408 Stroker

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scampmehard

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I just had my motor dyno

370lb TQ @ 2100 RPMS

MAX 500lb TQ @ 5100 RPMS

MAX 451HP @ 5800 RPMS

Are these good number for SB motor or could i have gotten more power you think..

My set up:

My roller assembly is all forged with 10.5:1 COMP
RHS Heads: Stage 3 port with match port on intake Air gap dual plane intake
Stainless steal valves, HD double valve springs, double roller rockers on roller shaft.
MuthaThumper Cam Mechanical/roller cam
Cam SPEC Duration: INTAKE 299 EXAUST 319 Lift @.50 INTAKE 243 EXAUST 257 Lob Sep: 107 DEG
750 CFM holly DBL pumper
Dougs race headers
4speed Trans
8 3/4 with 410gears and a spool.
 
Engine or chassis dyno?

Carb is too small for max power.

Cam is probably hurting you too.
 
Engine
What size carb you think i should go with.

So i should have not went with the Mutha tumper.



LXguy said:
Engine or chassis dyno?

Carb is too small for max power.

Cam is probably hurting you too.
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IF that is rwhp thats is awsume, if it's at the crank I agree with LXguy bigger carb would have gotten better numbers, I dont see any problem with the thumper cam, thats what I have they make good power, not enough people have used them so noone knows how well they work......yet, did you get your heads from Brian @IMM ??
 
I got the heads from RHS direct.

What size crab and what carb you think i should go with.
It crank.


412 Stroker said:
IF that is rwhp thats is awsume, if it's at the crank I agree with LXguy bigger carb would have gotten better numbers, I dont see any problem with the thumper cam, thats what I have they make good power, not enough people have used them so noone knows how well they work......yet, did you get your heads from Brian @IMM ??
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[ame="http://www.youtube.com/watch?v=2J2Uy3FIvMA&feature=youtube_gdata_player"]YouTube - ‪408 stroker‬‏[/ame]
 
Note i got 5000 into this motor.. Im seeing 408 with 500 to 600 hp and the same in trq did i go wrong somewhere
 
First thing that jumped out at me was the fact that the carb is too small and is probably hurting your peak hp. probably doing you fine for torque though... I'd try something in the are of 1,000 cfm. Maybe bigger.
 
How many pulls did you do? Did you do jetting and timing loops?

Are those 1-5/8 headers? I'd go 1-3/4 primaries at a minimum.

Give quickfuel a call. I bet they'll have a good recommendation. I'm betting 950.

My car made right around 340 rwhp, which is approximately 425 hp with an optimistic 20% drivetrain loss through the automatic, but I've got a factory 5.9 shortblock in mine.
You're making more torque than I am.

However, you're running the same carb and intake as my much smaller engine. Think about it like this, percentage wise, your motor is as much bigger than mine than a 360 over a 318 (318 is 88% of 360). You wouldn't want the same intake and carb on a 318 as you do on a 360....

The Thumpr cams are a gimmick to put big cam sound in street cars. You want a cam where the overriding goal is power, rather than sound.

You don't need anywhere near that exhaust duration relative to intake. What do your heads flow intake/exhaust? How much compression?

With all that torque, I'd try a single plane intake manifold. That's what I plan to do if my 408 ever gets off the ground. The Ford guys with 408s (stroker 351W) run Victor intakes on theirs and run low 10s with street cars. 4" arm makes more torque than you need single plane or no.
 
Im waiting to get the build **** to get the more detail specs...

My COMP RATIO is 10.5/1
Headers are 1-5/8
Intake is Eddy RPM Dual plane

So what cam should i have gone with.



LXguy said:
How many pulls did you do? Did you do jetting and timing loops?

Are those 1-5/8 headers? I'd go 1-3/4 primaries at a minimum.

Give quickfuel a call. I bet they'll have a good recommendation. I'm betting 950.

My car made right around 340 rwhp, which is approximately 425 hp with an optimistic 20% drivetrain loss through the automatic, but I've got a factory 5.9 shortblock in mine.
You're making more torque than I am.

However, you're running the same carb and intake as my much smaller engine. Think about it like this, percentage wise, your motor is as much bigger than mine than a 360 over a 318 (318 is 88% of 360). You wouldn't want the same intake and carb on a 318 as you do on a 360....

The Thumpr cams are a gimmick to put big cam sound in street cars. You want a cam where the overriding goal is power, rather than sound.

You don't need anywhere near that exhaust duration relative to intake. What do your heads flow intake/exhaust? How much compression?

With all that torque, I'd try a single plane intake manifold. That's what I plan to do if my 408 ever gets off the ground. The Ford guys with 408s (stroker 351W) run Victor intakes on theirs and run low 10s with street cars. 4" arm makes more torque than you need single plane or no.
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Were the Dougs headers on it on the dyno?

With stage 3 ported heads, you should be running a bigger carb. Holley 950HP would be my choice. Also, the Mutha Thumper cams are muscle car grinds made for good street power and aggressive sound, but you could do much better in power with a different cam. Comp Cam's XE295HL worked good for me (see sig for numbers). Also, the Dougs will cost you some top end power. My dyno was done with 1 3/4 Hookers, but I have Dougs on it in the car, and I know they are robbing me.

The carb change alone would probably help a bit, but if you can, you should do the cam and headers too for best gains.
 
scampmehard said:
Im waiting to get the build **** to get the more detail specs...

My COMP RATIO is 10.5/1
Headers are 1-5/8
Intake is Eddy RPM Dual plane

So what cam should i have gone with.
Click to expand...

I'm using an Eddy RPM Air Gap intake, have about the same CR, different heads, but I think yours should be comparible, and the Cam I posted above. I'm sure our internals are close to the same, but I have .030 more bore.
 
scampmehard said:
Im waiting to get the build **** to get the more detail specs...

My COMP RATIO is 10.5/1
Headers are 1-5/8
Intake is Eddy RPM Dual plane

So what cam should i have gone with.
Click to expand...

You just plain need bigger headers. Hooker Super Comps or the like. 1-5/8 are a restriction on my 360.

My first choice would be to call Cam Motion with all the motor specs and get a custom grind camshaft. Lunati and Comp do an OK job too. Its not much more money and the camshaft is the key that makes everything else work. Call em all and have the send you a recommendation, pick the one you like best.

I like Quickfuel carbs. Every time I've dynoed one, the A/F curve is pretty much laser straight. They also have a very good track record with recommendations.
 
Looks like your gonna be upwards of $6000.00 after all the upgrades that are suggested here, what are you using this for?? If it is for a street engine, is another 50 to 75 hp worth it?? guess you'd have to ask yourself that.
 
you've done a good job.....
.......Torque moves weight............
i wouldn't change anything right now, just enjoy it.
 
I agree with mrbill. If 500 ft lbs don't trip your trigger, put it on the bottle. You said the bottom end is all forged. A 150 shot should put a smile on your face. Just my thoughts...
 
The carb is a 750 jetted to a 800.
it was not the holly dbl 750 as i thought it was

I think i will stay with my headers and with my cam and just buy a 950-1000cfm carb

412 Stroker said:
Looks like your gonna be upwards of $6000.00 after all the upgrades that are suggested here, what are you using this for?? If it is for a street engine, is another 50 to 75 hp worth it?? guess you'd have to ask yourself that.
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IF I was looking for 500 or better HP, a Thumper would not be my choice. Bigger headers and carb would be on the list as well.
 
Forget that its the thumper cam.

My cam specs are duration @ .50 INT 235 EXT 249 Lift 522 if i was wanting a 500hp motor what cam specs would i want.

rumblefish360 said:
IF I was looking for 500 or better HP, a Thumper would not be my choice. Bigger headers and carb would be on the list as well.
Click to expand...
 
scampmehard said:
Forget that its the thumper cam.

My cam specs are duration @ .50 INT 235 EXT 249 Lift 522 if i was wanting a 500hp motor what cam specs would i want.
Click to expand...

Closer to 250@ .050. and over .550 lift. Who did the porting? Valve size?

Using the 295HL cam, 1.6 rockers, our RHS heads, 950HP and small headers we've made 500HP and 527TQ with no porting.
With pushrod pinch porting only, same engine but 251-260@ .050 solid FT cam we've made 521HP and 527TQ using the larger headers.

Brian
 
My machinest keeps telling me that my engine is a sweet build to be running off pump gas @ 10:1 timing @ 35* with 500lb trq. he said that the trq is whats going to get me into the high 11's low 12's.

He said he could mil the heads down a lil bit to bring me up to about 10:5 CR and advance the timing a lil more and doing this with a QFT 850cfm carb that it should put me around 500-520 hp and 500-510lb trq. The bigger headers will make a lil difference to but he would mil my heads and all that for free if i choose to do that later on down the road. Does this sound about right?
 
scampmehard said:
How much money you have into that motor and what parts and specs.
Click to expand...

Joe sherman uses the thumper cam on most of his street builds. He thought the same as most.....that it would be a noise maker but found out he could make big street able power with them. If you don't know of Joe he is pretty well respected in the racing engine business.
Here is what I have
$7k build
TTI headers
Air gap
Eddy heads
Quick fuel750
Scat assembly non forged
10.5 compression
Muthr thumper full roller
 
FWIW, I have a VERY similar engine combo. 410 stroker, 10.8:1 compresstion, stage 2 ported Edelbrocks, 750 proform carb, Comp cams XR286R (248/254 with .576/.582), Air-gap (it was this spring anyhow, now its a Victor), 1 3/4 Headman Hustlers....not sure of the exact power, but calculations say I'm making ~530hp. Runs high 10's in a 3200# Barracuda.

The carb probably isn't hurting you as much as you think. I would look at the cam. Did you degree it?

I would definitely put in a bigger cam if you're looking for big horsepower. A 950 carb would help too...I just don't think the carb alone will get you 70+ horsepower.
 
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