kllrvet

iTrader: (4)

April 2010, my car dropped a valve, and totally destroyed the motor.

April 2011, my new motor was completed and installed in my car.

http://forums.corvetteforum.com/c6-z...l-up-deth.html


The combo was as follows:

Stock milled heads .030
Bronze exhaust guides
Solid stainless Ferrea exhaust valves
Ragin Racin punisher cam and complimenting springs
Smith brothers 3/8 pushrods
Morel link bar lifters
Mahle 11.5:1 forged pistons (lighter that the stock cast ones BTW)
Arp head bolts
Arp 2000 rod bolts
Stock rods reconditioned by Crower
Aviad trap door oil pan insert
Lingenfelter zr1 twin disk clutch
Tick master cylinder
Ported throttle body by Jeremy Formato
Vararam intake
LG 1 3/4 headers
Modded stock mufflers
Yella Terra roller rockers

This combo netted me a respectful 539 rwhp/499 rwtq. I was happy with it, and yet a bit disappointed. I always thought I was 15-20 rwhp down with the 1 3/4 headers VS having 1 7/8 headers. I really wanted at least 550 rwhp, so I had a BAD case of header envy.

A couple of months ago, I started a thread about a power dip that I had at about 2500 rpm:
http://forums.corvetteforum.com/c6-z...isher-cam.html

Not long after the thread was posted, I got a call from Louis, at LG Motorsports. He called to help me understand why there was a dip in power, discussing overlap, intake runner length, and header primary tube length. During our conversation, I of course mentioned my header envy. Louis offered to send me a set of their 1 7/8 headers to try out.

I was so excited, when I got them! I couldn't wait to unlock the power I was missing out on!!! After spending a few days installing them in my garage, I took the car out...untuned BTW. It was a different animal...but not exactly what I expected. My car used to wheel spin so hard at WOT in 2nd gear, it tried to swap ends! With the 1 7/8 headers, ..... the was NO wheel spin in 2nd gear. The car was noticeably slower.....
I called Louis to tell him what I had experienced. It wasn't to complain, but to just to share what I had found. He told me that he wasn't surprised at all, as LG Motorsports had found that 1 7/8 headers really weren't needed until the motor exceeded 440CI.

Here is what the dyno showed after tuning:





To make sure we were comparing apples to apples weather wise, here are the conditions of those runs:



There was a considerable loss in low end power, and no gain in top end. Hmmmmm.... so much for my header envy.....

Tony

82cetuner

iTrader: (9)

I couldnt agree with this more, amost everyone out here running 1 7/8 headers on there stock cube cars are leaving power on the table especially in the mid range. 95 percent of the guys that are running 1 7/8 are running headers that are oversized for there build.

not saying 1 7/8 doesnt have its advantages but not at the primary right next to the exhaust port it simply slows the velocity down to much.

header envy gets alot of people it ALMOST got me, until I saw the gains that a set of stepped headers made over 1 7/8 headers so I went with a set of 1 3/4 headers stepped to 1 7/8 they showed almost 10 to 15 more hp threw the power band on a stock 2010 camaro. so I think they will be perfect for my 418 build, and just to prove thet 1 3/4 is not restrictive on big power engines they dynoed a car at over 700hp on the same headers

midwestjunk

iTrader: (2)

I assume this is all n/a. How about a nitrous motor? I have the old slp 1-3/4 long tubes and I always thought I'd gain some power switching to a good set of 1-7/8 or a 2" stepped to 1-7/8. I know I am only 346ci. But I found this thread very interesting. I made 600hp@ wheels on the bottle. What do u guys think? Would the test show any gains if the same car did a nitrous pull before and after the header swap?

4doortypels

iTrader: (39)

i love this thread... seems like everyone on here thinks fast 102 are the god of bolt ons along with the biggest primaries you can get... motors are glorified air pumps... combination is key to any good build, not your expensive part list people ramble off... sad to see 400 plus cubes make 450 whp when you see stock bottom ends making more with just a good set of ported stock heads and nice spec ed cam... i dont see how people can loose 15tq accross the board to say they made 5 more peak hp... just my thoughts

nice numbers

82cetuner

iTrader: (9)

from my personal thoughts most mods are going to have the same effect on N/A Nitrouse and Boosted engines. for instance if you see a gain with a set of heads on one type you will see the gain on all setups, if you see a loss you will see them on all type builds as well.

of coarse Cams and heads do need to be taken into consideration for each build most bolt ons dont.

for instance any custom made hot side pipes are going to net more hp than using stock truck manifolds for boosted engines.

alot of people think they have bigger cubes they need bigger everything but thats not always the case its a proper setup that really matters.

the thing is you rarly ever see back to back dyno tests on header swaps, I bet if someone did do them you would see alot of setups losing power going up form 1 3/4 to 1 7/8

BURN'EM

iTrader: (11)

My car lost alot of mid range with 1 7/8" N/A. But picked up 42 HP. 73TQ through out an entire pull once sprayed. If my car was a stick I would have to had stayed with a 1 3/4 for power, but
my converter hides alot of the headers loss.

corvet786c

iTrader: (6)

If I am not mistaken LG has on his site a comparisson of their 1 3/4 Super pros vs leading competition 1 7/8. Their super pros made more power.

SweetS10V8

iTrader: (4)

I feel exactly the same. Have to choose your battles, and thats one where people have gone completly to "Bigger is better". Im not doing this trying to help them.....

Dyno Junkie

As important as the primary pipe size is, the collectors size is also just as important!

That is the collector size of these two sets of extractors?

82cetuner

iTrader: (9)

these comparrisons are with 3 inch collectors pretty much the standered and duel 3 inch collectors are good for well over 600 HP to the wheeles

kllrvet

iTrader: (4)

The collectors on both are a merge style with a fire cone and a 3 inch outlet.

This is what the 1 7/8 look like:




This is what the 1 3/4 look like:



Tony

revtech101

Were the ports rough where it meets the heads? Most headers need a bit of cleaning before installing them. It is also likely the bigger headers would need to be port matched to your cylinder heads, meaning the exhaust ports need to be opened up.

98BLOWNZ28

iTrader: (10)

That's interesting. I like the proof you provided as well. I'm going with 1 7/8 stepped to 2", but I also have a blower......

Blk98Vert

iTrader: (2)

Is it just me or would the shorter primaries on the 1 7/8s account for the midrange loss? The 1 3/4 are longer for better power on the street. I just find it wierd that the f body design 1 7/8s show gains but these show the opposite

Dyno Junkie

I was thinking the same thing, also it looks like the longer 1 3/4" extractors reduce down a lot more in the collectors than the larger shorter 1 7/8" set.

Collector size is as important as primary pipe size.

litle88

iTrader: (20)

Two guys I know have 1 7/8's on SBE Ls1's and are making 500 or more hp with H/c/I one is thru an auto the other M6. Something is wrong there, it would be nice to know what. I seriously don't think that 1 7/8 are for 440+ cubes, with that I'd be in the 2" headers. I am 418 and went with 2" headers do we shall see.

firefighter813x

iTrader: (6)

I've called numerous sponsors from the corvette forum and ls1tech and received many different answers regarding 1 3/4 vs 1 7/8. MY C6 has 1 3/4 ARH with catted 2.5 exhaust to Corsa sports and makes 420lbs of torque through an A6 with stock LS2 intake, AFR 205's and a 224 cam.

kllrvet

iTrader: (4)

Im with you on this, I'd like to find a set of long 1 7/8 to test.

kllrvet

iTrader: (4)

You would never know what they do or don't without some testing comparison testing like I did.

Since 1 7/8 headers were the generally suggested header for my combo, I thought my numbers were a fluke. I did some searching, and comparing my numbers to others with similar combos. I found that my numbers were right in line with what others had. So, it seems to me that most don't miss what they never had.

Tony

DietCoke

iTrader: (18)

The factory port is less then 1 5/8 inches. There is nothing to match. The header is significantly larger then the exhaust port.