Dean and Jeb, great info from you both. Just what I needed, thanks.

From your description, it looks like the 396 is what I want. Don't plan on adding juice or blower to this setup so the minor nits shouldn't apply. Have been reading about that Callies DragonSlayer crank. Sounds good, to me.

Could you explain what you mean by a "small base circle camshaft?" I don't plan to run anything wild... perhaps my current 222/230 but likely nothing bigger than a 230/244 (CC 306). Heads and intake are 'standard' CNC ported jobs with 2.02/1.57 valves, Comp Pro Magnum rollers, etc. OK for this app?

 

Hutch the base circle on the camshaft is dead opposite the peak lift (nose)... On engines with long strokes the connecting rods occasionally will make contact with the base circle of the camshaft because the additional stroke pulls them in farther. A reduced base circle camshaft is required to alleviate this contact. Some rods profiled for strokers will clear but just barely with no room for error; I like to be on the safe side!

Your heads will be fine for this application...I've built several 500+ hp 396's with ported LT4 castings and relatively mild camshafts. The one I'm building for a customer's Trans Am is using AFR 190 CNC heads, and a custom ground Crane hyd. roller cam with 232/238 duration @ .050" on a 114 lsa with .575"/.595" lift (1.6 ratio). This motor is 11.00:1 compression and is actually .060" over so it's a 401"... According to my Engine Analyzer Plus, which is rarely off more than 2%, this combination should make around 525 hp and 490 torque...
-Jeb

 

Hi jburnett,

You seem to know a lot about different types of heads and setups.
I have a L98 383 in my car, stock heads and cam.. engine is pretty much stock.
I'm wondering how much more HP or torque my engine is making? and what would be the best setup for my heads "porting, springs?" and what I should be looking into doing.

I want to keep my car streetable as much as possible, but I'd really like to get over the 300 hp possibly 400hp one day.

Thanks!

 

So basically you have a 383 bottom end with a stock L98 topside? Stock TPI? What are your cam specs? Compression? If you're still running the stock TPI that's your most significant bottleneck as the OEM unit was designed around a 305 engine and was severely flow limited on the stock 350" motors; much less a stroker which love air! Start with a larger base manifold and either a SuperRam or large tube runners. Your next area of restriction is the factory 113 heads which flow under 200 cfm on the intake stock... However, these heads can be ported to flow some respectable air when combined with larger 2.00"/1.56" valves (the largest reliably possible with the factory seats). However, for the price you would pay to have your 113's ported and GOOD larger valves installed you can pay for a set of aftermarket castings... For an application such as yours it's very difficult to beat AFR's 190cc heads; they have large enough ports to flow enough air to produce excellent hp but their cross-section is small enough to have good velocity and efficiency for torque production. However, if you want to stay with stock heads at the very least I would have the bowls blended the locating hump cut out of the combustion chambers to unshroud the spark and the larger valves installed with a good multi-angle valvejob...This will pick up airflow considerably while being less expensive that a full on port job. You can easily achieve 400 hp with the proper camshaft and tuning like this... As for what it makes right now, I have no idea because there are a lot of variables unanswered. If I were to venture a guess with a guesstimated 10.00:1 compression and completely stock topend breathing out of factory manifolds and a stock grind cam I would say you're probably making between 275 and 300 hp but probably an azzload of torque.

My wife's 383 is as good a combo as I can ask for in a "hot" daily drivable combination: It's an 11.00:1 383 with a heavily worked set of L98 113 heads, a custom ground Crane hyd. roller cam that is fairly mild for a stroker, an Accel SuperRam manifold and base, 58mm T.B., Hooker 1.75" headers and true dual 2.5" exhaust with no cats. This combination makes 470 hp and a little over 490 torque at the flywheel and propels her car (700R4 and 3.73 gears) to 11.70's at 118-119 on ET Streets...
-Jeb

 

For me those specs came up with ~525hp, and 560tq. (with open exhaust though)

 

On Engine Analyzer Plus (Version 2)? I did spec a set of 28" primaries at 1.75" and 10"x3" collectors but mine was open exhaust too...You can figure a little loss through a good dual 3" system but not much...
-Jeb

 

Hi jburnett.... thanks for the reply.

About the compression Ratio, I know that the heads were also shaved and I know this makes the compression ratio go higher. I was told to always put in high octane gas at the gas pump... NEVER lower, unless I really get suck somewhere that only has 87 or 89 Octane gas. I normally put in 91 to 94 Octane in the car.

When I had the engine rebuilt.... 3 or 4 years ago I didn't know much about engines and didn't ask a lot of questions before having it rebuilt and money was a bit of an issue back then, I didn't want to put lots and lots of money into the engine. I've been reading allot and been learning a lot in the past few months... this is why I have all these questions. One day I'll put some money in the engine but before then.. I want to learn and understand and see what options I have available.

When I had the engine rebuilt I was offered to have is stroked to a 383, I was like :confused: ??? then I was told it would increase the power for a little more money. I learned just a few days ago by reading a book that a 383 is actually using a crank from a 400 engine.... I was like COOL!

This is what I know about my engine, its a 383, the heads were shaved, the combustion chamber was bored 0.03 over and the engine was blue printed... to what extent was it blueprinted... I have no clue, but this is what I was told.
I know they needed to over bored it because there was some damage inside the combustion chamber.

I'm also wondering, since it was bored out... does this make my engine bigger then a 383 ? or is it the same ?


Anyway's, that's my story!

 

You had the CYLINDER BORES bored over...Not the combustion chamber (which is in the cylinder heads). A .030" overbore will make your motor a 4.030" bore and when combined with a 3.75" stroke you get 383 cid... Use this equation to get displacement: BORE X BORE X STROKE X .7854 X #OFCYLINDERS.

It would be nice to have a build sheet with this information...I always supply my customers with this because, God forbid, something happens to their engine and I'm not around; another builder can go by this data and know what's in the engine and what it's speced to... I suspect you have a fairly stock combination with the exception of the stroked short block; you have a lot of potential but a good deal of work to realize it.
-Jeb

 

Sorry about miss using the terminology's.. I'm still learning :rolleyes:

I didn't even know they gave built sheets... I think I might have the built sheet mixed up with all the part receipt I bought to rebuilt the car a few years ago.
Thanks for all the help!


[Modified by TheStef, 5:09 PM 8/19/2003]

 

Jeb,

Just wondering at what RPM the peak power and torque is going to be at on this combo?

Thanks in advance.

Robert

 

This motor should be done making power at around 6000...It's a street mill and this guy is a heavy autocrosser not road or drag racer. Though he does drive another vehicle daily he doesn't want to detract from the same capability with his T/A so he's decided to keep it on the mild side. He does have my old TPI plate system though so if additional muscle is needed he can squirt it.
-Jeb
PS- Sorry, you asked about the peaks... About 4000 for torque and 5800 for hp...


[Modified by jburnett, 3:56 PM 8/20/2003]