383 Combo newly bulit up

greenmile · Dec 2, 2010

Hello, i am deeply impressed with the level of in depth information in this forum, tried to get some hard facts information in other forums, but "Opinions" is mostly what i am getting.

Here is my questions:

1.) What HP/Torque output would you expect from the following Combo
2.) What changes would you suggest if i am aiming at acceptable street manner and 2000-5000RPM optimum range

-383 with Probe forged pistons (Flat Top), 1973 350 block 4mains
- Scat nodular 9000 series crank, Rods 5.7''
- AFR 195 Heads with 64cc's
- Projected static CR 10.6:1 (Will run in Germany, we have 98Octane, no problem for detonation issues)
- Roller Rocker arms 1.6 Ratio
- Edelbrock AVS Thunder 650cfm carburator
- Edelbrock RPM Air gap Manifold(Will be port matched to AFR head)
- Standard HEI Distributor
- Headman-Headers 1 5/8, original Car Mufflers(Corvette 1973 original)
- camshaft hyrd. flat tapped Mike Jones 110 LSA, duration @ 050 224/232, lift at valve 0.528â€œ / 0.534â€œ
-Manual transmission M20 with diff ratio 3.55

Would be very interested in your qualified thoughts,

Thanks

grumpyvette · Dec 2, 2010

greenmile · Dec 2, 2010

grumpyvette said:
this dyno should give you some idea, (417hp/434 tq) its usually reasonably close as a guide,but it shows flywheel not rear wheel hp/tq
you can expect the rear wheel hp/tq to be reduced about 19%

Thank you very much !!, does match pretty much what i have calculated myself.

HoweÂ´ver, would you be so kind to comment what i shall improve in your opinion if i make the following assumptions:

A.) Power Range 2000-5000RPM
B.) Main forcus is on increasing torque , M20 Muncie with 3.55 rear axle ratio present setup(Will not change that, may go for 5gear change later)

I want this combo to fire off from low RPM, will not drive it on race tracks......any suggestions for improvements(Even if they are small) ??

Thx

grumpyvette · Dec 2, 2010

my dyno program suggests that swapping to a moderate hydraulic roller cam like a crane 119661 would help the power curve

http://www.cranecams.com/product/cart.p ... il&p=24188

but that adds about $800 to the cost

yeah I know most people won,t read all the sub links that contain a great deal of info, but youll be very surprised at all the info those sub links contain

viewtopic.php?f=44&t=38&p=46#p46

viewtopic.php?f=50&t=428

viewtopic.php?f=50&t=1249

greenmile · Dec 2, 2010

Yes, i assumed that much, i did not want to spend that money, that is the reason for not going to hydraulic roller, i am aware of the potential power gain.Money rules.....i had to stop somewhere

)))
However, what you are showing me here is a bigger gain potential than i thought i would really see in reality......

My original exhaust pipes allready have 2.5'' don't want to go to 3'' also for noise reasons, will for now also stay with original mufflers and not change to Magnaflow, will first take a look at backpressure when combo is finished, if i see from my real dynocurves that i need to do something on the exhaust side, i still can go for the magnaflows.....correct strategy ???

PS: Original casted ex.manifolds will allready be exchanged with hedman headers, i thought 1 5/8 is ok for my combo.

I still am a bit worried about my 650cfm carburetor, according to the calculations (Vizard for example) i should be fine with what the engine needs, however i see a lot of 750holleys or even bigger combos all the time....do you think my 650 is a bottleneck ???

Cam selections is what you would recommend ???

grumpyvette · Dec 2, 2010

greenmile said:
Yes, i assumed that much, i did not want to spend that money, that is the reason for not going to hydraulic roller, i am aware of the potential power gain.Money rules.....i had to stop somewhere )))
However, what you are showing me here is a bigger gain potential than i thought i would really see in reality......

we almost ALL work on limited budgets

THE DYNO GAINS THE SOFTWARE SHOWS are based on the assumption that all other factors being close to ideal, they seldom are, so gains tend to be lower ,but the trends are obvious

My original exhaust pipes allready have 2.5'' don't want to go to 3'' also for noise reasons, will for now also stay with original mufflers and not change to Magnaflow, will first take a look at backpressure when combo is finished, if i see from my real dynocurves that i need to do something on the exhaust side, i still can go for the magnaflows.....correct strategy ???

for what your doing thats a good idea,test but Id doubt 2.5" pipes will be a significant restriction in the low and mid rpms (especially if theres an (X) pipe mounted as close as clearances under the car permit to the header collectors

PS: Original casted ex.manifolds will allready be exchanged with hedman headers, i thought 1 5/8 is ok for my combo.

its probable that the AVERAGE tq will be better with the 1 5/8" headers than with larger 1 3/4" headers but the PEAK power may be a bit restricted

I still am a bit worried about my 650cfm carburetor, according to the calculations (Vizard for example) i should be fine with what the engine needs, however i see a lot of 750holleys or even bigger combos all the time....do you think my 650 is a bottleneck ???

its VERY unlikely to be!, and its easy to test with a vacuum gauge

Cam selections is what you would recommend ???

given the application and goal and budget the cam is reasonably good, I doubt youll see any significant advantage to minor changes

these links and sub links may help

http://www.hotrod.com/articles/1206phr-383ci-small-block-chevy/

http://www.superchevy.com/how-to/76178-chevrolet-ht-383-engine/

http://www.enginelabs.com/news/dyno-video-qmp-builds-500-horse-383-stroker/

http://www.chevyhardcore.com/tech-stories/engine/building-the-little-383-small-block-that-could/

http://royalpurpleconsumer.com/wp-c...-block-in-six-easy-steps-hot-rod-magazine.pdf

viewtopic.php?f=55&t=1038

http://www.idavette.net/hib/camcon.htm

viewtopic.php?f=52&t=3802

viewtopic.php?f=55&t=2994&p=7857&hilit=+restrictive+carb#p7857

viewtopic.php?f=69&t=2378&p=6279&hilit=hemi#p6279

viewtopic.php?f=55&t=109&p=8207&hilit=+restrictive+carb#p8207

viewtopic.php?f=56&t=495&p=8333&hilit=+back+pressure#p8333

greenmile · Dec 2, 2010

Yes and Yes to all your statements.....

So in the end if i summarize you would see the most bang for the buck i can do IF i still want to improve with going to hydr. roller camshaft.......

I was wondering if a injection would be a nice thing to have, but again the money.....was looking into FASTor PowerjectionIII but was told the latter is no good.......

Anyways. thanks a lot for your input, if you are interested as soon as my engine is complete and dyno tested i will post the results if there is interest.

Regards,

grumpyvette · Dec 2, 2010

as soon as you get dyno results or just pictures of the engine assembly process and components or your car,please post them,
we are ALWAYS wanting to see the dyno results of any engine as it adds to our understanding of how things work in the real world vs theory

greenmile · Dec 2, 2010

OK, will do , will be after years end.

Thx again.

greenmile · Mar 21, 2011

Hello, i have promised to show results when engine is finished and car has been dynoed.
Now i have first results, will show graph in a few days.

However, i have reached 345 HP(measured after DIN spec) at 5.500 and max torque pretty much beetween 2.000-4.500 of about 500 NM.
Dynoed NOT on Engine Dyno but on rear wheel driven Dyno(Don't now the tech name in english for this kind of set up, sorry.)
Engine is now really a different animal compared to the status before the change
Hope i recall correctly from memory, will have the sheet soon and will upload.

Basically pretty identical built motors have reached 375HP, only difference is my carb (Edelbrock 650 AVS).
That identified the potential problem....below 3.800 it is running too rich, between 4.000-5.000 it is ok, above 5.000 it is going too lean.
All potential tested jet changes etc did not help solving the issue.
The 375 HP example was reached with a quickfuel 680 SS vacuum secondary carb, i am wondering if i should use this carb, or would you have other recommendations ?? (AES or other ??).
Will not use double pumper, not enough fuel economy there....

Any thoughts would be appreciated

grumpyvette · Mar 21, 2011

rear wheel hp generally runs about 17%-20% under flywheel hp, so your 345hp is close to the range predicted, of about 420 flywheel hp
your carb may need different metering rods and jets, a 650cfm carb thats properly tuned will support the additional flow and power, and you might want to play with carb spacers, and verify the exhaust back pressure, fuel pressure and ignition timing curve, youll generally want to get the fuel air ratio, on an engine running at below 3000rpm into the 13.7-14.7:1 ratio range, than slowly and evenly transition to a slightly richer 12.7-13.3 fuel air ratio range by the time you reach 6000rpm to maximize torque, and have less than 2 psi of exhaust back pressure
take the time to read thru these links and sub linked info

viewtopic.php?f=55&t=1820&p=10167&hilit=metering+rods#p10167

viewtopic.php?f=55&t=3052&p=10979&hilit=edelbrock+carb#p10979

http://garage.grumpysperformance.com/index.php?threads/a-383-build.10991/

viewtopic.php?f=55&t=109

viewtopic.php?f=55&t=4362&p=11450&hilit=carb+spacer#p11450

viewtopic.php?f=56&t=495

viewtopic.php?f=55&t=635

viewtopic.php?f=55&t=211

greenmile · Aug 2, 2013

For whatever reason, i never came around to post the dyno-graphs.
I apologize, here they are.
Maybe you can interpret anything further out of it.
The main things i still think to improve is carburetor change and magnaflow or flowmaster mufflers.
Regards,

grumpyvette · Aug 2, 2013

I wish I could see the intake manifold vacuum reading and fuel/air ratio at each 500rpm level, on that graph, plus the ignition advance curve used

" youll generally want to get the fuel air ratio, on an engine running at below 3000rpm into the 13.7-14.7:1 ratio range, than slowly and evenly transition to a slightly richer 12.7-13.3 fuel air ratio range by the time you reach 6000rpm to maximize torque, and have less than 2 psi of exhaust back pressure"

greenmile · Aug 5, 2013

Hy , thanks for your patience.....

All three items you are asking are not available and i forgot to ask these during the dyno(I was not present myself)
However, Car is right now again at repair shop, we currently discuss carburetor change.

I will ask for the items you are looking for if possible:

1.) Vacuum Intake
2.) Fuel ratio
3.) Iginition advance curve

Hope it will not take again 2years

))

grumpyvette · Aug 5, 2013

greenmile said:
Hy , thanks for your patience.....

All three items you are asking are not available and i forgot to ask these during the dyno(I was not present myself)
However, Car is right now again at repair shop, we currently discuss carburetor change.

I will ask for the items you are looking for if possible:

1.) Vacuum Intake IDEALLY LESS THAN 2PSI vacuum READING IN PLENUM AT WIDE OPEN THROTTLE AT PEAK RPM
2.) Fuel ratio 13.7:1-14.7:1 below 3000rpm, slowly and predictably shifting to 12.7:1-13:1 AT WIDE OPEN THROTTLE
3.) Iginition advance curve , VARIES WITH COMBO BUT 6-8 DEGREES ADVANCE AT IDLE AND 34-38 DEGREES AT 3200RPM IS WHERE I TRY TO START tuning

Hope it will not take again 2years ))

grumpyvette · Aug 27, 2013

PUMP GAS 383 build with v2.50BI heads. Built by Einstein Enginebuilder, and dyno'd on his Stuska.

4.030 x 3.750
HERES A RECENT COMBO THAT WAS POSTED ELSE WARE THAT PRODUCED DECENT RESULTS
certainly not a racing engine but one that would work well in some muscle cars
010 Block
Scat cast crank- Internal Balanced
Scat I beam Rods
236/240 110LC 106CL .600/.600 HYD Roller
10.9-1 93 Octane
1.6 Scorpion Rockers
98445 Howard Springs w/TI Retainers
5/16 .080 wall pushrods
Edelbrock 2892 w/1" epoxy in the plenum
1 3/4 3.50" collector headers
Kevco Oil Pan
QFT 850 carb.

Einstein Enginebuilder, "Those heads are awesome, not just fluff numbers they work, My combo just is not wild enough to see the full potential but this is something I think alot of people would like to build."

greenmile · Sep 5, 2013

Interesting thanks !!
I assume these numbers are not rear wheel but purely engine, therefore combo seems to be similar to mine(Remember, my numbers were rear wheel numbers!)

However my car is back from some repair and is up and running again.

Had problems wth Carb (Floats were totally destroyed, crumbled like somebody squeezed them with a lot of force) nobody can explain the root cause. I would have expected this failure only in turbo or compressor applications but mine does not have these .....

However, repaired the carb and additionally installed new magnaflow 2.5''mufflers (Threw the original away),

Can only say that engine is a different animal now, really much more responsive than before, now HP and NM from a driving feeling point of view seems to be closer to the dyno numbers i got.
Just wonder because the mufflers should not have such a big influence, think more that the damage i had in CARB allready influenced performance

Anyway, i know this is just guessing around and i should be happy with the results.

Further things on my list:
-Do all the proper measurements you have suggested to be able to look at the picture more in a scientific point of view in autumn
-Allready bought MSD ignition 6AL-2 programmable with getting rid of the restricition on mechanical timing curve (Springs & Vacuum), i will be completely free to program timing advance at any rpm level differently
-Will upgrade CARB to Quickfuell 650CFM which simply has more tuning capabilities than my current Edelbrock thunder AVS
-Onboard measurement of AFR with Sensor in Header installment with MTX wideband gauge. This should help me to look at AFR constantly
-Got gauge for vaccuum measurement in Plenum, will check soon.

These are the last things i will do till my lady goes to winter sleep for this year.
Will post results(Especially measurements)

greenmile · Dec 16, 2013

Just to let you know i am still here:

Parts finally arrived from US, i got:

-MSD ignition 6AL-2 programmable with getting rid of the restricition on mechanical timing curve (Springs & Vacuum)
-MSD Coil
-MSD Distributor high performance
-CARB Quickfuell 650CFM Blackdiamond (Including some main jets and air bleeder variants to fine tune)
-Onboard permanent measurement of AFR with Sensor in Header installment with MTX wideband gauge.
-gauge for vaccuum measurement in Plenu

Hopefully i will have time to install the goodies during winter, however will not be able to drive before march/April.

Will report back then,

Happy christmas

)

383 Combo newly bulit up

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