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View Full Version : No high speed in these cars I guess


Dave B.
04-02-2006, 10:26 PM
I was on the interstate today and down shifted to 5th gear to run a Turbo VW of some kind, well I pulled away from him of course but soon as I shifted to 6th I got huge knocking and had to back off, i thought I was just tuned too lean yet Sam says thats not the case, that every one of these that blow up are trying to run at top speed for a period of time, high HP high boost for top end top speed runs, he says these cars simply cannot take bogging in top gears no matter how its set up, what say you?

RF Cobra
04-02-2006, 11:44 PM
Depends on what you consider high speed I guess. An '03 ran 203 mph on the salt that was putting out 614 hp and 612 lb-ft torque at the rear wheels. :flash:

I know 6th will reduce your top speed with stock gears, don't know if the 4.10s are enough to make 6th usable for you at high speed.

RedfireSVT
04-03-2006, 01:10 AM
High speed runs can and do damage these engines. But by high speed I mean up to 160mph or somewhere close to that speed. It usually takes multiple runs to cause damage but every motor is different. Personally I avoid anything over 130mph. And I can't tell you the last time I did even that.

Dave B.
04-03-2006, 01:28 AM
why do you figure this a problem? does not make sence to me, I understand the bogging under high boost, but so long as the speed is creeped up on slowly using a low boost as possible, I would think it would be OK, but its not,
So why can a Porche do it and these engines not? how can a Mercedes do it and these engines not? I think a Corvette can do it without blowing up,,,,,
whats the deal mang????

ausie
04-03-2006, 08:16 AM
I did not have any issues burring the needle last year in excess of 160, then of course I was not in 6th gear either. Both the rear gears and forced induction are still stock on my car. I am sure most know that higher gear ratios in the rear will reduce the top end. Typically at the salt flats, they use a lower gear ratio, otherwise the top speed will be much lower than it can be. If you want to go over 175mph swap out the gears for 3.27 or lower since the stock 3.55 or aftermarket 4.10 or 4.30 may be too big. Also since the valve train is different than the 01 (different cams to make use of the forced induction) the maximum RPM would probably cause valve float if pushed to the 7000 rpm mark that the 99/01 were capable of. As for the Porsche, it was designed for maximum speed for use on the Autobann and in some cases they validate the top speed at 220 or above and I think it has a max of 9000RPM (depending on model) as well as some almost being 800lbs less in mass. And I highly doubt that the boost level from the turbo trim is higher than 10 psi. How many times do you find yourself pushing the car beyond 150? As it is with any vehicle, there will be a maximum amount of speed it will take before parts fail (bearings, drive shaft, valve train, etc...).

SuperG
04-03-2006, 08:17 AM
That does not sound right...no matter how fast you are going, be it 30, 90, or 160+, the engine is still turning at high rpm's in a certain gear be it 1st, 3rd, or 6th. Afterall, the Cobra is not the only car in the world with this engine and we don't hear about high speed problems with them...

RedfireSVT
04-03-2006, 09:32 AM
why do you figure this a problem? does not make sence to me, I understand the bogging under high boost, but so long as the speed is creeped up on slowly using a low boost as possible, I would think it would be OK, but its not,
So why can a Porche do it and these engines not? how can a Mercedes do it and these engines not? I think a Corvette can do it without blowing up,,,,,
whats the deal mang????The deal is the piston to wall clearance. It's too tight which builds excessive heat which is what causes these motors to let go. As much as I love these cars I wouldn't compare the Cobra motor to a Porsche or Mercedes. A blast up to 160 puts more strain on the motor and builds more heat than just flogging on it around town, which can also fry these things. They aren't bulletproof and I personally believe they are flawed.

beerkat
04-03-2006, 09:37 AM
Most of us do not run high rpm (5500+) for very long in the lower gears. Reading what has been posted makes me think that when running high rpm's for a sustain period of time is when the engine starts to fail.

When doing a road course I might run 5,000 rmp, but that is only for less than 30 seconds at a time.

blk04cobra1
04-03-2006, 09:59 AM
The deal is the piston to wall clearance. It's too tight which builds excessive heat which is what causes these motors to let go. As much as I love these cars I wouldn't compare the Cobra motor to a Porsche or Mercedes. A blast up to 160 puts more strain on the motor and builds more heat than just flogging on it around town, which can also fry these things. They aren't bulletproof and I personally believe they are flawed.
You pretty much hit it dead nuts on...when you do multiple back to back high speed runs, it creates a ton of heat, which has been known to warp the pistons causing failures...It's not that the car wont do it, its just not recommended to do it back to back...I personally dont see the point of taking a race over 140mph, especially on the street...you have to look at your gearing as well...you pretty much run out of gear around 130mph with those 4.10's :thumbsup:

QIK1320
04-03-2006, 03:08 PM
I work for Porsche, the same deal applies to them when you're performing mods, especially when you're upping the boost...a 996 tt can handle 1 bar for a long period of time on the high end, but Porsche really over does there intercoolers in terms of size. Anything above that and I would not feel comfortable loading it for too long on the high end.

I used to own a 1987 930 before coming over to the mustang and that car ran 11.50's in the 1/4 with roughly 13 psi, but I never had the guts to stay in it for to long on the highway.

Linn@Amazon
04-03-2006, 04:27 PM
these cars will not hold up to sustained high speed runs...your 410s are hurting your top end...if you take nothing else away from this post....please listen to these guys about this..it is not open to debate...no matter how well tuned it is..do sustained high speed runs like that and you will be putting a new motor in your car

Dave B.
04-03-2006, 05:43 PM
I guess it would be ok to go high speed so long as its creeped up on??
the stock engine does what? 8psi? I would think so long as the boost durring accelleration is kept low, then speed could be built up? am I right?

Linn@Amazon
04-03-2006, 06:14 PM
sustained high speed runs=:bawling: it doesnt matter how you get up there

03 cobra toy
04-03-2006, 07:04 PM
I guess my car is a factory freak.... My car was clocked at 169 mph @ The Texas Mile. I have run my car at least fifteen times with some runs back to back. No problems here :D

It's all in the tune! :thumbsup:

Stock engine
355 gear
2.93 upper
466 rwhp/rwtq (sae)


169 mph was in 5th gear 6K rpm

http://www.texasmile.com/October2004OfficialResults.asp

cobrabitn
04-03-2006, 07:34 PM
David, I don't think your car is a factory freak...I think it freaks out when you drive it.... :rotf:

RedfireSVT
04-03-2006, 08:44 PM
I guess my car is a factory freak.... My car was clocked at 169 mph @ The Texas Mile. I have run my car at least fifteen times with some runs back to back. No problems here :D

It's all in the tune! :thumbsup:

Stock engine
355 gear
2.93 upper
466 rwhp/rwtq (sae)


169 mph was in 5th gear 6K rpm

http://www.texasmile.com/October2004OfficialResults.aspNo one ever said the car can't do it, just that you shouldn't do it. Every car is different and some last longer than others. But with that kind of abuse sooner or later it will let go.

Dave B.
04-03-2006, 09:06 PM
its most likley this, the stock cobra is probably safe or maybe with a pulley, and 3:55 gears, but soon as we start cranking on DA BOOST as well as other stuff, I bet we gain more for the short run and lessen the engines ability to take the long hard run

mkkrs1
04-03-2006, 09:59 PM
so how fast were you going when it started detonating. If you wanted a top speed car maybe you should look else where.

Ram77mus
04-03-2006, 11:35 PM
Any supercharger or forced induction application causes lot's of heat when running them hard for a long period of time. The cooling setup on the 03-04 cobra's don't hold up to the heat they create.

Dave B.
04-04-2006, 12:29 AM
so I come back to the question of the water/meth injection system?
would that water/meth not cool the charge down enough to stop it?
would it not cool the heck out of the air?

Firme
04-04-2006, 02:06 AM
so I come back to the question of the water/meth injection system?
would that water/meth not cool the charge down enough to stop it?
would it not cool the heck out of the air?

Rob is right on the money...

David (03 Cobra Toy) is going to kill me for draggin him more into this. But he tackled the cooling issues of the 03's way back when he first got it, when most people weren't worried even looking into it, and wondering why their motors were letting go. And he has been improving upon it ever since. He not only does the Texas Mile runs @ 169 mph, but his car has seen many many many Open track events with long run sessions, and in the Texas heat. Texas world speedway has a 145mph-160mph front straight. He has approached his setup knowledgably.

Boils down to this. Its first and foremost in the tune. If you got the tune right (As big as Houston is, with as many shops, there would only be two shops I would let tune my car) , after modding past a moderate point, heat comes into play, and you must tackle cooling issues, engine, as well as air charge. At that point the piston to wall clearance will trump you. If you are serious about getting a top end runner, look into a rebuild down the road, with better pistons and correct wall clearance, and it will open up the cars potentials greatly. Rebuilding a mod motor is not as big an ordeal as some people make it out to be as long as you have a trustworthy shop. :)

Dave B.
04-04-2006, 02:27 AM
I understand that, for sure, but my wide band goes at its leanest to about 11.3 it starts a little leaner than that before about 4 Lbs boost then it richens up, but before Sam tuned it I was running real real rich and I still could get knocking under those high speed pull conditions, so when Sam told me that even if he made it as righ as 9.1 A/F it would still knock under the long hard pull, so the only thing I can think of for a short term is to cool the pressurized air, thus possibly a water/meth kit,,,when water s sprayed in Atomized form it evaporates like right now, and releases coolness, this should help, the other thing im worried about is im supposed to get a lower,pumps,and new tune done soon but thats going to make even more heat is it not? how the heck do you guys with 16 Lbs boost with ported Eatons, keeping from detonation?

RedfireSVT
04-04-2006, 09:17 AM
If you want to run that much boost buy a Whipple.

blk04cobra1
04-04-2006, 09:53 AM
so I come back to the question of the water/meth injection system?
would that water/meth not cool the charge down enough to stop it?
would it not cool the heck out of the air?
When water/meth injection works, it works...problem we found is that we couldnt get it to be consistent...only thing we've found to work so far is the h/e, radiator and external water pump with an ice mix...not saying there arent other options (evans, ldc, etc)

Dave B.
04-04-2006, 02:28 PM
Man I was already to buy a Whipple but was talked out of it because unless I was going to run 20 Lbs of boost change fuel lines and whole nine yards, a ported Eaton would do about as well, DAM I wish there was some consistancy on this board

Linn@Amazon
04-04-2006, 02:59 PM
:eek: ...Whipples Rock...;)

Firme
04-04-2006, 04:20 PM
Man I was already to buy a Whipple but was talked out of it because unless I was going to run 20 Lbs of boost change fuel lines and whole nine yards, a ported Eaton would do about as well, DAM I wish there was some consistancy on this board

a ported Eaton is good for saving money, getting good numbers, and improving 1/4 goals. Did you specify you wanted to do high end runs and bring down the air temp, because that would definitely sway the whipple more than the eaton, even at low boost. It can be frustrating as there is a lot of trial and error and a matter of what questions are asked.

RedfireSVT
04-04-2006, 05:10 PM
[QUOTE=Dave B.]Man I was already to buy a Whipple but was talked out of it because unless I was going to run 20 Lbs of boost change fuel lines and whole nine yards, a ported Eaton would do about as well, DAM I wish there was some consistancy on this board[/Q


That's just not true. A Whipple needs only the same supporting mods as a ported "Heaton", is way more efficient at any level of boost, runs cooler and will smack a ported blower upside the head! Ported blowers make nice dyno numbers but suffer from heat soak. A Whipple is far superior just more expensive.

Big Daddy
04-04-2006, 05:20 PM
Granted I do not own a 2003 or 2004 Cobra just my little ole 2001. It does however put out 17psi of boost from a Vortech T-trim. The combination that I found has worked best for my setup is an aftercooler and the Snow Boost Cooler, even on hot days after repeated high speed runs my intake temps are less than 100*. With this setup I have NEVER had detonation. If it was my car I would upgrade the intercooler and get the Snow Boost Cooling system. BE SAFE NOT SORRY! :thumbsup:







PS this is my third engine, I do know what I'm talking about NOW! :eek:

Firme
04-04-2006, 05:32 PM
PS this is my third engine, I do know what I'm talking about NOW! :eek:

Gregg, did you go with a whole new block on the rebuilds (after the first rebuild, assuming you did not hurt the block and that you maxed the .020 over on the first rebuild)? or have you gotten the stock block re-sleaved?

Dave B.
04-05-2006, 01:01 AM
say big daddy, I have wanted to talk to someone who has a Snow kit, can you tell me what differance you notice when its on vs off?
in what way do you notice what it does?

Big Daddy
04-05-2006, 08:59 AM
Gregg, did you go with a whole new block on the rebuilds (after the first rebuild, assuming you did not hurt the block and that you maxed the .020 over on the first rebuild)? or have you gotten the stock block re-sleaved?

The first engine loss was due to hydro lock and I blew a hole in the block so I had to get a new block. Then the second block was put in stock with forged rods and pistons but was tuned incorrectly and I lost number 8 cyl. The third rebuild the block was bored .020 over. So my block is really a 98 block bored .020. :thumbsup:

Big Daddy
04-05-2006, 09:04 AM
say big daddy, I have wanted to talk to someone who has a Snow kit, can you tell me what differance you notice when its on vs off?
in what way do you notice what it does?

NONE. I have the system set to come on when I hit 5lbs of boost, it really is just keeping the intake temps cool. This helps prevent detonation and adds some hp but not enough to be noticable. I have seen on a dyno an '03 gain 30rwhp from the system but I don't know how it was tuned and if they were using a 50/50 mix of water/meth or a different mix.

Dave B.
04-05-2006, 02:49 PM
do you notice when its on or off? Or do you notice less detonation? is it worth putting one on?

bbrence
04-11-2006, 03:23 PM
Hey folks! It's not vehicle speed that matters......it's engine speed, aka RPM! Sustained high RPM [above the redline] will eventually cause damage to any production engine.....Porsche, Corvette, etc included! The Cobra engine is extremely solid.....within it's design limits! With all due respect, there are too many backyard mechanic's looking for cheap bolt-on horsepower, without a clue what they are doing. More horsepower = Less reliability There ain't no free lunch!!!

Dave B.
04-11-2006, 03:29 PM
I have spoken with the MAN on this issue, not RPM sir,,,,,,,
its boost over 5 Lbs under bogging conditions

Big Daddy
04-11-2006, 03:44 PM
do you notice when its on or off? NO Or do you notice less detonation? NOis it worth putting one on?YES

I would say anything that reduces the intake temp is a good thing. It gives protection more so than HP.

RedfireSVT
04-11-2006, 10:58 PM
The problem with high speed runs is the increased load placed on the enigne. The faster you go the more air resistance the engine has to overcome. So technically car speed DOES have an effect. I don't care to debate, do what you want and believe what you want. It is MY personal opinion that high speed runs to 160 are at the very least not good for these engines.

ausie
04-12-2006, 08:13 AM
The problem with high speed runs is the increased load placed on the enigne. The faster you go the more air resistance the engine has to overcome. So technically car speed DOES have an effect. I don't care to debate, do what you want and believe what you want. It is MY personal opinion that high speed runs to 160 are at the very least not good for these engines.
I would have to agree with RedfireSVT :thumbsup: . Considering the forces applied on the contours of the vehicle can be excessive at high speed and add that to head winds and it would more than likely increase more than one would reailze.

No matter how you drive there will be wear and tear on the motor. Proper maintanance and minimized abluse will make the motor and vehicle last much longer. Also the faster you go the more risk is involved. Even though each response may be different in this thread, they do have some merit. :thumbsup:

Knowing the limitations of your vehicle will keep you firmly on the black and out of the red (which tends to be a messy clean up for the emergency response team). A friend of mine would always tell me "shiney side up"