Took the Cobra to the track to use the "track dyno"

[Boogie70]

Well to follow up on a previous post I started concerning my dyno numbers with a Amazon ported eaton I took my car out to the track Friday night.

To give some history I have an Amazon port eaton, 2.93/4lb pulley combo, K&N FIPK, LPF HE, steeda wheel hop kit, and BBK X with Magnaflow catback. For tires I had some used 26x11.5x17 E.T. streets. The car was dyno tuned at pro-dyno and it made 513hp/563tq. I think the numbers are a little high but like I said in the other post the track will tell the story for me.

I drove my car to the track and iced my intake down for 20 minutes. The tires had 15lbs of air and I lit them up leaving at 3000 slipping the clutch.

My first run was;

1.98 60ft
7.89 E.T.
94.5 MPH

At this point I was thinking the tires wouldn't hold me. WRONG!
I dropped the tire pressure down to 11lbs and left at the same 3000rpms slippping the clutch. The car bogged down and almost cut off and here's what that pass was;

2.05 60ft
7.91 E.T.
95.1

Considering I bogged down and still ran 95 mph I knew the car had some mid 7's in it. I felt that the tire pressure was about right so the next pass I raised my rpms to 4500 and left like I stole it. The car hooked a lot better and while I really couldn't tell, some onlookers said the cars was still spinning or hazing the tires.
That pass I ran my best time.

1.70 60ft
7.53 E.T.
95.0 mph

Now I'm thinking I should leave a little harder to get more out of the car so
I raised my RPMs up to 5000 but it didn't help because on that pass I ran:


1.73 60ft
7.55 E.T.
94.99 MPH.

I regret not trying other tire pressures (lowering it)to see if I could get the 60ft down more but overall I was satisfied with the cars performance. So back to the dyno numbers question, I personally think the dyno numbers are off and that car is making anywhere between 470 and 485 at the rear wheels.

Oh yeah, I didn't run the vette because he broke a half shaft on his first run of the night. That had me little worried for my half shalfs.

 

[Boogie70]

No opinions or thoughts? I just want to know if you guys think the times are matching the dyno numbers. The car is 3850 with me in it so it has to be making at least in the upper 400s to pull that much weight down the track that fast with stock gears.

 

[Brandon03Cobra]

I was reading the first part of your post and was like that was dissapointing but after reading all of it the numbers seem to match from what I have seen.

My Cousin had a 86 GT with 4.10 gears on the same tires you have. Stock motor with 24lb injectors and K&N with 200 shot of nitrous and he ran the same time.

 

[Boogie70]

I was really hoping for some 7.20s. That was my first time out so I think if I play with my launch rpms, shift points and tire pressure I may be able to do a little better.

 

[slowmoving1]

well I have ran 11.7x @ 117-119 on a unported eaton with 2.8 upper,steeda cold air, SCT canned tune,
The 1/8 mile times were 7.49-7.5x @ 92-95
IMO your #'s are high but they are just #'s. what kind of dyno? sae or std #'s

What was the weather like?

 

[Boogie70]

I ran the car at night and the temp was about 75 and kinda humid. I asked Dan at Pro-Dyno tune what the numbers were as far as corrected or SAE and he said they were SAE corrected. I thought their was a chance that they might be on par because he Dynoed a 427 Roush and it made 385hp. I read somewhere that's about what they make to the wheels.

What kind of tires were you running and do you have stock gear? What was your 60ft?

 

[slowmoving1]

I ran the car at night and the temp was about 75 and kinda humid. I asked Dan at Pro-Dyno tune what the numbers were as far as corrected or SAE and he said they were SAE corrected. I thought their was a chance that they might be on par because he Dynoed a 427 Roush and it made 385hp. I read somewhere that's about what they make to the wheels.

What kind of tires were you running and do you have stock gear? What was your 60ft?

4.10 with 28 inch tall tire= about 3.73 , also SRA
60ft was 1.69-1.77 on drag radials
I'm sure most guys that have ported eatons trap about 99-101 in the 1/8
may be i missed it did you have drag radials?
Your car ran good with more seat time and getting your launch dailed in you should run alot better. Get some slicks if you really want to fly.

 

[Boogie70]

I was running 26x11.5x17 E.T. streets with the stock gear. Now I know I could have done a lot better if I had 4.10s gears and some 28" tall tires. Too me the 26 inch tall tires on a 17" rim does not have enough sidewall to take the shock from a hard launch but hey I got to work with them being that I just got them even though they are used. I think I can drop another tenth off my time by playing with the tire pressure.

 

[Ralo]

What tires are you running?

 

[96stanggt]

Sounds like you getting the car dialed in pretty well toward the end of the day. You're guess about the numbers is most likely right, with trapping 95mph you're most likely making about 480-495rwhp and similar tq. Those old Amazon ports made good power, but not near what the newer ports make. I don't think I've ever seen one make over 500rwhp.

 

[AmazonTuning]

Those old Amazon ports made good power, but not near what the newer ports make. I don't think I've ever seen one make over 500rwhp.

our ports were comparable to a Stage 1-2 .. we never developed past that stage and several year ago stopped doing our own porting.

 

[96stanggt]

our ports were comparable to a Stage 1-2 .. we never developed past that stage and several year ago stopped doing our own porting.

I know, that's what I was trying to say. The ports you guys did were on par with what Steig was doing at the time and made/make good power. But seeing the bigger numbers these newers ports are seeing is unlikely.

 

[AmazonTuning]

I know, that's what I was trying to say. The ports you guys did were on par with what Steig was doing at the time and made/make good power. But seeing the bigger numbers these newers ports are seeing is unlikely.

we use STIEGEMEIER and POSI PERF now for our porting needs..:beer:

 

[96stanggt]

we use STIEGEMEIER and POSI PERF now for our porting needs..:beer:

Awesome!

 

[yosemiddysam]

Well my last dyno numbers were 540HP 518TQ with a ported eaton and a 2.76 upper only. I ran almost the exact time as you so like every one else is saying....They are just numbers. Mine was 1.7 60ft and a 7.520 at 97.524MPH

 

[Boogie70]

Ralo, I was using ET street drags.

I guess I got into this game a little late as far was which supercharger to get. To be honest my plans were not to modify the car but sell it since i got a good deal on it. Now that's out the window and my 88 coupe is starving for some attention.

I looked at my dyno numbers and it appears they were not corrected numbers. I figure using 4% for SAE correction I may be making 496/514 instead of 517/536 give or take a few ponies. I still have the original charger and I'm thinking about getting it ported but at this point I don't know if it's worth going through all that trouble for 20-30 rwhp- swapping chargers, tuned again, and more than likely being in the need of injectors, maf and BAP.