93formto98T/A

iTrader: (28)

So here's the problem I'm faced with; I'm putting a forged and F1R procharged LS7 into a conversion/swap car. The setup will be shooting for 1100rwhp through a T56 on pump and meth. If it was an fbody or vette I could easily get my hands on 2" LT headers but this is just not the case. Currently, the largest premade LT headers available for the swap are 1 7/8- these are ~$800. I'm not willing to leave my car at the shop for any period to have custom headers made. I read in another thread that it is not absolutely crucial to run larger headers on blower setups vs NA setups. I did locate a shop that would custom make 2" swap headers (without needing my car there) in mild steel and ceramic coated for $2000 but is it really worth the price difference? I would greatly appreciate educated input here as to whether or not the 1 7/8 vs 2 headers are going to make a huge power difference with my setup. Thanks in advance.

sciff5

iTrader: (1)

I think you'll still make 1100whp... It sounds like 1200$ of wasted money you could spend on a nitrous kit pushing a 300 shot.. That should make sure you reach your goals plus some!

93formto98T/A

iTrader: (28)

The goal of this setup is to be as "simple and reliable" as possible. I have no personal experience with nitrous and don't have any desire to try it with this setup. After all, with ~1300fwhp some would start to question the reliability/durability of the ls7 block at that point...

DeltaT

iTrader: (5)

Not worth it. I don't think you'd lose more than 30HP at your peak. I just had to make a similar choice. You'll get probably 90% of the functionality of the more expensive LT's at only 40% of the price. If someone ever sponsors you and you can buy anything, then do the upgrade on their dime.

Jim

stevieturbo

I had custom 2" headers made for mine over a year ago.

Whether related or not....Ive went slower ever since ( was using 1 3/4" Pacesetters before lol )

I had a lot of problems last year, so Im still hopeful this year. As an extreme measure if I dont get the results I want later in the year. I may consider re-fitting the old ones.

I highly doubt the lack of performance is due to the headers though.

93formto98T/A

iTrader: (28)

Thanks for the input guys. Your comments are reinforcing what I am leaning towards -1 7/8. In an ideal situation I would grab 2" just to know there are zero exhaust restrictions but at the rate all these little costs keep adding up to be able to get the engine into the car and running, the $1200 is starting to become a big obstacle to overcome.

stevieturbo

If I had a choice, I would have got 1 7/8". Couldnt find anyone in the UK who could do it though at the time.

Jake@EPP

2in or 1/78 to 2.0 would be optimal for that amount of exhaust energy. Pump and meth is going to be a long shot unless you have a sub zero intercooler lol. That F1R will be getting toasty uptop as you will be pushing it hard, HOT IAT's, just remember that the blower takes a good amount of power to spin as well. You might be better off with a f2m.

sciff5

iTrader: (1)

Nitrous is just about the most simple major power adder ever created. Even if you want to keep it simple and just add 50-100 shot to keep the IATs down you'll still be better overall, and I got my kit, which is good for a 300 shot for 500 used here on the forum.

Also I would trust the manufacturers mass producing the 1 7/8 headers more than your local performance shop making a 1 off peice. These major companies pour a lot of money into development before they release a new product and generally speaking that research usually leads to better performance.

Jake@EPP

Depending on the shop, you may come out with a better header. Try a good chassis shop to see what they offer. Kooks also does one off customs if thats on the adgenda.

While nitrous cools IAT's, its also a oxidizer.

93formto98T/A

iTrader: (28)

The aftermarket supplier of these 1 7/8 swap headers is Sanderson, not well known in the ls1 community as they don't have a huge selection for us yet. It's also the same company that I talked the head fabricator into freehanding a 2" set based off the 1 7/8 jig they have. So the quality fit and finish should be the same just $1200 more. These are my two options and I want to know if it's worth the extra $$ for the 2" LTs.

As for the F2, I've brought that up on numerous occasions to my builder but he is confident I will reach my power goals with the F1R. I'll be pretty upset if he's not right...

ALLBOTTLE

iTrader: (13)

call lemons headers in California chances are he already had as a 2" sbc setup they may require the bmr k-member though.

93formto98T/A

iTrader: (28)

This is an LS7 going into an import. No BMR K for this car...

kp

iTrader: (34)

I'm using 1 7/8 primary with a 3" collector into a smashed up 3" Y-pipe into a flowmaster merge and a single 4" muffler and everything is working fine. I wouldnt be scared to add a couple more hundred HP with the headers and exhaust that are on the car.

I would like to try 2" headers with 3.5" collectors and Y-pipe but I dont think it will pick up much. IMO an N/A or nitrous engine that relies more on exhaust scavenging for a clean cylinder fill will be more affected by header primary/collector size then a supercharged engine.

sciff5

iTrader: (1)

Nice! what import?

93formto98T/A

iTrader: (28)

Fd Rx7

sciff5

iTrader: (1)

WTF is this posted on v8rx7forum.com I totally need pics of this!!

I have an Ls1 FC. What procharger setup are you using and how does it fit. Some pics would be awsome. I am thinking of going FI later on and I am torn between a twin screw, turbo, or procharger.

Now knowing that you are talking about the JTR longtubes, I would say that you may see a sizeable increase going to custom 2" primaries. I used to have the bbk LT headers on my FC and they were a much more full length header than the JTRs that I got after that. I thought you were referring to the Kooks 1 7/8 long tubes which are a work of art.

93formto98T/A

iTrader: (28)

Not to get the post off topic but I am a member on v8rx7forum as well. No, the project is not yet posted as the car is still under the knife getting a one off sheetmetal widebody welded on as well as carbon doors, hood, trunk, and FG bumper for weight reduction then custom paint. I'm running the procharger w/fbody brackets and pulleys which will be no prob. I'll just have to scoot the rad around a bit and have already come up with a great intake idea. Now...back on topic.

whiteseven

iTrader: (8)

I think Jake pretty much answered your question for the correct sizing. Not trying to be negative, but with the amount of money your spending on this project (seems pretty high dollar LS7/Procharger/Carbon fiber body panels) having a custom set of header fabricated should have been calculated in to your initial budget.

You're going to need to sacrifice the notion that you don't want to leave the car in a fabricators shop because what you need doesn't exist on the FD or FC LS swapped Rx7 market. It's going to cost between 1500 and 2000 to have them made. I've been looking into a local fab shop to get a set of headers made for my car that are stainless steel since no one offers a set for the FC in stainless. I'm having the same shop also fab a full 3 inch exhaust to match up with them. Had them do my initial swap exhaust (stock manifolds full dual 2.5 inch) and the quality has been excellent.

93formto98T/A

iTrader: (28)

I'm still not convinced either way here... So far we have a few guys who have actually run the 1 7/8 and or 2" and have recommended the 1 7/8 and we have a few respected people who are recommending 2" but can't give me the real world difference between them. Anybody else? What I really want to know outta this is given the setup, will there be more than a 50hp difference between a 1 7/8 LT header and a 2" LT header made and routed the exact same way? If not then it is not cost effective for me at $1200 when $1200 may be all I need to finish things up and not have to wait another month or two to save up....