gbarmore

Here are my goals...

1) 'Hot' Street car, occasional autocross, ~2,500 miles / year
2) Looking for very stout low to mid-rpm range torque
3) All out HP is not the goal, but would like to be in the 450+ range
4) A bit lopey is preferred

Current set-up
383 - 4.030 Bore- 3.75 Stroke
Cast Scat crank, H-Beam rods, Probe forged pistons (~6,200 RPM limit)
Edelbrock Performer RPM Dual Plane Intake (7104)
FiTech EFI / Aeromotive 340lph Phantom Stealth
10.8:1 Compression
3:55 rear
2004-R Auto trans
~2800 Converter (will upgrade as necessary)
1 7/8" Headers into Sidepipes
Howard's Hyd. Roller
VALVE LIFT WITH 1.5 ROCKERS : INT .530 / EXT .545
DURATION @0.050" : INT .233 / EXT .241
ADVERTISED - INT .286 / EXT .294
LOBE SEPARATION ANGLE : 110º

Have always felt the motor was a bit 'lazy', but it could have been the combination of the mediocre ProComp 210cc heads, 1.6 rockers, and fairly long duration. I will be changing out these heads with AFR195 'competition' heads that flow like this.. (maybe my existing Cam is fine and I just needed better heads to match?)

195cc Competition Head Flow Chart

Lift -.200 .300 .400 .500 .550 .600
Int - 151 211 260 293 304 308
Exh- 125 172 207 224 229 233

Looking forward to recommendations from those of you that have put together a few combos. Thanks in advance!

fishslayer143

single plane intake?

cv67

Heads will be a nice improvment

what carb? Getting that fine tuned (with an 02 sensor a plus), right curve on the distributor will make a NIGHT and day difference.

If it were me Id use more gear and converter.

One change at a time so you know what does what.

gbarmore

Sorry, forgot that little detail! Edelbrock Performer RPM Dual Plane

Running a FiTech GoEFI 600. So more gear and converter and leave the existing Cam alone?? I thought the same thing, one change at a time. I'd love to do that but really didn't want to do heads, then pull the motor again to do a cam.

I update my original post to include the intake and EFI info..... Duh, on my part....

Thanks guys.

AirBusPilot

IMO, your headers are too small for 450hp.

fishslayer143

how much ignition timing and when is it all in?...that cam needs lots of timing ...from what you list, I think your heads are too big and your gears are too small... The cam in my 383 Stroker is bigger than yours , I m putting out 525HP @6300 rpm and 498 Ft Lbs and its strong even at 1500 rpm, all the way to 6800 .. nothing lazy about it.....I do have 3.73 gears and ported /polished Alum 195 heads , RPM Air Gap and Quickfuel feeding it

gbarmore

Good catch, I just verified out in the garage, they are 1 7/8" Headers.

gbarmore

I was doing some experimenting with different timing, but it seemed to run well with 18 initial and 34 degrees all in at about 2600rpm. Builder recommended not going much higher due to the higher compression, but I never had any issues with pinging that I recall. Admittedly, I never really felt like I got it timed right. I kept vac advance disconnected with the FiTech because it caused the motor to idle way too high. When I had my Q-Jet, it was connected and worked fine.

That's a pretty stout 383 you have there. What cam / compression?

Les

I think the heads will help a lot. That and verifying that your ignition curve is optimized should really pick things up. If you're still not happy you could always throw more rear gear at it to hit the sweet spot if the cam still feels a bit soft. However, I don't think the cam is the problem or that you'll feel the need for more gear. When you get it sorted out to your satisfaction I'd love to hear it rip through a couple gears.

NewbVetteGuy

What?!? No. Just no.

If he wants to focus on torque through mid range with 450hp in a 383, I'd say they're a bit too large. I'd still go with 1 5/8th headers, but I doubt he's going to buy new headers at this point.


Adam

NewbVetteGuy

Chris Straub just posted an incredible dyno result from a 383 on here just a couple of days ago;worth looking at his cam selection...

https://www.corvetteforum.com/forums...results-2.html Check out Chris Straub's 383 Dyno sheet. If you're going to spend all that $$$$ on those heads and the rest of that engine, just call a pro like Chris and get him to make a cam to match your combo and goals.

That 383 stroker made 533HP with 1 5/8" headers and AFR 195 heads, by-the-way. So 1 7/8" headers... -Why?

Adam

AirBusPilot

1 5/8 would choke an engine otherwise designed for 450hp.

That size would be good for a mild build only.

cv67

Can he even get say a 1-3/4 primary with sidepipes?
If his pipes only come in 1-7/8 leave it
Agree with dist curve. Couldnt get mine right for the life of me finally took it to someone wiht a Sun machine who took the msd bushings in the trash put his own in etc. Wow....felt like i had a completlety different motor. Came on hard and man did it pull like a banshee!
Had I kept fooling with curve kits would never have gotten it right.

rklessdriver

This is the last 383 I did for a CF member and its very similar to what you want to build.

535HP and 487TQ.

All the info is in the thread below. Like I said very similar combo to what you want to build. Very simple but powerful engine.

https://www.corvetteforum.com/forums...95-dyno-s.html

The camshaft came from Mike Jones. It's a grind I use on street type engines that need good driveability and a good smooth power delivery. This same cam has made almost 600HP and run 126MPH in the 1/4 mile with more compression, more rocker ratio and bigger cyl heads in another CF members 93 convertible with a 383inch LT4 based engine that I built.

http://jonescams.com/

Will

NewbVetteGuy

I think Chris Schraub forgot to tell his dyno that; maybe if he informs the dyno and puts the engine on it again he'll get different results and that 533hp will drop down to a "more appropriate" 410 or so.


In all seriousness, I think the OP edited his original post between when you saw it and when I saw it. My guess is that it said 1 5/8" when you saw it and you were commenting that the general guideline is to go bigger at this power level; -when I viewed the post it already said 1 7/8" so I took your comment to say go bigger than 1 7/8" for a targeted 450hp build -which was already one size too big, IMHO.


Adam

cv67

1-5/8 is fine for most street builds;in upper ranges may see a slight something with a larger primary but if thats what you got just use it. Or not

AirBusPilot

Gotcha.

I have to believe that 1 5/8 is a misprint on the dyno sheet, though.

Kacyc3

we have similar goals and now you got me thinking my cam is to small.

gbarmore

I'll be sure to share some the sweet exhaust notes with you when it get back on the road in the spring

Thanks for the link, I will check it out.

I definitely never really got my ignition curve optimized, no doubt there. Did you dyno it or just "SOTP" tuning??

Thanks Will, I'll check this out.

I'll be sticking with my 1 3/4" headers, not reinvesting there. Anyone ever see the episode of (I think) Engine Power where they bashed in the headers on all 8 cylinders and it had almost ZERO affect on power or torque? Truly amazing, and it makes the discussion around Primary size seem irrelevant vs. getting the timing, converter, cam etc correct.

cooper9811

Do a little research on cam/head combinations. AFRs tend to like little to no duration split. I believe you may be giving up some power with a split that large.

PM sent on that subject