I dynod my 355 tested several things I am sharing

[GARY C]

Did both sets of headers have merge collectors or just the 1.875 headers?

The bigger headers were straight collectors.

Did you get to test different collector lengths?

[Carnut1]

I like the spacers, I will guess a 1" tapered into a 1" open. Thsnks, Charlie

[statsystems]

Because I'm old, can I go over this a bit just for clarity for me?

The big headers were 1.875-2.00 stepped with a straight 3.5 collector and the other headers were 1.750-1.875 with a 3 inch merge collector?

I'm trying to get it straight in my pointy little head.
[/quote]


Yep...

"Changed headers to 1 3/4 to 1 7/8 with a merge collector 3inch it lost 4hp. I tried different jetting it was solidly down."




Jeff
[/quote]


Thanks. That what I thought I read but just checking.

[David Vizard]

Here is the combo
355sbc
4.030x3.48
11.97 compression ratio
My ported Brodix Dragon Slayer head 241cc 2.63csa 2.08/1.6 valves hollow stem intake valve they flowed 322cfm on a 4.030 bore
Ported Brodix Bm100 intake
1000cfm Race demon carb used as gas and methanol
252/258@ 0.050 108LSA installed at 106 .780/.688 cam
Best headers 1 7/8 stepped to 2inch with 3.5inch collector
No vacuum pump or evac set up.

Here is how it went and some reasons. First I built a 355 because I wanted a test engine that I wouldn't feel bad if it blew up or sucked. I had this 355 because I used it in the 2007emc. The cylinders got honed and installed longer 6inch rods and SRP proffesional series pistons with a small dome. All other parts were picked because I wanted to test things. For instance 241cc should be way too big according to the internet for a 355. I wanted to see what it would really do. I had never used this new brodix intake so why not try using it. The cam I had never used the QRI lobes so time to try that. Is methanol really that much better than gas? I wanted to find out? What about bigger headers hurting power. I had heard several things that on the internet that from previous testing hadn't shown to be correct for me. Let's just see.

The dyno actually started on a down side within 2minutes of firing it a loud squeal was heard. Shut it down and found out the roller cam button in the Cloyes timing cover had failed. Changed that and started making runs. Initially it was on 91octane Casey gas station gas. Timing was at 30degrees. First pulls were 3500-5500. When it first loaded it would slightly rattle but then went away. As the pulls kept increasing in rpm we raised the lower limit too. Then it never did it again. So that pump gas will work with this compression ratio but you have to take out timing down low. Here is a run down of tests and there changes.

Timing from 30 to 33 degrees netted about 50hp
Timing from 33 to 36 degrees netted 10hp it was left there for the rest of the testing.
I added the race gas additive to bring the octane to 98 it gained 2hp
Changed headers to 1 3/4 to 1 7/8 with a merge collector 3inch it lost 4hp. I tried different jetting it was solidly down.
Switched the race demon to methanol. (you change boosters, metering blocks, bleeds, squirters, needle and seat) It gained about 10hp and 20ft lbs of torque
Peak torque gas was 515tq@ 6100rpm
Peak torque methanol was 537.5@5900-6000rpm
Peak horsepower gas 662hp@7300rpm
Peak horsepower methanol 672.6@7400rpm

Strange thing though when it was fat on methanol to begin with it made its best torque at 542.

I made about 20 pulls 15 were between 5500-7500 rpm
I did make a couple of pulls on gas to 7800rpm it went like this(This was with the smaller headers)
7000-646
7100-649.9
7200-653.2
7300-654.8
7400-656.3
7500-656.0
7600-654.8
7700-650.9
7800-648.1

It hung in good.

It probably has a 680 in it but I had to be somewhere in the evening and called it quits. The EGTs were just starting to get to 1050

I would love to post pics but without photobucket I have no idea how.

Well Eric I am sure I won't get any negative response to this:- Damn good effort!
DV

[WeingartnerRacing]

The s10 is far from being ready for the motor. It is just going to be a cool street toy.

Carnut here is the flow sheet. This is with no exhaust pipe.

[Carnut1]

Eric, I can estimate flows at.05" lifts but I will need flange dimentions, corner radiuses on ports, exhaust port length, exhaust throat diameter. Thanks, Charlie

[RCJ]

What did the afr curve look like.Was it getting richer as the rpm increased?What I've found is the motor will like to be rich to make peak torque ,then be leaner at higher rpm to make peak hp.I have not been able to get a carb to make that curve yet.

[turdwilly]

It would probably make 700 if not for that yellow paint

[David Vizard]

The s10 is far from being ready for the motor. It is just going to be a cool street toy.

Carnut here is the flow sheet. This is with no exhaust pipe.

Charlie,

This looks good. Are you going to post IOP graphs or do you want me to do it??
DV

[Carnut1]

I would be glad to do it after I get all the info. If you have all the info you are welcome to post. I may not get to it right away. Thanks, Charlie

[TBART1970]

It would probably make 700 if not for that yellow paint

Hey, I had a yellow 406 for years. Great engine.


(Everybody else hated the yellow)

[WeingartnerRacing]

Intake opening is. 1206 with 1/2 radius. The Exhaust throat is 1.408 diameter exhaust port length was 3.5.

[WeingartnerRacing]

What did the afr curve look like.Was it getting richer as the rpm increased?What I've found is the motor will like to be rich to make peak torque ,then be leaner at higher rpm to make peak hp.I have not been able to get a carb to make that curve yet.

Rich at start then slightly leaner then rich by the end but not huge variation. I needed more time but ran out.

[77cruiser]

Nice job Eric!

[statsystems]

What did the afr curve look like.Was it getting richer as the rpm increased?What I've found is the motor will like to be rich to make peak torque ,then be leaner at higher rpm to make peak hp.I have not been able to get a carb to make that curve yet.

Rich at start then slightly leaner then rich by the end but not huge variation. I needed more time but ran out.

You never have enough time on the dyno. Once you get going and start making changes, you see four other changes that need to be tested. In the end, you just flog what you can.