I am building a 383 stroker with a hydraulic roller 236 and 242 @50. The power band for the cam is 3000-6300 rpm. I will be running a TKO 600 with a 3:73 rear gear. The heads are AFR 210's with the Rev Kit. The crank is a Cola pushing 5.7 Eagle rods and Manley superlite pistons. My compression is calculating out to be 11.1 to 1. I currently have a Victor Jr. and Performer RPM port matched to Felpro 1206's. Any ideas for a first stab at the best intake for 1/4 mile. AFR tech guy says the Victor cross over point is going to be around 5000 rpm over the RPM. He is saying the RPM should pull the best times. I am thinking of shifting at 6400 and putting in a rev limit at 6500. Any ideas.

 

I would agree with the AFR tech.

With a hydraulic cam you will make more overall power with the dual plane. You would need some form of a solid cam to get more of the real upper end benefit out of a single plane.

But if you have both manifolds you will soon know which one works best for sure.

 

i have your exact combo except with 195 AFR heads...it runs like an animal...anyways, I've had both single plane vic jr. and an rpm air-gap. I felt more seat of the pants torque with the airgap, however; if you want bragging rights for numbers...go with the single plane. I'm sticking with the airgap because it just runs better...idles better, throttle response is better and so forth..but its nothing too obvious..just me.

 

Let the name tell you which one to buy.......single plane, for a single reason. In your case drag racing, and they usually work great. Dual plane, a dual reason, track and drivability on the street. I had a single plane on my LS5 when I bought it, and it didn't take long for that sucker to come off. I street drive mine, no racing yet.

Which one are you going to be using it for? Racing or street driving?

 

Is it RPM Air Gap ? I have run both, RPM Air Gap is a very good manifold it has the center divider cut down for upper RPM's.

I would still go with the Vic Jr with that combo. You won't lose anything down low ( contrary to 50 years of myths ) and you will gain a few ponies up top. I would wager the AFR tech in a 1/4 mile drag race Vic Jr would win especially if it's just a normal RPM dual plane

I have run the Vic Jr on my 355ci, 406ci and now my 427ci all driven on the street, I believe it is a great manifold, flow testing on my AFR 227 heads port matched to a Vic Jr manifold by AFR showed only a 3% loss in with the manifold bolted to the head

 

Morons talking

Take a small port to a big port. Speed goes down.

 

Who ever you talked to at AFR was a dumb azz.

Not even close


right from edelbrock on the air gap port size

Installation Notes: Use #8504 Edelbrock bolt kit. Recommended intake gasket: Edelbrock #7201. Manifold height: A-4.20", B-5.25" (same as #7101), see A/B Measurements. Port exit dimensions: 1.14" x 1.95".

right from the AFR 210 web site

Intake Port Gasket, 1.310" X 2.180" w/ 3/8" radius AFR #6820 or Fel-Pro #1206

Suggested Manifold Victor Jr or Super Victor, AFR #5005 & #5033

 

Cam is too small. RPM ranges in the catalogs are based on a 350. The extra displacement of the 383 will tame that cam and it will peak below 6000 rpm.

 

Steve, as head flow cfm goes up cam size can go down and make the same power.

I actually have a billet steel custom lobe 236/242 112 lsa cam in my 383 and it is about the biggest cam I would recommend for 383 ci. Mine is a solid roller version and it revs to 7500 nearly ever day I drive it. You have to use a good rev limiter

 

For what it's worth, I've run both on my 406, and currently am back to the RPM intake. My flat tappet solid cam will tip 7000 rpms even with the RPM intake, and low speed driving, especially idling in traffic is way better with the RPM. ( My fenders shake at idle)

Now for racing..........If you have a manual trans, or a 3000 or higher stall, I would venture to say........go Vic Jr. All the low end the RPM intake would have gained will be skipped, and by 3000 or so the Vic Jr will rip to the upper rpms.

 

George is right on the intake. Steve and George are both right on the cam. With your gearing and compression you could go up one size, which I would consider since my DCR was 8.28. I did a very similar 383 build with 10.4 to 1 compression AFR 195 competition ported heads. 236/242 cam and the rev kit plus a 150 nitrous shot. My cam is custom ground with a 114 LSA (for the nitrous) The Comp XE288HR peaks @ 6000 RPM installed straight up in a 383. (the rev kit will extend this somewhat and you won't get as much drop off when you do go over peak HP) It has 4 degrees advance ground in. Volumetric efficency is 100% from 4500 to 6500. as I installed it straight up with a 114 LSA. It will pull higher peak torque and HP numbers retarted 4 degrees but sacrifices power at the bottom end and midrange. Straight up fills the cylinder better at lower RPM (better for nitrous). Here are some Desktop Dyno projections.

10.4:1 compression
Straight up= 535hp @ 6000 rpm & 485 ft lbs @ 4500 rpm
Retarted 4 = 551hp @ 6500 rpm & 490 ft lbs @ 5000 rpm

As you can see the peak power and torque goes up 500 RPM with a 4 degree retard in cam timing. But it does this by increasing DCR which is dangerous when you are already at the limit.

 

I was incorrect on the cam data that I supplied above. The cam that I have is a Crower unit 112 deg lobe seperation, duration at 50 is 231 intake and 237 exhaust. Lobe lift is .348 intake and .355 exhaust. With 1.52 rockers, my lift is going up to 0.352 on the intake and .360 on the exhaust. Looking at the Crower web site, the closest cam that I see is a 236/244 @50 and its lift is around the same. They are calling top rpm 6200, peak HP 5700, peak torque 4200, low rpm 3000. Are your views the same, or should I go bigger.

 

I think the 231/237 cam is too small. Good probability you will have detonation issues with 11 to 1 compression. The 236/244 cam is a much better choice with your head, engine, gear combo. Is it also a 112 LSA? Those 210 AFR's are going to fill the cylinders well. Might have to dial total timing back a couple degrees to be able to run well on pump gas. I know this might shock some coming from me, but you might want to consider a street solid roller with your compression and intended use or drop compression a little if you want to go hydraulic roller.

 

Go bigger. I agree with an 11 to 1 motor that will run into probelms with smaller duration numbers. Those figures are for a 350, the 383 will tame the numbers down some. I agree with Gkull on the duration numbers, high 230s on the intake and lower 240s on the exhaust. I was going to run a 238/ 248 on a solid roller cam if I ever go the roller cam route.

I know this is going to be a weekend warrior so low speed driveability is not top priority with you, nor me. I ran the Vic Jr on my 350 and my 385 with no issues. You will spend very little time below 2500 rpm with your setup.

 

I think the 195 heads are a FAR BETTER choice for this motor. Because you oversized the intake ports, you should go with a RPM Air-Gap intake to regain some of the bottom end torque you lost with the wrong choice in cylinder heads. Peak HP and Torque figures have little effect on the how fast a car is, it is the BEST AVERAGE HP and Torque figures that win races. 3.75" stroker put a LOT of SIDE thrust on cylinder walls and high RPMs (over 7K) should not be part of the "picture" of a 383 build, since you working on the lower and mid range power the 195AFRs would have been a better choice. Leave the 210cc runners for the 400+ cu/in motors.

 

If 1/4 mile ETs are your sole priority, I'd definitely go with a one of the Victors, but for street/strip duty I'm on the fence. Not much help, I know, but the real reason I dropped in was to offer the following...

Where bottom end isn't an overriding concern I'm a fan of wider LSA's w/less advance myself (relative to commonplace 110*/+4* grinds), but feel it worth clarifying that DCR actually falls the less advanced or further retarded is cam timing. Also, unless I'm mistaken I believe 63mako is referring to having retarded a cam originally ground with 4* advance by 4* to actually end up with 0* cam advance / 114* ICA.

As mentioned, the better the heads, the less cam required to do the job, but you still have to watch the duration/CR relationship, or "DCR". Just be aware that the higher your peak VE% the higher true DCR will peak. Hope that's worth $.02 to someone.

FWIW, you've a fairly good group giving you feedback here.

TSW

 

I have a 383 with 6" rods, AFR 195 comp ported heads, just under 11:1 compression and I run a Victor JR and it makes around 580 hp with a solid roller on pump gas. If your main goal is to race it then there is no other choice but the Victor or a bowtie manifold. I also run a 2" carb spacer.

 

If I could turn back time, I probably would have bought the 195's. Since I am committed with the 210's, I would be more leaning toward changing the cam. This is a lot cheaper to hide from the wife. As for the compression, I have a variable timing module that plugs into my MSD system, so I can dial down my timing if I get stuck some where with out additive. I work for a refinery, so high octane additives are readily available. My big question for you guys is this; How much duration should I go to where my hydraulic lifters will float. Even with the REV kit, I was told that exceeding 6500-6600 rpm can be lunch time for a valve. I have changed plans for this car a few times and have accumulated a lot of spare racing parts. I would like to put a multi point fuel injection set up, which the fuel atomization would run my 11 to 1 on pump gas. I am waiting to see how Gordons engine works out with the mass flow. Thanks for all that suspension info George the other night. I will be dropping my trailing arms off with Gary to put Toms 31 spline outer axles in. If anybody has a cam in mind, I would surely appreciate your thoughts. 63 Mako, who made the cam that you mentioned (236-242)? What base circle was it ground on?

 

I have the FI up and running now. I still have a little work to do elsewhere on the car but as soon as it is up and running I'll stop by and we can "run" it.

 

Mine is a custom grind 114 LSA Comp Cams XE288HR. AFR rev kit. Standard base circle. Cleared my Callies Compstar 6" rods fine. A lot of the cam manufacturers Have Nitrous and Marine versions that are the same specs as their regular version but ground on a 112 or 113 LSA. Saves you the cost of a custom grind. With a hydraulic roller and rev kit invest in a rev limiter 6500 RPM is tops. Look at the Comp Cams XE294HR cam ground on a 112 LSA with Rev kit. Might fit your needs.
Just some info: The comp cams
(Extreme Energy) XE288HR 110 LSA operating range is 2500 to 6000 RPM
(Nitrous extreme) NX288HR 113 LSA operating range is 2400 to 6500 RPM
The only difference is the LSA. You will give up a few peak HP but picking up a wider torque band is a good trade off for me.
If FI is in your future, I really like the specs on the Comp cams 292 XFI HR13 for your build. It is a fuel injection retro roller. A little more duration, 113 LSA. Look at the operating range!! Look here on bottom of page 136:
http://compcams.com/technical/Catalo...67_226-227.pdf