Airwolf Results!!!

Tech Related Discussion

Postby chevybowstik » Sun Mar 14, 2010 8:08 pm

TRMNATR is deadon in his post! 800-1000 rpm shift over flash stall works great in a powerglide and let the motor run out the back door in high.I have to agree with everything he said as he has the timeslips to prove it! My experience with 383-406s and glides you need a fairly loose convertor for your engines powerband and after the launch the motor is never below the flash stall speed so you need to cam for that powerband like he said. After the shift from low to high the motor should stay above the flash rpm,usually about 500rpm higher if I remember.
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Postby trmnatr » Sun Mar 14, 2010 8:10 pm

chevybowstik wrote:Banjo i ran a very similar cam in a 406.Car weighed 3150 lbs with powerglide and 4.30 gear 9by 30 slick.Was a 70 nova,cam was 260-266 with a 108 separation.I agree with you as it was very easy to drive being a footbrake car.I swapped cams to a 265-275 on a 104 separation and this NOTICEABLY made more torque as the convertor loosened up 500 rpm just with the cam change.Remember bracket racing is all about reaction time and et repeatability! But being gearheads we always want to go faster! Its like a disease but a good one to have!Great job Chad and DRJ


Just some numbers people dont look at

Here is my theory that works for me with 23 degree engines

Lets take a cam of 260/268 @.050" on a 110 lobe seperation with ZERO advance, say this is the current cam that works well. The timing will look like this
IVO 20btdc IVC 60abdc
EVO 64bbdc EVC 24atdc

IMO one of the most important events is IVC then IVO, then OVERLAP PERIOD then OVERLAP FLOW

Lets take the same cam, but you advance the intake centerline from 110 to 106 intake centerline
IVO 24btdc IVC 56abdc
EVO 68bbdc EVC 20atdc

Now lets look at the same camshaft but on a 106 lobe seperation with zero advance
IVO 24btdc IVC 56abdc
EVO 60bbdc EVC 28atdc

Now IMO we need to retain that IVC, I like the early EVO on a N/A engine because it allows the cylinder more time to BLOW DOWN before the piston passes BDC and has to push high pressure exhaust gasses out, So now lets look at the camshaft on a 106 lobe seperation with ZERO advance but 8 degree's more duration than the original camshaft
IVO 28btdc IVC 60abdc
EVO 64bbdc EVC 32atdc

Usually I would run this cam above ^^^ to replace the original cam with 4 degree's advance, But I would run 1.6 exhaust rockers to help blow the cylinder down better and it has shown ET for us. If you notice in bold, the two most important points in my opinion are the same, IVC & EVO

So lets look at the camshaft specs I suggested, 278/284 @.050" on a 106 lobe seperation with ZERO advance
IVO 33btdc IVC 65abdc
EVO 68bbdc EVC 36atdc

Notice even though the duration of the camshaft is much larger the two most important parts are about the same, for better performance IMO, The IVC & IVO. The IVC and EVC will just make it perform even better with close to the same specs of the original IVC & EVO

I will explain my opinion on overlap period and overlap flow shortly that has worked very well for us
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Postby banjo » Sun Mar 14, 2010 8:10 pm

I thank you for you constructive comments. This weekend, It was shifting at 7000 rpms. I forgot to bring the cable to reprogram my ignition box to change the setting. Motor made peak power at 7000 rpms, so i would expect to be shifting in the 7400-7500 range. I feel there is at least .05 in that. Time slip will show on friday.

I will check tomorrow to see where the stall went on the converter. Before it was about 5700.

Chevybowstik, what kind of et did you pick up?
Bill Simpkins
Empty Pockets Racing
74 Chevy Nova
smallblock 406 with the original Airwolf heads.
1/8 6.15@110mph (11/11)
1/4 9.87@131 (02/13) On the rev limiter.
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Postby trmnatr » Sun Mar 14, 2010 8:13 pm

chevybowstik wrote:TRMNATR is deadon in his post! 800-1000 rpm shift over flash stall works great in a powerglide and let the motor run out the back door in high.I have to agree with everything he said as he has the timeslips to prove it! My experience with 383-406s and glides you need a fairly loose convertor for your engines powerband and after the launch the motor is never below the flash stall speed so you need to cam for that powerband like he said. After the shift from low to high the motor should stay above the flash rpm,usually about 500rpm higher if I remember.


Funny you say that, We had a bet the engine wouldnt run 10.30's off the trailer so we had to take a photo of the time slip lol

Watching the car leave with the crappy track I thought it was a 10.60 until I sa it rolling in high gear

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Postby trmnatr » Sun Mar 14, 2010 8:14 pm

banjo wrote:I thank you for you constructive comments. This weekend, It was shifting at 7000 rpms. I forgot to bring the cable to reprogram my ignition box to change the setting. Motor made peak power at 7000 rpms, so i would expect to be shifting in the 7400-7500 range. I feel there is at least .05 in that. Time slip will show on friday.

I will check tomorrow to see where the stall went on the converter. Before it was about 5700.

Chevybowstik, what kind of et did you pick up?


Shift at 6,400rpm and let that b!tch run out the back door, Should be a solid .1 to .15 faster
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Postby chevybowstik » Sun Mar 14, 2010 8:20 pm

Banjo,to be honest with you I cant remember what the car picked up! I know it ran quicker but I dont want to give a guess to you.The convertor loosening up has always stuck in my mind! They are like mini dynos in your car! TRMNATOR and my experiences seem to coincide though.That 406 with the 260-266 cam on a 108 sounded like a hot streetcar compared to the tighter larger cam!Your car runs really well and is just like the combos I have run.You use a dominator on your footbraker right?
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Postby DiscoNova » Sun Mar 14, 2010 8:28 pm

Awesome news Getting very Excited to recieve my New AirWolfs! Job Well Done! 8)
Slowly getting stuff back together
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Postby banjo » Sun Mar 14, 2010 8:30 pm

I have a dominator that I have been playing with, but I am not happy enough with it to compete with it.

I can try and shift lower, but I can tell you before, when I went from 6600 to 7000 it picked up .06. But that is with the 4.10 vs the 4.56 gears I have now. The train of though I was always taugth was to overrev the engine with a powerglide to help it with a tall gear change. Short shift a 3 speed.

As I said I am going to tune on what I got for a little while then start looking into a cam change.

Bill
Bill Simpkins
Empty Pockets Racing
74 Chevy Nova
smallblock 406 with the original Airwolf heads.
1/8 6.15@110mph (11/11)
1/4 9.87@131 (02/13) On the rev limiter.
Fourtenposi@yahoo.com
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Postby trmnatr » Sun Mar 14, 2010 8:39 pm

Overlap Period and Overlap Flow (This will help you Bill when you get to tuning, You have ALOT left there)

Camshaft #1
308/314 @.020" 278/284 @.050" .670"/.670" 106 lobe seperation, zero advance, timing @.050"
IVO 33btdc IVC 65abdc
EVO 68bbdc EVC 36atdc

Camshaft #2
307/316 @.020" 278/284 @.050" .678"/.657" 106 lobe seperation, zero advance, timing @.050"
IVO 33btdc IVC 65abdc
EVO 68bbdc EVC 36atdc

Overlap Period on camshaft #1 = 69 degree's at .050"
Overlap Period on camshaft #2 = 69 degree's at .050"

So the overlap period on both cams start at 33btdc and go from there to TDC then from TDC to 36atdc , So we all can agree that roughly the center point of the overlap starting and ending on this given design is TDC, Correct?

Now lets look at the valve lift @ TDC , Should be the same, Correct? One would think so after all camshaft #2 is a little more intense and just a hair longer exhaust duration, lets look

Camshaft #1 (these specs are off a degree wheel/DI)
Lifter rise @ TDC
Intake .183"
Exhaust .195"

Intake lift @ the valve @ TDC
.183" x 1.6 rockers = .293" - .012" lash ramp design = .281"

Exhaust lift @ the valve @ TDC
.195" x 1.6 rockers = .312" - .012" lash ramp design = .300"

So Camshaft one is .281"/.300" at the valve at TDC

Camshaft #2 (these specs off degree wheel/DI)
Lifter rise @ TDC
Intake .179"
Exhaust .186"

Intake lift @ the valve @ TDC (more intense lobe off the seat)
.179" x 1.6 rockers = .286" - .016" lash ramp = .270"

Exhaust lift @ the valve @ TDC
.186" x 1.6 rockers = .298" - .018" lash ramp = .280"

So look at them side by side, Lift at the valve
Cam 1
.281"/.300"

Cam 2
.270"/.280"


Now we have camshafts here that one would think are gonna be the same but the cylinder filling is gonna be different with both cams due to overlap flow, But they have the same overlap period

So for some engines you can alter the lobes, lower the overlap period and still have the overlap flow of a larger camshaft
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Postby trmnatr » Sun Mar 14, 2010 9:09 pm

Dr J's Performance wrote:bill thanks for putting forth all the effort, and posting your results. Next time out you'll need to turn up the RPM's to see what she'll do :shock:


If he can shift ~6,400rpm and turn it higher in high gear, It is gonna pick up .1 to .15 there alone !!!!!!!!!!!

Banjo, Remember if your shift light comes on at 6500rpm your shifting 6800-6900rpm depending on how quick you are and how fast the engine revs , I would say 400rpm knowing what our junk does

If the shift light is set to 6000rpm, you will be hitting 6300-6400rpm shifts

Keep that in mind while tuning
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Postby chevybowstik » Sun Mar 14, 2010 9:32 pm

On the subject of overlap flow once again TRMNATR is correct about overlap degrees and overlap flow.I also check valve opening at TDC between cams,this is where somepeople overlook the effect of higher ratio rockers.Using Ts examples if you just change rocker ratio you achieve more overlap triangle because of the ratio increase.I have gone from 1.5to 1.7 on an old cam dynamics flat tappet which was installed at 99 intake centerline the intake valve really was opened alot at TDC!Speaking of IVC and EVO I used an old Lunati super stock grind which was 16 degrees bigger on the exhaust and was on a 104 lobe separation,I installed it at 100 ICL the IVC was the same as old cam but the exhaust opened a bunch earlier and this cam performed very well as everyone thought the early exhaust opening would KILL the engine it did not hurt midrange power at all and made a bunch of power past peak! Just some thoughts!Banjo I like the idea of a 2 circuit dominator in a footbraker COOL! As I use one on a mild 454 BBC
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Postby trmnatr » Sun Mar 14, 2010 9:44 pm

chevybowstik wrote:On the subject of overlap flow once again TRMNATR is correct about overlap degrees and overlap flow.I also check valve opening at TDC between cams,this is where somepeople overlook the effect of higher ratio rockers.Using Ts examples if you just change rocker ratio you achieve more overlap triangle because of the ratio increase.I have gone from 1.5to 1.7 on an old cam dynamics flat tappet which was installed at 99 intake centerline the intake valve really was opened alot at TDC!Speaking of IVC and EVO I used an old Lunati super stock grind which was 16 degrees bigger on the exhaust and was on a 104 lobe separation,I installed it at 100 ICL the IVC was the same as old cam but the exhaust opened a bunch earlier and this cam performed very well as everyone thought the early exhaust opening would KILL the engine it did not hurt midrange power at all and made a bunch of power past peak! Just some thoughts!Banjo I like the idea of a 2 circuit dominator in a footbraker COOL! As I use one on a mild 454 BBC


HA bet it was not a Lunati or at one time it had an Erson in it, The two popular ones and both worked very well !!!!!!!

Everybody went back and fourth between the Erson and Lunati, I had to dig up the two just to remember them, I wonder if they still sell them off the shelf :lol: :lol:

Lunati
301/317 @.020"
268/284 @.050"
.606"/.660" with 1.5's :lol:
105 lobe seperation

Erson
294/308 lash duration
268/282
.615"/.645" with 1.5's :lol:
104 lobe seperation

Two old cams but worked very well a long time ago
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Postby 358T » Sun Mar 14, 2010 10:16 pm

trmntr, are you saying short shift it but give it more rear gear?

I have to say I'm a little skeptical that shifting Bills engine at 6400 is going to pick it up. I get the 800-1000 rpm window thing but it normally applies when shifting past peak hp and having a converter that stalls just a little short of peak power.

IMO, I say that with no other changes except the shifting at 6400 instead of 7000 or 7400 bills car will slow down.
Scott

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Postby trmnatr » Sun Mar 14, 2010 10:19 pm

358T wrote:trmntr, are you saying short shift it but give it more rear gear?

I have to say I'm a little skeptical that shifting Bills engine at 6400 is going to pick it up. I get the 800-1000 rpm window thing but it normally applies when shifting past peak hp and having a converter that stalls just a little short of peak power.

IMO, I say that with no other changes except the shifting at 6400 instead of 7000 or 7400 bills car will slow down.


If he had a 6,000rpm converter it would run better shifting ~7,000rpm

Due to his converter and a 1.76 low gear in a heavy car, he is running too far away from the converter and loading the engine

Does the engine have the power to shift at 7,000rpm, yup

Will his car ET faster shifting at 7,000rpm, my bet is No. Loading the engine too hard in the car plus when you go from 4.11 to 4.56 you will loose converter stall/flash due to less work for the converter to do

4.88 to 5.38 I lost 700rpm IIRC

4.56 to 4.88 in the Camaro I lost 200-300rpm on the converter

You hit the nail on the head with the converter :D
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Postby trmnatr » Sun Mar 14, 2010 10:24 pm

And Bill, I'm not knocking your combo, Just trying to show you that you have a HE!! of alot more ET laying right in front of you

You have a damn nice combo, Very close to our larger 406

We may have a 9.90/10.0 pass with a 6.30ish run Sunday or faster :lol: :lol:
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