How much difference

[Darknight]

I went to measure my exhaust today(correct me if i am wrong, but the length across is diameter right?), and found out its only 2 inches. I never thought it would be any less than 2.5 because the previous owner put all new pipes, mufflers, etc.

i wanted to get super 40 mufflers, these no name turbos arent doing the job.

how much difference will i feel and see, paying the money and getting 2.5 pipes on?

can i get performance from an adapter at the muffler and 2.5 mufflers? or do you only get the benefit from it going header all the way back.

my engine is in profile, .487 max lift, a little less than 10-1 compression, 1 5/8 hedmans

 

[night rider]

Yes across is dia..

Truthfully on that mild of a combo I wouldnt go to 2.5" pipes. Everybody has thier opinion on muffler types, and pipe sizes so everyone won't have the same answer.

Too to a pipe size thats too big for your combo and you will lose low rpm torque. Too small of a pipe and you will lose high rpm HP. If it's a car that sees street use alot then I myself rather take the top end power cut cause really how much time do you spend at 5500, 6000, 6500 rpm vs. 1500, 2000, 2500, 3000, 3500 rpm.

Depending on what "cheap turbo" mufflers you have, you may make more HP with those than the flowmasters. I have flowmasters on mine just cause they was laying around the yard, but they are one of the worst flowing performance muffler on the market. Alot of people do run them cause of the sound though.


I'm only running 2.25" pipes on my car and it has the power to run 11.50's at 118mph. 10.18:1 compression, shift at 6400 rpm, etc etc.

 

[Darknight]

I was thinking to at least go to a 2.25 inch, and maybe 2.5 in muffler, using an adapter at the rear of pipe. the car does have great pull up to 4800 then dies a little. the cam is still good up to 5800 along with my intake, carb and compression. it is a daily driver, but i will step on it, and might go do some illegal racing in the country.

I know the big debat over flowmasters, and everyone has preferences and flow numbers, and stats. I looked at dynoflow, borla, and the new eldebrock, and even the hooker aero chamber. In all honesty I think they all perform the same for a mild street car, maybe all the little differences are felt when your built to the capacity and every little HP matters and is needed for that extra
.10 or so. the super 40's sound great, keep some of the interior resonance down, and flow pretty good with enough back pressure to keep low end in line. and for prices on them, they cant be beat.

 

[Darknight]

Hey night- i am going to put 2.5 muffler diameter with a reducer/enlarger, going from my pipe to muffler. get the torque on pipe and maybe a little extra flow through the muffler, and if want to get bigger pipe later, its there on muffler already.

took the car out today, finally got valves down, still one clicking rocker, but runs perfect, 18 vacuum, carb tuned, pump shot dead on. now at 80mph it still wants to pull hard, so maybe the bigger muffler will help.

its between a super 40, and a magnaflow welded. most likely go with flowmaster, straight throughs, might as well do open pipe.

 

[night rider]

Darknight.. The 2.5" mufflers with adapter on pipes sounds good to me.

Yeah everybody has thier opinions on flowmasters.. I'm not to happy with them to say the least. Like I said many times.. They was the top dog 10 years ago, but they just lived on thier rep from back then and forgot about the R&D.. Where other companys has been doing R&D and coming up with much better performering mufflers. I am the type that trys to get every last litlle bit of power out of mine though.

Oh yeah.. I don't think your top end pull prob. is caused by your exhaust.. Yes too small of exhaust will hurt your top end, but it's not going fall off so strong like you said yours does..

I would think that to be caused by the heads just can't flow in the upper rpm range, fuel pump/supply cant keep up with the engine, valve springs too weak for your cam, or timing way off

 

[Darknight]

It could be my cam and heads. they are unported 291 humps. they flow 165 and unshrouded chambers, but i went with a mild cam 224/230 and .480 lift.
I figure street car, better go on the low side so you can have fun at lights.
I think I will see a little improvement on the exhaust, just getting a better mufffler than meineke is going to improve, the extra diameter cant hurt either.

next engine, i will either port these heads or get some aftermarket and see what all the hoopla is about. for a mild car this thing is pretty fast, or i am just old and everything is fast. once i get gears and locker, i will take it to the 1/4 out here in baytown.

 

[night rider]

Dark.. I wouldnt say cam.. I would look more towards heads..

I'm running a good bit smaller cam than you are (272/284*, 216/228* @.050", .454"/.480" lift, 112 lsa) and 1.6 rockers which bumps lift to .484"/.512" and .050" duration to around 218/230*

I pull great up through the mid 6K range.. I ran it out to test my drop off point and it flatens out at 6700 rpm.. Pulls just as hard at 5K as it does at 2500, still pulling great at my 6400 rpm shift point

 

[Darknight]

when you went to 1.6 rockers did you have to go up on pushrod length? i never was good at understanding that part. if i cam across a set i might put those on and see if it opens a little more. but like you said, the heads problably just arent keeping up with the rest

 

[night rider]

No, I didnt have to change push rod lenght. Push rod lenght changes when you install longer valves, mill heads, deck block, etc.

But now on most stock heads you will have to enlarge the push rod guide slot when you make a ratio change. The 1.6's will cause the push rod to run against slot.

There's a tool made for the DIYer to do it at home called a lotus (spelling) tool, sells for 40-50 bucks.

Or you can install screw in studs and guide plates then drill the push rod slots out with a 7/16" to 1/2" drill bit.

I went with the screw in studs cause I was pulling the stock pressed in studs out some on these heads on the last engine I had them on.

 

[Darknight]

i think i will just yank the 010 engine i have in my parts car, and make and experiment out of it. has 882 heads, yes i know they suck, but maybe i can get an idiot in houston to pay me for them. anyways, build the bottom with flat tops and get a edelbrock etec set or a vortec head and go with 1.5's and 1.6's. go with a 292 magnum cam or 274xe, and then when bored one weekend put it in and see.