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  #21 (permalink)  
Old 08-17-2015, 10:32 PM
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In a nutshell: you have a good engine built by a pro. Tuned by a pro, it made good power. Now, some time later, it was tuned by another pro, and it did not make good power.

So, the question is: What changed? Something broken? Something failed? PO changed something, like the cam?

Time for some serious investigation to find the answer to that question. I would start with these things:
- basic tune up: plugs, wires, cap, rotor.
- pull the valve covers, and check all the valves and springs.
- adjust the rocker arms, again.
- compression check, wet and dry
- leak down test
- coolant system test, rule out a bad head gasket.

Careful diagnosis now will save time, money, and frustration later.
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  #22 (permalink)  
Old 08-18-2015, 04:54 AM
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Quote:
Originally Posted by Ace23 View Post
My comments about a LS7 where aimed at how docile they are being a FI 427. I'm not making a single move until I have more information but I'm saying I would want to know the options for going to fuel injection while keeping a Windsor setup. From the research I have gathered I would not want to go to one of the self tuning.....weekend warrior install wet manifold FI setups that seems to basically be a fuel injected carb. It seems like the stack injection or port injection setups are more expensive but potentially deliver the best results. My current rpm limit is 6500rpm but I've never shifted it about 6000rpm. My dyno results where showing max power output around 5800rpm. My comment about 7000rpm was that this is a street car and I'm not looking to turn those types of RPM nor want a motor that makes all its power up top. I'm not disputing something is up with the power output but Its yet to be found. I bet that nitrous is insane....its not my thing but it makes some nasty torque. Are you using a progressive system or are you hand cuffing yourself to the steering wheel and just praying?
*Timing-advanced it in between the dyno pulls until it was shown to lose power.
*Air filter removed on dyno- gained a whopping 4hp
*Exhaust setup is 2" headers through 2.5" Firefly stainless side pipes
*Brand new QF 750......when you go full throttle it was visually inspected and it opens all the way up
*Cranks, idles and runs fine and I would get in it and drive 500 miles tomorrow. As mentioned previously I need to get it on the local dyno jet and see what it makes. If it was right I would expect it to make about 450-460rwhp. If it made 360rwhp on a mustang and that dyno was accurate then I expect it to make about 390hp on the dynojet......so lies the magical 60hp that's missing. This isn't rocket science but the first places you look and the initial bases seem to have been covered.
What heads and intake do you have? We could quickly rule out power numbers depending on them. Is it definitely a DART block? Not that it has to be, but if it's not a dart block we can rethink everything you were told about the engine also. Any pictures of the engine bay? What clutch is in the car? Any noticeable smells?

Last edited by itstock; 10-25-2015 at 11:09 AM..
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  #23 (permalink)  
Old 08-18-2015, 05:43 AM
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Quote:
Originally Posted by DAVID GAGNARD View Post

Unless you go with a "modern" type engine,you will not have a smooth idling,banshee off idle engine, push rod,carbed, stroker motors just don't do that and make 585hp....


david
I am not sure that is completely true. A stroked 427/482 FE may not idle well but it will pull hard off idle. In a Cobra the tires will be spinning in any event. The HP/TQ is not peaky it is linear. I realize the OP has a Windsor but since he is gathering information that should be pointed out. A 585 HP 427/482 is very different than a 585 hp 351/427.

Good luck!
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  #24 (permalink)  
Old 08-18-2015, 06:04 AM
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ACE
look at Classic Cobra Pack mufflers 3" with the louvers turned to the engine. Measure your old muffler and see if you can install longer Cobra Packs.
When you install longer mufflers, they are quieter but allow more exhaust out.

My 354 / 302 stroker put made over 400 rwh - tq and I think a lot of it was my exhaust system.

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  #25 (permalink)  
Old 08-18-2015, 04:17 PM
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Originally Posted by Detroit Bill View Post
I am not sure that is completely true. A stroked 427/482 FE may not idle well but it will pull hard off idle. In a Cobra the tires will be spinning in any event. The HP/TQ is not peaky it is linear. I realize the OP has a Windsor but since he is gathering information that should be pointed out. A 585 HP 427/482 is very different than a 585 hp 351/427.

Good luck!
Bill:

I agree with you 100%,I was referring to a small block stroker making 585 hp.....A big block stroker making the same hp will be a lot "tamer" and streetable engine than the 427 small block stroker.......

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  #26 (permalink)  
Old 08-18-2015, 05:28 PM
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Quote:
Originally Posted by Ace23 View Post
......so lies the magical 60hp that's missing. This isn't rocket science but the first places you look and the initial bases seem to have been covered.
The bases aren't covered without a leakdown test. I would do a leakdown test on any motor I'm unfamiliar with just to know the general condition, problem or no problem.
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  #27 (permalink)  
Old 08-18-2015, 07:35 PM
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Originally Posted by scottj View Post
The bases aren't covered without a leakdown test. I would do a leakdown test on any motor I'm unfamiliar with just to know the general condition, problem or no problem.
Agreed. The other bases aren't rocket science either...
Spark, timing, fuel and exhaust. Really, if you have good hard parts what else is there?
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  #28 (permalink)  
Old 08-18-2015, 07:43 PM
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Originally Posted by itstock View Post
What heads and intake do you have? We could quickly rule out power numbers depending on them. Is it definitely a DART block? Not that it has to be, but if it's not a dart block we can rethink everything you were told about the engine also. Any pictures of the engine bay? What clutch is in the car? Any noticeable smells?

My nitrous is on a NOS progressive controller, single stage 50% initial at 4000rpms+wot with a 1.2 second ramp time (with the controller output cutting timing 6 degrees and also ramping the fuel pump to fully duty). I have had it on almost every single car that I have ever owned, including my 03 Cobra. The progressive controllers are absolutely awesome and so simple to use.
I am 100% positive it is a Dart block from looking it over when it was on a lift. The heads are Keith's Brodix platform......this was built in 2004 so not sure exactly what head they may have been using. The intake is a Victor Jr. Yes I have pictures on my phone I will just have to upload them. I have a receipt for the clutch that was put in at Olthoffs shop in 2010.......there doesn' appear to be any clutch slip and zero smells that would tip you off to the clutch burning.
Quote:
Originally Posted by Dwight View Post
ACE
look at Classic Cobra Pack mufflers 3" with the louvers turned to the engine. Measure your old muffler and see if you can install longer Cobra Packs.
When you install longer mufflers, they are quieter but allow more exhaust out.

My 354 / 302 stroker put made over 400 rwh - tq and I think a lot of it was my exhaust system.

Classic Chambered Exhaust Inc. - Cobra
I plan to pull a side pipe and have a look....take some measurements. It seems that firefly have good reports but you never know what you have until you confirm it. Based on many things being checkout I out it is very possible the side pipes could be a cause
Quote:
Originally Posted by scottj View Post
The bases aren't covered without a leakdown test. I would do a leakdown test on any motor I'm unfamiliar with just to know the general condition, problem or no problem.
Just one more thing I can add to my list of things to check.
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  #29 (permalink)  
Old 08-18-2015, 08:14 PM
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I agree a leakdown test should be done. Also the numbers for compression look to be low closer to 190.
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  #30 (permalink)  
Old 08-19-2015, 09:34 PM
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Figured I would follow up with some information from my records that came with the car. The superflo dyno sheets shows a max hp of 585 at 6100rpm and a max tq of 568 at 5000rpm.....the AFR ratio's are at 13:0 and climb to 14:3 at max rpm which was 7000. The only variances from the build sheet are that it listed a Davinci 950 carb and Performer RPM intake. The carb on the car now is a 750QF and intake is a victor jr. The camshaft that is listed is a Comp Cam .576 intake and exhaust gross lift with 252 exhaust and 262 intake with 112 lobe separation. I hope the camshaft isn't anything proprietary....this is from 10 years back and its stamped all over the build information so it doesn't appear top secret. I was aware the car did have a Davinci carb on it but that it was removed....I'm wondering if the intake manifold listed on the build sheet is a typo as I undertand it to have always had a victor jr on it. This is purely to provide information based on peoples questions about the motor....not to debate someone's dyno numbers and if they are accurate. With work being as busy as it is there has not been any time to start going down the checklist of to do items.

Last edited by Ace23; 08-19-2015 at 09:39 PM..
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  #31 (permalink)  
Old 08-21-2015, 03:03 PM
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Okay, I'm here to confirm Ace's concerns. We took our cars out yesterday evening and did a third gear roll-on and my car just pulled away. I then drove his car and in his words and I agree is a slug. No wonder he is talking big blocks and Coyote motors. His motor builds rpms slowly with no shock value. Not impressed at all! Our motors are similar builds with mine using a 4.1" stroke crank and his obviously a 4.0". We should have been neck and neck on our roll-on. When he gets back in town and he can drop the Cobra off I'm going to dive into this matter.......
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  #32 (permalink)  
Old 08-21-2015, 05:37 PM
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Ace, you can struggle with where the horsepower you have lost may have gone and you might even get your mileage up into the low teens. You will spend considerable time and monies to get fuel injection in the car and properly tuned. When you are done you might get to 450 RWHP

Imagine for a moment how your 03 Cobra would have felt if you could have taken 1500 lbs out of it. You had a Blown 4.6 w/a KB on it, right? Pretty impressive, right? Well you can do that with this car that is 3/4 ton lighter! You already said you don't care about the under hood originality so put in a blown 03/04 Cobra engine (it does have the right DNA).

As you already know from personal experience you will go from 300/350 RWHP to 600+ with lightening fast throttle response and 20+ mpg, but again this is not new ground for you — you have already been there. Remember that broad flat torque curve the engine had and the bottom end blast? I bet you miss that! Now put that in a 2300 lb car!

BTW if/when you do it, polish the valve covers. When you open the hood it will be wall to wall blown and injected Cobra — with the blower front and center! The visual is stunningly similar to the 427 SOHC powered cobras except this engine is way lighter and easily as powerful if not more so.


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Last edited by eschaider; 08-21-2015 at 05:53 PM.. Reason: Spelling & Grammar
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  #33 (permalink)  
Old 08-21-2015, 05:51 PM
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what air cleaner is on the motor?

what is your rear end ratio? Rear tire size?

What trannie?

Dwight
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  #34 (permalink)  
Old 08-21-2015, 07:07 PM
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Quote:
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what air cleaner is on the motor?

what is your rear end ratio? Rear tire size?

What trannie?

Dwight
Just one of those slim oval cobra setups. It's a paper filter and on the dyno the car made 4hp more with the filter removed. The rear end ratio is 3:23 with a TKO-600. Tires are Goodyear Eagle 315s in rear. In 3rd gear at 6000rpm Pman blew me off the road
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  #35 (permalink)  
Old 08-21-2015, 07:18 PM
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Seems that I would agree with above comments...

Compression
Leak-down
Pull valve covers and check everything in valve train
Fuel pressure?
Timing set up right when cam was installed? (Did they maybe index it wrong?)

Just trying to think of anything I can.

You have tall gearing, but that shouldn't do what you describe. I run 3:31 and have no problem. But then..I am running a big block 482.
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Old 08-21-2015, 08:03 PM
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Fuel pressure is on my list to check at idle and under acceleration on Ace's Cobra. My brothers hot rod truck had a fuel pump issue and experienced similar problems.
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  #37 (permalink)  
Old 08-22-2015, 04:45 AM
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252/262 @ .050"?

If that's duration at .050", that's a very large camshaft for a 427. My engines that are around this displacement and use hydraulic rollers have about 12-14 degrees less duration and peak at around 6000-6200.

My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large.

I'm thinking that if these are .050" duration numbers, the cam is so big that you have no bottom end and you can't run high enough in the rpm range where the cam wants to be efficient.

If those numbers are advertised duration numbers, then that would be a tow truck cam....

I'd change the cam....
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Last edited by blykins; 08-22-2015 at 04:49 AM..
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  #38 (permalink)  
Old 08-22-2015, 08:24 AM
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Quote:
My guess is that the cam has been changed sometime in the car's life and that cam does not match the rest of the engine/car/goals. Your compression test shows low because the cam is so large and the numbers actually jive for a cam that large
and the engine originally came with a dual plane intake and Davinci 950 carb.....now it has a Victor Jr. intake and another carb.....

Makes one wonder what else has been changed on the engine from the time it left the engine builder till now????????

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Old 08-22-2015, 10:22 AM
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Originally Posted by DAVID GAGNARD View Post
and the engine originally came with a dual plane intake and Davinci 950 carb.....now it has a Victor Jr. intake and another carb.....

Makes one wonder what else has been changed on the engine from the time it left the engine builder till now????????

David
If that current manifold is a single plane it will explain a lot of things as well, especially street performance. I'm with the folks comments above. Starting to suspect cam and intake...
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Old 08-22-2015, 10:27 AM
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On a big inch motor the single plane intake isn't an issue, but that cam is the root of all evil here....
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