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Dyno numbers are in!

evilmopar

evilmopar

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Hey guys! I just finished my 440/500 build and ran it on the dyno.. But i was a bit dissapointed, it stopped making power to early, sure got some nice tq numbers but the rpm are to low, i was hoping it to be happy for atleast 1000rpm more, but it died off. So i need your experts to give me some clues of what could be wrong with my build.. Here are my specs to start with...

.055 over 440 with 440source 4,15 stroker kit
11.6 CR
Untouched TF 240 heads
Brawler race 950 cfm 4150 carb
TF Trackheat intake
Crane ductile iron 1.6 rockers
PAC 1.46" springs. 120lbs seatpressure @1.9" Installheight, 394lbs Open
Howards Solid flat-tappet .657/.661 (with 1.6) 260/264 @.050, LSA 108, ICA 104
MSD Probillet dissy 32degrees full ignition.. Tried 36 but made more power with less


And here are my dyno sheets
FFF75EF5-E653-4484-B5F3-5E152914FDF4.jpg
IMG_0156.jpg
 
That looks pretty close to what the 446 cu in dyno mule made just at a lower rpm. My guess is bigger ports and bigger roller cam to extend the Rpm with a 500.
 
4406bbl said:
That looks pretty close to what the 446 cu in dyno mule made just at a lower rpm. My guess is bigger ports and bigger roller cam to extend the Rpm with a 500.
Click to expand...

I just ordered a new set of springs, My thought was maybe start of valvefloat, Howards recommend a spring that has 140 seat pressure and 420lbs springrate.
 
4406bbl said:
That could be it too.
Click to expand...

I haven´t put the engine in the car yet, and the springs i ordered have the same installheight as the ones that are in, just hoping the retainers i ordered don´t change that, then the swap is a quick fix, atleast to be on the safe side and don´t break a piston or valve salad. Porting heads would be a to big job before race season, even here in sweden (snowing today)
 
Probably intake design and not springs. Check pressure on them before you pull the old ones.
 
Nice numbers!!

I think it’s a bit optimistic to be looking for the motor to peak at 1000rpm higher than where you’re at now.
Std port windows and 500” don’t usually peak really high.
The springs on the heads are def a little light for the cam/rocker combo, so I wouldn’t be surprised to see the peak get shifted a little higher with the new springs...... maybe closer to 6K.

The tq is good, and at a sufficiently high rpm, that if it can hang on a little stronger after peak....... you’ll see that peak hp happen a little higher up.

It would have been nice if there was an air turbine being used...... then you could monitor the air flow going into the motor.
When the springs start losing control, it shows up in the air flow readings.

I’m wondering why there are no bsfc numbers...... running efi perhaps(and bypassing the dyno fuel system)?

Did you make any pulls to a higher rpm to see what happened with the curve?
 
Last edited:
BanginGears said:
Probably intake design and not springs. Check pressure on them before you pull the old ones.
Click to expand...
Recomended springs are 142 seat and 420 open. Mine are 120 and 394 (trickflow rated them for .700 lift according to their catalog, thats why i didn't change them, but their specs are wrong!).. According to the tuner and a engine builder here they pull mopar strokers (500,505 and 512) higher and same power numbers on untouched chinese heads.... And i trust those guys the tuner is very well known here in sweden. Changing springs will atleast make me sleep better knowing i won´t break parts due to low spring rate lol
 
PRHeads said:
Nice numbers!!

I think it’s a bit optimistic to be looking for the motor to peak at 1000rpm higher than where you’re at now.
Std port windows and 500” don’t usually peak really high.
The springs on the heads are def a little light for the cam/rocker combo, so I wouldn’t be surprised to see the peak get shifted a little higher with the new springs...... maybe closer to 6K.

The tq is good, and at a sufficiently high rpm, that if it can hang on a little stronger after peak....... you’ll see that peak hp happen a little higher up.

It would have been nice if there was an air turbine being used...... then you could monitor the air flow going into the motor.
When the springs start losing control, it shows up in the air flow readings.

I’m wondering why there are no bsfc numbers...... running efi perhaps(and bypassing the dyno fuel system)?

Did you make any pulls to a higher rpm to see what happened with the curve?
Click to expand...

Bsfc was broken so we just meassured afr and diff pressures above and under carb. I hope to get some more rpm to be able shift a bit later and be able to run the full 1/4 lol . The cam is rated 3K-7400 so i thought peaking at 5300 is a bit early, No we didn´t pull it higher, don´t know why but i ask the dyno guy to run it to 6K to see what happens.

I got new springs today 145 seat and 457 open, 425 rated. Those are the closesed to Howards recomendation i coud get with the same installheight i have ´right now and that i could get here in sweden. Maybe i should aim for a decent port job after the summer, get someone to port the hell out of them, going full maxwedge size or as big as possible (someone who has the knowledge need to do it). Guess the 270 and the 240 heads are the same casting just a different cnc-program :drinks:
 
The 1.46 diameter spring that comes on the TF Mopar heads is a PAC-1903.
I just took a set off some TF SB heads.
The were set up at a nominal 1.900 installed height.

The specs from PAC are [email protected], and [email protected](.650 lift).
On my spring tester....... that’s also what I get.

For a fast rate .904 SFT cam with 1.6 rockers, I’d be shooting for more like 150-160 closed, 410-430 open...... if I was looking for stability up into the 6500rpm range.

Going by the specs in the Howard’s catalog, the 98632 spring should end up at [email protected], and [email protected].
 
Last edited:
PRHeads said:
The 1.46 diameter spring that comes on the TF Mopar heads is a PAC-1903.
I just took a set off some TF SB heads.
The were set up at a nominal 1.900 installed height.

The specs from PAC are [email protected], and [email protected](.650 lift).
On my spring tester....... that’s also what I get.

For a fast rate .904 SFT cam with 1.6 rockers, I’d be shooting for more like 150-160 closed, 410-430 open...... if I was looking for stability up into the 6500rpm range.

Going by the specs in the Howard’s catalog, the 98632 spring should end up at [email protected], and [email protected].
Click to expand...


I just got the comp 953 i hope they will be enough for my setup. It would be nice to turn a bit higher. Just read about a 512 with OOTB 240 (changed springs) that ran 9.89 and turned 6800 across the stripe (moparats.com).

The 953 is 148 closed and 456 open.
 
Last edited:
Everyone has their own way of testing, but on a build like yours....... the only way I would have only pulled to 5500 was if there was an obvious problem being encountered by going higher.

Here is a 505, Stage 1 RPM heads, XS290S cam, 1.5 RR, 6bbl.
About the same TQ as yours, but doesn’t carry it as well with the dual plane and lesser flowing heads.
Still hung on pretty good to 6K.

7F64783A-811C-4920-923B-50291CB6E79A.png

What sized headers were you using on the dyno?
Too small and it’ll def kill off some top end.
 
evilmopar said:
I just got the comp 953 i hope they will be enough for my setup. It would be nice to turn a bit higher. Just read about a 512 with OOTB 240 (changed springs) that ran 9.89 and turned 6800 across the stripe (moparats.com).

The 953 is 148 closed and 456 open.
Click to expand...


You're really not going to see much of a gain in ET and mph IMHO.
You're limited to what you have in ci , heads and cam and compression.
 
Your peak torque is right where my 512 runs best. Similar build but with a M1 intake and 4500.

To the original question if it was mine I'd run a 4500 carb. My set up really woke up after switching from the 950, 4150 Holley to a 4500. Also with the heads you have I'm confident that you will pull strong to at least 6300. I'm running basically stock Edelbrock Performer heads( way inferior to the TF) on my 512. I shift at 5500(most of my racing is 1/8th mile but in 1/4 I'm still pulling strong at 5900 when I cross the stripe).

But if you need to shift your rpm up some I have found the with max wedge ports you can move the power band up about 500 rpm.
 
PRHeads said:
Everyone has their own way of testing, but on a build like yours....... the only way I would have only pulled to 5500 was if there was an obvious problem being encountered by going higher.

Here is a 505, Stage 1 RPM heads, XS290S cam, 1.5 RR, 6bbl.
About the same TQ as yours, but doesn’t carry it as well with the dual plane and lesser flowing heads.
Still hung on pretty good to 6K.

View attachment 1106828

What sized headers were you using on the dyno?
Too small and it’ll def kill off some top end.
Click to expand...

The reason why we pulled from 3000-5500 is because the engine is brand new (minus heads and block) so we brokein the cam and rings and when we started making pulls he set the load at 3-55 to start with, but when the engine didn´t make power above 5300 there was no point in increasing rpm (i still wanted to pull it 6K) It was a 1 7/8 dyno headers, i run 2" fenderwells in the car.
 
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