Let’s see those 450-500whp acceleration videos

1AestheticCobra

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Hey guys,

so I just picked up a built supercharged 98 cobra with dyno sheets for 470whp. Long story short the thing feels nothing close to it. Put it on a scanner and it said the IMRCs are stuck so deleted them over the weekend. It does run a little cleaner, but still feels no where near this power level. The reason I’m so confident is it barely pulled on a stock LS car and my bolt on z28 would’ve smoked it at 80+. It will need a tune again due to the delete, but not sure it’ll make up for the size of power loss I am feeling. I just wanted to get an idea of how hard other guys are pulling in this similar HP range to show me I’m not crazy. Thanks.
 

jman37

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If you are making 470 and could barely pull on a stock LS car then there's something up. What gears are you running?
 

1AestheticCobra

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If you are making 470 and could barely pull on a stock LS car then there's something up. What gears are you running?

It does have stock gears I believe as it runs 70mph at about 2k-2.1k RPMs which I know could be a pretty big factor as well, but still feel like it should’ve demolished that car. Honestly feels like at 80+ it doesn’t pull near as hard as I thought. Top end feels doggish. I feel like this thing should be way less manageable. I’ve never driven anything with over 380whp either.
 

nomoretickets

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Gears are part of the equation here, but if it you have 470 wheel through a blower and barely pull on a stock LS, you got a real problem somewhere else.
 

1AestheticCobra

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Gears are part of the equation here, but if it you have 470 wheel through a blower and barely pull on a stock LS, you got a real problem somewhere else.

yeah absolutely. IMRCs being closed were part of the issue too I’m sure, but now they are deleted. Doesn’t feel any different, but will need another tune I’m sure. The guy only had a fuel pressure and boost gauge hooked up so hooking up my AFR gauge tomorrow hopefully to see what’s happening there.
 

Roots-type

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I don't have a vid to offer you, but something is way off. Last ls1 I ran was a 6spd trans am. Mods unknown, but I'm guessing it was stockish. From a 3rd gear roll (~50-100) I was at least 2 grey hounds out front. Repeated the run one more time further up the road and same result. Didnt even have to rev 3rd all the way out. If anything, if you're centri blown, it should feel sluggish down low not up top. Up top it ought to be screaming. Gears are definitely important for b head 4vs, but like mentioned above, it isn't what you're describing.
 

1AestheticCobra

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I don't have a vid to offer you, but something is way off. Last ls1 I ran was a 6spd trans am. Mods unknown, but I'm guessing it was stockish. From a 3rd gear roll (~50-100) I was at least 2 grey hounds out front. Repeated the run one more time further up the road and same result. Didnt even have to rev 3rd all the way out. If anything, if you're centri blown, it should feel sluggish down low not up top. Up top it ought to be screaming. Gears are definitely important for b head 4vs, but like mentioned above, it isn't what you're describing.

So do you think I should take it a tuner and have them decipher what could be going on? I don’t know if this is something a tuner would pick up quickly in the midst of their tuning process or not. And don’t get me wrong the car pulls smooth and pretty hard, but no where to what I figured a 470 to the tire car would feel like..
 

Roots-type

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So do you think I should take it a tuner and have them decipher what could be going on? I don’t know if this is something a tuner would pick up quickly in the midst of their tuning process or not. And don’t get me wrong the car pulls smooth and pretty hard, but no where to what I figured a 470 to the tire car would feel like..
If it was my car, I would get an appt with the best shop around and have them dial it in on the dyno. Take the time to prep beforehand. New tr6 plugs gapped ~ .030 and a new fuel filter. If it's running pig rich, you may get to the shop early and change the plugs in the parking lot so not to take a chance of ruining them. Make sure the air filter is up to snuff also and the maf sensor has been cleaned with approved maf sensor cleaner.

Have you pulled a plug yet to see what's up?
 

1AestheticCobra

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What's the setup of the car?

I would be ok with that. Lol

vortech v-1 on 10lbs. Attached pictures for build list although doesn’t give specifics on internals and stuff.

upload_2020-6-26_15-9-20.jpeg
upload_2020-6-26_15-9-38.jpeg
 

1AestheticCobra

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If it was my car, I would get an appt with the best shop around and have them dial it in on the dyno. Take the time to prep beforehand. New tr6 plugs gapped ~ .030 and a new fuel filter. If it's running pig rich, you may get to the shop early and change the plugs in the parking lot so not to take a chance of ruining them. Make sure the air filter is up to snuff also and the maf sensor has been cleaned with approved maf sensor cleaner.

Have you pulled a plug yet to see what's up?

makes sense and I have not. I plan on pulling a plug tonight.
 

98 Saleen Cobra

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I would be ok with that. Lol

vortech v-1 on 10lbs. Attached pictures for build list although doesn’t give specifics on internals and stuff.

View attachment 1648715View attachment 1648716

well I can tell you you’re not making 470 on a low compression engine. And 10psi on a v1 s trim. Not to mention if they put 03/04 cobra cams in it. What type of cooler do you have for the blower
 

1AestheticCobra

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well I can tell you you’re not making 470 on a low compression engine. And 10psi on a v1 s trim. Not to mention if they put 03/04 cobra cams in it. What type of cooler do you have for the blower

There is no intercooler setup and I’d have to check for aftercooler. The guy provided the dyno sheets, but sounds like something has most definitely changed since then.
 
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98 Saleen Cobra

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There is no intercooler setup and I’d have to check for aftercooler. The guy provided the dyno sheets, but sounds like something has most definitely changed since then.

you’d know if you had either. Either a air to air. Or a air to water from vortech.
 

nomoretickets

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You should absolutely get it to a tunner. Something is way off, and at this point any attempts to fix it would just be taking shots in the dark. Plus, you deleted the IMRCs, which absolutely needs a retune. Pull your plugs, replace em if that doesn't show an obvious problem, then fuel filter, clean your air filter, check for vacuum leaks, etc. and once you have the basic maintenance take. Care of, get it to the tunner.
 

98SVTContour98

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get a dyno tune!!!!!

My IMRCs were stuck...I deleted them and the car was still way down on power....a dyno tune fixed the issue.
 

Adower

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Hey guys,

so I just picked up a built supercharged 98 cobra with dyno sheets for 470whp. Long story short the thing feels nothing close to it. Put it on a scanner and it said the IMRCs are stuck so deleted them over the weekend. It does run a little cleaner, but still feels no where near this power level. The reason I’m so confident is it barely pulled on a stock LS car and my bolt on z28 would’ve smoked it at 80+. It will need a tune again due to the delete, but not sure it’ll make up for the size of power loss I am feeling. I just wanted to get an idea of how hard other guys are pulling in this similar HP range to show me I’m not crazy. Thanks.

I make around ~460 and the car does not feel like it’s really going anywhere until you get into the upper rpm with a centri blower. I would say my car really starts to pull around 3500rpm and up.
 

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