383 sbc first dyno experience

[KnightEngines]

Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.

Short of pouring a mold, can a guy get in there with a pair of inside dividers and get a measurement that way?

That's all I use, multiple dividers set to the critical dimensions to use while porting.

[skinny z]

Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.

Short of pouring a mold, can a guy get in there with a pair of inside dividers and get a measurement that way?

That's all I use, multiple dividers set to the critical dimensions to use while porting.

Sounds logical.
I'll be the reverse of that using the dividers to determine the width and height of the MCSA and other points of interest.
Thanks.

[steve cowan]

Has anyone had any experience with total seal gas ported top ring?
I just ordered a set
1.2mm gas ported
1.5mm napier
3mm low tension
Looking at going back on the dyno after Xmas
Using same cylinder heads but will look at modifying with more porting, steeper valve job,angle mill for a bit more compression
A bit more camshaft as in duration around 250ish on intake lobe and as much lift as possible.
I just ordered a TFS 32400111 intake manifold that I will port as well.
My main interest at the moment is why engine lost power with more vacuum, and I am curious if the gas ported top ring will help with that .
Appreciate any feedback.

[KnightEngines]

Has anyone had any experience with total seal gas ported top ring?
I just ordered a set
1.2mm gas ported
1.5mm napier
3mm low tension
Looking at going back on the dyno after Xmas
Using same cylinder heads but will look at modifying with more porting, steeper valve job,angle mill for a bit more compression
A bit more camshaft as in duration around 250ish on intake lobe and as much lift as possible.
I just ordered a TFS 32400111 intake manifold that I will port as well.
My main interest at the moment is why engine lost power with more vacuum, and I am curious if the gas ported top ring will help with that .
Appreciate any feedback.

Steve - better to use actual gas ports, lateral works fine & they don't carbon up like vertical ports.
You want more cam, 250 @ .050 is a street cam!
You have 5000+ converter stall, you plain ol don't need to be shy with the cam, let it eat!
I'd jam a 268/274 on 109 in it with .440/.420 lobes.

[steve cowan]

Has anyone had any experience with total seal gas ported top ring?
I just ordered a set
1.2mm gas ported
1.5mm napier
3mm low tension
Looking at going back on the dyno after Xmas
Using same cylinder heads but will look at modifying with more porting, steeper valve job,angle mill for a bit more compression
A bit more camshaft as in duration around 250ish on intake lobe and as much lift as possible.
I just ordered a TFS 32400111 intake manifold that I will port as well.
My main interest at the moment is why engine lost power with more vacuum, and I am curious if the gas ported top ring will help with that .
Appreciate any feedback.

Steve - better to use actual gas ports, lateral works fine & they don't carbon up like vertical ports.
You want more cam, 250 @ .050 is a street cam!
You have 5000+ converter stall, you plain ol don't need to be shy with the cam, let it eat!
I'd jam a 268/274 on 109 in it with .440/.420 lobes.

I have that comp roller I sent to crow to spread the centres 2 degrees, I have not used that cam yet.
It's a bit light on intake lobe but if I can be around 12.1 comp might work.
266 - 272 @ 0.050"
.416 - .420 lobe
707"/ 1.7 RR - 630"/1.5 RR
108 LSA.

[KnightEngines]

Has anyone had any experience with total seal gas ported top ring?
I just ordered a set
1.2mm gas ported
1.5mm napier
3mm low tension
Looking at going back on the dyno after Xmas
Using same cylinder heads but will look at modifying with more porting, steeper valve job,angle mill for a bit more compression
A bit more camshaft as in duration around 250ish on intake lobe and as much lift as possible.
I just ordered a TFS 32400111 intake manifold that I will port as well.
My main interest at the moment is why engine lost power with more vacuum, and I am curious if the gas ported top ring will help with that .
Appreciate any feedback.

Steve - better to use actual gas ports, lateral works fine & they don't carbon up like vertical ports.
You want more cam, 250 @ .050 is a street cam!
You have 5000+ converter stall, you plain ol don't need to be shy with the cam, let it eat!
I'd jam a 268/274 on 109 in it with .440/.420 lobes.

I have that comp roller I sent to crow to spread the centres 2 degrees, I have not used that cam yet.
It's a bit light on intake lobe but if I can be around 12.1 comp might work.
266 - 272 @ 0.050"
.416 - .420 lobe
707"/ 1.7 RR - 630"/1.5 RR
108 LSA.

That will work, .700" is enough.

[HQM383]

I've been following this build with great interest and what has been acheived with valve size, mcsa and cam. Impressive and challenges some accepted norms.

Steve, Tony, educate me on a cam of roughly 266* @.050" operating range and the heads being used that have 1.94" int valve, average 2.10 mcsa and "let it eat". Your expierence tells you this will work so is it just a case of keeping the valves open longer for cylinder fill rather than find more power with increased rpm range?

Steve, I'm liking the look of that manifold yet Trickflow is saying for 220cc and above sbc heads. What is your thought process and expeirience with Holley 300-25 and Vic Jr told you in choosing this manifold? I wonder how different it is from a 300-110 and SV2?

[steve cowan]

I've been following this build with great interest and what has been acheived with valve size, mcsa and cam. Impressive and challenges some accepted norms.

Steve, Tony, educate me on a cam of roughly 266* @.050" operating range and the heads being used that have 1.94" int valve, average 2.10 mcsa and "let it eat". Your expierence tells you this will work so is it just a case of keeping the valves open longer for cylinder fill rather than find more power with increased rpm range?

Steve, I'm liking the look of that manifold yet Trickflow is saying for 220cc and above sbc heads. What is your thought process and expeirience with Holley 300-25 and Vic Jr told you in choosing this manifold? I wonder how different it is from a 300-110 and SV2?

Can't speak for Tony and I am far from an expert on anything but my thoughts out loud.
The rpm has to go up to make more power because I don't want to change valve sizes, if I was going to put a 2.02 - 1.6 valves I would bolt on my Ported 180 SHP and it would probably make 600hp.
So a bit more intake port work,bigger cam and intake bigger it might peak above 7000rpm. More area under the curve should fatten up torque and hp.if I angle mill those heads to approx 57cc it should give around 12.1 comp,I have not calculated that yet.
The 300-25 was actually sized and port matched for the Dart 180 heads,the SV not really close to fitting and I want to use that someday on my Dart 215 pro - 1 heads.the Vic jnr is for the trickflow heads and would be to small for this application I think.
Believe it or not but the TFS intake is $600 AU delivered from summit and I see 300-25 manifolds in Australia for over $800 if you can get one.
My thoughts are with the bigger intake I might not have as much porting to do and I can weld the intake if I choose or need to.
Plus I want to see what they look like.

[HQM383]

I've been following this build with great interest and what has been acheived with valve size, mcsa and cam. Impressive and challenges some accepted norms.

Steve, Tony, educate me on a cam of roughly 266* @.050" operating range and the heads being used that have 1.94" int valve, average 2.10 mcsa and "let it eat". Your expierence tells you this will work so is it just a case of keeping the valves open longer for cylinder fill rather than find more power with increased rpm range?

Steve, I'm liking the look of that manifold yet Trickflow is saying for 220cc and above sbc heads. What is your thought process and expeirience with Holley 300-25 and Vic Jr told you in choosing this manifold? I wonder how different it is from a 300-110 and SV2?

Can't speak for Tony and I am far from an expert on anything but my thoughts out loud.
The rpm has to go up to make more power because I don't want to change valve sizes, if I was going to put a 2.02 - 1.6 valves I would bolt on my Ported 180 SHP and it would probably make 600hp.
So a bit more intake port work,bigger cam and intake bigger it might peak above 7000rpm. More area under the curve should fatten up torque and hp.if I angle mill those heads to approx 57cc it should give around 12.1 comp,I have not calculated that yet.
The 300-25 was actually sized and port matched for the Dart 180 heads,the SV not really close to fitting and I want to use that someday on my Dart 215 pro - 1 heads.the Vic jnr is for the trickflow heads and would be to small for this application I think.
Believe it or not but the TFS intake is $600 AU delivered from summit and I see 300-25 manifolds in Australia for over $800 if you can get one.
My thoughts are with the bigger intake I might not have as much porting to do and I can weld the intake if I choose or need to.
Plus I want to see what they look like.

Nice looking intake and priced well for sure, less than an SV 2925. When I seen it I was ready to draw the credit card out of the holster but put the safety back on when the description said developed for the 230cc head. I’m assuming I would lose throttle response over the 2925 but I see what you are trying to achieve. I’ll be interested in your report of the new Trickflow manifold v the old Holley staple.

I guess with the cam I’m curious of how much more rpm extra .050” duration will get out of your combo with the 1.94” valve and what Tony’s experience has seen in that realm.

[KnightEngines]

It's a simple time/area thing.
Without changing capacity to make more power you either gotta cram more air in per rev or turn more rpm, or both.
Once you get much above 110% ve it's far easier to turn more rpm that to improve ve%.
To go from say 6500 to 7000rpm peak power requires about 8% more time/area, which doesn't sound like much, but actually requires quite a lot more cam!
Add in your intake lag at higher rpm & the cam requirements get bigger again.

In the 260's is where experience tells me steve wants to be.

I've put 278/284 in a 355 cube engine - not near as cranky as you'd expect.

[skinny z]

A related question I think: With regards to VE and improving it, what are you opinions on overlap and the exhaust induced induction (5th) cycle?

I'm in the camp of the right amount of overlap and good exhaust, as in tuned length open headers (track days) will give that boost in VE. Some of the math indicates a 10% improvement if the combustion chamber can be evacuated fully and the cylinder completely filled.

A lot of things in play here obviously but I hear very little from you gentleman in this regard. All things Gen 1 SBC related and in the CID range of the subject line (although I'm at 357).

[F-BIRD'88]

If its a "street strip" car would you not want to optimize the cam overlap and exhaust valve events to best work with the headers/exhaust system you are going to use?

The " best cam" may well be different for a closed high perf street exhaust system with mufflers than if with Open headers.

Its not that hard to build a Street exhaust system that is 0 loss and quiet enough to get past Po-Po.
Saves a fortune on header gaskets and pit time at the track "Race it like you drive it".
But that best cam may be a different "best cam".

[skinny z]

If its a "street strip" car would you not want to optimize the cam overlap and exhaust valve events to best work with the headers/exhaust system you are going to use?

The " best cam" may well be different for a closed high perf street exhaust system with mufflers than if with Open headers.

Its not that hard to build a Street exhaust system that is 0 loss and quiet enough to get past Po-Po.
Saves a fortune on header gaskets and pit time at the track "Race it like you drive it".
But that best cam may be a different "best cam".

I'm speaking of a track only deal. Open headers.
I don't care about the street in this case. I can keep the tight fitting system that's in play now and crack open the cut outs on track days.
And it's the cam in specific that I'll generate a new thread about when the time comes. I don't want to mess up Steve's thread with too much noise.

[steve cowan]

A related question I think: With regards to VE and improving it, what are you opinions on overlap and the exhaust induced induction (5th) cycle?

I'm in the camp of the right amount of overlap and good exhaust, as in tuned length open headers (track days) will give that boost in VE. Some of the math indicates a 10% improvement if the combustion chamber can be evacuated fully and the cylinder completely filled.

A lot of things in play here obviously but I hear very little from you gentleman in this regard. All things Gen 1 SBC related and in the CID range of the subject line (although I'm at 357).

Kevin,
My opinion is it is to hard to lock in a definite answer to your question.
This is where Larry's program gives a really good starting point on induction size including headers etc.
Then we have packaging within the vehicle to deal with as well.
If you look at photos of my combustion chamber I have done basically nothing to them except clean up and blend top cut to chamber transition.
The reality is I don't have the experience yet to know what chamber modifications and what they effect.
In the hands of Tony or Larry I am sure they would work some magic on them.
I wanted to test open headers this weekend compared to full 3" exhaust but we got rained out.

[skinny z]

Kevin,
My opinion is it is to hard to lock in a definite answer to your question.
This is where Larry's program gives a really good starting point on induction size including headers etc.

I wanted to test open headers this weekend compared to full 3" exhaust but we got rained out.

I think that last sentence is key to my question.
Certainly changes in the tune would be expected especially if scavenging is improved regardless of the shape of your combustion chamber But as suggested, improvements in chamber shape have shown improvements in VE by way increased high lift flow (as in Vortecs).

Regarding the induction, yes most definitely. That side of the cylinder head is every bit as important in tuning as witnessed by your extensive testing with spacers. I'll be going there as well however my immediate interest, once I'm back on track, is to get into this exhaust. It's always been crippling and there certainly are better results to come.

Anyway, hoping for sunny skies down under and some testing and analysis from you.

Thanks as always Steve.