performance gains from catless ypipe
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Joined: Apr 2002
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From: Hockessin DE
performance gains from catless ypipe
im finally going to replace the front ypipe with Mid America's stainless steel 2.5" peice. ive gotten my E/T down to 13.4 at 102.5 with the light mods listed in my sig and was wondering how much i can expect to gain by removing the precats. ive read that the front ypipe with precats was one of the most restrictive components in the L98 design, so this mod should reap a considerable gain (two tenths or so). can anyone give any feedback with E/T or hp #s with this mod? thanks
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Re: performance gains from catless ypipe (tpivette89)
The front Y isnt as bad as the manifolds themselves. But it should give something around 10hp.
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From: SE NY
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Re: performance gains from catless ypipe (tpivette89)
I gained 23hp (i.e. 2.3mph in trap speed) from doing the TPIS cat-back, RT cat and custom 2 1/2" front Y. That's based on trap speed increase with data corrected for weather conditions.
Vic'89 did his TPIS cat back after the front Y and cat and gained, I believe, 10-15hp.
I think both front & rear Ys are restrictive so the one you replace last will show the most gain.
So my estimate is that you should gain at least 10hp, maybe more. Compare your new trap speed with prior to get HP increase.
You can add 10hp by tossing the "frisbee" from the front of your water pump pulley and another 8-10hp by cutting back your spark plug ground electrodes (method on my site).
Add a 160 deg stat and aux fan sw to gain another 10hp over stock, providing air temp isn't in the 90s, though this may be included in your other mods.
Remove your spare and jack for a nice 45lb loss or about 5-6hp gain.
After the front Y, you might want to have your shift points raised if below 5,000rpm.
BTW, that's a pretty good short time, are you running stock TC, tranny and 2.59s or have you done some tranny work? I couldn't pull those times till I had a 2,000rpm TC installed.
[Modified by 65Z01, 9:27 PM 7/31/2002]
Vic'89 did his TPIS cat back after the front Y and cat and gained, I believe, 10-15hp.
I think both front & rear Ys are restrictive so the one you replace last will show the most gain.
So my estimate is that you should gain at least 10hp, maybe more. Compare your new trap speed with prior to get HP increase.
You can add 10hp by tossing the "frisbee" from the front of your water pump pulley and another 8-10hp by cutting back your spark plug ground electrodes (method on my site).
Add a 160 deg stat and aux fan sw to gain another 10hp over stock, providing air temp isn't in the 90s, though this may be included in your other mods.
Remove your spare and jack for a nice 45lb loss or about 5-6hp gain.
After the front Y, you might want to have your shift points raised if below 5,000rpm.
BTW, that's a pretty good short time, are you running stock TC, tranny and 2.59s or have you done some tranny work? I couldn't pull those times till I had a 2,000rpm TC installed.
[Modified by 65Z01, 9:27 PM 7/31/2002]
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Joined: Apr 2002
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From: Hockessin DE
Re: performance gains from catless ypipe (65Z01)
to be more specific with my "free mods" i have :
- cut filter lid
- ported plenum
- removed frisbee
- 160* stat
- upgraded ESC module
i have also removed my jack and spare and usually run with about a 1/4 tank of gas. my fuel pressure is set at 48psi with the vac hose disconnected and i run the base 6* timing. im running the stock converter and have Michelin Pilots which have been hooking excellently with 20psi in them. i also have the 3.07 rear gear option, so im a little stonger out of the hole and in the top end. looking for 13.2s with the front ypipe swap and cooler weather, then ill be digging into my manifold base hoping for the 12s. i think my car has responded really well to the small amount of work that it has done. ive got less than $600 invested in go fast parts, and by the looks of things, ill be hitting 12s for less than $1000. not too shabby for an old L98
[Modified by tpivette89, 6:18 AM 8/1/2002]
- cut filter lid
- ported plenum
- removed frisbee
- 160* stat
- upgraded ESC module
i have also removed my jack and spare and usually run with about a 1/4 tank of gas. my fuel pressure is set at 48psi with the vac hose disconnected and i run the base 6* timing. im running the stock converter and have Michelin Pilots which have been hooking excellently with 20psi in them. i also have the 3.07 rear gear option, so im a little stonger out of the hole and in the top end. looking for 13.2s with the front ypipe swap and cooler weather, then ill be digging into my manifold base hoping for the 12s. i think my car has responded really well to the small amount of work that it has done. ive got less than $600 invested in go fast parts, and by the looks of things, ill be hitting 12s for less than $1000. not too shabby for an old L98
[Modified by tpivette89, 6:18 AM 8/1/2002]
