Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2146886
09/03/16 05:56 PM
09/03/16 05:56 PM
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Joined: Jan 2003
Posts: 1,793 Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,793
Windsor, ON, Canada
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Oh you guys...I have an adjustable shift-light on my tach...sorry...I've gotten used to it so much that I had actually completely neglected to mention it. So when superchuck posted the link to the shift-light product the proverbial lights finally went off in my head...LOL. I pre-set my tach to have the light go off at 6300 RPM, so by the time I react and the shift is completed the tach pegs up to about 6500 RPM. My son put together a little compilation of that day's events, you can find it on YouTube.
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2146908
09/03/16 06:45 PM
09/03/16 06:45 PM
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Joined: Aug 2003
Posts: 43,718 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,718
Bend,OR USA
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My suggestion to jet the carb. up richer until the MPH slows down in the 1/4 mile is to verify adequate fuel delivery (EDITED Once it starts to slow down jet it back to the best MPH )T.Q. carbs can make a hoop of HP when jetted correctly, jet it up and try opening the rear door some more until it slows down
Last edited by Cab_Burge; 09/04/16 02:00 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2146916
09/03/16 07:06 PM
09/03/16 07:06 PM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Since you average MPH is up I'd say your power is up. poor track prep and more power lead to more tire spin so loses down low. and weather and wind can affect it too. And if you say your seat dyno around town tells you it has more low end the gain was probably gone in tire spin. work one thing at a time try to get 60" more consistent and quicker then try moving rpms at shift up and down. do a log.
Could be that you do not spin at the hit and start spinning after 10 to 20 feet as you come into power band and carry that spin past 60'
Last edited by Dodgem; 09/03/16 07:35 PM.
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2147059
09/03/16 11:24 PM
09/03/16 11:24 PM
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Joined: Jan 2003
Posts: 1,016 Richmond Twp. Mi.
Mr340
super stock
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super stock
Joined: Jan 2003
Posts: 1,016
Richmond Twp. Mi.
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You didn't mention what heads you have. If they are cast iron at 10.7 cr I would recommend mixing some 100 or 110 octane fuel with your 93 pump gas... Yes, these are factory 596 castings, somewhat heavily re-worked (porting mostly, see this other post for some specifics) but with 2.02 and 1.60 valves. I never thought of going beyond the 94 octane if that octane level was not causing me detonation issues...wouldn't higher octane atually burn slower? you may be detonating but not hearing it over other noises. I had a similar combo with a 340, iron heads, quick advance, 10.4 cr, 175 psi cranking, would run fine, no audible knocking but at the track it would run .5 quick on a 50/50 mix. I think it's worth a try. you do need to get your 60' nailed down but your MPH will tell you if it helps.
Last edited by Mr340; 09/03/16 11:28 PM.
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2147277
09/04/16 01:26 PM
09/04/16 01:26 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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IMO, those 60' times are terrible for a combo like that with a 4k converter. If you're sure it's not spinning, then either the motor is really soft down low or the converter is suspect. I would put a white stripe on the tire and have someone video the rear tires on the launch and verify it's not spinning. No reason a hi-12/low-13 second car shouldn't be dead hooking.
The speed also seems low to me for what the heads flow, cam size, cr, etc. How do the converter slip numbers look?
Fwiw, I think you're shifting too high, but that's easy to sort out.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2147306
09/04/16 02:13 PM
09/04/16 02:13 PM
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Joined: Jun 2006
Posts: 5,173 CT
GTX MATT
master
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master
Joined: Jun 2006
Posts: 5,173
CT
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If that converter really stalls at 4000 RPM I think all the torque you added with the RPM intake is going out the window, thus your 60 times that haven't changed. You're just losing a little top end, which is probably offset by your head work.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2147357
09/04/16 03:35 PM
09/04/16 03:35 PM
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Joined: Feb 2003
Posts: 1,942 Metro Detroit
OUTLAWD
top fuel
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top fuel
Joined: Feb 2003
Posts: 1,942
Metro Detroit
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The tight shocks, clamped springs and sway bar explain why the car looked "stiff". Very little movement front and rear. The video confirms this.
I've never had a good handling car that I've taken to the track, so I am not sure how to go about getting weight transfer and hook. If the shocks are easily adjusted, you could maybe loosen up the front rebound at the track, then tighten it back up for the drive home.
Faster, Faster until the thrill of speed overcomes the fear of death...
71 Swinger - slowly collecting dust/parts 66 Belv. II - just a streetcar 88 Mustang - turbo LS beater
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Re: Combo changed, but ET still the same?
[Re: fast68plymouth]
#2147969
09/05/16 01:34 PM
09/05/16 01:34 PM
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Joined: Jan 2003
Posts: 1,793 Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,793
Windsor, ON, Canada
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IMO, those 60' times are terrible for a combo like that with a 4k converter. If you're sure it's not spinning, then either the motor is really soft down low or the converter is suspect. I would put a white stripe on the tire and have someone video the rear tires on the launch and verify it's not spinning. No reason a hi-12/low-13 second car shouldn't be dead hooking...
I am somewhat convinced now (given the forum feedback) that I still probably have a pretty decent amount of time spin @ launch. I will do the white stripe on tire trick next time out to really get a good measure of this. The converter is a custom built (for this car&combo) 9.5" Dynamic Converters piece that's spec'ed out to stall at 4K. I believe it flashes to around 4K@launch, but I have always staged @ 3000 or 3500 and only did the 4K launch once. ...The speed also seems low to me for what the heads flow, cam size, cr, etc.How do the converter slip numbers look?... I also think this is a tad slow for the combo I built..LOL...but I always attributed that conclusion to my "wishful thinking". Regarding the converter spli numbers...umm...help me out, how do I calculate this? The Nitton NT555R drag radials I'm using are 27.75" tall. Paired up with my 3.91 SG rear end, am I looking at calculating the theoretical speed @ given RPM and comparing that to what my gauge is actually showing?
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Re: Combo changed, but ET still the same?
[Re: GTX MATT]
#2147973
09/05/16 01:39 PM
09/05/16 01:39 PM
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Joined: Jan 2003
Posts: 1,793 Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,793
Windsor, ON, Canada
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If that converter really stalls at 4000 RPM I think all the torque you added with the RPM intake is going out the window, thus your 60 times that haven't changed. You're just losing a little top end, which is probably offset by your head work. As I sat down logging the 1/4 numbers into my spreadsheet that is what I started to think. The street manners feel I referrenced earlier is that the Performer PRM is a much more responsive intake. The Strip Dominator on the other hand is soft down low, however, the benefit last time out to the track with that single plane intake seemed to have been that even with the full 32 psi tire pressure I am pretty certain there was very little (maybe none?) tire spin. So as you pointed out I am wondering whether now I have moved to a better torque output and with the additional head-work I provided for a tad more flow to "keep-up" with the higher RPM performance of the single plane??? Sorry...all theory at the moment and really I'm thinking out loud on this one.
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2148071
09/05/16 04:19 PM
09/05/16 04:19 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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Going off a 27.75" diameter, the moroso chart shows about 4880rpm for 103mph and 3.91 gears. That's close to 16% slip, which IMO is way too high for a combo like that. Should be well under 10%. 3600lbs, 103mph shows just a tick over 300hp on the moroso chart. The motor combo should make an easy 400hp at the flywheel. My experience is that if the car is working even remotely good, you should be able to run within 10% of the predicted ET for a given power/weight ratio. In your case, 360hp(90% of 400), 3600lbs...... Shows 109mph.
I'm going to dig out some of my old VHS tapes and see if I can find some passes from my Dads old 79 Cordoba...... From around 1993. The combo was .040 360 with some of the old flat top trw pistons for a 71 360 application(8.8:1 actual cr), home ported( by my dad) 1.88 360 heads(don't recall the numbers.... Might have been J heads) converted to 2.02(probably flowed a max of 225-230). Torker II intake, 650dp Holley, crower solid cam(#31312)that was 250-254@ .050,108lsa, .540-.550ish lift, hooker 1 3/4 headers. 9" Fairbanks converter I bought at a swap meet, 4.56 gears, 10.5 x 28 slicks, 3900lbs race weight. I'll double check this if I can find the videos, but as I recall it ran 12.60's and I think the speed was in the 106-108 range. That shows about 365hp on the moroso chart, which would work out to 405hp if you figure a 10% loss for being in the car. That motor was dyno tested prior to that with a mp509 cam in it instead and made right about 400hp.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2148099
09/05/16 04:49 PM
09/05/16 04:49 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
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I Live Here
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For a comparison with another car with a known hp, that's also not set up for drag racing at all..... I have a bone stock 2012 mustang gt. 6 speed, 3.31 gears, oem tires. The only thing that's not as delivered is its had a few oil changes and I put in a pcv system catch can. Horrible tire frying launches(2.10 best 60') and less than stellar shifting on my part netted a best of 13.42 at 109.8mph. The car weighs 3500lbs + me, and I'm 240. The moroso chart shows 380hp for 3740 and 109.8mph.... Motor is rated at 412hp.
IMO, you really seem to have two issues...... The 60' is off, and the speed seems pretty low.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2148749
09/06/16 01:13 PM
09/06/16 01:13 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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On the other end of the spectrum, to show how good things can run without a bunch of fancy parts, when the car is purpose built to go down the drag strip. 1980 Dodge Mirada running in I/SA. Low comp 360, 308 heads with 1.88 valve and no porting. Stock intake and a TQ carb. .420-ish lift cam, headers. 8" converter, drag shocks, slicks, 4.56's(I think). Min weight is 3410....... It's gone 11.70's at 113-114. That shows 385hp on the moroso chart.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2149722
09/07/16 04:35 PM
09/07/16 04:35 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
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So. Burlington, Vt.
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All good advice to address the poor 60' issue..... But still need to find the missing 6mph.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Combo changed, but ET still the same?
[Re: Diplomat360]
#2150367
09/08/16 02:22 PM
09/08/16 02:22 PM
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Joined: Jan 2003
Posts: 14,531 So. Burlington, Vt.
fast68plymouth
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I Live Here
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So. Burlington, Vt.
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For sure, it needs to be verified if it's spinning or not as the first course of action. If it's dead hooking and still only runs 1.9-2.0 60' times, to me that would be an indicator that perhaps the poor 60' times and low mph are related to power output.
Fwiw, my heap always worked better leaving at a much lower rpm than the op is. I like to leave at the lowest rpm I can and not have any kind of bog...... Usually 1800-2200, which gives the motor a chance to get a run at the converter, and can often be worth another 1-200 in flash stall speed.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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