cover, Reman. balancer, stock flex plate
Heads - TA Stage 1 Aluminum purchased bare and additional porting done. Stage 1 swirl polished valves, TA springs, stock rockers and shafts, 3/8 adjustable pushrods.
Intake - Performer ported & gasket matched
Exhausts - Will chassis dyno with both ported stock exhausts and TA Shorty headers after the motor is installed.
Carb - Mark Northcutt performance build
Distributor - Dave Ray Small cap HEI with NAPA coil in stock location (20* mechanical & 10* vacuum with Crane adj unit)
Compression - 10.0 to 10.5 depending on cam selected.

I'm currently working to select a cam from several suggested by board members and Mike T. at TA. Before I make a decision I want to look at dynamic compression and quench data on each cam and here I have questions of you folks:

1) What is the recommended dynamic compression range for running 93 octane pump gas and what is the max dynamic compression I should consider to stay safe? I'm told that static CR can be as much as 10.5 with the aluminum heads and forged pistons but, what about dynamic?

2) What minimum quench distance is safe for this engine considering the growth of the forged pistons when hot? Can I go as low as .040 or .045? (the gasket will probably be about .040 installed)

3) I've become fairly familiar with the Pat Kelley calculators for figuring dynamic compression but, the advertised intake closing time ABDC changes depending on whether the cam is installed straight up or, advanced. The TA cam cards shows the intake centerline with 4* advance. Does that mean their cams are automatically +4* if installed straight up? So, which Intake closing figure should I use in the calculation, straight up or advanced?

 

Thanks Larry.

 

The Wallace DCR calculator uses the intake @ .050" duration figure to guesstimate the intake closing point. The calculator Larry suggested uses the advertised duration to figure the intake closing point. The advertised duration points are generally at .003" and represent the the actual intake closing point much better then a formula adding 15* to the @ .050" duration. To me, the better accuracy is worth the time and effort to download and install the calculator.

The max amount of pump gas dynamic compression tolerated depends on several factor other then the fuel, and will be in the range provided in the post above. Quench, chamber shape, chamber finish (hot spots) head material, intake charge temperature and engine temperature will all need to be optimized to use the maximum dynamic compression for 93 octane. Once optimized, a very hot day will mean removing ignition timing to eliminate detonation anyway. It would prudent to add a little room for error by being conservative here.

I would bet most of us do not go much closer then .035" on quench distance. Due to a machining error my 455 pistons were at +.005" once with a .036" compressed gasket. That was closer then I wanted to be, but it ran fine.

Cheryl

 

I'm getting over 11.0 SCR if I 0 deck the block with DCR over 8.2. Here are my calculations using the TA 413 cam.

bore - 4.3525
stroke - 3.9
combustion chamber - 63cc (TA says 62-64)
head gasket - .040
gasket bore - 4.365
deck clearance - 0
piston dish - 22cc (with notches, I believe)
413 cam - 286/296; Sep 113, ICL 109, intake closes 72*

So, where do my numbers differ from yours?

 

I have edited my OP as I mistakenly said I used the Wallace calculator. I'm actually using the Pat Kelley calculator which is the same one Larry is using.