First drive with the updated 390, comparison to "old" 390

[chilly460]

To recap, 390 in my Merc needed to be cleaned up as years of leaks/spills/etc had it looking pretty ratty.  Stumbled on a deal for BBMs and a hydraulic roller that matched my needs so decided to update the motor while I was at it. 

Old combo:
Holley 750DP
Performer RPM (untouched)
270H (224/224 .519/.519 110LA in at 102ICA)
1 3/4" Tri Ys
9.1:1 CR
Edelbrocks with bowl and port entry cleanup and good valve job

Engine ran well, plenty of lowend, did 300rwhp with good AFR and 37* timing.  Ran "OK" but honestly for the parts involved, never felt it was that strong.  I thought maybe there was an issue with the combo, but Barry tested basically this same exact combo and made ~365hp on his dyno which jives pretty well with what mine made in the car so figured there wasn't much more to squeeze out of the combo with tuning or easy parts changes. 

New Combo:
Holley 750dp
Performer RPM (plenum entry rolled, port matched, bullnosed the plenum partition)
Survival hydraulic roller 224/230 .563/.563 110LSA 104ICA
1 3/4" Tri Ys
9.2:1 CR
BBMs with 2.09/1.65 and light seat blend

Finally got it in the car and ran it last night.  Obviously the cam is similar, but audibly and driving it gently around town, I basically can't tell a difference.  It may be a bit crisper down low at part throttle which is impressive as the car always had tons of lowend.  Also the valvetrain is quieter, can't say for certain this is cam/lifters as I spent more time setting valve geometry, but it's definitely quieter.

Punch it from a dead stop, better response, not exponentially but it now has traction problems whereas before it would dead hook.  Midrange, honestly, feels about the same.  4000rpm and up, definitely pulls harder and seems to easily pull to 6000.  Previously it would flatten over 4500, and sort of labor to 5400 or so.  It's not a wholesale change, but just pulls cleaner up top now. 

Here's the interesting point, I had both sets of heads flowed on the same bench.  I'm apprehensive to do this because the numbers are low compared to full database of what I have for similar heads and guys are going to just look at the numbers....all I care about is the difference between the two ON THIS BENCH.  It's a Superflow 600 bench, but both heads I had done were down ~15-20cfm in the .400-.600 range compared to other records.  The BBMs were done by Brent, my Edelbrocks were done by a very competent builder in PA and this wasn't extensive work on either, and plenty of comparisons for each head so I'm confident that this is just a case of that particular bench being conservative.

My  BBM Cyl1  2.09                
71   58
148   105
204   141
240   170
258   189
277   208
291   216
AVE 212.7   171.5

My Ebrocks   
79   69
148   114
180   155
218   185
248   206
255   211
257   217
197.9   165.3

The Edelbrocks are more extensively ported than the BBMs. 

Should be interesting to get it on the chassis dyno and see how the curves compare, I'm guessing about the same until 4000rpm, then the BBM combo maybe 30hp stronger at peak and carrying much better past peak.   Need to get it to the track in the Fall and see how it does, hoping low 13s but not sure I'd be confident it will get there.   

[My427stang]

Nice work Chris.

Certainly a better build and well suited for use.  You added intake air flow, head airflow, more lift, more exhaust duration, and more overlap, and rolled the cam back a little with a little more seat to seat duration.  I would expect that you will gain along the entire curve, especially mid to upper end, and the car should be a little faster because of that.

[CaptCobrajet]

With a cam like that....... streetable 220s/230s, and .563 lift, for the sake of comparison....... Figure at least .020 less lift for deflection.  Throw out the flow figures past .500, because a fairly "pointed" lobe in that range will have very little duration that will have the valve over .500 lift.  With all that said, your average intake flow is 9 cfm better, and your average exhaust is 13 cfm worse.  I would rather have the intake flow than the exhaust, but there won't be much difference in those heads, with the combo you have.  You won't get the best from BBM heads with a 2.09 intake valve.  The bowl and throat are really too big for anything less than a 2.200 valve in my opinion.  I think in a combo with a much larger cam, you would start to see the BBM stretch it out over the Edelbrock based on the info you supplied.  You certainly didn't hurt yourself on the head swap.  I think you will definitely pick up power and ET, but most of the gain is in the camshaft swap.

[blykins]

Chris, the average exhaust flow on the BBM heads is actually 155.2 cfm. 

I'm looking forward to seeing what it does on the dyno.  Try and use the same dyno as last time to eliminate any variables.

I will agree with Blair here....I think the hydraulic roller camshaft will be responsible for a good bit of the power bump.  I know that the cam is one of Barry's, but I recently ground a hydraulic roller for a forum member to replace a 294S.  With less duration and similar lift, it made almost 30 hp more with no other changes.  I would expect similar results here, especially with the extra exhaust duration.

I will also say that I think Barry's lower duration cams use a little more aggressive lobes than what I use, which means that the .200" duration will be relatively higher and the advertised durations will be relatively lower.  The higher .200" duration will actually hold the valve open longer, and depending on the lobe shape itself, may snap it open, hold it open, then snap it shut.  You will see some lift loss due to pushrod deflection and valvetrain geometry, but I think the overall lift at the valve will be significant.  You may also see a power increase because of a DCR increase.

The bowl and throat on a BBM are "by the rule" larger than what's optimal for a 2.090" valve, but I have used smaller intake valves several times when the bore size is fairly small.   I know that you bought these second-hand and I can't remember the specs for the engine that they were originally intended for, so that may have been a deciding factor.   You did the right thing and had both sets of heads flowed on the same bench.   I particularly like the flow bump from .300-.500" lift.  A 22-24 cfm bump there is a tremendous help. 

Let us know what the dyno says.

[chilly460]

Thanks all for the information, good stuff to chew on.  I understood going in that this was an incremental step at best, as I said I got a nice deal on the BBM/Cam and this was a "while your at it" deal to upgrade a bit while I had the engine out for some cleanup.  I believe the heads/cam were spec'd for an "interim" 390 while the guy was building a 445/462 but the details are foggy. 

The BBMs are scheduled to go on the 462 I'm gathering parts for, so there are longer range plans that will include getting the heads opened up for the 2.20".  I've been reading a bit about throat sizes, pinch points, minimum CSA and the like just trying to get educated, my guess is that it's not as crucial on a mild 390 like this but on a 6000rpm 462 it will matter.  I was hoping the better chamber in the BBMs would help a bit too.  Also used this as an opportunity to learn how to set pushrod length, degree a cam, port match (rather than gasket match), use a dial bore gauge before I do these things on the 462.  I've slapped together parts before but wanted to get a wee bit more into "building". 

Brent, I can hit the same chassis dyno to get somewhat of a back to back comparison.  He's usually fairly backed up but I'll see when I can get on the rollers.

[Barry_R]

I'm gonna place a bet that it runs better than the "butt-o-meter" is telling you....

[chilly460]

Well we will see, dyno appt setup for Aug 7th. 

[Barry_R]

 

[Drew Pojedinec]

Kinda hard to tell on the street when the power is higher rpm.
Least with my car, if I get real serious about it, traction makes it not matter so much.

[chilly460]

For research purposes only 

Needs more go juice

https://youtu.be/Fop57nAYa_4

[blykins]

Now what has that poor seat ever done to you?

[chilly460]

LOL, couldn't get the phone mounted to the quarter window without blocking view of the tach or oil pressure gauge, without putting the seat forward. 

[mbrunson427]

Shoot, sounds like it's running pretty hard to me! From the video, seems the same as our warmed over 390 Mustang, but you're doing it in a Galaxie.

[Drew Pojedinec]

I use 14 year olds as cameramen.  Works great and is easier on the seats

https://www.youtube.com/watch?v=v13_72XREP0&feature=youtu.be

[Stangman]

Sounds great

[Bolted to Floor]

Thanks for the ride.   

[My427stang]

Sounds GREAT for a 390 in a big car...wait until we get you bit by the 4.25 stroker bug

[chilly460]

Thanks for the feedback guys.  On reflection I think I was expecting a bit much from this.  Maybe the best testament to the combo is it never feels like it's in a "big" car.  I guess I've been driving trucks and other heavy vehicles so long, I don't even think of the Merc as being "big".  Anyway, light throttle, cruise, rolling throttle, WOT...it never feels like it's hooked to a 4400lb combo.  2000rpm in O/D, it pulls great, and now with the new combo it feels pretty good over 4500 where it used to flatten out.  Will get it on dyno and try to get it to the track to quantify things. 


Lol, already there, Ross.  I have a 428 block I bought from Jay, Blue Thunder 2x4, carbs on the way from Drew, and picked up some Mahle pistons for a 4.16 x 4.25 stroker I found at Carlisle for $150....all plans are in place to put a pretty nice 462" together.   Deciding if I want to run a set of Medium Risers I have on the shelf (after port work) or go with a set of TFS. 

[turbohunter]

Looks like fun. And yeah, sounds great. Congrats.

[Drew Pojedinec]

I have a 428 block I bought from Jay, Blue Thunder 2x4, carbs on the way from Drew

Two boxes should be knockin on your door tomorrow

IMG_0792 by Drew Pojedinec, on Flickr

Adding 70ci is going to make this feel like a different animal for sure.

[chilly460]

The Ass-o-meter calibration was pretty good.  I thought it was around 30hp better, it was 34hp stronger this time around with best gains over 4500, but better through the whole curve, smoother curve up top, made 334rwhp at 5500 and 386ftlbs at 3400.  Nice tow truck motor. 

 Overall a good day, started with 32* and it was up 10hp at 34* then down 5hp at 36*.  Not apples to apples, being run on a different day, 99* in the shop and water was at 205* for the pulls so it’ll like cool weather.  Just a tiny bit fat in the midrange but perfect otherwise so I’ll leave jets as is, they’ll be perfect in cooler weather

https://youtu.be/lwjz56WuBe0

https://youtu.be/YVq0iSd8Pmc

[blykins]

Pretty healthy bump for no increase in peak horsepower RPM.

[chilly460]

Yep, after thinking on it a bit, happy to pick up a good chunk of power along with actually helping low rpm power as well

[gdaddy01]

very nice , I will have to save this one , thanks for sharing .   

[Barry_R]

A 10-12 percent gain with no negative sounds about perfect for this type of deal.  Never tested that particular swap, but based on other ones I have compared I imagine that the cam is probably 50% of the gain here.  I normally try & spec hydraulic rollers to peak somewhere between 5500 and 6000 depending on the build and vehicle (weight, power requirements, compression, O.D. trans is a big one because of cruise RPM...).  That particular cam has become a "go to" for use in big cars and you have the reason "why" right there - no downside at lower RPM and still works well further up the curve.

[chilly460]

Barry, I'm definitely happy with the cam.  As stated, it's helped the lowend, and helped it pull 4500+ and flattened the curve up top.  It pulls O/D cleanly at 1600rpm, and is "on the cam" at 2000rpm, can easily roll into the throttle at 60mph cruise and zip up to 80mph without a downshift.  In the video I took of the Dynojet display, you can see he ran it to 6000, it would never get there with the old combo, it ran clean but was flat over 5200rpm or so and would labor over 5500, absolutely no reason to run it up beyond there previously. 

 

[BigBlueIron]

Chilly,

Having never been on a wheel dyno give me an idea of what you have for a trans and what gear the pull is made in. I assume close 1:1 as possible.

And I'm curious how gear ratio and tire size plays into the outcome.

[chilly460]

TKO 500 trans in 4th gear, which is 1:1, 4.10 rear, 28" tire. 

I assume they run it in 1:1 to reduce variables caused by the trans gear adding additional leverage, and it bypasses the cluster gear so .  As for rear gear, I've read up a bit on it and there's a rule of thumb that for every change of 1.00 in the rear ratio - 15-20hp I've seen thrown around.  No idea if it's true, but did find quite a few references to the lower gears being down on power so I'm guessing there's some credence to it.  Whether it's due to increased friction or with how it calculates inertia into power figures, nobody seems to really know. 

My thoughts are a lot of the myths/guesses/rules of thumb from chassis dynos stem from guys trying to justify why their car didn't pull as much HP as they thought it would.  God help the high stall convertor auto guys, their chassis dyno numbers are all over the place. 

In the end, any attempt to calculate actual flywheel HP from a chassis dyno number usually is fruitless.  Always boils down to what it will do at the track.  I had a '93 Lightning, basically stock with a supercharger pushing 7psi with a tired engine that pulled 300rwhp but ran 13.01 at 103mph at the track and surprised me.