Intake Swap on Stroker?

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jimmyray

jimmyray

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I have a 408 stroker (details below) in my 73 Duster, best 60' of 1.673 (slicks) and best 1/4 is 12.26 @ 109.59. I am shifting at 5500, as that seems the best rpm for the lowest time, thus far. Since I am shifting so low, have a "mild" cam and lower compression, I wonder if the M1 single plane airgap is too much intake for the motor. I have a Weiand Stealth (dual plane) sitting on the 340 that came out of the car. Do you think it would be beneficial to low end torque, and 1/4 mile times to swap to the Stealth? I know it won't flow as much, and will hurt top end, but since I'm shifting relatively early...

Thoughts?



Motor details:
408 cast crank stroker from Hughes
9.6:1 compression
93 Octane gas
mild port/polish on Edelnbrock al perf heads, closed chamber, fresh valve job
M1 single plane airgap with gasket match (heads too)
Holley 750 DP with proform center section, jetted 74/84, 3.5 power valve
Comp roller .544/.541 236/242 110 centerline
FBO ignition, ditributor curved to 16 inital, 34 total @ 2900 rpm
Hooker comp 1 5/8" headers (dented bottoms on driver side, naturally) 3" collector
3" pipes into/out of welded Summit 3" mufflers into a-body tips
3000 stall TCI streetmaster
727 manual reverse
3.73 sure grip in a narrowed Dana J
 
The track guys would know that one best.
Dyno wise, the intakes are about equal with the typical trade off's except the M-1 seems to cover more low end than other single plane intakes.

Dyno wise, they seem to do even better with a well tuned T-Q. But that's dyno. Actual may vary.

Wait for the been there done that crew.
 
Jim,
Do you know what the heads flow? With what you have listed the intake change will only be marginal at best, and may not show any gains.
The mufflers may be too restrictive, have you tried to run the car with open hedders to see if this changed the ET? I know from our testing that the Exh. system for the street is much much too restrictive for the track. And saying this that we had to jet the carb up greatly because it made the engine too lean and wouldn't run.
In all reality that carb may be too small for the engine in race trim due to the port volume and the CI of the engine. It sounds like the carb is setup for more of a street tune than race.
 
It does look like a nice street strip set up. Very torquey with good top end. 12.26 at the track is nice. IMO, It's gotta be a fun street car.
 
I don't think changing to a Stealth is going to help anything but the extreme bottom end and you maybe able to trick the M1 by going to a 4 hole carb spacer if you haven't allready. I would agree that you need more carb and I'd bump up your timing by 2 deg. and see if that helps. Your times look really good but you maybe able to gain 3 tenths.

Terry
 
Leave the intake, the dual will pick up the bottom a lot but won't help it rev up top.
A couple things.
3' exhaust into a-body tips????[2'] bad idea.
3.5 power valve in a stroker with only 241* at fifty and a roller at that?
What's the actual manifold vacuum at idle in gear?
750 will work but for your set up 830cfm minimum.
The headers work I'm sure but 1 3/4 primary tubes are what you need to have.=super comps or tti's

I know a guy in fontana with a 70 duster with a similar combo and he finally broke into 11.98 from the constant 12.-12.04 that he ran, he had 3.91 gear and a similar cam and intake.
 
BTW I like the total 'could fiddle the initial' timing but feel you have too much octane for the comp ratio and aluminum heads, do you know if it will detonate at that timing with say 87-89 octane?
 
Thanks for the great replies!

The heads are Edel Performer, and have been touched up by Indy, only a little cleaning on the intakes, gasket match and polish the combustion chamber (see pics below). The heads I bought used, and Indy says they are good for an extra 10% flow. Stock, I've read the Edel's flow 249 cfm @ 0.500" so +10% would be in the 274 range, but I am a little skeptical, but what do I know?

The guy I bought heads/intake/carb from was running a 408 stroker in a Duster, and was hitting mid 11's. He had more cam, higher compression (about a point), and a 4.1 gear, and a little more convertor. I say that to give a perspective on the carb. I have heard many opinions on carbs, some say what I got is plenty, others say I need more. The proform is supposed to flow 830 cfm. The only way to know is to test one, but I hate to spend the $$$ for a 950.

On the timing, I have had it as high as 38 degrees, but the best thus far is 34 degrees. I want to try lower at 32, but keep running out of time (at the track)

I went with the lower power valve because the motor wanted to die at the end of a run, or after a hard practice launch before the lights. I had a 6.5 in it, and a carb guy suggested the lower Power Valve may help the problem, and it did. Since the carb is not used on the street (really bad MPG!), figured it was ok. If you have contrary opinion/info on it's affect on the strip. I'm still learning, and am FAR from knowing it all!

Car runs around 10 inches vacuum at idle in gear 850 rpm.

The reducers on a-body tips were cut off, and the were welded (!) to the 3" pipe. It should not be a restriction. See Pic.

At some point, I want to do the following:
1. Heads to Bobby @ BJR to increase the flow
2. Swap pistons to higher compression
3. More Cam
4. TTI 1.75 headers
5. Maybe more convertor

With all of that, I should hope the care would be deep into the 11's.

Of course, all of that cost money, and with tution, camp, and other various expenses of the 4 women in my life, it can be troublesome to scape together the extra dough. Thus, I was investigating, cheap, non invasive ways to drop some time, I would love to dip into the 11's.

Last bit. I have actually run the car with 87 octane, and it ran fine, no detonation or preignition. With my cam, the dynamic compression calculates at 8.7 (see pic). I actually had not considered dropping the octane to run.

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If you go to a different intake, I'd do an Air gap or Performer RPM.

It will pick up the bottom end and not give up anything up top to the M1.
 
Jimmyray,I would not trust the dynamic calculation as corrrect,that doesnt add up with the static at 9.5 and the cam specs.There are many really good articles and calculators to be found and I ended up using this one http://members.uia.net/pkelley2/DynamicCR.html (the calculator is at the bottom and has alot more inputs for accuracy) the key is in the intake closing.According to your specs and using the above calculator your dynamic is actually 7.46,there are lots of opinions but a general rule is between 7.5 and 8.5 is ideal on pump gas.
 
It looks like you did not add 15° to the intake valve closing point on the calculator. Doing that I get 8:1, which is more believable to me. You package is soft. I have a ported 587 headed 422 that runs the same mph in a car 600lbs heavier, with a much smaller hydraulic flat tappet, a lower stall, and 3.23s. You should be into the 11s with what you have there. There's no way they got 10% out of a simple gasket match. I's say the heads probably would go in the 260 range as you have them. The 249 number is high by a little from what I've seen. Most land in the 240 area. I use a minimum of 870 wet flow cfm for a carb, I'd add a 1" open spacer if you can to the M1, if you can, blend the radius of the transition from carb gasket surface to ports. The dual plane won't help. I would have had at least a full point of compression higher and for that cam. For a tune up, most 4" arms and closed chambers like timing up to 32°. I think you may be trying to use more timing to help the soft low rpm issue, and that is hurting the peak power. I would reduce the centrifical to get a total of 32, and run 20° initial. It might help it both get moving, and pull harder in top gear. Also... TCI... bad move. They are mid grade, and have a lot of slippage in high gear with high torque engines. What is your trap rpm ?
 
I agree with moper but its still a pretty vague calculator,Ive done the math by hand many times and have struggled to find an accurate calculator to back up reality.One other that is a good one since it will line up with cylinder psi here http://www.rbracing-rsr.com/comprAdvHD.htm this way I was able to use quite a few known readings from various engines to verify the accuracy-kind of reverse engineering.One thing I found was that to get real world accuracy I needed to use the seat to seat specs for the intake closing-even when it called for the .050 numbers,every time it matched known cranking psi values and the long hand math calculations.Obvioulsy there is no perfection but this has worked well for me,but every one and every car is different.
 
Running more octane then required will slow you down and put more heat in the cylinder.
I see the heads have been gasket matched, what I could never understand is when head porters port around the pinch though it still ends up being pinched be cause they don't actually remove it like they should, especially on those heads, they just try and get air to bend around it when air really likes to go straight, lame if you ask me.
Those eddys flow out of the box 'according to edlebrock'
.300 188
.400 232
.500 249
.600 288
But these things are very inconsistent and usually need re machining.

I bet with your compression ratio you'd make more power with ported iron heads, you can change pistons or mill .030 off each head and put 2* more cam advance to raise it.JMO
The power valve issue is only a bandaid to the real problem, you need to take the carb to knowledgeable tuner and have the right air bleeds installed or like your jetting is telling me go with a bigger carburetor!
 
I would put a 950 HP holley on there with a 2" open aluminum spacer on manifold and another 2" 4 hole Phenolic spacer next to the carb. As for power valve go to 2.5's. Use Vp 113 fuel. Timing should be able to run in the 32 to 34 degree range. Do not need bigger cam infact one with less centerline degrees would be better say around 106. 110 valve center line is a lot for this stroker. Also need deeper gears and more stall in convertor.
I have a 340 20 over bore
3.79 stroke crank
6.123 rods
304/557 lift cam flat tappet
950 hp carb
open chamber iron heads
13 to one compression
VP113 oxygenated fuel
4200 stall convertor
4:88 gears
11.5 x 29.5 tires
in a 3550 1965 Barracuda that runs in high 10's
 
what if you raised the compression some also? thinner gasket? O and buy the tuning book by 4secondsflat.com
 
TheCrusher said:
Huh I thought dale earnhardt died, one things fo sho he wasn't known for being a 'tuner' wa. he he he 'joke'
Click to expand...
At my age I was racing as the intimidator long before he started to be famous and drive chebbies lol Was he racing back in the 60's?
 
intimidator said:
At my age I was racing as the intimidator long before he started to be famous and drive chebbies lol Was he racing back in the 60's?
Click to expand...

Cool stuff, one things for sure early on he drove a dodge, must have been instinct, then a chevy, must have been dollar signs.:toothy10:

Intimidator, this guy only has around 8.5 compression so the race gas aint gonna help him, don't ya think? :read2:
 
Intimidator, this guy only has around 8.5 compression so the race gas aint gonna help him, don't ya think? :read2:
Click to expand...

When I bought the setup from Hughes Racing, I told them my intentions for the car (street/strip, and gave them all of my info on cam, heads, etc. stressed that they were Edel heads with 65cc chambers, and they still recommneded the KB 356 pistons. After my trips to the strip, I call Hughes back and talked to Dave (talked to Tim at the start) and he agreed I should have got the KB 744, which would have bumped up compression about 2 points. Water under the bridge now, and if I would have known then, what I know now...

Anyhoo, the thoughts on playing with the cam are interesting. Currently, the cam is set to the card specs with a 105.5 centerline (could not hit 106 exactly). I did a compression check and got between 170-180 on all cylinders, which is close to Hughe's calculations (see below). Tim's mentioned several times that cylinder pressure was more important than calculated compression ratio, which I can understand, but from what I've read it should be closer to 200 psi for AL heads.

It is a factory roller block, so I went with a roller cam. Hughes recommended one of their grinds, but it was $160 more than the comp cam, and had more seperation on the lobes at 114 vs. 110 for the Comp I installed.

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According to Hughes Engines web site,i think it was(dont stone me if im wrong)They reccomend the stealth over the M1 for a street/strip engine,with very minor work of course.Its actually about the same height as the M1,just needs the bottom of the runners straightened slightly,and has an rpm range from idle to near 7000 rpm with the mod listed.Might want to check there website,they have good info on all the Intakes everybody is telling you about.Heck,if you have a stealth already,why not stick it on and see what it does?
 
I think a dual plane would pick up 25ftlbs of torque in the low rpm but turn into a light switch in the upper, but hey it's fun to try different things and learn first hand.

I have the kb356 and am not optimistic about the comp ratio I'll end up with by using the cam I have chosen which is boarder line in my case .575 282* 110cl but as small as I was willing to go.
But hey if your ending up with 170-180psi then sheeesh I feel a whole lot better thats for sure and wanna say to you, run the correct octane & get a bigger lift cam or 1.6 rockers and get them heads to breath.
 
Hughes uses cylinder pressure. That's the same calculations burntorange is using, and the KB dynamic compression calculator uses. I agree, the minimum pressure should be 200, an with a dynamic of 8.6 (I agree burnt, this is somewhat of a generalization figure) it would be closer to 220-225. That VP fuel is oxygenated, so it's a little misleading as to it's affects. But there's no way race fuel ads heat. Just the opposite. The lowest octane that provides for 0 detonation will make the most heat in the shortest time (in terms of crankshaft degrees) and should everything be designed right so that heat hits at just the right time, it will make the most power. I had carb issues (defects in teh metering block) and switching to C-16 (VP fuel for superchargers... it's oxygenated) from C-12 (std 110 octane leaded) picked the car up 2mph with no other changes...lol.
 
What I was saying is that too much octane or more than required will end up burning SLOWER therefore=more heat.
Running too rich will cool it down to an extent.
 
Slower is less heat energy used to move the piston tho... It's more of a slow controlled burn with race fuels.. so max pressure happens when the builder wants it to. But slower means more time for heat to get into the cooling system, and having to start the flame front earlier (more timing) risking more unmixed/liquid fuel in the chamber which also means less power produced for each firing event. that's why you see high static ratios with high octane fuels. The higher pressure builds more heat into the cooler burning fuel but allows the burn to be controlled better so max cylinder pressure hits the crank as it has the maximum leverage on the throw. Rich always shows cooler. I have my gueses on why, but I've never really looked into it...lol.
 
Higher octane number ='s burning faster?
I keep mixing it up.
 
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