408 build and results.

Whatsup1962

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Winter project hit its final stages on the dyno this month.
Was looking for a good street build to drop in the Demon that I could throw some spray on.
Sourcing parts over the Winter was not easy. I ended up sacrificing some on the camshaft and possibly some on the intake....nothing was available. My goal was 500/500 and exceeded and feel short at the same time. Motor seemed to like 35 degrees of total timing the best. Here is the info on the build and results.

Scat forged stroker kit - compression came out to 10.38 to 1
Trickflow out of the box heads.
Comp Cams Hyd Roller XR286HR - Dur@.050 236/242 Adv 286/294 - LSA 110 - lift .544/.541
Harland Sharpe 1.6 RRs
Air Gap knock-off port matched to heads.
Holley 750 dp with 1" spacer.

Should make the Demon....well a Demon.



Dyno print out.jpg


284015188_2053270861541325_4769895466122470991_n.jpg


View attachment 1715935630

Dyno graph.jpg
 
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PRH

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Looks good:thumbsup:

Pretty short duration cam, dual plane intake....... that’s going to kill off a little top end.
 

rumblefish360

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Missing 15 hp isn’t to darn bad since you didn’t get the cam you wanted. Though I like the cam. Very nice for the street.

Did you try various spacers under the carb?
Try a bigger carb?
Port match the intake deeply ported up the runner?

I wouldn’t be unhappy about the results. Bummed that I could get exactly what I wanted for during the parts gathering I’d be.
 

rumblefish360

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Thanks, I bought a rotating assembly years ago with the flat tops, looks like I'm going to need to run a fat head gasket to get my compression down.
What does your compression work out to be with the flat tops?
 

Whatsup1962

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Did you try various spacers under the carb?
Try a bigger carb?
Port match the intake deeply ported up the runner?
No to various spacers and bigger carb...... time was limited on the dyno. We did jet up the carb several sizes to get the AFR we were looking for.
The intake is port matched to the heads with a little internal work...not much though. I think there is some to be gained with the intake.
My backorder came in after the dyno session so I have a actual Edelbrock Air Gap for it now. Going to hog it out and port match that intake and put it on.
I wont be able to get it back on the dyno but my head will say I picked up 15hp :)
 

crackedback

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1" open spacer would likely put some more steam in it, even on the hogged out ede intake. Open is usually better than a 4 hole, a tapered 4 hole better than a cheap 4 straight hole. Cheap improvement throughout the range.
 

DNasty777

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What does your compression work out to be with the flat tops?

I don't have the block here to measure exactly, but at zero deck height the summit calc puts me at 14:1 with .045 compressed thickness and 11.45:1 with .120 compressed thickness. Which makes complete sense because with OPs +20cc dish the calc puts him at 10.36 with .045 gasket.
 

rumblefish360

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No to various spacers and bigger carb...... time was limited on the dyno. We did jet up the carb several sizes to get the AFR we were looking for.
The intake is port matched to the heads with a little internal work...not much though. I think there is some to be gained with the intake.
My backorder came in after the dyno session so I have a actual Edelbrock Air Gap for it now. Going to hog it out and port match that intake and put it on.
I wont be able to get it back on the dyno but my head will say I picked up 15hp :)
I’d do what crackedback said and what d call 15+ all day EZ. Use the tapered spacer as thick as hood clearance allows.
I don't have the block here to measure exactly, but at zero deck height the summit calc puts me at 14:1 with .045 compressed thickness and 11.45:1 with .120 compressed thickness. Which makes complete sense because with OPs +20cc dish the calc puts him at 10.36 with .045 gasket.
14-1!!!!

Yikes!!!!
 

cookietruck

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I don't have the block here to measure exactly, but at zero deck height the summit calc puts me at 14:1 with .045 compressed thickness and 11.45:1 with .120 compressed thickness. Which makes complete sense because with OPs +20cc dish the calc puts him at 10.36 with .045 gasket.

i would double and triple check those calculations
 

B3422w5

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I don't have the block here to measure exactly, but at zero deck height the summit calc puts me at 14:1 with .045 compressed thickness and 11.45:1 with .120 compressed thickness. Which makes complete sense because with OPs +20cc dish the calc puts him at 10.36 with .045 gasket.

i doubt your anywhere remotely close to 14 to 1 with flattops.
I have the Icon flattops. They are roughly 11.5 compression with a 70 cc head. 12.5 with a 60 cc head.
 

DNasty777

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i doubt your anywhere remotely close to 14 to 1 with flattops.
I have the Icon flattops. They are roughly 11.5 compression with a 70 cc head. 12.5 with a 60 cc head.

That's reassuring, what's the gasket thickness to get those numbers?
 

rumblefish360

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If he had the KB 191’s, that would be different. 11.20 cc dome.
 

gzig5

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No to various spacers and bigger carb...... time was limited on the dyno. We did jet up the carb several sizes to get the AFR we were looking for.
The intake is port matched to the heads with a little internal work...not much though. I think there is some to be gained with the intake.
My backorder came in after the dyno session so I have a actual Edelbrock Air Gap for it now. Going to hog it out and port match that intake and put it on.
I wont be able to get it back on the dyno but my head will say I picked up 15hp :)
I'd say you got a pretty good result. I'm planning for something similar. I know the AG is a good intake overall, but with the stout low end torque from the 4" crank wouldn't the Strip Dominator intake you are selling give a stronger top end, while still providing plenty of low-mid range torque?
 

Whatsup1962

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I'd say you got a pretty good result. I'm planning for something similar. I know the AG is a good intake overall, but with the stout low end torque from the 4" crank wouldn't the Strip Dominator intake you are selling give a stronger top end, while still providing plenty of low-mid range torque?
Great question. I know the advertised rpm range on the Strip Dominator is 4500-8000. I just figured it would take away to much low end for a street car. My convertor should flash around 3500.
 

PRH

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My .02......

Based on what I see the tq curve doing from 5800-6073rpm(loses 50ft/lbs), along with the air flow dropping off on the last two lines of the sheet.......coupled with a fairly fast rate cam profile and 1.6 rockers...... it appears there may be the onset of some lifter bleed down from 5800 and up.
If that’s the case, then the area of the powerband where you’d expect the racy single plane intake to really shine is handicapped by inadequate valvetrain control.

I think the 5000-5800 range could be slightly improved with a single plane, but I wouldn’t be expecting big gains above that point if there is a control issue.

What size are the headers the motor was tested with?
 
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justinp61

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Great question. I know the advertised rpm range on the Strip Dominator is 4500-8000. I just figured it would take away to much low end for a street car. My convertor should flash around 3500.

I've never seen a 4" stroked small block that was soft on the bottom unless there was a serious mistake made when selecting parts. Even with large cams they seem to be monsters down low, at least mine have been.
 

furrystump

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68DAE638-0758-4C46-8F7B-0EB5CB899254.png

If he goes flat top with a .027 gasket he is only 12.88 for 4.040 bore. I have made the change from the 20ish cc icon to the icon flat top. Hard to keep it under 12 to 1 with gaskets. I’m .010 in the hole and 62 cc chamber? .027 gasket, Comes in around 12.2? If he is really zero deck and 60cc thats a BIG gasket to get it to a street friendly number.
 

qkcuda

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I used that same cam in my 500 stroker. It made right around 100 ft/lbs and 100 HP more, with the same flat torque curve. The combination was not maxed out by any means, but it was a blast to drive on the street.
 

cpearce

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I actually expected more out of the Trick Flow heads, even taking into account the cam and intake. I'd have guessed a 500h.p plus engine all day.

Now, in an A body this is going to be an extremely fun engine on the street, no question about it. I just figured there would be more there with those heads.
 


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