need tips for dyno tune

that looks like it will be a rather fun to drive street/strip BBC performance combo,
that has avoided one of the major problems I see all too frequently in other engines like the all too common, 496 BBC, which many people over cam, over carb, and use too large a cylinder head on,etc.
and thats caused by failing to think through and match the drive train gearing too the cam duration , compression, fuel octane and engines intended and designed operational rpm range.
Cheers
 
many guys seem mesmerized by the need to post 600-hp-700-hp peak numbers from a 496, BBC,
and while 600 hp plus numbers are not hard to reach if you build the engine for max power,
with the correct cam, compression, heads , intake ,etc.
the problem with that is, the engine built to produce that impressive peak power will almost always ,
be a p.i.t.a. to drive on anything approaching a longer trip.
because the cam duration required mandate,the engine run exceptionally well in the 5000-6500 rpm range, and the need for the cars drive train too be geared too match the engines power range, the combo youve built will be more street driver friendly and may be more fun to drive on the street.
you can reasonably assume you've lost about 18% in drive line power loses,
so your engine is more than likely making about 18% more power than the dyno shows.
I'd also point out that as you learn to tweak/tune the combo youll be able to squeeze a bit better,
power.
keep in mind a 3.31:1 rear gear should allow you to get semi reasonable fuel economy, for an engine that size ,
if you drive that manual trans and keep the rpms generally under 3000 rpm,
something you would be unlikely to do with a properly set up 600 hp plus engine.
and yes I'm fairly sure theres some rather easy extra power available if you make minimal changes,
but get comfortable driving the car and do your research before making more changes.
 
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Yes the fuel economy is an eye opener. I did a 180 mile trip about a month ago and averaged 15.3 mpg.
I also selected the parts to last for a long while under low maintenance. Where is the fun if you are forced to always be tuning it and adjusting the valves. Even more of an impact if you needed to pay someone to do it for you.

I kept a spreadsheet of all the parts, part number, where I purchased them and machine shop costs to build this. End to end I think I'm at $18k Water pump to Tires since I do all my own work.
I'll need to update this one to include the actual purchase (~$7k) of the transmission, scatters shield, clutch, driveshaft, yokes, cross member, shift lever & ball, speedo gear, wheels and tires.
 

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whats your current air cleaner too hood clearance?
one rather restrictive part, is that intake.
I understand your not dealing with a great deal of hood clearance but a less restrictive intake would wake up the car.
btw what does a compression check show your cylinder pressure to be?
did the dyno test info include your ignition advance curve and your fuel/air ratio every 500 rpm?
did it show exhaust back pressure in the collectors, and intake plenum vacuum?
knowing detailed info like that can be rather helpful.


  1. Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
  2. Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025.
  3. Torque (N.m) = 9.5488 x Power (kW) / Speed (RPM)
  4. Power (kW) = Torque (N.m) x Speed (RPM) / 9.5488.

or go the simple route
5. The equation to calculate horsepower is simple:
Horsepower = Torque x RPM / 5,252.


so as an example

350 ft lbs at 3000 rpm/5252=200 hp
350 ft lbs at 4000 rpm/5252= 266 hp
350 ft lbs at 5000 rpm/5252=333 hp


minor changes in the input data , or sensors placement
,ignition advance curve, exhaust backpressure and fuel/air ratios,
oil levels and temps, coolant temps, fuel octane, plug gaps, battery voltage,
and tire to drum traction,
can screw up the output results on any dyno, many dyno operators,
are rather unskilled/knowledgeable in the machine's precise calibration or operation.
they don,t change anything , from the original parameters
they just connect the car to the dyno and run the car
this can be one reason you get varied results at two different dyno tests.

read threads
http://garage.grumpysperformance.com/index.php?threads/calculate-your-rear-wheel-horse-power.4788/


http://garage.grumpysperformance.co...late-gear-ratios-and-when-to-shift-calcs.555/


http://www.chevydiy.com/how-to-build-chevy-big-blocks-intake-manifold-guide/

http://garage.grumpysperformance.co...ting-big-block-chevy-454-cam-dyno-test.10181/
 
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I am thinking the same thing about the intake manifold and will check those links... was looking at the Brodix HV2017.
The dyno did not give back pressure readings.
The ignition curve is 18° initial and 38°all in by 2500RPM. As for the AFR by RPM... I believe I have that. Although at the start of each run there was an anomaly of over lean followed by over rich that I looked close at later that night.
The car is a manual trans and the car needed to be in 3rd to stay arond 100mph at WOT. They went through 1st and 2nd then once in 3rd mashed the throttle for the pull.
The issue is that he lifted the throttle between shifts (closing the plates) and it invoked a lean stage as all the fuel was sucked out of the manifold. I was able to prove that with my logs when I checked my AFR to RPM to TPS. Then when the throttle was mashed the EFI over shot trying to compensate for the lean. I feel that if the guy held the throttle at 2500 for 5 seconds once in 3rd the AFR results would not look so odd.
 
Update for Grumpy:
I did check the compression and they are a uniform 150PSI although as I think about it that was with the butterflies closed.
 
that sounds like its reasonable and consistent, and should indicate everythings in good shape, mechanically
 
The HVBrodix 2017 will not fit after doing my research it is ~2" taller than my existing manifold. Currently the air cleaner to hood mat clearance is zero. I used clay on the air cleaner and closed the hood. It squishes down to about 3/8 to 1/2".
I'm using a 2.5" drop base air cleaner and a 14" K&N filter.
 
yes thats a common issue , and why many guys resort to ram-air type hood that provide extra hood clearance
 
Not going to change the hood... period. Love the original look.
If I need to alter the hood to gain a few HP then I guess I'm not as sharp as I hope I am. If I'm altering the hood it will be for an 8-71 and not a taller manifold.
 
Update: no new Dyno pull yet although I did install the Brodix HV-2017 after reassessing the measurements. The net gain in manifold height was zero.
The engine has really woken up above 5600 or so and pulls hard to 6500... so by the Seat-O-Da-Pants meter I am expecting improvements from the dyno results.
She still drives well.
Cheers
 
Actually I did make another upgrade... added an externally mounted oil filter and now running a WIX 51794 oil filter and picked up roughly 2 more quarts of oil putting me at 9qt total. Running 5/8” Stainless from the block forward then go to -10an hose and remote filter.
Very pleased with that and will post the parts detail shortly.
 
several clear pictures from various angles of the car and engine compartment would me helpful here.
 
Parts list and some photos.
OilCooler.pdf is a clear schematic of the parts uses to completed this although te images may reflect some blue parts I used strictly black.
BlockPad is the looking from below up at the original oil filter pad and where the Canton 22-580 adapter is installed.
ForwardBulkhead is a view of the metal plate securing the forward end of the 5/8 stainless lines and the 90 degree AN fittings. I chose to use sheet metal rather than plate because I figure the stainless will expand and contract with heat so I wanted some flexibility for that to happen without added strain on the fittings.
BulkHeadAndFilter is a similar view although you can see where I hung the oil filter. I used 1/4" plate to make a plate for the remote filter mount to hang from.
DownViewNewFilterLocation is exactly as it sounds. The filter is suspended high enough to avoid road debris and with enough clearance to still get a hand around it for replacement. It sets mounted to the Camaro front subframe, behind the radiator and above the radiator drain.
Once installed and running a few days I found it dripping some oil so that needed to be fixed. The problem was I did not have a crowsfoot large enough to tighten the oil fitting into the base...
Fortunate enough to do my own work and nice to be a fabricator at heart. so down to Home Depot and purchased a few wrenches to make my own crowsfoot.

BTW... this stuff ain't cheep.
 

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I love the way some guys have the skill and tools to custom fabricate , any unique parts or tools required to get the job at hand done!
 
My father was a heavy equipment repairman. Always working where ever the job was and if he busted a socket or needed a tool he did not have... he either fixed it or made it on the site.
A generation that is fading away.
 
Well I finally made it back to the dyno and left there scratching my head.
Changes since the last run.
Replaced the fully divided duel plenum, port matched manifold with the Brodix HV2017.
Replaced the 1.7 rockers with 1.8s increasing lift to just under the max flow for the heads.
For the purpose of the test I used a stainless salad bowl with a coarse screen rather than my low profile base and filter (see attached results).
My final test was simply replacing the salad bowl with my custom base.

The motor made no significant increase in torque or HP... from my earlier series... thus scratching me head & digging through the data... I wonder if my O2 sensor is due for replacement since I saw variation between mine and the one used by the dyno in the other collector.
I pulled the plugs and all 8 looked real clean but consistent.
If my sensor is failing it may not be keeping the EFI accurate on the rich AFR SIDE.

The only real plus of the night was that the low profile air cleaner with the K&N had no measurable impact on torque or HP either. This supports my theory that EFI does not care about laminar air flow.... just get it in there.
The dyno graph shows essentially noise level differential between the salad bowl (in red) and the low profile base and element (in black).
I have attached relevant photos.
 

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It would have interesting to see how a velocity stack would have compared to the salad bowl.

So what was your lift with the two different rocker ratios? The camshaft link does not say what
ratio was used to get the 540/560 lift.
 
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