Aftermarket headers

[charliex]

5 cars tested, 4 different manufacturer header, 5 cars with AFR ratio's in 13.5 to 13.8 AFR's at WOT, which is not good at all, they're ok at first then they drift, we're not currently supporting headers as an ok change for the SC kits or tunes unless its been specifically tuned for them.

Check 'em if you got 'em.

[Randy Chase]

We tested headers on my car years ago (naturally aspirated). Most lost power. Eventually I went with a ported stock header which seemed fine...then a stage 3 header from Lotus Sport.

Funny, this was the one thing I was told by Lotus guys when I first got my car... careful with the headers. They tuned for them. I was told this many times.

[charliex]

Yup agreed, saw a 20HP power loss on most.

Btw this is 5 cars tested recently (not just by us either), we've already seen (and had posted about the losses before) but more and more people are coming to me and saying our cars are running lean, and i usually find out too late they've got headers.

[SweetDaddyD]

Paging GTSRasta. GTSRasta to the red phone!

[turbophil]

For whatever it's worth, I also had a huge power loss when I bolted up headers... I did tune afterwords and got all my power back and then some...

The BIG CAVEAT is that I didn't have my tune pre-header optimised. It's quite possible that I may have been able to get the same power or more with stock headers... So what's the point? As Charlie said, without tuning, the headers (I have anyway) lose signifcant power, ceteris parabis...

Best,

Phil

[dmh]

This is not Lotus specific! Contrary to popular opinion and interner lore, headers are not now nor were they ever bolt-on horsepower generators. If they are any good they will help with scavenging which leans out the a/f mixture by allowing more charge into the cylinders. It used to be that you had to re-jet; now you have to re-tune for more fuel.

[turbophil]

Originally Posted by dmh

This is not Lotus specific! Contrary to popular opinion and interner lore, headers are not now nor were they ever bolt-on horsepower generators. If they are any good they will help with scavenging which leans out the a/f mixture by allowing more charge into the cylinders. It used to be that you had to re-jet; now you have to re-tune for more fuel.

True in most cases- However, with the headers I have the AFRs didn't change to the lean or rich much at all... I mainly just lost power... Crazy, I know... I didn't data log the initial run so I didn't have much to analyze. I just proceeded to tune and get the power up...and then kept going

Best,

Phil

Edit: For clarification: I"m running the weapn R headers. I have a gut feeling that they free'ed up some power after tuning, but definately lost power without tuning...

[Dave]

Originally Posted by dmh

It used to be that you had to re-jet; now you have to re-tune for more fuel.

Exactly! If you can't tune, you will likely not gain much, if any, and what you do gain will only be temporary and lean. With the EFI, I've been able to tune/recover almost 15HP that was lost with my airflow improvements. Here is a same day dnyo done within 5 minutes. This was with a 3.2" pulley, and we also mounted up the stock 3.4" a couple hours later with similar results - dangerously lean A/Fs with the Katana (see below). We had to add a fair amount of fuel to my EFI map to compensate for the additional flow. Car runs like an absolute bat out of heck with much lower A/Fs and more power/torque.

I'm running: FF CAI, PPE FI big bore headers, decat, 2bular 6", ported TB & S/C manifolds.

[shay2nak]

charlie i'm going to pick up the 2bular header soon, but I'm on stock header and my A/F is at 13.5 and then some. I've been driving like this for a good while now. I posted my dyno in your header thread on MM. Haven't been there yet today. Looks like my car will require your retune service.

[iana]

Originally Posted by charliex

5 cars tested, 4 different manufacturer header, 5 cars with AFR ratio's in 13.5 to 13.8 AFR's at WOT, which is not good at all, they're ok at first then they drift, we're not currently supporting headers as an ok change for the SC kits or tunes unless its been specifically tuned for them.

Check 'em if you got 'em.

Was Quicksilver 4-2-1 extractor (UK) one of the 4 tested?

[dustylax]

headers on a lot of different applications will lose power because you lose back pressure, so your 7psi pulley is now lets say 5psi (just an example). Along w/changes in AFR's, so like charlie said, get tuned correctly for your exact setup.

[charliex]

The problems we see like this on the lotus are rarely lotus specific, the reasons as to why it happens are usually the same across the board, there's really no difference between it and any other car.

don'ts
change pulley sizes
change fuel pressure
change injectors
change headers
change the position of the maf or the way the air flows in without checking it for poor airflow, or being too close to the throttle body.
larger throttle bodies, without testing the results or knowing what it is you're wanting to achieve with them.
spinning things off ebay

exhausts are usually ok unless they cause more of a restriction.


if you don't have access to a wideband, don't mod your car j/k, pull the plugs and check for signs of detonation thats usually straightforward enough.

ngk have a good article , there are lots off google, remember detonation can make plugs look cleaner, and that the best time to read them is directly after a spirited drive or dyno run, not after you wander about town or on the cool down lap.

NGK Spark Plugs USA

Spark plug reading


ngk's plug images from the 70's
Spark Plugs

feel free to post pictures of your plugs if you have trouble reading them.

cheers.

[BatmobileS240]

charlie - do you already have tunes available for aftermarket headers, for those that can't have you tune their cars in person?

[charliex]

no sorry i don't, i've been tuning peoples cars for their specific setups, but no generalised tune, there are so many combinations, i just wanted to make sure people are aware of it, since we've seen it so many times and had a few customers come back after buying the standard tunes and seeing running problems, power loss and way off AFR's.

i do have the forcefed race header for my car, that when i get around to installing i will make a tune for, and my car is pretty much stock other than the gotham.

[BatmobileS240]

I might just have to follow your mod path then the 06/07 gotham tunes on your site work for S240 cars right?

[andrewgotanelise]

Originally Posted by shay2nak

charlie i'm going to pick up the 2bular header soon, but I'm on stock header and my A/F is at 13.5 and then some. I've been driving like this for a good while now. I posted my dyno in your header thread on MM. Haven't been there yet today. Looks like my car will require your retune service.

Let me know if you can get charlie down to the L.A. area we can split the dyno costs

[charliex]

yeah they will, just less of a hp increase,

[GTsRasta]

Originally Posted by SweetDaddyD

Paging GTSRasta. GTSRasta to the red phone!

[SweetDaddyD]

Originally Posted by GTsRasta

You are the resident header promoter. Poster of dyno charts, etc.

[cory1000]

Originally Posted by SweetDaddyD

You are the resident header promoter. Poster of dyno charts, etc.