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383 build

5K views 33 replies 5 participants last post by  eutu1960 
#1 ·
I am putting together a budget mild 383 build using my stock TPI intake, I am not interested in high rpm or all out power. here is a list of what I have right now.

bare 383 reman roller block.

eagle 383 rotating assembly with 12cc dished pistons.

Comp Cam 264H-R12 (recommended by comp)
Valve Lift .480 int/ex
108 intake centerline
duration .050 int 210 ex 220
duration .006 int 264 ex 274

and all the supporting parts.

For heads I was going to have my 113 D-Port heads with 58cc chambers rebuilt and port mach the intake. I already have headers. This will be placed in my vette with 700r trans and 2.59 gears.

I am worried that I may be going to high in my compression and may go with bigger chambers. Any Thoughts appreciated.
 
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#2 ·
I am putting together a budget mild 383 build using my stock TPI intake, I am not interested in high rpm or all out power,,,

good luck with the project. 58 cc chambers will likely cause cr issues. what pistons have you looked at and are you married to those heads?if so,why?
the TPI is also going to limit power.
will have good low rpm power though.
 
#4 ·
the eagle kit came with speed pro 12cc dish Hypereutectic pistons, I am not married to the heads but those are the ones that came off my stock L98 with 189k on the motor and have seen some good builds using those heads and I was planing on having them rebuilt for budget reasons. I also am staying with the stock TPI so I do not see the point in going to bigger ports on the heads. I've been playing with this compression calculator. Compression Ratio Calculator | Tools | Diamond Racing Pistons and have come up with a compresion ratio of 10.69. that would be running about .045 piston to head.
 
#9 · (Edited)
Are you using the stock ECM? If yes (hopefully not) then you'll need someone to flash it, and what year is your TPI setup (MAF or MAP)? Something to consider if you swap out to a set of aftermarket heads is the intake port size. The TPI lower intake ports won't cover some aftermarket heads which will require some welding and machining. It appears that you're building a low rpm torque monster, and with that in mind, I think it would be more economical to swap pistons, rather than the heads. Even a set of stock Vortecs at 62cc are going to have you a bit high on your compression. Are you planning a home port job on your TPI (I think you should)?

Keep something in mind with your build, stock TPI with a 383 is going to be a 1500-4500 rpm engine. I can imagine that it will feel like you're dragging a boat anchor behind you at 5500 though. If you're happy with a sub 5000 rpm limit, then this will work great. If you want more rpm's then, you'll need some heavy mods to you're TPI or an HSR. But the HSR brings more expenses. Personally, I like this build for a street cruiser when there is no concern high rpm performance. Your motor will make toque below 3500 rpm's that most conventional builds aren't seeing til 4500+; which will make this extrmely streetable and somewhat fuel economical. I think that most will advise that 383 and 'fuel economy' are not synomous terms.

Give us some answers and good luck.



For older smog heads, 8:1. For a modern iron head like Vortecs, 8.5:1. Aluminum heads, 9:1.
Joker, is 9:1 for aluminum heads OK even with the stock aluminum heads? I would think that there would not be much benefit between having the DCR much over 8:5 with cam he is planning to run.
 
#10 · (Edited)
Forgot to mention that what you're doing has been done thousands of times with alot of success (do a search at ThirdGen.org), don't let someone talk you out of it if you can live with the operating limits of the TPI. Stock GM TPI is the best looking underhood eye candy that GM ever made in stock form, IMO. And the functionality of it is just an added benefit. The roller cam is going to be a big plus for your build. I don't know if the one you have is the 'answer', but it looks OK to me (I don't recommend cams.)

Good luck - Jim
 
#11 ·
The only time I seen 5000rpm with the stock motor is when I did some data logging, my tpi system uses map and the cam comp recommended is supposed to work well with the stock computer, torque converter and gearing that I have. using virtual dyno I should be making about 350 hp /400 tq. which is more than I need. I plan on doing some port matching and may go with these heads from Summit Summit Racing® Aluminum Cylinder Heads for Small Chevy SUM-162108 - Free Shipping on Orders Over $99 at Summit Racing I may go with AFR 180's with 65cc chambers, a member over on the corvette furom is a distributor for AFR and can get me a set for $1369 plus shipping. I was hopping to run a tighter budget. but I expected to spend more than I planned.
 
#13 ·
I've never used that cam in a 383, or, a TPI setup.I have used it 3 different Vortec headed 350 motors.2 of those were with the Vortec's EFI system with custom tuning.1 was a carb build &did go to the Dyno.It made 375 HP & 420 ft/lb.It is a fast ramp cam & with somewhat early IVC (intake valve closing) which retains cylinder psi.This can run DCR up.IIRC, the DCR on the 350's was in the 8.6:1 range with KB-193 D cup pistons (12cc), but we had no problems.SCR was 9.7:1.
 
#16 ·
That's salty.

Also forgot to mention that you're going to be pushing those stock 22 lb injectors to the limit before 350 HP. At 43.5 psi of fuel pressure you're going to be in need of 27's at a minimum. And that's another stock tune issue.
TPICHIPS | GM Fuel Injection for the average guy
Harris Performance has a decent reputation for being able to get a stock PCM working for a hopped up TPI setup. I've never used them, but did call them before we decided to go MegaSquirt. Nice people and they'll be able to tell you if what you doing is going to be tuneable.
 
#22 ·
64nailhead I am holding off on the tune until after I decide on the heads and the motor is back together. I will then give them a call, With the stock TPI I don't think I would be much more than just over 300hp at the crank, I already have 24lb injectors I tried them with my stock L98 and my blm's where bottomed out after I get her tuned and running I will do some data logging and adjust from there. Thanks for the link to tpichips.
 
#23 ·
I think your HP estimate is off. I was making that, over 300, with a 327 and a pair of bad heads from '69. Look at it this way, if you only make 300 crank hp with a 383, then something is well out of whack with either your build or tune. You would have to intentionally sabotage your car for it to perform that badly - so,,,,,let's not do that:thumbup:

Those 24's are good for only 300 hp. I wouldn't go smaller than a set of 36's and would strongly recommend 42's as they will be plenty no matter what you do. I made the mistake of buying 27's originally prior to adding boost and they were maxed at out with the 327 by 5300; which wasn't the end of the world as it was tailing off due to lack of air anyway.

Good luck - Jim
 
#24 ·
I thought I would update my thread, I decided to just stay with the stock heads I spent some time blending the bowls, cleaning up the ports and gasket matching the intake. I then had the heads rebuilt including new stainless vales for around $670.00. The motors up and running and sounds real good I just need to work out some problems with the 25 year old engine wiring harness and get a tune.
 
#27 ·
Skoggin Dickey did a Vortec headed 350 TPI using their TPI/Vortec conversion lower intake.

Vortec heads netted them 300hp

L98 206º/206º .403/.415 on a 115º cam to ZZ4 cam208º/221º 0.474"/0.510" on a 112º went up to 335hp

ZZ4 cam to LT4 hotcam (218º/228º 0.525"/0.525" on a 112ºLSA) went to 360hp

runners and t-body saw 380+hp

I did a Vortec/TPI 355 with LT4 Hotcam kit, 1-3/4" headers, SLP runners, SDPC/Vortec lower, 32lb/hr Accel injectors no cats, stock TC and stock 3.42 gears and 700r4 trans in a 1985 IROC Z with the LB9 TPI 305 rated at 215hp @ 4400 /275 lb/ft torque @ 3200rpm
that ran a 15.8 @ 88 mph in the 1/4, bone stock

the newer Vortec TPI 355 ran a 13.7@100mph in the 1/4 mile with the stock ECM calibration, just fooled with the fuel pressure a bit.
The owner was reluctant to to recalibrate the ECM chip so it is what it s.

peace
Hog
 
#28 ·
I thought I would update this thread my motor now has just under 2500 miles on it so I decided to do a compression check.

#1-160 #2-165
#3-170 #4-160
#5-160 #6-165
#7-165 #8-162.5

I did end up using the stock heads and intake, I cleaned up, blended the bowls and ports on the heads and gasket matched and cleaned up the ports on the TPI intake. I opened up the combustion chambers to 61cc also before having them rebuilt, the 12cc dish pistons actual cc'd at 14 cc. I still have an idle issue but am real happy with the way the motor runs otherwise, one day maybe I will have it dynoed. I was never able to find a vacuum leak so I had it checked with a smoke machine and he also checked the ignition and was not able to find a vacuum leak or a problem with the ignition. so I will have to keep looking at it to see what I can do. Knock counts are low and the spark plugs dont show any sign of detonation. I emailed compcams about my vacuum with the 08-302-8 cam and they said that it was ok.
 
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#33 ·
Thanks for the tips, my hole suspension has been rebuilt, including smart struts and the brackets that keep your camber at 0 degrees throughout the wheel travel. definitely needs more grip, lower gears would help but I use it mostly for long trips and car shows than the 1/4 mile, next year I may pick up some used rims and sticky tires, I might be better off spinning my tires though than blowing my little dana 36. here is a snap shot of the run in tuner pro from my last run were I had a lot of wheel spin off the line.
 

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