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NOpe, I"m on 93 octane with a shot of boostane for homemade 95 octane. Although, I'm wanting to test a theory. I think these heads might actually let me tolerate more compression even without the boostane
Thanks! I figure the curve will be a table top, but it depends on how you define "low end". SOTP, this thing really doesn't come into it's own until about 3K, and then it hits like nitrous. One thing I will say, I was having some issues with off idle stumbling, and that's gone, so now it whips when you stab the throttle.
That would be cool. I'm expecting more of a triple-hump type of torque curve. I tend to see that on larger cam / long runner combos. Even on the LS1's with a fast 102 and a big cam, I tend to see multi-hump torque curves
Tony's heads do have a very efficient combustion chamber design which will help.
Ok, so here it is. I’m truly sorry it took so long and to keep y’all in suspense. I held off posting until I had enough data to say for sure what the car is actually doing and make sure that it is accurately characterized. Without further ado, let’s dive in!
***The short version is the final numbers are 692/551 on a jet, radials, manual trans, 9-inch rear, 4.30 gear, and an open X pipe.*** I cannot begin to describe how happy I am, nor how surprised the guys at the dyno shop were at this thing. All the details for how we got there are below:
Here is the before picture -- the car made 577.96/489.04 on 11/25/19 running full exhaust and 28” radials
On 8/27/2020 on the same dyno RUNNING BIAS PLY SLICKS and full exhaust, it made a baseline of 627 with only 20 degrees timing and 11.5 AFR. I let up at 6K, because there was no point. I had loaded a conservative tune for KR avoidance. After lots of pulls, it made a best of 651/548. However, on that dyno, we were having issues with the RPM signal, so the only clean graph I got shows 645.78/532.47. Now, I’d like to put that number into perspective. The new Mamo Motorsports 265 set up gained 75 HP and 50 lbs torque over a previous Lingenfelter ported heads, solid roller cam set up. **94/62 improvement when you factor in the change in tires from radials to slicks (more on that below).**
The operator, owner, and several employees were seriously impressed with this thing. The only NA motor they had higher than this on their dyno was a high compression full racealcohol burning tall deck 447, mast top end, CID intake, 4500 throttle that made 671 open headers and on radials through a powerglide (lightweight efficient two speed trans), and that motor went on to run 5.5 in the eighth at Orangeburg. While talking about it, the dyno operator told me straight up that this dyno is known to be on the conservative side. He said they had never seen a full exhaust car make over 600 NA on their dyno. I mean this number was so big on their dyno, guys were taking pictures of the car and the dyno graphs. One of the employees then looked at my tires and said, “Well, hell, put radials on and that’s 30 more HP right there!”
So, I left there really happy and quite stoked for the rest of the evening, but there were a few things that continued to course through my mind:
1. The car hit 6300 and the HP curve flatlined a bit but it pulled strong straight across to 7300. Pull after pull after pull 22 to 26 degrees timing, and 11.5 to 13.0 AFR. 651-650-651-649-651. The dyno operator and I reasoned that this could be the exhaust system, because, as said above, they never see those kinds of numbers on full exhaust.
2. The only comparison engine they had that made more power than mine ran so fast in the eighth, I felt like their comment that the dyno is overly conservative was potentially legit.
3. I dyno’d on slicks, because that’s what I drive on now out of necessity, since I rather enjoy not going sideways on the interstate when passing trucks. Several employees said it would pull much higher on radials and that’s pretty much an accepted truth anyway. More on that later
4. Plug number 3 is badly fouling. There is a severe oil leak into cylinder 3, and it’s bad enough to oil foul the plug in one pull. Not sure how that’s affecting the result. I need to pull the VC and intake to see what’s going on. But, before doing that….
I am not one to settle for a bunch of ricer math. So, today (8/28), I set out to answer a few questions:
A. Exactly how low does the dyno read? Easy test – simply go to a dyno recommended by the dyno operator as having more typical results.
B. How much is a dual 3” exhaust actually holding it back? Easy test – drop the intermediate pipes and dyno “open X”
C. How much of a difference will radials actually make? Easy test – swap tires
So, I did exactly those three things. Now, the exhaust is such a PITA, and I don’t want to pay for dyno time by the hour dropping exhaust, so I dropped it at home. Also, I didn’t want to drive dyno to dyno back and forth, so I just went to the nearby alternate dyno the operator suggested. I did not redyno on yesterday’s since I could get my answers either way at this point. New dyno was also a dynojet. Only difference was the diameter of the rollers. 24” vs 48”. Thirdly, I rented a set of 28” radials on 16” rims to comparative test.
Now, the fun part
*Test 1. Testing the stinginess of the first dyno AND open X pipe, car made 673.52/551.67. Peaked at 6700 and 5100 rpm. This time, however, it continued building power through 6500 or so (vs 6300 before), leveled off, and carried until I let up. But what’s more interesting is it raised the entire torque curve. Same shape, just 15-20 lbs higher all the way across. What that does to the math is move the power peak out a bit. Kind of neat really. Now, I’m honestly not sure if the dyno was worth 20 and the exhaust was worth 2 or the exhaust was worth 20 and the dyno was worth 2 or anything in between. But both changes combined, gained about 22 from the best run I had from yesterday (8/27).
*Test 2. Testing the slicks vs radials, I knew I would not get the highly touted 30 HP gain, lol. I did happily gain 19 and change. Car made 692.23/551.90. Peaked at 6900/5400 rpm. This time it crested and fell off more like a normal curve will do. It’s really kind of cool, because you can see the torque curves diverge. The bias ply have more torque down low, and the radials have more torque up top. It looks almost like a slight cam adjustment! But it makes total sense. Stiffer side wall, and possibly a slight diameter effect from the tires. Also sort of shows why bias play help you launch and radials tend to trap higher, all things being equal.
In the pic below, the blue and green lines are open X on slicks. The red and pink lines are on radials. No timing or fueling changes were made for those two pulls, as I was only testing for dyno/exhaust and tire effect. So, there it is. 692/551 through a T56, 9-inch, 4.30 gear, open X pipe, and borrowed radials on a dynojet. All with replacing #3 plug on every pull due to severe oil-fouling! Yeah, I went through some plugs
No timing or fueling changes were made for those two pulls, as I was only testing for dyno/exhaust and tire effect. So, there it is. 692/551 but still with #3 badly oil fouled!
Only down side, and I hate to even think it, but likely the head is going to end up having to come back off again to fix it for good and then be able to just enjoy the car. Again, sorry for the delay, but hopefully, it was worth the wait! J
If it makes 700rwhp that is very stout indeed.
800hp at the crank NA with a plastic intake is bananas.
It really is. Hard to say what it is at the crank. In some ways, my driveline is pretty efficient (T56, CF driveshaft, light clutch) and in other ways it is very inefficient (9-inch, 4.30, heavy rear brakes). I suspect the intake is about tapped out, and if I wanted to do much more with it, i'd have to cut the snout off and epoxy in a flange for a 112mm or even 125mm TB.
Originally Posted by spanks13
Those are some serious acceleration numbers. Sounds exciting! How high have you reved it out to so far?
When's the dyno appointment??
It moves out. I revved it out to 7200 on the street and 7600 on the dyno. On the street I just ran out of road. it's really hard to explain this thing over the internet. Spent the last two days on the dyno. I was trying to balance getting good info and not paying for dyno time while updating the internet. Really crammed a lot into two days.
Congrats Darth! GH is absolutely amazing. Thanks for all your hard work on this project. I thought slicks to radials would be worth a little more on the dyno. That's good to know.
Congratulations Darth.
Those numbers are very stout.
Comparing it to Josh B dyno sheet you were only 8hp down with a much smaller camshaft and shorter stroke.
I'm seriously impressed.
I'm curious to see how it does once you fix that oil issue fouling the spark plug.
i think there is still a bit more left in it.
I bet that thing would pull like it wants to kill you.
On another note, I remember you telling me that you are wanting to shift at about 7800rpm or so correct?
It looks like the power is falling off pretty hard at 7300rpm.
Personally for me I would leave it as is but for your goals is it what you are wanting?
Congratulations Darth.
Those numbers are very stout.
Comparing it to Josh B dyno sheet you were only 8hp down with a much smaller camshaft and shorter stroke.
I'm seriously impressed.
I'm curious to see how it does once you fix that oil issue fouling the spark plug.
i think there is still a bit more left in it.
I bet that thing would pull like it wants to kill you.
On another note, I remember you telling me that you are wanting to shift at about 7800rpm or so correct?
It looks like the power is falling off pretty hard at 7300rpm.
Personally for me I would leave it as is but for your goals is it what you are wanting?
Bort,
You kill me sometimes....falling off pretty hard at 7300?? What graph are you looking at?
At 7600 its barely off 10 HP from its 6900 ish peak.....this engine would need to be shifted 7800 - 8K to ride the fattest part of the power curve in every gear (the highest average power from shift point to the next gear RPM drop)
For a long runner intake design (which boosts power through the low and middle part of the curve), having to feed 440 hungry inches well north of 7000 RPM, the "plastic fantastic" ported MSD is performing it's job admirably here.
Peak power is almost flat from 7K to 7600 where the last and best dyno with radial tires installed punched the biggest number yet (692 RWHP / 552 RWTQ). I could tell you from all the time I have spent at Westech that slicks kill you on the chassis dyno.....on the round rollers, they deform too much at high RPM and kill power.
Also guys, this is in an FBody (which never dyno's quite as good as a Vette due to the Vette's ideal exhaust layout and more efficient driveline) ......and Jacob's car is handicapped in a big way with a Ford 9" rear, 35 spline axles, and a 4:30 gear ratio. Its is the anti dyno queen!
Same engine in a C6Z (even with the beefier ring and pinion in that car compared to regular C6) would be up 15 - 20 RWHP easily.
Darth's 4:30 ring and pinion ratio vs a C6Z's 3:42 ratio really hurts output alot and the 9" Ford's rear massive component weight and low un-optimized pinion location kill it in efficiency even further reducing net power at the wheels.
In fact Im confident this engine is 710+ RWHP in a C6Z with the same light clutch and manual 6 speed trans.....which puts it right around 800 flywheel a number that most of Darth's metrics also support.
Jacob a big congrats....it's been a long road but one well worth traveling. Hopefully we can sort out the #3 choo-choo train cylinder and get you back on the road running clean for further tweaking of this impressive effort.
Its really huffing smoke (saw the vid)....I have to think eliminating that problem could be the magic that might help this baby clear that 700 number which in this car is one hell of an achievement. Its reducing our octane quality at the very least. Who knows....it might be worth nothing but it might be worth a little. We shall see
Looking forward to the final tweaks and the nickels and dimes I know your going to be chasing.....this thing should run some serious MPH at the track also and you should have it sorted out by the time the cooler months arrive which is ideal for track testing.
Hats off to all involved.....Chevelle (Scott) that's aimed right at you.....you played a major role here.
A bit of a bumpy ride but really exciting results that make it all worthwhile with a few question marks still lingering that might help it look even better when the smoke clears
Sorry Tony I was looking at the top dyno sheet.
You are correct with the bottom sheet.
All flat to 7600rpm.
Guy's please don't give me any grief about it.
That is such a good torque and power curve though.
I look forward to the tweaks and fixes.
It would also be awesome if Darth did an acceleration run for us to see the fury unleashed.
Awesome result and power. I imagine a wot pull through the gears it eats the road so fast you don't even realize what just happened kind of fast.
One thing.. shouldn't this cubic inch and power level be using 3.5" collectors (regardless of 1 7/8 or 2" primaries). I'm sure there must be some gain to be had.
Some of the shelf 1 7/8 headers over in my country which are made for the LS1-2 powered Holdens, they have 3.5" collectors instead of the typical f-body 3" collectors... and i've seen those headers work really well even on much milder builds than this one. I could be wrong, but i think twin 3" is restrictive at near 800 fwhp level, even if running open collectors, but especially if running into a dual 3" Y or Xpipe.. i really think dual 3.5" can benefit out of the primary tubes on a build like this.. and i know it can fit under an f-body no problems, at least the collectors and Y pipe.
After a few thousand miles ,it would likely hit 700aa well. Completely fresh motor here.
another point, jacob is using the smaller vacuum pump, the pro size would be worth a few hp I'd think since its probably not pulling much over 10" but im speculating.
Thanks guys! So much to reply to, and multi quote would make the post too long.
@Bort - would have loved to put an acceleration vid up for you guys. I tried to take one and it is just not safe. Maybe I can try with a passenger but it is like those vids you see with a passenger in a 9 second car where they freak out. And I would rather not get arrested.
@Launch - I had wondered about that myself actually. Very hard to say for sure.
@aintskeered - very perceptive sir! The motor is still new. My cranking compression is improving but is not yet back to where it was before. As it wears in, it might pick up a bit.
@Tony - lmfao choo-choo train. It pulls like one! It was a long hard road for what was supposed to be a simple HCI swap. No kidding about Chevelle. I have not told many people how much he did for me, and I will save that for a different post to make sure he gets the spotlight he deserves.
