401 sbc ready for the Dyno

[HQM383]

I'm wondering how accurate the hp/torque readings are.

Time and the track will tell. The dyno sessions have served their purpose. I won't lose any sleep if the real hp and tq numbers are 10 - 15 less than the results show as that's all I expected anyway.

What do you feel, if any, will be the losses once it's in the car? Headers and exhaust will most likely take something out of the dyno numbers. And accessory drives: P/S, alternator, water pump, etc.

Only an alternator to drive and the headers used on the dyno are my in-car headers. 3” twin exhaust with X-pipe and one straight through muffler each bank.

[KnightEngines]

Just a small pointer, motor should be cooled off between pulls & water & oil temps kept consistent for each pull.
A 20 deg change in oil temp can change power by up to 5hp.
So if you're looking for small changes its best to keep oil temp at the start of each pull within 5 deg of the baseline.

[HQM383]

Just a small pointer, motor should be cooled off between pulls & water & oil temps kept consistent for each pull.
A 20 deg change in oil temp can change power by up to 5hp.
So if you're looking for small changes its best to keep oil temp at the start of each pull within 5 deg of the baseline.

Thanks Tony, noted. Good information to bring next time when this combo steps it up with bigger heads. It was a basic introduction to engine dynos that wasn't overwhelming with data and procedure. The finer points I
appreciate you mentioning will enhance the next session.

[skinny z]

Time and the track will tell. The dyno sessions have served their purpose. I won't lose any sleep if the real hp and tq numbers are 10 - 15 less than the results show as that's all I expected anyway.

What do you feel, if any, will be the losses once it's in the car? Headers and exhaust will most likely take something out of the dyno numbers. And accessory drives: P/S, alternator, water pump, etc.

Only an alternator to drive and the headers used on the dyno are my in-car headers. 3” twin exhaust with X-pipe and one straight through muffler each bank.

Obviously your focus has been on the induction top side. I appreciate your posting results and hope to use it to good effect once I'm experimenting the same way.
That said, have you worked on any header math? Collect length if open and overall exhaust length to the tailpipes? Or the muffler spec considering whether they react as an open pipe (simulating atmosphere) or an extension of the overall system?

Among my hobbyist racing friends and myself, I've seen how the exhaust in and of itself tends to be a performance killer despite encouraging results from a dyno session. Free flowing is one thing. It seems tuned is something else altogether (right PipeMax Larry?).

Even one of my earlier measly pile of parts gained 1-1/2 MPH in the 1/8 by simply opening the exhaust before the single muffler (possibly the worst exhaust system designed from a performance standpoint).

I only bring this up as once I'm back at the track, I'm hoping to incorporate collector cutouts to simulate the premium result from open headers. Tuned accordingly of course.

[HQM383]

Obviously your focus has been on the induction top side. I appreciate your posting results and hope to use it to good effect once I'm experimenting the same way.
That said, have you worked on any header math? Collect length if open and overall exhaust length to the tailpipes? Or the muffler spec considering whether they react as an open pipe (simulating atmosphere) or an extension of the overall system?

Among my hobbyist racing friends and myself, I've seen how the exhaust in and of itself tends to be a performance killer despite encouraging results from a dyno session. Free flowing is one thing. It seems tuned is something else altogether (right PipeMax Larry?).

Thanks skinny.

Not yet. Some work will have to be done to see if the exhaust system I listed will cut the mustard performance wise. At the moment it's at practicality stage of planning.

As mentioned previously I became aware that if heads are limited in flow capability (2.0" mcsa and 255cfm @ .500" and 257cfm .600") then as much inert gas as possible needs to evacuate the combustion chamber to make what's coming in the combustion chamber most efficient and effective. In this respect a lot of homework was done on the exhaust side of the camshaft and valve train. I may be way off the mark and haven't spent a whole lot of time thinking on it but maybe no more gains are to be had with carbs or spacers because its doing just that. But of course, as you rightly raise it doesn't end at the header extension when in the car so more is to be done to work within the small box of street legal.

[HQM383]

Plugs #1, #5 and #2.

[tuffxf]

What’s on the porcelain of the 1st pic in the 12 o’clock position, picture isn’t real clear

Cheers

[KnightEngines]

It may like 1-2 deg less timing, timing marks on 1&5 are a bit low, 2 looks bang on.
Heat range looks good.

[HQM383]

What’s on the porcelain of the 1st pic in the 12 o’clock position, picture isn’t real clear

Cheers

Collected a dab of silver antiseize on the way out.

[HQM383]

It may like 1-2 deg less timing, timing marks on 1&5 are a bit low, 2 looks bang on.
Heat range looks good.

NGK 7's.

Pulled them this afternoon when I got there. Would have had a bit of idling on them yesterday before shut-down. But a bit of jetting will come out. Main purpose pulling them today was making sure no anomalies. Except the various timing witnesses marks all the same. Timing was at around 34°. Checked lash and all good and ran over it and snugged up some bolts now its done half a dozen hot/cold cycles. All that was done today after the health check was to connect and check how the vac advance goes on the ICE box. Tomorrow's plan is revisit timing. I want to try adding some initial for cleaner idle then work through box set curves again. Thanks again for your feedback Tony.

[HQM383]

I don’t think any more power will be squeezed out of this small head 401 sbc. So time for a bit of fun and revisit the guesstimates.

I’m calling it 568hp @ 6500rpm and 532ft/4900rpm from a run with 975cfm carb that wasn’t influenced by multiple runs (the 571hp/538ft/lb run)

Ok as a Ford man i'll go..........

525hp @5900rpm

520tq @4500rpm

Sorry bob, maybe lack of sbc faith clouded your estimate

520 TQ 590 HP
Hope you're taking some exhaust rockers (1.6 or 1.65 ) to see if it adds above the HP peak and maybe doesn't hurt elsewhere.

Loved the faith you had in the sbc Tom, but no cigar

I've got a smaller cam, bigger heads and I made 540 hp and 525 tq so I'll say 250 hp and 300 tq...but the dyno probably wont register that low lol, so 550hp and 525tq

Not too shabby Steve, good estimate but still on the low side.

Ill guess 580HP@6200 / 530Tq@5100
Really interested to see the results.
All the best.

Good stuff Xanadu. Within single digits now!

As for HP and TQ?
I like this guess...
"560hp @ 6100rpm and 530ft/lb @ 5000rpm".

Good luck.

skinny, I feel I’m experiencing deja vu. But well done on the close estimate, fellow hobbyist!

I think 1.30 - 1.35 ft lbs per cube is achievable and I agree peak torque around 5000rpm.
I also think 560hp......

With torque equating to 1.33ft/lb per cube and your hp guess your close to a podium finish Steve!

With the Twisted wedge heads you may be 520 hp/500 torque range......

Every right to doubt the almost 30 year old technology head, but this time they “punched above their weight”

Very close to mine. You have 20 degrees more on the cam but smaller heads and you have an electric water pump so I'm gonna guess it's close to a push: 562hp . 534tq. I don't have a sim so this will let me see how mine compares.

We have our closest to the pin winner! Great estimate DCal
Good luck with your build!

[54chevkiwi]

I'm convinced now the 10° set up puts the rotor to the clockwise side of the cap post. In the previous pic one of the alignment marks is over the O and N on the Progression sticker. Cap post is anti clockwise to that black mark in below pic. Correct 10° set up should be good phasing as circuitry is telling it to fire 10° BTDC as the rotor is almost past the post. My yellow line is a bit wonky but you see what I mean.

Can I get you to clarify this so I get it please? I think I'm following....

The distributor has those notches which you're meant to install it at which puts it at 10* btdc on install and initial fire up before programming?
and in the second pic, you're showing that those notches are out of alignment with the poles on the cap? So, to correct this, you're changing the position of the contraption so the rotor is installed in line with the post to correct the phasing issue at 10* btdc?

[54chevkiwi]

Can you clarify for me also, youre just using the 6al box to amplify the spark, you're not abandoning the progression thing and using it to program timing?

[HQM383]

I'm convinced now the 10° set up puts the rotor to the clockwise side of the cap post. In the previous pic one of the alignment marks is over the O and N on the Progression sticker. Cap post is anti clockwise to that black mark in below pic. Correct 10° set up should be good phasing as circuitry is telling it to fire 10° BTDC as the rotor is almost past the post. My yellow line is a bit wonky but you see what I mean.

Can I get you to clarify this so I get it please? I think I'm following....

The distributor has those notches which you're meant to install it at which puts it at 10* btdc on install and initial fire up before programming?
and in the second pic, you're showing that those notches are out of alignment with the poles on the cap? So, to correct this, you're changing the position of the contraption so the rotor is installed in line with the post to correct the phasing issue at 10* btdc?

What appears to be out of alignment is correct. At low advance the rotor and terminal have to be to the far side of direction of rotation so as the distributor advances the timing it is arcing earlier and closer to the center of the flat plug terminal inside the cap. If the rotor began lined up central with the terminal as it advances it may want to send the spark before it is within proximity. What Tom was referring to earlier is with a small diameter cap the terminal post are closer and out of phase the spark may find the previous terminal in direction of rotation instead of the one it should be firing on with high Ignition advance.

[bob460]

I don’t think any more power will be squeezed out of this small head 401 sbc. So time for a bit of fun and revisit the guesstimates.

I’m calling it 568hp @ 6500rpm and 532ft/4900rpm from a run with 975cfm carb that wasn’t influenced by multiple runs (the 571hp/538ft/lb run)

Ok as a Ford man i'll go..........

525hp @5900rpm

520tq @4500rpm

Sorry bob, maybe lack of sbc faith clouded your estimate

Or maybe "happy dyno" ............Just kidding. I didn't even know they had a dyno.

Now you need to back it up at the track.

How much the HQ weigh?

Good job all round