DucatiDon

Ok...fair enough. I want to build a 383 sbc.
I will use AFR heads, most likely 215cc.
I want 450-500 crank hp.
I want the torque and hp peak to be relatively higher in the rpm band to reduce traction issues.
I have a low 1st gear RS500 and 3.73s, 215 tires.
I want it to appear as close to a stock 340hp engine as possible.
Go....

TCracingCA

215 heads good on a 383. The 3.73 with the 215 tires a problem. Thus I would try to get some deeper back space rims and mount some additional rubber even though 450-500 hp will still over power those tires. But I understand you are going for a sleeper look.
A 383 is traditionally not a high rpm engine (it can be, but not the way I have seen them built). It is known as a torque engine and capable of pulling from lower rpm points and can be built with fairly flat power curves. Thus using a cam to put your peak at a higher point negates the effectiveness and even the driveability.

Look at this (just listing examples and this doesn't necessarily apply to your build!

Cam 2800-6500
Intake 2500-6200
Heads 3200- 7000
Carb 2500- 6500
Etc.
Thus the math is your effective power band is:
3200-6200!

Thus if you had
Cam 2800-6500
Intake 2800-6500
Heads 2800-6500
Carb 2800-6500

It would run really good from 2800-6500! All of your parts are married and it would be a good running engine with the widest possible power band.

Also I don't see a problem targeting a compression ratio that can be made to run on the gas quality available, but the heads are the most important component and then marrying a camshaft would be the next goal.

427Hotrod

Here's a video of a 388" I did for my buddy a few years ago. Old style out of the box 215cc Dart's, 11.0 compression, 248* solid roller. Runs on pump gas with no issues...and he shifts it well over 7000 RPM every time he drives it. In this video it has a wide ratio Muncie and 3.36's.

A 383 has the same stroke as a 427..so it will rev pretty well. Heck....I actually never get that revving part. My 555" has a 4.250" stroke and it pulls past 7500 regularly and gets there in a nano-second. If the combo is right...it will rev.

Now that making it look like a 340Hp could change things a lot. Does that mean iron exhaust manifolds and tiny little intake and carb???




JIM

joebobbilly

Okay, here you go:

You're going to hear a lot of talk about quench and rod length, dwell time, etc, and for all that talk I say, **** on that waste of time.

A few things that you need to know is that heads flow better with dish pistons, as per the way the cylinder is 'drawn'. You should always stay away from domes if possible, use flat tops or dished.

Next, dwell time is a farce because the only dwell you need is for the flame to reach all the way cross the cylinder, nothing more. Extended dwell time means lower head flow because the piston acts like a cork sealing a hole.

Quench, here's a good one. Even if you zero deck the thing, you still have a head gasket hence quench area. If you stick the piston out of the hole and go to zero quench, at higher rpms there is some flex in the rod/piston assembly and that will make it go boom. Power is not there.

Real world experience (like you asked for):

About 17 years ago I did a 383 for a friend of mine. He wanted a budget pump gas capable motor for a 3200lb camaro.

383, not zero decked, 5.7 rods (powered metal), IRON vortec heads, 1.94/1.50 valves (170 runners), 244/254 @ .050 with .498 net lift 114 degree lobe separation flat tappet NOT roller, victor jr intake, about 10.2 to 1.

turbo 350 trans, 3.73 gears, 9 inch slick, stock chassis

shift 6200

best ET 10.47 quarter

32 degrees timing (at 20 degrees it slowed about a tenth and a half)

lots of confused faces and head scratching looking at centerbolt valve covers

joebobbilly

I wouldn't use the 215's.

427Hotrod

I'd like to hear more on that 10 sec Camaro. What sort of MPH did it turn? That's a solid 550-575HP requirement to run mid 10's@3200 lbs at somewhere around sea level.

Not too many 383/Vortec/.500"/114 LSA/flat tappet combos will do that with 3.73 gears and 6200 shift points.

Details/Pics/Timeslips?

That sounds like a well sorted combo...

JIM

joebobbilly

125ish IIRC. Many? More like any. Nobody uses iron heads so they turn their noses up at 'em. But iron heads make for consistency. It was a No electronics foot brake bracket car that was driven to the track sometimes. It was good enough to win the local track championship a couple times and the division 4 nhra championship once...gold card, wally and all.

lots of head scratching

claysmoker

http://www.wallaceracing.com/dynamic-cr.php

DucatiDon

Ok..looks like I'm at 8.5. Dynamic with a variety of cam choices.

TCracingCA

But that car had to be a lot lighter than 3200. The 350 trans had to be pretty built???? I mean pretty built! The 114 lobe would be a very broad rpm range, which I tend to favor but not quite to 114, I like 110-112 which works great on my long duration, and even thou they were 170 heads, I would guess some work to flow them was done. And also that car must have really hooked up to get 10 seconds.

I have a 355 combo that will run high 10 seconds. And guys tend to not want to believe a small block can 1/4 mile to that ET. Yes component stretch, is why you have tolerances. When I say Kiss, there is some tolerance there. I run Inconel Exhausts because I am not a fan of Titanium!!!!!!!! I run the Severe DutyPro Flow (Necked down) stainless valves intake by Manley on Crower Shaft Roller Lifters and such with some offset to widen the intake ports! And even though I am all aluminum on that engine. I do have another that is more stout in all iron with Ported Iron Phase 2's on a Bowtie iron block!

But because the guy said he was shooting for 500 hp, I went with the 215 heads, because they would be more capable to get to this number.

SupremeDeluxe

I realize this took another direction, but on the point of whether an "advertised" 11:1 factory engine will run on 93 pump gas without detonation, in my experience the answer is NO. With a stock timing curve and the vacuum advance hooked up, there will at least be some subtle, audible clatter under gradual part throttle acceleration between 2,000-3000 rpm where there is considerable vacuum advance. Not likely a concern for reliability or longevity, but the fact is it's there.

joebobbilly

The car was every bit of 3200, as it was an 85-6 model, uncut, all factory glass, crash bars in doors, the whole nine yards. It was put on the scales for the naysayers.

The turbo 350...I made a bracket to attach the torque arm...was bone stock for ....1200 passes(about half with the junkyard 350)...documented. I built it. At 1200 my friend decided he wanted a little safety factor, so we (I) put in a hardened sprag assembly, sun gear housing etc. the normal 350 garbage.

60' was 1.41-5 range. Hooked like glue, twisted like a pretzel left side about 2.5' in the air and passenger about a foot. Looked horrible but drove fine.

The heads were not hogged out but I did put my 2 cents in with the cartridge roll with emphasis where it needed. No flow bench.

The cam was not a roller.

Moser rear.

Foot braking is easy on parts.

I don't do tight lobe separations. They make noise, not power. 115, 117, no problem. Just depends on the situation.

It's easy to make power these days with all the aftermarket goodies available. But one thing that has never changed is that people always, for the most part, use too big a head, too much carb, wrong cam, over rev which gets you no where, and don't have a clue about valvetrain geometry or anything behind the flywheel.

The motor the 383 replaced was a junk yard 350 out of a van. I put some early 80's 305 heads on it, worked over, dual plane and hydraulic cam. 12 flat. I thought that was pretty good for around 800 bucks.

If the OP wants suggestions from a real world person, I'd suggest:

flat tops, 195cc afr 65cc chamber, compression ratio 10.2-10.4, crane part number 119681 hydraulic roller w/iron pressed distributor gear, single plane victor jr or edelbrock rpm air gap (not gonna make much difference), 750 carb, and don't spin past 63-6400 or you're wasting your time. No more than 34 degrees timing, set at 32.

Jetted right, that'll get all you ever wanted, plus you'd probably **** yourself.

But do whatever you want.

TCracingCA

More curious! I would not have thought that combination would get to 10's!

Sometimes someone hits on a magic combination that just gets it done! The torque arm on the tranny is the most interesting. I have seen oh so many 350 come apart. Maybe that locking in solid is something to be done. A lot of drag cars would solid mount the engine, and such. No I am an old street racer, so I would have come up on your combination and tried to evaluate it for a race and would have gotten surprised. I guess I don't know everything!

TCracingCA

I would get detonation like when running up a grade or laying into it. Thus that was when the general quality of the gas was not good. Then I built two engines and just decided to run Racing Gas at now $8 a gallon. Thus I actually haven't put this modern pump gas through my engine without heavy spiking. I am not sure but I think they took the tetra------ out of it out here and now have substituted in more ethanols and alcohol based mixes, but I have also heard that some of that kind of oxygenates the fuel and a 93 has the burn characteristics of some of the old higher octane blends.

I have this fuel quality vice Timing and horsepower article out of a vintage Circle Track circa around the late 80's where they directly tested like 15 different types of fuels in a basically stock engine to see which performed the best. The racing gases produced the highest numbers and supported the most advance, but actually not by much and then Chevron back in the day came out on top of the rest! The HP range by just changing fuel went from 165hp net to 201hp with only touching the advance and changing the fuel. Interesting article to read!

joebobbilly

Neither did anybody else, and I was doubtful. But first time down the track was 11:00's with 20 degrees timing (I was trying to slow it down since the driver had never been faster than 12's and wanted to test the torque arm solution). Real mild idle...kinda sounded like a 13 second car....until you hit the loud pedal. The iron heads and centerbolt valve covers just threw everybody for a loop. I got a kick out of it.

427Hotrod

Well...I wasn't there...so I'll take your word on it. I have no issue with iron heads...they can run VERY well....done it many times myself. BBC iron heads can do some incredible stuff. I used an old set of "Turbo" heads from GM that were killer in the late 70's compared to what else was available. The Vortec's blow them away with a smaller port. But as you mentioned with all the stuff available today in aluminum...it just makes sense to go that way if you can swing it.

I've seen quite a few Vortec headed and L98 headed C-4's run deep in the 11's with like 3.07 gears....heck even some TPI motors get there with a small hyd roller and never getting over 5500-5800 rpm. So there are definitely a couple of ways to get things done.

Got any links to pictures etc of the car?

JIM

DucatiDon

Back on topic....."IF" I decide to keep the 461 intake and rams horns, am I wasting money with AFR 210cc heads?

Im not completely opposed to headers and a performer RPM (or Z28/LT1 intake and Holley)...

But "IF" I was going the 461/rams horn route, would AFR 195cc be better? I definitely want aluminum to fight detonation.

Finally, In order to tie it all together, the cam I was considering is a Hyd Roller 240* @ .050 with .540 lift. Other than starving for air (aka rpm) what ill effects would choking it with the 461 and rams horns have?

Ill be happy with 385 at the wheels....but would like to squeeze out 400.... Is that realistic?

TCracingCA

Those are your biggest problem, because actually the intake doesn't give up much to a generic single plane. If you have the intake manifold worked somewhat (porting, and port matching with some flow aids like a carb spacer) then you are close and I think now the 195's with a slightly lower hp ambition would make you completely happy with the sleeper stock look you are going for. Under the car headers shouldn't ever be sneered at (by NCRS types and such maybe). Those are a signature that you like some performance. It will sound nastier also! I would call the cam tech guys and get a recommendation for your combo and balance the advice you receive! But it sounds like those numbers will work. The larger cubes will tame it down somewhat!

Subfixer

A couple of years ago I built a 400 using the 461 intake and ram's horns for my 64.
It dynoed at 460 hp with dyno headers. With the rams horns (hogged out as much as possible) it lost 80 hp with a best of 380 hp.

joebobbilly

You're not wasting money on the 210's, you're wasting power. You wanna make less power? Use the 210's. 210's are 7K rpm/600+ lift heads, neither of which you will have with a dual plane intake or hydraulic roller.

I'll also add that if that cam you have in mind has a similar exhaust duration and you are set on 11:1 with ramhorns, you have made a nice recipe for a detonating sob.

You want a 'sleeper', which calls for a cam that you won't find on a shelf.

The intake and exhaust manifolds are nothing more than extensions of the heads...bottlenecks at either end have consequences.

For what you want you need a cam with at least 12 degrees more exhaust than intake and a damn wide lobe separation.

Something along the lines of 238 intake 250 exhaust 115 lobe separation cut at 4 degrees advanced (111 centerline).

To alleviate the exhaust bottleneck you will have to 'clear the cylinders' as best possible with the longer duration exhaust and wider separation.

Either that or it'll run like a turd.

I think you can get there with ramhorns, but they will need to be matched to the exhaust ports of the heads. Same for the stock style intakes.