400-470 stroker build--results

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RAMM

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Like title says , I thought seeing what went into this build would be of interest to some so here is what it took to build a budget conscious Mopar stroker for use in the 2013 EngineMaster's Challenge.
The 3 main rules were 3000-7000rpm test range, hydraulic lifters, 11.5 comp, 1.75" throttle bore carb (Holley 950 Hp)

At the contest it made peaks of 755 hp and 674 lbs.

Rundown: 400 block circa '75 (short fill), stock steel 440 crank final cubes came in @ 466
Bore 4.361"
Stroke 3.900" (small error in offset resulted in .015" less stroke)
6.135" Scat BBC rods
Icon 826 pistons with 1.867" CHT
CompCam roller 256/260 @.050" .750/.708" 106 LSA
Custom 1/2" girdle with aluminum main cap spacers
internal oil p-u 1/2" NPT
Cloyes Hex-Adjust timing set
ProComp heads 2.25" (hollow stem) 1.75"
Indy 400-2 intake
Schoenfeld 1 7/8-2" dyno/sprintcar headers

This was to be our development engine to beat on trying different parts/configs. I had most of these parts on hand and wanted to get it together, test things out and then build a copy with much nicer parts and a few more tricks with what we learned testing this one.
I had this engine running late August and was surprised it made pretty good power considering the low buck nature of it. Our first test up to 6500 rpm netted peaks of 708 hp/638 ft/lbs @ 32 total.
Our first pull to 7000 rpm dropped to 508 hp @ 7000 rpm! Due to lifter instability.

This engine is absolutely wicked and revs like an ultralight smallblock. It becomes even more impressive when you consider that it uses a single Holley 950/hydraulic roller lifters/and a 256 @ .050" camshaft.



I know I am forgetting things to post about this build. Ask away. J.Rob

Here's the link with a couple of photos.

http://www.popularhotrodding.com/en...y_coverage/robinson_ruttler_auto_machine.html
 
Sweet build Jesse!
I don't know much about the engine masters builds, are they to run on pump swill or do ya run them on C12-C16?
I'll have to get the mag when it comes out.
 
DAMN! Those heads/intake must have been flowing a Bunch. Is that a hydraulic roller grind? I have never seem .750" lift in a hydraulic cam.

Impressive!
 
66 Dartman said:
Sweet build Jesse!
I don't know much about the engine masters builds, are they to run on pump swill or do ya run them on C12-C16?
I'll have to get the mag when it comes out.
Click to expand...

Vp fuels are the fuel sponsor for the event and all engines are run on Vp100 StreetBlaze. It is billed as a pump type fuel. It is pretty good stuff and it stains everything in the intake tract orange. J.Rob
 
MRL Performance said:
DAMN! Those heads/intake must have been flowing a Bunch. Is that a hydraulic roller grind? I have never seem .750" lift in a hydraulic cam.

Impressive!
Click to expand...

The heads moved 360cfm at peak and the Indy manifold was pretty heavily worked. The cam is a solid grind but hydraulic rollers in a short travel design were used with zero preload. Thanks --It really is a super strong package. J.Rob
 
What's the reasoning behind the short rod / tall piston in this stroker? Parts on hand?
 
80fbody said:
What's the reasoning behind the short rod / tall piston in this stroker? Parts on hand?
Click to expand...

Glad you caught that. The idea is higher piston speeds approaching and leaving TDC. Also tall pistons are stable. The pistons were only a little over 600grams. J.Rob
 
Nice. Would you conclude that this rod combo should produce a little more horsepower than the 6.535" rod due to that increased speed. Torque would possibly come down correct?
 
Very cool. Personally I like the idea of a shorter rod motor if the heads are good enough.
Were the rod journals left at mopar width? I'm working on a B wedge 496 project and looking at shorter BBC rods but concerned about the side clearance.
 
So a stock 440 crank made/handled this? Wow. great combo.
 
80fbody said:
Nice. Would you conclude that this rod combo should produce a little more horsepower than the 6.535" rod due to that increased speed. Torque would possibly come down correct?
Click to expand...

I tend to think it would react opposite to what you wrote. More intake tract velocity at lower rpm should produce greater torque below the torque peak. J.Rob
 
moper said:
Very cool. Personally I like the idea of a shorter rod motor if the heads are good enough.
Were the rod journals left at mopar width? I'm working on a B wedge 496 project and looking at shorter BBC rods but concerned about the side clearance.
Click to expand...

Journals were left Mopar width. Side clearance was .043" --no big deal at all. J.Rob
 
dukeboy_318 said:
So a stock 440 crank made/handled this? Wow. great combo.
Click to expand...

So far it is taking it just fine--I have over 60 dyno pulls on it. The crank was worked extensively. Welded up undercuts/counterweights reduced .350"/profiled/smoothed/offset ground/balanced etc..... Lots of work. J.Rob
 
Going a little deeper in terms of intake tract velocity - do you think it's a case of the shorter rod starting the "pull" earlier than a similar long rod engine?
My feeling is with a larger port volume design (race-type full porting) low lift flow is typically sacrificed for peak numbers at max lift. The short rod combo should "pull" harder earlier in the lift cycle in most cases which helps minimize the effect of that compromise.
 
RAMM said:
The cam is a solid grind but hydraulic rollers in a short travel design were used with
zero preload. Thanks --It really is a super strong package. J.Rob
Click to expand...
So.....If I wanted to run on the street with an even milder solid roller grind
(630 - 660 lift) and use the short travel hydraulic roller tappets would you,
based on your experience, consider it to be super reliable?
 
moper said:
Going a little deeper in terms of intake tract velocity - do you think it's a case of the shorter rod starting the "pull" earlier than a similar long rod engine?
My feeling is with a larger port volume design (race-type full porting) low lift flow is typically sacrificed for peak numbers at max lift. The short rod combo should "pull" harder earlier in the lift cycle in most cases which helps minimize the effect of that compromise.
Click to expand...

This is exactly what my logic and experience tells me. Earlier and harder followed by fast approach for more turbulence (better mixing and detonation supression). Every long rod engine I ever built underperformed for what it was. J.Rob
 
Old Man Mopar said:
So.....If I wanted to run on the street with an even milder solid roller grind
(630 - 660 lift) and use the short travel hydraulic roller tappets would you,
based on your experience, consider it to be super reliable?
Click to expand...

With a milder grind as you state I would not hesitate to use this setup. As long as your initial preload adjustments are accurate it should be super reliable. J.Rob
 
the motor would be damn reliable.

6500 rpm netted peaks of 708 hp/638 ft/lbs @ 32 total

better make sure your drive train is up to the task lol
 
Considering there is only .015" total plunger travel-you have to be very certain not too preload too much. Also keep in mind the aluminum heads will change this dimension as they come up to temperature. In this case preload was pretty much zero-when hot. J.Rob
 
Got it.

Never considered the aluminum expansion factor (this is why you are the expert).

What measurement would you recommend on initial cold start-up to get it hot for
the first time so you can set the zero lash hot?

Thanks.
 
Old Man Mopar said:
Got it.

Never considered the aluminum expansion factor (this is why you are the expert).

What measurement would you recommend on initial cold start-up to get it hot for
the first time so you can set the zero lash hot?

Thanks.
Click to expand...

out of curosity, what rocker arm set up are u running on this?--------thanks, bob:coffee2::coffee2:
 
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