Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

383 sbc first dyno experience

General engine tech -- Drag Racing to Circle Track

Moderator: Team

steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

Arthur wrote: Sat May 14, 2022 2:55 am
steve cowan wrote: Fri May 13, 2022 5:56 pm To insight a bit of discussion I am curious on why peaks fell where they did and why it carries up top to 7000rpm.
The only headers I could use were my 1 3/4" 4 into 1 headers
Could not use the 13" extensions as they hit dyno frame.
So shelf header with 3" collector at 6" long with a curved extension to clear frame.
The 300-25 intake is to suit my Dart 180 shp heads so port match is far from perfect, testing carb spacers certainly changed my perspective on Google theory as well.
Nice work
Would you elaborate on your spacer journey -
Thanks Arthur,
The spacer deal was a eye opener for me that's for sure and I understand every combination responds differently.
We initially ran engine up with my 830 annual but I removed 130" needle and seats for new 110" just so we would not get caught out with fuel pressure confusion.
1" aluminium spacer with 4 hole timber spacer,ran engine in to seal up first 15 pulls on engine were with 28 degrees of timing and engine made over 500ft/lbs with 28 degrees, putting timing later pushed and smoothed power curves to 522 ft/lbs @5300rpm and 568 hp at 6600 .
We pulled with 830 carb but after adding jet up to in the 90 range and still lean we went to 850 carb .started at 88 jets all round no power valves.
We kept adding fuel and power increases, went from a 28 bleed down to 25 HSAB power increased.
So we are at 94 jet all round 25 HSAB still 28 degrees timing and around 515 ft/lbs 550hp
At this stage we have 1" open and 1" taped 4 hole spacer.
So now timing going in 30 degrees pushes power higher,32 power higher in rpm range.34 degrees torque down but hp up slightly at higher rpm.
36 degrees power down but AFR not going silly.
32 degrees to peak torque at 5300rpm and then 34deg up to 7000rpm nice power curve ,engine sounds very nice.
I check and set lash to spec 20" - 22" per cam card,replace oil filter every thing looks good, still on BR30 oil.
Fit 2 " open spacer that I made that fits perfectly and it's down 15 plus hp and AFR go goofy.
The boys say try a 2" 4 hole spacer no taper,I say it don't fit very nicely, they say try it.
Best torque and hp at highest rpm and AFR not moved on both sides throughout the range,I am in shock and thought they we having a go at me some how,I have known these guys for 35 years so anything is possible.
Put 1 " open under 4 hole and lost 10 hp.
Tighter lash was up on the curve.
Vac pump worth 5hp max at 11" and lost at 17" down 10hp
Expensive synthetic race oil 5w-30 was down 5hp on 19th pull and broke even on 20th pull.
Russell made sure that water and oil temps were stable as best as possible on all 20 pulls.
steve c
Arthur
Member
Member
Posts: 121
Joined: Sat Aug 13, 2005 6:21 pm
Location:
Contact:

Re: 383 sbc first dyno experience

Post by Arthur »

850 carb is downleg booster ?
Reducing plenum volume/ shape pointing to metering fluctuations into chamber
Exhaust collector extensions would of soothed it a little
End runner lash tests (ex) worth trying
Figuring the power delta between centre and end runners helps(manifold dependant)
Track testing your dyno settings will be interesting
Well documented tests
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

Arthur wrote: Sat May 14, 2022 4:20 am 850 carb is downleg booster ?
Reducing plenum volume/ shape pointing to metering fluctuations into chamber
Exhaust collector extensions would of soothed it a little
End runner lash tests (ex) worth trying
Figuring the power delta between centre and end runners helps(manifold dependant)
Track testing your dyno settings will be interesting
Well documented tests
Yes down leg booster,I changed the boosters they are smaller in overall size but 160" internal.
The bigger 1 3/4" tri-y is what I wanted to dyno with but would not fit so used the 4 into 1 headers without collector extensions as shop had curved collector with afr sensors to clear the dyno frame.
The chrome coated 1 5/8" tri-y with 21/2" collector I have used with those heads and I spent a lot of time welding and grinding those headers for port match.
I want to use them as a baseline.
Seems headers are a pain on dyno.if I can get 4 into 1 headers to fit in car I will track test with a total of 19" collector.
I have been told the bigger tri-y won't work with the factory merge in place but I will try them .have to weld in some AFR bungs first.
All the spark plugs look good but #7 a bit funky might be getting robbed by #5 cylinder.
Standard firing order cam.
Different exhaust lash test interesting for sure.
20220427_160117.jpg
20220505_092429.jpg
20220512_174551.jpg
20220512_174556.jpg
20220512_174837.jpg
20220512_174853.jpg
20220513_083121.jpg
20220513_083133.jpg
You do not have the required permissions to view the files attached to this post.
steve c
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

20220423_132438.jpg
20220423_132242.jpg
20220427_160047.jpg
20220427_160053.jpg
You do not have the required permissions to view the files attached to this post.
steve c
Elroy
Pro
Pro
Posts: 203
Joined: Tue Jul 16, 2019 12:46 pm
Location:

Re: 383 sbc first dyno experience

Post by Elroy »

As flat as it is at and around peak hp. It wouldnt surprise me if backing the cam up some would move peak hp up a couple hundred. Especially considering how conservative the valve timing is.

If that were the case, not saying it for sure is, that could put some power in it quick. A little gnarlier cam and you may have 600hp there.

Good Job Steve, very well thought out, meticulous. Nice to see. Mean power curve.
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

Elroy wrote: Sat May 14, 2022 6:19 am As flat as it is at and around peak hp. It wouldnt surprise me if backing the cam up some would move peak hp up a couple hundred. Especially considering how conservative the valve timing is.

If that were the case, not saying it for sure is, that could put some power in it quick. A little gnarlier cam and you may have 600hp there.

Good Job Steve, very well thought out, meticulous. Nice to see. Mean power curve.
Thanks for your input very appreciated, I have enough piston to valve up to 110 ICL
that puts PTV on exhaust at 90".
I have belt drive so easy to change.i run on unprepared track with radials so might knock some power out down low.
On the flip side though my car usually 60fts ok for power level .
Will be interesting
steve c
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

HQM383 wrote: Fri May 13, 2022 10:54 pm
steve cowan wrote: Fri May 13, 2022 10:20 pm
HQM383 wrote: Fri May 13, 2022 10:10 pm

So around .690” lift on the intake. 30* overlap @.050”. Int close 49* @.050” ABDC. That kind of intake area, overlap, intake velocity with port and valve sizes and enough exhaust timing for cylinder fill and closing intake early would go a long way to holding torque.

Installed at 109* ICL?
Jamie,
105 ICL,
I wanted to test ICL on dyno but boys said it will only rock the curve up or down and probably not show power increases??
Because my car heavy the suggestion was to test at the track
105* ICL, there it is in post 1. I should have checked.

Did you get a VE figure?
I played around with pipemax
522 tq but shows 600hp
At 6600rpm using 114 % VE
shows level 10 on tq but level 7 on hp if I am understanding it correctly.
Hope that makes sense.
Pipemax shows 256 @ 0.050 in and 264 @ 0.50"ex and more lift for 600hp at 6600.
There would be other factors as well I suspect.
steve c
1980RS
Expert
Expert
Posts: 806
Joined: Thu Oct 13, 2016 10:03 am
Location:

Re: 383 sbc first dyno experience

Post by 1980RS »

steve cowan wrote: Sat May 14, 2022 3:15 am
1980RS wrote: Sat May 14, 2022 12:11 am
steve cowan wrote: Fri May 13, 2022 9:55 pm
Thanks Bob.
At my weight 3650 with me
Moroso slide says 10.6s@126mph
Larry's pipemax says 10.70 @ 125 mph at approx 580hp
That sounds right to me. One thing I will note was that on a test with the 300-36 dual plane vs the 300-25 strip dominator I thought the 300-36 was better ET wise and mine was with no porting and only 1 mph difference. I also know last fall that my Air Gap with the divider cut all the way down really worked good, so there's a couple of more options at the track if you don't hit your goal.
Good information there Bob ,
So there are 2 schools of thought with the small intake port/valve combination -
So as rpm increases so does port velocity but the limit is around 0.55 mach - 690ft/sec
For this engine to peak at around 6500-6600rpm and hang on is the port shaped well to handle the speed??
Or is the ported intake manifold a baidaid
Runner opening at intake is 3.13" and 2.25" at the flange this is with radius taken into account.
Pushrod pinch is 2.05" throat is 2.27" includes stem factored in
Thoughts ??
Here is a result form back in the late 90's when I ran my 406 with a set of Sportsman II heads I used. The 300-25 Holley ran the best of 11.01@123mph. My 2925 Super Victor ran 10.82@120.5mph. Both intakes at the time were out of the box models.
econo racer
Expert
Expert
Posts: 709
Joined: Mon Nov 26, 2007 11:44 pm
Location:

Re: 383 sbc first dyno experience

Post by econo racer »

Steve I always try different things some times not needed #-o I would like to see what the RPM intake and 1.5 intake rockers would do just for the fun of it. Naturally one change at a time/ But some times I am that guy that should leave it a lone :D My 400 sbc lost 3 tenths or more trying the SVJ intake. Went back with the rpm and back to being faster. In all fairness I did not try any jet changes or anything else.
HQM383
Member
Member
Posts: 140
Joined: Sun Sep 12, 2021 7:25 am
Location: Down under

Re: 383 sbc first dyno experience

Post by HQM383 »

steve cowan wrote: Sat May 14, 2022 4:53 pm
HQM383 wrote: Fri May 13, 2022 10:54 pm
steve cowan wrote: Fri May 13, 2022 10:20 pm
Jamie,
105 ICL,
I wanted to test ICL on dyno but boys said it will only rock the curve up or down and probably not show power increases??
Because my car heavy the suggestion was to test at the track
105* ICL, there it is in post 1. I should have checked.

Did you get a VE figure?
I played around with pipemax
522 tq but shows 600hp
At 6600rpm using 114 % VE
shows level 10 on tq but level 7 on hp if I am understanding it correctly.
Hope that makes sense.
Pipemax shows 256 @ 0.050 in and 264 @ 0.50"ex and more lift for 600hp at 6600.
There would be other factors as well I suspect.
In the last selection what engine type did you choose for that cam?
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

1980RS wrote: Sat May 14, 2022 5:06 pm
steve cowan wrote: Sat May 14, 2022 3:15 am
1980RS wrote: Sat May 14, 2022 12:11 am

That sounds right to me. One thing I will note was that on a test with the 300-36 dual plane vs the 300-25 strip dominator I thought the 300-36 was better ET wise and mine was with no porting and only 1 mph difference. I also know last fall that my Air Gap with the divider cut all the way down really worked good, so there's a couple of more options at the track if you don't hit your goal.
Good information there Bob ,
So there are 2 schools of thought with the small intake port/valve combination -
So as rpm increases so does port velocity but the limit is around 0.55 mach - 690ft/sec
For this engine to peak at around 6500-6600rpm and hang on is the port shaped well to handle the speed??
Or is the ported intake manifold a baidaid
Runner opening at intake is 3.13" and 2.25" at the flange this is with radius taken into account.
Pushrod pinch is 2.05" throat is 2.27" includes stem factored in
Thoughts ??
Here is a result form back in the late 90's when I ran my 406 with a set of Sportsman II heads I used. The 300-25 Holley ran the best of 11.01@123mph. My 2925 Super Victor ran 10.82@120.5mph. Both intakes at the time were out of the box models.
Interesting swing in et and mph with manifolds for sure,it is no secret the SV as cast is very average at best but ported and runner lengths for application it responds well,seems the newer SV 2814 for the vortec head has a better plenum as cast.
20211024_112028.jpg
20211024_112044.jpg
20211024_181439.jpg
Pictures of as cast SV , 300-25 and a plenum modified SV .
Look at the inside dividers I am holding the plenum,look at the area differences.
But also have to consider length of intake runners ,area at both ends ,taper in the runner,height and actual area the plenum holds.
What I do know is measurement taking,calculating radius correctly, porting on intake manifolds is an extremely difficult job,that I do know :D
You do not have the required permissions to view the files attached to this post.
steve c
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

econo racer wrote: Sat May 14, 2022 6:15 pm Steve I always try different things some times not needed #-o I would like to see what the RPM intake and 1.5 intake rockers would do just for the fun of it. Naturally one change at a time/ But some times I am that guy that should leave it a lone :D My 400 sbc lost 3 tenths or more trying the SVJ intake. Went back with the rpm and back to being faster. In all fairness I did not try any jet changes or anything else.
I am not sure without testing for myself but other 383 sbc with around same torque figures were down a ways with airgap after peak torque and / or the peak torque was at a lower rpm.say you want your engine to peak at 6500 rpm you need peak tq at 5000rpm.
For a NA engine that 1500rpm spread between peaks is pretty close I think.
My peak torque was 5300 rpm and peak hp 6600rpm and the reason it did not peak higher could be a number of things but I think port area plays a big part.
Using more duration might of pushed peaks up higher maybe..
I personally can't see a airgap holding onto power past peak but I am wrong alot :D .
Now talking about going to a 1.5 rocker on the intake I would like your opinion on what might happen.
I have my own theory but would like yours first,
A couple of things to consider-
Short cam timing on intake
5.7" Conrod
50 degree seats on intake and exhaust
Small fast port and smaller valves than most would consider in general.
Only has 11.45:1 compression but MS109 fuel is being used for a reason.
Please don't take my comments as arrogant or disrespectful as I am interested in everyone's opinions and thoughts, we are all here to learn.
steve c
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

HQM383 wrote: Sat May 14, 2022 6:52 pm
steve cowan wrote: Sat May 14, 2022 4:53 pm
HQM383 wrote: Fri May 13, 2022 10:54 pm

105* ICL, there it is in post 1. I should have checked.

Did you get a VE figure?
I played around with pipemax
522 tq but shows 600hp
At 6600rpm using 114 % VE
shows level 10 on tq but level 7 on hp if I am understanding it correctly.
Hope that makes sense.
Pipemax shows 256 @ 0.050 in and 264 @ 0.50"ex and more lift for 600hp at 6600.
There would be other factors as well I suspect.
In the last selection what engine type did you choose for that cam?
I will get back to you on that,have to revisit
steve c
1980RS
Expert
Expert
Posts: 806
Joined: Thu Oct 13, 2016 10:03 am
Location:

Re: 383 sbc first dyno experience

Post by 1980RS »

steve cowan wrote: Sat May 14, 2022 8:35 pm
1980RS wrote: Sat May 14, 2022 5:06 pm
steve cowan wrote: Sat May 14, 2022 3:15 am
Good information there Bob ,
So there are 2 schools of thought with the small intake port/valve combination -
So as rpm increases so does port velocity but the limit is around 0.55 mach - 690ft/sec
For this engine to peak at around 6500-6600rpm and hang on is the port shaped well to handle the speed??
Or is the ported intake manifold a baidaid
Runner opening at intake is 3.13" and 2.25" at the flange this is with radius taken into account.
Pushrod pinch is 2.05" throat is 2.27" includes stem factored in
Thoughts ??
Here is a result form back in the late 90's when I ran my 406 with a set of Sportsman II heads I used. The 300-25 Holley ran the best of 11.01@123mph. My 2925 Super Victor ran 10.82@120.5mph. Both intakes at the time were out of the box models.
Interesting swing in et and mph with manifolds for sure,it is no secret the SV as cast is very average at best but ported and runner lengths for application it responds well,seems the newer SV 2814 for the vortec head has a better plenum as cast.20211024_112028.jpg20211024_112044.jpg20211024_181439.jpg
Pictures of as cast SV , 300-25 and a plenum modified SV .
Look at the inside dividers I am holding the plenum,look at the area differences.
But also have to consider length of intake runners ,area at both ends ,taper in the runner,height and actual area the plenum holds.
What I do know is measurement taking,calculating radius correctly, porting on intake manifolds is an extremely difficult job,that I do know :D

I do know that in Aug of this year I will be testing my ported Vic Jr. over the Air Gap that ran 11.30 on the button. Should interesting but I hope it's a better teat than my BBC test was in 2019. Ported Air Gap vs my ported Strip Dominator, .003 difference and about a 1 mph, wasn't worth the gaskets :lol:
steve cowan
Guru
Guru
Posts: 1665
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: 383 sbc first dyno experience

Post by steve cowan »

1980RS wrote: Sat May 14, 2022 9:38 pm
steve cowan wrote: Sat May 14, 2022 8:35 pm
1980RS wrote: Sat May 14, 2022 5:06 pm

Here is a result form back in the late 90's when I ran my 406 with a set of Sportsman II heads I used. The 300-25 Holley ran the best of 11.01@123mph. My 2925 Super Victor ran 10.82@120.5mph. Both intakes at the time were out of the box models.
Interesting swing in et and mph with manifolds for sure,it is no secret the SV as cast is very average at best but ported and runner lengths for application it responds well,seems the newer SV 2814 for the vortec head has a better plenum as cast.20211024_112028.jpg20211024_112044.jpg20211024_181439.jpg
Pictures of as cast SV , 300-25 and a plenum modified SV .
Look at the inside dividers I am holding the plenum,look at the area differences.
But also have to consider length of intake runners ,area at both ends ,taper in the runner,height and actual area the plenum holds.
What I do know is measurement taking,calculating radius correctly, porting on intake manifolds is an extremely difficult job,that I do know :D

I do know that in Aug of this year I will be testing my ported Vic Jr. over the Air Gap that ran 11.30 on the button. Should interesting but I hope it's a better teat than my BBC test was in 2019. Ported Air Gap vs my ported Strip Dominator, .003 difference and about a 1 mph, wasn't worth the gaskets :lol:
I have done that testing with airgap/ open plenum manifolds on 450/500 hp engines and its a wash.
There will be a cross over point in power where that test becomes invalid in my opinion.
I am porting a Vic jnr at the moment for my cruiser 383 combo,the Vic will be a reasonable intake once done but needs alot of work.
Last year when my car run 11.1s they are the same heads/ valve job from 182cc to 186cc most material from roof and pinch but we talking 4cc.
Close to same compression,similar cam as in specs 241-251 @0.050".600" - 570" net lift 1.6"-1.5" rockers 104ICL 108 LSA.
Intake valve speed faster now obviously.
Cleaned up Vic jnr not ported but port match good.
950hp carb,now 850 hp carb but using same throttle plate,metering blocks,same emulsion pack at the moment.
34 degrees timing.
50/50mix 109 / 98 pump .
It takes around 500hp to run 11.1 at 3650 pounds.
So where is the 70hp come from??
Better ring seal with dart block?
Smaller ring pack and lighter oil ring 4 pound compared to 12 pound ?
Used vac pump on both
Ported 300-25 compared to stock victor?
Bigger carb.?
There is approx 80" more lift on intake and 20" more on exhaust.
I think you can get 1 and 2hp and 4 and 5hp here and there .
Or was my 010 block motor not tuned up :D
steve c
Post Reply