rsilver

I posted this on the exhaust board with no response but thought I would try here. I just installed
SLP 1 5/8 headers a 3 inch catco cat and
a 3" Flowmaster muffler. I lost a TON of torque from off idle to about 3,000 rpm but the motor difinitly does pull better from 3,000 clear up to 5,000 rpm. I know its a trade off,I have done this before on other vehicles, but have never experienced this much low end loss.Is there anything I can do to
get some of the low end back? My old muffler was a flowmaster 2 1/2 inch and it sounded great, but this 3" is f#$%in loud especially since I gotta take it to 4,000 rpm just to get going. I was wondering if I should try a quieter more restrictive cheapo muffler to see if I can get some torque back.Or maybe there is a trick way to tune the exhaust flow somehow . Maybe I have just finally gone nuts, but what do you guys think??
Sure appreciate the help.....bob

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91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

Mkos1980

iTrader: (8)

i had the same problem. I ran a 14.6 @93 with stock manifolds cat and 3in edelbrock catback. When I put my 1 5/8 TES and 3in Catco I ran 14.7@ 96 With the old setup my 60 was 2.0 and Headers were 2.25 But recenly i bumped up my timing and ported my plenum (open element for you) and ran a 14.2@98 I think everything is cool with your car, but you have to get more air in it.

GOFASTER

You will loose low end power, if you have not had alot of mods done to your car. If you just install headers, and not much else (i.e., cam, heads, AFPR, NOS, ect....) you will get more horse power, but loose some low end torque.

Just keep moding, headers are great

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25th Anniversary Z28

Mkos1980

iTrader: (8)

Oh Also i added a AFPR That might help you too. You may have too much air(as i seen you have all the TBI mode) and a full exhaust and not enough fuel. This is what i'm thinking. Somebody else will probebly have a better idea.

theformula

What intake mods have you done?
Looks like you've already got a good flowing exhaust. Work on your intake and a cam. I recommend 08-304-08. Theres also a crane cam that is MADE for TBI. Give me an email and I'll tell you more about it.

I know your probably tired of hearing this, but if want a really impressive bump in performance get TPI components (manifold, plenum, runners, throttle body, ECM, harness (roughly $250 for harness). I have a friend with all these components for sale right now.

If it's not an option, then open up your intake. Sorry I couldn't be more help, I'm not too familiar with TBI.

The cam will make a huge difference.

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'92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,Crane AFPR (42psi),MSD6AL,homemade cold air,K&Ns,3:73s,JET fan switch, Macewen white face gauges...ZZ9 cam (i still have to install it )

[This message has been edited by theformula (edited November 16, 2000).]

Godti

How much your friend selling the TPI for?? Where are you located?>?

rsilver

MKOS80, you may have a point on being lean. When I first tested the car I didn't notice torque loss as much. After a short time
the torque loss was much more noticable.
I wonder if the computer leaned me out or
made some other adjustment.Is that possible? I am gonna check things with my friends scan tool.

Theformula, the only mods are the ultimate TBI mods. Everything else is stock.
I don't have the time or ability to convert to TPI but thanks anyway.
I am gonna add an intake and bored TBI next
when I get some money. For now, I just gotta
make the car more drivable.

Any other thoughts and suggestions are appreciated. Thanks........bob

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91 camaro RS L03 convert,
t-5, ultimate TBI mods,TBI spacer,SLP 1 5/8 headers,
3"cat back, 3.42 torsen posi,alston SFC's,Global West LCA relocation brackets

Box of Rocks

Silver,

When you installed headers, you increased the exhaust systems' ability to scavenge gasses from ye old cylinder after combustion.

Header installation on a carbed car requires richening the mixture, so I presume your car is no different. Try an AFPR and goose the FP up. That small primary pipe should help bottom end torque, not hurt it. Also, play with timing, like....uh....set your initial advance to 8-10 degrees before TDC. Shoot for 34-38* advance, all in by 3,000 RPM.

Let us know how this goes. Good luck.

BOR

five7kid

iTrader: (14)

I wouldn't necessarily call 1-5/8" primaries on a 305 "small". I know that's what SLP recommends, but I've seen 1-1/2" primaries on a truck 350 do wonders for torque over the stock manifolds. I'm seriously considering 1-1/2" primaries for my pepped up 305.

Unless you're really turning some r's or have TPI, 1-5/8's are probably too big for a 305. But, you should be able to recover some of the lost torque with the suggestions made above (although your induction mods may take you the other way).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.73 unlimited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.