i bet i get me some after reading this..... :yesnod: :yesnod: :cool:


[Modified by mikes84vette, 3:56 PM 12/27/2001]

 

Another argument is that you need some sort of restriction for shut-down. Without it, cold air just gets sucked right in and can warp the valves.

It doesn't have to big, just enough to warm the air while the valves cool off. On my motorcycle I have a little teeny tiny baffle, and on the car I have the cat. Its amazing how much difference 6 more cylinders make, the Car is just as loud as the motorcycle. :eek:

 

I did mine about a month ago. Didn't notice a difference in power and sounds great :D

 

Don't have exactly what you want. I have an iron headed b-body LT1 with all the bolt on mods (intake, 1.6 rockers, headers + drive train mods including suspension/trans/drag radials) and stock b-body cam. I switched from a Borla exhaust system (2.25") to a 2.5" custom exhaust. Added 3 mph in the 1/4 mile (93mph to 96 mph) and cut 0.44 seconds from my 0-60 time (6.12 seconds to 5.68). Not a bone stock y-body LT1 like you asked for, but close. If restriction in my exhaust made more torque go up, I'd expect a faster 0-60 time with the Borla....

Just my experience,
Eric

 

We've got a dyno day coming up in a month or so... I'll see if there's anyway I can do a comparision test with and without the mufflers (otherwise 100%stock LT-1), then we'll know for sure! :)

:cheers:

 

Well...I put them on yesterday and.....umm.....well...... I LOVE THEM! The car sounds MEAN. I didn't feel a decrease in torque...I actually felt an increase in acceleration! ALOT more top end also. It isn't my imagination...it really did give it more pickup. It is one great mod! :cheers:




[Modified by fade_to_black, 10:38 PM 12/29/2001]

 

2 points I'd like to chime in on here.

#1. Your cam profile doesnt require backpressure. It's not the loss of backpressure that hurts you...losing backpressure allways helps. Its the scavenging effects. Duration, cam profile and timing all play a key role. If you have too much scavenging effects it can actually pull some unspent fuel/air out of the cylinder at various rpms resulting in a loss of power. Some cam profiles have overlap in them between the exhaust valve opening and the intake valve opening at the same time in between firing. Imagine hooking up a huge vaccumm cleaner to your exhaust system and actually pulling a vaccumm on your entire exhaust system with the car running. As the exhaust valve opens to expel the spent fuel/air, it will be sucked out. Sounds great right? Not if at the end of its opening duration there is some overlap and the intake valve is opening up just a little while the exhaust valve is still open. Some of the good air/fuel will get sucked out too. In a roundabout way your cam profile may dictate that you do "need" some backpressure but only to prevent some of the unspent fuel/air from escaping. The timing is that critical, but this is only in exstreme cases where the exhaust system is very far from stock. ie: longtubes, x pipe, no mufflers. X-pipes have proven to be so good at scavanging in some cases that some people did indeed lose some but its very rare. I suspect that Mr Mojo knows his car and its capabilities better than anyone (you da man Frank ;) ) but if he did lose power it may be that his car is picking up some false spark knock from the extra noise (I've seen it happen)

#2 Silver and Red CE is correct that if you have the stock manifolds and cats you wont lose anything. For example, lets take my car. I went from having the stock exhaust system in and dynoed at 216 rwhp and 320ish rwtrq. I then had a local shop put in true 2.5 inch pipes all the way from the collectors to the mufflers and removed the main cat as well as the precats. Talk about a reduction in BP :yesnod: I then re-dynoed the car. Surprise surprise...I gained alot of torque DOWN LOW and HP ALL THROUGHOUT THE ENTIRE RPM RANGE!!! With no loss of any power anywhere. I know its an L-98 and not an LT-1 and the cam profiles are vastly different but the same theory applies as the L-98's intake and cam make for tremendous cylinder filling (lots of air velocity) at lower rpms hence the abundance of low end grunt. I have yet to dyno since having the muffler elims and H-pipe installed but the car did pick up a couple of mph at the drag races after I did those two mods. Last dyno numbers were 250rwhp, 350rwtrq. My trap speeds would seem to indicate a good deal more than that now. At the cruise in I beat alot of stock and mildly modded LT-1 cars and my trap speeds were higher than alot of them by 2 or 3 mph. I'm not bagging on anyone or anyones cars either so please dont take offense. It's just on that particular day, in those conditions thats what happened and it wouldnt be fair to compare what the same cars could do at different tracks on different days under different conditions.

 

I've never been convicted of being the sharpest tool in the shed but I can't figure this out:

Muffler Eliminators are bad because they reduce backpressure.

(Insert assumption here that the backpressure reduction is due to increased flow)

Corsa, Borla and the other ~ 1000.00 exhaust systems claim flow increases of ~ 40%. 40% would seem to be even more of an increase than with elims.

So is one type of backpressure reduction that much different from another?

I'm talking here about cars with cast iron manifolds and catalytic converters. It would seem the manifolds and converters create the majority of the backpressure.

Not saying anyone is wrong - I just don't understand how one method of reduction makes power while another loses power.'

Mark

 

I just had it done to mine this weekend, and I can't notice a difference at all. I imagine if I went to the track a lot and had some numbers to look at I could "notice" a difference. But I just drive for fun, and boy is it fun to just rumble down the street!!!

This is by far the best "bang for your buck" mod out there, IMHO

 

eliminators are ausome. you can hear the growl befor you see tha car..

 

The wife, the kids and my neighbors know I am on my way home. :D

Glad you like 'em, I do.

 

Talk about it! Everybody is looking to see where it is coming from. It's fun to watch there expression change to a smile when they see that it is a corvette.....I've been getting thumbs up all over the place now! :cool: :cheers:

 

elims emissions legal? **Texas, I know they're about to get a lot stricter here**

 

Can't say that I either lost or gained power but I'll tell you this:

In September I went to a local Corvette show, Bob McDormans Chevy. After I got out of the car, after backing into my spot, I found two guys laying on the blacktop under my car. One of them had a 95 in the next row and wanted to see why my car sounded so good. :lol:

15 minutes later NotSlo pulled in with his LT4 and muffler elims. He got out of his car and found another guy under the back of his.... :yesnod: :yesnod:

 

well all i have to say is this...

its ranges from vette to vette....try it out on your own...some love em some hate em...for me....did not like em.....took my torque away and made the car way too loud.....gave a droaning resonance on the highway.....

me.... targas worked nice on mine and gave me a kick in the pants SOTP feel like around 40-60.....ya really feel the torque curve kick in.....the L-98 likes its backpressure.....

its nice........
later jeff

 

I was told by a fellow forum member that was following me that my car sounded awesome, had a deep throaty growl

 

Yours does sound great Ken.. I'll do my sometime.

 

I was close to putting them on. Just out of curiosity, I stopped at a place that does state inspections, and the guy says as long as you have your cats still on, he thinks it's ok (he had a hard time speaking english :rolleyes: ) I didn't want to take his word for it, so I stopped at another place, and he said, "you don't have mufflers, you don't get a sticker". I asked whether the reasonator counted and he said no. So, I went home and searched the Texas laws and found this: § 547.604. Muffler Required
(a) A motor vehicle shall be equipped with a muffler in good working condition that continually operates to prevent excessive or unusual noise.
(b) A person may not use a muffler cutout, bypass, or similar device on a motor vehicle.
Acts 1995, 74th Leg., ch. 165, § 1, eff. Sept. 1, 1995.

Of course it's illegal to not have a front license plate either, and I don't have that on, so...I just don't know if I want to deal with possible hassles.

 

I had elims on my 94 for a couple months. They sounded cool but after a while I got sick of them, they were kind of obnoxious.
As far as performance is concerned, I don't think you will see neither a gain or loss, I know I didn't.
My 1/4 mi times & MPh were identical with elims on and after I switched to a B&B catback.

IMO, the only way you're going to see real performance gains from exhaust on a stock Lt1 car is with long tubes headers and eliminating the cats.
I think you are wise to just do elims or some other type of mufflers on if you're looking for a different sound. I would not even bother with an expensive cat back, the money can be spent in better places.
I wouldn't have the B&B on my car if I didn't get such a killer deal on it.

 

I had my front Y, cat & cat-back done together and picked up some nice 1/4mi gains (on my site). Vic'89, with a similar setup L98 had the same cat-back installed and that alone gave him some nice gains.

Now the L98 has effectively shorty headers unlike the LT1 cast manifold so we don't exactly have the same animal. But I can't see you loosing low end with muffler elims.

I'll have to ask Frank (Mr.MoJo) about that 1mph loss when the track opens this Spring. I don't know if it was a one day trial or over several weekends and the weather can make a huge difference at Raceway Park. Anyway I realy like the sound of his elims and his LT1 is still a little quicker than my L98.