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losing power? help

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Old Sep 27, 2011 | 01:08 PM
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Default losing power? help

Well I will say some if it might be in my head lol but it seems that my top end power is not what it used to be. I make around 430 whp on a Mustang Dyno currently but on the street it and track it doesnt seem to MPH like it used to.

I suspect may by after a few hard shifts into the higher gears maybe my 118k 98 stock lifters are not doing there job. My car pulls good in the mid range and seem to take alot of cars from dig w more or same power than me but seem to run me down at over 100 mph


My combo is a veg fast 92 90 hc 346 11.2 comp 228 232 595 574 114 lsa w a M6 3.42 gears

I do get a bit of blow by but who doesnt w a higher milage ls engine lol

Any thoughts would be greatly appreciated.

Cheers
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Old Sep 27, 2011 | 02:06 PM
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What is your MPH at the track? Where do you live? Hot climate? What clutch are you running? Last time you checked or swapped springs?

I went from 372 to 436 rwhp and I got used to the power in literally one day and the car felt slow already. I would put money on you just being used to it. Some people are more sensitive than others to it

Last edited by mchicia1; Sep 27, 2011 at 02:08 PM.
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Old Sep 27, 2011 | 02:28 PM
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Well my mph on a hot day w 4500 da is around 118 and 120 ish on a good day. I just talked to Chad at Partriot where I bought my heads and we have decided to swap springs since w my cam I should see about 15k out of them and now have about 40 k on them. I should have done it last year when I did the guide seals lol. 4-5 hr job at most taking my time.

SHould do it either way w the FI going on this year
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Old Sep 27, 2011 | 02:29 PM
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Originally Posted by fotoboy
Well my mph on a hot day w 4500 da is around 118 and 120 ish on a good day. I just talked to Chad at Partriot where I bought my heads and we have decided to swap springs since w my cam I should see about 15k out of them and now have about 40 k on them. I should have done it last year when I did the guide seals lol. 4-5 hr job at most taking my time.

SHould do it either way w the FI going on this year
um 40k on the springs...that is your problem then. Definitely time to do them...
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Old Sep 27, 2011 | 02:47 PM
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I agree it sounds like the valve springs in need of replacement with that kind of mileage on what appear to be XER lobes. Another thing that came to mind though as you mentioned it happens worse at higher speed meaning more drag is the clutch is possibly slipping.
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Old Sep 28, 2011 | 01:40 AM
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Originally Posted by PRE-Z06
I agree it sounds like the valve springs in need of replacement with that kind of mileage on what appear to be XER lobes. Another thing that came to mind though as you mentioned it happens worse at higher speed meaning more drag is the clutch is possibly slipping.
Not the clutch, it's a puck style and when it starts slipping it's just gonna go.
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